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To improve the safety of HMX, HMX/NH2-GO composite was prepared with aqueous ammonia functionalized graphene oxide (NH2-GO). The composite was characterized by SEM, Zeta potential, XPS, Raman spectrum, XRD, HPLC, DSC and BAM sensitivity test. The results indicated that the functionalization with aqueous ammonia can enhance the interaction between GO and HMX, and more efficiently desensitize the explosive. The optimal impact sensitivity of the HMX/NH2-GO composite can be not less than 40 J, which is also the most insensitivity compared to the previous reports prepared by coating desensitization with non-energetic desensitized material. Moreover, the potential reason for the different impact and friction sensitivity was also discussed, which may bring a novel perspective to achieve the desensitization of energetic material.

In this work, a fused-ring tetrazolo[4,3-b]pyridazine framework with catenated nitrogen chain was applied to develop new energetic materials with task-specific applications for different purposes. Their syntheses, characterizations and properties were extensively studied. Among them,6-methylnitramimo-7-nitro-8-aminotetrazolo[1,5-b]pyridazine (4) is a potential booster explosive with good detonation velocities (Dv: 8496 m s−1), detonation pressure (P: 28.7 GPa), impact sensitivity (IS: 3 J), friction sensitivity (FS: 112 N) and better decomposition temperature (Td: 200.7 °C) than PETN as well as suitable predicted shock sensitivity (P90% TMD: 1.839 GPa). 6-Nitramimo-7-amino-8-nitrotetrazolo[1,5-b]pyridazine (12) is a high-energy explosive (Dv: 8926 m s−1, P: 33.7 GPa), while bis((7-nitro-8-aminotetrazolo[1,5-b]pyridazin-6-yl)amino)ethane (9) is a heat-resistant explosive (Td: 303.1 °C) with high detonation performances (Dv: 8809 m s−1, P: 29.3 GPa) and low sensitivities (IS: 19 J, FS: 288 N). The analysis of crystal structure, Hirshfeld surface, fingerprint plot, bond dissociation energies (BDEs) and electrostatic potentials (ESP) was used to assess the energy density and sensitivity properties.

Due to it's cost effectiveness and flexibility machining is widely regarded as the backbone of manufacturing. To ensure the aforementioned features of this method, the tooling and process must be configured to suit the material. In literature many publications have analyzed and simulated a two-dimensional (orthogonal) cutting process to this end. This simplification has been proven to be effective and enables predictions for a continuous cut. For the interrupted cut at the heart of our research this approach is not valid and three-dimensional cutting simulations are necessary. Due to the computational complexity involved few publications exist in this area. In this study an Arbitrary-Lagrangian-Eulerian (ALE) scheme is employed using the commercial solver LS-DYNA. To validate the results and determine our model parameters, an inverse method is proposed which uses the digitized surface of manufactured samples. The predicted structure from the simulation was found to be in excellent agreement with the measurements and the model can be used to reduce the need for empirical tests., publishedVersion

The potential practical applications of high-energy 1,3,5,7-tetranittro-1,3,5,7-tetrazocane (HMX) are hindered by their unfavorable safety behavior and sluggish thermal decomposition. This paper proposes dye-assisted assembly of HMX crystals with crystal violet (CV) as soft templates (denoted as CV-HMX). As revealed by the XPS and molecular-dynamics simulations, preferred electrical interactions between HMX and conjugation electrons in planar CV molecular ensure that the resultant CV-HMX has a two-dimensional (2D) microstructure. The BAM impact sensitivity of CV-HMX is 12.5 ​J, higher than that of raw-HMX (5 ​J) and HMX recrystallized from pure water (PW-HMX; 4.5 ​J). Meanwhile, the BAM friction sensitivity of CV-HMX is 320 ​N, also much higher than that of PW-HMX (96 ​N) and raw-HMX (88 ​N). In addition, the decomposition kinetics of CV-HMX is improved due to its large specific surface area and high pore volume. Such dye-template assembly can be applied to a large number of systems, indicating that the method proposed in this work is universal. This work provides synergistic template regulation on morphology and pore structure using general dye-assisted assembly, holding great promises in developing practically viable high energy materials with favorable sensitivity and improved energy release performance.

Six different polymeric matrices were fabricated to reduce the sensitivity of PETN (Pentaerythritol tetranitrate). The polymeric matrices used were individually based on Acrylonitrile butadiene rubber (NBR) softened by plasticizer, styrene-butadiene rubber (SBR) softened by oil, polymethyl methacrylate (PMMA) plasticised by dioctyl adipate (DOA), polydimethylsiloxane (PDMS), polyurethane matrix, and Fluorel binder. A computerised plastograph mixer was utilised for producing three polymer-bonded explosives (PETN-NBR, PETN-SBR, and PETN-PDMS) based on the non-aqueous method. A cast-cured method was used to prepare PBX based on polyurethane (PETN-HTPB), while the slurry technique was used to prepare beads of PETN coated by either fluorel binder (PETN-FL) or based on PMMA forming (PETN-PMMA). The heat of combustion and sensitivities were investigated. The velocity of detonation was measured, while the characteristics of the detonation wave were deduced theoretically by the EXPLO 5 (thermodynamic code). The ballistic mortar experiment was performed to determine the explosive strength. By comparing the results, it was found that PDMS has the highest influence on decreasing the impact sensitivity of PETN, while the cast cured PETN-HTPB has the lowest friction sensitivity. On the other side, PETN-FL has the highest detonation parameters with high impact sensitivity. Several relationships were verified and the matching between the measured results with the calculated ones was confirmed.

Using traditional metallic combustion catalysts in composite solid propellant (CSP) can lead to sharp energy losses of CSP due to the non-energetic properties of the catalysts. In the current study, the energetic ligands based 3D [Cu(atrz)3(NO3)2]n metal-organic frameworks (MOF(Cu)) were first used as the combustion catalysts to study their effects on the performance of CSP. It was found that the variation of MOF(Cu) content in the range of 0–5% had no significant effects on the theoretical specific impulse (Isp) and characteristic velocity (C*) of CSP. MOF(Cu) reduced the high decomposition temperature of AP to 344 °C and the complete decomposition temperature of CSP to 358 °C. It also decreased the thermal decomposition activation energy of CSP from 74.1 kJ mol−1 to 63.3 kJ mol−1. The CSP containing MOF(Cu) exhibits higher burning rates, particular flame structure and lower pressure index, as compared with that with CuO as the catalyst. The mechanical sensitivity test results reveal that MOF(Cu) can reduce the friction sensitivity and impact sensitivity of CSP from 40% and 39.4 cm to 32% and 63.5 cm, respectively. The current study is promising to develop a new kind of energetic combustion catalysts for CSP.

Six energetic compounds bearing the dinitromethyl group and based on the triazolotriazine fused ring skeleton were achieved. All structures were confirmed using infrared spectroscopy (IR), 1H NMR and 13C NMR spectroscopy, high-resolution mass spectrometry (HRMS) and differential scanning calorimetry (DSC). Among them, potassium salt and neutral compound 3,7-bis(fluorodinitromethyl)-[1,2,4]triazolo[5,1-c][1,2,4]triazin-4-amine exhibit high densities (2.06 g cm−3 and 1.95 g cm−3, respectively), detonation velocities of up to 9028 m s−1, and excellent friction sensitivity (>360 N).

At present, the preparation of propellants with high safety and good thermal decomposition performance is still a challenge. An ammonium perchlorate/cobalt acetate hydroxide (AP/Co3(CH3COO)5(OH)) composite was synthesized in situ via liquid deposition. Owing to the barrier effect and heat absorption of cobalt acetate hydroxide, the resulting composite offers reductions in the impact sensitivity and friction sensitivity by 10.2 cm and 96%, respectively. Moreover, with the increase in temperature, cobalt acetate hydroxide coated on the AP surface in situ decomposed into monodisperse CoO nanoparticles around 223 °C, which reduced the high temperature decomposition of ammonium perchlorate from 426.8 °C to 332.8 °C. The real-time FT-IR spectra showed that CoO mainly accelerates the oxidation of ammonia and the conversion of N2O to NO by promoting electron transfer, thereby catalyzing the thermal decomposition of AP. These confirmed that preparing the AP/Co3(CH3COO)5(OH) composite will lay a foundation for the development of novel high safety performance and high burning rate AP-based solid propellants, showing a broad application prospect.

The traditional large-dosage and dangerous methods for the determination of the sensitivities of energetic materials (EMs) have always led to low-accuracy diagnoses with poor repeatability, since they are affected by crystalline quality, experimental conditions, etc. Herein, a simple method is developed to determine various sensitivities, such as impact sensitivity, friction sensitivity, electrostatic sensitivity, and laser sensitivity, via laser spark spectrometry (LSS), with the consumption of only several milligrams of EM, rather than macro-detonation testing. Based on suitable correlated prediction models using the entire LSS spectrum and physical-parameter-corrected statistical regression, the friction sensitivity, electrostatic sensitivity, and laser sensitivity can be well predicted, evaluating the impact of various factors on sensitivity. The correlations between plasma temperature and impact sensitivity, electron density and friction sensitivity, and oxygen balance and electrostatic sensitivity are also clarified. This can facilitate sensitivity predictions with high precision. This method provides a safe, low-dosage, high-precision, and low-cost approach for sensitivity estimations of EMs.

In order to improve the energy performance and mechanical properties of insensitive high-energy propellants, cyclotrimethylenetrinitramine (RDX)-based insensitive high-energy propellant with nitrocellulose (NC) and glycidyl azide polymer-energetic thermoplastic elastomer (GAP-ETPE) blends as the binder was prepared by solvent method. The effects of GAP-ETPE/NC ratio and RDX content on the energy properties of propellants were analyzed by numerical calculations. The effects of GAP-ETPE/NC ratio, RDX particle size and RDX content on the mechanical properties of propellants were studied by compression test, impact test and solid surface properties test. The impact sensitivity and friction sensitivity of all the propellant compositions were tested. The theoretical calculation results showed that the introduction of GAP-ETPE into propellant significantly decreased the explosion temperature and increased the specific volume. The density, compression strength, and surface energy of the propellant were gradually decreased with increasing the GAP-ETPE/NC ratio, and the impact strength was increased gradually as well. The mechanical properties and surface energy of the propellant were improved greatly when the RDX particles were smaller. The studied propellants showed a linear increase in the propellant force and explosion temperature with increasing the RDX content. However, increasing the RDX content significantly reduced the impact strength and surface energy. Mechanical reinforcement with solid fillers increased the compression strength and propellant density to a certain degree. Compared with the standard propellants SF-3, the prepared propellant composition is insensitive to the impact and friction.

The creation of high-performance energetic materials with good mechanical sensitivities has been a great challenge over the past decades, since such materials have huge amounts of energy and are thus essentially unstable. Here, we report on a promising fused-ring energetic material with an unusual two-dimensional (2D) structure, 4-nitro-7-azido-pyrazol-[3,4-d]-1,2,3-triazine-2-oxide (NAPTO), whose unique 2D structure has been confirmed by single-crystal X-ray diffraction. Experimental studies show that this novel energetic compound has remarkably high energy (detonation velocity D = 9.12 km·s−1; detonation pressure P = 35.1 GPa), excellent sensitivities toward external stimuli (impact sensitivity IS = 18 J; friction sensitivity FS = 325 N; electrostatic discharge sensitivity EDS = 0.32 J) and a high thermal decomposition temperature (203.2 °C), thus possessing the dual advantages of high energy and low mechanical sensitivities. To our knowledge, NAPTO is the first fused-ring energetic material with 2D layered crystal stacking. The stabilization mechanism toward external stimuli were investigated using molecular simulations, and the theoretical calculation results demonstrate that the ultraflat 2D layered structure can buffer external mechanical stimuli more effectively than other structures by converting the mechanical energy acting on the material into layer sliding and compression. Our study reveals the great promise of the fused-ring 2D layered structure for creating advanced energetic materials.

A recent near miss involving ignition of a small amount of red phosphorus was investigated. The near miss is discussed in detail along with the root cause investigation. Six possible root causes we...

In this work, considering the various practical concerns during storage, processing, handling and emission of flash powder used for making firecracker, a slight modification was made in chemical composition of flash powder to overcome all the above-mentioned practical concerns. Generally, flash powder chemical composition consists of KNO3-60%, Al-20% and S-20% for making firecrackers. The modification was made by replacing 5% and 10% of sulfur with tamarind seed powder (TSP) in the flash powder composition. In this study, all the chemicals used for making flash powder were of nanometer size. Using this TSP-based flash powder, the bijili crackers were fabricated and tested for noise level. The performance of the noise level by TSP-based flash powder was within the specified limits. The safety aspect of TSP-based flash powder was tested for its impact and friction sensitivity. To understand the thermal behavior of the TSP-based flash powder, TG analysis and DSC were performed and compared with existing flash powder composition. The results showed that TSP could be a perfect substituent for sulfur and could play a vital role in the making of eco-friendly (Green) crackers.

Friction sensitivity of composite propellants and their ingredients is of significant interest to mitigate the risk associated with the accidental initiation while processing, handling, and transportation. In this work, attempts were made to examine the friction sensitivity of passive binder: Hydroxy Terminated Polybutadiene/Aluminium/Ammonium Perchlorate and active binder: (Polymer + Nitrate Esters)/Ammonium Perchlorate/Aluminium/Nitramine based composite propellants by using BAM Friction Apparatus. As per the recommendation of NATO standard STANAG–4487, the friction sensitivity was assessed by two methods: Limiting Frictional load and Frictional load for 50% probability of initiation (F50). The test results showed that the active binder based formulations were more vulnerable to frictional load as compared to the formulations with passive binders. Examination of a comprehensive set of propellant compositions revealed that the particle size distribution of Ammonium Perchlorate and burn rate catalysts were the most influential factors in dictating the friction sensitivity for HTPB/Al/AP composite propellants. For active binder/AP/Al/Nitramine composite propellants, the formulation with RDX was found more friction sensitive with a sensitivity value of 44 N as compared to its HMX analog (61 N). The correlation studies of friction sensitivity, burning rate, and thermal decomposition characteristics of HTPB/Al/AP composite propellants is described.

Understanding the factors that affect explosive sensitivity is paramount to the safe handling and development of new explosives molecules. Erythritol tetranitrate (ETN) is an explosive that recently has attracted significant attention in the explosives community because of its ease of synthesis and physical properties. Herein, we report the synthesis of ETN derivatives using azide, nitramine, and nitrate ester functional groups. Impact, spark, and friction sensitivity measurements, computationally calculated explosive properties, and the crystal structure analysis of the ETN derivatives are reported. Mixing explosive functional groups led to changes in the explosive sensitivity, explosive performance as well as physical properties including melting point and physical state at room temperature. Overall, we have demonstrated that combining functional groups can enable the tuning of explosive and physical properties of a molecule. This tunability can potentially aid in the development of new explosives in which characteristics are varied to meet certain specifications.

One of the most challenging tasks in the field of light‐producing pyrotechnics is the generation of saturated blue light with high spectral purity. Only copper salts in combination with chlorine seem to be high‐performing blue light emitters. However, in modern pyrotechnics the application of chlorine should be avoided. Different strategies are presented to further fine‐tune literature‐known chlorine‐free blue‐light‐emitting pyrotechnical compositions. The copper iodate as well as the copper bromate systems have been studied by using small amounts of nitrogen‐rich compounds like 1,2,4‐triazole, 5‐amino‐1H‐tetrazole or 3‐nitro‐1H‐1,2,4‐triazole. To overcome sensitivity issues, a two‐component epoxy binder system was introduced. The application of both copper(I) iodide and copper(I) bromide in the same pyrotechnical formulation were considered as blue‐light‐emitting species. Further, a quite new approach by using copper(I) nitrogen‐rich coordination compounds was investigated to give a blue flame color. All relevant formulations were characterized with respect to their dominant wavelength and spectral purity as well as impact and friction sensitivity.

High endothermicity is one of the most important factors in the design of high-performance energetic materials for a new generation of rocket technologies. Taking this into account, in this study, novel highly energetic cage compounds were synthesized by the incorporation of a high-enthalpy N-azidomethyl moiety into the polynitro hexaazaisowurtzitane backbone. All obtained compounds were fully characterized by high-resolution mass spectrometry, IR and multinuclear NMR (1H, 13C, 14N, 15N) spectroscopy. For two of them, 4-azidomethyl-2,6,8,10,12-pentanitrohexaazaisowurtzitane and 4,10-bis(azidomethyl)-2,6,8,12-tetranitrohexaazaisowurtzitane, the density and structural features were established by X-ray diffractometry. Enthalpies of formation were determined experimentally by combustion calorimetry. Thermal stability measurements and testing of impact and friction sensitivity were also carried out. The synthesized compounds exhibit a high level of heat resistance (decomposition onset 180–205 °C) and density (1.85–1.93 g cm−3). Their enthalpies of formation on a unit of mass (up to 2210 kJ kg−1) are the highest among the known hexaazaisowurtzitane derivatives and are 2–2.5 times that of CL-20. The combination of these attractive properties makes the new materials promising energetic components for propellant compositions.

Extensive density functional theory (DFT) calculation and data analysis on molecular and crystal level features of 60 reported energetic materials (EMs) allowed us to define key descriptors that are characteristics of these compounds’ thermostability. We see these descriptors as reminiscent of “Lipinski’s rule of 5”, which revolutionized the design of new orally active pharmaceutical molecules. The proposed descriptors for thermostable EMs are of a type of molecular design, location and type of the weakest bond in the energetic molecule, as well as specific ranges of oxygen balance, crystal packing coefficient, Hirshfeld surface hydrogen bonding, and crystal lattice energy. On this basis, we designed three new thermostable EMs containing bridged, 3,5-dinitropyrazole moieties, HL3, HL7, and HL9, which were synthesized, characterized, and evaluated in small-scale field detonation experiments. The best overall performing compound HL7 exhibited an onset decomposition temperature of 341 °C and has a density of 1.865 g cm–3, and the calculated velocity of detonation and maximum detonation pressure were 8517 m s–1 and 30.6 GPa, respectively. Considering HL7’s impressive safety parameters [impact sensitivity (IS) = 22 J; friction sensitivity (FS) = 352; and electrostatic discharge sensitivity (ESD) = 1.05 J] and the results of small-scale field detonation experiments, the proposed guidelines should further promote the rational design of novel thermostable EMs, suitable for deep well drilling, space exploration, and other high-value defense and civil applications., A comprehensive computational analysis of energetic materials allowed the drawing of thermostability guidelines, inspiring the design of new thermostable explosives, which were synthesized and evaluated.

A series of novel energetic materials comprising of azo-bridged furoxanylazoles enriched with energetic functionalities was designed and synthesized. These high-energy materials were thoroughly characterized by IR and multinuclear NMR (1 H, 13 C, 14 N) spectroscopy, high-resolution mass spectrometry, elemental analysis, and differential scanning calorimetry (DSC). The molecular structures of representative amino and azo oxadiazole assemblies were additionally confirmed by single-crystal X-ray diffraction and X-ray powder diffraction. A comparison of contributions of explosophoric moieties into the density of energetic materials revealed that furoxan and 1,2,4-oxadiazole rings are the densest motifs while the substitution of the azide and amino fragments on the nitro and azo ones leads to an increase of the density. Azo bridged energetic materials have high nitrogen-oxygen contents (68.8-76.9 %) and high thermal stability. The synthesized compounds exhibit good experimental densities (1.62-1.88 g cm-3 ), very high enthalpies of formation (846-1720 kJ mol-1 ), and, as a result, excellent detonation performance (detonation velocities 7.66-9.09 km s-1 and detonation pressures 25.0-37.7 GPa). From the application perspective, the detonation parameters of azo oxadiazole assemblies exceed those of the benchmark explosive RDX, while a combination of high detonation performance and acceptable friction sensitivity of azo(1,2,4-triazolylfuroxan) make it a promising potential alternative to PETN.

In this study, a novel spray drying-assisted self-assembly (SDAS) technology was proposed to prepare submicron elemental explosives with good morphology, uniform dispersion, and low sensitivity and spherical submicron RDX, HMX, and CL-20 particles without soft agglomeration were fabricated via such a method. Structural characterizations and thermal stability of the composites were systematically studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). Moreover, safety performance was analyzed by qualitative testing of impact sensitivity and friction sensitivity. The XRD analysis demonstrated that HMX and CL-20 refined by SDAS maintained the crystal structure of β-HMX and ε-CL-20 before and after refinement, whereas the HMX crystal structure after spray recrystallization refinement was transformed from β-HMX to α-HMX. The DSC results indicated that the thermal decomposition peak temperature of the three particles refined by the SDAS technology had a minimum advancement, and the thermal stability of the particles was relatively superior. More importantly, the H50 of the RDX, HMX, and CL-20 refined by this novel method was increased to 48.3 cm, 44.6 cm, and 31.1 cm, and the probability of friction explosion was decreased to 62%, 62%, and 80%, respectively, thus significantly improving the safety performance as compared with the sample refined by spray recrystallization.

A series of fused-ring energetic materials, i.e., 3,6-dinitro-1,4-di(1H-tetrazol-5-yl)-pyrazolo[4,3-c]pyrazole (DNTPP, compound 2) and its ionic derivatives (compounds 3-8), were designed and synthesized in this study. The molecular structures of compounds 2, 3, 6, 7·2H2O, and 8 were confirmed using single-crystal X-ray diffraction. Their physicochemical and energetic properties, such as density, thermal stability, heat of formation, sensitivity, and detonation properties (e.g., detonation velocity and detonation pressure), were also evaluated. The results indicate that DNTPP and most of its ionic derivatives are extremely thermally stable and insensitive toward mechanical stimuli. In particular, the thermal decomposition temperature of compound 3 is up to 329 °C, while compounds 7 and 8 are very insensitive (impact sensitivity: >20 J; friction sensitivity: >360 N). Compounds 2, 3, and 6 possess good comprehensive properties, including excellent thermal stability, remarkable low sensitivities, and favorable detonation performance. These features show that DNTPP and its ionic derivatives have considerable promise as thermally stable and insensitive energetic materials.

A solvothermal reaction of Co(CH3COO)2·4H2O and 5-mercapto-1-methyl-tetrazole (Hmmtz) in methanol (MeOH) yielded a one-dimensional solvent-free energetic coordination polymer, namely, [Co(mmtz)2] n1, which was structurally characterized. The enthalpy of formation (ΔfH°) of 1 (907 kJ mol-1) is much larger than that of commercial 2,4,6-trinitrotoluene (-59 kJ mol-1). The impact sensitivity and the friction sensitivity are greater than 40 J and 360 N, respectively, indicating that compound 1 exhibits a potential application as a safe explosive. Temperature-dependent molar magnetic susceptibilities show that weak antiferromagnetic behavior exists in 1.

Cellulose nitrates corresponding in the basic properties to high-viscosity lacquer-grade colloxylin were prepared by esterification of cellulose pulp, isolated from domestic rapidly renewable feedstock—agroindustrial waste—oat hulls, or cotton cellulose with a sulfuric and nitric acid mixture. The experimental samples of cellulose nitrates were comparatively evaluated. The IR and 13С NMR spectroscopy data confirmed the identity of chemical structure. High chemical purity of samples was confirmed by differential scanning calorimetry and ampule chromatography procedure. The cellulose nitrate samples have satisfactory mechanical sensitivity level: the lower limit of impact sensitivity is 50 mm and that of friction sensitivity is 1200 kgf/cm2; they have good chemical compatibility and high chemical stability when blended with plasticizers. The obtained results attest to expediency of using cellulose nitrates from oat hulls as a component of explosive compositions.

To improve the thermal decomposition property of cyclotrimethylenetrinitramine (RDX), a new nano-energetic combustion catalyst nitrated graphene oxide (NGO), which was synthesized by nitrifying graphene oxide with nitro-sulfuric acid, is introduced to RDX via a solvent–antisolvent method. A scanning electron microscope was used to investigate the morphology of RDX, NGO and the 2% NGO/RDX nano-energetic composite. The properties and the mechanisms of thermal decomposition of the NGO/RDX nano-energetic composites in different blend ratios were analyzed through thermogravimetry–differential scanning calorimetry and thermogravimetry–mass spectra, respectively. In comparison with RDX, the thermal decomposition temperature of 2%NGO/RDX decreased from 246 to 224 °C, and the apparent decomposition heat enhanced from 761 to 1651 J g−1. The tests of impact sensitivity and friction sensitivity were carried out by a standard method. The value of h50 of 2%NGO/RDX increased from 24 to 40 cm and the friction sensitivity of 2%NGO/RDX reduced from 86 to 12% compared with RDX. These results indicated that NGO had an excellent catalytic property upon the thermal decomposition of RDX and it can also improve its impact sensitivity and friction sensitivity.

Dicarbohydrazide bis[3-(5-nitroimino-1,2,4-triazole)] (DCBNT) was firstly synthesized by ion exchange and salt formation reaction. A combination of single-crystal X-ray diffraction (SXRD), FTIR, 1H NMR, 13C NMR, and elemental analysis was utilized to analyze the structure and composition of DCBNT. DCBNT exhibits a high detonation velocity of 9234.87 m s−1 and a detonation pressure of 31.73 GPa as calculated by EXPLO5 v6.02 program. In addition, the sensitivities (impact sensitivity >40 J, H50 = 90 cm, and friction sensitivity = 216 N) and thermal stability (>230 °C) of DCBNT were investigated. Moreover, we measured the solubility of DCBNT in 12 common solvents by a polythermal method system which demonstrates its poor solubility in common organic solvents and water. These excellent physicochemical properties make DCBNT an environmentally friendly, low-sensitivity and high-energy explosive.

Crystal engineering has prompted the development of energetic materials in recent years. Obtaining an explosive crystal with an ideal crystal shape and a single polymorph with high packing density and stability needs to be further studied. This work reports the synthesis, structure and energetic properties of picrylhydrazone and indazole derivatives. We presented a cyclization reaction in which the twist structure picrylhydrazones (4 and 6) with a disordered crystal packing style was converted into planar structure indazole derivatives (5 and 7) with a face-to-face crystal packing style. Compared to picrylhydrazones 4 and 6, the indazole derivatives 5 and 7 exhibited increases of 0.04 and 0.05 g cm−3 (2.4%, 2.8%), 0.07 and 0.39 kJ g−1 (3.3%, 19.3%), 341 and 309 m s−1 (4.3%, 3.7%), 2.5 and 2.9 GPa (10.9%, 11.7%), 82 and 127 K (17.9%, 27.5%), 9 and 7 J (37.5%, 31.6%) and 64 and 29 N (25.4%, 11.0%) in density, heat of formation (ΔfH), detonation velocity (D) and pressure (P), decomposition temperature (Tdec), impact sensitivity (IS) and friction sensitivity (FS), respectively. According to the experimental results and theoretical calculations, the structure–property relationship was demonstrated. Among target compounds, indazole derivative 7 exhibits an acceptable detonation performance and good sensitivity (Tdec = 316 °C, IS = 27 J, D = 8518 m s−1). This study enriches future prospects for the molecular design and crystal engineering of energetic materials.

5-(4-Azidofurazan-3-yl)-1-hydroxytetrazole (4) and its ammonium (4a), hydroxylammonium (4b), and hydrazinium (4c) salts were synthesized. Each compound was characterized by X-ray single crystal structure diffraction, infrared (IR), and 1H and 13C NMR spectroscopy, elemental analyses, thermal stability, and sensitivity to external stimulants. Crystal structures and packing coefficients were analyzed and compared with respect to π–π stacking and hydrogen bonding. Due to the presence of lattice water in compound 4, the impact sensitivity (IS = 15 J) and friction sensitivity (FS = 120 N) are notably lower than those of the anhydrous material (IS = 3 J, FS = 20 N), which could act as a primary explosive. In this way, the primary explosive could be synthesized, transported, and stored more safely than traditional primary explosives. The detonation properties determined by EXPLO 6.02 software show that among the four compounds, 4b has superior detonation velocity (Vd = 9201 m s−1) and pressure (P = 36.0 GPa) values which are comparable to those of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine). The impact sensitivity (10 J) is less-sensitive than HMX (7.5 J), which suggests compound 4b as a potential alternative to HMX.

Five novel nitrogen-rich energetic materials were synthesized using 3,6-bis(3,5-dimethyl-pyrazole-1-yl)-1,2,4,5-tetrazine (BT) and 3,6-bis(pyrazole-1-yl)-1,2,4,5-tetrazine as raw materials. The materials were comprehensively characterized by single-crystal X-ray diffraction, FT-IR, mass spectra and elemental analysis. The synthesized compounds show good experimental densities, ranging from 1.59 to 1.70 g cm−3. DSC technology was used for analyzing the thermal stability. The decomposition temperatures of the five energetic materials ranged from 204.0 to 276.5 °C. Non-isothermal kinetic parameters and formation enthalpy values were computed. In addition, friction sensitivity measurements were performed according to BAM methods, and the results showed that the five compounds can be classified as insensitive energetic materials. For a better understanding of the electronic structural characteristics, the electrostatic potential (ESP) and natural bond orbitals (NBOs) of compounds 1 and 2 were further computed. The detonation parameters were obtained via EXPLO5 V6.04. The detonation velocities of the five energetic materials were found to be in the range of 6436 m s−1 to 7759 m s−1, and their detonation pressures are between 15.8 GPa and 24.6 GPa. Most of them exhibit much better detonation performance than TNT.