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.
4:45 AM -
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 hierarchica