Proceedings Published 2007 by the American Chemical Society POLYMER NANOCOMPOSITES WITH PRESCRIBED MORPHOLOGY: GOING BEYOND NANOPARTICLE-FILLED POLYMERS

Introduction Over the last decade, Polymer Nanocomposites (PNCs) have been one of the most extensively examined areas of polymeric nanomaterials. These efforts have lead to numerous commercial successes, innovative approaches for fabricating and tailoring hybrid materials, and important fundamental insights on the behavior of polymers in confined environments . Given the extensive variety of nanoparticles now commercially accessible (clays, carbon nanotubes, quantum dots, metals, silica, titania, zirconia, various oxides, etc..), the potential combinations of polymers and nanoparticles, and thus the tailorability of the property suite, is essentially endless. However, beyond maximization of the nanoparticle dispersion, the morphology of the vast majority of the polymer nanocomposites reported to date is uncontrolled, yielding isotropic nano-filled systems, not necessarily spatially ‘engineered, designed and tailored’ materials. Among the many challenges as PNCs move beyond commodity plastic applications, precise morphology control is paramount. Random arrangements of nanoparticles will not provide optimized electrical, thermal or optical performance for many potential high-tech applications, such as dielectric under-fills for electronic packaging, printed flexible electronics, engineered aerospace structural components, reconfigurable conductive adhesives and optical gratings to just mention a few. Two general approaches to this challenge of hierarchical morphology control are emerging, namely: externalin (directed patterning of nanoparticle dispersions) and internal-out (mesophase assembly of nanoparticles). Directed patterning of nanoparticle dispersions using external electric fields is discussed.