Physical property and interface binding energy calculation of polyimide/boron nitride nanosheets thermally conductive composite insulating materials

As an insulating material, polyimide (PI) has low intrinsic thermal conductivity and high dielectric constant under high temperature conditions, which causes surface charge accumulation and severely limits the performance of insulation. In this paper, by adapting two-dimensional boron nitride nanosheets (BNNSs), a new type of material model with a PI-BNNS composite structure was established based on a molecular dynamics (MD) simulation method. Meanwhile, the thermal parameter, mechanical parameters, and electrical parameters of models with different doping concentrations at different temperatures were calculated. The results showed that the filling of BNNSs significantly improved the comprehensive performance by changing dielectric constant, breakdown field strength, thermal conductivity and so on. Furthermore, to reveal the microcosmic mechanism of the doping effect, the interfacial interaction intensity was analyzed by calculating the surface binding energy between PI/BNNS. With increasing doping ratio, the van der Waals interaction significantly increased, thus improving the phonon transfer capacity from electron movement to lattice vibration, leading to the mechanical properties and thermal conductivity of the materials significantly improved with increasing doping ratio. The increase in surface binding energy also leads to a deeper trap to capture the charge and produces charge shielding layers to improve the breakdown strength of the system.