Robust PU foam skeleton coated with hydroxylated BN as PVA thermal conductivity filler via microwave-assisted curing

To achieve adaptation to the heat dissipation effect of electronic devices in the 5G era and improvement of the anisotropic thermal conductivity of the insulating polymer, three-dimensional (3D) PU@BNNS-OH network structure was constructed via layer-by-layer assembly with polyurethane (PU) foam as the robust skeleton of three-dimensional structure, and hydroxylated boron nitride nanosheet (BNNS-OH) as thermal conductive filler. Then PU@BNNS-OH was composited with polyvinyl alcohol (PVA) via microwave-assisted curing method to get the final thermal conductivity composites (PVA/PU@BNNS-OH). The result showed that the interconnected thermal conductivity network was significantly effective in improving the anisotropic thermal conductivity of the composite with high-temperature endurance and moderate mechanical property. When the BNNS-OH coating is 10 wt%, the optimal thermal conductivity of the composite is 4.68 W · \({\mathrm{m}}^{-1}\) · \({\mathrm{K}}^{-1}\) and the thermal conductivity enhancement efficiency is 45.50, which is significantly higher than others reported in the literature. Both the finite element analysis and thermal infrared analysis indicated that the thermal conductivity of the composites was significantly improved and paved the way for its potential application. The present microwave-assisted synthesis strategy is fast and energy-saving and can be widely used for synthesizing different insulated polymer-based thermal interface materials.