Effectively decoupling electrical and thermal conductivity of polymer composites

Hybrid nanocrystals, fullerene-decorated graphene, were incorporated into the epoxy composites, and their electrical and thermal transport was investigated. The hybrid nanocrystals were fabricated through a solution process and the resultant hybrid nanostructure was verified by transmission electron microscopy and X-ray diffraction characterization. After incorporation of fullerene-functionalized graphene into epoxy resin, the electrical conductivity increased significantly while the thermal conductivity only increased slightly, resulting in effectively decoupling thermal/electrical conductivity. Through filling fullerene/graphene nanohybrids into the epoxy resins, the electrical conductivity was increased from 10−14 to 2949 S/m, more than 17 orders of magnitude. On the other hand, the thermal conductivity was only increased from 0.3 to 0.66 W mK, only two-fold increments. Further theoretical calculations and comparative experiments indicated that the synergistic effects of graphene and fullerene nanocrystals resulted in the effective decoupling of thermal/electrical transport. The electrical transport was improved through graphene sheets while the lattice thermal transport was impeded through fullerene decorated on the graphene sheets. The de-coupling of electrical and thermal conductivity of polymer composites opens numerous opportunities for new materials and systems.