2 research outputs found
Combination Multinitrogen with Good Oxygen Balance: Molecule and Synthesis Design of Polynitro-Substituted Tetrazolotriazine-Based Energetic Compounds
We investigated 5,8-dinitro-5,6,7,8-tetrahydrotetrazolo[1,5-<i>b</i>][1,2,4]triazine (short for DNTzTr (<b>1</b>)) using
various ab initio quantum chemistry methods. We proposed an additional
three novel polynitro-substituted tetrazolotriazine-based compounds
with exceptional performance, including 5,8-dinitro-5,6-dioxotetrazolo[1,5-<i>b</i>][1,2,4]triazine, DNOTzTr (<b>2</b>), 4,5,9,10-tetranitro[1,2,4,5]tetrazolo[3,4-<i>b</i>][1,2,4,5]tetrazolo[3′,4′:5,6]triazino[2,3-<i>e</i>]triazine, TNTzTr (<b>3</b>), and 4,5,6,10,11,12-hexanitro-bis[1,2,4,5]tetrazolo[3′,4′:5,6]triazino[2,3-<i>b</i>:2′,3′-<i>e</i>]triazine, HNBTzTr
(<b>4</b>). The optimized structure, electronic density, natural
bond orbital (NBO) charges and HOMO–LUMO orbitals, electrostatic
potential on surface of molecule, IR- and NMR-predicted spectra, as
well as thermochemical parameters were calculated with the B3LYP/6-311+G(2d)
level of theory. Critical parameters such as density, enthalpy of
formation (EOF), and detonation performance have also been predicted.
Characters with positive EOF (1386.00 and 1625.31 kJ/mol), high density
(over 2.00 g/cm<sup>3</sup>), outstanding detonation properties (<i>D</i> = 9.82 km/s, <i>P</i> = 45.45 GPa; <i>D</i> = 9.94 km/s, <i>P</i> = 47.30 GPa), the perfect oxygen
balance set to zero, and acceptable impact sensitivity led novel compounds <b>3</b> and <b>4</b> to be very promising energetic materials.
This work provides the theoretical molecule design and a reasonable
synthesis path for further experimental synthesis and testing
The Mitigation Effect of Synthetic Polymers on Initiation Reactivity of CL-20: Physical Models and Chemical Pathways of Thermolysis
In this paper, the thermal decomposition
physical models of different CL-20 polymorph crystals and their polymer
bonded explosives (PBXs) bonded by polymeric matrices using polyisobutylene
(PIB), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber
(SBR), Viton A, and Fluorel binders are obtained and used to predict
the temperature profiles of constant rate decomposition. The physical
models are further supported by the detailed decomposition pathways
simulated by a reactive molecular dynamics (ReaxFF-lg) code. It has
been shown that both ε-CL-20 and α-CL-20 decompose in
the form of γ-CL-20, resulting in close activation energy (169
kJ mol<sup>–1</sup>) and physical model (first-order autoaccelerated
model, AC1). Fluoropolymers could change the decomposition mechanism
of ε-CL-20 from the “first-order autocatalytic”
model to a “three-dimensional nucleation and growth”
model (A3), while the polymer matrices of Formex P1, Semtex, and C4
could change ε-CL-20 decomposition from a single-step process
to a multistep one with different activation energies and physical
models. Compared to fluoropolymers, PIB, SBR and NBR may make ε-CL-20
undergo more complete N–NO<sub>2</sub> scission before collapse
of the cage structure. This is likely the main reason why those polymer
bases could greatly mitigate the decomposition process of ε-CL-20
from a single step to a multistep, resulting in lower impact sensitivity,
whereas fluoropolymers have only a little effect on that. For ε-CL-20
and its PBXs, the impact sensitivity depends not only on the heat
built-up period of their decomposition, but also on the probability
of hotspot generation (defects in solid crystals and interfaces) especially
when it decomposes in a solid state