Hong Jin Fan, Nanyang Technological University
Song Jin, University of Wisconsin-Madison
Mato Knez, Max-Planck-Institute MSP
Bozhi Tian, University of Chicago
Symposium Support Royal Society of Chemistry
JJ2: Nanoparticle Assembly in 3D Mesocale Structures
Monday PM, December 01, 2014
Hynes, Level 1, Room 103
2:30 AM - *JJ2.01
Self-Organization of Nanoparticles into Mesoscale Assemblies: From Fundamentals to Applications
Nicholas A Kotov 1 2 3 Bongjun Yeom 1 Yoonseob Kim 1 Jihyeon Yeom 1 Dawei Deng 1 Carlos A Batista-Silvera 1
1University of Michigan Ann Arbor USA2University of Michigan Ann Arbor USA3University of Michigan Ann Arbor USAShow Abstract
Intrinsic ability of nanoparticles (NPs) to self-organize can be seen virtually everywhere around us. Although omnipresent, the mechanisms of these processes are not well understood and include many surprises. One of the enigmatic aspects of these processes is the ability of large number of NPs to form mesoscale superstructures with high complexity. Two general classes of assemblies will be considered in this talk. Self-organized structures known as “terminal” cannot grow beyond a certain size. The second class of assemblies known as “extended” may continuously grow along specific directions. The distinction between these two cases will be made based on the balance of attractive and repulsive interactions between NPs and their spatial anisotropy. The fundamental problems associated with quantitative description of forces between NPs will be elaborated. It will be demonstrated that even small differences in directionality of NP interactions can lead to large structural effects in mesoscale. Vivid representation of such effects will be the formation of twisted chiral assemblies of NPs.
Practical relevance of terminal assemblies is based on their simplicity, versatility, and multifunctionality. Self-limited supraparticles are made from a variety of charged NPs as well as from their combinations with biomolecules. Chiral assemblies from gold NPs demonstrated exceptionally low detection limits for detection (LOD) of DNA and proteins. The practical relevance of extended assembles is enabled by their ability to produce electrically conductive submicro-, micro-, and macroscale structures. Oriented attachment processes typical for water-soluble NP makes possible epitaxial lattice-to-lattice connectivity for solution processable electronic devices.
3:00 AM - JJ2.02
Ultrasmall Nanoparticles in Laser Vaporization: ldquo;Building Blocksrdquo; in the Synthesis of 3D Mesoscale Architectures, 2D Nanosheets, Nanorods and Thin Films
David B Geohegan 1 Masoud Mahjouri-Samani 1 Kai Wang 1 Mengkun Tian 2 Gerd Duscher 2 Hao Hu 3 Hanno Weitering 3 Alexander Puretzky 1 Christopher M. Rouleau 1 Mina Yoon 1 Gyula Eres 4 Ivan Vlassiouk 5 Miaofang Chi 1 Juan Carlos Idrobo 1
1Oak Ridge National Laboratory Oak Ridge USA2University of Tennessee Knoxville USA3University of Tennessee Knoxville USA4Oak Ridge National Laboratory Oak Ridge USA5Oak Ridge National Laboratory Oak Ridge USAShow Abstract
Here we investigate ultrasmall nanoparticles (UNPs, < 3 nm) formed in the gas phase by pulsed laser vaporization as reactive “building blocks” in the catalyst-free growth of hyperbranched mesoporous nanoparticle architectures, crystalline nanorods, 2D nanosheets, and thin films by pulsed laser deposition (PLD). Nanoparticles synthesized during typical PLD conditions in background gases (typically >30 mTorr) preserve target stoichiometry, but their integration in films or nanostructures remains poorly understood due to the lack of in situ diagnostics. Here, temporally- and spatially-resolved gated-ICCD imaging, spectroscopy, particle sizing, and ion probes are employed as in situ diagnostics to understand and control the plume expansion conditions in order to synthesize UNPs of primarily oxides, although similar strategies are employed with metal chalcogenides for 2D materials. We first focus on the synthesis conditions, size and optical properties, and atomic structure of loose UNPs of TiO2, a workhorse wide-bandgap semiconductor, during PLV and PLD in background gas pressures. These UNPs serve as “building blocks” for the assembly of hyperbranched 3D mesoporous architectures at room temperature, but with increasing substrate temperature they become integrated into vertically-oriented crystalline nanorods, sometimes with unusual phases (e.g., TiO2(B)). Similar results will be shown for other oxides (e.g., SnO2, MgO, PbZr(x)Ti(1-x)O3). Atomic-resolution Z-contrast scanning TEM and EELS are described to characterize the stoichiometry, atomic structure, and electronic structure (band gap) of individual UNPs. Under typical conditions for the spatial confinement of the plume, ‘amorphous&’ TiO2 UNPs are formed which do not conform to a known TiO2 bulk phase. Crystal field splitting measured by EELS and XPS are used to assess the evolution of recognizable phases vs. size and evidence for doping. Computational modeling approaches (both force field and DFT) are described to understand the structure and stability of the observed UNPs, and to understand the size emergence of a stable bulk phase. Ex situ annealing experiments, carried out within HRTEM on heated grids, are used to understand the mechanisms by which gas-phase deposited UNPs become integrated into larger nanostructures and thin films. Methods are described to integrate UNPs during synthesis at lower substrate temperatures. These findings are crucial to understand stoichiometry transfer and film growth modes in PLD, catalyst-assisted nanotube and nanowire growth in PLV, and catalyst-free nanorod synthesis in NA-PLD.
Research sponsored by the U.S. Dept. of Energy, Basic Energy Sciences, Materials Science and Engineering Div. (synthesis science) and Scientific User Facilities Div. (characterization science).
3:15 AM - JJ2.03
Self-Assembly of Nanoporous Silica Shapes
Igor Sokolov 1 Vivekanand Kalaparthi 1
1Tufts University Medford USAShow Abstract
Nanoporous (also called mesoporous) silica material can be synthesized as particles of various morphologies. Specifically, co-assembly of organic liquid crystals with sol-gel silica precursor brings micron-size nanoporous particles of 3D complexity which is typically found only in the biological world. The particles possess well-defined uniform cylindrical pores which diameter can be chosen in the range between 2 and 10nm. The mechanics of self-assembly of those 3D shapes is not well understood as of yet.
Here we present the results of our studies to reveal this mechanism. We demonstrate that the process of self-assembly occurs in three steps: 1) the assembly of 20-50nm silica “seeds”, primordial silica nanoparticles which already have nanoporous structure, 2) aggregation of the seed particles into micron size particulates of undefined shape, 3) minimization and thermalization of the free energy of the particles assembled in step 2.
3:30 AM - JJ2.04
Principles of Programmable Architecture
Alexei Tkachenko 1
1Brookhaven National Laboratory Upton USAShow Abstract
Over the past decade, an impressive progress has been made in using the molecular recognition properties of DNA to control self-assembly of nanoparticles and colloids. Such particles when functionalized with DNA, represent a novel type of building blocks, and also open a new class of theoretical problems in statistical mechanics and soft condensed matter physics. In my talk I will discuss various aspects of this broad field that range from quantitative understanding of the interactions on the level of few particles, to properties of the resulting multiparticle structures.
The natural next frontier would be the control of the overall morphology of self-assembled mesoscopic objects, i.e. programmable architecture. I will review a number of possible strategies in attacking this problem, and present their theoretical analysis, numerical simulations and some early experiments. I will also make parallels between principles of programmable architecture with the examples of morphological control in biology
Research is supported by the U.S. DOE Office of Science and Office of Basic Energy Sciences under contract No. DE-AC-02-98CH10886
4:15 AM - *JJ2.05
Design of Composition-Matched Interfaces in Functional Nano- and Mesoscale Materials
Dmitriy S Dolzhnikov 1 Hao Zhang 1 Jaeyoung Jang 1 Jae Sung Son 1 Dmitri Talapin 1
1University of Chicago Chicago USAShow Abstract
Development of synthetic methods for well-defined nanostructures has introduced new approaches for engineering functional materials. Single- and multicomponent nanocrystal arrays provide a powerful platform for designing “programmable” solids with tailored electronic, magnetic, optical and catalytic properties. We develop approaches to improve control over structure and composition of individual nano-building blocks, particularly focusing on the understanding of collective properties of nano- and mesoscale assemblies. Efficient charge, energy and heat transport are critical for many nano- and mesostructured electronic and optoelectronic devices. By designing surface chemistry which removes transport bottlenecks at interfaces and grain boundaries, we demonstrated solution-processed semiconducting materials with impressive performance. The examples include solution processed field-effect transistors with electron mobility over 300 cm2/Vs, thermoelectric materials with ZT>1.2 and solar cells with the power conversion efficiency above 12%, all achieved through rational assembly of surface-engineered nanoscale building blocks. These examples demonstrate utility of engineered nanomaterials for real-world technologies and applications.
5:00 AM - JJ2.07
Directed Assembly of Nanoparticles into Colloidal ldquo;Moleculesrdquo;
Wan Zheng 1 Kristian G. Haner 1 Liangju Kuang 1 Hongjun Liang 1
1Colorado School of Mines Golden USAShow Abstract
Colloidal “molecules” comprised of hierarchically organized nanoparticles may become building blocks of new functional materials. Directed particle-particle bonding in a specific and reproducible manner is highly desirable but often challenging. Here we report a strategy toward that goal by directed-assembly of nanoparticles into well-defined “molecular” architectures via “click” reactions. Bonding structures were created on nanoparticles at controlled positions by modifying their surfaces with heterogeneously functionalized polymers bearing reactive “click” moieties. Highly selective and efficient “click” reactions are then conducted to covalently organize nanoparticles into colloidal “molecules”. We expect that these “molecular” architectures can be tuned via reaction stoichiometry and particle geometry. We will show our preliminary data on the successful assembly of gold nanorods into structurally defined heterogeneous architectures. We will also discuss the broad utility of this method to organize nanoparticles of different size and shape.
5:15 AM - JJ2.08
Fabrication of Three-Dimensional Photonic Structures Utilizing Composite Colloids
Tanya Shirman 1 Nikolas Vogel 1 Joanna Aizenberg 1 2
1Harvard Arlington USA2Wyss Institute for Biologically Inspired Engineering Cambridge USAShow Abstract
The 3D nanoporous structures of inverse opals (IO), synthesized from a sacrificial colloidal crystal template, are potential candidates for applications in photonics, sensing, and catalysis.1 In order to utilize these structures as functional materials, tuning the IO composition is extremely important. The incorporation of metal nanoparticles into IO results in coupling of photonic and plasmonic properties, as well as the additional introduction of catalytic properties, thus greatly expands the possible applications of these composite materials.2,3 Moreover, the precise control over metal nanoparticles distribution into inverse opals structures, in particular the controlled placement of such particles at the air/solid interface of the individual pores, results in a higher accessibility of nanoparticles. In this work we synthesized composite polystyrene (PS) colloids by covalent attachment of gold nanoparticles (AuNPs) to the chemically modified PS surface. These composite PS-AuNP colloids were subsequently used as colloidal templates for IO formation. The accessibility of AuNPs at the air/solid interface allowed further growth of nanoparticles at defined positions of the inverse opal structure. SEM and TEM measurements reveal the formation of ordered 3D porous structures with well controlled gold distribution. The use of these composite IO systems for catalytic applications will be demonstrated.
1. a) Freymann, G.; Kitaev, V.; Lotschzc, B. V.; Ozin, G. A. Chem. Soc. Rev., 2013, 42, 2528. b) Hatton, B.; Mishchenko, L.; Davis, S.; Sandhage, K. H.; Aizenberg, J. Proc. Nat. Acad. Sci., 2010, 107, 10354.
2. a) Tan, Y.; Qian, W.; Ding, S.; Wang, Y. Chem. Mater. 2006, 18, 3385. b) Yu, A.; Meiser, F.; Cassagneau, T.; Caruso, F. Nano Lett. 2003, 4, 177.
3. Y. Vasquez, M. Kolle, L. Mishchenko, B. D. Hatton, J. Aizenberg, ACS Photonics, 2014, 1, 53minus;60
5:30 AM - JJ2.09
Region-Selective Deposition of 3D Nanoparticle Assemblies by the Huisgen-1, 3-Dipolar Cycloaddition
Sebastian H. Etschel 1 2 Luis F. Portilla 2 Marcus Halik 2 Rik R. Tykwinski 1
1University of Erlangen-Nuremberg Erlangen Germany2University of Erlangen-Nuremberg Erlangen GermanyShow Abstract
All basic electronic devices are assemblies of several materials with different electronic properties. The challenge of large scale production is the correct assembly of those materials with precise control over layer thickness, interfaces and region-selectivity. The concept of self-assembly promises a highly reproducible and selective approach for the fabrication of functional and ordered nano-structures by cost-effective wet-chemical methods. The Huisgen-1,3-dipolar cycloaddition is known as a powerful tool for the immobilization of materials on functionalized substrates.[2,3] Additionally, the copper-catalyzed alkyne-azide cycloaddition (CuACC) delivers high yields at moderate reaction conditions and can therefore be used for various kinds of materials. In order to achieve region-selective deposition by this reaction, the surface needs to be pre-functionalized with attractive and repulsive domains. We demonstrate a general approach for hierarchical region-selective assembly of functionalized nanoparticles by using patterns of complementary self-assembled monolayers (SAMs) and a fluorinated alkyl-phosphonic acid. Our previous work has shown that AlOx nanoparticles can be functionalized with mixed monolayers of phosphonic acids, in order to fine-tune its chemical and physical properties. Deposition of the alkyne, respectively azide functionalized nanoparticles on the orthogonally azide, respectively alkyne terminated SAM patterns on the substrate by CuACC was achieved exclusively at the reactive centers. The first selectively immobilized layer of nanoparticles can then be further used for the deposition of orthogonally functionalized nanoparticles by a second CuACC reaction resulting in hierarchical 3D nanoparticle assemblies. The approach is expanded to various types of NP-cores (e.g. ITO, TiO2, or FeOx), which enables in principle the formation of electronic devices.
 J. C. Love, L. A. Estroff, J. K. Kriebel, R. G. Nuzzo, G. M. Whitesides, Chem. Rev. 2005, 105, 1103-1170.
 T. Lummerstorfer, H. Hoffmann, J. Phys. Chem. B, 2004, 108, 3963-3966.
 J. P. Collman, N. K. Devaraj, C. E. D. Chidsey, Langmuir, 2004, 20, 1051-1053.
 A. P. Upadhyay, D. K. Behara, G. P. Sharma, A. Bajpai, N. Sharac, R. Ragan, R. G. S. Pala, S. Sivakumar, ACS Appl. Mater. Interfaces,2013, 5, 9554-9562.
 L. Portilla, M. Halik, ACS Appl. Mater. Interfaces, 2014, 6, 5977-5982.
5:45 AM - JJ2.10
Mesoscale Computational Study of Nanoparticle Assembly in Immiscible Binary and Ternary Polymer Blends
Paul Millett 1 Joseph Carmack 1
1University of Arkansas Fayetteville USAShow Abstract
Discovering new approaches to self assemble nanoparticles (NPs) into mesoscopically-ordered structures can lead to novel materials with new functionality. A particularly fascinating tactic to control NP arrangements is to disperse them in a phase-separating fluid medium. This talk will present recent computational modeling results that explore and characterize the mutual evolution of dispersed NPs in binary and ternary polymer blends following a quench below the critical temperature inducing phase separation. The computational method used is a hybrid Brownian Dynamics-Cahn Hilliard model. The massive three-dimensional simulations specifically focus on chemically neutral NPs that segregate to polymer-polymer interfaces ultimately leading to stabilized mesoscale domains. The morphologies of both bulk and thin film samples will be presented. For thin film samples, the effect of an applied electric field in aligning the domains in the out-of-plane direction is also studied. Relationships between the average channel diameter, the channel density, and the interfacial NP packing fraction with varying NP volume fractions and polymer compositions will be presented. Extending these concepts to ternary polymer blends leads to expanded possibilities for unique composite structures, including various ‘trijel&’ morphologies. From a practical standpoint, these composites have applications as catalytic membranes upon selectively etching one of the polymer domains, thereby leaving mesoscopic pore channels with nanoparticle-coated surfaces.
JJ3: Poster Session I: 3D Mesoscale Architecture I
Monday PM, December 01, 2014
Hynes, Level 1, Hall B
9:00 AM - JJ3.02
Anomalous Light-Induced Microstructure Formation
Doyk Hwang 1 Jiwoong Kwon 1 Jong Woo Lee 1 Kyung Suk Min 1 Gi Rim Han 2 Inhae Zoh 1 Seong Keun Kim 1 2
1Seoul National University Gwanak-gu Korea (the Republic of)2Seoul National University Gwanak-gu Korea (the Republic of)Show Abstract
We discovered a highly anomalous light-induced phenomenon of light-absorbing materials on a substrate under an optical microscope. When liquids containing light-absorbing materials were irradiated with a visible laser light at high power (> 1 mW), a doughnut-shaped microstructure of a highly fluorescent character was formed on the surface of cover glass. In order to elucidate the origin of this novel phenomenon, we analyzed this structure by microscopic and spectroscopic techniques. We expect this result will find many applications including construction of a rigid, fluorescent marker on the glass coverslip.
9:00 AM - JJ3.03
Soft-Template-Based Carbonization Route to Highly Textured Mesoporous Carbon-TiO2 Nanostructures for Energy and Photocatalytic Application
Li Na Quan 1 Yu Jin Jang 1 Yoon Hee Jang 1 Saji Thomas Kochuveedu 1 Heejun Kim 1 Dong Ha Kim 1
1Ewha Womans University Seoul Korea (the Republic of)Show Abstract
We report a novel concept for the generation of mesoporous TiO2 and carbon-TiO2 nanostructures with highly roughened surfaces at the nanoscale and application for critical elements in high-efficiency photovoltaic devices or visible light active photocatalysis. Those structures were prepared using triblock copolymer P123 simultaneously as template and carbon source combined with colloid self-assembly. A commercially available P123 played key role in the generation of nanovoids within the hierarchical mesoporous TiO2 bead and also as a carbon source. Firstly, the photovoltaic device with optimized amount of mesoporous carbon-TiO2 beads, enhanced conductivity due to carbon moieties which contributed to the fast electron transfer and low recombination. Moreover, highly ordered hierarchical mesoporous TiO2 networks can provide fast electron transport paths, enhance light scattering, facilitate infiltration of the electrolyte, and ultimately increase the power conversion efficiency. It was observed that the incorporation of mesoporous carbon-TiO2 beads into the conventional photoanode of dye sensitized solar cells led to enhanced photovoltaic performance by ~25.78 %. Secondly, TiO2 has been recognized as representative metal oxide semiconductor material with excellent photocatalytic activity due to its good stability, nontoxicity, and UV absorbance. However, the lack of visible light activity has been a critical issue due to the relatively large band gap. Highly ordered mesoporous inverse opal nanostructures with nano-textured surface morphology and multiple-length scale nanopores provide increased light-activated surface area and scattering effect, leading to enhanced photoabsorption efficiency and the transport of matters. A significantly enhanced visible light photocatalytic activity was demonstrated for the mesoporous carbon-TiO2 inverse opals in terms of the degradation of p-nitrophenol and photoelectrochemical water splitting.
9:00 AM - JJ3.04
Miniaturization of Ion Beam Irradiation Induced Periodic Nanostructures on Germanium Surface
Kenji Morita 1 Koji Shigematsu 1 Arisa Matsumoto 1 Noriko Nitta 1 Masafumi Taniwaki 1
1Kochi University of Technology Kochi JapanShow Abstract
Ion beam irradiation is used widely in semiconductor manufacturing process for producing p-type and n-type materials. Generally, ion beam irradiation induces a damaged layer corresponding to the projected ion range on the semiconductor surface. Further irradiation transforms the damaged layer into an amorphous structure. However, porous structures, such as voids, holes, fibers with nano to submicron dimensions, are formed on Ge, GaSb, and InSb surfaces by irradiation. It is clarified that such phenomena occur as a result of migration of collision cascade generated point defects. Porous structures on the semiconductor surface have potential applications for electronic and photonic devices. The problem with those structures is lack of regularity. Therefore the authors proposed a nanofabrication technique, which is combination of top-down and bottom-up approaches utilizing focused ion beam (FIB) on the basis of those phenomena. First, ordered initial structures are formed on the surface by spot irradiation, and then the initial structures are developed by homogeneous irradiation. Formation of periodic nanostructures with 60 nm dot interval was achieved by this method on Ge surface in previous work. In this research, searching for best irradiation condition to fabricate the minimum nanostructures in Ge was performed. Those processes were carried out using 30 keV Ga+ in FIB (FEI Quanta 3D 200i) at room temperature and liquid nitrogen temperature. Single crystals of Ge (001) were used in wafer. The chamber vacuum was 5×10-4 Pa. Structural changes associated with ion beam irradiation were observed by a field emission scanning electron microscope (FE-SEM). The result showed that nanostructures with 30 nm dot interval were formed in low fluence irradiation at room temperature, although some structures were collapsed. Probably nanostructures were coalesced with neighbor structure due to small intervals, and the distance of point defect migration is longer than a wall thickness of nanostructures.
9:00 AM - JJ3.05
Anisotropically Functionalized Carbon Nanotube Array Based Hygroscopic Scaffolds for Water Harvesting from Air
Sehmus Ozden 1 Robert Vajtai 1 Pulickel M. Ajayan 1
1Rice University Houston USAShow Abstract
Fresh water is an ever decreasing resource that can be found in small amounts in almost every environment. In nature, there are many organisms, such as the Stenocara beetle which lives in the Namib Desert survives by drinking fog-water that collects on its wing case. The unique design of the Stenocara beetle&’s back involves randomly spaced bumps with hydrophilic peaks surrounded by hydrophobic areas the guide water into its mouth. The Stenocara beetle stands on a sand dune, facing into the morning wind at a forty-five degrees angle. With its head facing downward and its bottom upward, the minute water droplets from the fog collect on the superhydrophilic peak of each bump. When the water droplets grow big enough, they detach from the bump peaks, fall onto the superhydrophobic areas between the bump peaks and are guided downward to the beetle&’s mouth. Additionally, Stipagrostis Sabulicola, and Cotula Fallax, are some other organisms that are able to effectively capture water droplets from the fog of the morning desert by using hydrophilic/hydrophobic combinations. Here we report a new approach for anisotrophically functionalized vertically aligned carbon nanotube forest (NTF) as superhydrophilic/superhydrophobic. Due to combination of hydrophilic and hydrophobic surfaces, we were able to utilize the material for water collection from dry air and high humidity air. By this approach the water microparticles in air can be captured and stored in comparatively large amounts.
9:00 AM - JJ3.06
Analysis on Mesoscopic Phase Morphology of Organic Materials for Solar Energy Conversion
Hiroshi Mizuseki 1
1Korea Institute of Science and Technology (KIST) Seoul Korea (the Republic of)Show Abstract
Blended organic photovoltaic cells are of scientific and technological interest as they have the potential to become an attractive alternative for low-cost energy generation. However, the present efficiency of organic photovoltaic cells lies around 10%, much below the value for inorganic photovoltaic cells. Energy level, band gap, and mobility of organic materials are crucial factors in achieving high power conversion efficiency. From mesoscopic aspect, controlling the phase morphology of the two components (donor/acceptor) in the photoactive layer is important issue, because the exciton diffusion length in organic materials is of the order of 10 nanometers. The mesoscopic morphology of donor-acceptor organic materials have a huge effect on power conversion efficiency, because of most of the donor or acceptor domains are isolated or far from the electrodes (anode and cathode). This morphology leads to a long conduction path which causes possible recombination of the electron and hole pairs and lowers the efficiency of the cell. In the present study we have evaluated the phase morphology of donor-acceptor organic materials to realize a suitable high efficiency. This research used computational resources of the K computer and other supercomputers of the HPCI system provided by the RIKEN Advanced Institute for Computational Science, Cyberscience Center, Tohoku University, and Information Initiative Center, Hokkaido University through the HPCI System Research Project (Project ID: hp120010, hp140014). The authors would like to express their sincere thanks to the staff of the CCMS, IMR, Tohoku University for their continuous support of the SR16000-M1/320 supercomputing facility.
9:00 AM - JJ3.07
Mass Transport Behavior of Ionic Species inside Three-Dimensional Mesoporous Silica Thin Films
Kang-Yeong Kim 1 Joo-Young Lee 2 Geun Oh Kim 1 Seung-ik Jo 1 Young-Uk Kwon 1
1Sungkyunkwan University Suwon Korea (the Republic of)2Sungkyunkwan University Suwon Korea (the Republic of)Show Abstract
Mesoporous silica thin films (MSTFs), which were three-dimensional structure, have been prepared by the evaporation-induced self-assembly (EISA) method using a block copolymer F-127. We performed Low angle X-ray diffraction (XRD) on non-treated MSTFs and scanning electron microscope (SEM) on films electro-deposited with Pt to characterize films&’ structure. The non-treated films were equipped on Teflon cell and investigated how mass transport inside three-dimensional MSTFs by using cyclic voltammetry (redox species: Ru(NH3)63+Cl3 and supporting electrolyte: KCl). The results demonstrated that shape of redox curves of probe was influenced by concentration of electroactive species. At low concentration of redox probe, when scan rate was faster, difference between cathodic peak and anodic peak (ΔEpeak) was more reduced, which means adsorption of Ru(NH3)63+ on silica was much predominant than diffusion of Ru(NH3)63+ inside pore. At high concentration, these results were reversed. In this case, diffusion of Ru(NH3)63+ was much predominant that adsorption of Ru(NH3)63+ on silica wall. Adsorption of Ru(NH3)63+ on silica was caused by attraction between negative-charged silica (in neutral condition) and Ru(NH3)63+. To examine interactions between silica wall and Ru(NH3)63+, we added HCl and KOH to modulate the surface charge of silica. At acidic condition, the intensity of redox peak was decreased and positive-shifted from original-condition peak, which means repulsion between silica wall and Ru(NH3)63+ was occurred. At basic condition, that of redox peak was increased and negative-shifted from original-condition peak, which means Ru(NH3)63+ was more strongly attracted to silica wall and became stabilized. Also, we investigated the effect of nonelectroactive species by varying the concentration of supporting electrolyte. When the concentration of electrolyte was higher, the intensity of redox peak was more decreased. The reason was that the amounts of accumulated ions inside pore were larger with increasing the concentration of electrolyte, which hindered the attraction between silica wall and redox probe. Our research data provides a basic information for understanding the mass transport inside few nanometer-sized mesoporous thin films and promotes the application of mesoporous silica for catalysis, sensing, and membrane.
9:00 AM - JJ3.08
Structured Organic Films (SOFs) for Gas Separation
Brynn Dooley 1 Steven Risser 2 Matthew Heuft 1 Adrien Cote 1 Krenar Shqau 2 Jay Sayre 2 Michelle Chretien 1
1Xerox Research Centre of Canada Mississauga Canada2Battelle Memorial Institute Columbus USAShow Abstract
Separation of natural gas from CO2 requires an increased CO2 permeation rate as well as improved CO2/CH4 permselectivity. Most current materials investigated towards this end have been bound by the “Robeson tradeoff”. In order to exceed this upper boundary, the invention of innovative materials is required. Porous covalent organic frameworks (COFs) are powdered materials which have emerged as potential candidates for future gas storage applications. More recently we have developed chemistry and processing conditions which enable production of these covalently-linked organic materials as thin films (substrate-supported or free-standing) over macroscopic length scales. We refer to the resulting materials as structured organic films (SOFs). Researchers at the Xerox Research Centre of Canada and the Battelle Memorial Institute are currently collaboratively exploring the use of SOFs as permselective membranes for gas separation and / or storage.
This paper will present the chemistry and engineering used to create porous SOFs, which are expected to exhibit unique properties controlled by the specific chemistry and morphology of the building blocks. The physical, electronic, and transport properties were measured for a training set of porous SOF membranes. These results were used to develop models for both the permselectivity and mechanical properties of the membranes. This paper will then discuss synthetic directions to produce SOF membranes with enhanced permselectivity, and the extent to which this class of materials can exceed the limitations of the “Robeson tradeoff”.
9:00 AM - JJ3.09
Experimental Realization of the Odd-Even Effect in Wetting Properties of Self-Assembled Monolayers Depends on the Roughness of the Substrate
Lucas Benjamin Newcomb 1 Martin Thuo 1 Ian Tevis 2
1University of Massachusetts Dorchester USA2Iowa State University Ames USAShow Abstract
Self-assembled monolayers (SAMs) are a widely used platform for studying the physical and electronic properties of organic/organomettalic molecules. The quality, and hence properties, of simple n-alkanethiolate SAMs on Au or Ag have shown a dependency on the overall length of the molecule. The odd-even effect is one such phenomenon that is dictated by whether the n-alkanethiol has an odd or even number of carbons. This effect arises from differences in tilt angle, i.e., the orientation of the terminal -CH2CH3 moiety of these alkanethiols. Additionally, the difference in orientation of this terminal moiety is inverted when the underlying substrate is switched from gold to silver. Previously, this odd-even effect was reported to have no impact on the wetting properties of these SAMs. Laibinis and co-workers proposed that there was insufficient interaction between the water molecule and the SAM at the Van der Waals interface. Previous studies of the wetting of water on alkanethiol SAMs, however, were performed using as deposited metal (MAS) substrates which are known to be rougher than template stripped (MTS) ones. Interestingly, we observed that asperities on AuAS and AgAS are too large to produce a reliable monolayer, which is why the previous studies observed no odd-even effects. Investigation of the wetting properties of n-alkanethiolate SAM's on AuTS, however, revealed an odd-even effect. When the study was repeated with AgTS the inverse odd-even effect was observed albeit with a smaller variation in theta;s between the odds and the neighboring evens. We therefore infer that realization of subtle effects on the surface of the SAM is highly dependent on the quality of the underlying surface.
9:00 AM - JJ3.10
Using Kinetics and Ultracentrifugation to Prepare and Collect Discrete Nanoparticle Clusters Assembled via DNA Mediated Approaches
Alisha J. Lewis 1 Tennyson L. Doane 1 Kaitlin Coopersmith 1 Mark J. Bowick 2 Mathew M. Maye 1
1Syracuse University Syracuse USA2Syracuse University Syracuse USAShow Abstract
This presentation focuses on preparing clusters of gold nanoparticles with defined stoichiometry and symmetry. In our work, gold nanoparticles with sizes between 5 - 50 nm are assembled via DNA mediated interactions. The self-assembly kinetics are altered by manipulating interparticle energetics by changing DNA coverage, length, rigidity, and sequence, as well as and nanoparticle size. The self-assembled clusters are assembled at different stoichiometries and size ratios, collecting after appropriate reaction times, and purified via ultracentrifugation. The conditions for such assembly and purification will be discussed. The assembled clusters were characterized via dynamic light scattering (DLS), UV-visible spectrophotometry (UV-vis) and fluorescence spectroscopy. The morphology of the clusters were characterized by transmission electron microscopy (TEM) and in-situ cryo-TEM.
9:00 AM - JJ3.11
The DNA-Mediated Assembly and Purification of Multi-Color Qdot Clusters
Kaitlin Coopersmith 1 Alisha J. Lewis 1 Liliana Karam 1 Jan Borstelmann 1 Mathew M. Maye 1
1Syracuse University Syracuse USAShow Abstract
In this presentation we describe the preparation and purification of multi-color quantum dot clusters. Using purpose-built CdSe/ZnS quantum dots and rods modified with single stranded oligonucleotides (ssDNA), clusters with defined stoichiometry and emission wavelengths were constructed by DNA mediated interactions using a solid phase assembly approach. To control stoichiometry and to improve assembly yields, the clusters were assembled and released in a step-wise manner at a colloidal solid support. The quantum dots were phase transferred using a polymer wrapping approach, and conjugated with ssDNA via EDC/NHS and click chemistries. Importantly, the DNA modified conjugates, and the assembled clusters were purified via ultracentrifugation that resulted in a more reactive and colloidially pure system. The clusters optical characteristics were characterized by fluorescence spectroscopy and microscopy, and FRET analysis was utilized to probe energy transfer within the clusters. The cluster morphology and hydrodynamic properties were characterized by TEM and DLS, respectively. The use of these clusters for sensing and multi-color multiplexing will also be discussed.
9:00 AM - JJ3.12
Double Assembly: Oriented Attachment of CdTe Nanoparticles in Layer-by-Layer Film
Xianyong Lu 1 2 Nicholas A. Kotov 2
1Beihang University Beijing China2University of Michigan Ann Arbor USAShow Abstract
Cadmium telluride (CdTe) nanoparticles (NPs) are a promising type of nanomaterial with convenient properties for solution in processing of electrical devices. They are typically used as thin polyelectrolyte films where CdTe nanoparticles present advantages for advanced electronics. Layer-by-layer (LBL) assembly is one of the most versatile methods for preparation of organic-inorganic nanocompoistes and is based on sequential layering of inorganic nanoparticles and polymers. However, it is difficult to achieve highly conductive LBL films of nanoparticles. Here, we show oriented attachment of CdTe nanocrystals in LBL films. CdTe nanochains serve as charge-transport elements in the electronics. Oriented assembly of CdTe can not only increase conductivity, but also contributes to their mechanical properties.
9:00 AM - JJ3.13
Postsynthetic Encapsulation of Guests into Crystalline Porous Materials
Lien-Yang Chou 1 Frank Tsung 1
1Boston College Chestnut Hill USAShow Abstract
Crystalline porous materials can be engineered for drug delivery, sensing, and catalysis by the incorporation of functional guest molecules into their pore interiors. Metal-organic frameworks (MOFs) offer many opportunities for host-guest composites due to their well-defined and chemically tunable pore surfaces and unique properties such as framework flexibility and exchangeable ligands. Most of current MOF-guest composites are formed by diffusing guest molecules smaller than MOF aperture size and the small guests stay in MOF through electrostatic interactions. However, approaches for incorporating large and more diverse guests are still limited. Here, we introduce a new concept for incorporating large guests into MOF under linker exchange conditions. Expanded apertures created by the ligand exchange process allow large guest molecules to diffuse into the MOF pore. After guest loading, association of the ligand closes the large aperture, trapping the guest molecule in the MOF pore. This new approach to guest incorporation is expected to be general because framework linker exchange has been carried out under various conditions and exists in a large number of MOFs.
9:00 AM - JJ3.14
Assembly TiO2 and LiNbO3 Nanoparticles on Flexible Fiber Carbon Composite: Comparative Physical-Chemical Study
Neftali Lenin Villarreal Carreno 1 Ricardo Marques e Silva 1 Anderson Thesing 1 Vinicius Goncalves Deon 1 Igor Cherubin 1 Cesar Oropesa Avellaneda 1 Sonia Maria Sonia 2 Marcelo Ornaghi Orlandi 2 Maximo Siu Li 3
1Federal University of Pelotas Pelotas Brazil2UNESP Araraquara Brazil3USP Samp;#227;o Carlos BrazilShow Abstract
In the recent years, the new materials can be combined to fabrication of fiber carbon composite with specific properties as electrical, thermal and mechanical to development of alternative devices, such as photocatalyst system, energy storage material and piezoelectric material. The TiO2 and LiNbO3 nanoparticles have been attachment on carbon fiber, respectively, by previously surface modified, under self-assemble which were prepared by growing oxide particles on textured carbon assisted by hydrothermal synthesis in microwave furnace, the particles-fiber interactions are analyst by comparative study with sputtering deposition and conventional particles impregnation process, respectively. Hence this work, a carbon fiber roughness was modified by a chemical method using HNO3 97% at 103 °C, with exposure time 10, 20 and 30 minutes without degrade the fiber, additional the effect of various parameters such as concentration, pH, pressure (or temperature), time was investigated on hydrothermal synthesis. These sample were characterized by FE-SEM, showing to higher exposure times a densely packet of TiO2 and LiNbO3 nanoparticles monolayer, individual, are obtained. The photocatalytic activities were evaluated with dye (Rhodamine B) under visible-light irradiation, the kinetics study was monitored, the results showed that carbon fiber doped with ceramic oxide under visible light display efficient removal of hazardous materials. Additionally, X-ray diffraction (XRD), Raman, surface properties and conductivity studies were performed to investigate the morphology of flexible composite based on fiber carbon revealed the promising properties to fabrication of catalyst or device.
9:00 AM - JJ3.15
Enhancement of Catalytic Activity and Control of Reaction Pathway for Hydrocarbon Reforming over Mesoporous Zeolites Supporting Metal Nanoparticles
Kyungsu Na 1 2 Nathan Musselwhite 1 2 Xiaojun Cai 2 1 Selim Alayoglu 2 1 Gabor A Somorjai 1 2
1University of California, Berkeley Berkeley USA2Lawrence Berkeley National Laboratory Berkeley USAShow Abstract
Enhancement of catalytic activity and control of the reaction pathway to produce a high yield of desired product with 100% selectivity are of paramount interest for the development of energy-saving and eco-friendly catalytic reactions. In order to simultaneously achieve high catalytic activity with 100% product selectivity, catalytic systems should be tailored delicately. Synthetic development of metal nanoparticles (NPs) with various sizes and shapes can be one of the great contributions towards realization of this goal. Along with this, the development of various porous inorganic supports like mesoporous (2
9:00 AM - JJ3.16
Hierarchically Mesoporous Nanospheres with Controllable Acidic Properties
Yang Sik Yun 1 Hongseok Park 1 Danim Yun 1 Kyung Rok Lee 1 Chyan Kyung Song 1 Tae Yong Kim 1 Dae Sung Park 1 Jongheop Yi 1
1Seoul National University Seoul Korea (the Republic of)Show Abstract
Hierarachical structure have attracted great interest in recent years because of their large surface area, high porosity. In addition, their enhanced accessibility to the internal surface, originating from the hierarchical pores and small particle size in the nanometer range, is expected to be highly beneficial for reactions involving bulky guest molecules. Unfortunately, many hierarchically materials consist of a simple and catalytically inactive component, as exemplified by silica. For the practical application, such as catalysis, adsorption, etc., functionalization of hierarchical materials are required.
Among numerous method of functionalization, a direct synthesis and post-grafting method has been widely used. Although these conventional methods for functionalizing inert materials have been somewhat successful, they suffer from some important limitations. For instance, a direct sysnthesis route generally results in the collapse of structural uniformity when a large amount of heteroatoms are introduced. On the other hand, the post-grafting method can introduce a large amount of heteroatoms, but can lead to an inhomogeneous surface dispersion of functionalities. Accordingly, the alterantive functionalizing method should be developed.
Herein we developed an efficient method for functionalzing hierarchically mesopous nanospheres with controllable active sites. The nanosphere exhibits uniform shape, 3D wide-open pore (> 10 nm), and high surface area (ca. 500 m2/g) in a wide range of compositions. The incorporated functionality (acid properties; acid type, strength and amount) of the nanospheres are easily controllable with varying the Si/Al ratio in prepration procedure. The catalytic activity of the developed nanospheres was tested by reaction with bulky molecules (cracking of 1,3,5 triisopropylbenzene, hydrolysis of sucrose). The nanospheres showed the higher activity and stabililty compared to microporous HZSM-5 and mesoporous AlMCM-41 catalysts due to its high accessibility derived from their unique structure. The performance of the nanospheres in hydrolysis of sucrose was more than doubled than the reference catalysts.
9:00 AM - JJ3.17
Facile Preparation and Characterization of 3D Flower-Like Rutile Titania and Its Application to the Plasmonic Photocatalysis
Jayeon Baek 1 Chyan Kyung Song 1 Tae Yong Kim 1 Kyung Rok Lee 1 Hongseok Park 1 Danim Yun 1 Jongheop Yi 1
1Seoul National University Seoul Korea (the Republic of)Show Abstract
Titania is an attractive semiconducting materials due to its efficient charge separation and high carrier mobility. In addition, photocatalysis based on titania has attracted much attention for effective utilization of solar energy in environmental purification and water splitting for hydrogen generation. The incorporation of plasmonic nanoparticles onto wide-bandgap titania enables photocatalysis in the visible region as the strong surface plasmon resonance excitation of nanoparticles. When the 3D structure is applicable to the titania, the light-harvesting efficiency can be enhanced due to the plasmonic coupling.
Previously, the synthesis of submicro-3D flower-like titania needs the inert conditions due to the hygroscopic properties of titanium precursor. Here in, we developed the facile method for the 3D flower-like titania with rutile phase where average size is 600-700 nm. As the thermal treatment time increases, rutile nanorods aggregate on the pre-existing crossed titania structure resulting in 3D spherical shape. The gold nanoparticles are deposited on various titania including 3D flower-like rutile titania by simple impregnation method. As compared to the conventional system, the Au/3D flower-like titania was found to enhance the visible-light photocatalytic activity via methylene blue degradation. Furthermore, we proved and quantified the plasmonic coupling effect by photocurrent analysis, FDTD simulation, and photoluminescence spectroscopy.
9:00 AM - JJ3.18
Synthesis and Electrochemical Properties of Polypyrrole Conducting Polymer in Sheath Like Nanotube Arrays Structured over TiO2 for Supercapacitor Energy Storage Devices
Navjot K Sidhu 2 1 Alok C Rastogi 2 1
1State University of New York Binghamton USA2State University of New York Binghamton USAShow Abstract
Electrochemical energy storage in supercapacitor devices is emerging as prominent technology for high power applications in modern portable electronics for which material systems based on conducting polymers such as polypyrrole which exhibits pseudocapacitance due to charge transfer reactions is widely studied. Most studies focus on 2-dimensional (2-D) random microporous structures for high surface area ion accessibility. Our strategy is to develop electrodes in the 3-D nanoscale architecture for accelerate ion kinetics and pervasive ion access. We synthesized vertically aligned TiO2 nanotube ordered arrays as core and created conjugated polypyrrole conducting polymer nanotube sheaths for improved electrochemical energy storage.
The vertical TiO2 nanotube arrays as core of 3-D nanoscale electrode architecture were synthesized over Ti sheet by anodization at +30 V dc in ethylene glycol with 0.25 wt % NH4F. TiO2 nanotubes are electrically conducting and amorphous as shown by XRD studies. TiO2 nanotube arrays morphology is modified as close-packed 3-4 mu;m long and 45-50 nm diameter by adding 2% water. The redox active polypyrrole sheath is created by ultra-short pulsed current electropolymerization under the action of surfactant which homogeneously nucleates and uniformly deposits highly conjugated polypyrrole over inner and outer walls of TiO2 nanotubes. Polypyrrole sheath thickness is controlled through number, typically 10-110k pulse cycles each of 2 mA.cm-2 amplitude.
Electrochemical properties of the 3-D nanoscaled TiO2 nanotube core-polypy rrole sheath electrodes relevant to the energy storage were investigated. Zero current axis symmetric and rectangular cyclic voltammetry plots in -0.1 to 0.5 V range at variable 10-100 mV.s-1 scan rates testify highly pseudocapacitive electrode behavior. The redox processes are fast in such nanostructured electrodes. Detailed electrochemical impedance spectroscopy (EIS) studies at various polyprrole sheath thickness attained through controlled number of polymerization current pulses elucidate the electrochemical processes during the evolution phases of the polypyrrole sheath over TiO2 nanotube and the electrolyte interface. High areal capacitance density of 48 mF cm-2 and low charge transfer resistance 12 ohm.cm-2 with least ion diffusion limitation are realized at optimized polypyrrole sheath thickness. Raman spectra studies reveal anion at specific chain locations involve in the redox process. Energy and power density of the single electrode system was evaluated by systematic charge-discharge plots generated at different 1-3 mA.cm-2 current densities which show cyclic stability of 3-D core-sheath electrodes. This paper reports pulsed electropolymerization synthesis, structure and electrochemical aspects of the polypyrrole sheath structured over TiO2 nanotube core and describes the energy storage performance of such structures in the 3-D nanoarchitecture.
9:00 AM - JJ3.19
Synthesis and Application of Porous Poly(Amidoamine) Particles via Inverse Suspension Polymerization
Sanghwa Lee 1 Sangyoul Kim 1
1KAIST Daejeon Korea (the Republic of)Show Abstract
Poly(amidoamine)(PAMAM) can bind and separate heavy metal ions in aqueous solution. In this study, we developed a process to fabricate 50~300mu;m porous PAMAM particles by using silica particles. These porous particles were prepared via inverse suspension polymerization with acrylamide monomers and silica particles. The silica particles were then removed by hydrofluoric acid to produce porous particles. SEM images showed many small pores in PAMAM particles. Detailed synthesis and characterization of the particles and their swelling ratio and metal ion absorption behavior will be presented.
9:00 AM - JJ3.21
Fabrication of Small-Sized C60 Nanocrystals and Its Thin Film
Akito Masuhara 2 1 3 Toshimitsu Sato 2 Sadahiro Msuo 4 Jun Matsui 5
1Yamagata Univ. Yonezawa Japan2Yamagata University Yonezawa Japan3Research Institute for Tohoku Revitalization Yonezawa Japan4Kwansei Gakuin University Hyogo Japan5Yamagata Univ. Yamagata JapanShow Abstract
We demonstrate a simple technique to prepare uniform C60 nanocrystals ultara thin film. Solution process is a simple and low energy saving process for fabricating organic electronics devices. However, the organic materials should be soluble in a solvent. Usually, π-conjugated materials are used an organic semiconductor. These materials are less soluble because of the strong π-π interaction. Therefore, soluble groups such as alkyl chain are attached on to the π-conjugated molecules.
In this paper, we have successfully fabricated thin film using typical insoluble organic semiconductor materials such as pristine C60. Fullerene C60 is the attractive material for organic devices due to their high carrier mobility. In our method, fullerene C60 nanocrystals were fabricated by reprecipitation method and the nanocrystals are assembled in two- and/ or three-dimension using a liquid-liquid interfacial assembles technique and electrophoretic deposition method. We have reported that monodispersed C60 nanocrystals can be easily prepared prepared using the reprecipitation method. The shapes and innner structures of the resulting C60 nanocrystals were strongly dependent on the combination of good and poor solvents. In addition, we have succeeded in preparing layerd structure of C60 nanocrystals. Mono-nanocrystal layer can obtained by liquid-liquid interfacial assemble technique and multi-nanocrystal layer can obtained by electrophoretic deposition method. Details of the controlling the size, morphology and structures of fullerene nano/microcrystals will be discussed.
9:00 AM - JJ3.22
Mesoporous Graphene-Like Carbon Sheets: High-Power Supercapacitors and Outstanding Catalyst Supports
Pengfei Zhang 1 Sheng Dai 1
1Oak Ridge National Laboratory Oak Ridge USAShow Abstract
Nowadays, continuous scientific endeavors are being directed toward low-cost, mild, scalable and reliable synthesis of graphene-based materials, in order to advance various graphene-related applications. So far, specific surface areas of current bulk graphene powders or graphene-like nanosheets are yet much lower than the theoretical value (2630 m2/g) of individualgraphene, remaining a challenge for carbon chemists. Herein, mesoporousgraphene-like carbon sheetswith high specific surface area (up to 2607 m2/g) and high pore volume (up to 3.12 cm3/g) were synthesized by performing polyimide chemistry in the molten salt “solvent.” In this process, abundant pyromelliticdianhydride and aromatic diamine undergo polycondensation together with further carbonization in molten KCl-ZnCl2, in which in-situ formed linear aromatic polyimide with a sp2 hybridized carbon skeleton could be directly coupled and rearranged into two-dimensional graphene-like nanosheet around the “salt scaffold”. Carbon nanosheets with well-defined mesopores (~3.5 nm) could be easily obtained by washing salt melts in water, while those salts could be recovered and reused for subsequent reaction. The nitrogen atoms in amine also afforded the resulting carbon with uniform foreign atoms (nitrogen content = ~ 6%). Moreover, holey carbon sheets with well-dispersed and through-plane nanoholes (diameter: 5-10 nm) could be constructed by using different monomers. Being a potential electrode material in supercapacitor, the as-made carbon nanosheet possessed a significant specific capacitance (131.4-275.5 F g-1) even at a scan rate of 2000 mV s-1. Additionally, powerful nanohybrids of carbon sheet-Co3O4 were also prepared with good performance in the aerobic oxidation of alcohols and amines to aldehydes and imines, respectively.
This work was supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number ERKCC61
9:00 AM - JJ3.23
Fabrication of Core-Shell Type Hybridized Micro Particles Composed of Mesoporous Manganese Oxide and Fullerene C60 Nanocrystals
Ayaka Toba 4 Yasuhumi Hayasaka 1 Keigo Matsuda 1 2 Akito Masuhara 1 2 3
1Yamagata University Yonezawa Japan2Yamagata University Yonezawa Japan3Yamagata University Yonezawa Japan4Yamagata University Yonezawa JapanShow Abstract
#12288;We have successfully fabricated core-shell type hybridized micro particles composed of mesoporous manganese oxide (MPMO) and fullerene C60 nanocrystals (NCs). In the pseudo capacitor faradic and non-faradic charge storage occurred, which resulted in high charge density. Manganese oxide in one of the materials to apply in the pseudocapacitor because of it low material cost. However, manganese oxide has low electric conductivity, which limit their film thickness.
To obtain the psedocapacitor electrode materials with high energy density by low cost materials and energy saving method, core-shell type hybridized micro particles were fabricated. In the micro particles, MPMO acts as pseudocapacitor whereas C60 NCs act as conduction pass to connect each micro particles. The micro particles ware synthesized by reducing KMnO4 with maleic acid followed by co-reprecipitaion of C60 NCs on the MPMO micro particle. Scanning electron microscopy image showed a core-shell structure, which composed of C60 NCs as a shell and MPMO as a core with an average diameter of 10 mm. The electrochemical property of the core-shell micro particles as well as MPMO micro particles was studied by cyclic voltammetry. The charge amount of micro particles was doubled in MPMO particles, which suggests C60 NCs acts as conduction pass. The effect of size and the core-shell ratio to the charge storage will be discussed.
9:00 AM - JJ3.24
Particle-Nested Inverse Opal Structures as Hierarchically Structured Membranes with Tunable Separation Properties
Do Kyung Rhee 1 Pil J. Yoo 1
1Sungkyunkwan University Suwon Korea (the Republic of)Show Abstract
Multiscale porous architecture that comprises macroscale template containing mesoporous structures has drawn significant attention due to its advantages in highly increased surface area and enhanced mass transport characteristics. Therefore, recent researches have been focused on the applications of catalyst design for highly selective chemical reactions or electrodes for high capacity energy devices. In particular, as for a macroscale template, inverse opal (IO) structures based on colloidal self-assembly have been extensively explored because of their structural regularity and controllability. However, reported approaches of constructing double periodic IO structures have mostly relied on a means of filling ensembles of nanoparticles inside the unit hollow chamber of the IO template, thereby eventually disrupting the intrinsic porosity of the primary IO phase. Moreover, since the solidification process of the precursor is accompanied by inevitable inclusion of a number of defects and cracks as a result of large volumetric shrinkage, it has been inherently restricted to use these multiscale (double periodicity) porous structures for large-scale applications, such as membranes.
To overcome this limitation and realize the multiscale porous nanoarchitectures over a large area, in this study, we present a means of creating hierarchical IO structures using core-shell structured colloidal particles as a material for forming opal-phase self-assembly. By means of selective removal of the colloidal shell, instead of entirely dissolving the internal colloid, we eventually create the colloidal particle nested inverse opal (CPN-IO) structures. The resulting CPN-IO structures hold several structural advantages in that the internal porosity is readily tuned by the control over core-shell ratio of the colloidal particles and uniform-sized nanochannels can be created through the interconnected pores of the primary IO frame. Since the nanochannel size can be controlled in a range between 5 and 50 nm and the membrane structure is demonstrated over a large area (2-inch wafer) in the form of free-standing films, CPN-IO structures can be applied for the separation of nanoparticles with high selectivity. In addition, we present theoretical calculation for estimating the effective nanochannel size inside the CPN-IO by means of constructing a relevant geometric model.
9:00 AM - JJ3.25
Biotemplated Gold - Titania Hybrid Nanostructures for Photocatalytic Water Splitting
Sonal S Padalkar 1
1Iowa State University Ames USAShow Abstract
Natural biopolymer like cellulose is a promising alternate to conventional biotemplates like DNA, viruses and some proteins. Here cellulose fibers were used as a template for the synthesis of gold (Au) nanoparticles with the assistance of surfactant CTAB. Nanoporous titania (TiO2) was then synthesized on Au decorated cellulose via the sol-gel technique to form a hybrid structure. The plasmonic properties of Au nanoparticles were exploited to enhance photocatalytic performance of this biotemplated hybrid structure. The variation in the thickness of the TiO2 layer was also included in the study to obtain a most favorable hybrid structure for maximum hydrogen generation via water splitting during the photocatalysis experiment. Further the biotemplated hybrid nanostructure was also characterized by transmission electron microscopy to study the composition and structure of each component and interface.
9:00 AM - JJ3.26
Influence of 3D Mesoscale Structures on Phase Transitions of Confined Sulfur
Marie-Vanessa Coulet 1 Lei Yu 1 Philip LLewellyn 1 Renaud Denoyel 1
1CNRS - Aix Marseille Universitamp;#233; Marseille FranceShow Abstract
It is well established that confinement induces significant changes in the thermodynamic behaviour, structure and dynamics of the occluded molecular phases. For example a confined molecular fluid has a critical temperature lower than its bulk counterpart and the temperature difference increases with decreasing pore size. Similarly, the melting temperature of a confined solid may be shifted from the bulk value and the sign of the temperature shift will depend on the nature of the interaction between the confined liquid and the walls of the 3D mesoscale structure . As a last example, the dynamics of a liquids confined in mesoporous silica shows a pathological behavior characteristic for the type of matrix (ordered / disordered, connected or not) .
Unlike water and organic fluids [3,4], adsorption phenomena in chalcogens has rarely been studied from the viewpoint of thermodynamics, structure and dynamics. In this contribution, we present a study dealing with the 3D mesoscale confinement of sulfur. Sulfur is the most puzzling element in the chalcogen family, in both solid and liquid state. In the solid state it possesses a huge number of alloptropes  whilst in the liquid state a polymerization transition is observed. The confinement has been realized in different 3D porous structures which differ by their chemistry (carbon or silica based structure), their structure (crystalline or amorphous), their network type (ordered or disorderd) and their pore sizes. We will show how the nature of the 3D network influences the solid-solid phase transitions and the melting behavior. Finally the persistence or not of the polymerization transition will be discussed.
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 C. Alba-Simionesco et al., J. Phys. : Cond. Matter 18, R15 (2006)
 D. Morineau et al., J. Chem. Phys, 117 , 19, 8966 (2002 )
 R. Steudel and B. Eckert, Top Cur.Chem. 230,1 (2003).
9:00 AM - JJ3.27
3D Metal Oxide Nanowire Heterostructure Mesh Electrodes for Efficient Solar Water Splitting
Alireza Kargar 1 Sungho Jin 2 Deli Wang 1 2 3
1University of California-San Diego La Jolla USA2University of California-San Diego La Jolla USA3University of California-San Diego La Jolla USAShow Abstract
Solar energy is believed to be the ultimate energy source to meet the global energy demand due to the dramatic world population growth. Photoelectrochemical (PEC) cells harvest solar energy and convert it into hydrogen fuel through water splitting, a very promising sustainable clean and CO2-free energy solution that combines the energy harvesting and storage processes. Hydrogen fuel has higher energy density and zero carbon emission compared to hydrocarbons. It is broadly recognized that there is no single material that can meet all the requirements for efficient and durable solar hydrogen production. On the other hand, low-cost materials, facile and cost-effective fabrication techniques are necessary for practical solar hydrogen generation in large scales.
In this presentation, we report solution growth of earth-abundant, environmentally-benign metal oxide nanowire heterostructures grown on high-surface-area mesh substrates for cost-effective, high-efficiency, and scalable solar hydrogen production in a neutral solution. In particular, we present core/shell and branched nanowire heterojunctions made from different metal oxides such as Cu2O, CuO, ZnO, and TiO2. The integration of small and large bandgap metal oxide nanowires offers a unique combination of desired properties that are crucial to high-efficiency solar energy harvesting and hydrogen generation, including improved light absorption, enhanced charge separation/transportation/collection, increased reaction surface area, and improved gas evolution kinetics. Different characteristics of metal oxide nanowire heterostructure photoelectrodes, including morphology, atomic structure, PEC performances, solar conversion efficiency, and long-term stability are investigated in detail and will be presented.
Our achieved results reveal a promising practical solution for high-efficiency, sustainable, clean solar hydrogen fuel generation using cheap, nontoxic materials synthesized with low-cost, facile and scalable fabrication processes.
9:00 AM - JJ3.28
Optical Sensing in Nanoporous Bacteriophage-Based Networks via Localized Surface Plasmon Resonance
Matthew T. Klug 3 2 Noemie-Manuelle Dorval Courchesne 1 2 Po-Yen Chen 1 2 Nina Hong 4 Paula T. Hammond 1 2 Nicholas X. Fang 3 Angela M. Belcher 5 6 2
1Massachusetts Institute of Technology Cambridge USA2Massachusetts Institute of Technology Cambridge USA3Massachusetts Institute of Technology Cambridge USA4J.A. Woollam Co., Inc. Lincoln USA5Massachusetts Institute of Technology Cambridge USA6Massachusetts Institute of Technology Cambridge USAShow Abstract
Photoactive nanoporous films are assembled by cross-linking M13 bacteriophages using a layer-by-layer process. By genetically engineering the bacteriophage to display peptides with an affinity for noble metals, plasmonic nanoparticles can be dispersed throughout the thin film in a manner that avoids aggregation, enabling them to act as reliable probes for sensing the effective refractive index inside the film. Furthermore, the resulting plasmonic bacteriophage scaffold can act as a template to build crystalline titania nanoporous networks via biomineralization, allowing sensing to proceed in both biomolecular and inorganic films. This is possible because the localized surface plasmon resonance (LSPR) frequency of sub-wavelength gold nanospheres is very sensitive to the complex dielectric function of its surrounding medium. By combining Mie theory with effective medium theory, the absorption peak position of well-dispersed gold nanoparticles in the bacteriophage-film was predicted and found to be in excellent agreement with experimental measurements. Moreover, the analytical model developed herein allows the porosity of both the biological and semiconducting networks to be determined by simply measuring the absorption peak position of the gold nanoparticles with a spectrophotometer. It is expected that both the organic and inorganic nanoporous networks will find further use in biomedical and energy applications as slight changes in the local environment within the pores of the nanoparticle-loaded film can be detected by monitoring the LSPR peak position in the absorption spectrum.
9:00 AM - JJ3.29
Room Temperature Imprinting of Nano-Porous Glass Prepared from Phase-Separated Glass
Kenji Imakita 1 Takeshi Kamada 1 Minoru Fujii 1
1Kobe University Kobe JapanShow Abstract
Nanoimprinting lithography (NIL) has attracted a significant attention as a next generation patterning techniques due to its simplicity, versatility, low-cost, high-fidelity, and potential for achieving high throughput. It is developed now in many laboratories and efforts have been considerably increased toward the possible applications in electronics, photonics, and biology. NIL is a process based on mechanical deformation of a material to the shape of a mold. The preferred materials are thermoplastics and UV-curable resists due to their high formability by viscous flow. There are only a few reports on NIL for inorganic materials although there is a growing demand for inorganic materials with designed nanostructure on the surface.
Direct imprinting of porous substrate (DIPS) is a relatively new concept for patterning the surface of inorganics. Reusable stamps with sub-micrometer scale patterns were applied directly to nano-porous materials. This results in compression or crush of the porous network and transfers the stamp pattern onto the surface of the porous materials. The imprinting can be carried out at room temperature even if the material has high deformation point. This technique has been applied to porous TiO2 and Al2O3 prepared by anodic oxidation of Ti and Al substrates, and porous Au fabricated from phase separated Au-Ag alloy. The vertical and lateral resolutions of the imprinting have been reported to be below 5 nm and 100 nm, respectively .
In this work, we applied the DIPS techniques to porous glass prepared from conventional phase-separated glass. Rapidly-quenched homogeneous SiO2-B2O3-Na2O glass was heated at 575 oC for 1 hour to cause phase separation into a SiO2-rich and a B2O3-rich phase. The phase separated glass was then immersed in HNO3 to etch the B2O3-rich phase out leaving the SiO2-rich phase behind. The pore size is about 10 nm. The transmittance is as high as 90 % from the ultraviolet to near infrared region, which is superior to that of polymer materials such as PMMA. The imprinting was carried out at room temperature in air by using commercial quartz mold. The grating structure with the pitch of 100 nm was well transferred onto the surface of the nano-porous glass. The structure has high thermal durability up to 500 oC. The DIPS for phase separated glass is a facile and scalable approach for the patterning of inorganic surface, because of their simple fabrication processes, i.e., conventional melt-quenching and room temperature imprinting. It has potential applications in electronics, photonics, and biology.
 J. D. Ryckman, M. Liscidini, J. E.Sipe, and S. M. Weiss, Nano Lett, 11, 1857-62 (2011)
9:00 AM - JJ3.30
Using Electrospinning to Engineer Multi-Scale Structure for Integration into Meso-Scale Non-Chemical 3-D Nanofibers for Cimex Immobilization
Shan He 1 Linxi Zhang 1 Ying Liu 2 Miriam Rafailovich 1
1Stony Brook University Stony Brook USA2Stony Brook University Stony Brook USAShow Abstract
Electrospinning can integrate nano/micro-scale structures to build functioning meso-scale devices. Here we illustrate an example that 3D electrospun polystyrene fibers closely mimicking the unique architectures of multi-direction nano-spiderweb are being used to produce immobilizing devices for Cimex lectularius. These insects are very difficult to trap since they do not respond to lures, and are resistant to chemical solutions. Here we show how an electrospun network of surfactant modified polymer fibers can be used to immobilize the insects. The polymer network is carefully designed such that the diameter of the fibers fits exactly between the setae on the legs of the insect. The spacing between fibers is engineered to be on the micro scale such that the leg of the insect can penetrate. When the insect moves, the legs become trapped in a ratchet type of structure. The body of the insect is platelet like in order to distribute its weight over a large area. Hence the insects apply very little traction forces. In order for them to be trapped, the mechanical response of the fibers has to be specifically tailored so that it is elastically deformed, without fracturing or flowing. Hence the modulus has to be tailored within a narrow regime. We show how this can be accomplished using surfactants with optimized processing variables, increasing the surface charge of the fibers. When the stretching and lengthening of the polymer fiber takes place where solvent evaporating and the increased charges due to the surfactant within the polymer repelling each other. Due to the presence of the electrical charges on the fiber and inability of the fiber to discharge quickly, enhanced repulsion between the fibers, as deposited, cause them to be spaced out giving a fluffy 3 Dimension fiber ‘cloud&’ structure. We utilized Scanning Electron Microscope (SEM) and AFM nanoindentation to characterize the dimension and mechanical response of the fiber respectively. And we also characterized the fiber surface charge and electrical conductance by Zeta potential measurement. Carefully controlling and tailoring the electrospinning parameters we can now create a trap where multiple length scales are integrated to produce a meso-scale working device.
9:00 AM - JJ3.31
Investigation of Mesoporous Cerium Oxide Systems in the Low-Temperature Water-Gas Shift
Curtis Guild 1
1University of Connecticut Storrs USAShow Abstract
The synthetic parameters of cerium oxide supports are investigated though a sol-gel assisted route. The synthesized particles are found to be monomodal with respect to crystallite size, particle size, and pore diameter, and can be decorated easily with low concentrations of co-catalysts. The surface area and crystallite size are found to be linear relations with calcination temeprature. The activies of these systems are quantified by GC-TCD and RGA-MS studies, and qualifed by in-situ spectroscopic and diffraction studies at Brookhaven National Labs. In-Situ Raman, EXAFS, and PXRD studies show the cerium is reduced in operando from an average oxidation state of 4+ to 3+. The particles observed by TEM post reacitons are shown to be rounded, suggesting step defects as the active sites of the reaction.
9:00 AM - JJ3.32
Synthesis of Nickel Hydroxide Functionalized by Gold Particles for High Performance Pseudocapacitor
Sun-I Kim 1 Pradheep Thiyagarajan 1 Ji-Hyun Jang 1
1Ulsan National Institute of Science and Technology Ulsan Korea (the Republic of)Show Abstract
We introduce a facile method to synthesize nickel hydroxide (Ni(OH)2) with hierarchical structure, and to improve the pseudocapacitor properties of Ni(OH)2 by simply depositing conductive materials, gold particles. Pseudocapacitors using porous metal oxides have received great attention as an alternative energy device because of high specific capacitance, low cost, and easy control on the surface morphology, but suffered from poor conductivity and low cycle stability. In this study, we present an easy and cost-effective method to improve capacitance properties via simple deposition of gold nanoparticles on the surface of Ni(OH)2. By depositing gold particles, the specific capacitance of Ni(OH)2 was improved by 42% of that of the pristine sample and retained the high capacitance value at a high current density of 20 A/g and 5,000 cycles. This can be attributed to the fact that the deposited gold particles on the surface of semiconductor Ni(OH)2 create a virtual 3D conducting network via metal/semiconductor contact, which facilitates fast electron and ion transports, which can be confirmed by the EIS and I-V characteristic data. As the method is easy and efficient, this concept can be applied in many fields such as supercapacitors, gas sensors, and secondary batteries.
9:00 AM - JJ3.33
Designed Single-Step Synthesis, Structure, and Derivative Textural Properties of Well-Ordered Layered Penta-Coordinate Silicon Alcoholate Complexes
Xiansen Li 1 Vladimir K. Michaelis 2 Ta-Chung Ong 2 Stacey J. Smith 2 Robert G. Griffin 2 Evelyn N. Wang 1
1Massachusetts Institute of Technology Cambridge USA2Massachusetts Institute of Technology Cambridge USAShow Abstract
The controllable synthesis of well-ordered layered materials with speci#64257;c nanoarchitecture poses a grand challenge in materials chemistry. We report the solvothermal synthesis of two structurally analogous 5-coordinate organosilicate complexes via a novel transesterification mechanism. Since the polycrystalline nature of the intrinsic hypervalent Si complex makes it difficult to determine the crystal structure, a novel strategy incorporating the addition of a small fraction of B species as an effective crystal growth mediator and a sacrificial agent is proposed to directly prepare diffraction-quality single crystals without disrupting the intrinsic elemental type. In the determined crystal structure, two monomeric primary building units (PBUs) self-assemble into a dimeric asymmetric secondary BU via strong Na+-O2- ionic bonds. The designed one-pot synthesis is straightforward, robust, and efficient, leading to a well-ordered (10i)-parallel layered Si complex with its principal interlayers intercalated with extensive van der Waals gaps in spite of the presence of substantial Na+ counter-ions as a result of unique atomic arrangement in its structure. On the other hand, upon fast pyrolysis, followed by acid leaching, both complexes are converted into two SiO2 composites with BET surface areas of 163.3 and 254.7 m2/g for the pyrolyzed intrinsic and B-assisted Si complexes, respectively. The transesterification methodology which simply involves alcoholysis but without any hydrolysis side reaction is designed to have generalized applicability for use in synthesizing new layered metal-organic compounds with tailored PBUs and corresponding metal oxide particles with hierarchical porosity.
JJ1: 3D Mesoscale Fabrication
Monday AM, December 01, 2014
Hynes, Level 1, Room 103
9:15 AM - *JJ1.01
Programmable Assembly of 3D Mesoscale Architectures
Jennifer Lewis 1
1Harvard University Cambridge USAShow Abstract
The ability to pattern functional materials in planar and three-dimensional forms is of critical importance for several emerging applications. We are advancing programmable assembly methods based on microfluidics, 3D printing, and combinations thereof to enable the rapid design and fabrication of functional mesocale materials in arbitrary shapes without the need for expensive tooling, dies, or lithographic masks. In this talk, I will describe how we have created multiple architectures and demonstrated their use as carbon capture media, rechargeable batteries, and beyond.
9:45 AM - JJ1.02
lsquo;Smartrsquo; Building Blocks to Create Complex Structures in Additive Manufacturing
Esther Garcia-Tunon Blanca 1 Suelen Barg 1 Robert Bell 1 Eduardo Saiz 1
1Imperial College London London United KingdomShow Abstract
Key technologies, from energy applications to tissue engineering, demand complex and multifunctional structures with controlled morphological features at multiple scale lengths. Scientists in industry and academia in multidisciplinary fields are working towards developing novel manufacturing techniques to create new complex designs for a better performance. Additive manufacturing (AM) is now considered the next industrial revolution to produce complex 3D objects made of any possible material built up from nanoparticles or 1D and 2D materials. The challenge of making this prediction a reality, requires novel processing and post-processing approaches to broaden the materials palette in AM, and also to optimize their structural and functional properties from the nano to the macro scale.
Overcoming the challenge of processing very different materials, such as inorganic particles or 2D materials, requires the development of novel and flexible processing techniques that can be transferable to such different systems. Here, we propose the use of responsive molecules1 to functionalize the surface of ceramic particles and 2D materials to create ‘smart&’ building blocks. These ‘smart&’ building blocks can be assembled ‘on demand&’ by an external stimulus to create complex three-dimensional devices and structures. The responsive building blocks provide a wide range of soft-materials that can be used in several processing approaches. From molding, tape casting and emulsion templating (to create dense and porous hierarchical structures2), to the formulation of responsive inks with the right viscoelastic properties for filament 3D printing.
This talk will focus on the application of these ‘smart&’ building blocks in 3D printing of inorganic particles and graphene oxide sheets to produce freestanding 3D objects. We will present the surface functionalization mechanisms, rheological behavior of the responsive inks and the mechanical and functional properties of the 3D structures3.
1. Weaver, J. & Adams, D. J. Synthesis and application of pH-responsive branched copolymer nanoparticles (PRBNs): a comparison with pH-responsive shell cross-linked micelles. Soft Matter (2010).
2. García-Tuñon, D. E. et al. Designing Smart Particles for the Assembly of Complex Macroscopic Structures**. Angew. Chem. Int. Ed.52, 7805-7808 (2013).
3. Garcia-Tunon, E. et al. Printing in three dimensions with graphene. Submitted to Nature Nanotechnology
10:00 AM - JJ1.03
Prototypes of Soft Robotic Components Based on Novel Dynamic Patterns from Metallo-Dielectric Microcubes Driven by External Fields
Koohee Han 1 2 Charles Wyatt Shields IV 2 3 Bhuvnesh Bharti 1 2 Gabriel P. Lopez 2 3 Orlin D. Velev 1 2
1North Carolina State University Raleigh USA2NSF Research Triangle Materials Research Science and Engineering Center Durham USA3Duke University Durham USAShow Abstract
We have shown earlier how metallo-dielectric Janus/patchy spheres and microcubes, acquire complex polarization pattern in electrical and magnetic fields, leading to multidirectional interactions. We will present a novel approach for assembling metallo-dielectric microcubes into soft robotic components, which may find applications in fields such as microscale manufacturing and active microfluidics. Their potential is illustrated in a preliminary way by making motile, reconfigurable and self-folding chains from patchy microcubes, which possess repeated bending motions when actuated by an external magnetic field. The residual polarization of the metal-coated facets leads to directional forces between the neighboring particles and between the particles and the field. The dipole-dipole and field-dipole interactions lead to dynamic reconfiguration. Depending on the cube-to-cube binding conformations the assembled chains have distinct responses to the external field. In the case of cis-conformation, the junction between two cubes can be actuated reversibly by a pulsating magnetic field, whereas in the trans-conformation cube-to-cube overlap makes the junction rigid and thus restricts the bending of the chain. Consequently, the sequence of cis- and trans-conformations in the chain determines how the chain will respond and fold in a field and after it is turned off. We also seek to establish fundamental understanding and identify means of control of the chain dynamics. On this basis we design and demonstrate prototypes of soft microclamps capable of grabbing and transporting target objects.
10:15 AM - JJ1.04
3D-Printable High Particle Content Inks: A New Class of Materials for Biological, Energy, and Advanced Structural Applications
Ramille Shah 1 3 Adam Jakus 1 Alexandra Rutz 2
1Northwestern University Chicago USA2Northwestern University Chicago USA3Northwestern University Chicago USAShow Abstract
With the rapid global emergence and acceptance of additive manufacturing (AM) and 3D-printing (3DP) as a potentially transformational manufacturing method, the need for a broader array of 3D printable materials is becoming increasingly critical. Select AM and 3DP technologies, although effective, are often restricted to single material systems and have limited versatility, especially with respect to the introduction of new materials. We present here a universal 3D-ink formulation comprised of high volume fractions of nano-to-micron scale particles that can be 3D-printed at room temperature into small or large, complex 3D structures. The particle content may be as high as 90 vol.%, and the process can be applied to a wide variety of material systems. We demonstrate that this method can be used to create complex, user defined constructs with unique, functional properties from materials such as biologics (i.e. extra cellular matrix), graphene and carbon nanotubes, ceramics, metals, alloys, and hollow particles. In this manner, we are able to begin bridging the gap between intrinsic nano-to-micron scale material functionality and meso-to-macro scale device development and performance. In some instances, the as-printed object, referred to here as the green body, can be utilized as is. As an example, we demonstrate that hyperelastic mechanical properties can be imparted on high content ceramic composites through the 3DP process, which, when applied to biocompatible hydroxyapatite ceramic, is highly advantageous for biomedical applications. This process can readily be extended to 1D and 2D nanoparticle systems, such as carbon nanotubes and graphene, which we demonstrate to have enormous energy and biomedical potential in the form of 3D-printed constructs. Beyond the applicability of as-printed constructs, the high particle density also permits many of the 3D-printed structures to be effectively post-processed in a variety of ways, such as direct sintering to produce complex, dense ceramic structures or thermochemical reduction followed by sintering to produce complex metallic structures from ceramic precursor green bodies. Even planetary soils such as lunar simulant powders, which are comprised of more than a dozen distinct ceramic compounds, may be 3D-printed and post-processed to create structurally functional objects. This scalable process is also highly amenable to multi-material 3D-printing, which is necessary for producing a variety of new functional devices.
10:30 AM - JJ1.05
Electrochemical Synthesis of Highly Ordered Nanowire Arrays with Rectangular Cross-Section Using In-Plane Nanochannels
Philip Sergelius 1 Josep M. Montero Moreno 1 Wehid Rahimi 1 Martin Waleczek 1 Robert Zierold 1 Detlef Goerlitz 1 Kornelius Nielsch 1
1University of Hamburg Hamburg GermanyShow Abstract
Rapid and reproducible assembly of aligned nanostructures on a wafer-scale is a crucial, yet one of the most challenging tasks in the integration of nanowires into electronic circuits. We present the synthesis of a periodic nanochannel template designed for electrochemical growth of perfectly aligned, rectangular nanowires over large areas. The nanowires can be characterized in-situ using a pre-patterned multi-probe measurement platform. During the measurement the wires remain within a thick oxide matrix providing protection against breaking and oxidation. We use laser interference lithography, reactive ion etching and atomic layer deposition to create cm-long parallel nanochannels with dimensions below 40 nm. In a showcase study, pulsed electrodeposition of iron is carried out creating rectangular iron nanowires within the nanochannels. By design of the device, the grown wires are in contact with an integrated electrode system on both ends directly after the deposition. No further processing steps are required for electrical characterization, minimizing the risk of damage and oxidation. The developed nanowire measurement device allows for multi-probe resistance measurements and transistor applications. The guided, in-plane growth of electrodeposited nanowire arrays which are tunable in size and density paves the way for the incorporation of nanowires into a large variety of multifunctional devices.
10:45 AM - JJ1.06
Three-Dimensional Crystalline, Homogeneous and Hybrid Nanostructures Using Directed Assembly of Nanoparticles
Cihan Yilmaz 1 Arif Engin Cetin 2 3 Sivasubramanian Somu 1 Hatice Altug 3 Ahmed Busnaina 1
1Northeastern University Boston USA2Boston University Boston USA3Ecole Polytechnique Federale de Lausanne (EPFL) Lausanne SwitzerlandShow Abstract
#8203;Three-dimensional (3-D) homogenous and hybrid nanostructures have generated significant interest in many fields, including biomedical, optics, energy and electronics because they provide enhanced functionality and improved performance compared to planar nanostructures. Bottom-up directed assembly of nanoparticles have been considered as one of the best approaches to fabricate such functional and novel nanostructures. However, there is a dearth of studies on making crystalline, homogeneous and hybrid nanostructures. This requires a fundamental understanding of the forces driving the assembly of nanoparticles and precise control of these forces to enable the formation of desired nanostructures. Here, we demonstrate that colloidal nanoparticles can be assembled and simultaneously fused into 3-D solid nanostructures in a single step using externally applied electric field. By understanding the influence of various assembly parameters, we showed the fabrication of 3-D metallic, semiconducting and insulating materials with complex geometries such as nanopillars, nanoboxes, and nanorings with feature sizes from several microns down to 25 nm in less than a minute over large area (wafer scale). Using this technique, we have fabricated nanopillars made from Au, W, Cu, PSL, Si, SiO2, and CdSe and their hybrid derivatives. Novel heterojunctions such as metal-insulator, metal-semiconductor and semiconductor-insulator have also been created. The precise control of nanostructure dimensions is investigated via simulation results as well as various experimental parameters such as the voltage, frequency, time and particle concentration. TEM (transmission electron microscopy) and electrical characterizations reveal that manufactured gold nanostructures have polycrystalline nature and very low resistivity (1.96×10-7 Omega;middot;m). The fabricated novel 3-D nanostructures also demonstrate high optical quality supporting strong plasmonic resonances with line-widths as narrow as 13 nm. This enabled highly sensitive plasmonic based biosensing of A/G and Immunoglobulin G (IgG) proteins. These results indicate that the presented versatile, fast and controlled approach will facilitate the creation of novel 3-D nanomaterials while enabling scalable fabrication of hybrid nanoelectronic, optical metamaterial and biological devices.
11:30 AM - *JJ1.07
Locally Functionalized Inverse Opals as 3D Mesoscopic Colorimetric Probes
Ian B. Burgess 1 Natalie Koay 1 Joanna Aizenberg 1
1Harvard University Cambridge USAShow Abstract
Crack-free inverse-opal films exhibit a sharply defined threshold wettability for infiltration. This liquid-specific wetting behavior naturally couples to macroscopic color changes in these films. We are exploiting this effect in the development of simple and low-cost colorimetric indicators for liquid identification. Moreover, by functionalizing the surfaces of this porous structure with an environment-sensitive groups and observing the changes in the wetting behavior, we can follow the history of the exposure of the material to a certain stimulus. For example, crack-free inverse-opal films functionalized with a photoresponsive polyelectrolyte surface layer exhibits a highly selective wetting threshold that can be directly and continuously tuned by exposing the film to light. This approach may find applications in a broad range of technologies, including a convenient and direct method for liquid detection and encryption, or as a tag for low-cost monitoring of tampering or material aging.
12:00 PM - JJ1.08
Microsphere-Assisted Fabrication of Ultra-High Aspect-Ratio PDMS Micropillars for Bio-Inspired Acoustic Sensing
Jungwook Paek 1 Jaeyoun Kim 1
1Iowa State University Ames USAShow Abstract
The cricket&’s cercal receptors produce excellent performance in acoustic sensing with long and thin filiform hairs, attracting numerous attempts to mimic them. However, their replication requires high aspect-ratio micropillars, which is a great difficulty when attempted with conventional micro-fabrication techniques and PDMS. Here, we present a new technique based on the direct drawing technique incorporated with the in situ heating, which enables the realization of PDMS micropillars with unprecedented aspect-ratios (40 ~112). Our scheme also allows self-aligned capping of the