Role of solvent in enhancement of thermal conductivity of epoxy/graphene nanocomposites.

Uniform dispersion of graphene nanoparticles into epoxy is critical for achieving high thermal conductivity epoxy-graphene nanocomposites. Uniform dispersion can reduce gap between graphene nanoparticles increasing the potential of direct contact between them, establishing thermal percolation, leading to higher thermal conductivity of the composite. Organic solvents typically lead to efficient dispersion of graphene into the epoxy matrix. In this study, we compare the effect of two organic solvents (dimethylformamide (DMF) and acetone) in terms of their efficiency in dispersing graphene into the epoxy matrix and their effect on enhancing thermal conductivity of the composite. While the effect of solvents on mechanical properties of polymer-graphene nanocomposites has been studied, an understanding of their effect on thermal conductivity is lacking. In this study we find that polymer-graphene composites made with DMF show 44% higher thermal conductivity than those made using acetone. Laser scanning confocal microscopy (LSCM) imaging reveals improved dispersion of graphene-nanoplatelets in samples prepared using DMF compared to acetone. These results provide new avenues to achieve higher thermal conductivity graphene-epoxy composites.