High-nitrogen Energetic Materials Research Articles

Efficient Synthesis, Characterization, and DFT Calculation of 4,4’-Azo-1,2,4-triazole

ABSTRACT 4,4’-Azo-1,2,4-triazole (atrz) is a new high nitrogen energetic material with high energy density, high gas yield and wide application prospects, but the low synthesis temperature and long time are the main reasons limiting its application. To achieve efficient synthesis of atrz, the double drop synthesis method was designed to solve the problem of unstable concentration of oxidant (HClO) due to batch feeding. The reaction temperature, reaction time, and molar ratio of reactants of n(4-amino-1,2,4-triazole):n(ClO−) were studied and optimized using the single factor variable method; Characterization and analysis of atrz using theoretical calculations with elemental analysis, infrared spectroscopy, crystal morphology, and nuclear magnetic resonance; The thermal properties and stability of atrz were tested and analyzed using TG-DTA. The results showed that the reaction time of the double drop synthesis method was shortened from 5 hours to 1.5 hours under the conditions of similar yield, and the efficiency was increased by 2.3 times. The optimized process was a reaction temperature of 5°C-10°C, reaction time of 1.5 hours, n(4-amino-1,2,4-triazole):n(ClO−) of 1:2, and the yield reached 73%. The product was white, needle-like crystals, which were determined to be atrz by means of characterization and theoretical calculations. Atrz’s decomposition peak temperature is 309.0°C, and when the temperature is below 271.7°C, atrz is thermally stable. The activation energies of atrz calculated by Kissinger and Flynn-Wall-Ozawa methods were 195.0 kJ·mol−1 and 194.6 kJ·mol−1.

Synthesis and characterization of 2-amino-4,5-bis(tetrazol-5-yl)-1,2,3-triazole: A high-nitrogen energetic material with low sensitivities and high thermal stability

In this study, a high-nitrogen insensitive energetic material, 2-amino-4,5-bis(tetrazole-5-yl)-1,2,3-triazole (H2ABTT), was successfully synthesized by introducing the N-amino group on the 1,2,3-triazole ring. This compound exhibits excellent properties in many aspects. Compared to 4,5-bis(tetrazol-5-yl)-1,2,3-triazole (H3BTT), which has a decomposition temperature (Td) of 277 °C, nitrogen content of 75.11 %, density of 1.69 g cm−3, a detonation velocity of 8630 m s−1, a detonation velocity of 26.3 GPa, an impact sensitivity (IS) of 2 J, and a friction sensitivity (FS) of 240 N, H2ABTT exhibits higher thermal stability of Td:303 °C, higher nitrogen content of N%:76.35 %, higher density of 1.86 g cm−3, more desirable detonation properties (detonation velocity Dv: 9185 m s−1; detonation pressure p: 31.7 GPa), and lower mechanical sensitivities (IS > 100 J; FS > 360 N). Furthermore, H2ABTT outperforms insensitive explosive TATB (Dv = 8179 m s−1; p = 30.5 GPa; IS = 50 J; FS > 360 N) in some properties, making it a potential high-performance insensitive explosive. Besides, energetic salts 4–6 were successfully synthesized based on H2ABTT. The calculated results show that some of these salts even possess higher detonation performance compared to H2ABTT.

Recent Progress on Nitrogen-Rich Energetic Materials Based on Tetrazole Skeleton.

Development of nitrogen-rich energetic materials has gained much attention because of their remarkable properties including large nitrogen content and energy density, good thermal stability, low sensitivity, good energetic performance, environmental friendliness and so on. Tetrazole has the highest nitrogen and highest energy contents among the stable azoles. The incorporation of diverse explosophoric groups or substituents into the tetrazole skeleton is beneficial to obtain high-nitrogen energetic materials having excellent energetic performance and suitable sensitivity. In this review, the development of high-nitrogen energetic materials based on tetrazole skeleton is highlighted. Initially, the property and utilization of nitrogen-rich energetic materials are presented. After showing the advantage of the tetrazole skeleton, the high-nitrogen energetic materials based on tetrazole are classified and introduced in detail. Based on different types of energetic materials (EMs), the synthesis and properties of nitrogen-rich energetic materials based on mono-, di-, tri- and tetra-tetrazole are summarized in detail.

Unrevealing the phase transition of high-performing high-nitrogen energetic material 1,5-diaminotetrazole-4: N-oxide via first-principles studies

The effect of pressure on crystal structures, electronic properties, hydrogen bonds, optical properties and mechanical features of high-performing energetic material 1,5-diaminotetrazole-4: N-oxide was investigated by high-precision DFT-D method. The results reveal that there exists a critical point of phase transition around 8 GPa, reflected in various properties of the crystal. Band gap decreases gradually as the pressure increases, illustrating electrons are easier to transit from occupied orbit to the empty. The DOS analysis indicates that C-NH2, N-NH2 and N = O bonds may play a role as a reaction channel for the initial decomposition under high pressures. The hydrogen bond analysis indicates that pressure can alter the distribution of hydrogen bond in the crystal and modify the physicochemical properties. The absorption spectra of the crystal under high-pressure conditions show several strong bands in UV–visible region. The analysis on mechanical properties reveals that pressure can effectively improve the rigidity, plasticity and ductility for the crystal. Our results clarify the effect of pressure on energetic materials and are conducive to find the new crystalline phases for energetic materials.

Comparative study on 1,2,3-triazole based azo- and triazene-bridged high-nitrogen energetic materials

Two different 1,2,3-triazole based energetic compounds, featuring with azo (-NN-) and triazene (-NN–NH-) bridge were investigated. All newly synthesized compounds were fully characterized by multinuclear NMR spectroscopy, infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Comparative study indicated that both of them are insensitive to the external mechanic stimuli, however, the other key energetic properties of azo compound (E)-1,2-bis(2-methyl-5-nitro-2H-1,2,3-triazol-4-yl)diazene(2), e.g., density, detonation velocity and pressure are superior to those of triazene compound (E)-5,5'-(triaz-1-ene-1,3-diyl)bis(2-methyl-4-nitro-2H-1,2,3-triazole) (1). This work gives a revelation on the two different types nitrogen-bridged energetic materials, especially in rarely triazene-bridge type explosives.

The influence of energy content and its outputs on the impact sensitivity of high-nitrogen energetic materials

ABSTRACT On 15 high nitrogen and three polynitrated polyazaarenes (including six azido-derivatives), the paper demonstrates the relations between their impact sensitivities (Edr ) on the one hand and the volume heats (ρQmax ) or a representative of detonation pressure (ρD2 ) of their explosion or their enthalpies of formation (ΔHform ) on the other. The semi-logarithmic subrelations between the Edr and ρQmax values are limited by the mechanism of primary fission. While the mentioned relations between Edr and ρQmax values for azido derivatives predominantly show the expected course, in the case of the remaining high-nitrogen EMs, the opposite is the case, i.e., an increase in ρQmax values corresponds to a decrease in impact sensitivity. The same is valid for ρD2 values as an independent variable. Taking the energy content of the studied EM molecules, represented by ΔHform values, instead of the heat of explosion, yields unambiguous semilogarithmic relations, according to which the growth of the ΔHform values increases impact sensitivity. The results obtained indicate that it is necessary to distinguish between the influences of the performance and the energetic content of high-nitrogen energetic materials on their initiation reactivity.

The influence of energy content and its expenditure on the impact sensitivity of high-nitrogen energetic materials

On 17 high-nitrogen energetic materials (including six azido-derivatives), the paper demonstrates the relations between their impact sensitivities (Edr ) on the one hand and the volume heats (ρQmax ) or a representative of detonation pressure (ρD2 ) of their explosion or their enthalpies of formation (ΔHform ) on the other. The semi-logarithmic subrelations between the Edr and ρQmax values are limited by the mechanism of primary fission. While the mentioned relations between Edr and ρQmax values for azido derivatives predominantly show the expected course, in the case of the remaining high-nitrogen EMs, the opposite is the case, i.e. an increase in ρQmax values corresponds to a decrease in impact sensitivity. The same is valid for ρD2 values as an independent variable. Taking the energy content of the studied EM molecules, represented by ΔHform values, instead of the heat of explosion, yields unambiguous semilogarithmic relations, according to which the growth of the ΔHform values increases impact sensitivity. The results obtained indicate that it is necessary to distinguish between the influences of the performance and the energetic content of high-nitrogen energetic materials on their initiation reactivity.

The Influence of Energy Content and Its Expenditure on the Impact Sensitivity of High-Nitrogen Energetic Materials

Based on the analysis of a large amount of experimental data, Licht has stated [1] that a high level of performance is usually accompanied by an enhanced sensitivity and that insensitive explosives do not exhibit top performance. This statement might be taken as a rule [1,2,3]. Nevertheless, there are some exceptions to it [2,3] (the opposite run of the corresponding relationship), mainly in pure, technically attractive nitramines [3] and in some highly thermostable polynitroarenes [4]. Only recently, the energy gain from the explosion of energetic materials (i.e. the heat of explosion) in that type of studies has been replaced by their energy content, i.e. by their enthalpy of formation, ΔHform [5]. So far, we have dealt with compounds with nitro groups in the molecule. However, the research in the last two decades has focused on energetic materials, mainly with a high nitrogen content, which is bound in their molecules mostly in another form than the nitro groups.

고질소 에너지 물질 Hydrazinium 5-aminotetrazolate (HAT)의 제조

고질소 에너지 물질 Hydrazinium 5-aminotetrazolate (HAT)의 제조

Azo-linked high-nitrogen energetic materials

In this review, we document the most recent developments in azo-linked heteroaromatic (imidazole, pyrazole, triazole, triazine, tetrazine and oxadiazole) high-nitrogen energetic materials and their salts.

Cocrystal Engineering of a High Nitrogen Energetic Material

Cocrystallization of energetic materials has emerged as a strategy to modulate properties through directed selection of coformers. Here, the cocrystallization of a high-nitrogen energetic material, 3,6-bis(1H-1,2,3,4-tetrazol-5-ylamino)-s-tetrazine (BTATz), is detailed. The utility of electrostatic potential maps to predict the behavior of coformers with BTATz is demonstrated as well as a critical requirement for regions of sufficiently negative electrostatic potential on the coformer (Vs,min). Cocrystal structures are compared to the solvent-free structure of BTATz, determined here for the first time. The new materials exhibit good thermal stability (>200 °C) and are insensitive to impact. Cocrystallization of BTATz demonstrates the capability of high-nitrogen energetic materials to form multicomponent crystal systems and reaffirms the ability of coformers to modulate energetic performance.

1‐(2H‐Tetrazolyl)‐1,2,4‐triazole‐5‐amine(TzTA) – A Thermally Stable Nitrogen Rich Energetic Material: Synthesis, Characterization and Thermo‐Chemical Analysis

AbstractThe targeted high nitrogen energetic material 1‐(2H‐tetrazol‐5‐yl)‐1,2,4‐triazol‐5‐amine (TzTA) was synthesized from 3‐amino‐1,2,4‐triazole via a two‐step procedure using cyanogen bromide and sodium azide. TzTA was prepared in good yields and characterized using analytical (elemental) and spectroscopic (IR, Raman, NMR) techniques. The crystal structure of sulfate salt of the molecule was solved by means of low temperature X‐ray crystallography, which showed the co‐planarity of the two rings. The sulfate salt of the molecule crystallized in monoclinic system P21/n, with a crystal density of 1.856 g cm−3. The thermal stability of the molecule was assessed by DSC. The molecule showed excellent thermal stability better than many known nitrogen rich energetic molecules and showed comparable thermal stability with HMX. Non‐isothermal kinetics was performed on the molecule to derive the activation energy. Constant volume combustion energy was determined using oxygen bomb calorimeter and back calculated the heat of formation. Preliminary insight on the gas generating capability of the molecule was tested by measuring the dynamic pressure generated inside a closed bomb. Dynamic pressure of an oxygen balanced system (TzTA and ADN) was also measured using the Parr dynamic pressure measurement system.

Nitrogen-doped carbon based on peptides of hair as electrode materials for surpercapacitors

Abstract Hair, a high-nitrogen energetic material, is utilized as a precursor for nitrogen-doped porous carbon. The preparation procedures for obtaining carbon from hair are very simple, namely, reductant or deionized water activation process followed by hair carbonization under argon atmosphere at 800 °C for 2 h. The samples are characterized through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption, and X-ray photoelectron microscopy. The carbon samples are tested as electrode materials in supercapacitors in a three-electrode system. The carbon (soaked in deionized water at 80 °C) presents relatively low specific surface areas (441.34 m 2 g −1 ) and shows higher capacitance (154.5 F g −1 ) compared with nitrogen-free commercial activated carbons (134.5 F g −1 ) at 5 A g −1 . The capacitance remains at 130.5 F g −1 even when the current load is increased to 15 A g −1 . The capacitance loss is only 5% in 6 M KOH after 10,000 charge and discharge cycles at 5 A g −1 . It is the unique microstructure after activation processing and electroactive nitrogen functionalities that enable the carbon obtained through a simple, ecological, and economical process to be utilized as a potential electrode material for electrical double-layer capacitors.

Preparation, Structural Investigation and Thermal Decomposition Behavior of Two High-Nitrogen Energetic Materials: ZTO·2H2O and ZTO(phen)·H2O

O, there is intermolecular hydrogen bonds between the -NH group of ZTO molecule (asdonor) and N atom of phen molecule (as acceptor). Thermal decomposition process is studied by applying thedifferential scanning calorimetry (DSC) and thermo thermogravimetric differential analysis (TG-DTG). TheDSC curve shows that there is one exothermic peak in ZTO·2H

Structural and Thermal Characteristics of a High-Nitrogen Energetic Material: G(AHDNE)

A high-nitrogen energetic salt, 1-amino-1-hydrazino-2,2-dinitroethylene guanidine salt [G(AHDNE)], was synthesized by reacting of 1-amino-1-hydrazino-2,2-dinitroethylene (AHDNE) and guanidine hydrochloride in sodium hydroxide aqueous solution. The theoretical investigation on G(AHDNE) was carried out by B3LYP/<TEX>$6-311+G^*$</TEX> method. The thermal behaviors of G(AHDNE) were studied with DSC and TG-DTG methods, and the result presents an intense exothermic decomposition process. The enthalpy, apparent activation energy and pre-exponential constant of the process are <TEX>$-1060J\;g^{-1}$</TEX>, <TEX>$148.7kJ\;mol^{-1}$</TEX> and <TEX>$10^{15.90}s^{-1}$</TEX>, respectively. The critical temperature of thermal explosion of G(AHDNE) is <TEX>$152.63^{\circ}C$</TEX>. The specific heat capacity of G(AHDNE) was studied with micro-DSC method and theoretical calculation method, and the molar heat capacity is <TEX>$314.69J\;mol^{-1}K^{-1}$</TEX> at 298.15 K. Adiabatic time-to-explosion of G(AHDNE) was calculated to be a certain value between 60-72 s. The detonation velocity and detonation pressure were also estimated. G(AHDNE) presents good performances.

Thermal behavior and combustion mechanism of high-nitrogen energetic materials DHT and BTATz

The thermal stability of 3,6-dihydrazino-1,2,4,5-tetrazine (DHT) and 3,6-bis(1H-1,2,3,4-tetrazol-5-ylimino)-1,2,4,5-tetrazine (BTATz) have been examined by isothermal and nonisothermal methods. The research conducted allow considering that the first stage of DHT decomposition is an unique, from viewpoint of thermal decomposition, redox process, in which tetrazine ring is reduced by hydrazine group forming diaminodihydrotetrazine and molecular nitrogen. In the case of BTATz, the decomposition begins with less thermostable tetrazole fragments, which captures the tetrazine ring also. The presence of preliminary reactions of isomerization during tetrazole ring decomposition is the reason for the large observable activation energy of decomposition (240.6kJ/mol or 57.5kcal/mol) in the temperature interval 250–334°C. In the combustion wave at higher temperatures, the activation energy of BTATz decomposition has considerably lower value (128.4kJ/mol or 30.7kcal/mol), which is close to theoretically calculated one.Burning characteristics of DHT and BTATz have been investigated. The temperature distribution in the combustion waves of DHT and BTATz have been measured at low pressures, which allows obtaining the surface temperature dependence vs. pressure. The research conducted allow considering that the burning of investigated compounds controls by a combustion model with leading reaction in the condensed phase.

A novel stable high-nitrogen energetic material: 4,4′-azobis(1,2,4-triazole)

A novel high-nitrogen compound with an N,N′-azo linkage, 4,4′-azobis(1,2,4-triazole), has been synthesized and well characterized. The solid-state structure was determined by X-ray diffraction. The experimentally determined density and enthalpy of formation matched with theoretically computed values based on the B3LYP method. The DSC result suggests that 4,4′-azobis(1,2,4-triazole) decomposes at a relatively high temperature (313.36 °C). By comparison with 3,3′-azobis(1,2,4-triazole), containing a C,C′-azo linkage, the N,N′-azo linkage was found to provide compounds with a relatively high density and high energy.

Influence of variable selection on partial least squares discriminant analysis models for explosive residue classification

Using a series of thirteen organic materials that includes novel high-nitrogen energetic materials, conventional organic military explosives, and benign organic materials, we have demonstrated the importance of variable selection for maximizing residue discrimination with partial least squares discriminant analysis (PLS-DA). We built several PLS-DA models using different variable sets based on laser induced breakdown spectroscopy (LIBS) spectra of the organic residues on an aluminum substrate under an argon atmosphere. The model classification results for each sample are presented and the influence of the variables on these results is discussed. We found that using the whole spectra as the data input for the PLS-DA model gave the best results. However, variables due to the surrounding atmosphere and the substrate contribute to discrimination when the whole spectra are used, indicating this may not be the most robust model. Further iterative testing with additional validation data sets is necessary to determine the most robust model.

Study on the synthesis and performance of 3,3′-azobis (6-amino-1,2,4,5-tetrazine)

The synthesis of high-nitrogen energetic material 3,3′-azobis (6-amino-1,2,4,5-tetrazine) (DAAT) from 3,6-bis (3,5-dimethylpyrazol-1-yl)-1,2,4,5-tetrazine by a four-step reaction is described. The thermal properties of DAAT were investigated by using Differential scanning calorimetry (DSC), Pressure differential scanning calorimetry (PDSC) and Thermogravimetry (TG) techniques. Kinetic parameters of decomposition and mechanism functions were obtained. The results showed that DAAT is thermally stable up to 283°C and gives an exotherm maximum at 320°C with ΔH of 1974.33 J·g−1, which is higher than HMX. The values of E a are 209.69 and 208.77 kJ·mol−1 by the methods of Kissinger and Ozawa, respectively. The decomposition rate of DAAT is sensitive to pressure and in direct proportion to atmosphere pressure. The explosive performances of DAAT were calculated theoretically by VLW equation-of-state (EOS) and the results showed that several explosive formulations based on DAAT have high-energy and insensitive performance.

3,3'-Azobis(6-amino-1,2,4,5-tetrazine): A Novel High-Nitrogen Energetic Material This work was supported at Los Alamos by the joint program of the Department of Defense and the Department of Energy for the preparation and characterization of new energetic materials, and at the Naval Research Laboratory by the Office of Naval Research, Mechanics Division.

3,3'-Azobis(6-amino-1,2,4,5-tetrazine): A Novel High-Nitrogen Energetic Material This work was supported at Los Alamos by the joint program of the Department of Defense and the Department of Energy for the preparation and characterization of new energetic materials, and at the Naval Research Laboratory by the Office of Naval Research, Mechanics Division.