Highly Thermally Conductive Polyimide Composite Films with Excellent Thermal and Electrical Insulating Properties

Multifunctional polymer composites with high thermal conductivity are beneficial as thermal management materials for advanced electronics and technologies because of their design flexibility. However, conventional polymer composites do not possess all of the desirable material properties. Here, using the binary fillers graphene oxide (GO) nanosheets and hexagonal boron nitride (BN) platelets, we fabricated flexible polyimide (PI) composite films with high thermal conductivity and excellent thermal and electrical insulating properties. For the resultant PI composite films, a maximum thermal conductivity of 11.203 W/(m K) was achieved at a low filler loading of 1 wt % GO and 20 wt % BN, approximately 50 times higher than that of neat PI films. Theoretical models demonstrated that this synergistic enhancement resulted from the interactions of the binary fillers. The PI composite films also showed improved thermal mechanical properties and thermal stability and retained electrical insulation, moderate dielectric permittivity, and low dielectric loss.