Dynamic poly(oxime-urethane) networks reinforced by copper coordination for mechanically robust, self-healing and reprocessable energetic composites

Crosslinked polyurethane adhesives are essential for maintaining the structural integrity of composite propellants, but the irreversible crosslinked networks impede the restoration of mechanical properties and the reprocessability of aged or damaged composite propellants. Herein, we report a dynamic poly(oxime-urethane) (POU) adhesive that integrates reversible oxime-urethane linkages with copper-coordination reinforcement for self-healing and reprocessable energetic polymer composites. Frontier molecular orbital (FMO) calculations were used to elucidate the dynamic reactivity of oxime-urethane bonds and guide the molecular design of POU networks. As a result, a series of POU binders were synthesized, exhibiting improved mechanical properties and superior self-healing capability compared with conventional PU binders. In addition, the addition of CuO nanoparticles into the POU system induced copper coordination with oxime-urethane moieties, affording a resin possessing 1.4-fold higher tensile strength and 2.0-fold greater toughness compared to the pristine POU resin. Hot-pressing of the copper-coordinated POU resin nearly restored the original tensile properties, demonstrating its outstanding reprocessability and self-healing capability. Furthermore, the application of copper-coordinated POU adhesives in Al/AP/HTPE composite propellants not only enabled efficient self-healing but also improved combustion performance. The synergistic integration of reversible oxime-urethane bonds and dynamic copper coordination establishes an effective binder design strategy for property recovery and reprocessing of aged or damaged energetic composites, providing new opportunities for durable and repairable composite propellant systems.