Abstract:In order to investigate the effect of aggregation structure on the properties of hexanitrohexaazaisowurtzitane/octogen （CL?20/HMX） co?crystal， the droplet confined crystallization was used to prepare spherical CL?20/HMX co?crystal. The morphology and structure of the samples were characterized by field emission scanning electron microscopy （FE?SEM）， X?ray powder diffraction （XRD） and fourier transform infrared spectroscopy （FT?IR）. The properties of the samples were analyzed by thermal analysis， sensitivity and combustion tests. The results show that the spherical CL?20/HMX co?crystal was successfully prepared by this method. The diameter of the spherical CL?20/HMX co?crystal is 1.3-1.85 mm， the hollow ratio is about 40%， and the specific surface area is 6.890 m2·g-1. The exothermic peak temperature of spherical CL?20/HMX co?crystal is located at 245.8 ℃ ， the thermal decomposition activation energy （463.02 kJ?mol-1） and the critical temperature of thermal explosion （241.28 ℃） are higher than those of flake CL?20/HMX co?crystal， exhibiting the excellent thermal stability of spherical CL?20/HMX. The impact sensitivity is better than that of raw material and flake CL?20/HMX co?crystal， and the friction sensitivity falls between raw CL?20 and HMX， but lower than that of flake CL?20/HMX co?crystal. The ignition delay time is less than 8 ms and the combustion is efficient and stable， while the flake CL?20/HMX co?crystal， raw materials and their physical mixture exhibit flameless combustion.The construction of millimeter?sized hollow spheres for CL?20/HMX co?crystal has significantly improved the thermal stability，sensibility and combustion performances.

Abstract:In order to understand the flow state of supercritical carbon dioxide （SC-CO₂）-assisted double-base propellant within the metering section during extrusion， and to analyze the distribution and variations of parameters such as pressure， fluid velocity， shear rate， and shear viscosity in the flow field， the CFD simulation software Polyflow was employed for simulating the flow state of the material in the metering section during SC-CO₂-assisted double-base propellant extrusion. The results show that both fluid pressure and shear viscosity decrease with increasing process temperature， gas injection rate， and solvent ratio. An increase in screw speed leads to a decrease in shear viscosity but a sharp increase in fluid pressure. The pressure on the outer wall of the fluid gradually increases in steps， with pressure at the cross-section exhibiting an approximately annular distribution， decreasing gradually from the inner wall of the barrel towards the screw surface. The shear viscosity at the cross-section forms a ring-shaped high-viscosity zone on the center of the screw. The closer the zone is to the inner wall of the barrel and the screw surface， the smaller the shear viscosity. Furthermore， changes in process parameters do not affect the distribution pattern of shear viscosity. The shear rate on the outer wall of the fluid increases with higher screw speed and concentrates at the thread. The maximum fluid velocity at the cross-section occurs near the thread， while the fluid velocity close to the inner wall of the barrel is minimal. As one moves away from the inner wall of the barrel and the screw surface， fluid velocity rapidly increases， with a greater gradient observed in zones closer to the screw surface and the inner wall of the barrel.

Abstract:In order to explore novel nitrogen-rich heterocyclic energetic compounds， an amide bridged energetic compound 1-hydroxy-N-（1H-1，2，4-triazol-3-yl）-1H-tetrazole-5-carboxamide was synthesized from 5-cyano-1-（1H-1，2，4-triazol-5-yl）-1H-tetrazole through several steps involving amidoximation， diazotization， substitution and electrophilic addition. Its structure was fully characterized by nuclear magnetic resonance （NMR）， Fourier transform infrared spectroscopy （FT-IR） and elemental analysis （EA）. X-ray diffraction analysis （SC-XRD） was adopted to further confirm its structure； its thermal decomposition process was studied by differential scanning calorimetry （DSC） and thermogravimetry （TG）. The compound has a high onset decomposition temperature of 265 ℃ and shows good properties with detonation velocity of 8017 m·s^-1， and detonation pressure of 23.1 GPa， impact sensitivity of 20 J， and friction sensitivity of 288 N.

Abstract:Solubility is an important parameter for the crystallization of molecular perovskite energetic materials （H₆N₂H₁₄）［NH₄（ClO₄）₃］（DAP-4）. In this work， the dissolution behaviors of DAP-4 at different temperatures （288-323 K） and in different solvents （ethanol， ethyl acetate， formic acid， deionized water， acetone， cyclohexane， methanol， acetonitrile， n-propanol） were studied by the gravimetric method. The dissolution models were established by the Apelblat equation and the λh equation， respectively. Meanwhile， the dissolution thermodynamic parameters （ΔH_d， ΔS_d， ΔG_d） were obtained by Van’t Hoff equation based on the thermodynamic principle of solid-liquid equilibrium. Results show that the solubility of DAP-4 is the largest in water and the smallest in ethyl acetate， which are increased with the increasing of temperature in different solvents. The fitting result of dissolution model from the Apleblat equation is better than that of the λh equation. Positive values of ΔH_d， ΔS_d， and ΔG_d indicate that the dissolving process of DAP-4 are non-spontaneous endothermic.

Abstract:Using droplet microfluidics technology， an aqueous solution of the active agent at a concentration of 0.5% was used as the continuous phase， and an ethyl acetate solution of DAAF was employed as the dispersed phase. DAAF/F2602 composite microspheres were prepared by fluid-focused microchanneling. The effects of two-phase flow rate ratio， concentration of dispersed phase， and type of active agent on particle morphology， particle size， and roundness of DAAF/F2602 composite microspheres were investigated. The optimal process conditions， including a suspension concentration of 4%， a two-phase flow rate ratio of 16∶1 and an active agent of CTAB， were obtained and compared with the aqueous suspension method. The results show that the DAAF crystalline shape of the samples obtained from two preparation methods are unchanged， the impact sensitivity is higher than 100 J， and the friction sensitivity is 0% and the friction sensibility are more than 360 N， indicating that the two samples have good safety performance. Among them， the particle sizes of DAAF/F2602 composite microspheres which obtained by the droplet microfluidization method were in the range of 20.22 to 53.85 μm， which were smaller than that obtained by the aqueous suspension method （121-356 μm）.Furthermore， the particle sizes distribution was observed to be more uniform. Thethermal decomposition exhibited a delayed peak temperature by 6.45 ℃， and the activation energy was increased by 6.12 kJ·mol^-1， which lead to improved thermal stability. The cone angle generated by the stacking of DAAF/F2602 composite microspheres which obtained by the droplet microfluidization method， is 34°. This angle is smaller than that of composite particles obtained by the water suspension method （40°）， which indicate better dispersion property.

Abstract:In order to rapidly analyze the product quality of 2，6-diamino-3，5-dinitropyrazine-1-oxide （ANPZO） and optimize the synthesis process， high-performance liquid chromatography （HPLC） method was developed to quantitatively analyze the purity of ANPZO. The effects of mobile phase composition， elution mode and detector wavelength on the resolution have been studied. The separation of ANPZO and its intermediate 2，6-diamino-3，5-dinitropyrazine （ANPZ） was accomplished by using C18 analytical column with size of 250×4.6 mm and 5 µm. The initial mobile phase composition was 0.1% trifluoroacetic acid and methanol （95∶5， v/v）. The methanol ratio was increased to 100% from 2 min to 7 min after the sample injection. Gradient elution was performed at a flow rate of 1.0 mL·min^-1， the column oven temperature was set at 30 ℃， and detection wavelength was 425 nm. The validation of the developed methods showed good linearity （R²=0.9996）， repeatability （%Area RSD%=0.30%） over the concentration range of 0.1 mg·mL^-1 to 0.6 mg·mL^-1. The limit of detection（signal/noise=3） and quantitation（signal/noise=10） of ANPZO were found to be 20 ng·g^-1 and 67 ng·g^-1， respectively. Therefore， the reported method is accurate， precise and sensitive， which can be used for the quality control of ANPZO.

Abstract:Fused-ring energetic compounds， composed of two or more rings sharing two atoms and one chemical bond， have sizeable π-π conjugate structures and are a kind of popular new energetic materials. The polycyclic coplanar structure of energetic fused rings shows good molecular stability. Furthermore， the coplanar structure is featured with high heat of formation， significant ring tension， and high energetic performance. It can achieve a balance between high performance and molecular stability. With a C—N bond as the common building block， these nitrogen heterocycles have good density， stability， and numerous modifiable sites， which have become a new class of backbones in the field of energetic fused heterocycles. In this paper， the authors review the recent advance of synthesis， detonation properties， stability， and outlook of C—N type fused-ring energetic materials， which will be useful for the energetic community in future studies.

Abstract:The reaction mechanism of intermediate 3，3′-Bis（1，2，4-oxadiazole）］-5，5′-diyldimethanol acetate （BODM） hydrolyzed to 3，3"-Bi（1，2，4-oxadiazole）-5，5"-diyldimethanol （BOD） was investigated by theoretical calculation. The synthesis process was optimized by single factor experiment and orthogonal experiment. The structure and properties of BOD were analyzed by XRD， FTIR， NMR and DSC. It was found that the reaction mechanism was the lone pair electrons in BODM —［O］— formed an OH…O hydrogen bond with H in H₂O， then the O—C bond in —［O］—［C═O］—broke， and the H and OH bonds in H2O formed —OH and —COOH group in —［O］— and —［C═O］—， respectively. and found that the crystal of BOD belong to the monoclinic system， the space group is C2/c， the cell angle α=90°， β=105.361（7）°， γ=90°， the cell volume v=774.9（2） A³， the density ρ=1.698 g·cm^-3. The melting point and decomposition peak temperature were 197.18 ℃ and 278.37 ℃， respectively. The results of single factor experiment showed that with the increase of reaction time and solvent， the yield of BOD increased at first and then became stable. With the increase of reaction temperature， the yield of BOD increased slowly and then decreased rapidly. With the increase of material ratio， the yield of BOD increased first and then decreased. In addition， the optimal process conditions were obtained by orthogonal experiment： BODM hydrolyzed in potassium carbonate methanol solution at 45 ℃ for 8 h， in which the molar ratio of BODM to potassium carbonate was 15∶1， and the yield was 94%. This study provides theoretical basis and experimental reference for scaling up and large-scale production of BOD.

Abstract:In order to improve the safety performance of hexanitrohexaazaisowurtzitane （CL-20）， the CL-20 with self-assembled stacking structures were prepared by the solvent-nonsolvent method using nitrified graphene （NG） as a crystallization inducer. The morphologies， structures， and thermal properties of the stacking structure CL-20 were characterized by field emission scanning electron microscopy （FE-SEM）， X-ray diffraction （XRD）， fourier transform infrared spectroscopy （FT-IR）， and synchronous thermal analyzer （DSC-TG） respectively， and their mechanical sensitivities were tested and analyzed. The results show that under the induction of different content of NG， CL-20 recrystallizes into square flake crystals， and self-assembles and stacks into petal-shaped， spiral-shaped， tower-shaped， and other structures. During the formation of the self-assembled stacking CL-20， the induction effects of NG are reflected in the adsorption effect of its sheet layer on CL-20 and the formation of hydrogen bonds between NG′s active functional groups with CL-20. Compared with the raw CL-20， the thermal decomposition temperature of the self-assembled stacking CL-20 is reduced by about 5 ℃， the maximum thermal decomposition enthalpy is increased by about 33%， and the mass loss is increased from 81% to 99%. The prepared self-assembled stacking CL-20 has a significantly lower mechanical sensitivity than that of the raw CL-20. When the NG content is 0.5%， the self-assembled petal CL-20 prepared by NG induction has the lowest impact sensitivity of 6 J.

Abstract:Data derived from high-accuracy quantum-chemistry calculations plays a significant role in designing， synthesizing， and characterizing energetic compounds. Therefore， constructing a quantum-chemistry database of energetic compounds， which collects high-accuracy quantum-chemistry calculation data， can circumvent massive duplicated calculation research and resource consumption. In addition， such an approach guarantees the quality of data， facilitates in-depth analysis and data mining， and obtains reliable analytical and predictive models for the structures and properties of energetic compounds. This review summarized data related to critical structures and properties of energetic compounds from quantum-chemistry calculations and the development of molecular design using a database and high-throughput virtual screening technique. The design and application of the quantum-chemistry database of energetic compounds were envisioned， including （1） the establishment of calculation standards and prediction models to generate customized data in the field of energetic materials； （2） the construction of an open and shared database to join high-throughput virtual screening； and （3） the development of database management systems to realize data inquiry， acquisition， and data mining. It is hopeful to provide insights for the design and practical application of the quantum-chemistry database of energetic compounds.

Abstract:The spheroidization of energetic materials can significantly improve the processing and application properties of explosive crystals. Based on the current research on spheroidization technology of typical energetic materials both in China and abroad， the research progress of spherical single crystals， spherical agglomerates and spherical branched crystals are reviewed from the perspective of crystallization strategy. The crystallization process， spheroidization mechanism and desensitization effect of spherical products are emphatically introduced. It is showed that spherical products have the virtues of good flowability， high bulk density and low sensitivity， and have great potential in explosive applications. Combining crystal engineering thinking， it is suggested to construct the crystallization database of typical energetic materials， strengthen online process monitoring， improve model calculations and multidisciplinary cross study， thus providing guidance for precise regulation and industrial production of spherical crystallization process of energetic materials.

Abstract:To improve the stability of aluminum hydride （AlH₃）， three kinds of embedded-coated AlH₃@Al@xAP（AHAPs） energetic composite particles were prepared by the combination of using acoustic resonance and spray drying technology. The mass ratios of AlH₃@Al and AP were 9∶1（AHAPs-10%）， 7∶3（AHAPs-30%）， and 1∶1（AHAPs-50%）， respectively. The morphologies and structures of the AHAPs and their condensed combustion products were characterized by SEM， EDS， and XRD. The thermal reactivity and stability of the prepared samples were comparatively studied by TG-DSC analysis and vacuum stability tester （VST）. Results show that AHAPs energetic composite particles could not only improve the stability of AlH₃ but also promote the decomposition of AP. With the increase of AP content， the initial decomposition temperatures of AlH₃ are increased by 8.5-11 ℃， and the peak temperature at high-temperature decomposition stage of AP is decreased by about 80 ℃. Compared with the total decomposition time of pure AlH₃（1006 min）， the decomposition time of AHAPs-50% composite particles extend to 1518 min， which corresponds to a 50.9% increment. In addition， the reaction heat of embedded-coated composite particles AlH₃@Al/63.5% AP reaches 9125.6 J·g^-1， which is 1054.1 J·g^-1 higher than that of mechanically mixed samples， and the particle sizes of the condensed combustion products appear to be finer， indicating that their combustion become more complete and the combustion efficiency is greatly enhanced.

Abstract:A series of ionic liquids based on N，N-（dimethylcyclopropyl）cyclopropylamines as cations and dicyandiamide/cyanoborohydride as anions were synthesized by using the three-member carbocyclic ring as the tension energy structural unit. The structures of ionic liquids were confirmed with the characterizations such as nuclear magnetic （NMR）， infrared spectroscopy （IR） and high-resolution mass spectrometry （HRMS）. Their physicochemical properties （e.g.， melting point， thermal decomposition temperature， density， viscosity， heat of formation， specific impulse， and ignition delay time） were measured and/or calculated in detail. The results demonstrate that all ten synthesized ionic liquids show hypergolicity with white fuming nitric acid （WFNA）， and the cyanoborohydride based ionic liquids have the shorter ignition delay times than the corresponding dicyandiamide ionic liquids. More strained ring groups lead to the higher heats of formation （0.87-1.96 kJ·g^-1）， and the compact stacking of small ring structures makes an increase in the densities （1.01-1.18 g·cm^-3） of the ionic liquids. Therefore， the strained ring-based hypergolic ionic liquids exhibit the higher density-specific impulse （436.7-454.4 s·g·cm^-3）. The introduction of high-energy strained ring groups in the molecular structures provides a way to improve the energy densities of hypergolic ionic liquids.

Abstract:In order to solve the problems of high energy consumption， difficulty in particle size control and serious pollution in the preparation of nano-aluminum powder. green and safe preparation of nano-aluminum powder is fulfilled by liquid chemical method through adding diisobutyl aluminum hydride （DIBAL） to aluminum chloride-1-ethyl-3-methylimidazole chloride（AlCl₃-EMIC） ionic liquid with the molar ratio of 2∶1. By means of X-ray diffraction （XRD）， nano-particle size detection， transmission electron microscopy （TEM）， scanning electron microscopy （SEM）， energy dispersive spectrum of X-ray （EDS） and linear scanning voltammetry （LSV）， the nano-aluminum powder was characterized and its growth process and reaction mechanism were explored The results show that when DIBAL concentration is 0.25 mol·L^-1 and reaction time is 0.5 min， the non-agglomerated aluminum powder with uniform particle size of 40-100 nm is obtained， which is more uniform than the one obtained by other liquid chemical methods. The abnormal growth of aluminum powder is observed at different DIBAL concentrations， which is related to the Ostwald ripening. In addition， the AlCl₃-EMIC ionic liquid is not only the reaction medium， but also the Al source of the nano-aluminum powder.

Abstract:Refined 3-nitro-1，2，4-triazol-5-one （NTO） product were prepared by spray drying technology to improve the morphology and reduce the particle size. Acetone was used as the experimental solvent. The effects to inlet temperature， inlet flow rate， feed rate and precursor mass concentration on the morphology and particle size of the refined NTO were investigated， and the optimal spray drying process parameters was selected. The surface morphology， molecular structure and thermal stability of refined NTO products were characterized by scanning electron microscopy （SEM）， X-ray diffraction （XRD） and fourier transform infrared spectroscopy （FT-IR）， and synchronous thermal analyzer （TG-DSC）. The results show that the sphere-like NTO with good morphological， stable crystal structure， narrow particle size distribution range and an average particle size of 1.2 μm can be obtained when the inlet temperature is 60 ℃， the inlet gas flow rate is 357 L·h^-1， the feed rate is 3 mL·min^-1， the NTO precursor concentration is 16.57 mg·mL^-1. Compared with the feedstock， the thermal decomposition activation energy of the refined NTO was enhanced by 41.7 kJ·mol^-1， and the thermal explosion critical temperature was increased by 10.4 ℃， which has better thermal stability.

Abstract:Triazole-based energetic compound is a new class of energetic materials with the features of high heat of formation， high nitrogen content and good thermal stability. In this paper， the latest research achievements on synthesis of more than 40 series of energetic compounds based on mono-triazole， bis-triazole， pyrazole-triazole， oxadiazole-triazole and tetrazole-triazole were reviewed， and the performances of some compounds were introduced in detail. It is showed that designing new triazole-based energetic compounds based on structure-performance relationship and balancing energy and safety are the effective strategy to develop high energy and insensitive energetic compounds. On this basis， design and synthesis of cage triazole-based energetic compounds are the promising developing direction. The application study of existing triazole-based energetic compounds with outstanding overall performance is proposed.

Abstract:The introduction of fluorodinitromethyl group into energetic molecules can not only improve oxygen balance， density and explosive performance， but also increase thermal decomposition temperature and reduce sensitivity. The construction of energetic compounds containing fluorodinitromethyl groups has become a hot research topic in the field of high energy dense and insensitive materials. By reviewing the energetic compounds containing fluorodinitromethyl groups in the past two decades， we analyzed and compared the molecular structures， summarized the synthesis methods of fluorodinitromethyl-containing compounds， physicochemical and explosive properties of these compounds， providing some references for the molecular design and synthesis of novel fluorodinitromethyl substituted compounds.

Abstract:To explore low sensitivity and environmental-friendly energetic combustion catalysts， three new energetic copper complexes， ［Cu（NH₃）₄（DN）₂］， ［Cu（IMI）₄（DN）₂］， ［Cu（ATO）₄］（DN）₂ were synthesized. Ammonium dinitramide （ADN） was used as a precursor to prepare dinitramide acid （HDN） by ion exchange reaction， and the resultant solution reacted with basic copper（Ⅱ） carbonate continually to produce copper（Ⅱ） dinitramide， which reacted further with nitrogen-rich ligands （ammonia， imidazole， 4-amino-1，2，4-triazole-5-one）. The structures of the three complexes were characterized accurately by X-ray single crystal diffraction， infrared spectroscopy and elemental analysis. Their thermal stability， hygroscopicity， sensitivities toward impact （IS）， friction （FS） and electrostatic discharge （ESD） were investigated. Furthermore， the effect of ［Cu（IMI）₄（DN）₂］ towards the burning rate of propellants were performed. Results show that the thermal stability of three complexes can meet the application requirement of solid propellants， and the initial decomposition temperatures are all higher than 140 ℃. The hygroscopicity of the complexes were improved obviously， which could be as low as 2%-5% of the precursor ADN. ［Cu（IMI）₄（DN）₂］ has the lowest sensitivity （IS 28.6 J， FS 0%， ESD 185 mJ） of the three complexes. With 4% of ［Cu（IMI）₄（DN）₂］， the burning rate of the basic formula propellants was increased by 27.7%， which was expected to be used as low sensitivity burning rate catalyst in high burning rate solid propellants.

Abstract:Polycyclic structures with high nitrogen content exhibit great potential in balancing the contradiction between energy and safety of energetic compounds. As an important structural unit for the design of high nitrogen content polycyclic energetic molecules， furazan has the characteristics of good stability， high nitrogen content， high positive enthalpy of formation and good oxygen balance tendency. The design and synthesis of polycyclic energetic compounds containing furazan unit have become a focus that has been studied extensively and deeply in the research field of energetic materials. This review article summarized and evaluated the molecular structures， synthetic methods， physicochemical properties of furazan based polycyclic energetic compounds. Meanwhile， the potential applications of these compounds in high energy and low sensitivity explosives， heat-resistant explosives and primary explosives were also prospected， providing a reference for the design and synthesis of new polycyclic energetic compounds.

Abstract:A novel cage-like energetic compound， 6-nitro-2-oxa-6-azaadamantane-4，8-diol dinitrate， was synthesized from 1，5-cyclooctadiene via oxidative cyclization， O-acylation， elimination， epoxidation， aminolysis and nitration with an overall yield of 20.7%. The single crystal structure of 6-nitro-2-oxa-6-azadamantane-4，8-diol dinitrate was obtained by X-ray single crystal diffraction. Its structure was characterized using NMR， IR， and elemental analysis. Thermogravimetric analysis （TG） and differential scanning calorimetry （DSC） were used to study the thermal stability of the target compound. Density functional theory method was used to study the detonation properties of the target compound. Result show that it has a density of 1.75 g·cm^-3， a thermal decomposition temperature of 184 ℃， a detonation velocity of 7730 m·s^-1， and a detonation pressure of 26.07 GPa.

Abstract:For the problems of low nitrification yield and the use of highly toxic substances in the synthesis of high-energy oxidant 1，4-bis（trinitromethyl）-3，6-dinitropyrazole［4，3-c］pyrazole （ONPP）， a new synthetic process of ONPP was developed. The single crystal of ONPP was cultivated by slow evaporation from an ethyl acetate solution. The energy levels of different formulations based on ONPP were estimated. In the presence of base and phase transfer catalyst Bu₄NBr（TBAB）， 3，6-dinitropyrazole［4，3-c］pyrazole （DNPP） reacted with bromoacetone to introduce two acetone groups on pyrazole ring. Followed by nitrating with HNO₃/H₂SO₄/P₂O₅， ONPP was obtained in the total yield of 31%. Compared with the literature （10.4% total yield from two steps）， the yield of new synthetic route from DNPP increase by nearly three times. Meanwhile the use of highly toxic butenone is avoided， which is more suitable for large-scale production. The crystal structure of ONPP belongs to the monoclinic crystal system， P2₁/c space group. Its crystal density is 1.983 g cm^-3 at 293 K. Through the energy estimation of HTPB （10%）， Al （20%） and oxidizer （70%） formulations， the energy level is optimal when ONPP （40%） and AP （30%） are used together as oxidizers， which is significantly higher than the formulation energy levels when they used as single oxidant.

Abstract:Energetic molecules with cage-like backbones， owning additional strain energy and stability， are potential candidates for optimizing the long-known contradiction between high energy density and low sensitivity of energetic materials. However， the reaction mechanism of caged energetic materials under shock compression is still unclear. Here， a series of ab initio molecular dynamics calculations were conducted to simulate the early decay of typical caged energetic compounds when compressed by shock waves of 8 to 11 km·s^-1，and the studied compounds included octanitrocubane （ONC）， hexanitrohexaazaisowoodethane （CL-20）， 4，10-dinitro-2，6，8，12-tetraoxa-4，10-diazatetracyclododecane （TEX）， and the reference plane system triaminotrinitrobenzene （TATB）. The shock sensitivity of the four studied systems was calculated as ONC > CL-20 > TEX > TATB， which is in good agreement with reference experimental shock/impact sensitivity tests. The reaction initiation mechanism was revealed （i） the presence of electron-rich oxygen/nitrogen elements increases electron delocalization over the cage and the proper degree of freedom of the covalent bonds confers them additional elastic deformation capacity upon shock stimulus， both enhance the structural stability of hetero-cage， （ii） the dissociation of the nitro groups takes precedence over the collapse of the hetero-cage， which can delay the reaction process and reduce the shock sensitivity， and （iii） intermolecular hydrogen bonds （HB） is highly plastic deformable and enriched HB can delay the onset of reactions by buffering shocks. The current study proposed that the hetero-cage backbone with enhanced electron delocalization effect and proper degree of freedom， and the enriched intermolecular hydrogen bonding interactions could reduce the shock wave sensitivity， thereby providing theoretical guidance for the rational design of novel insensitive energetic materials.

Abstract:In order to explore new energetic material with both good thermal stability and high safety performance， 4，8-di（2，4，6-trinitro-3，5-diaminophenyl）difurazanopyrazine （NADFP） was synthesized by substitution reaction using 1-chloro-2，4，6-trinitro-3，5-diaminobenzene and 4H，8H-difurazanopyrazine as raw materials. Its structure was characterized by nuclear magnetic resonance （¹H and ¹³C spectrum）， infrared spectroscopy and element analysis. The single crystal of NADFP·DMF was obtained by solvent evaporation method， and the crystal structure was determined by single crystal X-ray diffraction. Results show that NADFP·DMF belongs to monoclinic system， space group P2₁/c， a=7.854（3） Å， b=18.466（6） Å， c=11.093（3） Å， ρ=1.640 g·cm^-3. The inter-/intramolecular interactions were calculated by Hirshfeld surfaces analysis with hydrogen bond interactions accounting for 53.5%. The thermal behavior of NADFP was studied by DSC and TG/DTG methods， which show that its decomposition peaks are 337.2 ℃ and 368.8 ℃. The theoretical detonation performances and mechanical sensitivities of NADFP were investigated. The measured density is 1.81 g·cm^-3， the solid formation enthalpy is 827.1 kJ·mol^-1， the calculated detonation velocity and pressure are 7968 m·s^-1 and 36.0 GPa， respectively. The impact sensitivity is above 40 J， and the friction sensitivity is above 360 N. The overall performance of NADFP is obviously better than that of traditional heat-resistant explosive 2，2′，4，4′，6，6′-hexanitrostilbene.

Abstract:The eutectic mixtures of 2，4，6-trinitro-3-bromoanisole （TNBA） and 1，3，3-trinitroazetidine （TNAZ） with different mass ratios were prepared by the electrostatic spray method. T-X and H-X phase diagrams were drawn according to the differential scanning calorimetry （DSC） curves of the eutectic mixtures to obtain the mass ratio of the lowest eutectic. Scanning Electron Microscopy （SEM）， Energy Dispersive Spectroscopy （EDS）， High Performance Liquid Chromatography （HPLC）， X-ray Powder Diffraction （XRD）， Infrared （IR）， X-ray Photoelectron Spectroscopy （XPS）， DSC， and thermogravimetry-mass （TG-MS） spectrometry were used to determine the morphology， component content， element distribution， crystal structure and thermal decomposition properties of the lowest eutectic. And the mechanical sensitivity， thermal sensitivity and detonation performances of the lowest eutectic were tested and theoretically calculated. The results showed that 60.95∶39.05 is the optimal mass ratio of TNBA/TNAZ lowest eutectic mixture； the microscopic morphology has no sharp edges and corners； the component proportion is the same as before electrostatic spraying； the surface elements are evenly distributed； and the crystal structure is basically the same as that of the raw materials. The eutectic temperature is 350.18 K， which is 22.72 K and 24.82 K lower than that of raw materials TNBA and TNAZ. The thermal decomposition reaction rate constant （k）， activation enthalpy （ΔH^≠）， activation energy （E_K）， activated Gibbs free energy （ΔG^≠）， and activation entropy （ΔS^≠） of the lowest eutectic are 0.33 s^-1， 60.10 kJ·mol^-1， 64.44 kJ·mol^-1， 135.21 kJ·mol^-1， and -143.78 J·（mol∙K）^-1， respectively. The impact sensitivity （H₅₀）， friction sensitivity （FS）， and 5s explosion temperature of the lowest eutectic mixture are 42 cm， 20%， and 558 K， respectively. Its detonation performance （OB=-34.83%，Q=5101.78 kJ·kg^-1，V_D=7598.37 m·s^-1） is between TNBA and TNAZ. The main detonation products are N₂、C（d）、CO、CO₂ and H₂O.

Abstract:As a kind of clean energy， microwave is widely used in energetic materials due to its unique penetrability and high safety， which can interact with energetic materials in volume. The application of microwave in the testing of energetic materials， microwave assisted synthesis of energetic materials， excitation of energetic materials and enhancement of propellant combustion were summarized. The mechanism of microwave-assisted synthesis of energetic materials is not clear， the absorption materials introduced in microwave sensitized explosives is relatively single， and the microwave enhanced combustion is only suitable for some propellants were pointed out. The future development directions were put forward： expanding the types of absorbing materials， activating non-metallic energetic materials by microwave ignition of nano-thermites， and realizing the dexterity and convenience of microwave devices.