Alumina-coated graphene sheet hybrids for electrically insulating polymer composites with high thermal conductivity

Graphene has attracted considerable attention as a promising candidate to improve the thermal conductivity of polymers owing to its extremely high intrinsic thermal conductivity (∼5300 W m−1 K). However, graphene-based composites show a high electrical conductivity even with a low loading of fillers, which greatly limits their applications in electronic devices. Herein, we present a new class of fillers of alumina-coated graphene sheet (GS@Al2O3) hybrid fillers via an electrostatic self-assembly route. This unique structural design combines the advantages of both the GS and Al2O3, resulting in PVDF/GS@Al2O3 composites that show not only high thermal conductivity, but also retain high electrical insulation. For instance, the thermal conductivity of PVDF composites with 40 wt% GS@Al2O3 is up to 0.586 W m−1 K and the volume resistivity is above 4 × 1014 Ω cm. Moreover, this self-assembly route is a simple and scalable strategy for fabricating high performance thermally conductive materials.