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Decomposition mechanism scenarios of CL-20 co-crystals revealed by ReaxFF molecular dynamics: similarities and differences

Abstract

Understanding on the similarities and differences of decomposition mechanisms of CL-20 and its cocrystals is of great interest for practical applications of CL-20 cocrystals. The responses of CL-20 cocrystals to thermal stimulus were investigated using ReaxFF molecular dynamics simulations of two representative cocrystals CL-20/HMX and CL-20/TNT at adiabatic conditions against the baseline system of pure CL-20. The comprehensive chemical details were revealed with aid of the unique code of VARxMD. The three CL-20-involved reactive systems all exhibit distinct three-stage character during adiabatic decomposition when using the double peaks of major intermediate NO2 amount as boundary. By taking advantage of the three-stage classification, a clear scenario for the similar stimulus-response of the CL-20 cocrystals can be elucidated for the dominant primary decomposition of CL-20 in stage I and the transition of favored chemical mechanisms from generation of intermediates/radicals in stage II into their consumption to form stable products in stage III. The similar chemical behaviors are rooted in the dominance of CL-20 chemistry in initial response of its cocrystals to thermal stimulus. The prolonged reaction zone uncovers the slowed decomposition kinetics of CL-20/HMX and CL-20/TNT, which is associated with the altered kinetics of CL-20 decomposition specifically by N-NO2 bond scission and CL-20 skeleton decay. The retarded CL-20 decomposition in its cocrystals consequently results in more moderate self-heating and less violent exothermic reactions that agrees with the experimental observations of improved stability and damaged detonation performance of CL-20 cocrystals particularly for CL-20/TNT. What obtained in this work suggests that ReaxFF MD simulations can provide useful insight for the modulated chemical properties of varied CL-20 cocrystals.

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Supplementary files

Article information


Submitted
10 Nov 2019
Accepted
24 Dec 2019
First published
07 Jan 2020

Phys. Chem. Chem. Phys., 2020, Accepted Manuscript
Article type
Paper

Decomposition mechanism scenarios of CL-20 co-crystals revealed by ReaxFF molecular dynamics: similarities and differences

C. Ren, H. Liu, X. Li and L. Guo, Phys. Chem. Chem. Phys., 2020, Accepted Manuscript , DOI: 10.1039/C9CP06102A

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