Solvent evaporation induced self-assembly of graphene foam for thermally conductive polymers†
Graphene, a new carbon material with the highest thermal conductivity (TC) in known materials, is a good candidate for polymer-based thermally conductive material applications. However, the homogeneous dispersion of graphene and effective construction of graphene-based thermally conductive network in the polymer matrix still remains a big challenge. In this paper, we report an effective way to avoid aggregation of graphene in polymers through the fabrication of 3D porous graphene foam (GF) in advance by a simple solvent evaporation induced self-assembly method. The as-prepared GF is proved to be an effective thermally conductive network after the epoxy perfusion, giving rise to a high TC of 11.58 W (m−1 K−1) for the GF/epoxy composite. In addition, anisotropic TC in the GF/epoxy composites is observed because of the oriented arrangement of graphene sheets in the GF due to solvent evaporation. Besides, further improvement of TC to 16.69 W (m−1 K−1) can be achieved by addition of polyvinyl pyrrolidone (PVP) during the preparation of GF, which can be ascribed to the reduction of interfacial thermal resistance by amorphous carbon generated from pyrolysis of PVP.