Thermosetting self-healing HTPB binders with dual dynamic bonds for high-performance solid propellants

Traditional thermosetting hydroxyl-terminated polybutadiene (HTPB) binders are widely used in solid propellants for their excellent mechanical properties and chemical stability; however, they lack self-healing capabilities, leading to challenges in long-term reliability and damage repair under operational stress. To address these limitations, we developed a series of self-healable HPy-SS binders by incorporating synergistic dynamic hydrogen bonds and disulfide bonds through molecular design and formulated solid propellants with 80% solid content (ammonium perchlorate/aluminum powder) based on these binders. The HPy-SS binders were facilely synthesized with systematic adjustments to the disulfide/urea hydrogen bond ratio. The optimized HPy-SS3 binder exhibited a remarkable tensile strength self-healing efficiency of 96.1% at 60 °C over 48 h, coupled with superior thermal stability and enhanced chain segment mobility. The resulting propellants demonstrated thermal decomposition profiles and burning rates comparable to those made up from conventional HTPB counterparts, achieving a tensile strength self-healing efficiency of approximately 85.5% while maintaining thermoset structural integrity. This work offers a promising strategy for simultaneously improving the durability and repairability of solid propellants, with potential applications in advanced aerospace materials.