Abstract: Hydroxyl-terminated polybutadiene (HTPB)-based solid propellants using ammonium perchlorate (AP) as the oxidizer are widely used in solid rocket motors. However, the inferior defects of AP, such as high thermal decomposition initiation temperature and low high-temperature decomposition rate, limits propellant combustion performance. Conventional combustion catalysts exhibit insufficient catalytic activity, elevated pressure exponent, and inability to concurrently inhibit ultrafine AP agglomeration and mitigate its hygroscopicity. Thus, their adoption in high-reliability, production-ready propellant formulations remains limited. This work investigates the thermal decomposition of AP using Fe-based functional coordination polymer energetic composites (Fe-CPs@AP). Propellants containing 4% (in mass) Fe-CPs@AP show enhanced combustion performance, with burning rates increasing by 56%-76% over the baseline propellant. The pressure exponent is 0.571, significantly lower than that of conventional catalyzed systems (typically>0.7). This improvement results from optimized interfacial interactions between Fe-CPs@AP and the propellant matrix, promoting the in situ formation of uniformly dispersed metal oxide nanoparticles during AP decomposition and maximizing catalytic activity. Mechanistic and density functional theory studies indicate that Fe-containing species serve as catalytic mediators. They enhance electron transport in the low-temperature decomposition phase, optimize electron transfer between ClO₄^- and NH₄⁺, promote oxygen species adsorption, increase thermal energy release at high temperatures, and improve AP decomposition efficiency. This work tackles issues such as AP’s hygroscopicity, particle aggregation, and pressure sensitivity, offering theoretical and practical support for developing high-performance combustion propellants.

Key words: Fe-based functional coordination polymer, AP-HTPB propellant, combustion catalyst, decomposition of AP