Desensitizing Effect of Graphene Oxide on Thermolysis Mechanisms of 4,4'-Azo-1,2,4-triazole Studied by Reactive Molecular Dynamics Simulations

Chongmin Zhang; Xiaolong Fu; Jizhen Li; Xuezhong Fan; Guofang Zhang

doi:10.1021/acs.jpca.8b10087

Desensitizing Effect of Graphene Oxide on Thermolysis Mechanisms of 4,4'-Azo-1,2,4-triazole Studied by Reactive Molecular Dynamics Simulations

J Phys Chem A. 2019 Feb 21;123(7):1285-1294. doi: 10.1021/acs.jpca.8b10087. Epub 2019 Feb 6.

Authors

Chongmin Zhang¹, Xiaolong Fu², Jizhen Li¹, Xuezhong Fan¹, Guofang Zhang²

Affiliations

¹ Xi'an Modern Chemistry Research Institute , Xi'an , 710065 , China.
² Key Laboratory of Applied Surface and Colloid Chemistry, MOE/School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710062 , China.

PMID: 30688461
DOI: 10.1021/acs.jpca.8b10087

Abstract

Graphene oxide (GO) has obvious desensitizing effect on the thermal decomposition of energetic materials such as HMX, CL-20, etc. 4,4'-Azo-1,2,4-triazole (ATRZ) is known as a new type of energetic material with high N content; the underlying thermal decomposition mechanism of graphene oxide-ATRZ (GO-ATRZ) complex with low sensitivity has not been studied. The present work studies the thermal decomposition mechanisms of GO, ATRZ,and the GO-ATRZ complex (the number of carboxyl groups on GO:ATRZ = 2:1) by the ReaxFF molecular reactive dynamic simulations and kinetics calculations. As a result, it has been found that the main decomposition pathway of GO is the exfoliation of hydroxyl and carboxyl groups on the graphene sheet, whereas ATRZ breaks its five-membered ring as the main decomposition path, and the ring further decomposes into small molecules, such as CHN, N₂, HN₂, H₂N₂, etc. The major effect of GO on ATRZ is probably derived from the stable graphene sheet, which has a space effect on ATRZ, and the strong oxidizing hydroxyl groups produced during GO decomposition, which results in the formation of CON and CHON. By calculating the activation energy of N₂ generation in the reactions, it can be concluded that the addition of GO can increase the decomposition activation energy of ATRZ (41.1 kJ·mol^-1) in comparison with that of its pure substance (25.0 kJ·mol^-1). Therefore, GO can be combined with ATRZ as a desensitizer where GO can improve the molecular stability of ATRZ.