Desensitization mechanism and multiscale performance characterization of CL-20 with polydopamine coating

A polydopamine (PDA) coating strategy was developed to achieve desensitization of CL-20 and to elucidate its multiscale mechanism. The structure, thermal behavior, and macroscopic reactivity were systematically investigated. SEM and TEM confirmed the formation of a uniform PDA shell and a stable core–shell morphology, while XRD showed that the coating did not alter the intrinsic crystal form of CL-20. Differential scanning calorimetry revealed that the apparent activation energy increased from 152.27 to 226.06 kJ·mol⁻¹ , indicating enhanced thermal stability. Closed-bomb tests showed a 29.1% reduction in peak pressure and a 34.5% decrease in pressurization rate, confirming moderated decomposition kinetics. At the PBX formulation level, the 5 s deflagration point increased from 273.6 °C to 291.7 °C, reflecting a 6.6% improvement in thermal safety. In fast cook-off tests, the uncoated CL-20 PBX underwent violent explosion, while the coated CL-20@PDA PBX exhibited a transition to controlled combustion with significantly lower overpressure and reaction violence. Under slow cook-off conditions, both PBXs showed combustion behavior, but the coated formulation produced a milder reaction and reduced overpressure. These results demonstrate that the PDA layer acts as a physical and thermal barrier that suppresses hotspot formation and retards heat transfer. The study provides quantitative evidence for the desensitization mechanism of CL-20 and establishes a multiscale framework for designing safer high-energy materials.