Stable self-crosslinking phase change composites with vertically aligned boron nitride for high thermal conductivity thermal interface materials

Thermal interface materials (TIMs) must have a high through-plane thermal conductivity in order to efficiently transfer the heat generated by electronic components to heat sinks. Nevertheless, the achievement of high through-plane thermal conductivity is still a great challenge due to the inadequate thermal conductivity network as well as the lack of thermal response from the polymer matrix. Herein, we have developed a solid-solid phase change polymer matrix achieved through self-crosslinking polyethylene glycol (SCPEG). Subsequently, high-performance TIMs based on the SCPEG matrix and vertically aligned boron nitride (BN) nanosheets are obtained by bidirectional freezing, hot pressing, and longitudinal slicing. The prepared BN/SCPEG composites (BN content of 80 vol%) with a vertically oriented network achieved a through-plane thermal conductivity of 23.03 W m-1 K-1. More importantly, the vertically aligned BN nanosheets improve the thermal conductivity of composites, while the SCPEG matrix can reduce the hardness of composites by absorbing the heat, thus decreasing the contact thermal resistance.