Intercalated Two-Dimensional Ceramic Nanocomposites
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INTERCALATED TWO-DIMENSIONAL CERAMIC NANOCOKPOSITES
E.P. GIANNELIS, V. 4EHROTRA, 0. TSE, R.A. VAIA, AND T.-C. SUNG Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
ABSTRACT New generations of polymer-ceramic nanocomposites are being developed by intercalation of layered solids. Synthetic approaches include intercalative polymerization, direct polymer intercalation and molecular dispersion of the host layers in the polymer matrix. The unique physical and mechanical properties of the hybrids are attributed to the molecular dispersion and the synergism between the individual components.
INTRODUCTION Materials Desig As requirements for high technology applications become more demanding so does the need for developing new materials. Ideally, actual synthesis and characterization must be successfully integrated with the molecular and microstructural design. Thus, new revolutionary design principles and processing approaches that allow control at the molecular level are required. This paper reviews our efforts to develop a new generation of polymer-ceramic nanocomposites using intercalation of layered ceramics [1-3] as illustrated in Figure 1. Our approach is based on the ability of layered solids to ingest (intercalate) a wide variety of chemicals in the gaps (galleries) formed between the layers. The whole thrust of producing novel composites materials by intercalation of layered ceramics, as opposed to those with the properties of a simple mixture of the components, as shown in Figure 2, is that the molecular features and the apparent synergism in the former could impart unique properties not necessarily limited by the rule of mixtures. Therefore, new composites can be designed that combine the overriding strength, dimensional and thermal stability of ceramics with the fracture properties, processability and dielectric properties of polymers. This new approach exploits the tendency of the layers in a lamellar solids to organize like a deck of cards, i.e. the layers tend to be organized in the c direction but not necessarily in the a and b axes of individual layers. The self-assembling property of the host is instrumental in organizing literally hundred of thousands of layers in a single processing step with a high degree of ordering. It also distinguishes intercalation from the Langmuir-Blodgett technique where a laborious layer-by-layer deposition is required. Selfassembling components have been used for millions of years by biological organisms to build multifunctional materials with complex structures at many spatial levels [4]. Examples range from strong and tough composites to highly selective sensing membranes.
Mat. Res. Soc. Symp. Proc. Vol. 249. @1992 Materials Research Society
548
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