Nikita V. Muravyev

Pyrazole‐Tetrazole Hybrid bearing the Trinitromethyl, Fluorodinitromethyl or (Difluoroamino)dinitromethyl Groups: High‐Performance Energetic Materials

High-nitrogen-content compounds have attracted great scientific interest and technological importance because of their unique energy content, and they find diverse applications in many fields of science and technology. Understanding of structure-property relationship trends and how to modify them is of paramount importance for their further improvement. Herein, the installation of oxygen-rich modules, C(NO2 )3 , C(NO2 )2 F, or C(NO2 )2 NF2 , into an endothermic framework, that is, the combination of a nitropyrazole unit and tetrazole ring, is used as a way to design novel energetic compounds. Density, oxygen balance, and enthalpy of formation are enhanced by the presence of these oxygen-containing units. The structures of all compounds were confirmed by XRD. For crystal packing analysis, it is proposed to use new criterion, ΔOED , that can serve as a measure of the tightness of molecular packing upon crystal formation. Overall, the materials show promising detonation and propulsion parameters.

Synergistic Effect of Ammonium Perchlorate on HMX: From Thermal Analysis to Combustion

The thermal decomposition and combustion of binary mixture of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and ammonium perchlorate (AP) are investigated at various concentrations. Thermal stability was investigated by thermal analysis techniques, i.e., DSC/TGA, combined with FTIR spectrometry, and accelerating rate calorimetry (ARC). Twofold HMX/AP interaction result is observed: ammonium perchlorate as synergistic additive effectively (in 60 °C) reduces the onset decomposition temperature of HMX, whereas gaseous products of the HMX thermolysis, in turn, catalyze the AP decomposition. Burning rate of mechanical mixtures exceeds the HMX level at 4 MPa, when HMX content lies in the range close to above synergistic effect at thermolysis, and AP particle size is fine (10 μm). Addition of large AP particles to HMX does not enhance the burning rate. Comparative analysis of the combustion parameters of the mechanical mixtures and large HMX crystals covered with AP layer revealed that the direct contact between components is not a necessary condition for the HMX/AP interaction for compositions without binder, proving the gas-phase character of this effect. However, for compositions with active binder, the direct contact between components is important. Finally, the synergistic effect changes the decomposition pathway for mixtures with HMX content above 40 % and below 90 % and noticeably increases the burning rate of HMX-based compositions with active binder. Formulations with active binder and coated HMX provide higher burning rate than those ones with mechanical mixtures of HMX with fine AP. It means the possibility to use the considerably less amount of ammonium perchlorate to achieve the same level of the burning rate.

Azasydnone – Novel 'green' building block for designing high energetic compounds

The discovery of novel explosophoric building blocks for the construction of energetic compounds is extremely rare. Here, based on the comparative experimental properties and computational analysis of compounds where nitroaryl backbones were bonded with various nitrogen/oxygen-rich groups, it is shown that compounds having the azasydnone group possess higher density, detonation performance and thermal stability than their corresponding nitro, azido and tetrazole-analogs. All of these properties, as well as the oxygen balanced content of the “green” nitrogen rich endothermic unit make them an attractive explosophoric building block in the field of energetic materials chemistry.