Dual dynamic bonds self-healing polyurethane with superior mechanical properties over a wide temperature range

Polyurethane (PU), used as the adhesive of composite solid propellants, is prone to damage. Nowadays, self-healing capability has been regarded as the attractive solution. However, self-healing PU usually reveals unsatisfactory mechanical performances failing to meet the requirements of composite solid propellants. In this work, a feasible method was developed to achieve the adhesive with remarkable mechanical and self-healing characteristics by introducing dual dynamic bonds into hydroxyl-terminated polybutadiene (HTPB)-based PU. It exhibits a substantial efficiency of self-healing of about 93% for 2 h at 60 °C. Meanwhile, the self-healing efficiency is 74% when repairing for 6 h at 25 °C. Impressively, this material demonstrates significant mechanical properties, even over a wide temperature range. Its elongation at break at room temperature is up to 2706.8%. It exhibits 1447.9% and 1458.9% elongation at break at 70 °C and − 40 °C, respectively, significantly higher than that of HTPB. The present research represents an essential and achievable approach for the preparation of the high-performance self-healing composites propellant adhesive with outstanding high and low temperature mechanical properties.