▎ 摘　　要

Highly thermally conductive polymer composites are urgently required for effective heat dissipation in advanced electronic devices. Rational matching of thermal conductive fillers and proper preparation method are important for obtaining a highly thermally conductive composites at low filler content. Here we report polyimide (PI) composites filled with graphene flakes (GF) and polyhedral aluminum nitride (AlN), which simultaneously exhibit high thermal conductivity, improved thermal mechanical properties, and excellent thermal stability. PI composite films were readily prepared by in situ polymerization at the presence of fillers that are dispersed with sonication. The thermal conductivity of PI composite films reached 11.19 Wm(-1) K-1 at the low content of 1 wt% GF and 10 wt% AlN, which is ascribed to the construction of synergistically enhanced heat transfer pathways by the combination of the hybrid fillers. The PI composite films with hybrid fillers also showed lower electrical conductivity than that of the PI composite films with single GF filler. This study provides an effective method for preparation of high-performance thermal management materials.