title: Theoretical insight into the binding energy and detonation performance of ε-, γ-, β-CL-20 cocrystals with β-HMX, FOX-7, and DMF in different molar ratios, as well as electrostatic potential.
abstract: Molecular dynamics method was employed to study the binding energies on the selected crystal planes of the ε-, γ-, β-conformation 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (ε-, γ-, β-CL-20) cocrystal explosives with 1,1-diamino-2,2-dinitroethylene (FOX-7), 1,3,5,7-tetranitro- 1,3,5,7-tetrazacyclooctane with β-conformation (β-HMX) and N,N-dimethylformamide (DMF) in different molar ratios. The oxygen balance, density, detonation velocity, detonation pressure, and surface electrostatic potential were analyzed. The results indicate that the binding energies E b (*) and stabilities are in the order of 1:1 > 2:1 > 3:1 > 5:1 > 8:1 (CL-20:FOX-7/β-HMX/DMF). The values of E b (*) and stabilities of the energetic-nonenergetic CL-20/DMF cocrystals are far larger than those of the energetic-energetic CL-20/FOX-7 and CL-20/β-HMX, and those of CL-20/β-HMX are the smallest. For CL-20/FOX-7 and CL-20/β-HMX, the largest E b (*) appears in the cocrystals with the 1:1, 1:2 or 1:3 molar ratio, and the stabilities of the cocrystals with the excess ratio of CL-20 are weaker than those in the cocrystals with the excess ratio of FOX-7 or β-HMX. In CL-20/FOX-7, CL-20 prefers adopting the γ-form, and ε-CL-20 is the preference in CL-20/β-HMX, and ε-CL-20 and β-CL-20 can be found in CL-20/DMF. The CL-20/FOX-7 and CL-20/β-HMX cocrystals with low molar ratios can meet the requirements of low sensitive high energetic materials. Surface electrostatic potential reveals the nature of the sensitivity change upon the cocrystal formation. Graphical Abstract MD method was employed to study the binding energies on the selected crystal planes in the ε-, γ-, β-CL-20 cocrystals with FOX-7, β-HMX and DMF in different molar ratios. Surface electrostatic potential reveals the nature of the sensitivity change in cocrystals.
authors.affiliation: School of Chemical and Environmental Engineering, North University of China, Taiyuan, 030051, China. fengruizhi1@hotmail.com.
authors.forename: Rui-Zhi
authors.initials: RZ
authors.lastname: Feng
authors.affiliation: School of Chemical and Environmental Engineering, North University of China, Taiyuan, 030051, China.
authors.forename: Shu-Hai
authors.initials: SH
authors.lastname: Zhang
authors.affiliation: School of Chemical and Environmental Engineering, North University of China, Taiyuan, 030051, China.
authors.forename: Fu-de
authors.initials: FD
authors.lastname: Ren
authors.affiliation: School of Chemical and Environmental Engineering, North University of China, Taiyuan, 030051, China.
authors.forename: Rui-Jun
authors.initials: RJ
authors.lastname: Gou
authors.affiliation: School of Chemical and Environmental Engineering, North University of China, Taiyuan, 030051, China.
authors.forename: Li
authors.initials: L
authors.lastname: Gao
keywords: Binding energy; Cocrystal; Detonation performance; Electrostatic potential; Molar ratio; Molecular dynamics