Molecular dynamics simulation of CL-20/1,4-DNI cocrystal PBXs

The CL-20/1,4-DNI cocrystal is a novel high explosive with exceptional energy density and detonation parameters. However, in comparison with insensitive explosives including TNT and TATB, it still retains a relatively high level of sensitivity. To mitigate the sensitivity of the CL-20/1,4-DNI cocrystal explosive, this study constructed a molecular model of the CL-20/1,4-DNI cocrystal, and then separately incorporated five distinct classes of polymers-butadiene rubber (BR), ethylene-vinyl acetate copolymer (EVA), polyethylene glycol (PEG), fluoropolymer (F2603), and polyvinylidene fluoride (PVDF)-onto its four most probable crystal planes, namely (1 0 1), (0 0 2), (0 1 1), and (1 1 0), a series of polymer-bonded explosives (PBXs) were thereby fabricated, and the influence of varying polymer matrices on the resulting materials-including their stability, trigger bond length, mechanical properties, and detonation performance-was systematically predicted and evaluated. Among the five developed PBX models, the CL-20/1,4-DNI/PEG composite attained the highest binding energy and the shortest trigger bond length. These outcomes demonstrate that the CL-20/1,4-DNI/PEG system possesses optimal stability, compatibility, and minimal sensitivity. Additionally, while the CL-20/1,4-DNI/F2603 composite exhibited superior detonation initiation capability, of note is that the compatibility of this particular formulation was relatively low. Consequently, the CL-20/1,4-DNI/PEG composite, which demonstrates an optimal stability-performance balance, emerges as the definitive choice, highlighting PEG as the preferred binder for CL-20/1,4-DNI-derived PBXs.

Utilizing the molecular dynamics (MD) framework implemented in Materials Studio, the relevant functions embedded in the Forcite module were employed for the calculations; the performance of CL-20/1,4-DNI-based PBXs was evaluated. The simulation parameters were configured to a time step of 1 fs and a cumulative run time of 2 ns. The isothermal-isobaric (NPT) ensemble was employed for the 2-ns MD simulations. The COMPASS force field was adopted, and the simulation temperature was fixed at 295 Kelvin (K).