Enhanced thermal conductivity and fire safety of flexible hybrid film via synergistic effects between boron nitride and functionalized graphene

Polymers present typically low thermal conductivity (TC) and potential fire hazards and thus restricted its application in electronics. Here, graphene oxide (GO) was employed to replace the traditional synthetic polymers. Then, the vacuum-assisted self-assembly technique was developed to prepare multifunctional flexible hybrid film based on synergistic effect of functionalized GO (PGO) and boron nitride nanosheets (BNNS). Results show that a "nacre structure" can be observed and a superior interface between matrix and fillers was constructed. Thus, the films possess high in-plane TC of 30.44 W m(-1) K-1, as well as excellent flexibility. The high TC is ascribed to constructing of the hydrogen bonding between BNNS and PGO to form a well-designed BNNS-PGO interface. Another contribution is that the dispersion of BNNS was enhanced and formed continuous TC paths. Furthermore, as-prepared hybrid films possess excellent flame retardancy and the total heat release rate and peak heat release were dropped by 75.4% and 72%, respectively, compared with original GO. Fire experiment shows that the alarm lamp and alarm buzzer connected with the hybrid film will send out the alerts within 2 s to people for taking emergency actions. This nanocomposite presents great potential applications in next-generation intelligent electronic equipment.