Comparative studies on structure, sensitivity and mechanical properties of CL-20/DNDAP cocrystal and composite by molecular dynamics simulationElectronic supplementary information (ESI) available: Cell parameters of CL-20/DNDAP cocrystal at different temperatures, the balanced curves of CL-20/DNDAP cocrystal at 298 K and CED curves of CL-20/DNDAP cocrystal at different temperatures. See DOI: 10.1039/c8ra07387b

Molecular dynamics simulation was performed on 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), 2,4-dinitro-2,4-diazapentane (DNDAP), and CL-20/DNDAP cocrystal and composite under COMPASS force field at different temperatures. The binding energy ( E bind ), radial distribution function (RDF), trigger bond length, cohesive energy density (CED) and mechanical properties were studied and compared. The results show that the binding energy of the cocrystal is evidently higher than that of the composite at the same temperature. RDF analysis reveals that hydrogen bonds and vdW forces between CL-20 and DNDAP exist in both CL-20/DNDAP cocrystal and composite, and the interactions in the cocrystal are stronger than those in the composite. The maximum trigger bond length decreases in the order -CL-20 > CL-20/DNDAP composite > CL-20/DNDAP cocrystal. Moreover, the rigidity and stiffness of the cocrystal and composite decrease compared to that of CL-20, while the ductility and elasticity are better than that of the two pure components. These results demonstrate that CL-20/DNDAP cocrystal might be very promising in explosive applications. This work proves that cocrystallization is a more effective modification method than mixing and elucidated the underlying mechanism.