The construction of heat transfer channels based on highly thermally conductive fillers in polymer matrix are important for improving the thermal conductivity of thermal management materials (TMM). However, due to the inhomogeneity of the filler distribution and the limitation of the mechanical properties of polymer, it is a great challenge to achieve both high thermal conductivity and excellent mechanical properties. In this work, a simple air/water interfacial (AWI) assembly was implemented for the preparation of boron nitride-silver nanowires/polyvinyl alcohol films (BN-Ag NWs/PVA). Firstly, BN-Ag NWs hybrid fillers were obtained by the ultrasonic treatment of amino-functionalized BN flakes with Ag NWs solution, followed by drying. BN-Ag NWs/PVA composite films were prepared by AWI assembly on the surface of saturated sodium sulphate solution based on the salting-out effect. BN flakes tended to be oriented and aligned along the in-plane direction, and Ag NWs could bridge different BN flakes to form thermal conductivity pathways. The in-plane thermal conductivity of BN-Ag NWs/PVA film was 1.24 W·m-1·K-1 at 25 wt% filler content, which was about 4.8 times higher than that of the pure PVA film. Meanwhile, the tensile strength of BN-Ag NWs/PVA film could reach 54.3 MPa due to the regular distribution of hybrid fillers. The joint improvement of thermal conductivity and mechanical properties was beneficial for the practical application of BN-Ag NWs/PVA film.

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