Kazumi Kato, National Institute of Adv. Ind. Sci. Tech. (AIST)
Sanjay Mathur, University of Cologne
Xavier Obradors, ICMAB - CSIC
Piyush Shukla, Honeywell
RR2: Inorganic/Organic Hybrid, Porous Monolith and Films II
Tuesday PM, April 07, 2015
Marriott Marquis, Golden Gate Level, C2
2:30 AM - *RR2.01
Broad-Band/Omnidirectional, Nanostructured Graded-Refractive-Index, Antireflective Coatings with Self-Cleaning/Anti-Fogging Capability
Tolga Aytug 1 Liu Tao 1 Andy R Lupini 1 Ilia Ivanov 1 G. E. Jellison 1 Pooran C. Joshi 1 David K. Christen 1 Mariappan P. Paranthaman 1 Rajesh Menon 2 Peng Weng 2
1Oak Ridge National Laboratory Oak Ridge United States2The University of Utah Salt Lake City United StatesShow Abstract
Traditional superhydrophobic coatings are soft in nature, with a Teflon-like surface chemistry, which results in reduced adhesion and durability. By combining vapor phase deposition together with wet chemical processes to produce differentially-etched, nanostructured glass materials, we have overcome many of these common problems. Here we describe the formation of atomically bonded, optical-quality, nano-textured porous thin glass film coatings on glass plates, utilizing metastable spinodal phase separation in a low-alkali borosilicate glass system. As formed, these coatings are structurally superhydrophilic (i.e., display anti-fogging functionality) and demonstrate robust mechanical properties. After appropriate chemical surface modification, they exhibit exceptional superhydrophobic performance, hence self-cleaning properties, with water droplet contact angles reaching to 172o. Moreover, these nanostructured surfaces can be engineered to provide graded index anti-reflectivity with broadband and omnidirectional transparency. In particular, when applied to solar cover panels, we show that these coatings couple more light into the photovoltaic cells and substantially reduce the light energy lost to reflection, yielding an increased power output of the photovoltaic modules ~3-5% while preventing dust/pollution accumulation.
3:00 AM - RR2.02
Surface Modification with Polyhedral Oligomeric Silsesquioxanes Silanols
Luis Edgar Cabrales 1 Karla Calderon 1 Irvin Hinojosa 1 Felipe Valencia 1
1California State University Bakersfield Bakersfield United StatesShow Abstract
Interest in surface engineering has been increasing in recent years. There are several methods which can be used to modify the properties of surfaces. Some of these techniques include sol-gel method, plasma, chemical vapor deposition, atomic layer deposition, and also traditional wet chemistry methods. Some novel materials for surface modification are Polyhedral oligomeric silsesquioxanes (POSS) silanols. These materials possess some of the surface modification characteristics of other silicon-based materials. The POSS silanols were deposited by immersion methods on glass surfaces. Several concentrations and curing temperatures were evaluated. Contact angle measurements of water and other liquids were used to calculate the surface energy. Dynamic capture mode was used to calculate the hysteresis of advancing and receding contact angles. The hysteresis provided information regarding the wettability properties of the obtained surfaces. The results showed that POSS silanols were capable of impart hydrophobicity to surfaces at low concentration in solutions. The unique properties of POSS silanols for surface modification are also discussed and surface modification properties of these novel materials were also explored in the textile area.
3:15 AM - RR2.03
Aqueous Laser Ablation Synthesis of Hybrid Copper-Chitosan Nanoantimicrobials for Applications in Food Packaging and Bio-Risk Containment
Maria Chiara Sportelli 1 Antonio Ancona 2 Rosaria Anna Picca 1 Annalisa Volpe 2 3 Adriana Trapani 4 Giuseppe Trapani 4 Nicola Cioffi 1
1Department of Chemistry, University of Bari "Aldo Moro", Bari Italy2IFN-CNR, Physics Department ldquo;M. Merlinrdquo; Bari Italy3Department of Physics, University of Bari "Aldo Moro" Bari Italy4Pharmaco-Chemistry Department, Universitagrave; degli Studi di Bari ldquo;Aldo Morordquo; Bari ItalyShow Abstract
Copper-chitosan (Cu-CS) nanoantimicrobials are a novel class of bioactive nanosized agents, providing enhanced/synergistic efficiency in the prevention of biocontamination in several application fields, ranging from food packaging to the prevention of nosocomial infections . Designing bioactive materials, with controlled metal ion release, exerting significant bioactivity and associated low toxicity for humans, is nowadays one of the most important challenges for the scientific community . In this work, we propose a new material combining the well-known antimicrobial properties of CuNPs  with those of bioactive CS, a cheap natural polymer widely exploited for its biodegradability and nontoxicity . Here we exploited ultrafast femtosecond laser pulses to disgregate, via laser ablation, a Cu solid target immersed into aqueous CS solutions . Homogeneously dispersed Cu-CS colloids were obtained by tuning the Cu/CS molar ratios, according to the initial chitosan concentration, as well as other experimental parameters. Cu-CS colloids were characterized by several techniques. UV-Vis and Fourier Transform Infra-Red (FTIR) spectra were used to study copper complexation with the organic matrix. X-ray Photoelectron Spectroscopy (XPS) allowed us to assess copper surface chemical speciation, by the accurate curve fitting of both photoelectronic Cu2p3/2 and Auger CuLMM high-resolution regions. Transmission Electron Microscopy (TEM) was used to morphologically characterize the novel nanocomposites. We also obtained well-dispersed nanocomposite thin films by spin coating these hybrid nanocolloids on several substrates. The effectiveness of the proposed nanocoatings as novel antimicrobial agents was demonstrated in bioactivity experiments performed on several target microorganisms.
 N. Cioffi, M. Rai Eds., “Nano-antimicrobials. Progress and Prospects”, Springer-Verlag Publisher, 1st Edition, ISBN 978-3-642-24427-8 (2012).
 N. Cioffi et al., Chem. Mater., 17, 2005, 5255.
 M. Kong, et al., Int. J. of Food Microbiol., 144, 2010, 51.
 A. Ancona et al., Mat. Lett., 136, 2014, 397.
3:30 AM - RR2.04
Metal-Organic Framework Coatings on Polymer Surfaces Accessed through the Dissolution-Precipitation of Metal Oxide Nanocrystal Precursors
Stephen M. Meckler 2 1 Changyi Li 3 1 Wendy L. Queen 1 David Prendergast 1 Jeffrey R. Long 2 5 Delia J. Milliron 4 Brett A. Helms 1
1Lawrence Berkeley National Laboratory Berkeley United States2University of California, Berkeley Berkeley United States3University of California, Berkeley Berkeley United States4The University of Texas at Austin Austin United States5Lawrence Berkeley National Laboratory Berkeley United StatesShow Abstract
Incorporating metal-organic frameworks (MOFs) in polymeric structures is an important step in applying these porous crystals to industrial scale gas separation applications. Nanoscale MOF coatings on polymer membranes can promote selective transport and act as molecular sieves, but facile and scalable syntheses for these coatings are still in development. Here, a method to synthesize sub-micron MOF coatings from metal oxide nanocrystal precursors on porous polymer thin films is demonstrated. The coatings&’ morphologies and grain sizes were controlled through changes to the reaction conditions. Grazing incidence x-ray diffraction was used to confirm the presence of crystalline MOF in the thin films. These bilayer structures are promising as next-generation gas separation membranes.
3:45 AM - RR2.05
Graded Porous Inorganic Materials Derived from Self-Assembled Block Copolymer Templates
Yibei Gu 1 Joerg Werner 1 Rachel Dorin 1 Spencer Robbins 1 Ulrich Wiesner 1
1Cornell University Ithaca United StatesShow Abstract
Graded porous inorganic materials directed by macromolecular self-assembly are expected to offer unique structural platforms relative to conventional porous inorganic materials. Their preparation to date remains a challenge, however, based on the sparsity of viable synthetic self-assembly pathways to control structural asymmetry. Here we demonstrate the fabrication of graded porous carbon, metal, and metal oxide film structures from self-assembled block copolymer templates by using various backfilling techniques in combination with thermal treatments for template removal and chemical transformations. The asymmetric inorganic structures display mesopores in the film top layers and a gradual pore size increase along the film normal in the macroporous sponge-like support structure. Substructure walls between macropores are themselves mesoporous, constituting a structural hierarchy in addition to the pore gradation. Final graded structures can be tailored by tuning casting conditions of self-assembled templates as well as the backfilling processes. We expect that these graded porous inorganic materials may find use in applications including separation, catalysis, biomedical implants, and energy conversion and storage.
4:30 AM - RR2.06
Engineering Novel Metal-Organic Framework Materials through Modular Hydrothermal Approach for Clean Energy Applications
Zhigang Hu 1 Dan Zhao 1
1National University of Singapore Singapore SingaporeShow Abstract
The fast civilization accompanying huge dependence on the fossil fuels consumption has never aroused such world-wide concern of energy depletion together with devastating consequences for the global economy and quality of human life. Carbon dioxide emission, as a result of burning fossil fuels for energy, has also raised an ever-increasing attention because of its greenhouse effect that could incur global warming and human nutrition deficiency. Although researchers nowadays are aiming at developing new technologies to physically capture CO2 and chemically utilize CO2 as a raw material in the production of commercially important chemicals, it is still a temporary solution since how to dispose large amount of captured CO2 in an effective fashion remains the big challenge. In the long term, developing new and sustainable energy resources, such as solar energy and biomass, will play the major role. Metal-organic frameworks (MOFs), as a new class of crystalline inorganic-organic hybrid materials composed of inorganic metal nodes and organic linkers, have recently emerged as an ideal platform for engineering novel functional porous materials for clean energy applications because of possessing a diversity of coordinated models of metal ions and functional organic linkers, high porosity and rich pore functionalities. In this work, we aim to engineer one of the most promising MOF, UiO-66(Zr), through modular hydrothermal synthesis as advanced adsorbents for CO2 capture and highly efficient heterogeneous catalysts for biomass conversion. We have chosen two model ligand, 2, 5-dicarboxylic-1, 4-benzenedicarboxylic acid (DCBDC) and sodium 2-sulfoterephthalate (SSBDC), to synthesize isostructural UiO-66 MOFs with different chemical functionalities (UiO-66-(COOH)2 and UiO-66-SO3H) via both traditional hydrothermal and modular hydrothermal reactions. Powder X-ray diffraction (PXRD), field-emission scanning electron microscope (FE-SEM) and gas sorption isotherms were applied to characterize the phase purity, morphology and gas adsorption properties, respectively. Compared to traditional hydrothermal synthesis, our modular synthesis has successfully lead to microporous UiO-66-(COOH)2 with much higher BET surface area (~500 m2/g) and more than doubled CO2 uptake (8% w/w) as well as mesoporous UiO-66-SO3H with higher BET surface area (~420 m2/g) and highly efficient catalytic activity toward fructose conversion (>99%) to 5-hydroxymethylfurfural (5-HMF, ~80% yield). Our highly tuned modular hydrothermal synthesis method has provided a paradigm to synthesize novel functional porous materials for clean energy applications.
4:45 AM - RR2.07
Electrochemical Plating of Mesoporous Metals Directed from Micelle Assemblies
Cuiling Li 1 Yusuke Yamauchi 1
1National Institute for Materials Science (NIMS) Tsukuba JapanShow Abstract
Mesoporous structures can steadily provide many functional sites, which are critical for solving emergent problems. Especially, metallic mesoporous materials can exhibit rather high carrier density and thus remarkable optical response and catalytic performance, which are not attainable by using other compositions of mesoporous materials (e.g., silica- and carbon-based compositions), and even other nanostructed metals. The rational design of mesoporous metals with tunable pore size toward practical applications is a most attractive and challenging objective. Although many well-developed approaches have been investigated in the fabrication of mesoporous silica, carbon, and other transition metal oxides, few of them are competent in obtaining mesoporous noble metals.Fortunately, we recently have succeeded in obtaining mesoporous metals, i.e., Pt, Pd, and Pt-based alloys, by using micelle assembly of non-ionic surfactants (or block copolymers). This work provides an exclusive facile and efficient strategy in obtaining mesoporous metals. Further, we extended the effective way to prepare mesoporous Au films, which have been proved to be fairly difficult by using the soft-templating method, by utilizing spherical micelles of polystyrene-block-poly(oxyethylene) (PS-b-PEO) diblock copolymers as soft-templates for the first time. The pore sizes of the obtained Au films could be well controlled in a wide range, and the various pore sizes surely brought tunable surface-enhanced Raman scattering (SERS) for molecule detection due to multiple ‘hot spots&’ built up in the mesopores as well as in the vicinity of narrow walls between the pores.
5:00 AM - RR2.08
Robust Hierarchically Porous Zirconium Phosphate Monolith: Synthesis, Ion Adsorption and Catalysis
Yang Zhu 1 Kazuki Nakanishi 1 Kazuyoshi Kanamori 1
1Kyoto Univ Kyoto JapanShow Abstract
In the modern strategy of designing and synthesizing novel materials, versatility is one of the key concepts pursued with high priority. The design concept includes the development of clean, facile and sustainable methods as well as simultaneous controls over the structural and chemical properties for various applications. Zirconium phosphate (ZrP) has been focused as a multifunctional versatile material for different applications. Since its first report on synthesis in the laboratory scale and the ion exchange behavior by Clearfield and co-workers, ZrP has been attracting a great deal of interest due to its extended applications in various possible utilizations such as catalyst and catalyst support for different chemical reactions, proton conductor for fuel cells, and ion exchanger for water purification.In order to fulfill the requirements for applications in different fields, ZrP has been prepared into various forms such as micro/nanoparticles and thin films.Traditional synthetic routes, however, find their limitations in designing a mechanically stable monolithic shape combining hierarchical porosity in ZrP materials. Well-controlled hierarchically porous structures are advantageous for its applications as adsorbent, catalyst and catalyst support due to better accessibility of reactants to active sites and ease for recycle and reuse.
We herein present a low-temperature, one-step liquid phase synthesis of hierarchically porous ZrP monoliths with tunable compositions (from Zr(HPO4)2 (Zr:P = 1:2) to NASICON (Na super ionic conductor)-type ZrP (Zr:P = 1:1.5)) as well as macropore size (from 0.5 to 5 µm). The hierarchically porous structure has been obtained as a result of polymerization-induced phase separation (spinodal decomposition) during the sol-gel transition. Co-continuous macroporous structure is stable against heat treatment, which yields pure ZrP2O7 phase at 1000 °C, while treatment at even higher temperature (1400 °C) leads to further transformation.The as-synthesized ZrP monolith with high reactive surface area (600 m2 gminus;1) and relatively high mechanical strength (Young&’s modulus 320 MPa) has been applied to ion adsorption and catalysis. A simple syringe device inserted tightly with the ZrP monolith as a continuous flow setup has been demonstrated to remove various toxic metal ions in aqueous solution, which shows promising results for water purification. Meanwhile, ZrP monolith as an acidic heterogeneous catalyst also provides a platform for the catalytic dehydration of xylose, and high selectivity toward furfural production has been confirmed in water as the “green” solvent.
The synthetic method we have developed here would be further applied to the synthesis of other metal phosphates with hierarchically porous structure. The hierarchically porous ZrP and derivative monoliths may find high potentials in more sustainable applications such as enrichment and recycling of precious metals and fuel cells.
5:15 AM - RR2.09
Synergy of Static Magnetic Field Stimulation and Magnetisation towards Bactericidal Property of Multifunctional HA-Fe3O4 Biocomposites
Indu Bajpai 2 Kantesh Balani 2 Bikramjit Basu 1
1Materials Research Centre, Indian Institute of Science Bangalore India2Indian Institute of Technology Kanpur Kanpur IndiaShow Abstract
In addressing the issue of prosthetic infection, the present work demonstrates the synergistic effect of the application of static magnetic field (SMF) and utilizing magnetic properties of substrate on affecting the bactericidal property in vitro. For this purpose, HA-xFe3O4 (x: 10, 20 and 40 wt.%) powder compositions were sintered using uniquely designed spark plasma sintering conditions (three stage sintering with final holding temperature of 1050 °C for 5 mins). During bacteria culture experiments, 100 mT SMF is applied to growth medium (with immersed on HA-xFe3O4 substrate) for 30, 120 and 240 min. A combination of MTT assay, membrane rupture assays, live/dead assay and fluorescence microscopic analysis showed that the bactericidal effect of SMF increases with the exposure duration as well as increasing content of Fe3O4. Importantly, the synergistic bactericidal effect is found to be independent of bacterial cell type, as similar qualitative trend is measured with both gram negative (E.coli) and gram positive (S.aureus) strains. The reduction in E.coli viability is 83% higher on HA-40 wt%Fe3O4 composite after 4 hrs exposure to SMF as compared to non-exposed control. Importantly, all the HA-Fe3O4 composites demonstrated bactericidal property by rupturing the membrane of E. coli bacteria, while supporting cell growth of metabolically active human fetal osteoblast cells over 8 days culture. A systematic decrease in bacterial viability with Fe3O4 addition is consistent with a commensurate increase in reactive oxygen species (ROS). Overall, the present study illustrates significant role being played by magnetic substrate compositions towards bactericidal property than by magnetic field exposure alone.
5:30 AM - RR2.10
Self-Assembled Nanoparticle / PS-b-PEO Block Copolymer Hybrids and their Application as Dielectric Layers in OTFMTs
Johannes Kirschner 1 Luis F Portilla 1 Marcus Halik 1
1Institute of Polymer Materials, University Erlangen-Nuuml;rnberg Erlangen GermanyShow Abstract
Block copolymers (BC) represent a multifunctional tool for hierarchical structure fabrication down to the nanoscale. Due to the incompatibility of the homopolymer blocks, thin films of BCs can phase separate to form diverse periodic structures like spheres, cylinders or lamellae. It has been shown that by carefully matching the surface functionalization of nanoparticles to the polymer subunits in BCs, well-ordered hybrid materials can be achieved in which nanoparticles are selectively enriched in one of the BC phases. 
We provide metal oxide nanoparticles with different shell functionalities based on molecules with phosphonic acid anchor groups.  With this approach we are able to seamlessly fine-tune the surface properties of the nanoparticles from ultra-hydrophobic to extremely hydrophilic. This enables us to selectively target one or both of the BC phases. In our experiments, ambipolar polystyrene-b-polyethylene glycol diblock copolymers (PS-b-PEO) with high Flory-Huggins interaction parameter serve as organic matrix. We examine the phase-separation behavior of the BC films as a function of the nanoparticle surface energy, their size and the amount of particles in the polymer layer. The applied methods include electron microscopy and scanning probe microscopy as well as electrical characterization.
The nanoparticle/ PS-b-PEO hybrids are applied as dielectric layers in organic transistors, where they simultaneously serve as non-volatile charge storing layer to yield organic thin-film memory transistors (OTFMTs). Phase boundaries created by the BC lead to spatial separation of the embedded nanoparticles, which enhances charge storing performance. The hybrid dielectrics exhibit increased relative permittivity without compromised insulating properties.
 H. Zhang, Y. Liu, D. Yao, B. Yang, Chem. Soc. Rev.2012, 41, 6066.
 L. Portilla, M. Halik, ACS Appl. Mater. Interfaces2014, 6, 5977.
RR3: Poster Session: Inorganic/Organic Hybrid, Porous Materials and Functional Thin Films
Tuesday PM, April 07, 2015
Marriott Marquis, Yerba Buena Level, Salon 7/8/9
9:00 AM - RR3.01
Properties of Transparent Silsesquioxane Aerogels with Reactive Side Groups
Taiyo Shimizu 1 Kazuyoshi Kanamori 1 Kazuki Nakanishi 1
1Graduate School of Science, Kyoto University Kyoto JapanShow Abstract
Due to the increase of world energy consumption, energy-saving technology has been attracting a lot of attention of scientists. Silica aerogels, which can be obtained by drying wet gels using supercritical drying methods, are candidate materials for high performance thermal-insulating window, because of their low thermal conductivity and high light transmittance. However, the practical use of aerogels is highly restricted by their low mechanical properties. In order to improve their mechanical properties, various kinds of organic-inorganic hybridization have been studied so far. Our group has reported the synthesis of aerogels composed of methylsilsesquioxane (MSQ, CH3SiO1.5), which show higher elastic behavior on compression, as well as high light transparency and low thermal conductivity comparable to those of silica aerogels. With silsesquioxane (RSiO1.5) materials, there is a possibility of obtaining transparent aerogels possessing a new property.
The aim of this work is to investigate the properties of silsesquioxane aerogels with substituent groups other than methyl. Since reactive substituent groups such as vinyl can be chemically modified even after the gelation, tuning of the properties of aerogels with these groups are available. Thus, we mainly focused on vinylsilsesquioxane (VSQ, CH2=CHSiO1.5) aerogels in this report. Although any other silsesquioxane aerogels, except for MSQ, have not been reported so far, we successfully obtained VSQ aerogels by utilizing acid-base 2-step reaction in surfactant-based solution. Obtained aerogels were evaluated in terms of their structural, optical and mechanical properties and availability of post treatment (e.g. radical reaction, thiol-ene reaction, etc.).
In the VSQ system, dilute nitric acid was added into vinyltrimethoxysilane (VTMS) and the mixed solution was stirred for hydrolysis. After a few minutes, a liquid surfactant was added into the solution, and then a strong base solution was added for polycondensation. The reaction solution was subsequently transferred into an incubator and gelled at given temperature. Obtained wet gels were aged for a few days and washed with alcohols, followed by supercritical drying.
With optimized starting composition, the VSQ aerogels were obtained in a transparent monolithic form. The VSQ aerogels showed flexible behavior on uniaxial compression; however, resilience after the removal of applied load was smaller than that of MSQ aerogels. Post treatment on wet VSQ gels was effective to improve their mechanical properties and highly flexible aerogels against compression were obtained without losing their transparency.
9:00 AM - RR3.02
Synthesis of Macroporous Hydridosilica Monoliths with Periodic Mesopores
Takahiro Nakanishi 1 Kazuyoshi Kanamori 1 Nirmalya Moitra 1 Nakanishi Kazuki 1
1Kyoto University Kyoto JapanShow Abstract
The syntheses of porous materials with controlled structure, porosity, surface functional groups and morphology can bring the materials into a myriad of unique properties and possible applications.
We have recently reported a synthesis of a unique type of macroporous hydrogen silsesquioxane (HSiO1.5, denoted as HSQ) monolith, which possesses reductive hydrosilyl groups on the pore surface. The HSQ materials are synthesized via the sol-gel process accompanied by phase separation, which is a reliable technique to tailor well-defined macropores in the material. The resulting HSQ monoliths were used both as a reductant and host to produce monolith-supported Ag, Au, Pt, Pd, Ru and their alloy nanoparticles by simultaneous reduction of these metal ions and embedment. In a different example, because of the hydrosilyl groups on the pore surfaces, the HSQ monoliths were successfully used as highly efficient, selective, fast, metal-free catalytic grafting of alcohols to develop a new alternate process of surface modification of silica.
It is interesting to impact the HSQ monoliths with periodic mesopores, because those materials would show high specific surface area, high mesopore volume and uniform-sized mesopores, leading to the ideal materials for catalysis, sensors, and biomedical applications. While many types of periodic mesoporous silica materials such as MCM41 and SBA-15 have long been studied, there have been only a few periodic mesoporous HSQ materials reported so far. This is because the three-dimensional (3-D) network of the HSQ materials is not robust enough, as their precursors have only three linkers. We herein we report our attempt in a synthesis of the first example of macroporous HSQ monoliths with ordered periodic mesopores.
The synthesis of the periodic mesoporous HSQ monoliths was conducted by combination of the sol-gel process and supramolecular templating method. We used triethoxysilane (HTES) and tetraethoxysilane (TEOS) for strengthening the siloxane frameworks. In a typical experiment, polymeric surfactant such as F127 and Brij78 was dissolved into HCl solution. After complete dissolution of the surfactant, the mixture was kept stirring for several minutes in an ice bath. Then TEOS was then added under vigorous stirring at 0 °C. After a clear solution was obtained, HTES was added under vigorous stirring at 0 °C until a clear solution was obtained. #12288;After these processes, the solution was kept at room temperature (RT) until gelation, followed by aging at RT for 1 day. The wet gels thus obtained were subjected to solvent extraction using acetone. The washed gels were finally dried at 40 °C for 12 h. The porous and molecular-level structures of the obtained dried gels were investigated by scanning electron microscopye, Fourier transform infrared spectroscopy and N2 adsorption-desorption.
9:00 AM - RR3.03
Synthesis of Hierarchically Macro/Mesoporous Titanium Phosphate Monolithic Gel
Koji Yoneda 1 Yang Zhu 1 Kazuyoshi Kanamori 1 Nakanishi Kazuki 1
1Kyoto University Kyoto JapanShow Abstract
Titanium phosphate is studied for extended applications, for example ion exchanger, adsorbent, fuel cell cathode, and solid acid catalyst. Hierarchically porous gels of several metal phosphate compositions, such as aluminum phosphate, zirconium phosphate, and calcium phosphate, have been synthesized via the sol-gel process accompanied by phase separation using metal salt and phosphoric acid as the precursors. In this work, hierarchically macro/mesoporous titanium phosphate monoliths have been synthesized from titanium(IV) oxysulfate (TiOSO4) and phosphoric acid as the precursors with poly(ethylene oxide) (PEO) and polyvinylpyrrolidone (PVP) as phase separation inducers in the solvent system of water, glycerol and dimethyl sulfoxide (DMSO).
In a typical experiment, titanium oxysulfate, PEO (Mw = 100,000), and PVP (Mw = 55,000) are dissolved in the mixed solvent of water, glycerol, and DMSO. Concentrated phosphoric acid is then added to that solution in an ice bath, after two solutions are cooled. The solution is kept 0 °C about 2 minutes until gelation. The obtained gel is then aged for 1 day at room temperature. The wet gels are solvent-exchanged with several solvents, such as 2-prapanol, methanol, and water. Some of the xerogels are calcined at the temperature of 300 °C to 1000 °C. Other wet gels are solvothermally treated at the temperature of 100 °C to 200 °C with ethylene glycol as the solvent, after the gels are solvent-exchanged with ethylene glycol. The macropore structure of the xerogels and heat-treated gels is observed by SEM. The BJH pore size distribution and the BET specific surface area are evaluated by nitrogen adsorption-desorption analysis. The crystal structures are analyzed by XRD.
We obtained co-continuous macroporous xerogels by employing proper amounts of PEO and PVP. The phase separation tendency, which determines the macropore size, can be changed by the amount of PEO. The increase of PEO amount causes an increase in porosity. The macropore size can also be controlled by the amount of PVP; the macropore size becomes larger as the PVP amount increases. The XRD patterns of as-dried xerogels show no sharp peaks, indicating amorphous structure. The XRD patterns of the gels calcined below 600 °C also do not show sharp peaks. The XRD patterns of the gels calcined over 800 °C exhibit sharp peaks attributed to titanium pyrophosphate (TiP2O7). The patterns of the solvothermally treated gels cannot be attributed to either titanium phosphate or titanium pyrophosphate. The BET specific surface area becomes the highest, 260 m2 gminus;1, in the as-dried xerogels prepared with a large amount of PVP and solvent-exchanged with 2-propanol. The modal mesopore size is about 30 nm. If calcined over 800 °C, the BET specific surface area is lowered to 4 m2 gminus;1. The BET specific surface area of the solvothermally treated gels becomes lower with increasing temperature, because the pore size grows larger at high temperature.
9:00 AM - RR3.04
Template Guided Self-Assembly: Influence of Lithographic Patterning on the Crystallization of Opal Structures
Martin Waleczek 1 Emma M. Hildyard 2 Jefferson Jean do Rosario 3 Slawa Lang 4 Josep M. Montero Moreno 1 Robert Zierold 1 Manfred Eich 4 Gerold Schneider 3 Kornelius Nielsch 1
1Universitauml;t Hamburg Hamburg Germany2University of Cambridge Cambridge United Kingdom3Hamburg University of Technology Hamburg Germany4Hamburg University of Technology Hamburg GermanyShow Abstract
Synthetic opals are suitable as a scaffold for the fabrication of inverse opal structures with a complete photonic band gap. The band gap is tunable by the geometry of the opal's building blocks, usually ceramic or polymeric spheres with a diameter of several hundred nanometers up to a few micrometers. The final structures can be effectively tuned to act as thermal barrier coatings with a complete photonic band gap in the infrared region. The optical features of these photonic crystals, however, are not only determined by the chosen building blocks, but also by their spatial arrangement or crystallinity.
In this work, the influence of a patterned template on the crystallization of an opal structure fabricated by means of vertical convective self assembly or with a slide coating technique is studied. Lines, cubic arrangements as well as hexagonal structures with periodicities in the range of 300 - 900 nm are chosen as lithographic patterns. These are introduced by one-step or two-step UV laser interference lithography applied to a single photoresist layer on top of a simple glass substrate. In this way, the pattern geometry—depth of the holes, periodicity at multiple angles—can be easily and precisely adjusted to the dimensions of the respective polymeric spheres used for opal deposition. After infiltration of the structure with a ceramic layer by Atomic Layer Deposition (ALD), a sequential self-limiting process used to conformally coat arbitrarily shaped structures with nanometer precision, the spheres are removed and the remaining inverse opal structure can be optically characterized.
Additionally, with these low cost substrates a comprehensive statistical study of the influence of a patterned template on the crystallization of opaline structures is feasible for the first time. We utilized the fast fourier transform of scanning electron mi