ReaxFF MD simulations of thermolysis mechanism of 2, 6-diamino-3, 5-dinitropyrazine-1-oxidated

As one of the important high energetic insensitive explosives, LLM-105 has attracted considerably attention. In this work, the thermal decomposition of LLM-105 was analyzed at 2000, 2250, 2500, 2750, 3000, 3250, and 3500 K. Reaction times were controlled to be 200 ps. The results showed that the main small molecule products in this reaction stage were H2O, N-2, CO2, and H-2. At low temperatures, water molecules form earlier than nitrogen ones, while the opposite is found at high temperatures. In the initial stage of the reaction, LLM-105 often undergoes a large amount of intermolecular H-transfer and dimerization, and this phenomenon is significantly reduced as the temperature rises. On the other hand, LLM-105 itself is very easy to polymerize to form clusters, and its cyclic structure is more likely to form a macromolecular cluster by diverse linkages (e.g. C-N-N-C). As the reaction progresses, the atoms of H, O, and N gradually escape from the cluster structure, but most of the oxygen atoms stay stable. The activation energy of the initial decomposition reaction of LLM-105 is 167.9 kJ/mol, which is in a reasonable range.