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spring 1998 logo1998 MRS Spring Meeting & Exhibit

April 13 - 17, 1998 | San Francisco
Meeting Chairs: John A. Emerson, Ronald Gibala, Caroline A. Ross, Leo J. Schowalter

Symposium O—Materials


C. Brinker 
Dept of Ceramic Synth & Inorganic Chem 
Sandia National Laboratories 
Advanced Materials Lab Bard Hall
Albuquerque, NM 87106 
505 272 7627

Emmanuel Giannelis
Materials Science & Engineering
Cornell Univ
Ithaca, NY 14853-1501

Richard Laine 
Dept. of MSE 
Univ of Michigan 
2114 H.H. Dow 
Ann Arbor, MI 48109-2136 

Clement Sanchez
Chimie de la Matiere Condensee
Univ Pierre et Marie Curie
Paris, 75005 FRANCE

Proceedings published as Volume 519 
of the Materials Research Society 
Symposium Proceedings Series.

* Invited paper

Chairs: C. Jeffery Brinker and Emmanuel P. Giannelis 
Monday Morning, April 13, 1998 
Golden Gate A2

8:20 AM OPENING REMARKS. R.M. Laine, C. Sanchez and C.J. Brinker. 

8:30 AM *O1.1 
NANOCOMPOSITE PLASTICS DERIVED FROM NANOSTRUCTURED POLYHEDRAL OLIGOMERIC SILSESQUIOXANE (POSS) CHEMICAL TECHNOLOGY. Joseph D. Lichtenhan1, Timothy S. Haddad2, Joseph J. Schwab2, Kevin P. Chaffee1, Patrick T. Mather31USAF Research Laboratory, Propulsion Sciences, Edwards AFB, CA; 2Hughes STX, USAF Research Laboratory, Propulsion Sciences, Edwards AFB, CA; 3USAF Research Laboratory, Materials Division, Wright Patterson AFB, OH. 

The recent establishment of a catalogue of nanostructured reagents based on mono and difunctionalized Polyhedral Oligomeric Silsesquioxanes (POSS), affords a new chemical arsenal for property enhancement in traditional polymer systems. POSS incorporation has been shown to improve the thermal stability, viscoelastic, and mechanical properties of thermoplastics, elastomers and rubbers (e.g., acrylics, styrenics, urethanes, silicones, etc.). In main-chain liquid crystalline polymers POSS incorporation has also been utilized to significantly reduce interfacial tension and to improve melt strengths. Our approach toward the incorporation of POSS into polymer systems has been to copolymerize, graft, or terminate chains with POSS groups. In this approach, the POSS entity is not utilized as a crosslinking point/agent. POSS reagents are physically large (approx. 15 ‰ diam. and 1000 amu) and nearly equivalent to most polymer dimensions. Therefore these nanosized chemical reagents can effectively enhance physical properties by providing localized structure (nanoreinforcement) and through controlling chain motion. Insights into the origins of property enhancements and into the nanostructral aspects of POSS-polymers will be discussed and supported through mechanical, rehological, thermal, and X-ray diffraction studies. A theoretical model for POSS-based nanocomposites will be proposed. 

9:00 AM O1.2 

Discrete polyhedral clusters containing silicon and oxygen have recently emerged as precursors to new families of network solids and hybrid inorganic/organic materials. Two broad families of polyhedral Si/O clusters exist: (1) spherosilicates, which are most often prepared by silylation of silicate solutions; and (2) polyhedral oligosilsesquioxanes, which are usually obtained from hydrolytic condensation reactions of trifunctional organosilicon monomers (RSiX3), hydrosilylation of hydridosilsesquioxanes or corner-capping reactions of two readily available silsesquioxane trisilanols. Both families have enormous potential as building blocks for advanced materials if cost-effective methods can be devised to produce appropriately functionalized Si/O frameworks on a large scale. We have developed a new strategy for preparing functionalized silsesquioxanes from fully-condensed frameworks, including R8Si8O12 frameworks. The salient feature of our approach is a general and remarkably selective method for effecting hydrolytic cleavage of a single framework siloxane linkage. The net monohydrolysis of many fully condensed can be accomplished selectivity with either complete retention or complete inversion of stereochemistry at Si. This talk will outline our revolutionary new method for preparing incompletely-condensed silsesquioxanes from fully-condensed [RSiO3/2]n frameworks. It will also describe how several readily available frameworks (including R8Si8O12 frameworks) might be used to manufacture precursors to hybrid inorganic/organic materials on a truly large scale. 

9:15 AM *O1.3 

The cubeoctameric silicate anion, Si8O208-, is one of spherosilicates which have been used extensively as a SiO2 source of molecularly designed SiO2-based materials. The silicate anion can be easily and selectively synthesized by controlled polycondensation of silicate anions with the aid of organic quaternary ammonium ions. This talk will first deal with procedures for preparing the silicate anion as the methanolic solution and solids, followed by some of its reactions. Since the structure of the silicate anion corresponds to the D4R secondary building unit of zeolites, the anion is expected to give porous materials by further condensation without breakdown of the silicate structure. Some examples of Si8O208--derived porous materials, organic-silica hybrids in which the cubic core is linked via the dimethylsilyl group and multi-component inorganic porous bodies with a specific surface area of over 400 m2 g-1 after heat-treatment at 800 oC, will also be presented. 

9:45 AM O1.4 
INORGANIC/ORGANIC HYBRIDS TAILORABLE AT THE MOLECULAR LEVEL. Richard M. Laine, Macromolecular Science and Engineering Center, and Departments of Chemistry, and Materials Science and Engineering, University of Michigan, Ann Arbor, MI. 

This presentation will provide a general overview of the design and synthesis of inorganic/organic hybrids wherein control of properties is dictated by the properties of the component pieces used in assembling the hybrid. The synthesis and properties of cubic polyhedral silsesquioxanes [cubes] will be used to illustrate specific concepts. 

10:30 AM O1.5 
CHARACTERIZATION OF EPOXIDE FUNCTIONALIZED SILSESQUIOXANES AS POTENTIAL UNDERFILL ENCAPSULANTS. Eric K. Lin, William E. Wallace, Wen-li Wu, NIST, Polymers Division, Gaithersburg, MD; Chunxin Zhang, Richard M. Laine, University of Michigan, Depts. of Mat. Sci, Chem., and the Macromol. Sci. and Eng. Center, Ann Arbor, MI. 

In electronics packaging, underfill encapsulants are needed to improve package reliability in flip chip devices. The underfill generally consists of an epoxy resin filled with silica particles and is designed to reduce the stress arising from the difference in the thermal expansion between the silicon die and the substrate. Currently, concerns about the flow of the silica particles and surface phenomena are arising as electronics packages reduce in size. Newly developed epoxide functionalized octametric silsesquioxanes provide an intriguing alternative to current formulations. These single-phase inorganic/organic hybrid materials may have the properties of the filled materials without the concerns arising from the filler particle size distributions. The physical properties of the functionalized silsesquioxanes are measured with respect to the critical parameters for underfill materials. Measurements of properties such as the coefficient of thermal expansion, the amount of water absorption, and density are performed to evaluate the suitability of these materials as potential underfill encapsulants. 

10:45 AM O1.6 
POLYHEDRAL OLIGOMERIC SILSESQUIOXANES (POSS): SILICON BASED MONOMERS AND THEIR USE IN THE PREPARATION OF HYBRID POLYURETHANES. Joseph J. Schwab, Hughes STX, Air Force Research Laboratory, Edwards AFB, CA; Joseph D. Lichtenhan, Micheal J. Carr, Kevin P. Chaffee, Air Force Research Laboratory, Rocket Propulsion Sciences, Edwards AFB, CA; Patrick T. Mather, Angel Romo-Uribe, Air Force Research Laboratory, Wright-Patterson AFB, OH. 

Polyhedral Oligomeric Silsesquioxanes (POSS) are unique hybrid inorganic/organic reagents composed of discrete silicon-oxygen frameworks. Appropriately functionalized POSS monomers represent an entirely new chemical technology for the preparation of new hybrid polymers, in which the inorganic portion of the hybrid is covalently linked to the organic polymer chain. When incorporated into polymer systems their unique combination of size and composition allows POSS reagents to affect the local structure of the polymer chain and to control the chain motion. Recently our efforts have focused on the synthesis of POSS containing monomers with suitable functionalization for the preparation of POSS-based polyesters, polycarbonates and polyurethanes. Towards this end, we have prepared a series of diol fuctionalized POSS monomers based on bisphenol A and trimethyolpropane. In the present work, both the POSS-bisphenol A and POSS-trimethylolpropane monomers were used in the preparation of a series thermoplastic polyurethane elastomers. The POSS monomers readily react with diisocyanates to give hybrid POSS-polyurethane copolymers, in which the POSS monomers function as the short chain diol extenders. The POSS-polyurethanes were prepared using both solution and melt polymerization techniques, and their physical and mechanical properties compared to polyurethanes prepared using the identical non-POSS containing monomers. In this presentation we will report our preliminary results on the synthesis of both the monomers and the polymers, as well as the physical and mechanical properties of the hybrid urethane polymers. 

11:00 AM *O1.7 
{(BuSu)12O14(OH)6}X2 AND {BuSuO(O2CR)}6, TWO VERSATILE TYPES OF NANOBUILDING BLOCKS FOR TIN BASED HYBRIDE MATERIALS. Francois Ribot, Christophe Eychemne-Baron, Clement Sanchez, Universite P. et M. Curie/CNRS, Chimie de la Matiere Condensee, Paris, FRANCE. 

The nanobuilding block route to hybrid organic-inorganic materials is based on a controlled assembling or well defined nanoscale objects whose structural features are retained through out the process. This approach allows a rational design of novel materials. With the aim to prepare model materials in which the organic/inorganic interface can be tailored, the nanobuilding block route has been developed with monoorganotin oxo-clusters. Indeed, with such species the links between the organic and the inorganic components can involve Sn-C bonds, but also complexation of the metallic centers or cation-anions in some cases. Butyltin oxo-clusters corresponding to (BuSn)12O14(OH)63+(RSO3-)2 with R : 4-CH3C6H4, 4-H2NC6H4, H2C=CHCONHC(CH3)2CH2, have been prepared from BuSnO(OH) and the corresponding sulfonic acids. Butyltin oxo-clusters of the same structure, but involving change compensating anions other than sulfonates have also been performed by exchangec reaction from {(BuSn)12O14(OH)6} (O3SC6H4CH3)2. A second type of butyltin oxo-clusters, {BuSnO(O2CR)}6, which involve complexing carboxylates, has been prepared from {(BuSn)12O14(OH)6}X2(X=O3SC6H4NH2 or OH) and caboxylic acids, RCO2H with R: C(CH3)=CH2, 4-C6H4CH=CH2, 4 (CH2)3C6H4CH=CH2, 4-C6H4NH2, 4-C6H4OH, 3,5-C6H3(OH)2. Solution and/or solid state (MAS) 119Sn NMR has been used to characterized these different oxo-clusters. Finally, the possibility to assemble some of these oxo-clusters into hybrid materials has been evaluated. 

11:30 AM O1.8 
Transferred to O8.33 

Chairs: Isao Hasegawa and Joseph D. Lichtenhan 
Monday Afternoon, April 13, 1998 
Golden Gate A2
1:30 PM *O2.1 
NEW PREPARATIVE METHODS FOR ORGANIC-INORGANIC POLYMER HYBRIDS. Yoshiki Chujo, Dept of Polymer Chemistry, Kyoto University, Yoshida, Sakyo-ku, Kyoto, JAPAN. 

This paper describes new methods for the preparation of organic-inorganic polymer hybrids. (1) In-situ polymerization method: The radical polymeri zation of N,N-dimethylacrylamide or styrene was carried out simultaneously t ogether with the sol-gel reaction (hydrolysis and condensation of alkoxysila nes) to produce homogeneous and transparent polymer hybrids. IPN (Interpen etrating polymer network) hybrids were prepared by this method using bifunct ional vinyl monomers (methylenebisacrylamide or divinylbenzene). The IPN p olymer hybrids obtained showed excellent solvent-resistant properties. (2) In-situ hydrolysis method: The sol-gel reaction of tetraethoxysilane in th e presence of poly(vinyl alcohol) produced only phase-separated materials du e to the aggregation of alcohol groups within organic polymer segments. Th us, the acid-catalyzed sol-gel reaction of tetraethoxysilane was carried out in the presence of poly(vinyl acetate). During the formation of silica mat rix, the acid-catalyzed hydrolysis of poly(vinyl acetate) took place. As a result, the homogeneous polymer hybrids consisting of silica gel and poly(vi nyl alcohol) were successfully obtained. (3) Aromatic interaction between organic and inorganic matrix: The combination of polystyrene and tetrameth oxysilane produced only turbid materials. On the other hand, in the presen ce of polystyrene, the sol-gel reaction of phenyltrimethoxysilane gave homog eneous polymer hybrids. In this reaction, the interaction of phenyl groups of polystyrene and phenyl groups of silica gel matrix was found to play an i mportant role for the preparation of homogeneous polymer hybrids. By using this idea, the polymer hybrids based on polycarbonate or poly(diallyl phthal ate) were also prepared starting from phenyltrimethoxysilane. 

2:00 PM O2.2 
Transferred to O8.31 

2:15 PM *O2.3 
COMPOSITION-STRUCTURE RELATIONS IN ORGANICALLY MODIFIED SOL-GEL MATERIALS. Ulrich Schubert, Guido Kickelbick, Nicola Husing, Gregor Trimmel, Institut fur Anorganische Chemie, Technische Universitat, Wien, AUSTRIA. 

Organically substituted metal and semi-metal alkoxides are used to modify and functionalize sol-gel materials. The properties of such materials are not only influenced by their chemical composition, but also by the arrangement of the organic and inorganic building blocks. This issue will be discussed for two types of compounds. Hydrolysis and condensation of Si(OR)4/ R'Si(OR)3 mixtures can be controlled that the organic groups are located at the inner surface of the gel network. Unless the group R' has basic properties, it does not significantly influence the built-up of the gel network. However, the Si(OR)4 / R'Si(OR)3 ratio influences the size of the network-forming structures. This is due to the fact that sol-gel processing of such two component mixtures is basically a two-step process. Reaction of metal alkoxides E(OR)n with carboxylic acids gives the organically modified precursors E(OR)n-m(OOCR)m. Their controlled hydrolysis often results in clusters of the type EOw(OH)x(OR)y(OOCR)z which can be conceived as models for the structural organization of the building blocks from which hybrid materials are composed. Several titanium and zirconium clusters were structurally characterized, their core being related to crystalline TiO2 or ZrO2. Only when the metal / carboxylate ratio exceeds a certain limit, the structures become less condensed. This limit is smaller for Ti than for Zr because of the higher coordination number of Zr. 

2:45 PM O2.4 
THE INFLUENCE OF SUBSTITUTION GEOMETRY ON THE SOL-GEL CHEMISTRY AND FINAL PROPERTIES OF VINYL-BRIDGED POLYSILSESQUIOXANES. Joseph P. Carpenter, Douglas A. Loy, Stacey A. Yamanaka, Mark D. McClain, Encapsulants and Foams Department, Sandia National Laboratories, Albuquerque, NM; Kenneth J. Shea, John Greaves, Dept. of Chemistry, University of California, Irvine, CA. 

The sol-gel polymerization of bis(triethoxysilyl)ethenes is strongly influenced by the orientation of the two silyl groups around the vinyl bridge. When the silyl groups are in a trans configuration, linear acyclic polymerization is observed. However, the cis isomer polymerizes through a series of cyclic condensation reactions in which the formation of seven-membered rings is repeated to construct the polymer network. The effect of the different polymerization processes on the final morphology and porosity of these materials was studied by SEM and nitrogen sorption porosimetry. The trans isomer yields polymers that are strictly microporous, while the polymers formed from the cis isomer have large mesoporous and macroporous domains. 

3:00 PM *O2.5 
THE DESIGN OF SELECTIVE CATALYSTS FROM HYBRID SILICA-BASED MATERIALS. Joël J.E. Moreau, Laboratoire de Chimie Organométallique, Hétérochimie Moléculaire et Macromoléculaire. Montpellier, FRANCE. 

The sol-gel processing of appropriated molecular precursors easily lead to a variety of hybrid organic-inorganic materials. Their preparation in a controlled way can lead to material with intrinsic properties. For example, the sol-gel approach is increasingly becoming an interesting way to prepare heterogeneous catalysts. Hybrids have been used recently to obtain dispersed metal species or particles on oxide supports. The paper will focuss on the use of hybrids for the preparation of selective catalytic material by design. The tailoring of the pore structure of silicas, under mild reaction conditions, based on the temporary introduction of various organic substructures in the hybrid network of polysilsesquioxanes gels will be discussed. Also the preparation of new chiral hybrid supports for enantioselective catalysis will be presented. 

3:30 PM *O2.6 
HYBRID INORGANIC-ORGANIC SOL-GEL DERIVED ABRASION RESISTANT COATINGS. Kurt Jordens, Chenghong Li and Garth Wilkes, Garth Wilkes, Department of Chemical Engineering and Department of Chemistry, Polymer Materials and Interfaces Laboratory, Virginia Polytechnic Institute and State University, Blacksburg, VA. 

Transparent coatings have been prepared by a modified sol-gel process for purposes of developing abrasion resistant surfaces for both metallics and polymeric substrates. For example, the low molecular weight organic molecule, diethylenetriamine, has been reacted with isocyanatopropyltriethoxysilane to generate a hybrid inorganic-organic monomer. This species is then co-reacted as catalyzed by the addition of aqueous acid but also additional metal alkoxide (e.g. tetramethoxysilane) can also be added for purposes of increasing the inorganic content of the final coating material. Following the spin coating of the initial reactants onto a prepared substrate, be it metallic or polymeric, curing occurs by the process of hydrolysis and condensation. The degree of thermal cure is dependent upon the substrate and the nature of the coating formulation. Many other possible routes for developing unique features of the abrasion resistant coatings will be discussed (e.g., UV stabilization). Abrasion testing has been conducted utilizing a Taber Abraser with CS-10 wheels. In the case of the metallic substrates, highly abrasion resistant coatings have been developed for stainless steel, copper, brass and polished aluminum substrates where the coating thickness if of the order of a few microns and the cure temperatures are typically less than 180ºC. As expected, increasing the content of the metal alkoxide relative to the functionalized organic improves the abrasion resistance of the resulting coating but an upper limit exists due to potential cracking of the inorganic rich systems. The influence of catalyst, hydrolysis time and hydrolysis ratio is also of importance to the specific coatings developed. Consideration of these variables will be taken into account to illustrate gelation times can be influenced as can the nature of the abrasion resistance of the final coating. Examples will also be discussed with respect to the development of abrasion resistant coatings for bisphenol-A polycarbonate as well as for CR39 carbonate. 

4:00 PM O2.7 
DENDRIMER-BASED NANOCOMPOSITES. Lajos Balogh and Donald A. Tomalia, Michigan Molecular Institute, Midland, MI. 

A proven and versatile strategy for the fabrication of novel nanocomposites will be presented using dendrimers either as nanoscaffolding or container molecules. The fundamental advantage for using dendritic polymers is their well defined composition and architecture. They are able to pre-organize guests into their interior or onto their surface by means of interior ligand-structure and/or variable surface structure. In these dendrimer-based nanocomposites the size, shape and size-distribution of the dispersed phase(s) or material(s) are created, determined and controlled by an appropriate dendritic polymer. Combinations of dendritic building blocks, (i.e., dendrimers, dendrons, dendrigrafts and hyperbranched polymers) into multiple structures with 0-D, 1-D, 2-D and 3-D features such as separate macromolecules, chains, films, covalent clusters, crosslinked dendrimers and other dendritic polymers afford a wide repertoire of structures and architectures for nanocomposite preparation. The concept will be demonstrated with poly(amidoamine) (PAMAM) dendrimers which have been employed for creating novel, soluble metal sulfide and metal(0) nanocomposites at room temperature, using post-complexation chemistry. Characterization of the resulting nanocomposites has been carried out by SEC, TEM, SEC, capillary electrophoresis, HPLC, UV-visible spectroscopy, 1H and 13C NMR, TGA, DSC, X-ray and neutron scattering, etc. These novel materials display new and surprising physical/chemical properties (such as solubility, optical, electronic, magnetic, reactivity, selectivity, etc.). Many of the described materials herein have never existed before. This general method provides a simple and economic way to prepare unique nanosized materials with many potential applications. 

4:15 PM O2.8 
NORBORNENE GROUP FUNCTIONALIZED SILANES AS NEW SOL-GEL PRECURSORS, Herbert Wolter, Werner Storch, Fraunhofer-Institut fuer Silicatforschung, Wuerzburg, GERMANY; Norbert Moszner, Ulrich Salz, and Volker Rheinberger, Ivoclar AG Schaan, Liechtenstein, GERMANY. 

As a consequence of the growing interest in sol-gel precursors which allow the formation of inorganic-organic copolymers with low shrinkage a new class of oligo-norbornene substituted alkoxy-silanes were developed. These silanes were synthesized e. g. by addition of the NCO-group of 3-isocyanatopropyltriethoxysilane to OH-substituted norbornene monomers obtained by Diels Alder reactions of corresponding (meth)acrylates with cyclopentadiene. Hydrolysis and condensation of the alkoxy groups (sol-gel step) leads to solvent free liquid resins which can be cured in combination with multifunctional thiols by a radical induced thiol-en-polyaddition mechanism. The synthesis of a number of different oligo-norbornene silanes, and the corresponding inorganic condensates (liquid resins) as well as first results of the thiol-en-polyaddition will be discussed. 

4:30 PM O2.9 
HYBRID POLYMERIC MATERIALS - POLYPHOSPHAZENE BACKBONES FOR SILOXANES AND ORGANIC POLYMERS. Guido Kickelbick, Peter J. Miller, Krzysztof Matyjaszewski, Dept of Chemistry, Carnegie Mellon University, Pittsburgh, PA. 

The coupling of inorganic and organic macromolecular systems provides one route to new hybrid materials. In this report we present our efforts in the use of polyphosphazenes as a backbone in combination with other macromolecular components. For example, the Sol-Gel process was used to obtain a second siloxane network. Additionally, Atom Transfer Radical Polymerization (ATRP) was used to achieve well-defined graft copolymers with various monomers and variable graft densities. For model studies the 2,2,4,4,6,6- 
hexachlorocyclotriphosphazene was substituted with precursors for ATRP to give stars with a phosphazene core surrounded by various organic polymers. The polyphosphazene backbone was prepared by two different processes. First, the ring opening polymerization of the 2,2,4,4,6,6-hexachlorocyclotriphosphazene was followed by a substitution of chlorine with functionalized nucleophiles. The second approach was based on the controlled polymerization of substituted phosphoranimines, providing control over the molecular weight and rate of polymerization. The properties of the resulting materials were characterized by several analytical methods like NMR, GPC, DSC and TGA. 

4:45 PM O2.10 

The dispersion of a polymer (polysiloxane, polyphosphazene...) in a continuous ceramic phase, with covalent interphase bonding (Si-O-M, P-O-M), could give rise to an increasing type of composite. However, in the classical sol-gel approach, the kinetics of the hydrolysis and condensation reactions are highly sensitive to the nature of the precursor, and this may be detrimental to a uniform dispersion. Thus in the case of polysiloxane Si-O-Si and M-O-M bonds are favored over Si-O-M ones. With polyphosphazenes, another problem arises from the following decomposition reaction: OH H  O --N=P--    --N--P--     H3PO4 + NH3
In this work, we explored a non-hydrolytic sol-gel method based on the heterocondensation of halide and alkoxide functional groups, with elimination of an alkyl halide at about 100ºC. This route was used to incorporate (CH3)2SiO units within metal oxide matrices. Solid-state 29Si MAS NMR spectroscopy showed evidence for Si-O-M bonds (M= Al, Ti, Zr). These data provide a tool for the further structural investigation of polysiloxane-based composites. The non-hydrolytic route made also possible the incorporation of cyclotriphosphazenes in TiO2 by the reaction of (NP(OR)2)3 with TiCl4. This opens a route to composites with polyphosphazenes covalently bonded to an oxide host matrix. 

Chairs: Thomas Bein and Ulrich Schubert 
Tuesday Morning, April 14, 1998 
Golden Gate A2
8:30 AM *O3.1 
USING INTERFACES, NON-EQUILIBRIUM AND MULTIPROCESSES IN THE MOLECULAR DESIGN AND SYNTHESIS OF MATERIALS. G.D. Stucky, D. Zhao, J.L. Feng, S.H. Tolbert, Q. Huo, P.Feng, and X. Bu, UCSB, Depts of Chemistry and Materials; B.F. Chmelka, S. Christiansen, A. Firouzi, M.T. Janicke, N. Melosh, and S. Williams, Department of Chemical Engineering; University of California, Santa Barbara, CA. 

This talk will present an overview on the use of some of the features of biogenesis, in particular kinetic control, competing processes, equilibria phenomena, multiphase media and the organic/inorganic interface, to synthesize composite materials that have patterned structural and physical properties from nanometer to macroscale dimensions.