The impact of electronic effect on the dissociation mechanism of oxadiazole-based regioisomeric energetic materials

With the rapid development of synthesis methods for energetic materials, the regioisomerism effect is gaining increasing attention in the design of multifunctional energetic compounds and in the in-depth study of the relationship between structure and performance. Understanding regioisomerism in energetic materials and its impact on material performance can provide a theoretical basis for material improvement and design. In this paper, the influence of regioisomerism on the thermal stability of oxadiazole-based energetic materials 5,5′-bis(trinitromethyl)-3,3′-bi(1,2,4-oxadiazole) (BTBO) and trinitromethyl substituted β-bis(1,2,4-oxadiazole) (TSBO), which have a significant difference in the dissociation temperature, has been thoroughly investigated. The initial decomposition mechanism of the regioisomers is fully discussed, proving that the NO2-dissociation path is the main decomposition pathway, revealing that the difference in the energies of the main dissociative bonds of BTBO and TSBO is the direct cause of the different thermal stabilities. The regioisomerism on the thermal stability of BTBO and TSBO is investigated: the electronic effect increases the polarity and reduces the bond order of the main dissociative bond in BTBO, resulting in a lower dissociation temperature for BTBO.