Abstract:Starting from 3,5-dichloroanisole, 2,4,6-trinitro-3,5-dichloroanisole was obtained via nitration with mixed acid, which was then reacted with 4-aminopyrazole to afford 3-chloro-5-methoxy-2,4,6-trinitro-N-(1H-pyrazol-4-yl)aniline (1). Subsequent nitration of compound 1 with fuming nitric acid followed by amination with aqueous ammonia successfully yielded N-(3,5-diamino-2,4,6-trinitrophenyl)-3,5-dinitro-1H-pyrazol-4-amine (4). The structures of the target compounds were characterized by fourier transform infrared spectroscopy, nuclear magnetic resonance, elemental analysis and single-crystal X-ray diffraction. The detonation properties were calculated using the EXPLO5 software. A simultaneous thermogravimetry-differential scanning calorimetry analyzer and impact/friction sensitivity testers were employed to determine the thermal decomposition temperature and mechanical sensitivities, respectively. The results show that compound 4 crystallizes in the monoclinic crystal system with the P21 space group. Its unit cell parameters are a=6.2175(2) Å, b=9.2348(4) Å, c=12.5837(5) Å, giving a density of 1.91 g?cm-3 (170 K). The theoretical detonation velocity and detonation pressure are 8576 m?s-1 and 32.1 GPa, respectively. Its thermal decomposition temperature is 217 ℃; the impact sensitivity is 15 J and the friction sensitivity is 160 N. Compound 4 exhibits favorable detonation performance and thermal stability.

Abstract:To reveal the mechanism by which oriented alignment of thermally conductive fillers enhances the thermal conductivity of polymer matrix composites， a two-dimensional steady-state heat conduction numerical model was established for graphene/fluoropolymer composites. The effects of filler volume fraction， aspect ratio， and orientation angle on the effective thermal conductivity of the composites were systematically investigated. The results show that the effective thermal conductivity of the composite increases with the rise of graphene volume fraction and aspect ratio， but decreases with the increase of orientation angle. Graphene orientation exhibits a significant regulatory effect on directional thermal conductivity， and there is a cosine relationship between orientation angle and effective thermal conductivity， with the average coefficient of determination R² of the fitting equation exceeding 0.99. At a volume fraction of 30% and an aspect ratio of 20∶1， as the orientation angle decreases from 90° to 10°， the effective thermal conductivity of the composite increases from 0.233 W·m^-1·K^-1 to 1.285 W·m^-1·K^-1， representing an increase of approximately 450%. This study demonstrates that oriented alignment of thermally conductive fillers can optimize the geometric matching between fillers and heat flow direction， improving the continuity and directionality of internal heat conduction pathways in composites， thereby significantly enhancing thermal transport capability along the target direction. The results can provide a theoretical basis for the structural design and performance regulation of thermally anisotropic high-thermal-conductivity composites.

Abstract:A novel dinitramine compound, N,N’-[5,5’-bis(trinitromethyl)-3,3’-bi-1,2,4-triazol]dinitramide (3), was synthesized via N-amination and subsequent nitration of the starting material 3,3’-bi(1H,1’H-1,2,4-triazole)-5,5’-bis(trinitromethyl) (1). The structure of compound 3 was confirmed by X-ray single-crystal diffraction (XRD) and further characterized by infrared spectroscopy (IR), elemental analysis (EA), and nuclear magnetic resonance (NMR) spectroscopy. The enthalpy of formation for compound 3 was calculated using the isodesmic reaction method, while its detonation performance was predicted using the EXPLO5 code. Results indicate that compound 3 crystallizes in the monoclinic space group P21/n. The crystal density of the dihydrate (3•2H2O) is 1.937 g•cm-3 at 100 K. It exhibits an initial decomposition temperature of 92.6 ℃ and a calculated enthalpy of formation of 680.5 kJ•mol-1. Furthermore, its predicted detonation velocity and pressure are 8926 m•s-1 and 34.1 GPa, respectively, with a specific impulse of 257.7 s. Its integrated performance suggests its potential for use as an energetic oxidizer.

Abstract:To investigate the regulatory mechanism of amino and nitro substituents on the thermal stability of TYX series heat-resistant explosives， two novel heat-resistant explosives based on the bis（triazolo）tetrazine backbone-fully amino-substituted 2，7-diaminobis（［1，2，4］triazolo）［1，5-b：1'，5'-e］［1，2，4，5］tetrazine-5，10-diium-3，8-diide （TYX-1） and mono-nitro mono-amino substituted 2-amino-7-nitrobis（［1，2，4］triazolo）［1，5-b：1'，5'-e］［1，2，4，5］tetrazine-5，10-diium-3，8-diide （TYX-3）-were selected in this study. Their thermal decomposition behaviors were systematically compared using differential scanning calorimetry （DSC） and thermal decomposition kinetic methods， while the decomposition processes were comprehensively analyzed by thermogravimetry-infrared-mass spectrometry （TG-FTIR-MS）. The results show that the difference in substituents exerts a decisive influence on their thermal stability and decomposition pathways. TYX-1 exhibits a single high-temperature decomposition process with a peak temperature of 477.56 ℃ （at a heating rate of 20 ℃·min^-1）， and its decomposition mechanism conforms to the random two-dimensional nucleation growth model （A2）， consistent with the layered stacking structure promoted by amino groups and the resulting controlled two-dimensional energy release pathway. In contrast， TYX-3 shows a significantly lower decomposition temperature and multi-step decomposition characteristics： the initial stage follows a two-dimensional diffusion model （D2）， followed by a multi-reaction competitive stage， and finally transitions to a skeletal fracture process dominated by the one-dimensional chemical reaction model （F1）. Gas product analysis shows that the main decomposition products of TYX-1 are N₂， CO₂， N₂O， and HCN， while additional products including NO， HCNO， NH₂， and H₂O are detected for TYX-3， confirming that the nitro group， as a strong oxidizing moiety， induces an unconventional decomposition pathway and promotes the oxidative cleavage of the parent ring skeleton.

Abstract:To investigate the evolution of the mechanical sensitivity of the energetic oxidizer ammonium dinitramide （ADN） under varying moisture and temperature conditions， standard tests specified by the Federal Institute for Materials Research and Testing （BAM） were carried out in combination with the Langlie–D optimization method. The impact and friction sensitivities of ADN samples with moisture contents of 0， 5%， 10%， and 15% were quantitatively evaluated at 25， 50， and 75 ℃. The results show that both impact and friction sensitivities decrease significantly with increasing moisture content， although the variation is not simply linear and instead exhibits a distinct stagewise pattern. At 25 ℃， the limiting impact energy increased from 4 J for anhydrous ADN to 30 J at 5% moisture content and exceeded 50 J when the moisture content reached 10% or higher. Meanwhile， the minimum friction load increased progressively from 56 N and surpassed the upper measurement limit of the apparatus at 15% moisture content. Further analysis indicates that increasing temperature gradually weakens the desensitizing effect of moisture. At a given moisture content， both the limiting impact energy and the minimum friction load at 50 and 75 ℃ are generally lower than those at 25 ℃， while the corresponding impact and friction ignition-probability curves shift continuously toward lower stimulus levels. Among them， friction sensitivity shows a stronger dependence on temperature. These results suggest that the coupled effects of moisture content and temperature are reflected not only in single threshold values， but also in systematic shifts of the entire ignition-probability curve and the corresponding low-probability risk boundary.

Abstract:To clarify the evolution mechanism of the gas curtain flow field during underwater launch and optimize the in-tube drainage efficiency， this study investigates the effects of different injection pressure conditions on the evolution characteristics of the gas curtain inside a spiral-grooved underwater gun tube. A transient three-dimensional two-phase flow model was established for the drainage process during underwater gas-curtain launch. Based on a 40 mm supercavitating projectile and a spiral-grooved gas-curtain launch tube， numerical simulations of gas curtain evolution were performed under four different injection pressure conditions， and the effect of the pressurization rate on key evolution characteristics was analyzed. The results show that a higher pressurization rate results in better overall drainage performance， but it also induces higher pressure ahead of the projectile. Specifically， as the pressurization rate increases from 1 MPa·ms^-1 to 4 MPa·ms^-1， the drainage completion time （i.e.， the time required for the gas curtain front to reach the muzzle） decreases from 14.4 ms to 11.8 ms， achieving an 18.1% improvement in time efficiency and a 25.7% increase in drainage capacity. However， upon completion of drainage， the pressure on the projectile surface increases from 3.7 MPa to 4.96 MPa， and the average pressure inside the tube rises from 4.14 MPa to 5.47 MPa. In conclusion， although a high pressurization rate can significantly accelerate drainage， it substantially increases the subsequent in-tube motion resistance of the projectile. Therefore， in the practical matching design of propellant charge and projectile， it is necessary to comprehensively balance drainage efficiency and initial motion resistance， and reasonably control the injection pressure gradient.

Abstract:The inherent conflict between high energy density and low mechanical sensitivity represents a central challenge in the field of energetic materials. Although traditional nitramine compounds such as RDX， HMX， and CL-20 have significantly enhanced energy levels， they remain constrained by this trade-off. To explore new pathways for overcoming conventional performance limitations， researchers have proposed a strategy centered on rigid， planar fused-ring frameworks， leading to the development of nitrogen-rich fused-ring compounds. This review systematically outlines the evolution of this field， from the design of monocyclic systems （e.g.， azoles， azines， and 1，2，5-oxadiazoles） to the integrated design of binary fused-ring systems. It highlights the conceptual design of representative molecules， key advances in synthetic methodologies—ranging from oxidative nitration to controlled rearrangement reactions—and the regulatory mechanisms of intermolecular interactions such as hydrogen-bonding networks and π-π stacking on material performance. This progression illustrates a paradigm shift from empirical trial-and-error to rational design and function-oriented customization. Finally， addressing the synthetic bottlenecks that constrain practical application， this review proposes that future breakthroughs require synergistic efforts across three dimensions： design， preparation， and application. This includes developing design methods that balance performance with synthetic feasibility， promoting synthetic technologies with improved safety profiles， and expanding the application scope of fused-ring energetic materials， thereby facilitating the transition from molecular design to practical implementation and providing a foundation for next-generation high-performance energetic materials.

Abstract:Stereoisomerism plays a unique role in tuning the structures and performances of energetic molecules. Photochemical reactions feature mild conditions and precise configurational regulation thus bear important theoretical and practical significance for realizing stereoisomeric transformation of energetic molecules. (E)-Potassium 5,5'-azotetrazolate (E-PZT) was employed as the substrate in this work. Systematic condition screening was conducted to determine the optimal parameters for the photochemical synthesis of (Z)-potassium 5,5'-azotetrazolate (Z-PZT). The molecular structure of Z-PZT was fully characterized. The half-life of Z-PZT is measured to be 49 min at room-temperature. Theoretical calculations highly consistent with the experimental phenomena and results of the photoinduced isomerization reaction. The predicted excitation wavelengths and corresponding spectra obtained from theoretical calculations are highly consistent with the experimental phenomena and results of the photoinduced isomerization reaction. The successful preparation of the target product Z-PZT is further verified by these theoretical results. The isomerization energy barrier was calculated, and a rational photochemical reaction mechanism was accordingly proposed to elucidate the metastable characteristic of Z-PZT and the intrinsic origin of its relatively short half-life. Reliable experimental and theoretical support is provided by this work for the investigation of photoinduced isomerization regulation in energetic molecules.

Abstract:In order to meet the multiple requirements of high safety， low cost， high temperature resistance， and high pressure resistance on the seismic source for deep oil exploration， a kind of high-voltage switch consisting of two gas discharge tubes （GDTs） was used to control the discharge of thin film capacitor， and S-type bridge foil was exploded into high-temperature and high-pressure gas/plasma to ignite the boron potassium nitrate （BPN） pellet and generate underwater shock waves. Then， the ignition threshold of the seismic source was determined by the up-down method， and the acoustic characteristics were also studied using pressure probe. The results show that the firing unit composed of a thin film capacitor （2 μF） and the high-voltage switch based on GDTs can reliably achieve pulse discharge， and work at the extreme underground environments such as high temperature and high pressure， and the cost is less than ¥10. Using the firing unit to stimulate the S-type Cu bridge foil， a firing voltage threshold of 1100 V and a critical peak current of 1847 A were determined. The measurements of underwater shock waves and acoustic source level （ASL） analysis show that the ASL excited by the seismic source is higher than 150 dB in the 50-800 Hz frequency band， meeting the requirements of underground seismic sources.

Abstract:In order to explore the effect of aromatic compounds on the combustion performance of CMDB propellant， 2，2"-（propane-1，1-diyl）bis（4-（tert-butyl）phenol） （PDBP） was used to prepare HMX-CMDB propellant， and the combustion performance of HMX-CMDB propellants with different PDBP contents was studied using the target line method. The results showed that with the increase of PDBP content， the burning rate and pressure index of HMX-CMDB propellant significantly decreased. For HMX-CMDB propellant containing 7% PDBP， the burning rate at 16 MPa decreased to 8.55 mm·s^-1， and the pressure index decreased to 0.217. Compared with the sucrose octaacetate （SOA）， HMX-CMDB propellant containing the same mass of PDBP exhibited almost unchanged burning rate in the low-pressure region （8-10 MPa）， a further reduced burning rate in the high-pressure region （12-16 MPa）， resulting in a lower pressure index. In addition， after replacing SOA with 1% PDBP， the detonation heat of HMX-CMDB propellant was reduced by only 20 kJ/kg. Based on chemical structure analysis， the mechanism of PDBP"s burning rate inhibition effect is as follows： the aromatic molecule decompose to form protons and structurally stable radical molecules with conjugated π bonds， and the active protons can react with the active radicals released from the decomposition of energetic molecules in the HMX-CMDB propellant， forming stable structures that mitigate the autocatalytic effect of free radicals， thereby reducing the burning rate.