Polyurethane-templated 3D BN network for enhanced thermally conductive property of epoxy composites

Utilizing three-dimensional filler has been deem as a promising approach to improve the thermal conductivity of polymer composites. In this research, we developed a polyurethane sacrificial template technique to fabricate a novel three-dimensional porous carbon bonded BN foam (3D-CBNF), aiming to improve the thermal performance of polymers (epoxy). The as-prepared 3D-CBNF/epoxy composite exhibits a high thermal conductivity (TC) of 2.11 Wm−1K−1 at a relatively low BN loading of 24.7 wt%, corresponding to a TC enhancement (TCE) of 1072% compared with the pure epoxy resin. The analysis of the thermal conductivity mechanism based on EMT and Foygel models and finite element simulation indicated that the high thermal conductivity of composites was due to the efficient heat transfer pathways provided by the 3D interconnected BN network and lower interface thermal resistance in internal of it. In addition, the as-obtained composite possessed a relatively low dielectric constant (below 4.5 at 1 MHz) and a high volume electrical resistivity (beyond 1015 Ω·cm). Overall, a novel and promising method of preparation for 3D construction with thermally conductive filler, which is designed to attain composites with high thermal conductivity, has been proposed in this work.