Dynamic molecular simulation for CL-20/3,5-MDNP(1-methyl-3,5-dinitropyrazole) co-crystal PBX explosives

The 2:1 CL-20/3,5-MDNP co-crystal explosive represents a novel energetic material with outstanding energy density and detonation characteristics, regarded as a promising candidate to replace RDX. Nevertheless, it still exhibits relatively high sensitivity As contrasted with insensitive high explosives such as TATB. To abate the sensitivity of the 2:1 CL-20/3,5-MDNP co-crystal explosive, a theoretical model of the 2:1 CL-20/3,5-MDNP co-crystal was constructed in this work. Five distinct polymers, including BR (polybutadiene rubber), EVA (ethylene-vinyl acetate copolymer), PEG (polyethylene glycol), F2603, and PVDF (polyvinylidene fluoride), were separately deposited onto five crystallographic surfaces: (0 -1 1), (0 -2 0), (0 0 1), (0 1 1), and (0 2 0), yielding a series of PBXs. The influences of these polymeric binders on the structural stability, trigger bond length, mechanical properties, and detonation performance of the associated PBX systems were anticipated by means of theoretical evaluations. Amidst the five PBX constructs, the CL-20/3,5-MDNP/EVA system possesses the highest binding energy, indicative of superior structural stability, interfacial compatibility, and reduced sensitivity. In contrast, while the CL-20/3,5-MDNP/PEG formulation exhibits superior initiation characteristics, it is noted to display relatively weak interfacial compatibility.In summary, the CL-20/3,5-MDNP/EVA system is recommended for applications prioritizing high stability and strong compatibility, whereas the CL-20/3,5-MDNP/PEG system is more suitable for scenarios demanding enhanced detonation performance.

Within the Materials Studio software environment, the properties of 2:1 CL-20/3,5-MDNP co-crystal-based PBXs were predicted using molecular dynamics (MD) simulations. The MD simulation time step was set to 1 fs, with a total simulation duration of 2 ns. The isothermal-isobaric (NPT) ensemble was employed throughout the 2-ns MD run. The COMPASS force field was adopted, and the system temperature was maintained at 298 K.