Zhang Chongmin, Fu Xiaolong, Li Jizhen, Fan Xuezhong, Zhang Guofang
Xi'an Modern Chemistry Research Institute , Xi'an , 710065 , China.
Key Laboratory of Applied Surface and Colloid Chemistry, MOE/School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710062 , China.
J Phys Chem A. 2019 Feb 21;123(7):1285-1294. doi: 10.1021/acs.jpca.8b10087. Epub 2019 Feb 6.
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, N, HN, HN, 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 N 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) in comparison with that of its pure substance (25.0 kJ·mol). Therefore, GO can be combined with ATRZ as a desensitizer where GO can improve the molecular stability of ATRZ.
氧化石墨烯（GO）对奥克托今（HMX）、六硝基六氮杂异伍兹烷（CL - 20）等含能材料的热分解具有明显的钝化作用。4,4'-偶氮-1,2,4-三唑（ATRZ）是一种新型的高氮含量含能材料；低敏感度的氧化石墨烯-ATRZ（GO-ATRZ）复合物潜在的热分解机理尚未得到研究。本工作通过ReaxFF分子反应动力学模拟和动力学计算研究了GO、ATRZ以及GO-ATRZ复合物（GO上羧基与ATRZ的比例为2:1）的热分解机理。结果发现，GO的主要分解途径是石墨烯片层上羟基和羧基的剥离，而ATRZ以其五元环断裂作为主要分解路径，该环进一步分解为小分子，如CHN、N、HN、HN等。GO对ATRZ的主要影响可能源于稳定的石墨烯片层对ATRZ的空间效应，以及GO分解过程中产生的强氧化性羟基，这导致了CON和CHON的形成。通过计算反应中生成N的活化能，可以得出，与ATRZ纯物质（25.0 kJ·mol）相比，添加GO可提高ATRZ的分解活化能（41.1 kJ·mol）。因此，GO可与ATRZ复合作为钝化剂，其中GO可提高ATRZ的分子稳定性。
