Significant Enhancement of Thermal Conductivity in Bioinspired Freestanding Boron Nitride Papers Filled with Graphene Oxide

Owing to the miniaturization of power electronics and the development of portable and flexible devices, demands for highly thermally conductive, mechanically flexible, and electrically insulating composites have substantially increased. However, the conventional method to improve thermal conductivity usually yields both an undesired value (usually below 10 W m^–1 K^–1) and poor flexibility. Thus, a combination of all the desired properties together remains a technical challenge. Bioinspired engineering offers great promise in the synthesis and fabrication of thermal materials that are different from engineering through conventional approaches. Inspired by the interface and orientation of natural nacre, we report on thermally conductive and mechanically flexible papers based on boron nitride nanosheets (BNNSs) and graphene oxide (GO) via a simple vacuum-assisted filtration process. We experimentally show that the papers possess high thermal conductivity of 29.8 W m^–1 K^–1, excellent mechanical flexibility, and satisfactory electrical insulation. We attribute the high thermal conductivity to the well-designed BNNS–GO interface as well as the advantageous orientation in layered structure. This approach to constructing thermally conductive composites provides a creative opportunity for design and fabrication of high-performance materials in the near future, and this kind of paper has great potential application in next-generation commercial portable electronics