Highly thermally conductive SiO2-coated NFC/BNNS hybrid films with water resistance

Abstract The miniaturization, integration, and lightweight of modern electronics have posed serious challenges to the development of high-performance and multifunctional thermal management materials. Here, we reported SiO2-coated nanofibrillated cellulose (NFC)/boron nitride nanosheets (BNNS) hybrid films with excellent thermal conductivity (TC) and hydrophobicity. These films were easily constructed via vacuum-assisted filtration and subsequent hydrophobic coating. The hybrid films exhibit a well-defined aligned structure with in-plane oriented BNNS. This finding was proven via wide-angle and small-angle X-ray scattering techniques, allowing for a high TC of up to 10.88 W m−1 K−1 at a low BNNS content of 7 wt%. Moreover, the hydrophobic hybrid films achieve high tensile strength (166.47 MPa) and electrical insulating property (volume resistivity = 1.2 × 1012 Ω cm). Inspired by the lotus effect, the water contact angle of such hydrophobic hybrid films reaches 143°, showing great potential in real applications for preventing the adverse effects of water and moisture.