Abstract:For achieving engineering application of pentazolium anionic energetic materials， it is necessary to realize large-scale production of 3，5-dimethyl-4-hydroxyphenylpentazole （HPP） as the precursor of pentazole. The pilot synthesis techniques of HPP were performed based on accessibly lab-leveled method using 10 L and 100 L reactors for scale-up experiments. The dropping time of aqueous solutions of sodium nitrite and sodium azide， the purity and the feeding mass of 3，5-dimethyl-4-hydroxyaniline hydrochloride （DAC）， on the production of HPP were investigated. Results indicate that HPP production increases with the increasing of the total dropping time of sodium nitrite aqueous solution and sodium azide aqueous solution. After a certain value， the production of HPP remains. The purity of DAC affects the HPP production significantly that the production increases with the increasing of purity. With the scale up， HPP production increases along with the reducing of production ratio. With the feeding mass of DAC reached to 6 kg， a batch of product increased to 11.5 kg as well as the production rate decreased to 1.91.

Abstract:In order to synthesize high-purity 3，5-diamino-2，4，6-trinitrochlorobenzene （DATNCB）， the synthesis route screening and process optimization of DATNCB were studied with 1，3，5-trichloro-2，4，6-trinitrobenzene （TCTNB） or picric acid （2） as raw materials， respectively. The structure of the product was characterized by IR， NMR and MS； the thermal behavior of DATNCB was studied by DSC-TG； the purity of DATNCB was analyzed by HPLC. The results show that： the best synthetic route of DATNCB is starting from picric acid， then by via VNS amination followed by chlorination. The total yield is 39.2%. The highest yield of 3，5-diamino-2，4，6-trinitrophenol （3） was 74.8% when VNS amination temperature was 90 ℃ and post-treatment pH value was 3； the highest yield of DATNCB was 52.4% when phosphorus oxychloride/N，N-dimethylaniline was used as the chlorination reagent， the reaction temperature was 80 ℃ and the reaction time was 10 h. The melting point of DATNCB is 224.0 ℃. There is only one weight loss stage in the range of 179.7-270.9 ℃ and the weight loss rate is 91.6%； the peak decomposition temperature is 256.1 ℃. The purity of DATNCB reach 97.09% without further purification， and up to 99.8% after recrystallization with ethyl acetate/petroleum.

Abstract:High-energy-density hydrocarbon fuels are important aerospace power source， which mainly developing direction is high-energy and green， especially under the requirements of low carbon and sustainable development， the green synthesis of high-energy-density hydrocarbon fuel becomes essential. The green synthesis technology of high-energy-density hydrocarbon fuel has been reviewed. Compared with traditional synthesis of JP-10 （exo-THDCPD） and Adamantane， the advanced synthesis for fuel is improved by changing the synthesis route or using green catalysts such as solid acids and ionic liquids. Using biomass as feedstock is another strategy for green synthesis， covering terpenoids and lignocellulose-derived platform molecules such as cyclic ketones/alcohols， furanic aldehydes/alcohols， etc.， and the alternative fuels such as bio-based RJ-4（endo-THDMCPD and exo-THDMCPD） and JP-10 have been synthesized. In addition， the photocatalytic technology is used to synthesis of fuel with high tension and polycyclic structures from the perspective of green synthesis process view point， an outlook on further development of high-energy-density hydrocarbon fuel is also given. This review article will be helpful to explore and develop better approach and process for the synthesis of high-energy-density hydrocarbon fuel and upgrade for advanced aerospace vehicles.

Abstract:Bridged nitrogen-rich heterocyclic energetic compounds are of the rich diversity， good thermal stability and excellent energy density. They are potential materials with high energy density and have been widely studied and reported by scholars all over the world. Among them， the imino group （—NH—）， which acts as bridged unit， can not only improve the enthalpy of formation and energy density， but also reduce the sensitivity by the formation of hydrogen bonds through the bridged imino group， thereby constructing high-energy and low-sensitivity energetic materials. This paper introduces the research progress of imino-bridged nitrogen-rich heterocyclic energetic molecules and their salts， and reviews the preparation methods， physicochemical properties and detonation properties of these energetic compounds， the future development potential and research trend of imino-bridged nitrogen-rich heterocyclic compounds are prospected， so as to provide a reference for the design and synthesis of imino-bridged energetic compounds.

Abstract:4H-［1，2，3］Triazolo［4，5-c］［1，2，5］oxadiazole 5-oxide （TODO）hydroxylamine salts and TODO amine salts were synthesized via nitration， cyclization and salt-forming reaction using 3，4-diaminofuran. At the same time， an energetic eutectic（HATODO/ATODO cocrystal） was synthesized by TODO hydroxylamine salts（NH₃OH⁺C₂H₅O^-）and TODO amine salts（NH₄⁺C₂H₅O^-）as raw materials. Its structure was characterized by SXRD，FT-IR and NMR， and the thermal decomposition was studied by TG-DSC. The mechanical sensitivities were tested according to the GJB772A-97 method and the detonation performance was calculated. Results show that the structure of the HATODO/ATODO cocrystal belongs to the monoclinic crystal system， the P2₁/c space group， a=8.5202（3） Å， b=10.3870（4） Å，c=13.4481（4）Å， α=90°， β=102.0510（10）， γ=90°， V=1163.92（7） ų， Z=4.TODO hydroxylamine salts initial decomposition temperature is about 147.9 ℃， TODO amine salts initial decomposition temperature was about 181.3 ℃， whereas the initial decomposition temperature of energetic HATODO/ATODO cocrystal is about 151.2 ℃. The sensitivities of HATODO/ATODO cocrystal is comparable to ADN. The calculated detonation velocity and pressure of HATODO/ATODO cocrystal is 8462 m·s^-1 and 32.07 GPa.

Abstract:

Abstract:Iodine-rich compounds are a new type of bactericidal materials developed in recent years. Gaseous products comprised of large amounts of iodine or iodine-containing components are released can be used as strong biocides during the progress of decomposition or explosion of iodine-rich compounds. It has the advantages of short response time， good flexibility， high sterilization efficiency， and can adapt to the needs of complex environment. In this review， we summarized the iodination methods of preparing five-member or six-member nitrogen heterocycles by using I₂/KI， I₂/oxidants， NIS or ICl， and the range of application， advantages and disadvantages of different iodide methods were compared and analyzed， It is pointed out that the preparation of iodine-rich energetic compounds in the future should focus on improving the atom economy of iodine and the green and friendly synthesis process. It is hoped that this review will provide guidance for the design， synthesis and large-scale preparation of new iodine-rich energetic compounds in the future.

Abstract:High tension bonds or high-energy bonds are important elements in the formation of disruptive energetic materials， but it"s hard to form and easy to break，. Their construction has always been a difficult problemin the field of chemistry and energetic materials. By using the unique internal space of molecular cages to “assist” the construction of such chemical bonds provides a feasible route for related research， and has been put into practice. This review summarized “confinement effect”， weak interaction， electron transport and other characteristics of molecular cages. It is discussed that it can prevent oxygen oxidation of P₄ and other high-tension materials， stabilize aryl pentazoles and other high active substances， reactants such as NaN₃ to accelerate the reaction， change the reaction path. The roles of molecular cages in these processes， such as “firewall”， “stabilizer”， “accelerator”， “channel remover” and others， were reviewed， which provided references for the preparation of novel energetic compounds such as TdN₄ and the study of controllable energy release . At the same time， it also points out the key direction of future research： design and synthesis of new and efficient molecular cages. developing good characterization methods and means of molecular cage complex. Enhance the composite and release of multi-environment responsive molecular cages and energetic materials.

Abstract:In order to study the performance of 3，3''-bi（1，2，4-oxadiazole）-5，5''-diylbis（methylene）dinitrate （BOM）， the sample was prepared by using the melting casting process and its the detonation velocity was measured. The thermal safety of the BOM casting process was studied by the thermal decomposition and constant temperature test. The solidification properties of BOM were studied by macroscopic solidification molding and microscopic solidification crystallization test. The mechanical properties of the BOM casting were studied by compressive and tensile tests. The detonation velocity and detonation heat properties of BOM/HMX/Al melt-cast explosive system were analyzed by detonation performance calculation. The results show that the natural solidification density of BOM is 1.726 g·cm^-3 and the detonation velocity is 7679 m·s^-1. The peak temperature of BOM decomposition is 213.8 ℃， and the calculated critical temperature of thermal explosion is 190.7 ℃. There is no discoloration and smoke during the constant temperature heating， which shows satisfactory thermal safety of the melt-casting process. The solidification defects of BOM were concentrated in the feeding area at the top of the casting， The volume shrinkage rate of natural solidification was 15.7%， and the forming density was 94.7% of the theoretical density， indicating good solidification and forming performance. The compressive strength of the casting is 6.21 MPa and the tensile strength is 1.89 MPa. In the BOM/HMX/Al melt-cast explosive system， the detonation velocity decreases linearly with the increase of Al content. When the Al content is less than 24%， the detonation heat increases gradually with the increase of Al content. When the Al content is more than 24%， the detonation heat is related to the ratio of BOM and HMX in the formula， and the ratio of BOM and HMX system needs to be adjusted to meet the optimal Al/O ratio of the formula.

Abstract:A novel melt-cast energetic compound bis（dinitromethyl-ONN-azoxyfurazanyl）furazan （BDNAF） was synthesized using 3，4-bis （3′-aminofurazal-4′-yl）furazan （BATF） and 2，2-dimethyl-5-nitro-5-nitroso-1，3-dioxane （DMNNDO） as starting materials via oxidation coupling， hydrolysis， bromization， reduction and nitration five-step reactions. The structures of the intermediates and the target material were fully characterized by infrared spectrum（IR）， nuclear magnetic resonance（NMR） and elemental analysis（EA）. The thermal behaviors of intermediate compound 3，3'-bis（nitromethyl-ONN-azoxyfurazanyl）furazan （BNAAF） and target compound BDNAF were investigated based on differential scanning calorimetry（DSC） measurement， and the physicochemical properties and detonation performances of BNAAF and BDNAF were estimated by Gaussian 09 program and Explo 5（v. 6.04）. Results show that the intermediate compound BNAAF directly decomposed at 106.4 ℃ without melting process， and the calculated density of BNAAF is 1.82 g·cm^-3， the detonation velocity is 8298 m·s^-1， and the detonation pressure is 29.0 GPa. The melting point of the target compound BDNAF is 95.4 ℃， the first decomposition point is 170.5 ℃ at the heating rate of 10 ℃·min^-1， and the theoretical density of BDNAF is 1.91 g·cm^-3， the detonation velocity is 9005 m·s^-1 and the detonation pressure 35.9 GPa， which revealed that BDNAF is a promising melt-cast explosive.

Abstract:Cocrystal is composed of different neutral components through intermolecular non-bond interactions at molecular level and it has fixed ratio and particular structure. Cocrystallization technology is a novel method for ameliorating properties of energetic materials and it has wide development prospect and application value. It can decrease the sensitivity， improve the mechanical properties， thermal performance， and energy density of energetic materials. The research progress of preparation and application of energetic cocrystals was summarized， including the current research status， preparation method， characterization methods， and formation mechanism. The existing problems of energetic cocrystals were introduced： first， the properties of some cocrystal explosives need to be further improved； second， the preparation of cocrystal requires harsh conditions with low product yield； third， the characterization and test methods lack variety. The further development direction of cocrystal explosives were pointed out： strengthen the research of multiple components energetic cocrystals， improve the technologies to increase the yield， investigate the crystallization dynamics behavior to seek for the best cocrystallization conditions， and look for effective means to characterize the cocrystal structure.

Abstract:Using 4，5-dicyano-2-aminoimidazole as raw material， 4，5-Bis-（chloro-dinitro-methyl）-2-diazoimidazole was prepared through three-step reactions of oximation， chlorination， diazotization. The structure was characterized by X-ray single crystal diffraction analysis， Fourier transform infrared spectroscopy（FT-IR）， nuclear magnetic resonance spectroscopy （1H NMR， 13C NMR） and high resolution mass spectrometry（HRMS）. The thermal properties were studied by differential scanning calorimeter and thermogravimetric analyzer. Its structure was optimized using Gaussian09 and its performance was estimated using Explo5 v6.01.. The results show that the crystal of 4，5-Bis-（chloro-dinitro-methyl）-2-diazoimidazole belongs to the triclinic P1 space group. The unit cell parameters are a=6.6196 （10） Å， b=8.1685（13） Å， c=13.0272（19） Å， V=666.96（18） Å， α=100.166（4）°，β=102.560（4）°， γ=97.153（5）°， Z=2， F（000）=368； D_c=1.848 g·cm^-3. Its thermal decomposition temperature is 122.14 ℃.The theoretical detonation velocity is 8574 m·s^-1 and the theoretical detonation pressure is 32.8 GPa. According to the BAM standard method， the impact sensitivity is 4 J and the friction sensitivity is 100 N.

Abstract:Planar heteroaromatic compounds containing amino and nitro functional groups usually have excellent detonation performances. Hereby， the ─NH─ bond bridging two high-nitrogen fused rings was adopted aiming at constructing a nitrogen-rich energetic compound with a planar structure. The resulting compound is expected to have a regular packing in crystal and favorable detonation performance and stabilities. Reaction of 2，6-diamino-3，5-dinitropyrazine （2） with K₂CO₃ gives rise to 6-（2，6-diamino-3，5-dinitropyrazine）-1，2，4-triazole［4，3-b］［1，2，4，5］tetrazine （3） in a high yield of 81.3%. Compound 3 was characterized by NMR， IR， single crystal X-ray diffraction. The thermal decomposition process of 3 was studied by differential scanning calorimetry （DSC）， and its decomposition temperature （onset） is as high as 254.6 ℃. The detonation performances of 3 （D=7568 m·s^-1， P=23.5 GPa） were calculated by Gaussian 09 and Explo5 software.

Abstract:4-hydroxy-3，5-dinitropyrazole（H-DNOP， 2） was synthesized from 3，5-dinitro4-bromopyrazole（1） by hydrolysis and neutralization reaction. Three kinds of ionic energetic compounds （3-5） of DNOP were designed and synthesized by using its acidity. The structures of compounds 3-5 were characterized by FT-IR， NMR spectrum， elemental analysis as well as single-crystal X-ray diffraction， and their thermal stabilities were investigated by differential scanning calorimetry and thermogravimetry （DSC-TG）. The maximum decomposition temperature of hydrazine salt （3） was T_d=210.3 ℃. The impact sensitivity and friction sensitivity were measured by BAM method， while the detonation parameters were predicted based on the isodesmic reactions and the Kamlet-Jacobs equation. The results show that the measured impact sensitivity and friction sensitivity of the threecompounds 3-5 are all 36 J and 360 N， which are less sensitive than those of TNT（IS=15 J，FS=353 N） and RDX（IS=7.4 J，FS=120 N）. The theoretical detonation velocities of the three compounds are 7758-8288 m·s^-1， and the detonation pressures are 26.06-29.96 GPa， respectively.

Abstract:In order to obtain energetic materials with excellent performance， a new type of energetic ionic salt 4-hydroxy-3，5-dinitropyrazole guanidine salt （DNPOG） was synthesized by nitration， hydrolysis， acidification and salt formation reaction with 4-chloropyrazole as raw material. The structure was characterized by FTIR， NMR and EA analysis. The crystal structure of DNPOG was triclinic with space group P-1， relative molecular mass M_r=233.17 g·cm^-1， a=4.8958（5） Å， b=8.1933（8） Å， c=11.9669（11） Å， Z=2， and crystal density D_c=1.750 g·cm^-3. The contribution of hydrogen bond and π-π conjugation in DNPOG to the intermolecular interaction force was calculated and studied， and the hydrogen bond accounted for 47%. The thermal decomposition characteristics were investigated by differential scanning calorimetry （DSC） and thermogravimetry （TG）. The peak temperature of the first decomposition was 212.5 ℃. The detonation and safety properties of DNPOG were studied. The detonation velocity is 7871 m·s^-1， the detonation pressure is 23.8 GPa， the formation enthalpy is -160.2 kJ·mol^-1， the impact sensitivity is 20 J， and the friction sensitivity is 240 N. The results show that DNPOG is layered accumulation， with good thermal stability and low sensitivity， which is a kind of low sensitivity explosive with excellent performance.

Abstract:Using 1，4-dihydrazide succinate as raw material， 1，2-bis（3，3"-dinitroamine-1H-1，2，4-triazol-5-yl）ethane monohydrate （1） was synthesized by the one-pot “MNNG ring method”. And the synthetic conditions of this reaction were carefully optimized. The corresponding 1，3-propanediamine salt （2） was obtained through the reaction of compound 1 and 1，3-propanediamine. The detailed single crystal structure of compound 2 was determined by X-ray single crystal diffraction. FT-IR， NMR and elementary analysis were used to characterize the structures of compounds 1 and 2. Moreover， the thermal properties of compounds 1 and 2 have been studied by TG-DSC. The results showed that the initial decomposition temperature of compounds 1 and 2 are 184 ℃ and 214 ℃， respectively. The main detonation parameters of compounds 1 and 2 were calculated by using EXPLO5 （v6.02） software. The calculated detonation velocity of compound 1 is 8602 m·s^-1 and its calculated detonation pressure is 28.10 GPa. For compound 2， the calculated detonation velocity and detonation pressure are 7740 m·s^-1 and 19.10 GPa， respectively. Furthermore， their mechanical sensitivities were tested by BAM sensitivity test. The impact sensitivity of compound 1 is 35 J and its friction sensitivity is 108 N. The impact sensitivity of compound 2 is greater than 40 J， and its friction sensitivity is more than 360 N.

Abstract:2，4，8，10-Tetranitro-benzopyrido-1，3a，6，6a-tetraazapentalene （NBTTP） was synthesized from 1H-benzotriazole and 2-chloro-3-nitropyridine via displacement， cyclization and nitration.The structure of NBTTP was characterized by FTIR and NMR. In addition， the reaction condition of cyclization was optimized. Its thermalbehavior was analyzed by TG-DTG， while its thermal decomposition behavior， kinetic parameters and thermodynamic parameters were obtained by DSC. The results shows that the highest yield was up to 83.44%， when the molar ratio of triethylphosphite and the BTP was 3∶1. NBTTP presents a main single exothermal event with initial at around 388.79 ℃ and maximum at around 406.23 ℃. Its non-isothermal kinetics equations of thermal decomposition may be described as dα/dt=（6.36×10¹⁴/β）（1-α）exp［-2.34×10⁵/（RT）］. The entropy （ΔS^≠）， enthalpy （ΔH^≠）， free energy （ΔG^≠） and self-accelerating decomposition temperature （T_SADT） were 23.60 J·mol^-1·K^-1， 228.97 kJ·mol^-1， 213.46 kJ·mol^-1 and 655.11 K， respectively.

Abstract:3， 4-bis（3-cyanofurazan） furazan oxide（BCTFO） was synthesized from 3， 4-dicyanofurazan as raw material by multistep functional group transformation of cyanide. The structure of BCTFO was characterized by IR， ¹³C and ¹⁵N NMR and elemental analysis. Combined with the theoretical simulation of GIAO method， the attribution of ¹³C NMR and ¹⁵N NMR spectra was completed. The single crystal of BCTFO was cultivated for the first time， which belongs to monoclinic， C2/c space group. The unit cell parameters are a=19.742（4） Å， b=8.851（2） Å， c=29.275（7） Å，V=4951.3（19） ų，Z=8， ρ=1.75 g·cm^-3， F（000）=2600， S=1.043， R₁=0.0491， wR₂=0.1375. Based on the determined density （ρ=1.76 g·cm^-3） and calculated enthalpy of formation （Δ_fH（s）=806.7 kJ∙mol^-3）， the detonation velocity （D） and detonation pressure （P） of the BCTFO are estimated to be 8086 m·s^-1 and 27.3 GPa by using Explo5（V6.04）. Differential scanning calorimetry （DSC） and thermogravimetric analyzer （TG） were used to study the thermal decomposition process of BCTFO. The peak temperature of thermal decomposition was T_dec=235.4 ℃. The sensitivity of BCTFO was measured according to BAM standard method， the impact sensitivity is 16 J and the friction sensitivity is 330 N.

Abstract:The azo functionality is not only a bridging block， but also can generally increase the density and heat of formation of energetic nitrogen-rich heterocycles. Therefore， building new energetic materials through the bridging method has gradually become a research hotspot in this field. This article reviewed synthesis method， physical and chemical properties and detonation properties of azo-bridged nitrogen-rich heterocycles focusing on azoles and azines from C—NH₂ and N—NH₂ oxidative couplings. This review will provide some references for the research and development of new azo-bridged nitrogen-rich heterocycles.

Abstract:Gem-dinitro group is an attracting moiety in designing novel high energy density compounds due to their high density and oxygen content comparing to the nitro group. The planar structure of gem-dinitro group is beneficial to improve the density， oxygen balance and detonation properties when cooperating with nitrogen-rich heterocycles. In this review， the method of preparing gem-dinitro salts from different precursors was listed， the advantages of using N₂O₄ or N₂O₅ or mixed acid as the nitration agent to prepare gem-dinitro compounds and their scopes of application were summarized， their energetic characteristics were discussed. It is hoped that this review could provide reference for the design and synthesis of new high-energy insensitive energetic materials.

Abstract:Dichloroglyoxime is an efficient industrial bactericide and an important starting material for construction of nitrogen heterocyclic framework， which can be utilized as a pivotal precursor for a variety of high nitrogen energetic materials with excellent performances. Three synthetic methods of dichloroglyoxime， such as chlorine method， NCS/DMF method and NCS/DMF improved method， were introduced， and their advantages and disadvantages were also discussed. Based on the reaction characteristics of dichloroglyoxime， the methods of constructing N-heterocyclic frameworks， such as isoxazole，furoxan， furoxan， bistetrazole and oxadiazolone， were systematically described. Additionally， the physicochemical properties and detonation performances of typical energetic materials were also discussed. Using dichloroglyoxime as starting materials， it is expected to design and synthesize some new energetic materials with excellent performances，and comprehensively promote the innovation ability of energetic materials.

Abstract:

Abstract:The thermal expansion characteristic of explosives under thermal stimulation affects the application of explosives. The thermal expansion characteristic of ［2，2′-bi（1，3，4-oxadiazole）］-5，5′-dinitramide （ICM-101） was studied by using in-situ X-ray powder diffraction， and the thermal expansion coefficient of ICM-101 was obtaind based on Rietveld structure refinement. Results show that there is reversible anisotropic under the high temperature expansion process of ICM-101. In the temperature range of 30-170 ℃， the thermal expansion coefficients of the unit cell parameters a， b， c axis and volume V are 9.19×10^-5 ℃^-1， -9.22×10^-6 ℃^-1， 5.21×10^-5 ℃^-1 and 13.8×10^-5 ℃^-1， respectively. The b-axis exhibits negative expansion characteristics. The unit cell stacking structure of ICM-101 at different temperatures and its correlation with thermal expansion characteristics were studied via the method of molecular spectroscopy technology combined with theoretical calculations. Results show that the compression deformation of the four-membered ring structures of ICM-101 molecules under thermal stimulation is an important reason for the linear negative expansion of the b-axis . Compared with other explosive crystals， the influence of unit cell packing on the thermal stability of explosive crystal structures were analyzed. The thermal expansion anisotropy of explosive crystals with strong hydrogen bonding layered stacked structure is more obvious. When the relative angle between molecules is greater than 100°， the intra-layer hydrogen bonding network affects the interlayer interaction. On the contrary， it will affect the a， b， and c axis directions and limit its thermal expansion.

Abstract:To study the synthetic mechanism and properties of 3，7-dinitro-［1，2，4］triazolo［5，1-c］［1，2，4］triazine-4-amine （TTX），the synthetic mechanism of TTX was studied by density functional theory （DFT）， and the influence of pH value on the cyclization reaction was investigated. Thermal properties and impact sensitivity were studied by differential scanning calorimetry （DSC） and BAM drophammer apparatus， respectively. TTX was synthesized by the coupling reaction of sodium cyanonitromethanide and azo salt of 5-amino-3-nitro-1，2，4-triazole （ANTA）， following by intramolecular cyclization reaction. TTX showed a decomposition temperature of 281.8 ℃ and a apparent activation energy of 356.7 kJ·mol^-1. The impact sensitivity of TTX was measured to be 60 J. Moreover， the compatibility of TTX with HMX， RDX， Al powder and NC was studied. TTX had a good compatibility with Al powder， but a fair compatibility with HMX and a poor compatibility with RDX and NC. Therefore， adding RDX or NC into TTK would apparently increase its sensitity.

Abstract:In order to explore the solid propellant combustion catalyst， a new type of bi-ligand containing energy complex ［Cu（MIM）₂（AIM）₂］（DCA）₂ was synthesized from 1-methylimidazole （MIM）， 1-allyl imidazole （AIM）， copper nitrate and NaDCA， and its structure was characterized by infrared spectroscopy， X-ray single crystal diffraction and powder diffraction. The thermal decomposition process of the energetic complex was analyzed by DSC and TGA. Within the temperature range of 40-500 ℃， there is a melting peak （peak temperature is 93.5 ℃） and an exothermic decomposition peak （peak temperature is 199.4 ℃） in DSC curve. The sensitivity test of the complex shows that the friction sensitivity and impact sensitivity are low and the operation process is safe. Comparing the bi-ligand ［Cu（MIM）₂（AIM）₂］（DCA）₂ with ［Cu（MIM）₄］（DCA）₂ and ［Cu（AIM）₄］（DCA）₂ catalyses on the thermal decomposition of AP， the results show that the bi-ligand complex has better catalytic effect， which advanced the exothermic peak temperature of AP by 88.8 ℃， increased the heat release from 782 J·g^-1 to 2458 J·g^-1， and lowered the thermal decomposition activation energy by 47.1 KJ·mol^-1， implying the potential application as a composite propellant catalyst .

Abstract:Due to conjugated planar molecular structure and additional N-oxide bonds， nitrogen-rich fused-ring N-oxides usually exhibit the advantages of high density， good detonation performances and good sensitivity and they have gradually become a research hotspot of energy materials. This article reviewed molecular structure， synthesis method and physical and chemical properties of twenty nitrogen-rich fused-ring N-oxides that were synthesized in the last decade. At the same time， this article compared some main physical and chemical properties between nitrogen-rich fused-ring N-oxides and their precursors. This review will provide some references for the synthesis and property investigation of new nitrogen-rich fused-ring N-oxides.

Abstract:Fluororubber/glycidyl azide polymer/hexanitrohexaazaisowurtzitane （F₂₆₀₂/GAP/CL-20） composite fibers were prepared through electrospinning process， and the effects of solution concentration， binder ratio， spinning voltage and injection rate on the morphology were explored. Scanning electron microscope （SEM） was used to observe the morphology of composite fibers prepared under different conditions. It is found that when the solution concentration is 20%， the binder F₂₆₀₂/GAP content is 10%， the spinning voltage is 14 kV， and the injection rate is 5×10^-3 L·h^-1， the F₂₆₀₂/GAP/CL-20 composite fiber exhibits a three-dimensional network structure and its surface is uniform and smooth. X-ray diffraction （XRD）， infrared spectroscopy （IR）， differential scanning calorimeter （DSC） and mechanical sensitivity tests were performed on the F₂₆₀₂/GAP/CL-20 composite fiber and raw CL-20. The results show that the crystal form of CL-20 in the composite fiber changes from ε to β after electrospinning. There is no chemical reaction between CL-20 and F₂₆₀₂/GAP during the electrospinning process. After electrospinning， the apparent activation energy of F₂₆₀₂/GAP/CL-20 increases from 178 kJ·mol^-1 of the raw CL-20 to 374.3 kJ·mol^-1， indicating that the composite possesses better thermal stability. The impact sensitivity H₅₀ increases from 21.2 cm to 62.6 cm， and the friction sensitivity decreases from 84% to 52%. Therefore， the effect of sensitivity reduction is significant.

Abstract:It was proved that the sensitivity， safety and density of explosive compound were extremely affected by its morphology and particle size. The influence factor of hexanitrohexaazaisowurtzitane （CL-20） particle size was studied in the recrystallization process with the ultrasonic-assisted recrystallization method， the anti-solvent method and the optimization of agitator type， respectively . The effects of continuous and intermittent ultrasonic with different ultrasonic frequencies （20-40 kHz） were also investigated in order to obtain the small particle size product. In the recrystallization process with anti-solvent method， ethyl acetate and chloroform were applied as solvent and anti-solvent respectively. The dropping acceleration of chloroform （20， 50， 100 mL·h^-1）， the ratio chloroform and ethyl acetate （1∶1， 1∶2， 1∶3）， the recrystallization time （24， 48， 72 h） and temperature （30， 40， 50 ℃） were optimized by orthogonal experiments. In addition， three types of agitator including four straight-blade open turbine， six straight-blade turbine and double-layer dispersing discs were performed in the CL-20 product morphology study together with their stirring speed effect. It was concluded that the assistance of intermittent ultrasonic could considerably reduce CL-20 crystal size. Particle size of 14 μm CL-20 could be obtained by ultrasonic assistant method while the frequency was controlled at 40 kHz with every 30 minutes vibration after 5 minutes stop. Moreover， L9（3⁴）orthogonal experiments were designed and particle size of 140 μm CL-20 could be achieved when the crystallization time， temperature， the chloroform dropping rate， and the dropping amount was 72 h， 30 ℃， 20 mL·h^-1 and 150 mL， respectively. Furthermore， three kinds of agitators were employed in the recrystallization process which obviously effected CL-20 morphology and particle size. A controllable particle size between 40-100 μm CL-20 crystals with spherical shape， a smooth and uniform surface were prepared with the double-layer dispersion disc. Comparing with the four straight blades open turbine type and the six straight blades turbine type agitator， it is proved that the product with desired impact sensitivity and friction sensitivity could be prepared by the double-layer dispersion disc method， which characteristic drop height and the explosion probability were 23.5 cm and 44%， respectively.

Abstract:A new high-energy compound 3，4-bis（（4-chloro-3，5-dinitro-1H-pyrazol-1-yl）methyl）-furoxan was synthesized by using 4-chloropyrazole as raw material， and its single crystal was obtained by solvent evaporation. The structures of this compound and its intermediates were characterized by ¹H and ¹³C NMR， FT-IR， DSC and TG， and the crystal structure of the product was characterized by X-ray single crystal diffraction. Results show that the compound belongs to the orthorhombic space group Pbca， a=10.1817（7） Å， b=16.1917（11） Å， c=21.7300（16） Å， V=3582.4（4） ų， α=90°， β=90°， γ=90°， Z=8， D_c=1.836 g·cm^-1. The Kamlet-Jacobs semi-empirical equation was used to predict the explosion velocity of 8304 m·s^-1 and the explosion pressure of 30.5 GPa. The sensitivities of this compound were measured by the BAM standard method， and the measured impact sensitivity is 9 J and the friction sensitivity is 180 N.

Abstract:As a typical representative of the third generation energetic materials， 2，4，6，8，10，12-hexanitro-2，4，6，8，10，12-hexaazaisowurtzitane （CL-20） is currently the most powerful energetic compound that has already been commercially available. The important research directions are， at present， the optimum synthesis of CL-20 and the preparation of CL-20-based high energy and low sensitivity energetic compounds in the development of energetic materials. The development status of the intermediates in the preparation of CL-20 was analyzed and summarized. The solutions and prospects of the intermediates were also proposed. In addition， the research progress， structural characteristics and main properties of CL-20 crystal products were also discussed. Through sorting out the synthesis and crystals of CL-20， it is concluded that low-cost， high yield， high purity and environmental friendliness are the future development direction of the synthesis process of CL-20.

Abstract:Using nitromethane， tert-butylamine and formaldehyde as raw materials， a novel melt-casting explosive 5-methylnitrate-1，5-dinitrooxazine （TNOP） was synthesized via condensation and nitration reactions with the total yield of 46.2%. FT-IR， ¹H NMR， ¹³C NMR， elemental analysis and single-crystal testing approaches were conducted to obtain the structure of TNOP， disclosing an orthorhombic crystal structure with a space group of Pbca and the density of 1.722 g·cm^-3. The melting point and thermal decomposition temperature were examined to 110.8 ℃ and 203.5 ℃ using DSC technique， respectively. Furthermore， the detonation velocity and the detonation pressure are predicted to be 8112 m·s^-1 and 29.23 GPa based on calculated enthalpy of solid phase formation （-346.6 kJ·mol^-1）. In addition， an impact sensitivity of 50 J could be obtained for TNOP. By coordinating the energetic groups N—NO₂， C—NO₂ and —ONO₂ and facile synthesis process， TNOP was revealed with high energy， low melting point and low sensitivity， implying that it can be used as potential melt-casting explosive in weapons.

Abstract:In order to develop a scale-up and continuous preparation method， the microchannel crystallization technology based on solvent/non-solvent method has been used to prepare hexanitrohexaazaisowurtzitane/octogen （CL-20/HMX） co-crystal. The field emission scanning electron microanalyzer （FE-SEM）， X-ray powder diffraction （XRD）， Raman spectroscopy， Fourier infrared spectroscopy （FT-IR）， thermal analysis and sensitivity test were applied to characterize and analyze the morphology， structure， thermal performance and sensitivity of samples. Results show that this method has successfully prepared CL-20/HMX co-crystal. Its apparent morphology is the flower clusters with a diameter of 20-30 μm， assembled by platelet crystals with thickness of 200-600 nm， accompanying individual flaky crystals （thickness of 200-600 nm）. The CL-20/HMX co-crystal prepared by microchannal crystallization has only one sharp exothermic decomposition peak during the exothermic process. Its exothermic peak temperature is at 243.4 ℃， which is lower than that of the raw materials CL-20 （250.2 ℃） and HMX （284.7 ℃）. Its temperature range of thermal decomposition is only from 242.7 to 246.0 ℃， much narrower than those of raw CL-20 （230.0-254.6 ℃） and HMX （281.0-290.7 ℃）， which means a higher energy release efficiency. Its apparent active energy is 470.75 kJ·mol^-1，falling between CL-20 （175.04 kJ·mol^-1） and HMX （481.45 kJ·mol^-1）， which is 297.29 kJ·mol^-1 hagher than that of raw CL-20，indicating a good thermal stability. Its impact sensitivity is 18 J， which is 8 J and 3.6 J higher than those of raw CL-20 （10 J） and HMX （14.4 J） respectively， and the friction sensitivity is 20% lower than that of raw CL-20. The sensitivity results show the safety of the CL-20/HMX co-crystal has been improved compared with the raw materials.