Influence of polydopamine coating on the thermal stability of 2,6-diamino-3,5-dinitropyrazine-1-oxide explosive under different heating conditions

[Display omitted] •PDA-coated LLM-105 was synthesized and characterized for the first time.•The influence of PDA coating on the thermal stability of LLM-105 varies under different heating conditions.•Heat released amount of PDA and heat-transfer rates between the samples and environment regulate such effect. Polydopamine (PDA) surface coating is an effective way to improve the performance of energetic materials at present. In this study, after coating the surface of insensitive explosive 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) with PDA, the resulted LLM-105@PDA particles were subjected to in-depth characterizations and a compact core-shell formation with a dense graphite-like structure PDA on LLM-105 crystal was confirmed. The influence of PDA coating on the thermal stability of LLM-105 was studied under three typical heating conditions: programmed, constant-temperature, and adiabatic. Our results demonstrated that the PDA can hardly affect the thermal stability of LLM-105 under non-adiabatic conditions but remarkably intensified under adiabatic conditions. The amount of heat released by PDA decomposition and the heat-exchange rate between sample and environment are the key to this effect, which was confirmed by the Comsol numerical simulation. This work provides a novel perspective for evaluating the thermal stability of mixed explosives containing the functional additive with lower decomposition temperature.