Symposium Organizers
Stephen Steiner, MIT
Stephanie Brock, Wayne State University
Alexander Eychmueller, TU Dresden
Nicholas Leventis, Missouri University of Science and Technology
Symposium Support
Aerogel Technologies, LLC
Aspen Aerogels, Inc.
BASF Polyurethanes GmbH
Blueshift
JEOL USA, Inc.
NASA–Glenn Research Center
NM3.2: Energy Production and Storage
Session Chairs
Nicholas Leventis
Stephen Steiner
Tuesday AM, April 18, 2017
PCC West, 100 Level, Room 105 BC
11:45 AM - *NM3.2.01
Aerogels—An Architectural Guide to Advances in Energy
Debra Rolison 1
1 , U.S. Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractAerogels and aerogel-like materials are composites of being and nothingness. They are architectures one constructs on the benchtop. They are hierarchically porous nanoscale materials that are innately multifunctional—they are the very definition of the new frontier of mesoscale science. A rainbow of you-name-it! applications intersects today’s approach to aerogel science [1]. Our team has found that aerogels serve as a powerful guide in reimagining materials and electrodes in electrochemical energy science. Key consumer and military portable power sources (e.g., batteries, fuel cells, supercapacitors) must balance multiple functions (molecular mass transport, ionic/electronic/thermal conductivity, and electron-transfer kinetics) even though these functions often require contradictory structures [2]. The design and fabrication of size- and energy-scalable three-dimensional multifunctional architectures from the appropriate nanoscale building blocks for charge storage seamlessly embodies all of the requisite functions. Even expressing a modest oxygen-evolution electrocatalyst in aerogel form allows us to take an underperforming oxide to state-of-the-art performance [3], further underscoring the importance of nothing and the unimportance of periodicity in energy-relevant nanoarchitectures [4].
[1] D.R. Rolison, J.W. Long, Acc. Chem. Res. 2007, 40, 854.
[2] D.R. Rolison, J.W. Long, J.C. Lytle, A.E. Fischer, C.P. Rhodes, T.M. McEvoy, M.E. Bourg, A.M. Lubers, Chem. Soc. Rev. 2009, 38, 226.
[3] C.N. Chervin, P.A. DeSario, J.F. Parker, E.S. Nelson, D.R. Rolison, and J.W. Long, ChemElectroChem 2016, 3, 1369.
[4] D.R. Rolison, Science 2003, 299, 1698.
12:15 PM - NM3.2.03
Aerogel Catalysts for Energy Applications
Elies Molins 1 , Monica Benito 1 , Ignasi Mata 1 , Jordi Llorca 2 , Adelina Vallribera 3
1 , ICMAB-CSIC, Barcelona Spain, 2 Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Barcelona Spain, 3 Facultat de Química, Universitat Autònoma de Barcelona, Bellaterra Spain
Show AbstractHydrogen is expected to play an important role in the post-fossil fuel economy, where it will be extensively used as energy carrier. For this reason, there is a great interest in the development of photocatalytic materials able to use the sunlight for hydrogen generation. Moreover, these materials should allow the synthesis of molecular hydrogen from renewable resources, such as water or alcohols, as for example bio-ethanol or the glycerol obtained as by-product in biodiesel production, ensuring that the technology is environmentally safe.
The photocatalysts for hydrogen generation are semiconducting materials that become excited by the incoming photons, generating electron-hole pairs. Provided that the lifetime of the excitation is long enough, electrons and holes can react with species adsorbed at the surface of the photocatalysts, which should present a very large surface area. The efficiency of the photocatalysts is highly enhanced by incorporating metal nanoparticles that capture electrons from the conduction band and transfer them to the hydrogen ions. A well-known photocatalyst used for this purpose is titania doped with gold nanoparticles, which can be prepared in nanoporous form by sol-gel chemistry and supercritical drying or lyophilization.
The problems with the transport and storage of hydrogen can be overcome by generating the hydrogen in place for its use either in power cells or for direct combustion. The applicability of this technology will be better if the photocatalytic reactors can be miniaturized, allowing hydrogen generation in the small scale. An example coming from our research is a silicone microreactor, which is formed by channels filled with gold-doped nanoporous titania. By tuning the composition and nanostructure of the photocatalyst, and by an accurate design of the channel structure, which can be built by 3D printing, we expect to obtain high efficiencies in simple microreactors that can be used in a wide diversity of applications.
Previous results of hydrogen generation by cobalt hydrotalcites in silica aerogels for the steam reforming of ethanol will be also shown. Our group has been also active in activating organic synthesis reactions by using aerogels, such as the Suzuki, Biginelli and Michaels reactions. Recently, we have demonstrated the activation of the Mizoroki-Heck reaction by the application of an electric field using Pd nanoparticles in a carbon aerogel acting as electrode.
Acknowledgements: This work is been funded through MINECO/FEDER grant ENE2015-63969-R.
12:30 PM - *
PANEL DISCUSSION: Gel Talks: Ideas the Aerogel Community Needs to Know
Show AbstractNM3.3: Polymer Aerogels
Session Chairs
Stephanie Brock
Kazuyoshi Kanamori
Tuesday PM, April 18, 2017
PCC West, 100 Level, Room 105 BC
2:30 PM - *NM3.3.01
Effect of Backbone Chemistry on Mechanical and Optical Properties of Polyimide Aerogels
Stephanie Vivod 1 , Mary Ann Meador 1 , Coleen Pugh 2
1 , NASA Glenn Research Center, Cleveland, Ohio, United States, 2 Polymer Science Department, The University of Akron, Akron, Ohio, United States
Show AbstractPolyimides are desirable materials for aeronautic and space applications due to their ability to retain their physical and mechanical properties over a wide range of temperatures.[i] Cross-linked polyimide aerogels[ii] are a form of polyimide with many attributes such as high porosity, low density, extremely high surface areas, low dielectric constants and low thermal conductivity. These characteristics make aerogels ideal for use as lightweight multi-functional structures for a variety of applications. The characteristic properties of the 3-dimensional structures formed through gelation of dianhydrides and diamines in polar aprotic solvents such as n-methyl-2-pyrrolidone (NMP) show a wide range of dependency on polymer concentration, monomeric structure and concentration, as well as crosslink density. In this study formulations were synthesized varying the length of the repeat unit (n), dianhydride fraction (Pyromellitic dianhydride (PMDA) and 4, 4’-Hexafluoroisopropylidene dipthalic anhydride (6FDA)), and the type of cross linker (1, 3, 5-triaminophenoxybenzene (TAB) or 1, 3, 5-benzenetricarbonyl trichloride (BTC)). Previous studies demonstrated that using PMDA in the backbone produced highly transparent aerogels while 6FDA gave aerogels that were more flexible but were completely opaque.[iii] This study examines use of a combination of 6FDA and PMDA to see if aerogels with both better transparency and flexibility can be fabricated. Structure property relationships of the resulting aerogels will be discussed
[i] Connell JW; Smith JG; Hergenrother PM; High Performance Polymers 2003, 15, 375-394
[ii] Meador, M. A. B.; Malow, E. J.; Silva, R.; Wright, S.; Quade, D.; Vivod, S. L.; Guo, H. Q.; Guo, J.; Cakmak, M.Mechanically Strong, Flexible Polyimide Aerogels Cross-Linked with Aromatic Triamine ACS Appl. Mater. Interfaces 2012, 4, 536– 544
[iii] Shinko, A. Structure and morphology control in polymer aerogels with low crosslink density. PhD. Dissertation, The University of Akron, 2015
3:00 PM - NM3.3.02
Shape Memory Polyurethane Aerogels for Deployable Panels and Biomimetic Applications
Nicholas Leventis 1 , Suraj Donthula 1 , Chandana Mandal 1 , James Schisler 1 , Theodora Leventis 1 , Chariklia Sotiriou-Leventis 1
1 , Missouri University of Science & Technology, Rolla, Missouri, United States
Show AbstractShape memory materials remember and return to an original shape when triggered by a suitable stimulus, typically a change in temperature. Shape memory polymers are pursued as cost-effective, lightweight, higher-strain tolerant alternatives to shape memory alloys. Shape memory polymeric aerogels (SMPA) comprise perhaps the ultimate refinement in terms of weight reduction in shape memory polymers. SMPAs have been synthesized based on aliphatic polyurethanes using a triisocyanate derivative of hexamethylene diisocyanate and a series of four short oligomeric derivatives of ethylene glycol (EG): H(OCH2CH2)nOH (1≤n≤4). Gelation of optimal materials was carried out at room temperature in CH3CN/acetone mixtures. Bulk densities varied in the 0.2-0.4 g cm-3 range, and typical porosities in the 70-80 v/v range. Despite that all skeletal frameworks consisted of micron-size particles, thermal conductivities remained relatively low (in the 50 mW m-1 K-1 range, giving R values for 1”-thick panels at 3 – that is, slightly better than fiberglass). Glass transition temperatures (Tg, tan δ maxima) varied from about 30 oC (n=4) to 70 oC (n=1). At and above Tg SMPAs showed rubber-like elasticity, while the elastic modulus decreased by about 1000 fold below the glass transition zone. That property gives rise to a shape memory effect that was demonstrated with deployable panels and biomimetic devices. The quality of that effect was evaluated with three individual figures of merit, (strain fixity, strain recovery and strain recovery rate), and a cumulative one, the fill factor. All samples showed some minor settling in the first temperature cycle that was traced to maximization of H-bonding interactions such as NH....O=C and NH….O(CH2)2. Nevertheless, the strain fixity was always >98%. After the first cycle, strain recovery increased to about 100% with a fill factor of about 0.7, which is considered high.
3:15 PM - NM3.3.03
Polyimide Aerogels with Aliphatic Links in the Oligomer Backbone—Towards More Flexible Aerogels
Haiquan Guo 1 , Mary Ann Meador 2 , Jessica Cashman 2
1 , Ohio Aerospace Institute, Cleveland, Ohio, United States, 2 , NASA Glenn Research Center, Cleveland, Ohio, United States
Show AbstractPolyimide aerogels with aliphatic links in the oligomer backbone: Towards more flexible aerogels
Haiquan Guo, Mary Ann Meador, and Jessica Cashman
Polyimide aerogels are important for many aerospace and commercial applications because of their high porosity, low density, low thermal conductivity, and higher modulus. Properties of polyimide aerogels can be tailored depending on the oligomer backbone structures. In this study, aliphatic diamines with six to twelve methylene groups were used to replace up to 90 % of the typical aromatic diamine in 1,3,5-triaminophenoxybenzene (TAB) cross-linked polyimide aerogels. The effect of the polyimide backbone structure on the properties of the aerogel, including density, shrinkage, porosity, contact angle thermal stability, and mechanical properties will be discussed.
3:30 PM - NM3.3.04
Flexible Polyisocyanate Based Aerogels
Roxana Trifu 1 , George Gould 1 , Shannon White 1
1 , Aspen Aerogels, Northborough, Massachusetts, United States
Show AbstractPolymeric aerogels with low thermal conductivities and good mechanical properties were developed at Aspen Aerogels by sol-gel chemistry and supercritical CO2 solvent extraction. The polyisocyanate-based aerogels reinforced with fabrics showed little to no brittle fracture with repeated flexing. The catalyst, crosslinker and isocyanate content and functionality played an important role on properties such as thermal conductivity, durability and flexural modulus at ambient and cryogenic temperatures. The polymeric aerogels maintained their low thermal conductivities, as low as 18 mW/mK at ambient pressure after mechanical impact and laundering. Applications of these aerogels in aerospace and diving are presented.
3:45 PM - NM3.3.05
Transparent Polymer Aerogels
Gabriel Iftime 1 , Barkev Keoshkerian 2 , Ravi Neelakantan 1 , Jianer Bao 1 , Quentin Van Overmeere 1
1 , Palo Alto Research Center, Palo Alto, California, United States, 2 , Xerox Research Centre of Canada, Mississauga, Ontario, Canada
Show AbstractPARC is developing transparent polymer aerogels for durable, low-cost, transparent insulation. The aerogel can be used to retrofit windowpanes, and other applications. Compared to silica aerogels, PARC’s transparent polymer aerogels have improved tensile strength, deformability, and optical properties. The overall objective of this work is fabrication of polymer aerogels with thermal conductivity < 0.020 W/m/K in air, haze lower than 1 %, and visible transmittance > 80 %, for a 3 mm-thick aerogel. The approach to high transparency and low scattering of light is based on pore sizes < 10 nm with a narrow pore size distribution, properties which are difficult to achieve with conventional aerogel synthetic methods. We will describe the current status of the work and the critical synthesis parameters that lead to small pore sizes, which include monomer-solvent compatibility, the molecular weight of the polymer linkage and other experimental conditions. We will also discuss how controlled “living” polymerization leads to a better control of the pore size distribution.
This work was partially funded through US Department of Energy ARPA-E’s SHIELD program.
NM3.4: Silica Aerogels and Composites
Session Chairs
Alexander Eychmueller
Stephanie Vivod
Tuesday PM, April 18, 2017
PCC West, 100 Level, Room 105 BC
4:30 PM - *NM3.4.01
Silicone-Based Organic-Inorganic Hybrid Aerogels and Xerogels
Kazuyoshi Kanamori 1
1 , Kyoto University, Kyoto Japan
Show AbstractSilica aerogels are known as a unique class of highly porous materials prepared via liquid-phase processes and supercritical drying. Carefully prepared silica aerogels possess pore structures in the length scale of a few tens nanometers, which provides visible-light transparency and very low thermal conductivity. However, mechanical strength is considerably low due to the fine porous structure and high porosity. In order to extend applications of aerogels, mechanical properties such as strength and flexibility must be improved for easier handling and forming, as well as for more efficient productivity by avoiding supercritical drying at high pressure. Through our recent research on the improvement of mechanical properties by organic-inorganic hybridization strategies, the following important findings have been obtained.
1. Polymethylsilsesquioxane (PMSQ)
Transparent aerogels based on the PMSQ (CH3SiO3/2) network from methyltrimethoxysilane have been prepared for the first time. A two-step acid-base process under the co-presence of a surfactant yields transparent PMSQ gels, which can be transformed into transparent aerogels by supercritical drying. The resultant PMSQ aerogels show high strength and resilience against compression-decompression, which allows ambient pressure drying to obtain aerogel-like xerogels simply by evaporation of the solvent.
2. Polyethylsilsesquioxane (PESQ) and polyvinylsilsesquioxane (PVSQ)
A two-step acid-base process for ethyl- and vinyltrimethoxysilane in a liquid surfactant solvent leads to transparent aerogels based on the PESQ (CH3CH2SiO3/2) and PVSQ (CH2=CHSiO3/2) network, respectively. Although these aerogels with larger substituent groups did not show significant improvements in the mechanical properties, a post cure process (vulcanization) of the PVSQ network with a radical initiator allows reaction of the vinyl groups to develop additional organic crosslinks in the network, significantly increasing the strength and resilience against compression-decompression. In a similar way to the case of PMSQ, ambient pressure drying of the wet PVSQ gels successfully yields aerogel-like xerogels.
3. Hexylene-bridged polysilsesquioxane (HBPSQ) and ethylene-bridged polymethylsiloxane (EBPMS)
Pre-installed organic bridges in the alkoxysilane precursors may play a similar role to the vulcanized PVSQ network in terms of the mechanical properties. Transparent aerogels have been obtained from 1,6-bis(trimethoxysilyl)hexane and 1,2-bis(methyldiethoxysilyl)ethane, which give HBPSQ (O3/2Si−(CH2)6−SiO3/2) and EBPMS (O2/2CH3Si−(CH2)2−SiCH3O2/2) networks, respectively. The both precursors provide the networks with reduced crosslinking density, which imparts viscoelastic properties to the resultant aerogels. Aerogels based on the trimethylsilylated HBPSQ and pristine EBPMS networks show higher bending strength and strain, and aerogel-like xerogels have also been obtained via ambient pressure drying.
5:00 PM - NM3.4.02
Advanced Composite Porous Materials—Silica Aerogel with Nanotube Fillers
Galit Bar 1 , Raz Gvishi 1 , Anastasiya Sedova 2 , Bojana Visic 2 , Reshef Tenne 2
1 , Soreq NRC, Yavne Israel, 2 , Weizmann Institute of Science, Rehovot Israel
Show AbstractPorous silica with meso-size pores and large surface area is made by solgel technology and followed by either ambient drying or supercritical drying. The porous silica can be used as a solid matrix for encapsulation of functional nano-sized dopants. Optional applications may involve chemical catalysis, photo initiated processes, optical sensing, chemical filtering and slow release of medication or cosmetics.
Interesting classes of functional materials are nanospheres and nanotubes. These particles can be made of organic or inorganic compositions. Nanotubes are normally a few tenths nanometers in diameter and a few micrometers long. Both organic and inorganic nanotubes present unique mechanical, electrical and optical properties. The addition of nanotubes to porous silica may affect the properties of the silica matrix and also the nanotubes.
We studied the mechanical and optical properties of silica aerogel with two types of nanotubes: organic carbon-nanotubes (CNT) and WS2 inorganic nanotubes (INT-WS2). Nanotubes dispersion in silica matrix is different for CNT and INT-WS2. CNT are more flexible and due to strong electrostatic attraction form aggregates, while INT-WS2 have inert surface and thus maintain their linear form and disperse well in solution. In addition, we found by gas sorption analysis that CNT induce changes on the porous structure of the silica matrix, while INT-WS2 behave like needles in the silica and do not interfere with the pores morphology.
The mechanical properties were studied by compression tests and three-point bending. Both types of nanotubes improved the mechanical strength of the silica matrix. Optical measurements of absorption show nonlinear refraction behavior for the pure silica aerogel, while the composite aerogel with INT-WS2 present two exciton peaks. The exciton peaks are attributed to the semiconducting behavior of WS2. The extinction spectra of the composite material revealed changes in the plasmons of the INT-WS2 due to interaction with the silica.
5:15 PM - NM3.4.03
Rapid Fabrication of Native, Cross-Linked and Hybrid Aerogels
Massimo Bertino 1 , Lauren White 1 , Tyler Selden 1 , Charles Cartin 1 , Joseph Angello 1 , Jan Kosny 2 , Nitin Shukla 2 , Lorenz Ratke 3 , Barbara Milow 3 , Marina Schwan 3
1 , Virginia Commonwealth University, Richmond, Virginia, United States, 2 , Fraunhofer Center for Sustainable Energy Systems, Boston, Massachusetts, United States, 3 , DLR, Cologne Germany
Show Abstract
This presentation will discuss fabrication techniques that reduce the manufacturing cost and time of aerogels. These techniques also provide the ability to adjust the thermal conductivity and mechanical properties with extreme accuracy and ease.
Modifications of the gelation chemistry coupled with ethanol supercritical drying eliminate the need for solvent exchange during the fabrication of both native and cross-linked aerogels. Elimination of solvent exchange shortens fabrication times from days to hours, independent of the sample dimensions.
Photopolymerization allows fabrication of hybrid aerogels consisting of native and cross-linked regions. This class of hybrid aerogels is particularly promising for thermal insulation that must withstand mechanical stress. For example, honeycombs consisting of a native cell core and cross-linked walls can be fabricated. Mechanical strength and thermal conductivity of these honeycombs can be modified by varying cell size and processing parameters. Additionally, surface cross-linking of an otherwise native aerogel creates an anchor region which can be secured to another material without shearing. Further studies focus upon fabricating large aerogel monoliths by freeze drying and will be discussed.
5:30 PM - NM3.4.04
Ambient-Dried Superinsulating and Monolithic Silica-Based Aerogels via the Use of Short Cellulose Fibers
Arnaud Rigacci 1 , Gediminas Markevicius 1 , Julien Jaxel 1 , Tatiana Budtova 1
1 , MINES ParisTech, Sophia Antipolis France
Show AbstractSilica-based aerogels have been studied for many decades for thermal superinsulation applications. Commercial products exhibiting excellent thermal insulation properties are already available on the market but ambient-drying routes are still intensively studied in order to compete with supercritical drying and further reduce associated costs of production. One of the main issues concerns preservation of monolithicity of the wet gels via ambient-drying. Most known works were related to use of non-woven fibrous mats to produce so-called blankets. Additionally, recent studies have demonstrated that it is possible to obtain superinsulating silica-based monoliths by using Ormosils precursors at lab-scale [1].
Within the present study, we have demonstrated that it is also possible to maintain macroscopic cohesion of the silica phase by using short cellulosic fibers and still working with TEOS. These ambient-dried monolithic organic-inorganic composites present morphological, structural and thermal properties similar to those of their supercritical CO2 counterparts. The presence of fibers lead to a significant improvement of mechanical properties as shown by 3-points bending characterization. Compared to pure silica samples, brittle behavior disappears but more interesting, ambient-dried composites appear more ductile than the supercritically dried ones.
Proof of concept was first demonstrated with reference cellulosic fibers (Tencel® product coming from Lyocel process). Then this lab-scale method was extended successfully to other cellulose based fibers such as wood and flax. Using different fiber geometries and concentrations as well as alternative fibers allowed us to achieve levels of thermal conductivity lower than 0.015 W/m.K in room conditions.
We will present global processing route, materials properties, comparison with supercritical drying and effect of fiber concentration and length on the properties of the composites.
Acknowledgements. The work was performed in the frame of projects “SILICA-CELL”, "SiCX“ and "AEROFIBRES“ supported by ADEME (French Environment and Energy Management Agency). We are grateful to Lenzing AG, Austria, for providing Tencel® fibers and to Stora Enso, Finland, for pulp fibers as well as ENERSENS for providing silica precursors.
[1] Hayase G, Kanamori K, Maeno A, Kaji H, Nakanishi K (2016) Dynamic spring-back behavior in evaporative drying of polymethylsilsesquioxane monolithic gels for low-density transparent thermal superinsulators, J Non-Cryst Solids 434:115-119
5:45 PM - NM3.4.05
Exploring the Versatile Surface Chemistry of Silica Aerogels for Multipurpose Application
Luisa Duraes 1 , Hajar Maleki 1 , Joao Vareda 1 , Alyne Lamy-Mendes 1 , Antonio Portugal 1
1 CIEPQPF, Department of Chemical Engineering, University of Coimbra, Coimbra Portugal
Show AbstractSilica aerogels are unique nanostructured materials that present extremely high porosity, usually above 90%. This feature makes them particularly attractive for thermal insulation, although their mechanical fragility still requires strategies of reinforcement which may compromise to some extent their most appealing properties. However, the use of silica aerogels can be matured for a broad range of other high-performance applications, and even improved for insulation application, by intensely exploring the tailoring of their surface chemistry. In fact, the enormous variety of silane precursors opens the way for highly versatile chemical routes. In this work, we present two examples of using reactive moieties in the silane precursors for the preparation silica aerogels for multipurpose application. In the first case, an acrylate containing silane (3-(trimethoxysilyl)propyl methacrylate) is used along with tetramethyl orthosilicate to produce an organically-modified silica network, which could be reinforced by adding tris[2-(acryloyloxy)ethyl] isocyanurate cross-linker and 1,6 - Bis(trimethoxysilyl) hexane as a spacer. The hybrid aerogels prepared by this route, either with supercritical drying (CO2) or ambient pressure drying, show an interesting combination of thermal insulation and mechanical properties and proved to be suitable for simulated Space environment condition [1]. Moreover, these aerogels could be chemically doped with silica-functionalized magnetite nanoparticles imparting magnetic behavior to the aerogels but also improving their thermal insulation performance [2]. Thus, these aerogels can be potentially used for several applications including magnetic separation and drug delivery. As a second example, amine and thiol-functionalized aerogels were used as adsorbents to capture heavy metals from wastewater and soils [3,4] by complexation, and the preparation of these materials could be accomplished using a combination of silanes with hydrophobic and the referred functional groups, in a compromise to ensure material stability and good adsorption capacities. Removal percentages of several metals above 90% were found for metal concentrations of environmental relevance [3]. The amine functionality could also be used in similar aerogels to bind nitrogen-modified carbon nanotubes (N-CNT) which can act as an opacifier phase of the silica aerogels [5].
[1] J Phys Chem C 119(2015)7689. [2] Micropor Mesopor Mater 232(2016)227. [3] J Sol-Gel Sci Technol (2017) DOI:10.1007/s10971-017-4326-y. [4] Adv Colloid Interf Sci 237(2016)28. [5] Proc of 3rd Int Sem. Aerogels, ISASF,2016,164.
Funding: Fundação Luso-Americana for the travel support (Proj. 73/20017). EU FP7-MC-ITN, GA No.264710; Calouste Gulbenkian Foundation, Project AeroMCatch (Proc.No.141735); CNPq for Ciência sem Fronteiras PhD fellowship 234184/2014-0/GDE of A. L.-M.; FEDER funds through COMPETE and Portuguese Funds through FCT - projects POCI-01-0145-FEDER-006910 & UID/EQU/00102/2013.
NM3.5: Poster Session I: Aerogels and Aerogel Inspired Materials—Assemblies of 2D Nanostructures, Energy Storage, Silica, Nanocomposites and Polymer Aerogels
Session Chairs
Alexander Eychmueller
Stephen Steiner
Wednesday AM, April 19, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - NM3.5.01
Designing Benzoxazine-Based Carbon Aerogel as Electrode Materials for Supercapacitors
Thanyalak Chaisuwan 1 , Sujitra Wongkasemjit 1
1 , Chulalongkorn University, Bangkok Thailand
Show AbstractThe electrodes are the main part of the supercapacitors, so the electrode materials are the most important factor to determine the properties of supercapacitors. Carbon materials are widely used for supercapacitor electrodes because of their relatively low cost, high surface area, good electrical conductivity and excellent chemical stability. In this study, polybenzoxazine, as a novel class of thermosetting phenolic resin, was chosen as an alternative precursor to prepare carbon aerogel used as an electrode for supercapacitors. The effects of soft template and CO2 activation on their pore structures were studied. It was found that polybenzoxazine with added soft template and CO2 activation exhibited remarkable improvement in textural properties with the surface area of 494 m2/g and the total pore volume of 0.81 cm2/g. The electrochemical measurement in 6 M KOH electrolyte showed that CO2 activation leads to better capacitive performances with the specific capacitance of 386.01 F/g at rate 1 mV/s. The results indicated that polybenzoxazine can produce carbon aerogel electrode materials with low cost and high performance for supercapacitors.
9:00 PM - NM3.5.02
3D Porous Graphene Nanostructure Fabricated with a Simple, Fast, Scalable Process for Applications in High Performance Flexible Gel-Type Supercapacitors
Shih-Yuan Lu 1 , Chun-Chieh Wang 1 , Ji-Yuan Liang 1
1 , National Tsing Hua University, Hsin-chu Taiwan
Show AbstractA simple, fast, and scalable mix-and-heat process was developed for production of three-dimensional (3D) porous graphene nanostructure. The process involves only mixing and heating of starch and a graphene oxide (GO) suspension at 90 oC for 10 min to form 3D graphene monoliths, from which a three-dimensionally well-connected porous graphene nanostructure, starch/RGO, possessing a high specific surface area of 1519 m2/g was obtained through common carbonization and activation treatments. No time-consuming hydrothermal or sol-gel chemistries and no energy-demanding supercritical fluid or freeze drying operations are needed to form the 3D graphene monoliths. The starch/RGO material was applied as the electrode material to fabricate flexible, gel-type symmetric supercapacitors of outstanding capacitive performances, delivering a high energy density of 19.8 Wh/kg at the power density of 0.5 kW/kg and exhibiting an excellent high rate capability of a high power density of 9.9 kW/kg at the energy density of 9.6 Wh/kg, among the highest for carbon material based, gel-type, symmetric supercapacitors. These excellent capacitive performances may be attributed to the advantageous structural features of the starch/RGO material, including the large surfaces exposed to the electrolyte ions for capacitance generation, highly porous structure for fast mass transfer of the electrolyte ions, and three-dimensionally well-connected conductive paths for the involved charge transport. The starch/RGO based supercapacitor exhibited outstanding mechanical stability with a retention rate of 90% in both energy and power densities at a large bending angle of 138o. It was also found that the starch/RGO based supercapacitor exhibited optimal performances in both energy and power densities at 80 oC and is thus applicable in a wide temperature range environment.
9:00 PM - NM3.5.03
Development of Low Density Silica Aerogels for Laser Induced Plasma Studies
A. Venkateswara Rao 1 2 , Channprit Kaur 2 , A. A. Pisal 1 , S. Chaurasia 2 , M.N. Deo 2 , S. M. Sharma 2
1 , Shivaji University, Kolhapur India, 2 High Pressure and Synchrotron Radiation Physics, Bhabha Atomic Research Center, Mumbai India
Show AbstractThe interaction of laser radiation with low density aerogels is of crucial importance in areas such as the creation of coherent radiation sources in the X-ray range, simulation of astrophysical as well as nuclear fusion phenomena in laboratory and fundamental studies of the properties of soft condensed matter under dynamic pressure in the Mbar range. In the present paper, the experimental results on the
X-ray emission of laser induced plasma in undoped, Cr- doped and organically modified silica aerogel targets, are reported. The aerogels were produced by the sol-gel processing of tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) followed by supercritical drying. Silica alcogels were produced using 0.001 M oxalic acid (C2 H4O4), 0.5 M ammonium hydroxides (NH4OH) catalysts. Different densities of aerogels varying from 0.02 to 0.06 g/cm3 have been obtained using different molar ratios of TEOS, MTMS, ethanol and catalysts. The laser, with intensity up to 2 x 104 W/m2 , interaction with TEOS and MTMS based and Cr- doped aerogels have been conducted using 30J/500 ps Nd : glass laser system. The resulting soft (0.8 – 1.56 Kev) and hard (>4 Kev) X-ray emissions have been measured using semiconductor photodiodes. It has been observed that the soft X-ray yield increases by a factor of two for the silica aerogel targets compared to the X-ray emission from the solid quartz target, whereas the hard X-ray yield reduces. The enhanced soft X-ray yield in silica aerogel targets is attributed to the large volume heating. The soft X-ray yield enhancement is also verified with the theoretical calculations.
9:00 PM - NM3.5.04
CuFe2O4 – SiO2 Aerogel and Xerogel Nanocomposites—Synthesis and Characterization
Danilo Loche 2 , Francesco Caddeo 1 , Maria Casula 2 , Anna Corrias 1
2 , University of Cagliari, Cagliari Italy, 1 , University of Kent, Canterbury United Kingdom
Show AbstractThe synthesis of CuFe2O4-SiO2 nanocomposites in form of aerogel and xerogel has been successfully achieved with high homogeneity. A sol-gel procedure involving the use of urea as a co-gelation agent has been used, ensuring a good control of the composition of the nanocomposites. The structural and morphological characterization of the samples has been carried out with a multi-technique approach involving the use of X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM), Thermo-gravimetric Analysis with simultaneous Differential Scanning Calorimetry (TGA\DSC), N2-Physisorption at 77K and X-Ray absorption spectroscopy (XAS). The analysis of both the X-Ray absorption near edge structure (XANES) and the extended X-Ray absorption fine structure (EXAFS) indicates that the Cu2+ ions occupy octahedral sites within the crystal structure of the copper ferrite and have a Jahn-Teller distorted coordination geometry, forming a tetragonal lattice. However, the Jahn-Teller distortion does not interest the Fe3+ ions, which form a cubic sub-lattice within the structure.
9:00 PM - NM3.5.05
Applications of Composites Scaffolds Synthesized by a Novel Sol-Gel/Freeze-Casting Hybrid Method under Ambient Conditions
Haw-Kai Chang 1
1 Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu Taiwan
Show AbstractBio-inspired porous composite scaffold has been extensively studied by using freeze-casting technique and varying polymer infiltration methods. In this study, a novel sol-gel/freeze-casting hybrid method is created and designed, which does not require sintering at high temperature or drying under low pressure. In terms of organics, these advantages are significantly valuable to prepare scaffold under mild conditions. Tetraethyl orthosilicate (TEOS) is utilized as the inorganic constituent of scaffolds followed by infiltrating various polymers to form composites. The complex shapes and architectures of scaffolds can be formed and molded easily by mixing organic polymers and inorganic ceramics as initial slurry. Composite scaffolds with varying 3D-dendridritic structures and porosities can be fabricated by controlling cooling rate, water content and the amount of infiltrated polymer and other parameters. Moreover, initial slurry with additive polymer can assist in maintaining the shape and provide a stable mechanical property, which will helpful reduce the number of cracks and further increase the porosity reaching over 95%. The compressive strength and toughness of composite scaffold are significantly enhanced compared to those of the inorganic scaffold. This novel hybrid method can synthesize scaffolds and composites under mild conditions, leading to diverse material selections and extensive potential applications. This research is funded by the Ministry of Science and Technology, Taiwan (MOST 103-2221-E-007-034-MY3).
9:00 PM - NM3.5.06
High Energy Density Ultrafast Supercapacitors Based on Edge Oriented Graphene in Graphitized Bacterial Cellulose Aerogel
Nazifah Islam 1 , Guofeng Ren 1 , Zhaoyang Fan 1
1 Electrical & Computer Engineering, Texas Tech University, Lubbock, Texas, United States
Show AbstractUltrafast electrical double layer supercapacitor that can be charged-discharged at frequencies more than 120 hertz could substitute the bulky electrolyte capacitor for many critical applications. To develop such ultrafast supercapacitors, electrodes should have macroporous structure with a large surface area and a high conductivity. Graphitized bacterial cellulose aerogel offers unique merits that include suitable porous structure for fast electrolyte transportation, highly conductive nanofiber network, large specific surface area, and very low mass density, providing an ideal platform to fabricate electrodes for ultrafast supercapacitors.
In this study, thin films of perpendicularly edge oriented graphene was grown inside the aerogel to further increase the accessible surface area. The graphitization of the cellulose and the graphene deposition was simultaneously implemented in a 10-minutes plasma chemical vapor deposition process. Using the as-synthesized freestanding aerogel as electrodes, ultrafast supercapacitors were fabricated with a record-breaking capacitance and energy density. High gravimetric and volumetric capacitance densities at alternating current (ac) line-frequency filtering have been achieved in both aqueous (6M KOH) and organic electrolytes (TEABF4 in acetonitrile). The energy density has been maximized by widening the operating voltage window up to 3V by use of organic electrolyte. We will present the detail studies, including the material and structural properties of the aerogel and the electrochemical studies of the ultrafast supercapacitors.
9:00 PM - NM3.5.08
Synthesis of Graphene-Silica Aerogel Composite with Superior Separation Performance for Organic Compounds
Yaping Zhao 1 , Huijun Tan 1 , Meng Meng Chai 1
1 School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai China
Show AbstractIn this work, we reported the fabrication of graphene-silica aerogel composite and its application in purification of Docosahexaenoic Acid Ethyl Esters (DHA-EE) from fish oil ethyl esters. The graphene-silica wet gel was firstly prepared by uniformly dispersing the pristine graphene exfoliated from graphite using supercritical CO2 technique into TEOS ethanol solution by sol-gel method. Then, the graphene-silica gel was dried to obtain the aerogel composite by supercritical CO2. The influence of aging and drying conditions on the structure, morphology and porosity of the graphene-silica aerogel composite was investigated. The as-prepared composite was characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, infra-red spectroscopy, and BET. The analysis results indicated that the composite had three-dimensional interconnected network with high specific surface area. The pristine graphene was highly dispersed in the silica aerogel matrix with holding maximum specific surface area. The as-prepared graphene-silica aerogel exhibited outstanding performance in purification of DHA-EE when it was utilized as sorbent in supercritical CO2 fractional column. More than 90% DHA-EE was obtained. The reason can be attributed to the combination of superior properties of silica aerogel and graphene. It suggests that the as-prepared composite has potential applications in separation process.
9:00 PM - NM3.5.09
Polysaccharide-Reinforced Silica Aerogels
Zoran Novak 1 , Gabrijela Horvat 1 , Zeljko Knez 1
1 , University of Maribor, Maribor Slovenia
Show AbstractThe large industrial application of inorganic aerogels is often hampered by their poor mechanical properties. The highest drawback of silica aerogel is its extreme fragility and therefore some reinforcements are desired for the practical use of those materials. On the other hand, polysaccharide aerogels have been widely studied in the recent past. They often provide better mechanical properties compared to silica aerogels. Therefore the combination of both may result in special class of materials with advanced properties. Hybrid aerogels were prepared by mixing polysaccharide solution with silica precursor without ay additional cross-linker or catalyst. Various polysaccharides were used in order to compare the properties of final hybrid materials. The addition of silica polysaccharides significantly improved their structural properties, especially the drastic surface area increase. Moreover, the thermal properties were also highly improved. Hybrid aerogels showed great thermal resistance and low thermal conductivities, only slightly higher than that of pure silica aerogels. In conclusion, polysaccharide-silica aerogels, prepared by the novel method, show great perspective for the further research. Such advanced materials could be eventually, without doubt, even used commercially.
9:00 PM - NM3.5.10
New Strategy to Mechanically Reinforce Aerogel by In Situ Growing Nanofillers
Benxue Liu 1 , Xibin Yi 1 3 , Qichun Wang 1 , Wei Ju 1 , Jing Zhang 1 , Huili Fan 1 , Xiaodong Shen 2
1 , Advanced Materials Institute, Shandong Academy of Sciences, Jinan China, 3 , Shandong Key Laboratory for High Strength Lightweight Metallic Materials, Jinan China, 2 , State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing China
Show AbstractAerogel is a sort of porous matter in which air percolates through the three-dimensional networks assembled by coherent nanoparticles. Due to the extraordinary high porosity and large surface area, aerogel exhibits many unique properties, such as ultra low thermal conductivity, low dielectric constant and low index of refraction. However aerogel suffer from extreme fragility and poor mechanical strength which limit the practical application. Recently, our group developed a reinforced strategy by in situ growing nanofillers in the targeted aerogel matrix. Inorganic salts were added in sol and the nanofillers formed in gelation and aging process. The pores in gel with various sizes provide micro-containers for the growth of nanofillers. Owning to the confinement effect by the pore scale, the as grown nanofillers were compatible with the pores in size and can efficiently prevent the pores from collapse when were compressed. A series of nanofillers have been grown in different aerogel matrix. For example, Al
2O
3 nanofibers have been grown in C aerogel, the compressive strength was measured to be as high as 9.1 MPa [1]. The strength of SiO
2 aerogel reinforced by in situ grown ZrO
x nanofibers could be reached to 9.68 MPa [2]. The crystal growth of the nanofillers and the reinforced mechanism were studied. We believe that the strategy could be used as an efficient way to fabricate aerogel with promised mechanical strength.
[1] Y. Zhong, Y. Kong, X. Shen, S. Cui, X. Yi, J. Zhang. Microporous Mesoporous Mater., 2013, 172, 182-189.
[2] X. Yi, L. Zhang, F. Wang, X. Shen, S. Cui, J. Zhang, X. Wang. RSC Adv., 2014, 4, 48601-48605.
Corresponding author: Xibin Yi. E-mail:
[email protected]9:00 PM - NM3.5.11
Silica Aerogel Synthesized under Ambient Pressure Drying, without Surface Hydrophobitazion
Lorena Alvarez Contrera 1 , Beatriz Alejandra Garcia Torres 1 , Alfredo Aguilar Elguezabal 1
1 , Centro de Investigación en Materiales Avanzados, S.C., Chihuahua Mexico
Show AbstractSilica aerogel spheres were synthesized by a technique of dripping, making it feasible the scaling of this technology from lab to pilot plant process. The spheres were synthesized by sol-gel process, atmospheric drying and without surface modification step. Previously, it was believed that for the ambient pressure drying, it was necessary the utilization of surface modifying agents, which avoided the fracture and contraction of the aerogel.
By this process the size of produced spheres was controlled and the effect of the size of spheres on the integrity of spheres during ambient drying step was studied. The mechanical resistance of spheres to compression was determined in order to correlate this property with the capacity to maintain its integrity during ambient drying step.
KEYWORDS: Silica aerogel, Ambient pressure drying
Acknowledgments
We thank CONACYT for the support through grant 271649 for Laboratorio Nacional de Micro y Nanofluídica (LABMyN).
9:00 PM - NM3.5.12
Silica Aerogels Impregnated with Copper-Containing Nanoparticles—An Investigation of Three-Way Catalytic Ability
Ann Anderson 1 , Elizabeth Donlon 1 , Adam Forti 1 , Vinicius Silva 2 1 , Mary Carroll 1 , Bradford Bruno 1
1 , Union College, Schenectady, New York, United States, 2 , Scotia-Glenville High School, Scotia, New York, United States
Show AbstractCopper-alumina and copper-silica aerogels formed by impregnation of a copper salt into an alumina or silica wet gel before supercritical extraction contain copper in multiple oxidation states: Cu, Cu2O and CuO [1]. These aerogels are effective at catalyzing the reduction of NO and the oxidation of HCs and CO under conditions similar to those found in automotive three way catalysts [2]. In this work we have incorporated Cu, Cu2O and CuO nanoparticles into silica aerogels to measure their individual contributions to the overall catalytic effectiveness. Nanoparticles in the form of (a) copper nanorods (100 nm diameter, 10-20 μm length); (b) Cu2O nanoparticles (350 nm diameter); or (c) CuO nanoparticles (25-55 nm diameter) were added (0.5-15% by weight) to separate precursor mixtures consisting of tetramethylorthosilcate, methanol, water and ammonia. These precursor mixtures were then processed using a rapid supercritical extraction method [3, 4] to form aerogels. The resulting aerogels show evidence of nanoparticles/rods dispersed throughout the silica aerogel structure. The aerogels were characterized to determine density (0.08-0.09 g/mL), surface area (200-300 m2/g), X-ray diffraction patterns, and catalytic ability. This presentation will focus on gaining an understanding how the copper oxidation state affects catalytic aerogel properties.
[1] Carroll MK, Anderson AM & Bruno, BA, 2016, “Catalytic Aerogels Prepared via Rapid Supercritical Extraction: Fabrication and Characterization” Presentation 1-B4, 3rd International Seminar on Aerogels, Sept 23-23, Sophia Antipolis (France).
[2] Bruno BA, Anderson AM, Carroll MK, Swanton T, Brockmann P, Palace T & Ramphal IA, 2016, “Benchtop Scale Testing of Aerogel Catalysts: Preliminary Results,” SAE Technical Paper No. 2016-01-0920.
[3] Gauthier BM, Bakrania SD, Anderson AM & Carroll MK, 2004, “A Fast Supercritical Extraction Technique for Aerogel Fabrication.” J. Non-Crystalline Solids, 350, 238-243.
[4] Carroll MK, Anderson AM, & Gorka CA, 2014 “Preparing Silica Aerogel Monoliths via a Rapid Supercritical Extraction Method.” J. of Visualized Experiments, 84, DOI: 10.3791/51421.
9:00 PM - NM3.5.13
Preparation and Structural Analysis of Magnesium Oxide Aerogels
Jiankai Zhang 1 , Xiaohong Chen 1 , Ran Liu 1 , Huaihe Song 1 , Zhihong Li 2
1 , Beijing University of Chemical Technology, Beijing China, 2 , Chinese Academy of Sciences, BeiJing China
Show AbstractMagnesium oxide aerogels were made by sol-gel process using magnesium methoxide as precursor，methanol and deionized water as solvent followed by supercritical drying with respect to ethanol. The influences of the different factors on the gel time and the specific surface area of magnesium oxide aerogels were studied, and the structure and morphology were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and X-ray diffraction (XRD). Furthermore, the Small Angle X-ray Scatter (SAXS) was utilized to determine the fractural structure of the magnesium oxide aerogels. The results showed that MgO aerogels belonged to typical mesoporous materials with rich network and highly developed pore structure, and the maximum specific surface area was 904.9 m2/g, the density was about 0.055 g/cm3, the average pore size was 19.6 nm. The results of SAXS analysis showed that the fractal dimension of the MgO aerogels was 2.32 in high q area which proved the existence of rough surface, and the pore size distribution calculated by SAXS was consistent with BET test.
9:00 PM - NM3.5.14
Applications for Oleophilic Hydrophobic Graphite Sponges
Fabian Villalobos 1 , Andrew Patalano 1 , Daisy Patino 1 , Cengiz Ozkan 1 , Mihri Ozkan 1
1 , University of California Riverside, Grand Terrace, California, United States
Show AbstractOleophilic hydrophobic graphite sponges have been grown which feature metal
nanoparticles embedded in a mesoporous carbon network (M = Li, Na, Al, K, Fe, Co, Ni, Cu,
Ag). The highly porous structure of this material has the potential to be utilized for catalysis,
used as a growth substrate, and separation of oils and non-polar solvents from water.
Antibacterial and ferromagnetic properties of the graphite sponges can be tuned by the choice of
metal and carbon network precursors. Carbon matrix can be separated from metal particles by
acid washing and filtration to be utilized as carbon material in cathodes and anodes for use as
electrochemical conducting additives. These applications are the result of environmentally
benign and low cost precursors such as carbohydrate sugars and poly(vinyl) alcohol. The porous
structures and compositions of these sponges were characterized via BET, SEM, FTIR, XRD,
and TEM.
9:00 PM - NM3.5.15
Fast Synthesis of Spherical Silica Aerogel Powders via Emulsion Polymerization from Waterglass
Kyoung-Jin Lee 1 , Haejin Hwang 1
1 , INHA University, Incheon Korea (the Republic of)
Show AbstractA silica aerogel is an ultra-porous material containing more than 90 % pores with a highly cross-linked network structure. The silica aerogel has unique properties such as large specific surface area, low thermal conductivity, low dielectric constant, low index of refraction, and so on. Owing to these unique properties, such aerogels have been studied extensively for use as catalysts and thermal insulators, and in applications related to adsorption, and drug delivery systems.
Silica aerogels can be fabricated in the form of a powder, monolith, blanket, and so on. Among these forms, the powder-type silica aerogel is thought to be the most promising because the powder can be applied to a wide field of applications. However, an aerogel powder with a fine particle size is hard to handle since it has a high apparent density and a low flowability. In this regard, much attention has been focused on granule- or bead-type silica aerogels. Until recently, silica aerogel granules or beads from hydrogels or alcogels were mainly synthesized by breaking down the wet gel using a high power mixer or by dropping a silica sol into an aqueous solution containing a gelation catalyst. However, these techniques make it difficult to obtain spherical aerogel granules or beads with a controlled particle size and microstructure.
In this study, a novel synthesis technique was proposed to fabricate spherical silica aerogel powders via one-pot surface modification(SM)/solvent exchange(SE) and the subsequent ambient pressure drying (APD) from waterglass. We significantly reduced the total processing time up to 2 to 3 hours, which normally takes 24 h or sometimes several days. The tap densities, particle sizes, and thermal conductivities of the spherical aerogel powders were measured and the processing parameters were discussed in terms of their effect on emulsion polymerization and SM/SE.
9:00 PM - NM3.5.16
Nanoporous Silica Aerogel Membranes for CO2 Capture
Yi-Feng Lin 1 , Jia-Wei Guo 1
1 , Chung Yuan Christian University, Taoyuan Taiwan
Show AbstractThe use of a membrane contactor combined with a hydrophobic porous membrane and amine absorbent has attracted considerable attention for the capture of CO2 due to its extensive use, low operational costs and low energy consumption. The hydrophobic porous membrane interface prevents the passage of the amine absorbent while allowing the penetration of CO2 molecules absorbed by the amine absorbent. Herein, for the first time, highly mesoporous and water-repellent SiO2 aerogels were successfully coated onto a macroporous Al2O3 membrane using different silanol precursors, such as tetraethyl orthosilicate (TEOS), methyltrimethoxysilane (MTMS) and bis(triethoxysilyl) ethane (BETES). The silica-based hydrophobic SiO2 aerogel membranes exhibited much higher CO2 absorption flux than the uncoated silica-based aerogel membranes and could be reused and continuously operated for CO2 absorption for extended periods of time. As a result, silica-based water-repellent aerogel membrane contactors are a promising technology for large-scale CO2 absorption post-combustion in power plants.
9:00 PM - NM3.5.17
The Effect of Embedded Nanoarchitectures on the Mechanical Properties of Silica Aerogels
Lucy Morgan 1 , Anna Corrias 1
1 , University of Kent, Canterbury United Kingdom
Show AbstractFor millions of years, nature has evolved nanoporous materials that combine high-strength with light-weight design (bone, crustacean shell etc.). More recently, nanoporous ceramics have been manufactured with framework architectures of nanometer dimensions.
With the aim to obtain new ultra-light ceramics with exemplary and tailored mechanical properties we are embedding nanoporous architectures in silica aerogel. To this end a variety of silica aerogel monoliths are being synthetized where we embed either templated mesoporous silica, such as SBA15, or nanoparticles such as CeO2 in a variety of shapes (i.e. cubes and spheres).
The morphological and structural properties are investigated via a multi-technique approach combining N2 physisorption at 77 K, transmission electron microscopy and X-ray diffraction, while the mechanical resilience to impact of the silica aerogel monoliths is tested by firing projectiles at the materials using the light gas gun (LGG) available at the University of Kent that can reach up to 7.5 km s-1.
9:00 PM - NM3.5.18
Preparation of Silica Aerogel and Its Properties as in Thermal Insulation Coating
Noppakun Sanpo 1 , Jaturong Jitputti 1
1 , SCG Chemicals Co., Ltd., Rayong Thailand
Show AbstractThe silica aerogel was prepared by a modified sol-gel method which gelation, aging, and silation processes were combined into one continuous step. The obtained silica aerogel was conducted for the thermal conductivity test and it showed the lower thermal conductivity data when compared with commercial product available in the recent market. In this research work, we also aim to replace the use of glass fiber in petrochemical industries by utilizing silica aerogel as a major component in thermal insulation coating and several properties of the achieved coating formulations will be studied and reported.
9:00 PM - NM3.5.19
Visible Light Induced Photocatalytic Hydrogen Evolution Using a CdS-Ni2P Hybrid Aerogel System
Da Li 1 , Stephanie Brock 1
1 , Wayne State University, Detroit, Michigan, United States
Show AbstractDue to the increasing global energy demand and the climate change impact of CO2 from energy production, it is essential to construct clean energy production and storage systems. Photocatalytic evolution of hydrogen from water utilizing visible light is a promising and appealing pathway. CdS nanoparticles are good visible light absorbers but not efficient hydrogen evolution catalysts, while Ni2P is shown to be an excellent electrocatalyst for the hydrogen evolution reaction (HER). Integration of CdS nanoparticles with Ni2P nanoparticles using sol-gel approach is expected to yield a hybrid system in which photo generated carriers on CdS are transferred to catalytically active Ni2P sites. In this work, the assembly of preformed nanoparticles to make Ni2P-CdS hybrid aerogels will be described and photocatalytic HER data will be presented. The performance of these novel architectures will be compared to CdS-Ni2P nanoparticles and CdS aerogels and the role of interparticle coupling and porosity on catalytic efficiency will be discussed.
Symposium Organizers
Stephen Steiner, MIT
Stephanie Brock, Wayne State University
Alexander Eychmueller, TU Dresden
Nicholas Leventis, Missouri University of Science and Technology
Symposium Support
Aerogel Technologies, LLC
Aspen Aerogels, Inc.
BASF Polyurethanes GmbH
Blueshift
JEOL USA, Inc.
NASA–Glenn Research Center
NM3.6: Frontier Aerogels I—Chalcogenides, Metals and Shaped
Session Chairs
Indika Arachchige
Alexander Eychmueller
Wednesday AM, April 19, 2017
PCC West, 100 Level, Room 105 BC
9:00 AM - *NM3.6.01
Platelets, Dots, Rods—Aerogelation of Shape-Controlled Nanocrystals
Nadja Bigall 1
1 , Physical Chemistry, Leibniz Universität Hannover, Hannover Germany
Show AbstractHydrogels, xerogels, cryogels and aerogels as novel macroscopic self-supporting networks of nanoparticle building blocks might help bridging the gap between the nanoscopic and the macroscopic world.
Our group is interested in the phenomena happening when assembling shape-controlled nanocrystals (resulting from colloidal nanoparticle synthesis) in such gel materials.[1-2] In certain cases, even new physical properties can result which are only present in the aerogel assembly and neither in the nanoparticle building block nor in bulk.[3] However, for each system investigated (platelets, rods, dots) and for each matter and respective surface chemistry, the gelation routes have to be adjusted in order to synthesize these monolithic ultralight materials with the desired properties, such as high photoluminescence quantum yields or the exhibition of controlled localized surface plasmon resonances. Therefore, in this talk, apart from chemical gelation routes, also a physical method for the synthesis of aerogels (the so-called cryoaerogelation route) will be presented, which is virtually independent on the substance, shape and surface composition of the nanoparticle building blocks employed.[4]
References:
[1]Photoluminescent Aerogels from Quantum Wells.
S. Naskar, J. F. Miethe, S. Sánchez-Paradinas, N. Schmidt, K. Kanthasamy, P. Behrens, H. Pfnür, N. C. Bigall, Chemistry of Materials 2016, 28, 2089–2099.
[2]Catalytic Properties of Cryogelated Noble Metal Aerogels.
A. Freytag, M. Colombo, N. C. Bigall, Zeitschrift für Physikalische Chemie 2016 DOI 10.1515/zpch-2016-0856.
[3]Aerogels from CdSe/CdS Nanorods with Ultra Long Exciton Lifetimes and High Fluorescence
Quantum Yields.
S. Sánchez-Paradinas, D. Dorfs, S. Friebe, A. Freytag, A. Wolf, N.C. Bigall, Advanced Materials 2015, 27 (40), 6152–6156.
[4]Versatile fabrication method for aerogels by freezing and subsequent freeze-drying of colloidal nanoparticle solutions.
A. Freytag, S. Sánchez-Paradinas, S. Naskar, N. Wendt, M. Colombo, G. Pugliese, J. Poppe, C. Demirci, I. Kretschmer, D.W. Bahnemann, P. Behrens, N.C. Bigall, Angewandte Chemie International Edition 2016, 55, 1200-1203.
9:30 AM - NM3.6.02
Programmable Assembly of Nanoparticles into Multicomponent Aerogels
Jessica Davis 1 , Stephanie Brock 1
1 , Wayne State University, Detroit, Michigan, United States
Show AbstractEffective exploitation of nanoparticles for applications in energy conversion (e.g., photovoltaics) and heterogenous catalytic processes requires the ability to assemble a variety of dissimilar components into a single architecture, and to do so in a way that enables facile interparticle communication as well as access to the individual components. Sol-gel methodologies represent a powerful approach for the assembly of nanoparticles into a variety of desirable architectures, from 2-D thin films to aerogels with 3-D interconnected matter-pore networks. Although sol-gel methodologies have traditionally been applied to oxides, we have pioneered work showing that metal chalcogenides can also be assembled into single-component thin films and aerogels by a process of oxidative chalcogenide linking, and this process has been applied to form a wide range of single component aerogels (e.g., CdS, PbTe, etc.). In this presentation, the parameters effecting chalcogenide gelation rates in single component systems will be evaluated and exploited for programmable assembly of aerogels comprising two distinct metal chalcogenide nanoparticles. We will show that control of the rate in single component systems can be used to produce multicomponent aerogels with varying degrees of heterogeneity, and hence, tunable functionality.
9:45 AM - NM3.6.03
Understanding the Formation of Low-Density, Linker-Mediated All-Inorganic Semiconductor Nanocrystal Aerogels
Amita Joshi 1 , Ajay Singh 1 , Delia Milliron 2
1 , Los Alamos National Lab, Los Alamos, New Mexico, United States, 2 Chemical Engineering, University of Texas at Austin, Austin, Texas, United States
Show AbstractThe aerogels have found application in a variety of areas, as nanoporous thermal insulators, for water purification, and catalysis, due to their inherent open, porous structure and high surface areas. Gels and aerogels built from a variety of metal and semiconductor nanoparticles have recently been demonstrated to provide such an opportunity. These highly porous solids have shown to keep the important properties of the nanoparticles that are used as building blocks. One strategy to form such aerogels is to mediate attractions between the semiconductor nanocrystal with negatively charged inorganic surface ligands via a linker species, e.g., a cation that is coordinated by negatively charged surface ligands. The resulting wet gel networks are therefore composed of purely of inorganic semiconductors with simple and tunable chemical components. A variety of low-density all-inorganic gels have been formed experimentally from nanocrystals using this strategy, but how to control the physical properties of these gels is not well understood in general. The attraction between the surface ligands and linker species results in clustering, gelation and aggregation depending upon the linker concentration. By using small angle X-ray scattering, we are able to differentiate between these different stages and better understand the process of gel formation. We are also studying the thermo-reversible nature of these gels using the SAXS technique. Here we discuss, the understanding of the fundamental phenomena related to the mechanisms of inorganic aerogel formation via mediator, the interactions between the nanoparticles, and the effect of linker attractions on different phase behavior of wet gels.
10:00 AM - NM3.6.04
Shape-Engineering of the Building Blocks in Multimetallic Hierarchical Aerogels
Bin Cai 1 , Alexander Eychmueller 1
1 Physical Chemistry, TU Dresden, Dresden Germany
Show AbstractAerogels assembled from colloidal nanocrystals are of enormous scientific and technological interest owing to their ultralow density, high surface area and large open interconnected pores.[1] Over the past decade, various kinds of nano building blocks (NBBs), varying from semiconductors, metal oxides, metals, etc., have been employed to design aerogel monoliths and explore their improved properties.[2-4] The aerogels built from the NBBs can inherit the properties and functions from the parent NBBs while maintaining the aerogel properties, which frequently leads to amplification of the inherited properties and results in features that are unique to the aerogels. Nonetheless, the investigation of aerogel electrocatalysts is still in the early stages and is largely limited by the solid NBBs and simplified compositions. Thus, it holds great promise to endow aerogel electrocatalysts with improved catalytic properties by optimizing the metal NBBs in terms of morphology and alloying.
This presentation will report our recent progress on the in-situ shape engineering of NBBs in multimetallic hierarchical aerogels. Starting from alloyed PdNi hollow nanospheres (HNS) as the building blocks, the resulting PdNi HNS aerogels combine the advantages of the aerogel structure, the hollow interior and an alloying effect and show an up to 5.6- and 4.2- fold improved mass and specific activity for ethanol oxidation reaction (EOR), respectively, as compared to Pd/C.[7] By tuning the compositions, the morphology of the NBBs was in-situ engineered from hollow nanospheres to dendritic nanocrystals. This results in aerogels with hierarchical structures organizing the nanoscale regulated architecture and macroscale three-dimensional network structure, leading to an abundance of exposed edges and a high surface area (varying from 95.4 to 67.7 m2 g1 for different compositions). With the aid of time-dependent transmission electron microscopy and first principle molecular dynamics simulations, the structural growth mechanism was revealed in terms of nanowelding of the particulate reaction intermediates. Thanks to the joint hollow-dendritic morphologies, the hierarchical aerogels exhibit a remarkable electrocatalytic activity which is 10.6 and 7.6-fold higher than the Pd/C and Pt/C catalysts, respectively, taking EOR as an example.[6]
References
[1] J. L. Mohanan, I. U. Arachchige, S. L. Brock, Science 2005, 307, 397.
[2] N. Leventis, N. Chandrasekaran, A. G. Sadekar, C. S. Leventis, H. Lu, J. Am. Chem. Soc., 2009, 131, 4576.
[3] I. U. Arachchige, S. L. Brock, Acc. Chem. Res. 2007, 40, 801.
[4] N. C. Bigall, A. K. Herrmann, M. Vogel, M. Rose, P. Simon, W. Carrillo-Cabrera, D. Dorfs, S. Kaskel, N. Gaponik, A. Eychmüller, Angew. Chem. Int. Ed. 2009, 48, 9731.
[5] B. Cai, D. Wen, W. Liu, A. K. Herrmann, A. Benad, A. Eychmüller, Angew. Chem. Int. Ed. 2015, 54, 13101.
[6] B. Cai, A. Dianat, R. Hübner, W. Liu, D. Wen, A. Benad, L. Sonntag, T. Gemming, G. Cuniberti, A. Eychmüller, Adv. Mater. 2017, DOI: 10.1002/adma.201605254.
10:15 AM - NM3.6.05
Synthesis and Characterization of Ceria Cuboidal Nanoparticles Stabilized into a Silica Aerogel Matrix
Francesco Caddeo 1 , Danilo Loche 2 , Maria Casula 2 , Andrea Falqui 3 , Efisio Zuddas 3 , Anna Corrias 1
1 , University of Kent, Canterbury United Kingdom, 2 , University of Cagliari, Cagliari Italy, 3 , King Abdullah University for Science and Technology, Tuwal Saudi Arabia
Show AbstractNanoceria plays a central role in many applications such as catalysis[1], solid oxide fuel cells[2], solar cells[3] and oxygen storage materials[4]. In terms of catalysis, the rational control of the shape of ceria nanoparticles has acquired great importance due to the difference in reactivity depending on the surface exposed[5]. In particular, nanoparticles with cuboidal shape showed an increased catalytic activity due to the most reactive {100} exposed surface[6]. In order to reach synthetic control over the shape of the nanoparticles, procedures involving the use of capping agents have been developed[7]. However, capping agents stay bounded at the surface of the nanoparticles limiting its reactivity; furthermore ceria nanoparticles easily aggregate under thermal treatments, leading to a decrease in the surface area and therefore in their reactivity[6].
We have successfully stabilized cuboidal and polyhedral CeO2 nanoparticles into a SiO2 aerogel matrix. Once the nanoparticles are embedded in the aerogel, the capping agent bounded at the surface of the nanoparticles is easily eliminated by thermal treatment avoiding the problem of the aggregation due to the aerogel matrix that keeps the nanoparticles apart.
The exceptional thermal stability of the obtained CeO2-SiO2 nanocomposites that combine enhanced CeO2 surface reactivity with the extraordinary properties of aerogels in terms of surface area and open porous network, make them extremely attractive as heterogeneous catalysis.
References:
1 Ta N.; Liu J.; Shen W. Tuning the shape of ceria nanomaterials for catalytic applications. Cuihua Xuebao/Chinese J. Catalysis, 2013, 34, 838-850.
2 Malvasi L.; Fisher C. A. J.; Islam M. S. Oxide-ion and proton conducting electrolyte materials for clean energy applications: structural and mechanistic features. Chem. Soc. Rev., 2010, 39, 4370–4387;
3 Corma A.; Atienzar P.; García H.; Chane-Ching J. Y. Hierarchically mesostructured doped CeO2 with potential for solar-cell use. Nature Materials, 2004, 3, 394-397.
4 Di Monte R.; Kašpar J.; Bradshaw H.; Norman C. A rationale for the development of thermally stable nanostructured CeO2-ZrO2-containing mixed oxides. Journal of Rare Earths, 2008, 26, 136-140.
5 Na, T.A., LIU, J. and Wenjie, S.H.E.N., 2013. Tuning the shape of ceria nanomaterials for catalytic applications. Chinese Journal of Catalysis, 2013, 34(5), pp.838-850.
6 Zhang, J., Kumagai, H., Yamamura, K., Ohara, S., Takami, S., Morikawa, A., Shinjoh, H., Kaneko, K., Adschiri, T. and Suda, A., 2011. Extra-low-temperature oxygen storage capacity of CeO2 nanocrystals with cubic facets. Nano letters, 2011, 11, pp.361-364.
7 Yang, S. and Gao, L., 2006. Controlled synthesis and self-assembly of CeO2 nanocubes. Journal of the American Chemical Society, 2006, 128, pp.9330-9331.
10:30 AM - NM3.6.06
Ultra-Low Density Nanoporous Silver Foams via Freeze-Casting of Nanowires
Tyler Fears 1 , Jeffrey Colvin 1 , Sergei Kucheyev 1
1 , Lawrence Livermore National Laboratory, Livermore, California, United States
Show AbstractUltra-low density (<20 mg/cm3) nanoporous materials that can be formed into monolilthic objects with well-defined macroscopic dimensions are desirable for a number of niche application, yet are frustratingly difficult to fabricate. The few materials that can be fabricated to these specifications (e.g., SiO2, Fe2O3, C) often require complex, multistep syntheses and/or highly specialized equipment. Here, we describe a facile method for fabricating ultra-low density monolithic Ag foams via freeze-casting of Ag nanowire suspensions followed by supercritical drying. Resultant foams have densities down to 6 mg/cm3. They are uniform and mechanically robust. Since this fabrication method is primarily physical in nature, it can be applied in principle to a broad range of materials. This work was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.
10:45 AM - NM3.6.07
Direct Solution-Based Reduction Synthesis of Au, Pd, and Pt Aerogels
John Burpo 1 , Stephen Winter 1 , Jesse Palmer 1
1 , United States Military Academy, West Point, New York, United States
Show AbstractNoble metal aerogels possess high surface area and tunable porosity for a wide range of catalytic, sensing, and energy applications. Few techniques present a direct synthesis route to achieving aerogel structures. Here we present the synthesis of gold, palladium, and platinum gels using direct solution based reduction of precursor salt solutions using range of reducing agents. No other chemicals were used. Final aerogel structures were achieved using super critical point drying. Material characterization was performed using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffractometry, atomic force microscopy nano-indentation, and cyclic voltammetry. The resulting 3-dimensional, contiguous aerogel structures showed a dependence on the concentrations of both salt and reducing agent solutions. After supercritical point drying, each noble metal aerogel also presented unique structural morphologies for a given reducing agent. Gold aerogels presented smoother, elongated wire-like elements; palladium aerogels presented rough, fused particles; and platinum aerogels presented rough, elongated wire-like elements. Nobel metal aerogel element diameters ranged from approximately 10 to 100nm depending on synthesis conditions. Gels were also able to be mechanically pressed into films and dried at ambient temperature. The resulting pressed films retained the structural features of supercritically dried aerogels, but with a significant decrease in both volume and porosity. These self-supporting aerogels and aerogel films synthesized via a single reduction step are envisioned to offer a flexible synthesis scheme to tune porosity, surface area, and mechanical robustness for noble metal catalytic, sensing, and energy applications.
NM3.7: Frontier Aerogels II—Metals
Session Chairs
Nadja Bigall
Nicholas Leventis
Wednesday PM, April 19, 2017
PCC West, 100 Level, Room 105 BC
11:30 AM - *NM3.7.01
Noble Metal Aerogels—From Model Studies to Polymer Electrolyte Fuel Cell Performance
Thomas Schmidt 1 2
1 Electrochemistry Laboratory, Paul Scherrer Institute, Villigen Switzerland, 2 Laboratory of Physical Chemistry, ETH Zurich, Zurich Switzerland
Show AbstractState-of-the-art polymer electrolyte fuel cells (PEFCs) require large amounts of carbon-supported platinum nanoparticle (Pt/C) catalysts (~ 0.4 mgPt/cm2geometric) to account for the large overpotential of the oxygen reduction reaction (ORR). [1] These excessive Pt-loadings that impede widespread commercialization of PEFCs can be mitigated by increasing the catalysts’ ORR activity, e.g. by alloying platinum with other metals like Ni, Cu and Co, to form materials which show up to one order of magnitude higher mass-specific activity than commercial Pt/C catalysts. On the other hand, state-of-the art carbon-supported materials suffer from significant carbon and Pt corrosion during the normal operation of PEFCs, gradually compromising their performance. To partially overcome these stability issues, a lot of research effort is dedicated to the development of unsupported ORR catalysts. Among these materials, bimetallic alloy aerogels consisting of nanoparticles interconnected to nanochains [2] present an interesting option, since their extended 3D structure should facilitate transfer to actual PEFC cathodes.
In this talk, after having elucidated the high electrocatalytic activity of noble metal aerogels towards the ORR in model studies [3], the successful transfer of these catalysts into technical PEFC cathode environment will be presented demonstrating the practical applicability of these systems.
[1] A. Rabis, P. Rodriguez, T.J. Schmidt, ACS Catalysis 2 (2013) 768-800.
[2] W. Liu, A.-K. Hermann, N.C. Bigall, P. Rodriguez, D. Wen, M. Oezaslan, T.J. Schmidt, N. Gaponik, A. Eychmüller, Acc. Chem. Res. 48 (2015) 154-162
[3] S. Henning, L. Kühn, J. Herreanz, J. Durst, T. Binninger, M. Nachtegaal, M. Werheid, W. Liu, M. Adam, S. Kaskel, A. Exchmüller, T.J. Schmidt, J. Electrochem. Soc. 163 (2016) F1-F6
12:00 PM - NM3.7.02
Bimetallic Pt-M (M=Ni, Cu, Co, Fe) Aerogels as Efficient Catalysts for Oxygen Reduction
Laura Kuehn 1 , Sebastian Henning 2 , Wei Liu 1 , Juan Herranz 2 , Thomas Schmidt 2 3 , Alexander Eychmueller 1
1 Physical Chemistry, TU Dresden, Dresden Germany, 2 Electrochemistry Laboratory, Paul Scherrer Institute, Villigen Switzerland, 3 Laboratory of Physical Chemistry, ETH Zürich, Zürich Switzerland
Show AbstractPolymer electrolyte membrane fuel cells (PEMFCs) constitute a promising emission-free technology for power generation. Due to the sluggish reaction kinetics of the oxygen reduction reaction (ORR) at the cathode, efficient catalysts are required. Despite large efforts in research to develop such materials, high cost, low stability and insufficient catalytic activity still remain critical issues. Significant increase in activity compared to commercial Pt/C catalysts was reached by alloying platinum with other metals like Ni, Cu and Co.1 However, state-of-the-art carbon supported materials suffer from severe carbon and platinum corrosion.
Metallic aerogels are excellent candidates to overcome these issues, as they do not employ any catalyst support. Based on a previously published synthesis for Pt-Pd aerogels,2 we developed a facile one-step procedure to obtain Pt-M (M=Ni, Cu, Co, Fe) aerogels at ambient conditions in aqueous solution.
The materials possessed a highly porous structure with large specific surface areas. Both metals formed an alloy as proven by powder X-ray diffraction (XRD). X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) indicated the presence of oxidic phases in aerogels with higher contents of the non-noble metal (1:1 composition) whereas Pt3M aerogels were primarily metallic. Local elemental distribution was analyzed by scanning transmission electron microscopy with energy dispersive X-ray spectroscopy (STEM-EDX). Pt3Ni and PtCu aerogels showed excellent ORR activity, reaching the target of 440 A/gPt at 0.9 VRHE set by the U.S. Department of Energy3 for automotive PEMFCs.
In conclusion, we developed a facile one-step synthesis route for alloyed Pt-M (M=Ni, Cu, Co, Fe) aerogels. Pt-Ni and Pt-Cu aerogels were excellent ORR catalysts.
1. Wang, C. et al. Design and synthesis of bimetallic electrocatalyst with multilayered Pt-skin surfaces. J. Am. Chem. Soc. 133, 14396–14403 (2011).
2. Liu, W. et al. Bimetallic Aerogels: High-Performance Electrocatalysts for the Oxygen Reduction Reaction. Angew. Chemie Int. Ed. 52, 9849–9852 (2013).
3. The US Department of Energy. Technical Plan - Fuel Cells. Multi-Year Research, Development and Demonstration Plan (2012). Available at: www.eere.energy.gov/hydrogenandfuelcells/mypp/pdfs/fuel_cells.pdf. (Accessed: 29th September 2016)
12:15 PM - NM3.7.03
3D Ordered Nanostructured Ferromagnetic and Electronic Metal Metalattices Synthesized from Mesoporous Templates—High Pressure Chemical Deposition, Surface Modification and Confinement-Induced Physical Properties
Yunzhi Liu 2 , Susan Kempinger 1 , Shih-Ying Yu 3 , Parivash Moradifar 3 , Jennifer Russell 2 , Vincent Torres 2 , Thomas Mallouk 2 1 , Nasim Alem 3 , Suzanne Mohney 3 , Nitin Samarth 1 , Venkatraman Gopalan 3 , John Badding 2 1 3
2 Chemistry, The Pennsylvania State University, University Park, Pennsylvania, United States, 1 Physics, The Pennsylvania State University, University Park, Pennsylvania, United States, 3 Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States
Show AbstractMetalattices are artificial nanostructured solids of 3-D order with periods between 1 nm – 100 nm.[1, 2] When a metal is confined in such a geometry, the intrinsic electron mean free path and magnetic characteristic length are at the same length-scale as the periodicity. Thus the interaction between the intrinsic physical parameters with the structural parameters can lead to novel magnetic, electric and thermal phenomena.[2, 3]
One way to fabricate such metalattices is to infiltrate metals into the voids and necks of mesoporous silica templates,[4] forming meta-atoms[5] which are analogous to nanoparticles, but are connected with one another by meta-bonds (necks) capable of transporting electrons and connecting magnetic vortices throughout the structure.
Here, we report the templated synthesis of 3-D nanostructured metalattices made of different metals and with a variety of structural periodicities. We use high pressure[6] supercritical fluid chemical deposition[7] (high pressure SFCD), which has template-independent infiltration capability. Compared to planar film deposition, the space control of the reactor is crucial to guarantee the deposition in nanoscale voids and necks. For some metals, an extra step of modifying the silica inner-surface is needed prior to the metal deposition, in order to improve the quality of the film coating and network formation.
Magnetometry of ferromagnetic nickel metalattices shows both confinement-induced and network-connection-induced magnetic behavior, suggesting that these metalattices have novel properties that differ from those of both bulk planar films and separately-dispersed nanoparticles.
This work was funded by the Penn State MRSEC, Center for Nanoscale Science, under the award NSF DMR-1420620.
[1] Annu. Rev. Mater. Sci. 2000, 30, 545.
[2] a) Phys. Rev. Lett. 2001, 86, 696; b) Phys. Rev. Lett. 2002, 89, 197203.
[3] Nature 2006, 439, 303.
[4] a) Phys. Rev. B 2000, 62, 2780; b) Langmuir 2008, 24, 1714; c) J. Colloid Interface Sci. 2011, 360, 1; d) J. Cryst. Growth 2004, 267, 317.
[5] Annu. Rev. Phys. Chem. 1998, 49, 371.
[6] a) Science 2006, 311, 1583; b) Adv. Mater. 2010, 22, 4605; c) J. Am. Chem. Soc. 2011, 134, 19; d) Adv. Mater. 2016. DOI:10.1002/adma.201600415.
[7] a) Chem. Mater. 2000, 12, 2625; b) Chem. Rev. 2009, 110, 459; c) J. Supercrit. Fluids 2007, 41, 179. d) Science 2001, 294, 141; e) Adv. Mater. 2003, 15, 316.
12:30 PM - *NM3.7.04
Oxidation-Induced Self-Assembly of Metal Nanoparticles into High Surface Area, Electrically Conducting Nanostructures—Noble Metal Aerogels
Lamia Nahar 1 , Xiaonan Gao 1 , Indika Arachchige 1
1 , Virginia Commonwealth University, Richmond, Virginia, United States
Show AbstractThe assembly of nanoscale materials into functional superstructures is an important challenge that needs to be addressed for the generation of nanoparticle-based devices. Sol-gel method has proved useful for the direct-assembly of metal, semiconductor, and their hybrid nanoparticle systems into high surface area, highly conducting, mesoporous nanostructures (aerogels). In contrast to traditional metal oxide sol-gel synthesis, where gelation is achieved through hydrolysis and condensation of molecular precursors, the gel formation in nanoparticle-based systems is induced through oxidative removal of surfactant ligands from pre-formed colloidal nanoparticles. In this study, the application of the later strategy for the self-assembly of binary and ternary metal nanoparticles into metallic aerogel superstructures is described in the context of their use in electrocatalysis. The effect of synthetic parameters on the primary particle size, morphology, electrical conductivity, optical transparency and opacity, surface area and porosity will be discussed in light of application in chemical sensing and heterogeneous catalysis.
NM3.8: Functional Aerogels for Sensors and Catalysts
Session Chairs
Stephanie Brock
Barbara Milow
Wednesday PM, April 19, 2017
PCC West, 100 Level, Room 105 BC
2:30 PM - NM3.8.01
Protein Nanofiber Gold Aerogels—Properties and Applications
Gustav Nystroem 1 , Maria Fernandez-Ronco 1 2 , Sreenath Bolisetty 1 , Aurel Radulescu 3 , Marco Mazzotti 1 , Raffaele Mezzenga 1
1 , ETH Zurich, Zürich Switzerland, 2 , Empa, St Gallen Switzerland, 3 , Jülich Centre for Neutron Science (JCNS) at MLZ, Forschungszentrum Jülich GmbH, Garching Germany
Show AbstractTraditionally prepared aerogels from silica or metal oxides are inherently brittle. This leads to fracture and loss of both material and material properties, thereby limiting the aerogels' application range. One way to broaden the use of aerogels, through improved mechanical flexibility, is to form the precursor gels from flexible high aspect ratio organic colloids.[1–3] The colloidal approach also allow to transfer properties of the colloids on the nanoscale to the macroscale material. This gives the aerogel functional properties and enables design of optical, electronic and catalytic properties. We recently proposed a new class of aerogel materials based on colloidal protein nanofibers, so called amyloid fibrils.[4]
In this contribution I will show a colloidal approach to combine amyloid fibrils with gold nanoparticles and microcrystals to form protein gold hybrid aerogels. The aerogels, prepared from water dispersion, physical gelation and supercritical CO2 drying, were analyzed using electron and light microscopy, thermogravimetric analysis, nitrogen sorption and contrast matching neutron scattering. I will describe how the properties of these aerogels can be tuned by the size, shape and mass fraction of the gold particles, how the aerogels can be used in sensing and catalysis applications as well as discuss future possibilities for colloidal protein based aerogels.
References
[1] M. B. Bryning et al., Adv. Mater. 19, 661 (2007)
[2] H. Hu et al., Adv. Mater. 25, 2219 (2013)
[3] Y. Kobayashi et al., Angew. Chem. Int. Ed. 53, 10394 (2014)
[4] G. Nyström et al., Adv. Mater. 28, 472 (2016)
2:45 PM - NM3.8.02
Effects of Interfacial Design in Au–TiO2 and Cu–TiO2 Plasmonic Aerogels for Visible Light–Driven Photocatalysis
Debra Rolison 1 , Paul DeSario 1 , Jeremy Pietron 1 , Evan Glaser 1 , James Yesinowski 1 , Todd Brintlinger 1 , Rhonda Stroud 1
1 , U.S. Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractAerogels afford an opportunity unique within heterogeneous catalytic science: the tunable materials/catalysis platform—and agglomeration-free one at that—allows one to correlate catalytic activity to an interfacial arrangement of catalytic nanobit and comparably sized oxide network. The hierarchical nature of aerogels innately amplifies the number of three-phase boundaries, plumbs molecular conduits in three dimensions (3D), and wires electrical transport inherent to catalytic processes into the 3D-interconnected solid nanoscopic networks [1]. The nature of the interfacial junction between 5-nm Au guests and the ca. 10-nm TiO2 network affects the efficacy of plasmonically driven photo-oxidation of water, with a surface area–normalized 1.6× increase in activity when the Au guest is sited “in” rather than “on” the nanoparticulate TiO2 network [2]. This arrangement of Au and oxide also affects the number of defect sites present in the catalytic nanoarchitecture as discerned by 1-H nuclear magnetic and electron spin resonance spectroscopy. The intimate, 3D intermingling of metal nanoparticle and oxide network has now been shown to ensure that supported Cu nanoparticles remain sufficiently oxide-free to exhibit a plasmonic response, even during visible–light stimulated photocatalytic oxidations [3]. The resulting comprehensive mechanistic understanding derived from these studies will inform the design of next-generation catalytic architectures that provide superior performance.
[1] D.R. Rolison, Science 2003, 299, 1698.
[2] P.A. DeSario, J.J. Pietron, D.E. DeVantier, T.H. Brintlinger, R.M. Stroud, D.R. Rolison, Nanoscale 2013, 5, 8073.
[3] J.J. Pietron, P.A. DeSario, D.R. Rolison, T.H. Brintlinger, R.M. Stroud, U.S. Provisional Application, 29 March 2016.
3:00 PM - NM3.8.03
Monolithic High Li- and B-Content Aerogels—Lithioborates, Lithiosilicates, Lithioborosilicates and Non-Oxide Lithium Boron, Lithium Boron Carbide and Lithium Boron Silicon Carbide
Stephen Steiner 1 , Benjamin Wunsch 1 , Adam Visentin 1 , Ryan Nelson 1 , Justin Griffin 1
1 , Aerogel Technologies, LLC, Boston, Massachusetts, United States
Show AbstractFrom high-energy-density batteries to 3He replacements, Li and B are important elements for which the high-surface-area and high-porosity morphologies of aerogels would be highly desirable form factors towards production of advanced battery media, solid-state neutron detectors, and high strength-to-weight ratio multifunctional composites. Brinker and Weinberg explored borate aerogel synthesis in the 1980s showing the importance of using Li+ to stabilize the borate network, however stable monolithic aerogels and high-Li-concentration lithioborates remained elusive, in part because of precipitation of the reactive alkoxides by water needed to form the gels. We prepared monolithic aerogels with high Li and/or B concentrations of lithioborate, other alkali- and alkaline-earth-doped borate, lithiosilicate, and lithioborosilicate compositions as well as reduced non-oxide aerogel compositions of lithium boron, lithium boron carbide, and lithium boron silicon carbide. Borate wet gels with Li:B molar ratios (x) of 0.2-0.7 were prepared and dried supercritically from CO2. The resulting opaque white aerogel monoliths underwent virtually no volume loss compared to their wet gels with densities ranging from 0.06-0.5 g/cm3 but were weaker than silica aerogels. Notably, crack-free monolithic aerogels with Li:B ratios of 0.4-0.7, previously not reported, were successfully synthesized. A synthetic route eliminating precipitation and monolith cracking was established using MeOH and THF for the solvent system, a specific order of reagent introduction, and pin-hole moisture infiltration rather than direct addition of H2O. Density, surface area, and pore volume decreased while pore size increased with increasing x up to 0.6, reversing at 0.7. Divalent countercations gave higher densities but better stability against solvents/moisture than monovalent countercations. Monolithic lithiosilicate gels with Li:Si ratios of 0.1-0.7 were prepared and were more stable against pore fluid exchange into most solvents than lithioborates. The resulting aerogels had higher surface areas than lithioborates but were also fragile. Lithioborosilicate gels and aerogels with Li:B ratios of x=0.2-0.7 and B:Si~0.23 were synthesized and were stronger than lithioborates or lithiosilicates. All B- and Li-containing aerogels were sensitive to moisture to varying degrees. Lithiosilicate and lithioborosilicate aerogels were rendered stable against moisture by treatment of the wet gels with HMDS, which disintegrated lithioborate gels. All gels were stabilized against moisture by forming a polymer layer over the gel backbone using various triisocyanates, which also improved strength. Lithioborosilicate and lithioborate aerogels reinforced with an aromatic triisocyanate were pyrolytically smelted to give reduced lithium boron carbide and lithium boron silicon carbide aerogels with surface areas of 5-54 m2/g. Last, advanced shape control was used to make hierarchically porous functional components.
3:15 PM - NM3.8.04
Assembly of Tin-Doped Indium Oxide Nanocrystals into Three-Dimensional Plasmonic Gels via Depletion-Attraction Interactions
Camila Saez Cabezas 1 , Ryan Jadrich 1 , Gary Ong 1 , Thomas Truskett 1 , Delia Milliron 1
1 , The University of Texas at Austin, Austin, Texas, United States
Show AbstractOver the last decade, the assembly of semiconductor nanocrystals (NCs) into three-dimensional gel networks has advanced exciting avenues for designing next-generation optical and electronic materials. Remarkably, free-standing, highly porous, and macro-sized structures exhibiting quantum confined photoluminescence in the case metal chalcogenide NCs and plasmon resonance response for noble metals have been reported. Nonetheless, infrared plasmonic NC gel networks remain unexplored. In addition, current NC gelation methods rely on linker-mediated binding, which typically involves multi-step surface functionalization and specific linking chemistries (e.g., electrostatic, ion complexation, hydrogen bonding, hydrophobicity, etc). Developing a versatile and universal gelation strategy adaptable to any type of NC would provide a great opportunity to expand their applications beyond conventional optoelectronic devices, especially for doped metal oxide systems.
Herein, we introduce novel NC gels composed of charge-stabilized tin-doped indium oxide (ITO) building blocks that absorb light in the near-infrared region. To assemble these gels, we sought to develop a NC gelation strategy based on balancing short-range depletion-attractions and long-range electrostatic repulsions. This thermodynamically-controlled bonding strategy has been reported for polymer colloids and protein systems, but has not been previously adapted to NC systems. Since the parameters that govern depletion-attractions do not depend on NC composition or chemical affinity, we envision that our experimental results will serve as a modular model system suitable for a broad library of NCs and depletants.
We demonstrate such self-assembly for charge-stabilized ITO dispersions in acetonitrile in the presence of 1 kDa polyethylene glycol depletant. While mixtures containing low depletant concentrations resulted in free-flowing solutions of clusters, once a critical depletant concentration was reached, the solution formed a single-phase and transparent blue gel. Preliminary, UV-vis spectroscopy measurements revealed that these assemblies retained the original plasmonic response of the isolated ITO NCs. However, local NC arrangement influences the material’s optical properties due to plasmonic coupling interactions. To elucidate the relationship between gel structure and extrinsic optical properties, we characterized the network’s structural features and optical transmittance at various stages of the assembly. Small-angle x-ray scattering analysis revealed that under these conditions, the plasmonic clusters and gel exhibit a fractal dimension corresponding to linear and branched morphologies. Systematically understanding the structure-property relationship of this versatile gelation framework presents a promising avenue to predict the behavior of optically-active gels and thereby advance their integration into optoelectronic devices.
NM3.9: Environmental Remediation
Session Chairs
Thomas Schmidt
Stephen Steiner
Wednesday PM, April 19, 2017
PCC West, 100 Level, Room 105 BC
4:30 PM - *NM3.9.01
Polysaccharide Based Aerogels as Sustainable Absorbing Materials
Barbara Milow 1 , Philipp Niemeyer 1 , Kathirvel Ganesan 1
1 , DLR, Koeln Germany
Show AbstractPolysaccharides are the most abundant organic molecules on Earth. Since ancient times they are used as renewable sources for several products. The polymeric hydrocarbon molecules are composed on repeated glucose units which are easy to be chemically modified. Already slight modifications can change the chemical and physical properties such as water resistance or water solubility, or the affinity towards other chemicals like gaseous pollutants.
The nano-structured open-porous nature of aerogels provide important benefit for adsorbing materials. They deal with adjustable properties like huge surface areas, pore size distributions and pore volumes which provide high efficiency.
For filtering applications aerogels in shape of beads are of advantage to maximize adsorption capacity, tailor gaseous flowrates and enable the necessary diffusivity on the other hand.
Our investigations on the synthesis recipes and processing parameters lead to great improvement. Cellulose itself can be used as a humidity regulating absorber and the presence of amine groups of chitosan-based aerogels show a remarkable potential for the absorbance of CO2. Further applications can be achieved for the adsorption of volatile organic compounds by suitable modifications. The field of possibilities seems to be endless.
Meanwhile an available technical process for jelly beads, using a jet-cutter® unit, is laboratory tested for the production of aerogel beads.
Within the presentation the chemical synthesis and the preparation of various polysaccharide aerogels will be explained. In addition beads shaping techniques from lab scale to technical production will be discussed. Results on the characterization of the received beads, their morphology and physical as well as chemical properties will be shown. The determinations of the adsorption and desorption of selected gases will be evaluated to show its possibility to regenerate. The potential on aerogel beads for sustainable absorbing applications will be considered.
Part of this work has received funding from the European Union´s Horizon 2020 research and innovation program under grant agreement No 685648.
5:00 PM - NM3.9.02
Composite Aerogels for Water Remediation Applications
Maria Casula 1 , Danilo Loche 1 , Luca Malfatti 2 , Davide Carboni 2 , Valeria Alzari 2 , Alberto Mariani 2
1 , University of Cagliari, Cagliari Italy, 2 , University of Sassari, Sassari Italy
Show AbstractThe use of aerogels in environmental clean-up applications takes advantage of high surface area, extended porosity, as well as tunability of the surface properties of the aerogel material that can be used to absorb contaminants from water. Being a major environmental priority, oil recovery from oil-water mixtures due to oil spills or industrial wastewaters have been investigated. In particular, while pioneering work focused on the use of hydrophobic silica, the attention has been recently directed towards carbon-based aerogels.[1-5]
In this work, we prepare for the first time Graphene-SiO2 composite aerogels to combine the specific advantages of both phases in view of their prospective use as oil sorbents from contaminated water.[6]
We succeed in preparing a composite hydrophobic aerogel by co-gelation of low defectivity graphene sheets mainly made out of bilayers and silica, followed by high temperature supercritical drying. The physico-chemical features of the aerogels have been assessed by transmission and scanning electron microscopies (TEM and SEM), N2-physisorption at 77 K, contact angle measurements, wide-angle X-ray diffraction (XRD), thermal analysis techniques (TGA-SDTA), Raman and infrared spectroscopies.
We found that the introduction of graphene into silica, even at extremely low loadings (0.1 wt%) greatly improves the hydrophobic and oleophilic features of the silica aerogel. In agreement, the adsorption capacity, k, of both commercial and crude oil of the graphene-silica aerogel is significantly (20%) higher than for pure silica aerogel. Monitoring the clean-up process in an oil-water mixture with time shows that oil sorption takes place within the order of tens of seconds. As opposed to pure C-based aerogels, which to date exhibit the highest oil sorption capacities, a specific advantage of the developed composites is that they exhibit a relative fire-resistance, where burning represents a major threat connected to oil spills. We prospect that the design of novel carbon-silica composite aerogels will provide sorbents with improved properties for environmental remediation.
[1] S. Kabiri, D. N.H. Tran, S. Azari, D. Losic, ACS Appl. Mater. Interfaces 7 (2015) 11815-11823;
[2] L.W. Hrubesh, P.R. Coronado, J.H. Satcher Jr, J. Non-Cryst. Solids 285 (2001) 328-332;
[3] M.L. N. Perdigoto, R.C. Martins, N. Rocha, M.J. Quina, L. Gando-Ferreira, R. Patricio, L. Duraes, J. Coll. Int. Science 380 (2012) 134-140;
[4] S. Zhou, W. Jiang, T. Wang, Y. Lu, Ind. Eng. Chem. Res. 54 (2015) 5460-5467;
[5] Z. Sui, Q. Meng, X. Zhang, R. Ma, B. Cao, J. Mater. Chem. 22 (2012) 8767;
[6] D. Loche, L. Malfatti, D. Carboni, V. Alzari, A. Mariani, M.F. Casula, RSC Advances 6 (2016) 66516-66523
5:15 PM - NM3.9.03
Mechanically-Durable Aerogels—A Path toward Transformed Oil Remediation Strategies
Desiree Plata 1 , Osman Karatum 1 , Stephen Steiner 2
1 , Yale University, New Haven, Connecticut, United States, 2 , Aerogel Technologies LLC, Boston, Massachusetts, United States
Show AbstractFew fields of engineering have been untouched by the rapid pace of materials science discovery over the past forty years, with some notable exceptions. In particular, oil spill remediation technologies are very much the same today (e.g., the Macondo well blowout of April 2010) as they were in the late 1970s (e.g., Ixtoc I well blowout of June 1979). However, mechanically-robust, flexible, hydrophobic aerogel blankets show promise as oil remediation and recovery materials. Using two types of aerogels, Cabot™ Thermal Wrap® (TW) and Aspen Aerogels Spaceloft® (SL), we demonstrated that crude oils uptake 8.0 ± 0.1 and 6.5 ± 0.3 g g-1 (Iraq and Bryan Mound Sweet Oils, respectively) for SL and 14.0 ± 0.1 and 12.2 ± 0.1 g g-1 for TW, respectively, nearly twice as high as similar polyurethane and polypropylene-based devices. Mechanical extraction routes under a modest compression force (38 N) yielded 42.0 ± 0.4 % over 10 reuse cycles for SL. Life cycle assessments indicated that SL manufacture offered materials and energy benefits relative to competing oil sorbent technologies (i.e., polyurethane foams; PUF), even under single-use and landfill disposal scenarios. These benefits improve under the reuse and waste-to-energy disposal scenarios made possible by SL’s mechanical durability and ability to discriminate against water uptake: SL can be made at an energetic costs of 0.6 x 103 MJ/m3 spilled oil but generate a net of 7.9 x 103 MJ/m3 oil under waste-to-energy (32 kg SL), whereas PUF costs 3.8 x 103 MJ/m3 to produce (152 kg PUF). The initial cost of these materials for a 1000-ton spill, when purchased in bulk, would be $1.48M versus $0.48M for PUF and SL, respectively, where the latter presents and opportunity for recovered revenue in the form of useful oil products. Taken as a whole, blanket aerogels will ultimately enable improved oil uptake, potential reuse of collected oil, reduced material and energy burdens compared to competitive sorbents, and reduced occupational exposure to oiled sorbents, and these can be deployed via scaled fabrication technologies today.
5:30 PM - NM3.9.04
Sucrose-Derived Carbon Sponge with Superporous, Superhydrophobic, Oleophilic and Ferromagnetic Properties for Environmental Cleaning
Daisy Patino 1 , Hamed Hosseini Bay 1 2 , Zafer Mutlu 1 , Mihri Ozkan 1 , Cengiz Ozkan 1
1 , University of California, Riverside, Riverside, California, United States, 2 , Tufts University, Medford, Massachusetts, United States
Show AbstractThe demand for environmentally sustainable engineered systems continues to rise in effort to support human well-being and to preserve natural habitats. One principal focus within this global effort is to develop novel means for water decontamination and oil/water separation. Herein, we present a sucrose-derived, superporous, superhydrophilic, oleophilic carbon sponge that can successfully separate various oils, organic solvents, and toxic and corrosive contaminants from water. Uniquely, our eco-friendly Carbon Sponge is synthesized via a facile sol-gel process that is inexpensive and scalable. Additionally, our fabricated Sponge has the advantage of being utilized in various physical forms. For example, pulverized Sponge has shown to absorb water contaminants up to 50 times its weight, as compared to 20 times its weight when used in large solid pieces. Our Sponge is ideal for multi-use sorption processes, as it can be collected with a magnet, due to its ferromagnetic properties, and purged of the contaminants through various methods. We hope that such a unique, eco-friendly, and cost-effective material can be embraced and implemented widely in the initiative for clean water supply.
5:45 PM - NM3.9.05
Ultralight and Mechanically Robust Cellulose Ester Aerogels for Environmental Remediation
Anurodh Tripathi 1 , Saad Khan 1 , Orlando Rojas 1 2
1 , North Carolina State University, Raleigh, North Carolina, United States, 2 Department of Forest Product Technology, School of Chemical Technology, Aalto University, Helsinki Finland
Show AbstractCellulosic aerogels are biodegradable but they generally suffer from weak mechanical integrity and disintegrate under water due to presence of hydrophilic hydroxyl groups. This limits their performance in separating oil from rough oceanic environment. Herein, we report the synthesis of highly porous (99.7 %), ultra-light (4.3 mg/ml) yet mechanically robust cellulose acetate aerogels with tailored hydrophobicity. In its native, unmodified state, the aerogels are hydrophilic and oleophilic that display unprecedented water and oil uptake of 92 and 112 g/g respectively, while affording wet strength. The 4 w/v% cellulose acetate (4%) aerogels with a density of 24.3 mg/ml, achieve maximum compression strain of 92 % without failure and reach a compressive stress of 350 kPa, which is 100-fold higher than that reported for cellulosic aerogels. Further adjustment of the 4% aerogels towards hydrophobicity and oleophilicity via chemical vapor deposition with an organo-silane species reveal them to exhibit high oil retention (20-30 g/g aerogel) with minimal water uptake while maintaining mechanical integrity for fast oil cleanup from aqueous media under marine conditions. The modified aerogels are reusable and durable as they retain their hydrophobicity for months under ambient conditions. The Zisman and Fowkes theoretical frameworks are used to identify the selectiveness of the aerogel and establish a criterion for separation of various non-polar fluids from water media thereby providing a general platform for predicting the sorption.
Symposium Organizers
Stephen Steiner, MIT
Stephanie Brock, Wayne State University
Alexander Eychmueller, TU Dresden
Nicholas Leventis, Missouri University of Science and Technology
Symposium Support
Aerogel Technologies, LLC
Aspen Aerogels, Inc.
BASF Polyurethanes GmbH
Blueshift
JEOL USA, Inc.
NASA–Glenn Research Center
NM3.10: Carbon Aerogels
Session Chairs
Hai Duong
Alexander Eychmueller
Thursday AM, April 20, 2017
PCC West, 100 Level, Room 105 BC
9:00 AM - *NM3.10.01
The Evolution of Carbon Aerogels—Allotropes, Composites and Graphene-Inspired
Marcus Worsley 1
1 , Lawrence Livermore National Lab, Livermore, California, United States
Show AbstractCarbon aerogels are a unique class of high-surface-area materials derived by sol–gel chemistry. Their high mass-specific surface area and electrical conductivity, environmental compatibility and chemical inertness make them very promising materials for many applications, such as energy storage, catalysis, sorbents and desalination. Since the first carbon aerogels were made via pyrolysis of resorcinol-formaldehyde-based organic aerogels, in the late 80’s, the field has really grown. Recently, in addition to RF-derived amorphous carbon aerogels, several other carbon allotropes have been realized in aerogel form: carbon nanotubes, graphene, and diamond. Furthermore, the popularity of graphene aerogels has inspired research into aerogels made of a host of graphene analogue materials (e.g. boron nitride, transition metal dichalcogenides, etc.), with potential for an even wider array of applications. Finally, the development of 3D-printed aerogels provides the potential of carbon aerogels to have an even broader impact on energy-related technologies. Here, we will present recent work covering the novel synthesis of RF-derived, CNT, graphene, diamond, composite, and graphene analogue aerogels, as well as their performance in a variety of applications.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
9:30 AM - NM3.10.02
Carbon Aerogels and Carbon Aerogel Composites
Wendell Rhine 1 , Redouane Begag 1 , Nick Zafiropoulos 1 , Wending Dong 1 , David Mihalcik 1 , Irene Melnikova 1 , Shannon White 1
1 , Aspen Aerogels, Inc., Northborough, Massachusetts, United States
Show AbstractMany industrial processes are carried out at temperatures higher than 1200 °C, but there are not many highly efficient insulation materials available that are thermally stable at these temperatures. Developing highly efficient aerogel insulation materials that are stable at these high temperatures presents some unique challenges. Aspen Aerogels is developing carbon aerogels and carbon aerogel/carbon fiber-reinforced insulation materials that are thermally stable and could be used as insulation materials for high temperature processes. We will discuss the preparation of these materials and their mechanical and thermal properties.
9:45 AM - NM3.10.03
Polymeric Aerogels as a Point of Departure for Fundamental Mechanistic Studies—The Case of Polybenzoxazine and Other Phenolic Type Aerogels
Nicholas Leventis 1 , Suraj Donthula 1 , Shruti Mahadik-Khanolkar 1 , Hojat Majedi-Far 1 , Adnan Malik Saeed 1 , Chariklia Sotiriou-Leventis 1
1 , Missouri University of Science & Technology, Rolla, Missouri, United States
Show AbstractPolybenzoxazines (PBOs) are a class of phenolic resins, pretty much like those from resorcinol-formaldehyde. They are pursued mainly as cost-effective alternatives to polyamides for high temperature applications. PBO aerogels are synthesized via heat-induced condensation polymerization (typically at 130 oC) of bisphenol A, aniline and formaldehyde in suitable solvents. Gelation takes a few days. Curiously, the carbonization yield of those aerogels is more than double the one reported for the bulk material. By implementing a new time-efficient (a few hours) room-temperature HCl-catalyzed synthesis of PBO aerogels, we have been able to deconvolute gelation from curing and we found that in addition to polymerization, high temperatures cause oxidation of the -CH2- bridges along the polymeric backbone, followed by fusion of the phenol and aniline rings. That oxidative aromatization process renders the polymeric backbone rigid and becomes responsible for high carbonization yields (up to 61% v/v). Carbon aerogels from aromatized PBO aerogels are microscopically similar to their respective parent aerogels, however, they have greatly enhanced surface areas, up to 520 m2 g-1 (from ≤70 m2 g-1 in the parent aerogel) with up to 83% of that new surface area attributed to newly created micropores. Applications specific to those findings include synthesis of iron oxide/polybenzoxazine interpenetrating networks as precursors of iron(0) aerogels, and use of microporous carbons for CO2 sequestration. Using the PBO chemistry as a point of departure, we have explored whether oxidative ring fusion aromatization can take place in other phenolic resins (e.g., phenol-formaldehyde, resorcinol-formaldehyde and phloroglucinol-formaldehyde), and we found that this chemistry is general. In the case of the latter three systems the aromatization product is the pyrylium cation. Although carbonization yields were not altered (this is because further pyrolysis proceeds through common intermediates), it was found that early rigidization via aromatization leads to higher surface area carbon aerogels.
10:00 AM - NM3.10.04
Tailoring of Pores in Carbon Aerogels Using 3D Printed Structures
Swetha Chandrasekaran 1 , Patrick Campbell 1 , James Oakdale 1 , Julie Jackson 1 , Marcus Worsley 1 , Theodore Baumann 1 , Eric Duoss 1 , Christopher Spadaccini 1 , Juergen Biener 1
1 , Lawrence Livermore National Laboratory, Livermore, California, United States
Show AbstractCarbon aerogels (CAs) are porous low-density solids that combine many unique properties such as ultra-high surface area, electrical conductivity, and good mechanical stability that make them the material of choice for a variety of applications. However, traditional CA synthesis methods typically result in isotropic materials with uniform density which limits their potential in applications that would benefit from anisotropic properties such as uniaxial density gradients or directional mass transport properties. On the other hand, additive manufacturing (AM) techniques such as projection micro stereo lithography (PuSL) and two-photon-polymerization (2PP) direct-laser-writing (DLW) provide deterministic control over the 3D architecture over multiple length scales, from 100s of nanometers to 10s-100s of microns, with overall part dimensions up to centimeters. These techniques are based on photo-polymerization of liquid resins. Here, we report on a new templating strategy what allows us to fabricate CAs with engineered anisotropic density profiles and mass transport properties by using 3D AM parts produced via PuSL and 2PP-DLW techniques as sacrificial templates for CA synthesis. The parts are infilled with resorcinol-formaldehyde (RF) organic gels and subsequently carbonized at 1050°C, to yield the templated CA while simultaneously removing the sacrificial AM polymer template. The final product is the negative template of the 3D printed structure in a porous carbon aerogel matrix.
Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 15-ERD-019. This work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.
10:15 AM - NM3.10.05
Mesoscopic Simulations of Structural and Mechanical Properties of Carbon Nanotube Aerogels
Alexey Volkov 1 , Md Abu Horaira Banna 1
1 , University of Alabama, Tuscaloosa, Alabama, United States
Show AbstractStructural and mechanical properties of aerogels composed of single-walled carbon nanotubes (CNTs) are studied in mesoscopic simulations. In the mesoscopic model of CNT materials, every nanotube is represented by hundreds of cylindrical segments. The mesoscopic model accounts for stretching, bending and buckling of individual CNTs, their van der Waals interaction with each other, and covalent cross-links between nanotubes. The van der Waals interaction is described based on a ‘tubular’ potential method that ensures the absence of artificial friction between curved CNTs. The model of covalent bonds between CNTs is parameterized based on results of atomistic simulations of cross-links induced by irradiation of CNT bundles with energetic ion beams. The structures of interconnected networks of CNT bundles are obtained in dynamic mesoscopic simulations in the range of the CNT length from 200 nm to 1000 nm and material density from 0.001 g/cm3 to 0.1 g/cm3. The simulations start from random distribution of straight disperse CNTs with various degrees of inter-tube alignment and result in the formation of entangled networks of CNT bundles. The cross-links between CNTs are distributed after formation of the continuous networks in simulated samples. A few qualitatively different structures of CNT networks are found depending on the length of CNTs, material density, and parameters that define the degree of initial alignment of CNTs. The minimum density of the CNT aerogel, which ensures formation of a stable network of nanotubes, is determined as a function of the CNT length. Statistical distributions of pores and sizes of CNT bundles in the simulated samples are established. Elastic and inelastic mechanical properties of aerogels are studied in dynamic simulations of stretching and compression. The simulations reveal a strong effect of thickness of CNT bundles and density of cross-links on Young’s modulus and strength of the CNT aerogels. This work is supported by the NSF CAREER award CMMI-1554589 and NASA Early Stage Innovations program (project NNX16AD99G).
NM3.11: Assemblies of Zero- and One-Dimensional Biopolymers and Nanocarbons
Session Chairs
Stephanie Brock
Marcus Worsley
Thursday PM, April 20, 2017
PCC West, 100 Level, Room 105 BC
11:30 AM - *NM3.11.01
Mass Production and Applications of Carbon Nanotube Aerogels and Cellulose Aerogels from Environmental Waste
Hai Duong 1
1 , National University of Singapore, Singapore Singapore
Show AbstractA direct and scalable floating catalyst method to fabricate the self-supporting carbon nanotube (CNT) aerogels at higher deposition rates is developed successfully. The whole fabrication process takes only about 1-2 hours and can produce meter-long CNT aerogels continuously without using freeze drying and supercritical drying processes. The undeniable advantages of the established process also include its precise control of the amount of impurities and morphology of the CNT aerogel. With different collecting techniques and after the post treatments, we can produce the super strong km-long CNT fibers and also meter-scale aligned CNT thin films with their excellent multi-properties. The density of the aerogels ranges from 0.55 to 32 mg/cm3 with high porosity (>98%) and surface area of up to 170 m2/g. The CNT aerogels are not brittle, easy on handling and even the lightest ones can withstand a weight of ~150 times higher than their own (~15000 times higher than its density) without collapsing. The thermal and electrical conductivities are also quantified and better than those reported for the CNT aerogel coated with graphene, pure graphene- or graphene/CNT aerogels, and other CNT aerogels synthesized using the freeze-drying and critical point-drying methods.
Also cellulose aerogels from environmental waste for several applications such as oil spill cleaning and thermal insulation of buildings are developed successfully. A more facile, cost effective, much less time-consuming fabrication method is innovated. The continuous and large-scale process takes only three days and uses much less non-toxic chemicals such as recycled cellulose fibers from paper- or fabric- waste, water and Kymene as a cross-linker. The MTMS-coated aerogels can absorb oil excluding water 4 times larger than that of the best commercial sorbents. The cellulose aerogels can be squeezed to recover over 99% of absorbed crude oil. Thermal conductivities of 1.0 - 4.0 wt.% cellulose aerogels are 0.034 - 0.037 W/m.K. The water-repellent aerogel structures are stable over 6 months in tropical climate. The compressed cellulose aerogel in the tablet form can be effective to be used to haemorrhage control. This technology gives a promising solution for the global environmental pollution and energy problems.
12:00 PM - NM3.11.02
Multiscale Order in Self-Aligned Carbon Nanotube Aerogels
Eric Meshot 2 , Darwin Zwissler 2 , Ngoc Bui 2 , Chaitai Chen 2 , Steven Buchsbaum 2 , Tevye Kuykendall 3 , Cheng Wang 1 , Alexander Hexemer 1 , KuangJen Wu 2 , Francesco Fornasiero 2
2 Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States, 3 The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 1 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California, United States
Show AbstractFundamental understanding of structure-property relationships in complex, nanocarbon aerogels is crucial for the discovery and development of new functionalities. We recently demonstrated promising applications of vertically aligned carbon nanotube (CNT) “forests” as model, porous nanocarbon aerogels – e.g., for shock absorption1 and bio-protective garments2. However, detailed mapping of the relationships between functionality and multiscale structure has remained lacking because quantifying their structure across multiple length scales is challenging.
To address this knowledge gap, we used nondestructive X-ray scattering to quantitatively map the multiscale structure of self-aligned CNT aerogels grown by catalytic chemical vapor deposition (CVD). We leveraged a set of complementary hard/soft X-ray beamlines at the Advanced Light Source in order to quantify and correlate the structural order in CNT forests across four orders of magnitude in length scale, from 1.4 Å to 1 µm. Probed structural features include the sp2-hybridized honeycomb lattice (atomic), the graphitic wall and CNT alignment (nano), as well as the greater CNT ensemble (meso) and large corrugations (micro). We found that the orientational order within a single forest exhibited a cascading decrease as we probed finer structural feature sizes. Further, by synthetically tuning the CNT forest structure over a wide range of characteristics (e.g., 1-11 walls, 1.5-15 nm diameter, 10-47 mg cm-3 mass density, 1010-1012 cm-2 packing density), we established qualitative relationships. To that end, we revealed that the multiscale orientational order is directly correlated with packing density, yet we found it is inversely proportional to CNT diameter, number of walls, and atomic defect density.
Lastly, we combined SEM imaging, soft X-ray scattering, and a phenomenological model to fully characterize microscale corrugations along the CNT growth direction as well as their dependence on other structural features. Despite the prevalence of this type of morphology reported in literature and its potential importance toward understanding how these CNT materials are formed, until now there had been a lack of robust, quantitative characterization of these ripples. By providing detailed structural information at multiple length scales, our methodology opens opportunities to advance design and synthesis of novel nanocarbon aerogel materials as well as other hierarchically organized structures.
This work is supported by the Defense Threat Reduction Agency (DTRA) D[MS]2 project under Contract No. BA12PHM123 and was performed under the auspices of U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
1. R. Thevamaran, E.R. Meshot, C. Daraio. Carbon 84, 390, 2015.
2. N. Bui, E.R. Meshot, S. Kim, J. Peña, P.W. Gibson, K.J. Wu, F. Fornasiero. Advanced Materials 2016, 28, 5871-5877.
12:15 PM - NM3.11.03
Direct Synthesis and Properties of Low-Density Nanofibrous Carbon Structures
Roger Welsh 1 , David Edwards 1 , Laura Guevara 1 , Mark Atwater 1
1 , Millersville University, Millersville, Pennsylvania, United States
Show AbstractA recently developed method can create bulk, three-dimensionally tailored structures by confining the growth of carbon nanofibers. This technique has been demonstrated to produce nonwoven materials with controllable density, and it results in mechanically robust structures of less than 3% theoretical density for amorphous carbon. This material has been found to be stable under cyclic mechanical loading at strains exceeding 0.40, and the elasticity can be controlled through processing conditions. The structures are readily infiltrated with gases and liquids, and the as-grown fibers have a surface area exceeding 200 g/m2 and may be increased through activation of the carbon. This method has primary benefits of being low-cost, scalable and able to create stable bulk structures with nearly any geometry, thereby easing application integration. The methods, properties and applications will be compared and contrasted to current aerogel materials.
12:30 PM - NM3.11.04
Solvent-Vapor Infusion Driven Self-Assembly of Fullerene Nanostructures
Tony Jefferson Gnanaprakasa 1 , Selene Sandoval 1 , Kurumi Austin 1 , Palash Gangopadhyay 2 , Srini Raghavan 1 3 , Krishna Muralidharan 1
1 Materials Science and Engineering, The University of Arizona, Tucson, Arizona, United States, 2 College of Optical Sciences, The University of Arizona, Tucson, Arizona, United States, 3 Chemical and Environmental Engineering, The University of Arizona, Tucson, Arizona, United States
Show AbstractThe ability to enable self-assembly of fullerenes in to complex structures through nanoarchitectonics, and utilizing these macro-scale self-assemblies for technological applications is demonstrated in this work. Using a solvent-vapor infusion process involving combinations of solvents and non-solvents, self-assembled fullerene structures such as rods, hexagonal discs, as well as complex shapes such as bristles, flowers, and adobe brick wall-like macrostructures (length: 5 µm to 3000 µm; width: 30 nm to 5 µm) have been controllably obtained. Further, these structures can be self-assembled on to a number of substrates (hydrophilic and hydrophobic), by suitably modifying the solvent-substrate wetting, substrate surface roughness, solvent polarity, temperature, and solubility of fullerene molecules. An exceptional feature of the method is that this self-assembly process through materials nanoarchitectonics can be scaled-up, with high uniformity, and complex hierarchical clustering leading to self-similar structures across scales with tunable porosity. The difference in polarity and surface tension of the C60/solvent versus the infusing non-solvent vapors play a critical role in the segregation, crystallization, and self-assembly of C60 to form nanostructures of various sizes and shapes. Our method opens up novel avenues to engineer, and self-assemble fullerene nanostructures for multifunctional agile materials systems. Further, we also discuss and demonstrate the role of such self-assemblies in materials for hybrid electrochemical energy storage applications.
12:45 PM - NM3.11.05
Cellulose Aerogel and Its Graphitized Aerogel for High-Performance Lithium-Sulfur Battery
Nazifah Islam 1 , Guofeng Ren 1 , Zhaoyang Fan 1
1 Electrical & Computer Engineering, Texas Tech University, Lubbock, Texas, United States
Show AbstractOf the several challenges for developing lithium-sulfur battery (LSB), the shuttle effect of the soluble polysulfide intermediates is the most serious. The soluble polysulfides shuttle back and forth between the sulfur cathode and the lithium anode, resulting self-discharging, capacity loss, Li anode etching, and many other severe consequences. Carbon conductive aerogel, which can hold a large amount of catholyte for sulfur cathode, and cellulose aerogel, which can form gel electrolyte to replace the conventional separator and liquid electrolyte, were studied to solve the above problem.
In this study, bacterial cellulose aerogel and its graphitized aerogel were investigated for high-performance LSB development. The bacterial cellulose aerogel and its graphitized form, consisting of interweaved nanofibers with large surface area and micro- and meso-porous structure, have a very low mass density but can strongly hold large amount of electrolyte and catholyte. Therefore, the cathode can simultaneously achieve both high sulfur content and high sulfur loading. The gel electrolyte further retards the diffusion of polysulfides to the anode. Due to the synergetic effects of the aerogel based cathode structure and the gelled electrolyte, the shuttle effects of polysulfides are significantly impressed. LSB cells with outstanding performance was demonstrated. We will report the detail studies on the bacterial cellulose and graphitized aerogel structures, their electrochemical properties as electrolyte gel or sulfur cathode, and particularly the outstanding cell performance when they are applied for LSB cell fabrication.
NM3.12: Industrialization and Commercialization
Session Chairs
Nicholas Leventis
Wibke Loelsberg
Thursday PM, April 20, 2017
PCC West, 100 Level, Room 105 BC
2:30 PM - *NM3.12.01
nexAERO—A Disruptive Aerogel Materials Company—Technology, Key Markets and Vision
Matthias Koebel 1
1 , Empa - Swiss Federal Laboratories for Materials Science and Technology, Duebendorf Switzerland
Show AbstractWith a share of 40% of the total energy consumption, a reduction of the energy consumption of buildings for heating and cooling is regarded as the most promising way to curb climate change. This can be done most economically by putting in place proper thermal insulation. Such measures are effective for both new and already existing buildings, although the savings potential for the existing building stock, is considerably larger. However, not only buildings but also industrial manufacturing sites, district heating pipe networks, automotive interiors, engine bays and battery packs can greatly profit from compact high-performance insulation solutions. Yet, today’s insulation markets are in dire need of a change. Many conventional products such as glass wool or polystyrene foam are bulky, not sustainable and have reached the peak of their product lifecycle. Innovation and technological progress in the industry is marginal or nonexistent. At the same time global energy policy is imposing stricter insulation standards which would call for thicker but impractical insulation layers.
nexAERO is a young, dynamic and highly innovative aerogel technology startup company in the high performance materials sector, specializing in the scale-up of aerogel materials. Its primary mission is to develop, manufacture and distribute disruptive silica aerogel raw materials with identical performance of today’s competing products at >40% lower cost. Downstream, the company is developing novel aerogel-based compounding solutions which, starting from a single platform technology, enables manufacturing of a large variet of products and solutions which can be custom-tailored to the end user’s needs and specifications. The company’s value architecture is based on i) direct sales of aerogel granulate and ii) key account management for larger distributors and partners including licensing and operation of aerogel compounding facilities.
nexAERO’s current technology relies on making silica aerogel which is something that other competitors produce already but in a much more efficient way. By itself, silica aerogels are a tremendous market opportunity with a current market volume of approximately US$ 250M per annum (2015). Our unique production technology allows for faster, and simpler manufacturing of aerogels with significantly lower CAPEX and OPEX, solvent use and CO2e. On the commercialization side, we collaborate with well-established industry leaders in B&C and industrial insulation sectors. The presentation gives an overview of the copany’s setup, vision, technology and product portfolio. Given its strong technology leadership in the form of its key staff, nexAERO is primed to continue to innovate and multiply technological solutions and success far beyond the scope of its initial silica aerogel technology roadmap.
3:00 PM - NM3.12.02
Commercialization of Mechanically Strong, Multifunctional Monolithic Aerogels—Airloy® Ultramaterials
Stephen Steiner 1 , Justin Griffin 1 , Ryan Nelson 1 , John Schneider 1 , Mark Schneider 1
1 , Aerogel Technologies, LLC, Boston, Massachusetts, United States
Show AbstractAerogels are a diverse class of nanoporous materials that simultaneously exhibit a diverse array of extreme materials properties in the same material envelope. To date the commercial focus of aerogels has primarily been on their thermal superinsulating properties, however other materials properties of aerogels such as their high mass-normalized mechanical properties, high internal surface area, and energy damping properties are also potentially interesting for commercial applications. Aerogels have traditionally been too brittle for use in many applications and as a result forms of aerogels that circumvent their fragility such as fiber-reinforced composites and aerogel particles have been the most successful commercial form factors. Over the past fifteen years, however, a number of new mechanically strong aerogels have been produced that enable applications such as their use as lightweight plastics replacements. We have commercialized a number of monolithic mechanically strong aerogels for use in aviation interiors, automotive engineering, engineering materials, construction, and consumer electronics plastics under the trade name Airloy. Airloy aerogels exhibit the strength and durability expected of engineering materials yet are 3-15x lighter than plastics or composites. This said, there are many good lightweight engineering materials available such as foams and natural materials, and competing against them requires analysis of both the value propositions of strong aerogels and markets where aerogels could be beneficial. Our efforts at commercialization of monolithic mechanically strong aerogels will be presented. The science of monolithic mechanically strong aerogels in terms of multifunctional materials and materials parameter space will be discussed. Aerogel formulations desirable for commercialization, product development needs, and scale up considerations of monolithic aerogels will be analyzed. Marketing of strong aerogel materials and how we have positioned them will be discussed. Future and current applications of monolithic mechanically strong aerogels will also be presented.
3:15 PM - NM3.12.03
Lean Aerogel Manufacturing—Overview towards Efficient Industrial Aerogel Productions
Francisco Ruiz 1 , Kanda Philippe 1 , Digambar Nadargi 1
1 , Keey Aerogel, Schlierbach France
Show AbstractThe production of aerogel-based materials has suffered a massive evolution in the past 10 years, as an attractive and alternative solution to many applications. And hence, the commercial success of some aerogel references is an undoubted reality today. However, the technological development of the production still remains on the validation and optimization stages at Technology Readiness Levels (TRL) significantly low compared to the maturity of the market. Therefore, the steps towards the development of “continuous” production lines to host shorter synthesis and/or drying cycles leads the future aerogel innovation and hence its market.
LEAN AEROGEL MANUFACTURING (LAM) is a term to label the conceptualization of the efficiency in aerogel production from the raw material procurement, manufacturing process selection to the final aerogel product disposal, with the awareness in costs, health, safety and environment. This notion is crucial in all stages of the aerogel development in order to better enlighten the manufacturing limits with the most adequate methods and technology in each single cases.
The present study attempts to be a tour through the production processes of different types of aerogels using the most innovative methods and including the critical points and limits to be addressed based on the LEAN AEROGEL MANUFACTURING concept.
3:30 PM - NM3.12.04
Development of Roll to Roll Polyimide Aerogels
Garrett Poe 1 , David Irvin 1 , Alan Sakaguchi 1 , David Anderson 1 , Robert Pescatore 1 , Tim Liu 1
1 , Blueshift International Materials, Inc., San Marcos, Texas, United States
Show AbstractSince their discovery in 1931, aerogels have developed from a laboratory oddity to commercially available products. These remarkable materials can be made from silicon oxide, metal oxides, carbons, and more recently polymers. In additional to agar and cellulous, polymers such as resorcinol-formaldehyde and polyimides have been successfully used to produce aerogels. Blueshift International Materials, Inc., produces a 100 percent-polymer aerogel based on polyimides and other polymers. In addition, to making traditional solid castings, we have demonstrated the production of thin film aerogels in a roll to roll format. One example of this is a 50 micron thick by 60 cm wide roll of 100 percent-polyimide aerogel. Unlike traditional polymer films, these films are 85 percent air and comprised of nano-sized pores. These nanopores provide excellent thermal and acoustic insulation. As a thin film, these materials are flexible and can conform to curved and cylindrical shapes. Applications for these new flexible 50 micron films include composite structures that require a very thin and lightweight insulation or dielectric layer, such as electronics for aircraft, and satellites.
3:45 PM - NM3.12.05
Recent Developments and Applications of Engineered Aerogels at Taasi
Yosry Attia 1
1 The Attia Applied Sciences Inc., Taasi Corporation, Delaware, Ohio, United States
Show AbstractTAASI Corporation has been engaged in the business of aerogel products and aerogel technologies development since 1992, for a wide variety of industrial and other applications, spanning across 50 industrial sectors, and over 550 companies.
Recent developments at TAASI include: aerogel fibers and fiber webs for aerogel textiles and other applications; capsulated polyethylene aerogel for absorption of excess lipids and bile in situ with significant reduction of body cholesterol; improved capture of VOC from tobacco smoke; Nylon aerogel flexible sheets; preparation of water-resistant and oil-resistant aerogel materials; enhanced cancer drug delivery with PEG aerogel.
The presentation will briefly discuss each of these developments as time allows.
NM3.13: Advances in Aerogel Insulation
Session Chairs
Matthias Koebel
Stephen Steiner
Thursday PM, April 20, 2017
PCC West, 100 Level, Room 105 BC
4:30 PM - *NM3.13.01
SLENTITE®—The Robust PU Aerogel Panel
Wibke Loelsberg 1 , Marc Fricke 1 , Dirk Weinrich 1
1 , BASF, Lemförde Germany
Show AbstractWith the continuous rise of energy prices - a trend without foreseeable end - the pressure for higher energy-efficiency across many markets is increasing. In construction and appliance industries, this has created a growing demand for new thermal insulation solutions superior to established materials such as EPS, PU foam or mineral wool. Furthermore, it has become apparent that excellent insulation performance alone is no longer sufficient - smart materials with tunable properties such as humidity control for better room climates are required to answer the challenges of the future. BASF Performance Materials is meeting this trend with a new organic aerogel board. This nano-porous, high-performance thermal insulation material exhibits properties surpassing simple insulation.
5:00 PM - NM3.13.02
Application of Aerogel Blanket Insulation in Exterior Wall Constructions
Phalguni Mukhopadhyaya 1 , Lawrence Carbary 2 , Stanley Yee 2 , David Appelfeld 2 , Jack Guan 2
1 , University of Victoria, Victoria, British Columbia, Canada, 2 , Dow Corning, Midland, Michigan, United States
Show AbstractDemands for energy efficient buildings around the world are creating new opportunities for advanced thermal insulation materials and technologies. Aerogel insulation in blanket form is an advanced thermal insulation having thermal resistance at least 2 times higher than high-performance closed-cell foam insulation. Aerogel in blanket form can be rolled and cut to any reasonable size or shape, like traditional glass or mineral fiber insulations. The blanket can also be used in multiple layers. Considering all these advantages and global need for energy efficient building, the mass application of aerogel blanket insulation in exterior wall constructions appears to be an attractive proposition. However, construction industry professionals need design details, long-term performance credentials and construction guidelines to accelerate the integration of aerogel blanket insulation in exterior building envelope constructions. This paper presents observations from laboartory measurements, numerical simulations and field constructions to demonstrate possible opportunities and challenges concerning the application of aerogel blanket insulations in exterior wall constructions.
5:15 PM - NM3.13.03
Stabilization of Alumina and Aluminosilicate Aerogels for High Temperature Applications
Frances Hurwitz 1 , Haiquan Guo 2 , Richard Rogers 1
1 , NASA-GRC, Cleveland, Ohio, United States, 2 , Ohio Aerospace Institute, Cleveland, Ohio, United States
Show AbstractA variety of thermal protection applications require lightweight insulation capable of withstanding temperatures well above 900C. Aerogels offer extremely low-density thermal insulation due to their porous structure, which inhibits both gas convection and solid conduction. Silica aerogel systems are limited to use temperatures of 600-700C, above which they sinter. Alumina aerogels maintain a porous structure to higher temperatures than silica, before transforming to α-alumina and densifying. We have explored several methods for doping alumina aerogels to inhibit phase transformation to α-alumina with accompanying densification, including the use of Si, Y and Na as dopants. Phase transformations and their influence on chemical bonding and aerogel pore structure as a function of both temperature and time were characterized, utilizing a combination of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and nitrogen desorption analysis. Aerogel compositions stable to 1200C have been demonstrated.
5:30 PM - NM3.13.04
Fibre Reinforced Silica Aerogel Blankets by Ambient Pressure Drying for Thermal Protection
A. Venkateswara Rao 1 , S. Chakraborty 2 , V. K. Kothari 2 , G.M. Pajonk 3 , A. A. Pisal 1
1 , Shivaji University, Kolhapur India, 2 Department of Textile Technology, Indian Institute of Technology, New Delhi, New Delhi, New Delhi, India, 3 , Laboratorie d' Application de la chimiea Environment, Universite Claude Bernard-Lyon I, Villeurbaunce Cedex, France, Villeurbaunce Cedex France
Show AbstractIn the present paper, the experimental results on the development of fibre reinforced hydrophobic silica aerogel blankets by ambient pressure drying method, are reported. The aerogel blankets have been produced using a Nomex meta-aramid fibre matrix and silica sol based on tetraethoxysilane (TEOS) precursor. The silica alcosols were produced by a two-step acid-base sol – gel processing of methanol (MeOH) diluted TEOS in the presence of oxalic acid (COOH)2 and ammonium fluoride (NH4F) catalysts. The molar ratio of TEOS:MeOH:(COOH)2:NH4F was kept constant at 1:38: 3.75 x 10-5 : 0.023, respectively. Silica alcogel was allowed to form inside the porous meta-aramid fibrous batting. The methanol solvent in composite alcogel was exchanged with hexane at 50oC in a shaker at 120 rpm for 3 hours. The wet composite gel was silylated using trimethylchlorosilane (TMCS) of concentrations ranging from 1 to 20% by volume ratio in hexane. The fibre reinforced silica aerogel blanket was obtained subsequently by ambient pressure drying method. The aerogel blanket samples have been characterized by density, wettability (contact angle) porosity and Scanning Electron Microscopy. The radiant heat resistance of the aerogel blankets has been examined and compared with the non-aerogel blankets. It has been observed that compared to the ordinary non-aerogel blankets, the aerogel blankets showed around 60% increase in the estimated burn injury time and thus ensure a much better protection from heat and fire hazards. The effect of varying the TMCS concentrations on the estimated protection time has been examined. The results have been discussed by taking into account of porosity and pore sizes and the extent of silylation of the aerogel blankets.
5:45 PM - NM3.13.05
Effect of Aging on Silica Aerogel Properties and the Structure of Glass Wool-Aerogel Composites by X-Ray Tomography
Subramaniam Iswar 1 2 , Wim Malfait 1 , Michele Griffa 1 , Matthias Koebel 1 , Marco Lattuada 2
1 , Swiss Federal Laboratories for Materials Science and Technology, Empa, Duebendorf Switzerland, 2 , Adolphe Merkle Institute, University of Fribourg, Fribourg Switzerland
Show AbstractSilica aerogel’s unique physical and chemical properties make them fascinating materials for a wide variety of applications. In addition to silylation, aging is an equally important and essential condition for the synthesis of low density silica aerogels by ambient pressure drying (APD). Here, we systematically study the effect of aging on the physico-chemical properties of silica aerogel with emphasis on ambient dried materials. Silica aerogels were aged for different times and temperatures in the gelation liquid (without solvent exchange), hydrophobized in hexamethyldisiloxane and subsequently dried either at ambient pressure or by supercritical CO2. With increasing aging time and temperature, the linear shrinkage and bulk density decrease and the pore size and pore volume increase for the ambient dried gels, but remain nearly constant for supercritically dried gels. Aging strengthens the inter-particle necks of the silica gel pearl-necklace structure through dissolution-reprecipitation processes akin to Ostwald ripening that are driven by the energy minimization through the reduction of total surface area. Dynamic oscillatory rheological measurements also demonstrated that aging reinforces the silica alcogels, particularly at high strain rates. This study was further expanded to see the influence of aging and drying processes on the thermal conductivity of fiber reinforced silica aerogel composites. The trends in thermal conductivity of glass wool-aerogel composites prepared at different aging times were linked to the structure of the samples as determined by X-ray tomography which showed that the total macro-porosity of APD glass wool-aerogel composites decreases with increasing aging time. The findings of this study correlate the 3D quantitative characterization of drying shrinkage cracking in fiber reinforced aerogel composites by X-ray tomography with the thermal conductivity. Our results highlight the importance of aging for the synthesis of low density silica aerogels or low thermal conductivity glass wool-aerogel composites by ambient pressure drying.
NM3.14: Poster Session II: Aerogels and Aerogel Inspired Materials—Carbon, Assemblies of 0D and 1D Nanostructures, Frontier Aerogels, Environmental Remediation, Processing and Light and Sound
Session Chairs
Stephanie Brock
Nicholas Leventis
Friday AM, April 21, 2017
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - NM3.14.01
Tuning Aerogels for High Potential Thermoelectric Materials
Kristian Schneider 1 , Alexander Eychmueller 1
1 Physical Chemistry, Dresden University of Technology, Dresden Germany
Show AbstractFor the last few years the topic of aerogels is catching more and more the interest of researchers
due to their variety of exceptional properties like high surface area and low densities. Especially
metal based gels are promising for catalytic, sensor or spectroscopic applications. Another
important field of interest is the development of new thermoelectric materials or the improvement
of existing ones. Energy in form of heat, which is generated by power stations and a lot of other
applications, is wasted completely. Thermoelectrics convert this heat energy to electric energy
and the other way around. The efficiency depends on the thermal and electrical conductivity as
well as the Seebeck-coefficient of the material. Having a low thermal conductivity while
maintaining the electrical conductivity and additionally getting a high Seebeck-coefficient is the
challenging task. We here present a thermoelectric aerogel consisting of randomly distributed
parts of gold and lead sulfide. Starting with a perfectly alloyed gold-silver gel formed by gelation
of individual sub 10 nm gold and silver spheres, the final product is obtained by sulfurization and
a cation exchange. The structural properties of the initial gel during the procedure remain
constant. In comparison to previous methods, there is a better distribution of the elements without
any organic stabilizing residues improving the electrical conductivity of the material. Due to the
chain-like network, we create a large amount of grain boundaries which are promising to
decrease the thermal conductivity more than bulkier materials. There is a lot of potential to get a
variety of other thermoelectric materials by extending this method to selenides and tellurides or
changing the metal from lead to bismuth.
9:00 PM - NM3.14.02
Mechanical Properties of Silica Aerogels for Photovoltaic Applications—Input from Modelling and Experimental Work
Romain Cauchois 1 , Marcel Meuwissen 1 , Changjian Shen 2 , Paul Steeman 1 , Damien Reardon 1
1 , DSM Ahead R&D, Eindhoven Netherlands, 2 Performance Materials Research Center, DSM, Shanghai China
Show AbstractThe use of sol-gel derived silica aerogel layers has been reported extensively in the recent past for multiple applications in relation to their improved low-k dielectrics, anti-reflective or bio-compatible properties. Such aerogel coatings are subject to degradation by friction and wear throughout their lifetime due to manual operation, like installation or cleaning operations.
In light of reducing cost and to simplify the process, a single layer large area coating technology package has been developped to produce high volume anti-reflective (AR) coatings, for solar PV module cover glass. This aerogel coating is a thin interference coating (~100 nm) with a low refractive index of 1.3. The thin film low index of refraction is obtained by increasing the void fraction in the coating by making use of hollow silica nanoparticles synthesized from a charged latex polymer template and a binder material. The resulting formulation is deposited and processed as a thin film on a glass substrate.
In this paper, the impact of abrasion on the coating performance over the years is studied by the development of accelerated life tests, which simulates different cleaning operation conditions. The analysis of the surface morphology after abrasion sheds light on the failure mechanisms. According to the conditions used during the test (mild to harsh conditions), several failure mechanisms are observed from a mere modification of the surface roughness up to the total removal of the coating. These mechanisms are responsible for a loss of efficiency of the anti-reflective properties.
A 3D finite element modeling (FEM) approach is used to define guidelines for the development of abrasion-resistant coatings, based on different scenarii like for instance the impact of a structural reinforcement by a hard coat, or the impact of the morphological reinforcement by a variation of the void fraction or the pore size. The result of these simulations indicates that the void fraction of the coating has significantly more impact on the hardness, than for example the void dimension or the hard coat thickness. These predictions are confirmed experimentally using the accelerated abrasion test developed for AR coatings. Since a higher void fraction is directly related to a lower refractive index, the development of the optimum AR coating is a trade-off between its optical and mechanical performance. Therefore, such mechanical reinforcement strategies have to be defined based on the lifetime requirements and the external/environmental conditions.
9:00 PM - NM3.14.03
Preparation and Thermal Conductivity of Silica Aerogel-Based Rigid Board
Kazuma Kugimiya 1 , Yoshimitsu Ikoma 1 , Yasuhiro Hidaka 1
1 , Panasonic Corporation Eco Solutions Company, Kadoma Japan
Show AbstractAerogel has two to three times the performance of conventional insulation boards, requiring only one-third to one-half the space. High thermal insulation performance brings an ideal option for interior applications where space is restricted and thickness of insulation is especially critical. Aerogel is used in rigid boards for insulation and finishing systems in order to relieve weakness of mechanical strength. When preparing rigid board, the penetration of additives into fine pore must be prevented since high performance of thermal conductivity is derived from fine pore structure and high porosity. In this presentation, we report the relationship between the thermal conductivity of silica aerogel-based rigid board and their structure such as distribution of bonding resin and air voids formed between the particles.
First, silica aerogel-based rigid board was prepared by using phenolic resin and styrene/butyl acrylate copolymer as binder. Thermal conductivity of phenolic resin specimen is lower than that of styrene/butyl acrylate copolymer specimen. In case of styrene/butyl acrylate copolymer specimen, the binder covers the surface of aerogel particles uniformly and connects over a broad scope. On the other hand, phenolic resin is scatteringly located on the surface of aerogel particles. This scattered distribution of binder results in decrease of solid conduction via binder layer, leading to lowering thermal conductivity of silica aerogel-based rigid board. Next, we prepared silica aerogel-based rigid board with different packing density and measured their thermal conductivity. The result of density dependence in thermal conductivity indicates that thermal conductivity does not increase monotonically with packing density of rigid board and has the optimal density at around 0.16 g/cm3. X-ray CT images revealed that silica aerogel-based rigid board contains a large amount of voids at around 100 μm in pore diameter. Residual air inside the voids is considered to cause an increase of thermal conductivity silica aerogel-based rigid board. Finally, silica aerogel-based rigid board was prepared by addition of smaller particle at around 100 μm in pore diameter. The resultant rigid board has lower volume ratio of air void compare to original rigid board, leading to decrease the thermal conductivity. The thermal conductivity of silica aerogel board at optimal condition is 14.1 mW/(mK).
In summary, we prepared the silica aerogel-based rigid by hot pressing method and clarified that the distribution of binder and elimination of air voids by controlling of wettability of additives and particle size of aerogel is important for improving the thermal performance of the silica aerogel-based rigid board.
9:00 PM - NM3.14.04
Hierarchical, Tunable Pore Size Polymer Aerogel Capsules for Fusion Targets
Christopher Hamilton 1 , Matthew Lee 1 , Nicholas Parra-Vasquez 1 , Randall Randolph 1 , Tana Cardenas 1 , Derek Schmidt 1 , Brian Patterson 1 , Kevin Henderson 1 , John Oertel 1
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractThe Marble inertial confinement fusion (ICF) campaign at Los Alamos National Laboratory seeks new insights into fusion reactant heterogeneity issues by utilizing target capsules containing polymer aerogels of variable pore size, tunable over an order of magnitude. Here we describe recent progress in the development of deuterated polymer foam capsules in support of Marble. Sacrificial porogen templates within an open-celled, deuterium labeled, poly(divinylbenzene-co-styrene) aerogel matrix, allow low-density foams (ca. 30 mg/mL) with tunable, continuous multimodal pore networks. These foams have been machined into beads via single crystal diamond turning, inserted in plastic ablator shells, gas filled and then fielded on multiple laser platforms.
9:00 PM - NM3.14.06
Direct Ink Writing of Activated Carbon Aerogels
Swetha Chandrasekaran 1 , Patrick Campbell 1 , Cheng Zhu 1 , Fang Qian 1 , Tianyu Liu 2 , Tianyi Kou 2 , Yat Li 2 , Eric Duoss 1 , Theodore Baumann 1 , Christopher Spadaccini 1 , Marcus Worsley 1
1 , Lawrence Livermore National Laboratory, Livermore, California, United States, 2 Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, United States
Show AbstractCarbon aerogels (CAs) are porous solids with an interconnected network of carbon nanoparticles that exhibit high surface area, electrical conductivity, and good structural stability. The CAs are often used as energy dense electrodes in capacitive deionization or supercapacitors for better performance. However, finding the right balance between the pore size and surface area without compromising the mass transport and output power efficiency of the electrodes remains a challenge. Here, we use additive manufacturing (AM) techniques to 3D print macropores in these CAs to improve the same. A critical step for 3D printing the CAs via the direct ink write (DIW) method is to develop a thixotropic resorcinol-formaldehyde (RF) ink. Electrodes with dimension varying from 10’s of mm to cm were printed with the smallest feature size of 250 micron. This approach provides great flexibility to 3D print a wide range of architectures depending on the application. The 3D-printed RF inks are cured, carbonized and later activated to yield ultra-high surface area 3D-printed carbon aerogels.
Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development Grant 16-ERD-051. This work was performed under the auspices of the U.S. Department of Energy by LLNL under contract DE-AC52-07NA27344.
9:00 PM - NM3.14.07
Assembly of Spherical and Finite-Sized One-Dimensional Oxide Structures
Jaswinder Sharma 1
1 Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States
Show AbstractAssembly of spherical and one-dimensional structures is an intriguing research area because of its fundamental importance and practical applications. In this talk, I will present a single step, in situ hierarchical assembly of spherical oxide structures and their potential applications. I will also discuss the assembly of finite-sized one-dimensional oxide structures and the effect of morphology of the building blocks on the assembly process.
9:00 PM - NM3.14.08
Development and Fabrication of Uniform Ultra-Low Density Aerogel Coatings inside Hollow Spheres
Tom Braun 1 , Christopher Walton 1 , Sung Ho Kim 1 , Trevor Willey 1 , Anthony Van Buuren 1 , Bernhard Kozioziemski 1 , Marcus Worsley 1 , Monika Biener 1 , Alexander Chernov 1 , Alex Hamza 1 , Juergen Biener 1
1 , Lawrence Livermore National Laboratory, Livermore, California, United States
Show AbstractFunctional, uniform thin film coatings on the inside of spherical surfaces are increasingly being applied by the scientific community and industry, where they are used in optical devices, time- or site-controlled drug release, heat storage devices, and energetic materials. Hollow spheres lined with ultralow density (< 25 mg/cm3) aerogels have recently gained tremendous interest in the inertial confinement fusion community, where the porous coating on the inside of a millimeter-sized spherical target can serve as a scaffold for the cryogenic deuterium-tritium (DT) fuel ice layer or to bring dopants for diagnostics and nuclear physics experiments in direct contact with the DT fuel. This unprecedented wetted aerogel target design was also recently used to study new ignition regimes with the first ever liquid deuterium-tritium (DT) fuel layer implosion at the National Ignition Facility, Lawrence Livermore National Laboratory.[1]
The fabrication of aerogel coatings in hollow spheres with high coating uniformity, which is crucial for the application performance, requires precise understanding and control over the coating process and its parameters. We have demonstrated that aerogel-lined targets can be made by using prefabricated ablator shells as a mold in which the aerogel film is casted by sol–gel chemistry while the shell is rotated.[2] Conventional computational fluid dynamics (CFD) simulations based on the Navier–Stokes equations and spatio-temporal image analysis provided crucial information on how the foam precursor liquid is distributed in the rotating shell.[3] This required the development of a suitable polymer-based sol-gel chemistry that can be tuned and withstand the forces experienced during the coating and supercritical drying process.[4, 5] The resulting non-shrinking, ultralow density CHx-based polymer aerogel coatings are robust enough to survive wetting with liquid DT and open a new experimental platform for the fields of material, industrial, and environmental science.
Work at LLNL was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.
1. Olson, R.E., et al., Wetted foam liquid fuel ICF target experiments. Journal of Physics: Conference Series, 2016. 717(1): p. 012042.
2. Biener, J., et al., A new approach to foam-lined indirect-drive NIF ignition targets. Nuclear Fusion, 2012. 52(6): p. 062001.
3. Braun, T., et al., In Situ Real-Time Radiographic Study of Thin Film Formation Inside Rotating Hollow Spheres. ACS Applied Materials & Interfaces, 2016. 8(4): p. 2600-2606.
4. Dawedeit, C., et al., Tuning the rheological properties of sols for low-density aerogel coating applications. Soft Matter, 2012. 8(13): p. 3518-3521.
5. Kim, S.H., et al., Exploration of the versatility of ring opening metathesis polymerization: an approach for gaining access to low density polymeric aerogels. Rsc Advances, 2012. 2(23): p. 8672-8680.
9:00 PM - NM3.14.09
ESR Detection of X- Ray-Induced Free Radicals in Crosslinked Silica Aerogels
Firouzeh Sabri 1 , Benjamin Walters 1 , Ramon Leon 2 , Shah Jahan 1
1 Physics and Materials Science, University of Memphis, Memphis, Tennessee, United States, 2 Business Analytics and Statistics, University of Tennessee, Knoxville, Knoxville, Tennessee, United States
Show AbstractAerogels have been investigated extensively for aerospace applications and used in various capacities. In recent years, aerogels have also been studied for biomedical and biological applications. In both environments, exposure to radiation such as X-rays, gamma rays, and ultraviolet radiation is inevitable and it is expected that material properties will be affected to various degrees as a result of radiation exposure. A detrimental consequence of radiation exposure is the generation of free radicals which have been known to lead to material degradation and premature aging. In this study, the authors have studied the effect of X ray irradiation on polyurea-crosslinked silica (PCSA) aerogels maintained at room temperature. PCSA samples were exposed to approximately 170- and 500-Gy X-irradiation in air and oxygen free environments and characterized using electron spin resonance (ESR) technique, also known as electron paramagnetic resonance (EPR). ESR is a technique that can directly detect and quantify unpaired electrons in atomic or molecular systems, providing the unique ability to directly detect free radicals. Results obtained for PCSA were compared with those collected from polyether-ether ketone (PEEK), and ultra-high molecular weight polyethylene (UHMWPE), irradiated and stored under the same conditions as the PCSA specimens. PEEK is known to be very radiation resistant, while UHMWPE is known to undergo significant molecular and physical changes upon radiation exposure, so were used as a basis of comparison to the unknown PCSA. Results showed significant quantities of free radicals produced in PCSA due to X-irradiation. Levels detected in PCSA were in-between those detected in PEEK and UHMWPE. The effect of exposure environment (air versus nitrogen) and storage conditions (air versus nitrogen) on free radical creation and survival was also tested and will be reported.
9:00 PM - NM3.14.11
On-Sun Demonstration of a Solar-Thermal Aerogel Receiver (STAR)
Lee Weinstein 1 , Thomas Cooper 1 , Sungwoo Yang 1 , Bikram Bhatia 1 , Lin Zhao 1 , Elise Strobach 1 , George Ni 1 , Svetlana Boriskina 1 , Evelyn Wang 1 , Gang Chen 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractSolar energy is a critically important renewable energy technology, however solar energy technologies must be paired with storage to provide a constant supply of electricity due to the intermittency of sunlight because of weather and diurnal cycling. Solar-thermal systems, in which sunlight is converted to high temperature heat before being converted to electricity, are promising in this regard, as heat can be stored more easily and inexpensively than electricity. We have developed optically transparent, thermally insulating silica aerogels, which enable a novel Solar-Thermal Aerogel Receiver (STAR). A transparent aerogel layer covering the high temperature absorber will insulate it from thermal losses while still allowing sunlight to reach the absorbing surface. STAR offers a number of advantages compared to traditional vacuum tube receivers: it achieves high efficiency without the use of spectrally selective coatings or vacuum, which could lead to better reliability and enables non-cylindrical receiver geometries. This flexibility in geometry is particularly useful for receivers paired with linear Fresnel reflector (LFR) concentrating optics. In order to demonstrate performance in on-sun operation, we have built a prototype 1-m long, 10-cm wide STAR, along with a 33x concentration ratio LFR array. In this presentation we will report the optical and thermal efficiencies achieved by the STAR prototype. This work is supported by the U.S. Department of Energy through Advanced Research Projects Agency−Energy (ARPA-E) Award No. DE-AR0000471.
9:00 PM - NM3.14.12
In Situ Nanoparticle Encapsulation in Aerogels by Ultraviolet Photopolymerization for Targeted Drug Delivery Applications
Daniel Denmark 1 , Charlotte Charlotte Gladney 2 , Robert Hyde 1 , Pritish Mukherjee 1 , Sarath Witanachchi 1
1 , University of South Florida, Tampa, Florida, United States, 2 Physics, University of Alabama, Tuscaloosa, Alabama, United States
Show AbstractStimuli responsive aerogels, such as poly(N-isopropylacrylamide), are widely used for triggered release when heated beyond the body temperature of approximately 32 °C. Conventional therapeutic techniques treat the patient by delivering a biotherapeutic to the entire body rather than the target tissue. In the case of chemotherapy, the biotherapeutic is a drug that kills healthy and diseased cells indiscriminately which can lead to undesirable side effects. With targeted drug delivery devices, biotherapeutics can be delivered directly to the diseased tissue significantly reducing exposure to otherwise healthy tissue. Inclusion of magnetic nanoparticles along with biotheraputics within capsules of aerogels enables the guidance of the drugs to specific sites. Once at site, rf-radiation heating of the magnetic nanoparticles in capsules cause the aerogel to contract, allowing the release of the drugs. This research presents a study conducted to explore non-toxic, biocompatible, non-residual, photochemical methods of creating stimuli responsive micro-aerogels to advance the targeted drug delivery field. Ultraviolet photopolymerization process used in forming aerogel capsules is efficient, while ensuring safety by using only biocompatible substances. The reactants decided upon for polymer fabrication were N-isopropylacrylamide as the monomer, methylene bisacrylamide as the cross-linker, and Irgacure 2959 as the ultraviolet photo-initiator. The magnetic nanoparticles for encapsulation were 6 – 8 nm in diameter and composed of cobalt-doped magnetite to enable remote delivery and enhanced triggered release properties. A low-cost, scalable, and rapid, custom ultraviolet photo-reactor with in-situ, spectroscopic monitoring system is used to observe the synthesis as the sample undergoes photopolymerization. Transmission Electron Microscopy confirmed the size-tunable micr-aerogel spheres between 50 and 200 nm by varying the ratio and concentration of the reactants. Nano-Tracking Analysis indicates that the microgels exhibit minimal agglomeration as well as provides a temperature-dependent particle size distribution. Dynamic light scattering studies of the aerogels under rf-radiation will be discussed.
9:00 PM - NM3.14.13
Nanoporous Cyclic Organic Aerogels for Selective Carbon Dioxide Capture
Eric Leonhardt 1 , Tiffany Williams 2 , Guorong Sun 1 , Karen Wooley 1
1 Chemistry, Texas A&M University, College Station, Texas, United States, 2 , NASA Glenn Research Center, Cleveland, Ohio, United States
Show AbstractThe proposed work aims to develop advanced synthetic methodologies that afford nanoporous materials with selective uptake affinity towards carbon dioxide and large gas storage capacities. The expected significance of this work is the expansion of potential applications of NASA-designed aerogels to carbon dioxide capture, with increased customization potential for these materials by the incorporation of an adjustable cyclic backbone, and the elucidation of important structure-property relationships for these systems. Cyclic polymers show remarkably different behaviors than their linear counterparts, and are expected to provide a highly tunable system for removing impurities such as carbon dioxide from breathing air aboard space vessels. The tunability will be further enhanced by the construction of aerogel-based molecular brush polymer networks, which are expected to behave significantly differently from current systems, and will allow for pre-established molecular design parameterization facilitated by the covalent connectivity combined with solution- and solid-state assembly processes. Cyclic polymers will be achieved by ring-expansion metathesis polymerization (REMP), and a significant effort will be directed towards modifications of the reaction conditions to improve control of this polymerization. Increased density of nitrogen-containing functional groups, shown to be efficacious for selective carbon dioxide uptake, will be achieved by synthetic and post-processing techniques. A library of cyclic aerogels with varying backbone length, compositional fraction, and polyimide molecular weights will be prepared and characterized to determine network architecture and experimentally obtain carbon dioxide uptake capacities/selectivities.
9:00 PM - NM3.14.14
Ultralow-Density Transparent Boehmite Nanofiber Aerogels and Cryogels for Nanoglue
Gen Hayase 1
1 , Tohoku University, Sendai Japan
Show AbstractMonolithic aerogels have been attracting interest from researchers of wide fields. Especially, silica aerogels show unique properties such as low thermal conductivity, high surface area, visible-light transparency, and low refractive index. To prepare those materials, supercritical drying process is needed to avoid from collapse and non-uniform shrinkage which cause light scattering. This high-cost process has prevented from industrial uses and many researchers have tried to find better ones.
In this presentation, I introduce ultralow-density boehmite nanofiber aerogels and cryogels. To prepare aerogels, I used a sol-gel reaction under basic conditions. The obtained samples via supercritical drying process showed visible-light transmittance and low refractive index. To prepare the cryogels, boehmite nanofiber dispersed sol was frozen by liquid nitrogen and dried under vacuum condition. Those cryogels showed ultralow-density and high visible-light transmittance when the size was smaller than several millimeters in diameter. By adding functional materials such as chromic ones to the starting sol, they were dispersed into the microstructure. Optical properties and this “nanoglue” function can be expected to be used for preparing new sensing materials.
9:00 PM - NM3.14.15
Nanoparticle Chalcogenide Aerogels—Assemblies via Covalent Crosslinking
Indika Hewavitharana 1 , Stephanie Brock 1
1 Chemistry, Wayne State University, Detroit, Michigan, United States
Show AbstractThe insulating organic ligands used in colloidal synthetic routes preclude efficient electrical transport in assemblies, limiting potential application in solid state devices. Although, the replacement of organic ligand shells around the colloidal semiconductor nanoparticles (NPs) with chalcogenides (S2-, Se2- and Te2-) or chalcogenidometallates (SnS44-, Sn2Se64-, In2Se42-, Ge4S104-, etc.) enhances the electronic coupling interactions between NPs, electrostatic repulsion forces between chalcogenide/ chalcogenidometallate ions adversely affects the self-assembly of NPs into robust 2 and 3D networks. We seek to develop a method to tune the interfacial chemistry and overcome the negative electrostatic repulsion barrier by forming electronically connected bridges covalently crosslinked by metal cations. We report the formation of crosslinked gels of PbTe by ligand exchange of PbTe NPs with S2-, or SnS44-, and subsequent treatment with Sn4+ ions. The nature of the interparticle interactions and charge transport relative to NP gels formed by oxidative crosslinking will be discussed.
9:00 PM - NM3.14.16
Challenges in Structural and Thermal Analysis of Aerogels
Christian Scherdel 1 , Gudrun Reichenauer 1 , Katrin Swimm 1 , Stephan Vidi 1
1 , Bavarian Center for Applied Energy Research, Wuerzburg Germany
Show AbstractThe extraordinary physical and structural properties (high porosity, low thermal conductivity, 3D-network of cross-linked particles etc.) of aerogels can be a challenging task with respect to reliable characterization.
For the determination of structural properties, such as mesoporosity, gas sorption is usually performed. However, strong compressibility effects during analysis (compression up to 50 vol%) may cause highly erroneous pore size distributions. When sufficient equilibrium is reached, a correction of the isotherm is necessary to obtain the “true” pore sizes of aerogels in their intrinsic state. This approach was verified by small angle scattering techniques, which are not yet standardized for the determination of pore sizes.
For very low thermal conductivities such as for aerogels, care has to be taken that the instrumentation used is actually suitable for the sample under investigation. Additionally, the ability to perform measurements close to application conditions (cryogenic to high temperature, vacuum to increased gas pressure, external load, etc.) and the option to separate the different contributions to the overall thermal transport in the aerogel is crucial for target-oriented material development and optimization. We show how detailed analysis of heat transport allows understanding the underlying thermal transport mechanisms and thus the optimization of aerogel based materials for well-defined applications. In the examples the impact of radiative, solid phase and gas phase heat transport is discussed. More recent analysis of coupling effects coming into play when the backbone consists of particles connected by small necks or not fully cross-linked mass is present in the system, as it is typically found in aerogels. Coupling also affects the estimation of pore sizes suitable to suppress gas phase transport.
9:00 PM - NM3.14.17
Aerogels of Chitosan—Relation between Chitosan Solution Properties and Nanostructure of the Aerogel
Gonzalo Santos-Lopez 1 , Jaime Lizardi-Mendoza 1 , Waldo Arguelles-Monal 1 , Elizabeth Carvajal-Millan 1 , Yolanda Lopez-Franco 1 , Maricarmen Recillas-Mota 1
1 Grupo de Investigación en Biopolímeros, Centro de Investigación en Alimentación y Desarrollo A.C., Hermosillo, Sonora, Mexico
Show AbstractFive different types of aerogeles of chitosan (Cs) where obtained. Each one was obtained by supercritical drying of physical gels formed from solution with different solvents: with aqueous hydrochloric acid (CsHc), acetic acid (CsHa), sodium formaldehyde bisulfite (CsFb) and with two ionic liquids, 1-ethyl-3-methylimidazolium acetate (CsEm) and 1-butyl-3-methylimidazolium acetate (CsBm). The intrinsic viscosity [η] of each Cs-solvent system was determined. The acid systems, CsHc and CsHa, reach [η] values between 5000 and 5200 mL/g, this correspond to an hydrodynamic volume where the polysaccharide molecules adopt expanded coil conformations due to intramolecular electrostatic repulsions. The CsFb system has a [η] of 750 mL/g, in this case for the same Cs molecules, the net charge of the chains is reduced resulting in a smaller hydrodynamic volume that in aqueous acid solutions. The CsEm and CsBm are non-aqueous systems, apparently no polyelectrolyte effects affecting the hydrodynamic volume are observed resulting in a relaxed coil conformation with smaller intrinsic viscosity values. Miscible non-solvent vapor diffusion was used produce physical gels from each type of Cs solution. The liquid phase of these gels was substituted by ethanol and then were dried with supercritical CO2 to obtain aerogels. No chemical modification of the chitosan nor solvent residuals are observed in the FTIR spectra of the aerogels. All the obtained aerogels show internal mesoporous structure, with a distribution of pores in the 15-40 nm range and 160-220 m2/g of surface area. However, different types of nanostructures were revealed by SEM, chitosan aerogels from acid solutions, CsHc and CsHa, have agglomerated granular structure, contrasting CsFb aerogels show a fibrous nanostructure. The aerogels from ionic liquids, CsEm and CsBm, are similar to CsFb aerogels but with more compact structure. The solution properties of chitosan affect gel formation processes and the setting of the molecules in solid state forming distinctive nanoscale porous structures in aerogels from the same chitosan sample.
9:00 PM - NM3.14.18
Acemannan Aerogels—Promising Biofunctional Scaffolds
Daniel Miramon-Ortiz 1 , Jaime Lizardi-Mendoza 1 , Waldo Arguelles-Monal 1 , Elizabeth Carvajal-Millan 1 , Francisco Goycoolea-Valencia 1 , Yolanda Lopez-Franco 1 , Veronica Mata-Haro 1
1 , Centro de Investigación en Alimentación y Desarrollo A.C., Hermosillo Mexico
Show AbstractAerogels have diverse properties that are appealing for medical applications. Combining these properties with those of natural polymers, like polysaccharides, may increase the applicability of aerogels in life sciences. Acemannan (AC) is a biocompatible and biodegradable polysaccharide that can promote wound healing and activate macrophages, inducing the recognition of foreign antigens (viruses, bacteria). A dressing type aerogel biomaterial with distinctive features suitable for wound healing could be obtained with AC. Pursuing this goal, herein is reported the isolation of acemannan (AC) from aloe vera parenchyma, its main characteristics and aerogel formation. The isolated sample was positively identified as acemannan by Fourier transformed infrared spectroscopy. Its molecular weight was determined at 1,500 kDa by SEC-MALLS. Gelling of AC was promoted by vapor diffusion of two different miscible non-solvents. Two types of monolith-disc physical hydrogels were obtained. The liquid phase of the gels was substituted with acetone. The obtained acetogels were dried by supercritical CO2. The obtained AC aerogels are highly porous materials with mesoporous structure (15-40 nm pore size), low density (0.1–0.46 g/cm3) and high specific surface area (150-300 m2/g). This results suggest that these type of materials can provide high liquid absorption rates and enhanced interphase interaction in living tissues that could lead to a faster and efficient wound healing.
9:00 PM - NM3.14.19
Hierarchical, Tunable Pore Size Organic and Inorganic Aerogels from Sacrificial Templates
Stephanie Edwards 1 , Matthew Lee 1 , Nicholas Parra-Vasquez 1 , Miguel Santiago Cordoba 1 , Christopher Hamilton 1
1 , Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractWe have recently utilized orthogonal chemistries to produce hierarchical aerogel materials, having native porosity on the nanoscale, and secondary porosity templated by sacrificial porogens, allowing access to a size range over an order of magnitude. This method is loosely based on inverse opal technology, wherein glassy aggregates of porogenic particles are used.
We have templated macropores in organic DVB/polystyrene sol gels using silica microballoons; likewise, we have introduced macroporosity in silica aerogels utilizing PMMA particles.
This method is amenable to a wide range of matrices and chemistries, as it relies solely on fractionation of porogen in a sol, followed by orthogonal etching to remove the template.
LA-UR-16-28144
Symposium Organizers
Stephen Steiner, MIT
Stephanie Brock, Wayne State University
Alexander Eychmueller, TU Dresden
Nicholas Leventis, Missouri University of Science and Technology
Symposium Support
Aerogel Technologies, LLC
Aspen Aerogels, Inc.
BASF Polyurethanes GmbH
Blueshift
JEOL USA, Inc.
NASA–Glenn Research Center
NM3.15: Processing and Part Fabrication—Challenges and Opportunities
Session Chairs
Marc Hodes
Stephen Steiner
Friday AM, April 21, 2017
PCC West, 100 Level, Room 105 BC
9:00 AM - *NM3.15.01
Engineering Bacterial Cellulose Nanocomposites—Aerogel-Inspired Biopolymers
Anna Roig 1 , Muling Zeng 1 , Deyaa Youssef 1 , Sebastia Parets 1 , Judit Fuentes 1 , Jordi Floriach 1 , Anna May-Masnou 1 , Anna Laromaine 1
1 , ICMAB-CSIC, Bellaterra Spain
Show AbstractIndustries, governments and consumers increasingly request exploring greener, sustainable and natural resources for the fabrication of advanced complex materials. Cellulose constitutes an almost inexhaustible biopolymer, being the most abundant renewable polysaccharide produced in the biosphere. Although cellulose is predominantly obtained from plants, it can also be synthesized by bacteria, algae and fungi. In particular, bacterial cellulose (BC) produced by microbial fermentation has the same molecular formula as plant-derived cellulose but, in contrast, is a pure biopolymer that exhibits a high degree of polymerization and crystallinity. Importantly, BC does not contain lignin and hemicellulose, two non-degradable components and potential sources of toxicity present in plant-derived cellulose. BC also has high porosity, transparency in the UV-NIR and a high water holding capacity. Moreover, a very unique characteristic of BC is the possibility to interfere on its micro(nano)structuration and shape during the bacterial synthesis. Thus, the biosynthesis of cellulose offers to materials scientists a model biopolymer to study structure, topography and new bottom-up approaches to fabricate nanocomposites.
Bacterial cellulose is characterized by a three-dimensional architecture consisting of cellulose fibers forming an interconnected open porous network, it thus comply with the definition of what we understand as an aerogel-like material. I will present the production and characterization of cellulose films and the impact that the film drying method has on its microstructure, porosity, wettability, transparency and mechanical properties. I will also present potential strategies to develop value-added engineered nanocomposites of bacterial cellulose by anchoring inorganic nanocrystals on its fibers. As a model system of a renewable biopolymer these new bacterial cellulose nanocomposites will provide the proof of concept for devices or products.
Zeng et al. Journal of Materials Chemistry C 2 (2014) 6312-6318 DOI: 10.1039/c4tc00787e
Zeng et al. Cellulose (2014) 21 4455–4469 DOI 10.1007/s10570-014-0408-y
9:30 AM - NM3.15.02
Modelling of the Extraction Processes for Aerogel Production
Irina Smirnova 1 , Alberto Bueno Morales 1 , Ilka Selmer 1 , Raman Subrahmanyam 1 , Pavel Gurikov 1
1 , TU Hamburg-Harburg, Hamburg Germany
Show AbstractAerogels based on natural polymers have a high potential for different applications, especially for life science, due to their biocompatibility and sustainable source of raw materials. However, the production of such aerogels is still limited to the lab scale. The scale up of the corresponding processes requires deeper understanding of all process steps involved in the transformation of polymer-based hydrogels to aerogels. A reliable model allowing the adequate description and scale up of the solvent exchange and supercritical drying for this type of aerogels is still missing. Therefore the aim of this work is to build such a model taking into account the most relevant phenomena during the solvent extraction, such as diffusive and convective solvent flow during extraction steps; density change during the solvent exchange and supercritical drying; shrinkage of the gel; mutual solubility of the solvents involved at different pressure and temperature; geometry of the gel. The model takes into account both the mass transfer, thermodynamic equilibrium data as well as solvent-polymer interactions. It helps to identify the optimal process conditions to minimize the gel shrinkage and the drying time. Based on the experimental data for alginate and protein aerogels, all relevant model parameter are estimated and the model is validated at different process conditions. Finally, recommendations for the optimal process conditions for certain aerogel types are given.
9:45 AM - NM3.15.03
Practical Considerations in Scale-up of Aerogel Monoliths
Ryan Nelson 1 , Justin Griffin 1 , John Schneider 1 , Stephen Steiner 1
1 , Aerogel Technologies, South Boston, Massachusetts, United States
Show AbstractA vast number of organic and inorganic aerogels have been described in the literature, but few of these have been transitioned to large monoliths (e.g. 30 centimeter panels). Typical materials produced in lab scale aerogel formulations research are on the order of 1-2 centimeters in diameter and are only reproduced a handful of times. However, many challenges arise when trying to make materials even a few centimeters larger and in a repeatable and sustainable manner. A key aspect of our business is scaling monolithic aerogel materials into viable products. In particular, we have focused on polymer aerogel formulations, and developed methods to produce large sizes and quantities of these materials. Large sizes create new challenges in each aspect of production. Starting with the chemistry, recipes need to be adjusted to prevent defects that are not obvious at the small scale. Casting strategies and molding materials are as important as monomer, solvent selection, and catalyst concentrations for controlling the gel structure on the macro and nano level. Phenomena such as bubble formation, material warping and mold stiction that are normalized out in syringes and beakers have a much more noticeable effect in larger form factors. In addition, aspects such as gel time, homogeneity and density differ depending on the size of the gel domain. After gelation, solvent exchange steps and drying processes can lead to further significant shrinkage or warping if not precisely controlled. Further shape control or machining of the dry aerogel is equally non-trivial but often essential for many applications. Methods for scaling to large monolithic parts, and lessons learned with different aerogels will be discussed.
10:00 AM - NM3.15.04
Hazard Analysis of a Rapid Supercritical Extraction Process for Aerogel Fabrication
Bradford Bruno 1 , Ann Anderson 1 , Mary Carroll 1
1 , Union College, Schenectady, New York, United States
Show AbstractDue to the high pressures required, aerogel manufacturing via supercritical solvent extraction involves risks beyond those associated with the chemical preparation of the aerogel precursors themselves. Pressure-related risks can be aggravated if the solvent to be extracted is combustible. One well-known incident [1] that illustrates the potential risks involved an explosion during supercritical methanol extraction from a pressure vessel during the large-scale production of silica monoliths.
Many conventional aerogel monolith manufacturing techniques now include several time-consuming steps to exchange the solvent in the gel for a non-combustible solvent (typically CO2) prior to supercritical solvent extraction. In contrast, rapid supercritical extraction (RSCE) techniques extract the solvent mixture formed during gelation (typically an alcohol or alcohol/water mixture) directly. On the laboratory scale, an RSCE method involving a contained mold in a hydraulic hot press [2,3] has been used safely. This technique is inherently scalable, which raises legitimate safety concerns associated with RSCE of larger solvent volumes.
To address these concerns a risk and safety analysis was conducted on this RSCE method. The analysis consists of a Preliminary Hazard Analysis (PHA) conducted based on two sub-analyses: a Failure Mode and Effects Analysis (FMEA), and an Energy Trace and Barrier Analysis (ETBA) [4]. Hazard severity categories and hazard probability levels in accordance with MIL-STD-882 [5] are assigned to identify the overall risk criteria for key failure modes. Comparisons are made to conventional supercritical extraction techniques that involve the use of large pressure vessels. Key findings include that the most significant risks are proportional to the overall volume of flammable solvent being extracted, that the RSCE process has significant inherent advantages over conventional techniques in this regard, and that with suitable barriers and safety procedures the risk associated with this RSCE method can be reduced to acceptable levels.
[1] Henning, S., “Large Scale Production of Airglass.” Springer Proceedings in physics/Aerosols Vol. 6, 38-41.
[2] Gauthier BM, Bakrania SD, Anderson AM & Carroll MK, 2004, “A Fast Supercritical Extraction Technique for Aerogel Fabrication.” J. Non-Crystalline Solids, 350, 238-243.
[3] Carroll MK, Anderson AM, & Gorka CA, 2014 “Preparing Silica Aerogel Monoliths via a Rapid Supercritical Extraction Method.” J. of Visualized Experiments, 84, DOI: 10.3791/51421.
[4] Vincoli, J. W. Basic Guide to System Safety, 2nd ed. Wiley Interscience, 2006.
[5] U.S. department of Defense (March 1984) MIL-STD-882E 2012: Department of Defense Standard Practice: System Safety, U.S. Government Printing Office, Washington DC.
10:15 AM - NM3.15.05
Fluoride Aerogels Based on AlF3—Direct Preparation, Nanostructure and Some Surface Characteristics
Tomaz Skapin 1
1 , Jozef Stefan Institute, Ljubljana Slovenia
Show AbstractSystematic research of nanoscopic inorganic solid fluorides intensified considerably in the new millennium. Key achievements in this field are closely related with the development of novel synthetic methodologies that operate under softer/milder reaction conditions and allow a better control over the nanostructure of the fluorides formed.[1,2] Some specifics and limitations encountered during the preparation of nanostructured fluorides will be pointed out in the preface.
Within our investigations in this field, a modified solvothermal methodology in non-aqueous media for the preparation of very porous materials based on AlF3 has been developed. This solvothermal approach is highly versatile and allows the preparation of fluorides with distinctively different porosities, i.e. in the form of compact xerogels or voluminous aerogels. Preparation of the latter type of materials represents the first case of a direct preparation of extremely voluminous AlF3-based aerogels.[3] The work introduces therefore an entirely new class of inorganic aerogels – fluoride aerogels. As found out, bulk structure of the AlF3-based products strongly depends on the shape, size and spatial arrangement of the primary nanoparticles. These characteristics of fluoride nanoparticles can be effectively controlled by a proper combination of solvent(s) and temperature regimes applied throughout the preparation. Under optimal conditions, the applied procedure allows the preparation of regularly shaped and uniformly sized elongated fluoride nanoparticles that are loosely entangled in very open aerogel structures. In addition to nanoscopic and bulk structural aspects, acidity of these materials in conjunction with catalytic behaviour will also be presented.
References: [1] Functionalized Inorganic Fluorides, A. Tressaud Ed., John Wiley & Sons, 2010; [2] T. Skapin et al., J. Fluorine Chem. 130 (2009) 1086–1092 & 132 (2011) 703–712; [3] A. Štefančič et al., Dalton Trans. 44 (2015) 20609–20617.
10:30 AM - NM3.15.06
Preparation of One Square Foot Aerogel Monolith
Mamoru Aizawa 1
1 , Tiem Factory Inc., Kyoto Japan
Show AbstractIn 1931, Kistler prepared aerogel via supercritical drying [1] . Several forms of aerogels, i.e. monolith, powder, blanket , have been prepared with supercritical drying.
In 1992, Smith, Deshpande and Brinker synthesized aerogels via ambient pressure drying [2] . Because of the capillary force which arose during ambient pressure drying, aerogels could be easily collapsed and it was difficult to obtain monolith.
Kanamori, Aizawa, Nakanishi and Hanada reported preparation of transparent and low-density aerogel monolith from methyltrimethoxysilane under the co-presence of surfactant via ambient pressure drying [3].
This time, one sq.ft flawless aerogel monolith was prepared via ambient pressure drying. The gel was made from methyltrimethoxysilane and BASF's Pluronic PE-10500 as a surfactant.
Density of the aerogel monolith was 0.11g/cm3. Transmittance of 1cm thickness monolith at 550nm was 90%. Its thermal conductivity was 13 mW/mK.
References
[1] S.S.Kistler, Nature 1931, 127, 741.
[2] D.M.Smith, R.Deshpande, C.J.Brinker, "Better Ceramics Through Chemistry V": Mater.Res.Soc.Symp.Proc. 1992, p.567.
[3] K.Kanamori, M.Aizawa, K.Nakanishi, T.Hanada, Adv.Mater., 2007, 19, 1589.
10:45 AM - NM3.15.07
An Introduction to Aerogels for Use in High Energy Density Plasma Physics Experiments at AWE Target Fabrication
Ian Hayes 1 , Gareth Cairns 1 , Glenn Leighton 2 , Christopher Shaw 2 , Paul Jones 2 , Alberto Valls Arrufat 2 , Jakub Sitek 2 , Magdalena Budziszewska 2 , Clement Lopez 2 , Aymeric Nguyen 2
1 , AWE, Reading United Kingdom, 2 , Cranfield University, Milton Keynes United Kingdom
Show AbstractThe development of aerogel materials for use in plasma physics experiments presents novel challenges. A wide variety of aerogels in a variety of geometries are required for high energy density campaigns, including silica and metal oxides.
AWE uses two main manufacturing techniques for aerogel synthesis; ambient temperature and high temperature critical point drying. The specifications for these aerogels includes strict tolerances on density, uniformity, surface finish and contaminates such as carbon, hydrogen and high ‘Z’ inclusions. In producing material for targets AWE casts aerogels to the required sizes, however further processing steps such as conventional, diamond and laser machining are required prior to assembly into finished products for use in plasma physics experiments.
This paper provides an overview of the AWE aerogel capability and the collaborative work carried out with Cranfield University in support of forming metal oxide aerogels using epoxides.
NM3.16: Characterization
Session Chairs
Nicholas Leventis
Anna Roig
Friday PM, April 21, 2017
PCC West, 100 Level, Room 105 BC
11:45 AM - *NM3.16.01
Towards Rigorous Measurements and Modeling of Supercritical Carbon Dioxide Drying of Sol Gels
Marc Hodes 1 , Hy Dinh 1 , John Moses 2 , Veronica Wilson 2 3 , John Hannon 2
1 Department of Mechanical Engineering, Tufts University, Medford, Massachusetts, United States, 2 , CF Technologies, Hyde Park, Massachusetts, United States, 3 Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractMany silica-based wet (sol) gels are dried using supercritical carbon dioxide to convert them to an aerogel in order to avoid exposing their skeleton to capillary forces. However, the kinetics of this process have not been rigorously modeled due to a lack of available thermophysical property data for the mixtures and a failure to properly capture the effects of “suction” and “spillage” of carbon dioxide into the wet gel and gel fluid into the carbon dioxide, respectively. We discuss the apparatuses being constructed to measure density, viscosity and molecular and Soret diffusion coefficients in carbon dioxide-solvent mixtures as a function of temperature, pressure and composition. Importantly, the measurement techniques selected allow us to measure these properties over the entire range of solvent concentrations. We then provide a formulation to solve the coupled forms of the Navier Stokes equations, species equation and continuity equation for a compressible medium governing supercritical carbon dioxide drying of wet gels such that suction and spillage effects are captured. The predictions of the model are compared to drying rates measured continuously throughout the entire process. Finally, we discuss how, once densities and viscosities have been measured as a function temperature, pressure and composition, metrology may be designed to continuously monitor drying rates during the aerogel production process.
12:15 PM - NM3.16.02
Effective Characterization of Mechanical and Thermal Properties of Mechanically Strong Aerogels
Justin Griffin 1 , Ryan Nelson 1 , Stephen Steiner 1
1 , Aerogel Technologies, Boston, Massachusetts, United States
Show AbstractMechanically strong polymer aerogels are promising materials for use as lightweight plastics replacements in aviation interiors, automotive engineering, and structural insulated panels in construction, exhibiting decent strength and stiffness properties while simultaneously offering superlative thermal insulating and soundproofing benefits. However, a number of very good lightweight high-strength engineering materials such as foams and natural materials are readily available, making commercialization of polymer aerogels not straightforward. Accurate characterization of the mechanical properties of strong polymer aerogels is critical in order to compare their value proposition to existing materials including foams and plastics on a consistent basis. The stress-strain behavior of strong aerogels in compression is non-ideal, and thus difficult to describe within the constraints of traditional testing standards. In particular, compressive strength and yield stress are ill-defined and not consistently reported in the literature. We calculated the Young’s modulus and compressive strength of polymer aerogels of various compositions including polyureas, polyurethanes, polyimides, polyamides, and silica x-aerogels over various densities using ASTM standards for plastics, cellular plastics, and foams as well as recently developed techniques that have not yet been codified as standard. Analyses are compared and relative merits of each discussed. Trends in strength and stiffness as a function of composition and density will be presented drawing from experimental and literature data. Comparison between compressive and tensile behavior will be presented. A new standard for mechanical characterization that takes into consideration the mechanical behavior of aerogels will be proposed. In addition to mechanical characterization, surprising trends in thermal conductivity across different backbone compositions will be presented. Dependence of thermal conductivity on density, morphology, and backbone composition will be discussed and contrasted with mechanical properties.
12:30 PM - NM3.16.04
Adsorption on Aerogels—Thermodynamic Study by Supercritical Fluid Chromatography
Pavel Gurikov 1 , Irina Smirnova 1
1 , Hamburg University of Technology, Hamburg Germany
Show AbstractHaving extremely high specific surface, large pore volume and open pore structure, aerogels have been recognized as thermal insulators, effective adsorbents, energetic materials, carrier for active compounds and in many other fields. One important way to impart new quality to aerogels is adsorption on their surfaces or crystallization in their pores from supercritical solutions. Rational implementation of these processes requires a measure of adsorption interaction between aerogel backbone and a solute in the supercritical phase.
In this work packed column supercritical fluid chromatography (SFC) was used to measure retention of several organic solutes on aerogels. Inorganic (silica) and several biopolymer aerogels microspheres were prepared and packed into a column to be used as stationary phases. Model compound (naphthalene) and drugs (ketoprofen, beclometasone and others) were used as solutes. Supercritical carbon dioxide and its mixtures with modifier were used as mobile phases.
The van’t Hoff analysis was used to derive enthalpy and entropy of adsorption from the retention data. Temperature and pressure of the mobile phase were varied as to reveal influence of the mobile phase density on the adsorption equilibrium. Adsorption from sc-CO2/modifier mixtures is viewed as a competitive process where solute adsorbs both on free active sites and those occupied by modifier. A mixed retention model was formulated and used to interpret retention behavior. This model allows to estimate enthalpy and entropy of adsorption of the solute from pure sc-CO2 using retention from sc-CO2/modifier mixtures.
These results are discussed and compared with data available for xerogels, active carbon and commercial stationary phases. Comparison indicates that in contrast to adsorbents with lower specific surfaces, adsorption on aerogels can be in certain cases controlled by changing fluid density. Relation between loading and adsorption quantities is also discussed.
NM3.17: Biomedical and Bionic Applications
Session Chairs
Alexander Eychmueller
Hongbing Lu
Friday PM, April 21, 2017
PCC West, 100 Level, Room 105 BC
2:30 PM - *NM3.17.01
Aerogels as Scaffolds—Response of PC 12 Neuronal Cells to Surface Topography and Substrate Stiffness
Firouzeh Sabri 1 , Kyle Lynch 1 , Omar Skalli 2
1 Physics and Materials Science, University of Memphis, Memphis, Tennessee, United States, 2 Biological Sciences, University of Memphis, Memphis, South Dakota, United States
Show Abstract
Synthetic biomaterials offer advantages over biological materials because their mechanical, chemical, and surface properties can be fine-tuned to cater to specific needs that are unmet by biological materials. The light weight and topographically rich nature of aerogels makes this class of materials an attractive candidate as a biomaterial for biomedical applications. Recent studies have demonstrated the biocompatibility and biostability of aerogels, in particular, crosslinked silica aerogels both in vitro and in vivo environments. More recently polyurea crosslinked silica aerogels were used as a test bed to attach and grow PC 12 neuronal cells. In this study the authors have thoroughly investigated the effect of the polyurea crosslinked silica aerogel surface roughness and substrate stiffness on the response of PC 12 neuronal cells. Specifically, the cell cluster size, density, and the average neurite length grown on aerogel substrates was measured and compared with the behavior of PC 12 cells on tissue culture plastic petri dishes used as control for this study. It was observed that on average PC 12 cells extended longer neurites on aerogel substrates compared to the control substrates. This has been attributed to the aerogel substrate stiffness and surface roughness. While the exact mechanism(s) that lead(s) to this outcome is not yet fully understood, it demonstrates the applicability of aerogels to the biomedical field.
3:00 PM - NM3.17.02
Polymer Thermoelectric Aerogels for E-Skin Sensors
Shaobo Han 1
1 , Linköping University, Norrköping Sweden
Show AbstractElectronic skin is an artificial materials integrated with electronic devices to mimic the function of the skin. One of the function is sensing the mechanical pressure and temperature; which is essential as it is a protection to the body. Hence, we are investigating a novel concept for sensing pressure and temperature simultaneously and target applications such as medical applications (prosthesis) and robotics [1]. We design elastic conducting polymer aerogels as material whose electrical resistance changes with the pressure and the thermoelectric voltage changes with the temperature [2]. The aerogel is prepared by freeze drying the conducting polymer PEDOT:PSS mixed with cellulose nanofibrills and a elastomeric silane crosslinking agent. We optimize the pressure and temperature sensitivity of the aerogels by various post chemical treatments.
[1] Fengjiao Zhang et al. DOI: 10.1038/ncomms9356
[2] Zia et al. DOI: 10.1002/adma.201505364
3:15 PM - NM3.17.03
Hydrophobically-Modified Nanoporous Silica Aerogel as a Bacteria Repelling Hygienic Material for Enhanced Healthcare
Jun Kyun Oh 1 , Luis Cisneros-Zevallos 1 , Mustafa Akbulut 1
1 , Texas A&M University, College Station, Texas, United States
Show AbstractHealthcare-associated infections (HAIs) caused by pathogenic bacteria are a worldwide problem and responsible for numerous cases of morbidity and mortality. Exogenous cross-contamination is one of the main mechanisms contributing to such infections. This work investigates the potential of hydrophobically-modified nanoporous silica aerogel as an antiadhesive hygienic material that can inhibit exogenous bacterial contamination. Nanoporous silica aerogels were synthesized via sol-gel polymerization of tetraethyl orthosilicate and hydrophobized using trimethylsilyl chloride. Bacterial adhesion characteristics were evaluated via dip-inoculation in suspensions of Gram-negative Escherichia coli O157:H7 and Gram-positive Staphylococcus aureus. The attachment of E. coli O157:H7 and S. aureus to “hydrophobic nanoporous silica aerogel” (HNSA) was found to be significantly lower than that to hydrophilic and hydrophobic nonporous silica materials: 99.91% (E. coli O157:H7) and 99.93% (S. aureus) reduction in comparison to hydrophilic nonporous silica, and 82.95% (E. coli O157:H7) and 84.90% (S. aureus) reduction in comparison to hydrophobic nonporous silica. Additional bacterial proliferation studies revealed that bacterial antiadhesion properties (i.e., not antibacterial effects) were responsible for the observed reductions. These results suggest that the use of HNSA as surfaces that come into contact with bacterial pathogens in the healthcare environment can improve bacterial hygiene, and therefore may reduce the rate of HAIs. Overall, bacterial antiadhesion properties as well as other distinctive properties such as superior thermal insulation and ultra-lightweight make hydrophobically-modified nanoporous silica aerogel an attractive candidate as a novel hygienic surface.
NM3.18: Son et Lumiere (Sound and Light)
Session Chairs
Stephanie Brock
Firouzeh Sabri
Friday PM, April 21, 2017
PCC West, 100 Level, Room 105 BC
4:00 PM - *NM3.18.01
Superior Sound Transmission Loss in Mechanically Strong and Ductile Aerogels
Sadeq Malakooti 1 , Gitogo Churu 2 , Alison Lee 1 , Qun Lu 3 , Fen Wang 3 , Tingge Xu 1 , Samuel May 1 , Suzie Ghidei 1 , Huiyang Luo 1 , Ning Xiang 4 , Chariklia Sotiriou Leventis 5 , Nicholas Leventis 5 , Hongbing Lu 1
1 Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, Texas, United States, 2 Department of Mechanical Engineering, LeTourneau University, Longview, Texas, United States, 3 , Nanjing Nashi New Materials, Inc., Nanjing, Jiangsu, China, 4 Department of Electrical, Computer, and Systems Engineering and School of Architecture, Rensselaer Polytechnic Institute, Troy, New York, United States, 5 Department of Chemistry, Missouri University of Science and Technology, Rolla, Missouri, United States
Show AbstractAerogels are porous nanostructured materials consisting of 3D networks of fractal nanoparticles. They are characterized by high porosity and high specific surface area, and they possess unique properties including low mass density, high specific strength, and low thermal conductivity. Recently, we found that ductile aerogels produced in our laboratories showed extremely high acoustic transmission loss: over 30 dB per cm of thickness with polyurea (PUA) aerogels at 0.25 g/cm3, 35 dB/cm with an X-aerogel, and over 50 dB with pDCPD at 0.1 g/cm3. Fundamental mechanisms behind the extraordinary acoustic attenuation in aerogels were investigated. Our aerogels share some striking similarities with acoustic metamaterials, in which numerous mechanisms have been introduced to provide band gaps for acoustic wave transmission. For example, in PUA at 0.25 g/cm3, 2 µm dense polyurea particles are connected with a nanofibrous polyurea web, forming a highly random and complex spring-mass system. At first glance, a conceptual multi-degree-of-freedom mass-spring-damper system was considered to study the wave propagation through the nanostructured aerogels. The model was conducted for both regularly and randomly distributed masses. The results indicated that when springs and masses are arranged in regular orders (evenly distributed), they will not induce any wave attenuation. However, when they are in random arrangement, significant wave attenuation is observed. Results are given for different configurations consistent with morphologies of the nano/microstructures observed for aerogels. In the next step toward modeling of such complex hierarchical and random structural material, the continuum Biot theory of poroelasticity was implemented to analyze the experimental sound transmission results. Biot’s theory is an efficient two-phase modeling, addressing wave speed, attenuation, dispersion and etc. Here the aerogel material is considered as an air-filled porous structure with comparable fluid and solid densities. At low frequency range, the Poiseuille fluid flow and having longer wavelength than the phonon mean free path of the aerogel are valid assumptions, which eventually lead us to consider a diffuse wave propagation field within the aerogel. Accordingly, the sound transmission loss of a single layer aerogel was calculated and compared with the stated experimental results. Comparing the theoretical results and the experimental observations build up a qualitative/quantitative framework on the understanding of the effects of the nanoparticle network dynamics and its interaction with air on the overall acoustic properties of aerogels. The results of this study might be helpful for the design of the other new hierarchical materials.
4:30 PM - NM3.18.02
First Steps towards Bio-Based Static True Volumetric 3D Displays—Transparent Cellulose Scaffolds Covalently Equipped with Photon Upconverting Rare Earth Metal Doped Nanophosphors (uc-NP)
Sakeena Quraishi 1 , Sven Plappert 1 , Thomas Rosenau 1 , Falk Liebner 1
1 , BOKU University Vienna, Vienna Austria
Show AbstractDoping of nanoparticles from transition metal compounds with rare-earth metal ions, such as Eu3+ affords nanophosphors which feature upconversion (anti-Stokes) photoluminescence (uc-NP). Homogeneous dispersion and chemical immobilization of uc-NP in a suitable transparent matrix allows to generate adressable «active elements» transparent in off state but either opaque or luminous in on state. Switching between these two states can be accomplished by pulsed IR laser light. The emission of photons from selectively activated ensembles of uc-NPs having different PL characteristics can be employed to create visual representations of any object in three physical
dimensions as opposed to planar images of traditional screens, thus providing ultimate physiological depth cues. As the color gamut of uc-NPs is typically much greater than that of the common RGB standard, 3D color images of high brilliance can be obtained provided that a well-balanced mixture of uc-NPs capable of emitting in the whole range of the visible light is randomly dispersed within the transparent matrix.
Following our previous works on transparent, monolithic aerogels from nematic liquid-crystalline, nanofibrillated carboxyl cellulose derivatives, their reinforcement by percolating networks of biocompatible polymers or post-scCO2-drying uniaxial densification and covalent equipment with both semiconductor and carbon based quantum dots, this paper communicates the results of an ongoing study investigating approaches towards grafting of uc-NP onto the large internal surface of transparent, highly porous yet mechanically robust aerogels from nematic liquid-crystalline suspensions of nanofibrillated oxidatively modified cellulose.
4:45 PM - NM3.18.03
Optically Transparent, Thermally Insulating Silica Aerogels for Solar-Thermal Receivers
Sungwoo Yang 1 , Bikram Bhatia 1 , Lin Zhao 1 , Elise Strobach 1 , Thomas Cooper 1 , Lee Weinstein 1 , Xiaopeng Huang 1 , Svetlana Boriskina 1 , Gang Chen 1 , Evelyn Wang 1
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractAerogels are well known for their thermally insulating properties due to their nano-porous structure and low solid volume fraction. In particular, optically transparent and thermally insulating monolithic silica aerogels can significantly improve the efficiency of solar absorbers by acting as a spectral selective cover. It allows solar radiation to transmit through but minimizes the absorber losses in the infrared spectrum. In addition, heat losses due to solid and gas conduction can also diminished due to the high porosity (>90%) and pore sizes smaller than the mean free path of gas molecules which obviates the need for operation in vacuum. However, the transparency of silica aerogels in the solar spectrum is typically <85%, which has prevented its adoption in solar-thermal applications. Here, we present optical and thermal characterization of highly transparent silica aerogels optimized for solar-thermal applications. A solar-weighted transmittance was 96% for an 8 mm sample thickness, which exceeds that of glass. Minimizing the size of scattering centers (particle and pores) was the key to minimize the scattering losses at low wavelengths. In addition, the aerogel thermal properties were characterized using a custom-built cooler bridge setup based on the steady state method. The measured heat transfer coefficient for a temperature difference between 400 C and 250 C was 6 W/m2K for an 8 mm thick sample. The thermal measurements showed excellent agreement with a detailed numerical model based on the spectral equation of radiative transfer that uses the measured extinction coefficient as an input. Consequently, a lab-scale demonstration showed that the effective solar absorption/thermal emissivity of an aerogel covered black paint was 0.93/0.2 at 400 C, which makes it comparable to the state-of-art selective surfaces. Transparent aerogel achieved ~250 C under 1- sun and ambient conditions. Furthermore, optical and thermal efficiency of an outdoor 3 kW prototype system under real on-sun will be discussed. This work shows the promise of simultaneously achieving high transparency and low heat transfer coefficients in silica aerogels, which can significantly improve the energy conversion efficiency of various solar-thermal systems.
This work is supported by the U.S. Department of Energy through the Advanced Research Projects Agency−Energy (ARPA-E) FOCUS program under Award No. DE-AR0000471.
5:00 PM - NM3.18.04
Optical Switching of Silica-Aerogels upon Gas Sorption
Christian Scherdel 1 , Gudrun Reichenauer 1 , Michael Boehm 1
1 , Bavarian Center for Applied Energy Research, Wuerzburg Germany
Show AbstractUpon mesopore filling (adsorption) and emptying (desorption) certain silica aerogels and xerogels have been found to turn from highly transparent to strongly opaque [1-3]. This effect can be observed upon capillary condensation of any gas or vapour; the sample becomes transparent when all pores are either completely filled or emptied. Experimental analysis reveals that this behavior is fully reversible and the opacity is more pronounced upon desorption compared to adsorption.
To investigate the switching effect, we prepared several silica xerogels (highly transparent thin slices) using different synthesis parameters and analyzed the change in optical properties (visible transmission as a function of wavelength) in-situ during ad- and desorption of ethanol and water, respectively.
Complementary in-situ small angle neutron scattering data were recorded during ad- and desorption of ethanol in one of the samples. The experiment was designed in such a way that the adsorbed phase had the same scattering length density as the silica skeleton. Upon desorption the condensed phase is found to form entities with a characteristic extension of more than 100 nm thus clearly exceeding the average pore size (< 10 nm) of the xerogel under investigation while during adsorption the scattering entities are smaller – more likely in the order of the aerogel’s pore size.
[1] Reichenauer G, Fricke J, Manara J, Henkel J. J. Non-Cryst. Solids. 2004;350:364-71
[2] Reichenauer G, Manara J, Weinlaeder H. Stud. Surf. Sci. Catal. 2007;160:25-32
[3] Wong APY, Kim SB, Goldburg WI, Chan MHW. Phys. Rev. Lett. 1993;70(7):954-957
5:15 PM - NM3.18.05
Understanding the Wave-Subwavelength Structure Coupling in the Aerogels
Ai Du 1 , Wei Sun 1 , Shangming Huang 1 , Weiwei Xu 1 , Yu Feng 1 , Jun Shen 1 , Bin Zhou 1
1 , Tongji University, Shanghai China
Show Abstract
Owing to its diverse chemical compositions and unique properties which could fill the gap between condensed- and gas-state matter, aerogels could be regarded as a new state of matter. Much work discussed the influence of density on the physical properties, but rare work talks clearly about the microstructure/properties relationship. In this talk, we will introduce some new results about the subwavelength microstructure-induced acoustical or optical response occurring in the aerogels.
Acoustical response: we found that the sound velocities of Cu-based aerogels with different skeleton structure (nano-, micro- or nano/micro-structured) are very low, among which the latter structured aerogel exhibits the lowest longitudinal wave velocity (<80 m.s-1). The heavy-core & soft-shell primary structure and the concentration of the core are the key parameters determining the sound velocity besides the density. Localized resonance effects are found when the sound wave propagated in the micro/nano-aerogels, whose lowest phonon band gap located in ~ 500 Hz. The inhomogeneous microstructure similar to the multi-mode spring oscillator can resonate with the acoustical wave in specific frequencies obviously increasing the coupling between aerogels and acoustical wave. In other frequencies, forced oscillation between the oscillator and wave occurs localized, neglecting the diffraction scale, which can reduce the wavelength thus reducing the wave velocity.
Optical response: we found that subwavelength microstructure obviously affect the diffuse back-reflectivity of the carbon aerogels. These were prepared with different nanostructure by carbonizing the resorcinol-formaldehyde (RF) aerogels and showed ultralow reflectivity in the UV-Vis-NIR spectra. Modifying concentration (W%) and catalyst ratios (R/C) of the RF colloid, leads to a roughly positive correlation between reflectivity and density. Moreover, R/C parameter which determined the microstructure of the aerogels affected significantly the reflectivity. By tuning their nanostructure, we got the minimum at about 0.19 % which approached the measuring limit of our equipment. Carbon aerogels were activated using CO2 at 1000oC to induce the micropore (< 2 nm). The reflectivity of carbon aerogels decreased sharply after activating, indicating that the structure much smaller than the wavelength (< 2 nm) could affect the light propagation greatly. We attribute this behavior to the indirect interactions including electromagnetic-electron interaction and electron-microstructure interaction. The subwavelength structure of the conductor strongly decreases the mean free path of the electrons inside, leading to an extra absorption besides considering the Joule’s heating.
5:30 PM - NM3.18.06
Preparation and Properties of Transparent Polymethylsiloxane Aerogels with Ethenylene-Bridging Moiety
Taiyo Shimizu 1 , Kazuyoshi Kanamori 1 , Kazuki Nakanishi 1
1 , Kyoto University, Kyoto Japan
Show AbstractINTRODUCTION
In recent research on aerogels, organic-inorganic hybridization has widely been explored in order to obtain mechanically strong or flexible aerogels. Among those, aerogels prepared solely from organoalkoxysilane as a precursor display substantial potential for realizing mechanically strong aerogels with visible-light transparency. By precise control of pore structure using an acid-base 2-step sol-gel reaction and surfactant, transparent polymethylsilsesquioxane (PMSQ) and ethylene-bridged polymethylsiloxane (Ethy-BPMS) have been obtained in our recent works. The obtained aerogels show significant strength and flexibility against compression (for PMSQ) and compression and bending (Ethy-BPMS), respectively.
In the present study, a preparation of aerogels from 1,2-bis(methyldiethoxysilyl)ethene has been investigated. This precursor forms a ethenylene-bridged polymethylsiloxane (Ethe-BPMS) network if the sol-gel reactions ideally proceed. By using a strong acid catalyst for hydrolysis and strong base for polycondensation in a surfactant-based solution, transparent Ethe-BPMS aerogels have successfully been obtained. Obtained aerogels were evaluated in terms of transparency, microstructure, mechanical properties, and so forth. Comparison of mechanical properties to those of PMSQ and Ethy-BPMS aerogels was also carried out.
EXPERIMENTAL SECTION
The precursor 1,2-bis(methyldiethoxysilyl)ethene and surfactant polyoxyethylene 2-ethylhexyl ether were first mixed together and 5 mM nitric acid was added to the mixture. After 10 min stirring, aqueous tetramethylammonium hydroxide (TMAOH) was added to the mixture and stirred for 30 s. The reaction solution was then gelled in an oven at 80 °C, followed by aging for 4 d. The obtained gel was washed with methanol and 2-propanol, and then dried with supercritical CO2 to obtain an aerogel.
RESULTS AND DISCUSSION
Visible-light transparency of the obtained Ethe-BPMS aerogels varied with the concentration of aqueous TMAOH used, and highly transparent (87 % at wavelength of 550 nm, corresponding to a 10 mm-thick sample) aerogels have been obtained with an optimized synthetic condition. In terms of the deformation behavior during uniaxial compression, gelation and aging temperature strongly affects the degree of resilience (volume recovery after unloaded), and the aerogel gelled at 80 °C shows superior resilience after 50 % compression. Comparison of mechanical properties to the aerogels with similar molecular networks revealed that the stress relaxation behavior of transparent Ethe-BPMS aerogels during the constant compression at 50 % is much smaller than that of Ethy-BPMS, even though the preparation conditions of both aerogels are mostly identical. This result is presumably originated from the difference in rigidity of the organic linkages.
NM3.19: Art
Session Chairs
Stephanie Brock
Stephen Steiner
Friday PM, April 21, 2017
PCC West, 100 Level, Room 105 BC
5:45 PM - NM3.19.01
Spirited Skies Project—Silica Aerogel in Art and Design Applications
Ioannis Michaloudis 1
1 , Charles Darwin University, The Gardens, New South Wales, Australia
Show AbstractThis interdisciplinary practice aims to improve public perception of scientific research, and to facilitate informed decision making regarding climate change and how it affects everyday life. It also hopes to break down (or bridge?) the isolated silos of Art and Science, by emphasising the role of imagination as a tool of creation and innovation in the new economies of the 21st Century. Notwithstanding the ephemeral appearance of the super-light silica aerogel used by Michaloudis in his sculptures, the longevity of some of his art seems guaranteed. Two works, Bottled Nymph and Noli Me Tangere have been selected to be rocketed to the moon as part of the MoonArk sculpture. The sculptures will be aboard a Space X Falcon 9 rocket launched in late 2017 from Cape Kennedy in an Astrobotic Robotic Lunar Mission, and will remain on the moon, potentially, for billions of years. Spirited Skies is a project where we experience by touching other forms of longevity of the ephemeral silica aerogel. Here we have double jacketed borosilicate glass vials filled with Michalous' skies and clouds in a unique way transforming everyday's life trivial objects to awesome artworks. The World' premiere presentation of this project will be exhibited in this MRS Conference.