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This review discusses the recent advances in the syntheses of high explosive energetic materials. Syntheses of some relevant modern primary explosives and secondary high explosives, and the sensitivities and properties of these molecules are provided. In addition to the synthesis of such materials, processing improvement and formulating aspects usi...
Citations
... Among these compounds, 30 and 34 were the best replacements for the primary explosives (Scheme 2) [64]. Compared to the lead-based Ems [65], this silver salt is obviouly less toxic. A novel high-nitrogen methylene and azo linked mixed azole 41 was prepared by simple reactions as well as the methylene bridged azole molecule 40, which was not just easily converted to its salts 42 − 44 but also could be applied as a starting material to synthesize a nitroimino involved azole 45 and its energetic salts 46 − 48 (Scheme 3). ...
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.
Graphical Abstract
... For example, the detonation velocity has increased only 30% over the last century from TNT to HMX and CL-20, which are considered to be representations of the first, second, and third generations of EMs, respectively. Despite the development of various new EMs, their comprehensive properties can hardly outperform [5][6][7][8][9]. The reason for the slow evolution can be attributed to the composition limitation of CHON elements [10], the energy − safety contradiction [11][12][13], the low-efficiency design and synthesis, and the multiple and strict requirements for use [4]. ...
A new energetic co-crystal of trinitrotoluene (TNT) and pyrene (PYRN) with a 1:1 molar ratio was prepared by a slow solvent evaporation technique. Co-crystal physicochemical properties have also been examined using optical microscopy, powder X-ray diffraction, single crystal X-ray diffraction, and differential scanning calorimetry. The results of single-crystal X-ray diffraction and non-covalent interaction calculations showed that non-covalent interactions (donor-acceptor π-π interaction) govern the structures of the TNT:PYRN co-crystal. The experimental and theoretical outcomes supported each other in the study. Thermal stability, impact sensitivity, and detonation performance of the co-crystal were investigated. DSC measurement indicates that the co-crystal has a melting point of 167 °C and a decomposition temperature of 293 °C, indicating outstanding thermal stability. The co-crystal was found to be less impact-sensitive than TNT using the BAM fall hammer instrument. Furthermore, the calculated detonation velocity and detonation pressure of the co-crystal are 5.29 km·s −1 and 8.48 G Pa, respectively. As an outcome, the TNT:PYRN co-crystal may be a promising intermediate energy explosive with low sensitivity and, as such, may be a desirable explosive alternative in the future instead of TNT for low-vulnerability formulations.
... This captures the essence of the synthesis challenge [8][9][10][11]. With the recent introduction of cocrystallization to the EMs community, a different approach to producing better and safe energetics without chemical synthesis has been presented, with the aim of partially resolving this issue [12][13]. ...
A new energetic co-crystal of trinitrotoluene (TNT) and pyrene (PYRN) with a 1:1 molar ratio was prepared by a slow solvent evaporation technique. Co-crystal physicochemical properties have also been examined using optical microscopy, powder X-ray diffraction, single crystal X-ray diffraction, and differential scanning calorimetry. The results of single-crystal X-ray diffraction and non-covalent interaction calculations showed that non-covalent interactions (donor-acceptor π-π interaction) govern the structures of the TNT: PYRN co-crystal. The experimental and theoretical outcomes supported each other in the study. Thermal stability, impact sensitivity, and detonation performance of the co-crystal were investigated. DSC measurement indicates that the co-crystal has a melting point of 167°C and a decomposition temperature of 293°C, indicating outstanding thermal stability. The co-crystal was found to be less impact-sensitive than TNT using the BAM fall hammer instrument. Furthermore, the calculated detonation velocity and detonation pressure of the co-crystal are 5.29 km. s ⁻¹ and 8.48 G Pa, respectively. As an outcome, the TNT: PYRN co-crystal may be a promising intermediate energy explosive with low sensitivity and, as such, may be a desirable explosive alternative in the future instead of TNT for low-vulnerability formulations.
... The beginning of the intensive development of aviation and rocket technologies, including space exploration, and the development of drilling and blasting techniques (the intensification of the quarrying of natural resources) [1], all that in the early 1960s, created the need for energetic materials (EMs) with relatively high thermal and chemical stability and safe to store, handle and use [1][2][3][4]. Especially military explosives and EMs have changed significantly in this sense over the last thirty years, primarily due to the inclusion of new operational requirements such as insensitive munitions (IMs) [1,5], further due to the availability of newly synthesized high-energetic materials (HEMs) [1,4,5] and, last but not least, also due to the efforts to replace some very toxic EMs, for example 2,4,6-trinitrotoluene (TNT), with 2,4-dinitroanisole (DNAN) [6,7] or the potentially cancer-causing 1,3,5-trinitro-1,3, 5-triazinane (RDX) [8] with dihydroxylammonium 5,5 ′ -bistetrazole-1, 1 ′ -diolate (TKX-50) [9]. ...
... The beginning of the intensive development of aviation and rocket technologies, including space exploration, and the development of drilling and blasting techniques (the intensification of the quarrying of natural resources) [1], all that in the early 1960s, created the need for energetic materials (EMs) with relatively high thermal and chemical stability and safe to store, handle and use [1][2][3][4]. Especially military explosives and EMs have changed significantly in this sense over the last thirty years, primarily due to the inclusion of new operational requirements such as insensitive munitions (IMs) [1,5], further due to the availability of newly synthesized high-energetic materials (HEMs) [1,4,5] and, last but not least, also due to the efforts to replace some very toxic EMs, for example 2,4,6-trinitrotoluene (TNT), with 2,4-dinitroanisole (DNAN) [6,7] or the potentially cancer-causing 1,3,5-trinitro-1,3, 5-triazinane (RDX) [8] with dihydroxylammonium 5,5 ′ -bistetrazole-1, 1 ′ -diolate (TKX-50) [9]. ...
... The acquisition of new HEMs that exhibit balanced safety and energetic properties (non-sensitive explosives), however, is more and more time-consuming and technologically complicated [4,10]; it seems that the use of chemical methods in this area is approaching their limit. One of the most frequent ways to circumvent these problems is the application of crystal engineering methods, widespread for a long time in pharmaceutical chemistry and technology [11]. ...
The thermolysis of the co-agglomerates (CACs) of the attractive nitramines RDX, BCHMX, HMX and CL-20 with
1,3-diamino-2,4,6-trinitrobenzene (DATB) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) was studied by
means of differential thermal analysis (DTA) and differential scanning calorimetry (DSC), using the Kissinger
method for output evaluation. The insertion of both DATB and TATB molecules into nitramine crystal lattices
markedly increased the thermal sensitivity of the resulting CACs to overheating. Depression in melting points
was detected in all CACs and, with the exception of RDX CACs, also in the exothermic peaks. The RDX CACs differ
from the other studied CACs by their decomposition in the liquid state. The activation energies (Ea), obtained
correlate with asymmetric N-O stretching vibrations, confirming the important influence of ‒N‒O⋅⋅⋅⋅H‒H=
interactions in CACs; a similar correlation with asymmetric NO2 stretching confirms the interactions of DATB and
TATB molecules with nitramine molecules through van der Waals forces. The insertion of DATB or TATB into the
crystal lattice of HMX or CL20 changes their polymorphic modification from β- to δ- and in the latter case from ε-
to β- modifications in the corresponding CACs. The correlations of the Ea values with the square of detonation
velocity as a representative of performance and with the heat of combustion as a representative of the energy
content are consistent with already previously described relationships of this type, including exceptions for pure
nitramines.
... [12] Commonly, LS comes in two forms; normal lead styphnate (lead(II)-2,4,6-trinitro-benzene-1,3-diolate hydrate) and basic lead styphnate (di(lead(II) hydroxide)-2,4,6-trinitro-benzene-1,3diolate). [13] LS is easy to initiate and can be used in primer applications, but it is not as powerful as LA. Silver-based primary explosives (Silver azide) show good energetic performance, but they are not feasible for commercial uses due to high cost and sensitivity towards light. ...
The requirements for the chemical to act as a primary explosive, its importance, and the hazards associated with heavy‐metal‐based primary explosives are all well‐stated in this review. In addition, it outlined the limitations of the heavy‐metal‐free primary explosives already in use. This analysis underlines the importance of green primary explosives with updated information. It summarizes the possible candidates of metal‐free new generation green primary explosives, including their preparation routes, energetic properties, applications, and comparisons to traditional primary explosives. Furthermore, this analysis also aims to discuss the necessity for metal‐free primary explosives as well as the significant problem of replacing traditional primary explosives. This article briefly discusses the health and environmental hazards of poisonous heavy metal ions, which are an important part of many traditional primary explosives. Additionally, it reviews the synthesis, energetic and physicochemical properties of numerous potential energetic materials as ‘Metal‐free‐green primary explosives’. The analysis of heavy‐metal‐based, potassium‐based, and metal‐free primary explosives is carried out in terms of their synthesis, safety, physiochemical and energetic properties, initiation ability, and environmental impact.
... A significant trend is that energetic materials need to have higher detonation performance and lower sensitivity. With the in-depth study of high energy and insensitive explosives, the influence of crystal shape, crystal surface state, and crystal internal defects on the performance of explosives has attracted wide attention from researchers [6][7][8][9][10][11][12][13]. Compared to the explosive crystals in the form of flakes and needles, spherical explosives can significantly increase the charge density and improve the detonation performance of the charge. ...
To simulate the crystal morphology of β-HMX crystallized in the presence of different polymer additives in the solution, a modified attachment energy model was used to simulate the crystal morphology of β-HMX recrystallized in PVA-DMSO solution when the mass fractions of PVA were 0.5%, 1%, 3%, 5%, and 10%, respectively. When the mass fraction of additive was 10%, the simulation results were in good agreement with the experiment. Molecular dynamics simulations were performed on the solution systems of different types of polymer additives to predict the morphology of β-HMX crystals. In addition, the effect of water on the crystal morphology of β-HMX was studied, and the effect of additive PVA on the solute and solvent diffusion ability during crystal crystallization was studied. The simulation results have certain reference significance in the crystallization process of β-HMX under additive conditions.
... Therefore, the demand for new insensitive munition is increasing, and the thermodynamic and -kinetic behavior of new HEDM decomposition has gradually become a research hotspot. 20,21 The study of the thermal decomposition reaction mechanism and kinetic behaviors can help better understand the structure−performance relationship and the mechanism of combustion explosion of HEDMs under heat. 22 Therefore, the thermal decomposition of DNTF has been studied a lot. ...
When stimulated, for example, by a high temperature, the physical and chemical properties of energetic materials (EMs) may change, and, in turn, their overall performance is affected. Therefore, thermal stability is crucial for EMs, especially the thermal dynamic behavior. In the past decade, significant efforts have been made to study the thermal dynamic behavior of 3,4-bis(3-nitrofurazan-4-yl)furoxan (DNTF), one of the new high-energy-density materials (HEDMs). However, the thermal decomposition mechanism of DNTF is still not specific or comprehensive. In this study, the self-consistent-charge density-functional tight-binding method was combined with molecular dynamics (MD) simulations to reveal the differences in the thermal decomposition of DNTF under four heating conditions. The O–N (O) bond would fracture first during DNTF initial thermal decomposition at medium and low temperatures, thus triggering the cracking of the whole structure. At 2000 and 2500 K, NO2 loss on outer ring I is the fastest initial thermal decomposition pathway, and it determines that the decomposition mechanism is different from that of a medium-low temperature. NO2 is found to be the most active intermediate product; large molecular fragments, such as C2N2O, are found for the first time. Hopefully, these results could provide some insights into the decomposition mechanism of new HEDMs.
... 2,4,6-Trinitrotoluene (TNT) and dinitroanisole (DNAN) are two kinds of widely investigated and applied melt cast materials. However, their further applications are limited by their relative shortcomings, such as the toxicity and environmental problems of TNT [3,4] and low detonation performances of DNAN [5,6]. Therefore, there is continued interest in developing new melt cast materials with better explosive performances. ...
A new structural type for melt cast materials was designed by linking nitrotetrazole ring with 1,2,4-oxadiazole through a N-CH2-C bridge for the first time. Three N-CH2-C linkage bridged energetic compounds, including 3-((5-nitro-2H-tetrazol-2-yl) methyl)-1,2,4-oxadiazole (NTOM), 3-((5-nitro-2H-tetrazol-2-yl)methyl)-5-(trifluoromethyl)-1,2,4 -oxadiazole (NTOF) and 3-((5-nitro-2H-tetrazol-2-yl)methyl)-5-amine-1,2,4-oxadiazole (NTOA), were designed and synthesized through a two-step reaction by using 2-(5-nitro-2H-tetrazole -2-yl)acetonitrile as the starting material. The synthesized compounds were fully characterized by NMR (1H, 13C), IR spectroscopy and elemental analysis. The single crystals of NTOM, NTOF and NTOA were successfully obtained and investigated by single-crystal X-ray diffraction. The thermal stabilities of these compounds were evaluated by DSC-TG measurements, and their apparent activation energies were calculated by Kissinger and Ozawa methods. The crystal densities of the three compounds were between 1.66 g/cm3 (NTOA) and 1.87 g/cm3 (NTOF). The impact and friction sensitivities were measured by standard BAM fall-hammer techniques, and their detonation performances were computed using the EXPLO 5 (v. 6.04) program. The detonation velocities of the three compounds are between 7271 m/s (NTOF) and 7909 m/s (NTOM). The impact sensitivities are >40 J, and the friction sensitivities are >360 N. NTOM, NTOF and NTOA are thermally stable, with decomposition points > 240 °C. The melting points of NTOM and NTOF are 82.6 °C and 71.7 °C, respectively. Hence, they possess potential to be used as melt cast materials with good thermal stabilities and better detonation performances than TNT.
... Numerous energetic molecules are being prepared continuously worldwide; however, most of them cannot be used in real applications because of the stringent economic production, performance, stability, and sensitivity requirements [86][87][88][89]. A design approach employing the cocrystallization of energetic materials effectively achieves desirable physical and energetic properties due to their intimate association. ...
FOX-7 demonstrates a fascinating explosophoric motif with a unique combination of detonation performance and stability. Unlike classical explosives, such as TNT, TATB, and RDX, FOX-7 exhibits superior energetic performance originating from its high density, oxygen balance, and dinitro groups. Indeed, owing to its unique energetic properties and versatile molecular structure, a variety of neutral compounds and salts have been synthesized during the past two decades and continuing. These materials comprise NH2 and NO2 groups on the C=C bond as an integral structural unit that provides an opportunity for a diverse blend of physical and detonation properties. This critical review summarizes several synthetic strategies used for structural modification of FOX-7 and highlighted their energetic properties. Due to the chemically tailorable framework, synthetic accessibilities, and superior energetic characteristics, FOX-7 is subjected to intense and expansive research and is undoubtedly considered a promising precursor for developing new explosives, propellants, and pyrotechnics.
... 6, and 9), one fluorides (coformer 2), one triazole derivatives (coformer 10) and three energetic molecules only containing C, H, O, and N atoms (coformers 5,7,8). Considering usually high sensitivity of the peroxides 73,74 and the requirement to environmental safety for modern explosives 75,76 . we first exclude the six coformers involving the peroxides and fluorides (cofomers 1, 2, 3, 4, 6, and 9) in the subsequent experiment on co-crystalization with CL-20. ...
Cocrystal engineering have been widely applied in pharmaceutical, chemistry and material fields. However, how to effectively choose coformer has been a challenging task on experiments. Here we develop a graph neural network (GNN) based deep learning framework to quickly predict formation of the cocrystal. In order to capture main driving force to crystallization from 6819 positive and 1052 negative samples reported by experiments, a feasible GNN framework is explored to integrate important prior knowledge into end-to-end learning on the molecular graph. The model is strongly validated against seven competitive models and three challenging independent test sets involving pharmaceutical cocrystals, π–π cocrystals and energetic cocrystals, exhibiting superior performance with accuracy higher than 96%, confirming its robustness and generalization. Furthermore, one new energetic cocrystal predicted is successfully synthesized, showcasing high potential of the model in practice. All the data and source codes are available at https://github.com/Saoge123/ccgnet for aiding cocrystal community. Experimental determination of new cocrystals remains challenging due to the need of a systematic screening with a large range of coformers. Here the authors develop a flexible deep learning framework based on graph neural network demonstrated to quickly predict the formation of co-crystals.
