Improve safety performance and thermal stability: preparation and characterization of core–shell structure CL-20-P@PANI

To enhance the safety performance and thermal stability of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexazepane (CL-20), a core–shell composite was synthesized via in situ polymerization of aniline on polyethyleneimine (PEI)-modified CL-20. PEI modification introduced –NH 2 groups onto CL-20 surface, providing active sites for aniline polymerization and inhibiting its self-polymerization, thus forming dense polyaniline (PANI) shells with uniform thickness (about 2.8 mass%) while maintaining the high-energy crystal structure of CL-20. Compared to pure CL-20, CL-20-P@PANI showed a 15.8 °C increase in phase transition temperature (185.5 °C) and a 4 °C rise in thermal decomposition temperature (247.21 °C), attributed to the thermal barrier effect of PANI shells. The results of the mechanical sensitivity test indicate that the dense polyaniline shell layer effectively dissipates external forces, leading to a 51.43% reduction in impact sensitivity and a 20% decrease in friction sensitivity. This study provides a novel modification approach for high-energy materials by combining PEI-mediated interface engineering with in situ polymerization, ensuring both safety and energy characteristics. Graphic abstract