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A series of isomers of tetranitro-bis-1,2,4-triazoles were designed, and their electronic structures, heats of formation, densities, detonation performances, thermal stabilities, and impact sensitivities were investigated by density functional theory (DFT). The structure and energetic properties of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) were also calculated at the same level. On comparing with the detonation velocity and pressure and bond dissociation energy (BDE) of HMX, it was found that four isomers (BT2, BT5, BT6, BT7) have higher detonation performances than HMX and three isomers (BT5, BT6, BT7) have better thermal stabilities than HMX. The calculated results of impact sensitivities indicated that all of the designed isomers have more sensitivity than HMX. The calculated results of energy gaps between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) indicated that all of the designed isomers were more easily excited than HMX in the chemical reaction process. In particular, 3,3′,5,5′-tetranitro-1,1′-bis-1,2,4-triazoles (BT5) exhibited excellent detonation performances (9464 m s–1, 39.44 GPa) and good thermal stability (BDE 256.81 kJ mol–1). The results indicated that the isomerization of tetranitro-bis-1,2,4-triazoles could improve their detonation performance or thermal stability and might lead to a promising isomer possessing both good performance and high thermal stability.

1,1-Diamino-2,2-dinitroethylene (FOX-7) is well-known as one high-energy insensitive material. The size effect of the nano-crystal on the pyrolysis are extremely important for ignition and reaction pathways under extreme conditions. The thermal decomposition of nano-FOX-7 was investigated utilizing molecular dynamics method with reactive force field. The pyrolysis simulation showed that the potential barrier of nano-FOX-7 at 3000 K are higher than that at 2000 K. The temperature distribution of nano-FOX-7 in the temperature-rise periods shows that the decomposition occurs first at the central part of the crystal. Based on the analysis of chemical species, three types of initial reaction pathways were identified, among which the fission of the C–NH2 bond may be a new reaction pathway. A decomposition network from initial reactant to the main products was proposed to provide insights into the decomposition mechanism on atomic level. The mass distribution of products showed that the clusters among the decomposition products can inhibit the violent reaction to a certain extent. In addition, the analysis of the nano-crystal effect on the FOX-7 decay shows that the numbers of N2 and CO2 are related to the nanoparticle size.

We report a reactive molecular dynamic (ReaxFF-MD) study using the newly parameterized ReaxFF-lg reactive force field to explore the initial decomposition mechanism of 3-Nitro-1,2,4-triazol-5-one (NTO) under shock loading (shock velocity &gt, 6 km/s). The new ReaxFF-lg parameters were trained from massive quantum mechanics data and experimental values, especially including the bond dissociation curves, valence angle bending curves, dihedral angle torsion curves, and unimolecular decomposition paths of 3-Nitro-1,2,4-triazol-5-one (NTO), 1,3,5-Trinitro-1,3,5-triazine (RDX), and 1,1-Diamino-2,2-dinitroethylene (FOX-7). The simulation results were obtained by analyzing the ReaxFF dynamic trajectories, which predicted the most frequent chain reactions that occurred before NTO decomposition was the unimolecular NTO merged into clusters ((C2H2O3N4)n). Then, the NTO dissociated from (C2H2O3N4)n and started to decompose. In addition, the paths of NO2 elimination and skeleton heterocycle cleavage were considered as the dominant initial decomposition mechanisms of NTO. A small amount of NTO dissociation was triggered by the intermolecular hydrogen transfer, instead of the intramolecular one. For α-NTO, the calculated equation of state was in excellent agreement with the experimental data. Moreover, the discontinuity slope of the shock-particle velocity equation was presented at a shock velocity of 4 km/s. However, the slope of the shock-particle velocity equation for β-NTO showed no discontinuity in the shock wave velocity range of 3–11 km/s. These studies showed that MD by using a suitable ReaxFF-lg parameter set, could provided detailed atomistic information to explain the shock-induced complex reaction mechanisms of energetic materials. With the ReaxFF-MD coupling MSST method and a cheap computational cost, one could also obtain the deformation behaviors and equation of states for energetic materials under conditions of extreme pressure.

The solidification point is a key quality parameter for 2,4,6-trinitrotoluene (TNT). The traditional solidification point measurement method of TNT is complicated, dangerous, not environmentally friendly and time-consuming. Near infrared spectroscopy (NIR) analysis technology has been applied successfully in the chemical, petroleum, food, and agriculture sectors owing to its characteristics of fast analysis, no damage to the sample and online application. The purpose of this study was to study near infrared spectroscopy combined with chemometric methods to develop a fast and accurate quantitative analysis method for the solidification point of TNT. The model constructed using PLS regression was successful in predicting the solidification point of TNT ([Formula: see text] = 0.999, RMSECV = 0.19, RPDCa = 33.5, [Formula: see text] = 0.19, [Formula: see text] = 0.999). Principal component analysis shows that the model could identify samples from different reactors. The results clearly demonstrate that the solidification point can be measured in a short time by NIR spectroscopy without any pretreatment for the sample and skilled laboratory personnel.

3,4,5-Trinitro-1H-pyrazole (TNP) is a novel all-carbon nitrated azole energetic compound with excellent potential, whose explosion and safety performance is affected by its crystal morphology. In this study, an attachment energy (AE) model was employed to study the growth habit of TNP in vacuum and predict the results of the growth habit of the TNP crystals grown from benzene, toluene, dichloromethane and water by the molecular dynamics simulation. The interactions between the solvent molecules and crystal faces were analyzed. The period bond chains (PBCs) of the crystal faces were calculated. The TNP crystals were obtained by the natural cooling experiments in benzene, toluene, dichloromethane and water, respectively. The {1 0 0} crystal form had the largest morphological importance for the TNP crystal habit in vacuum, followed by the {0 1 1} and {0 0 1} forms in turn. The crystal morphology was significantly influenced by the he interactions between the solvent molecules and crystal face. There were three different crystal shapes that are flaky, columnar, and blocky. The aspect ratios of the habit in benzene, toluene, dichloromethane and water were 19.42, 5.65, 5.31 and 3.55, respectively. The predicted TNP morphologies qualitatively agreed with those from the experiment.

The low stability and poisoning of the palladium-based catalysts in the debenzylation of HBIW elevated the cost of the hydrogenolysis, and thus restricted the application of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (HNIW). To address this problem, Pd/mpg-C3N4 was prepared by depositing palladium nanoparticles on mesoporous graphite carbon nitride (mpg-C3N4), and used for the catalytic hydrogenolysis in the conversion of HBIW to TADBIW under the atmospheric pressure. After optimizing the reaction condition and the usage amount, the highest yield of 81.7 % was obtained at 45℃ after reaction for 8 h when the ratio of palladium to HBIW was 1%. A yield of 74 % was obtained when the ratio of palladium to HBIW was 0.4 %. More importantly, Pd/mpg-C3N4 can be recycled unprecedently for three times in the conversion of HBIW to TADBIW while preserving the reasonable activity. Such results should benefit for promoting the application of HNIW and also the design of the heterogeneous catalysts for hydrodebenzylation.

A computational strategy in consideration of the crystal surface structures was proposed based on the attachment energy model to unravel of the effect of solvent on the crystal morphology. The proposed strategy is confirmed by its successful applications to predict the crystal morphology of FOX-7 growth in DMSO. The analysis results of the binding energy composition between the solvent and the crystal show that the adsorption of DMSO molecules on the surface with nitro groups is mainly through forming hydrogen bonds, whereas the adsorption on the surface with amino groups is mainly due to the van der Waals interaction.