Differences in the Initial Thermal Decomposition Mechanisms of Isomeric Nitrogen-Rich Energetic Compounds: A First-Principles Study of DTDA and T-N10B.

As novel isomeric nitrogen-rich energetic materials (NREMs), 1,2-di(2'H-[1,5'-bitetrazol]-5-yl) diazene (DTDA) and 2,2'-azobis(1,5'-bitetrazole) (T-N10B) have attracted considerable attention due to their excellent detonation performance. In this study, first-principles molecular dynamics simulations were employed to systematically investigate the differences in their initial thermal decomposition mechanisms. Results show that both T-N10B and DTDA share three major initial decomposition pathways, but T-N10B tends to initiate via inner/outer tetrazole ring-opening, while DTDA prefers H atom dissociation and inner ring-opening. After initial decomposition, T-N10B releases large amounts of N2 in the subsequent two steps, whereas DTDA still undergoes extensive H atom dissociation/transfer, leading to less N2 release. Notably, both molecules have specific tetrazole ring-opening sites. Furthermore, the significant H-transfer reactions during the early stage and the better tetrazole ring stability are key to DTDA's superior thermal stability, making it decompose more slowly than T-N10B. These findings will deepen the understanding of the energy release mechanism of tetrazole-based NREMs and provide important insights for the design of novel NREMs.