One-pot fabrication of an anisotropic thermally conductive boron nitride/polyvinyl alcohol composite film based on salting-out effect

The directional arrangement of thermally conductive lamellar fillers is an effective way to improve the thermal conductivity of polymer composites, which is achieved by the pre-construction of the thermal conductive network in most of the current research. Simplifying the process of the lamellar fillers' directional arrangement is significant for practical application, and a novel and facile fabricating method is reported in this study. First, the amino hexagonal boron nitride (BNNH2) was mixed with polyvinyl alcohol (PVA) water solution to prepare PVA/BNNH2 mixture. Subsequently, the mixture was dropped on the saturated sodium sulfate solution to obtain PVA/BNNH2 film through the salting-out function of PVA. The in-plane thermal conductivity of the as-prepared PVA/BNNH2 film can reach 3.09 W m(-1) K-1 with 30 wt% filler content. Furthermore, the PVA/BNNH2 films present excellent flexibility and good insulation. This paper may provide a new strategy for fabricating anisotropic thermally conductive polymer composites.