Reactive molecular dynamics simulations on the hotspot formation and pyrolysis mechanisms of the TNBI/TANPDO cocrystal: effects of defects with different nano-void sizes†

The effects of void defect sizes on the hotspot formation and pyrolysis mechanism of the high-energy cocrystal 4,40,5,50-tetranitro-2,20-bi-1H-imidazole/2,4,6-triamino-5-nitropyrimidine-1,3-dioxide (TNBI/TANPDO) were quantitatively assessed by ReaxFF-lg molecular dynamics simulations. Nanosized defects can boost the enhancement of temperature in the surrounding localized regions, generating hotspots in the defective areas and triggering pyrolysis reactions. The formation of larger voids results in the generation of more intense hotspots, which in turn leads to the occurrence of more violent chemical reactions and the production of a greater number of reaction products in a shorter period of time. The decomposition rates of the components TNBI and TANPD vary with the temperature and defect size. The activation energies of defective crystals are lower, reflecting their higher sensitivity. These discoveries may offer a valuable reference for the development of new cocrystal explosives.