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Reaction mechanism from quantum molecular dynamics for the initial thermal decomposition of 2,4,6-triamino-1,3,5-triazine-1,3,5-trioxide (MTO) and 2,4,6-trinitro-1,3,5-triazine-1,3,5-trioxide (MTO3N), promising green energetic materials

Ye, Cai-Chao and An, Qi and Cheng, Tao and Zybin, Sergey and Naserifar, Saber and Ju, Xue-Hai and Goddard, William A., III (2015) Reaction mechanism from quantum molecular dynamics for the initial thermal decomposition of 2,4,6-triamino-1,3,5-triazine-1,3,5-trioxide (MTO) and 2,4,6-trinitro-1,3,5-triazine-1,3,5-trioxide (MTO3N), promising green energetic materials. Journal of Materials Chemistry A, 3 (22). pp. 12044-12050. ISSN 2050-7488. https://resolver.caltech.edu/CaltechAUTHORS:20150518-144926208

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Abstract

Klapötke and co-workers recently designed two new materials, 2,4,6-triamino-1,3,5-triazine-1,3,5-trioxide (MTO) and 2,4,6-trinitro-1,3,5-triazine-1,3,5-trioxide (MTO3N), envisioned as candidates for green high-energy materials. However, all attempts at synthesis have failed. In order to validate the expected properties for these systems and to determine why these materials are too unstable to synthesize, we used the PBE flavor of Density Functional Theory (DFT) to predict the crystal structures for MTO and MTO3N and then we carried out DFT molecular dynamics simulations (DFT-MD) to determine the initial reaction mechanisms for decomposition. Klapötke estimated that MTO would have a density of ρ = 1.859 g cm^(−3) with an estimated detonation velocity (D_v) of 8.979 km s^(−1), making it comparable to RDX (ρ = 1.82 g cm^(−3), D_v = 8.75 km s^(−1)) and β-HMX (ρ = 1.91 g cm^(−3), D_v = 9.10 km s^(−1)). His estimated impact sensitivity >30 J, make it much better than HMX (7 J) and RDX (7.5 J). Our predicted crystal structure for MTO (P2_(1) space group) leads to ρ = 1.859 g cm^(−3), in good agreement with expectations. Our DFT-MD studies find that the first step in the decomposition of MTO is intermolecular hydrogen-transfer reaction (barrier 3.0 kcal mol^(−1)) which is followed quickly by H_2O and NO release with reaction barriers of 46.5 and 35.5 kcal mol^(−1). In contrast for MTO3N (P2_(1)/c predicted space group), we find that the first steps are a bimolecular decomposition to release NO_2 (ΔH = 44.1 kcal mol^(−1), ΔG = 54.7 kcal mol^(−1)) simultaneous with unimolecular NO_2 cleavage (ΔH = 59.9 and ΔG = 58.2 kcal mol^(−1)) a unique initial reaction among EMs. These results suggest that MTO3N would be significantly more thermally stabile (barrier > 6.0 kcal mol^(−1) higher) than RDX and HMX, making it an excellent candidate to be insensitive new green energetic materials. However we find that MTO leads to very favorable hydrogen transfer reactions that may complicate synthesis and crystallization, making MTO3N the more promising system.


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Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1039/C5TA02486BDOIArticle
http://pubs.rsc.org/en/content/articlelanding/2015/ta/c5ta02486bPublisherArticle
http://www.rsc.org/suppdata/c5/ta/c5ta02486b/c5ta02486b1.pdfRelated ItemSupporting Information
ORCID:
AuthorORCID
Ye, Cai-Chao0000-0002-9197-8922
An, Qi0000-0003-4838-6232
Cheng, Tao0000-0003-4830-177X
Naserifar, Saber0000-0002-1069-9789
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2015 The Royal Society of Chemistry. Received 6th April 2015. Accepted 24th April 2015. This research was funded by ONR (N00014-09-1-0634, Cliff Bedford). C.-C. Ye was sponsored by the China Scholarship Council, and thanks the Innovation Project for Postgraduates in Universities of Jiangsu Province (Grant no. CXZZ13_0213).
Funders:
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-09-1-0634
China Scholarship CouncilUNSPECIFIED
Innovation Project for Postgraduates in Universities of Jiangsu ProvinceCXZZ13_0213
Issue or Number:22
Record Number:CaltechAUTHORS:20150518-144926208
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150518-144926208
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:57617
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:18 May 2015 22:16
Last Modified:03 Oct 2019 08:26

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