Effects of Functionalization and Aspect Ratio of Graphene on Thermal Conductivities of Graphene/epoxy Composites

The effect of functionalization on thermal conductivities of graphene embedded in epoxy and its composites is studied using molecular dynamics simulations. The surrounding epoxy matrix reduces the thermal conductivity of graphene itself by 50 %, making it less efficient in improving the thermal conductivities of composites. The chemical modifications of graphene with different functional groups much reduce its intrinsic thermal conductivity, while they improve the interface thermal conductance between the functionalized graphene and epoxy. It is revealed that triethylenetetramine (TETA) functionalized graphene oxide (T-GO) is the most efficient in improving the thermal conductivities of composites among a few different graphene with and without functionalization. The covalent bonds and the ability of long chain of TETA to penetrate into the epoxy molecules facilitate the phonon coupling between T-GO and epoxy, which contribute to the enhanced interface thermal conductance and thus the thermal conductivities of the composites.