Initial Decay Mechanism of the Heated CL-20/HMX Cocrystal: A Case of the Cocrystal Mediating the Thermal Stability of the Two Pure Components

Abstract

Energetic cocrystallization, by combining existing molecules together, is thought to be new strategy for creating energetic materials. Nevertheless, the underlying mechanism of its influences on properties and performances in comparison with their pure components remains unclear. The present work reveals the cocrystallization influence of a typical energetic cocrystal of CL-20/HMX on thermal stability, by ReaxFF molecular reactive dynamic simulations and kinetics calculations on the pure and cocrystals. As a result, we find that the cocrystal mediates the thermal stability of pure crystalsand this is in agreement with experimental observations. The initial decay steps in pure crystals remain still in the cocrystal, that is, the independent and intramolecular reactions of N–N bond cleavage governing the initial decay of the pure CL-20 and HMX crystals also dominate in the cocrystal of CL-20/HMX. Meanwhile, during the thermal decomposition of the cocrystal, CL-20 releases heat faster than HMX, thus the heat...