(819a) Invited Talk: Graphene Without Compromise: Dispersion, Processing, Morphology, and Composites
One of the chief research needs for the polymer processing community is the ability to construct nanocomposites with targeted properties at low filler content. The versatility and extraordinary properties of graphene, i.e., single-layer graphite sheets, shows promise for meeting these needs. Here we discuss the central concept of producing graphene from graphite without covalently functionalizing the graphene basal plane; such graphene may be stabilized, dispersed, and processed for use in a range of high-performance materials, including polymer composites, fibers, and gels. In particular, our group has shown that both polyvinylpyrrolidone as well as pyrene derivatives can naturally absorb to the graphene surface, create repulsive (steric and electrostatic) forces, and prevent aggregation. This allows for graphene dispersion in a wide range of organic solvents and composite precursors without compromising graphene structure. Such dispersions are stable against aggregation even when subjected to extreme temperature changes, pH changes, and freeze drying. Polymer nanocomposites formed from these dispersions (graphene-loaded epoxy, graphene-loaded polyvinyl alcohol films and nanofibers, graphene-polymer hydrogels and aerogels) consistently show enhanced modulus, strength, and electrical conductivity. Dispersion quality may be characterized in both the solution state as well as the final composite state using percolation-based metrics.