Over the past century, the search for lead-free, environmentally friendly initiating substances has been a highly challenging task in the field of energetic materials. Here, an organic primary ...explosive featuring a fused-ring structure, 6-nitro-7-azido-pyrazol3,4-d1,2,3triazine-2-oxide, was designed and synthesized through a facile two-step reaction from commercially available reagents. This organic initiating substance meets nearly all of the stringent criteria of environmentally friendly primary explosives for commercial applications: it is free of toxic metals and perchlorate, has a high density, high priming ability, unusual sensitivities towards non-explosive stimuli, excellent environmental resistance, decent thermal stability, high detonation performance, satisfactory flowability and pressure durability, and is low-cost and easy to scale-up. These combined properties and performance measures surpass the current and widely used organic primary explosive, DDNP. The fused-ring organic primary explosive reported herein may find real-world application as an initiating explosive device in the near future.
Owing to its simple preparation and high oxygen content, nitroformate
C(NO
)
, NF is an extremely attractive oxidant component for propellants and explosives. However, the poor thermostability of ...NF-based derivatives has been an unconquerable barrier for more than 150 years, thus hindering its application. In this study, the first example of a nitrogen-rich hydrogen-bonded organic framework (HOF-NF) is designed and constructed through self-assembly in energetic materials, in which NF anions are trapped in pores of the resulting framework via the dual force of ionic and hydrogen bonds from the strengthened framework. These factors lead to the decomposition temperature of the resulting HOF-NF moiety being 200 °C, which exceeds the challenge of thermal stability over 180 °C for the first time among NF-based compounds. A large number of NF-based compounds with high stabilities and excellent properties can be designed and synthesized on the basis of this work.
Abstract
A primary explosive is an ideal chemical substance for performing ignition in military and commercial applications. For over 150 years, nearly all of the developed primary explosives have ...suffered from various issues, such as troublesome syntheses, high toxicity, poor stability or/and weak ignition performance. Now we report an interesting example of a primary explosive with double perovskite framework, {(C
6
H
14
N
2
)
2
Na(NH
4
)(IO
4
)
6
}
n
(
DPPE-1
), which was synthesized using a simple green one-pot method in an aqueous solution at room temperature.
DPPE-1
is free of heavy metals, toxic organic components, and doesn’t involve any explosive precursors. It exhibits good stability towards air, moisture, sunlight, and heat and has acceptable mechanical sensitivities. It affords ignition performance on par with the most powerful primary explosives reported to date.
DPPE-1
promises to meet the challenges existing with current primary explosives, and this work could trigger more extensive applications of perovskite.
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.
This study presents the synthesis of 5,6-fused bicyclic conjugated energetic compounds through a combined strategy of anchoring the catenated nitrogen-atom chain and introducing vicinal C-amino and ...C-nitro groups into a tetrazolo-pyridazine ring. Their crystal structures were confirmed by single crystal X-ray diffraction. Both compounds display good thermal stability, high energetic properties and low sensitivities as energetic materials.
Two 5,6-fused tetrazolo-pyridazine compounds were synthesized and characterized, which exhibited high thermal stability, excellent energetic properties and low mechanical sensitivity.
Energetic substances with layered crystal packing have been identified as the most promising next-generation high-energy materials (HEMs) due to their excellent insensitivity. The challenge, however, ...is how to design layered HEMs. In this study, a novel strategy called “acceptor–donor separation” was proposed to control the layer-by-layer stacking of energetic molecules through directional hydrogen boding: that is, a hydrogen bond donor and acceptor are located in different energetic segments and at least one of them has a conjugated planar structure, which will enable the energetic fragments to be infinitely extended in a two-dimensional plane to form a target layered structure. The experimental results showed that three exemplary substances designed by using this strategy possess the expected layered structures, which have been confirmed by single-crystal X-ray diffraction, demonstrating the robustness of this strategy. Moreover, the three as-synthesized HEMs all exhibit excellent insensitivity (impact sensitivity IS > 40 J; friction sensitivity FS > 360 N), affording safety far beyond those of the most powerful HEMs in use today. Especially, the hydroxylammonium energetic salts possess good detonation performance (detonation velocity D = 8924 m s–1; detonation pressure P = 36.9 GPa) comparable to that of 1,3,5-trinitro-1,3,5-triazine (RDX), one of the most powerful high explosives in use today.
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•A new strategy to stabilize copper azide (CA) by hydrogen bonding is proposed.•The stability (or safety) of CA are improved obviously through the new strategy.•The synthesis of newly ...reported CA-based igniting substances is very simple.•The newly reported CA-based substances show powerful initiation capability.
The development of high-performance initiating explosives through energetic complexes is considered a feasible way to satisfy military and civilian applications. Compared with other reported initiating explosives, copper(II)-azide is a more promising candidate due to its stronger initiation ability and green nature. However, its instability towards mechanical and electrostatic stimulation hinders its application. This study aimed to propose an effective strategy for stabilizing highly sensitive and explosive copper(II)-azide via hydrogen bonding with NH2-substituted ligands. Using this method, two highly energetic polymers, Cu(MAT)(N3)2n (CMA-1) and Cu4(MAT)2(N3)8(H2O)n (CMA-2), based on 1-methyl-5-aminotetrazole (MAT), were synthesized and confirmed by single-crystal x-ray diffraction. The experimental results showed that both CMA-1 and CMA-2 had improved thermal stability and reduced mechanical and electrostatic sensitivities to meet practical applications, demonstrating the feasibility of stabilizing the copper(II)-azide system through hydrogen bonds. Especially, combining a series of advantages, including nontoxic metal (Cu), high nitrogen content (62.5%), high thermal decomposition temperature (223.3 °C), good sensitivities (impact sensitivity = 1.0 J; friction sensitivity = 30 N; electrostatic spark sensitivity = 201.6 mJ), powerful ignition capability (minimum primary charge = 10 mg), and simple synthesis, CMA-2 exhibited comprehensive performance beyond those of all other initiating substances to date. In particular, the electrostatic spark sensitivity (201.6 mJ) is at least 720 times higher than that of the original CA powder (<0.28 mJ), making it a promising candidate for new-generation initiating explosive.
Energetic metal–organic frameworks (E-MOFs) have witnessed increasing development over the past several years. However, as a highly energetic cation, NH3OH+ has never been explored to construct ...transition-metal-based E-MOFs. Herein, we report the first examples of NH3OH+-containing E-MOFs with bis(tetrazole)methane (H2btm) as a ligand and copper and manganese as central metal ions, (NH3OH)2(Cu(btm)2) n and (NH3OH)2(Mn(btm)2) n . Crystal structure determinations reveal that both E-MOFs show two-dimensional layered structures. Experimental results suggest that they have high thermal decomposition temperatures (>200 °C). Among them, Cu-based E-MOFs possesses outstanding thermal stability (T dec = 230.3 °C), which surpasses those of known NH3OH+-containing compounds. They also have high energy density; in particular, the Cu-based E-MOF affords a high heat of combustion (11447 kJ kg–1) and high heat of detonation (713.8 kJ mol–1) beyond the most powerful organic explosives in use today. Additionally, the two E-MOFs show completely different sensitivity properties: the Mn-based E-MOF is an insensitive high-energy-density material (IS > 40 J; FS > 360 N; EDS > 20 J), while the Cu-based E-MOF can be classified as a sensitive energetic material (IS = 13 J; FS = 216 N; EDS = 10.25 J), demonstrating their diverse applications in different fields. Our research proposes a unique class of high-energy-density materials.
To develop environmentally friendly high-energy-density materials with outstanding detonation performances, anionic metal–organic frameworks (anionic MOFs) are introduced into the area of energetic ...materials. In this work, two anionic complexes, (AG) 3 (Co(btm) 3 ) ( 1 ) and {(AG) 2 (Cu(btm) 2 )} n ( 2 ) (H 2 btm = bis(tetrazole)methane, AG = aminoguanidinium), have been prepared and characterized by single-crystal X-ray diffraction analysis. Theoretical analyses predict that these two anionic energetic MOFs should show extensive hydrogen bonding with remarkably high nitrogen contents, good thermal stabilities, favorable insensitivities, and excellent detonation performances, and this has been confirmed by experimental results. Notably, the heats of detonation of 1 (4.75 kcal g −1 ) and 2 (5.41 kcal g −1 ) are far superior to those of all hitherto reported MOF-based high-energy-density materials.
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•Thermal decomposition and combustion of stearic acid were conducted and simulated.•Three flame propagation stages of stearic acid combustion were divided in detail.•Initial ...decomposition and main products of stearic acid combustion were depicted.•Effects of density, temperature, and oxygen content on the combustion were probed.•Combustion mechanism of stearic acid was established by combined flame propagation.
To better look into the thermal decomposition and combustion progress of stearic acid (C18H36O2), the experimental tests and Reaction Force Field (ReaxFF) molecular dynamics simulation were conducted. Also, an investigation into the flame propagation characteristics and the reaction mechanisms of stearic acid was explored under different conditions. The thermal decomposition activation energy of stearic acid obtained by the TG tests was 105.01 kJ/mol. This is consistent with the initial decomposition stage reaction activation energy calculated to be 94.273 kJ/mol in the simulation. The flame propagation process of stearic acid combustion was explored and involved three stages: the flame growth stage, the stable flame stage, and the flame decay stage. The flame growth stage was subdivided into the flame growth inside the tube, upper the tube, and mushroom-shaped cloud. Besides, the flame growth stage could correspond to three flame propagation velocity peaks. Furthermore, the simplified reaction mechanism scheme for stearic acid radicals could explain the macro flame propagation behaviours. The main reaction pathway through which the C18H36O2 molecules were decomposed into C2H4 and C2H3, C2H5, and other free radicals was found to correspond to the initial flame growth stage, and the flame decay stage was dominated by the generation of final reaction products (H2O, CO2, and CO2, etc.). Concerning the overall reaction mechanism, the unburned stearic acid was continuously ignited, and the combustion products were continuously generated at the same time, thereby corresponding to the stable flame propagation stage. According to the flame propagation process and the simulation results, combustion reaction mechanisms of stearic acid were constructed.
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