Bio-based high-thermal-conductivity non-isocyanate polyurethane composites with flame-retardant and self-healing capabilities: design and performance regulation

Thermally conductive composites are witnessing expanding applications in electronics, energy and aerospace sectors. However, the development of eco-friendly, durable and high-performance thermally conductive materials remains a key challenge. To address this challenge, we rationally designed and fabricated a cardanol-derived non-isocyanate polyurethane (NIPU). Boron nitride nanosheets (BNNSs) and diphenyl chlorophosphate (DCP) were incorporated into the NIPU matrix to improve its thermal conductivity and flame-retardant performance. Moreover, dynamic disulfide bonds were rationally incorporated into the system, endowing the NIPU composites with efficient and reliable self-healing capabilities. Consequently, benefiting from the continuous thermally conductive pathways established by BNNSs, the 20% NIPU-2 N sample exhibited a striking 270% enhancement in through-plane thermal conductivity at a BNNSs loading of 20 wt%, reaching a final thermal conductivity of 1 W·m −1 ·K −1 . Additionally, the 20% NIPU-2 N achieved efficient self-healing at 100 °C within 3 h, with a tensile-strength recovery of 95.5%, and attained a V-0 flame retardancy rating. This fabrication strategy, leveraging the nano-reinforcing effect of BNNSs, offers a scalable approach that integrates green synthesis, efficient thermal management, and prolonged service life, demonstrating outstanding application potential in flexible printed circuits and wearable sensors.