Highly thermoconductive and mechanically robust boron nitride/aramid composite dielectric films from non-covalent interfacial engineering

Two-dimensional (2D) boron nitride nanosheets (BNNS), with exceptional thermoconductive properties and wide band gap, hold a great promise as candidate fillers for the preparation of the functional dielectric composites. However, the unsatisfactory dispersity in solvents and poor interfacial compatibility with the polymer matrix are still a great baffle for its practical applications. In the present study, we show that non-covalent functionalization of BNNS via polyvinylpyrrolidone (PVP) is a facile approach to optimizing their surface characteristics and facilitating the preparation of hybrid composites. The PVP functionalized BNNS (BNNS@PVP) can be dispersed stably in the aqueous solution for over 2 weeks. Composite films with ultrahigh thermal conductivity (similar to 14.5 W m(-1) K-1) are achieved solely by mixing with BNNS@PVP and one-dimensional (1D) aramid nanofibers (ANFs). Additionally, strong interfacial interactions are constructed between BNNS@PVP and ANFs, which further enables efficient stress transfer and charge dissipation through the 1D/2D configuration, contributing to outstanding tensile strength (similar to 184 MPa) and high electric breakdown strength (similar to 274 kV mm(-1)) for composite films. All these results demonstrate that surface modification of BNNS is a powerful tool for developing functional materials with multipurpose applications, including thermal management and high-voltage insulation.