Significant thermal conductivity enhancement of polymer nanocomposites at low content via graphene aerogel

• The rGO hydrogel was prepared by a simple oxidation–reduction process. • A low-density reduced graphene oxide aerogel was obtained by the hydrogel via vacuum freeze-dried. • The 3d-rGO/epoxy resin with a three-dimensional thermally conductive skeleton was obtained by impregnation. • An ultra-high thermal conductivity of 1.79 W/m·K was obtained at the low graphene content of only 1.8 vol%. Using ascorbic acid as the reducing agent, a three-dimensional skeleton reduced graphene oxide (rGO) aerogel is prepared. The epoxy resin composites with high thermal conductivity and low filling content are successfully prepared via vacuum impregnation method combining the graphene aerogel and epoxy. The results show that the 3D-rGO/epoxy composites exhibit superior thermal conductivity to the randomly dispersed graphene epoxy composites at the same content, e.g., the 3D-rGO/epoxy composite has a thermal conductivity of 1.79 W/m*K at 1.8 vol% rGO, compared to 0.77 W/m*K for the randomly dispersed rGO/epoxy composite. The strategy of graphene/epoxy composite in this work has a broad prospect as thermal interface materials (TIMs) in the field of electronic packaging.