TKX-50研究进展

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

TKX-50 represents a promising energetic material with good thermal stability, performance, and insensitivity. As one of its most important thermophysical properties, the thermal conductivity of TKX-50 plays a critical role in determining its thermal stability. However, measuring the thermal conductivity κ of explosives can be extremely difficult and dangerous. In this study, we employ non-equilibrium molecular dynamics (NEMD) simulations to investigate the heat transfer characteristics of TKX-50 crystals and their composite systems incorporating various thermal conductive fillers (TCFs). Our simulations reveal that pure TKX-50 exhibits a thermal conductivity of approximately 0.5 W/(m·K), comparable to conventional high explosives. Importantly, for composite systems with TCFs, we observed significant interaction variations with graphene depending on the orientation angle between the N-oxide group of TKX-50 and the inserted graphene layer, which may substantially affect the thermal conductivity of the composite system. Notably, we reported exceptionally high thermal conductivity when the graphene layer was aligned perpendicular to both the N-oxide group and the heat flux. These findings are further supported by phonon spectrum analysis and modeled using the series-parallel heat conduction framework. Our study provides a fundamental understanding of thermal transport mechanisms in TKX-50-based systems and offers new insights for designing highly efficient TCFs to improve the thermal management of energetic materials.

ABSTRACT CL-20, as the best comprehensive high nitrogen energetic material, plays an important role in weaponry, equipment, and national defense. TKX-50, as a new type of ionic explosive, is commonly used for composite explosives due to its excellent desensitization effect. This work combines TKX-50 and CL-20, and then encapsulates them using demulsification method. TKX-50/CL-20 composite explosives were successfully prepared at the binder dosage of only 1.5 wt.%, which showed good encapsulation effects. The results showed that the Polyvinyl butyraldehyde (PVB) and wax were successfully coated on the surface of the explosive particles, and the crystal structure of CL-20 in the composite did not change, while the excellent detonation property of ε-CL-20 is retained. Our study found that TKX-50 has a catalytic effect on the decomposition of CL-20, and when mixed alone, the activation energy of CL-20 is significantly reduced. Furthermore, the activation energy of the TKX-50/CL-20 composite explosive prepared has hardly changed compared to CL-20, and it has better thermal stability compared to TKX-50/CL-20 (1:1). The impact sensitivity and friction sensitivity of TKX-50/CL-20 composite explosives have also been significantly improved, with 2 J and 96 N higher than the TKX-50/CL-20 (1:1) raw materials, respectively, demonstrating good desensitization effect.

No abstract available

No abstract available

During the process of external work, the energy of the negative oxygen balanced 5,5′‐Bi‐tetrazolium‐1,1′dioxyhydroxylammonium salt (TKX‐50) is not fully released, resulting in low energy utilization efficiency and the generation of harmful gases that pollute the environment. Based on this, in order to adjust the oxygen balance of TKX‐50, nano TKX‐50/AP composites with positive, zero and negative oxygen balance were prepared by emulsion method. The morphology of nano TKX‐50/AP composite was similar to that of hedgehog‐like spherical‐like particles, with many dense pores formed on the surface, and the average particle size was about 30 μm. During the composite process, part of TKX‐50 reacted with AP to form 5,5′‐bistetrazole‐1,1′dioxidamide (ABTOX). The first thermal decomposition peak temperature of zero‐oxygen balance TKX‐50/AP composite was 236.0°C, which was slightly reduced compared with that of TKX‐50. The second thermal decomposition peak temperature was 275.1°C, which was 22.2°C higher than that of TKX‐50. The heat release of zero‐oxygen balance TKX‐50/AP composite reached 2206 J g−1, which increased by 35.9% compared to TKX‐50, and the energy utilization efficiency was also greatly improved. The drop height of 50% explosion probability (H50) of zero‐oxygen balance TKX‐50/AP composite was 63.5 cm, and the explosion probability of friction sensitivity was 72%. Compared with TKX‐50, it increased by 15.1 cm and decreased by 28%, respectively. The results showed that the mechanical safety performance of TKX‐50 had been improved.

For the sake of exploring the decomposition characteristics and kinetic of nitrocellulose and TKX-50 mixtures, Friedman, KAS, and OFW kinetic analysis methods were used to investigate the mixture of nitrocellulose and TKX-50 mixtures. It shows that nitrocellulose and TKX-50 promote each other during the thermal decomposition process. Therefore, this study provides a reference for NC-A and TKX-50 in the application field of explosives.

No abstract available

In order to achieve new energetic materials with high energy, low sensitivity, and moisture-proof properties, dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50)/ammonium perchlorate (AP) cocrystal (molar ratio 1:1) was successfully prepared through a spray-assisted solvent–nonsolvent method. SEM shows that the morphology of the cocrystal is different from those of the two raw materials. XRD and FT-IR spectra indicate the formation of the cocrystal. The apparent activation energy of the cocrystal is lower than that of raw TKX-50. The characteristic drop height (H50) is higher than that of TKX-50, while the friction sensitivity (P) of the cocrystal is lower. In addition, the moisture-proof property of the cocrystal is improved, showing good application potential.

Based on the feasibility of the combination of dihydroxylammonium-5,5′-bistetrazolyl-1,1′-diolate (TKX-50) and ammonium perchlorate (AP) determined by molecular dynamics simulations, TKX-50-AP composites were prepared using the solvent-non-solvent method. The ignition and combustion pressure characteristics of four materials, namely, TKX-50, AP, TKX-50-AP mixture, and TKX-50-AP composite, were comparatively studied using a self-designed annular ignition combustion device and a 100 mL closed burst apparatus. Combined with the results of thermal analysis and mass spectrometry, the reaction characteristics of the TKX-50-AP composites were discussed. The results showed that AP could be uniformly coated on the surface of TKX-50 crystals through recrystallization, forming spherical or ellipsoidal TKX-50-AP composites with a relatively stable core–shell structure. Compared to the TKX-50-AP mixture, the mechanical sensitivity of the composite significantly reduced. The main growth crystal planes of TKX-50 and AP primarily interacted through hydrogen bonds. After the composite of TKX-50 and AP was formed, its combustion performance was evaluated and determined to be better than those of both the raw materials (TKX-50 and AP) and the TKX-50-AP mixture. Further, it exhibited the same high burn rate as TKX-50 while improving gas release during combustion. Compared to the TKX-50-AP mixture, under plasma initiation, AP in the TKX-50-AP composite could react more fully with the C, H, O, and N elements in TKX-50, thereby improving the reaction characteristics of TKX-50.

1,1’-dihydroxyl-5,5’-ditetrazolium dihydroxylamine salt(TKX-50) is a new energetic ionic salt which has attracted wide attention at present. This paper reviews the research progress of TKX-50, including TKX-50 simple explosive and TKX-50 base mixed explosive. TKX-50 has certain application potential due to its advantages of easy synthesis, high energy, low mechanical sensitivity and low toxicity. However, compared with traditional CHNO energetic materials, TKX-50’s different crystal composition, interactions between particles in the crystal, thermal properties and its intrinsic nature, its less than ideal thermal stability and compatibility will limit its application. This indicates that the thermal response mechanism and energy release mechanism of the energetic ionic salt represented by TKX-50 May be different from that of traditional CHNO energetic materials, which needs further study.

As a representative of the new generation of high-energy explosives, TKX-50 has attracted widespread attention due to its remarkably low sensitivity toward shock. However, the reported decomposition barriers of TKX-50 (∼37 kcal mol-1) are comparable to those of commonly used explosives. The mechanism of its low shock sensitivity remains unclear. In this study, using an ab initio molecular dynamics method combined with a multiscale shock simulation technique and transition state calculations (at the B2PLYP-D3/Def2TZVP level), we discovered an unconventional reaction pathway of TKX-50 under shock, and its rate-controlling step is the dissociation of the hydroxyl radical (OH) from the anion ring after proton transfer, followed by ring rupture and the production of H2O and N2. The barrier for this OH dissociation reaction is as high as 51.9 kcal mol-1. In contrast, under thermal stimuli, TKX-50 prefers to open rings directly after proton transfer without losing the OH. The corresponding barrier is 35.4 kcal mol-1, which is in good agreement with previous studies. The reason for the unconventional reaction pathway of TKX-50 under shock may be the suppression of anion ring opening in thermal decomposition by steric hindrance upon shock compression. In addition, the dominant N2 generation pathway under shock releases less energy than pyrolysis which further explains the low shock sensitivity of TKX-50. This study comprehensively elucidates the different reaction mechanisms of TKX-50 under thermal and shock conditions and proposes a crucial reaction pathway leading to its low shock sensitivity. These findings will contribute to the understanding and application of tetrazole anionic energetic salts.

BACKGROUND 5,5'-bistetrazole-1,1'-diolate (TKX-50), known as a novel explosive, is characterized by its high energy and low sensibility. It is a preferred explosive for criminals to carry out illegal attacks, posing a significant security risk. Therefore, the development of an efficient and highly specific detection method for TKX-50 is of significant practical importance. Fluorescent chemical sensors have demonstrated tremendous potential in explosive detection due to their high sensitivity, rapid response, and visual detection capabilities. RESULTS A novel fluorescent chemical sensor N'-((E)-5-((E)-2-(3-(dicyanomethylene)-5,5-dimethylcyclohex-1-en-1-yl)vinyl)-2-hydroxybenzylidene)-7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide (EXF) was designed and synthesized, and its structure was characterized by 1H NMR, 13C NMR, and HRMS. The sensor can achieve continuous and specific detection of Cu2+ and TKX-50 through the 'on-off-on' fluorescence response. The EXF achieved a detection limit of 0.0968 μM for Cu2+. The complex [EXF-Cu2+] could specifically identify the novel explosive TKX-50 among a variety of explosives tested, with a detection limit of 0.0648 μM. In this study, the qualitative detection of Cu2+ and TKX-50 was carried out using test strips, and the quantitative determination of Cu2+ and TKX-50 in real water samples was successfully achieved based on the standard curve of a smartphone. Additionally, EXF can be used for the visualization of latent fingerprints (LFPs), demonstrating its potential application in the field of criminal investigations. The application of EXF for Cu2+ and TKX-50 imaging in living cells is also demonstrated. SIGNIFICANCE The fluorescent sensor EXF establishes a connection between explosive detection and ion sensing by utilizing Cu2+ as a "bridge". This research not only provides innovative explosive detection technologies, but also offers valuable design principles for multifunctional fluorescent sensors. The test strips and smartphone platform have preliminarily achieved on-site rapid qualitative and quantitative detection. And the LFPs imaging and detection in living cells further expand the application field, which has significant practical application value.

No abstract available

ABSTRACT Dihydroxylammonium 5, 5′-bistetrazole-1, 1′-diolate (TKX-50) is a promising new nitrogen-rich energetic material with considerable properties and low sensitivity, but unfortunately inadequate energy release may restrict its application. To enhance the reactivity of TKX-50 in the energetic materials, TKX-50/CL-20 composite material was constructed by using a facile fabrication method. Further, thermal decomposition analysis, constant-volume combustion cell test and laser ignition experiment were conducted to study the thermal behavior. The results showed that the incorporation of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12 -hexaazaisowurtzi-tane (CL-20) advanced the exothermic peak temperature for the decomposition of TKX-50, and significantly reduced the apparent activation energy obtained by the thermal decomposition kinetic methods. Moreover, CL-20 could promote the combustion and energy release rate of TKX-50 that is reflected on the increased pressurization rate, as well as the stronger and brighter flame that appeared during the combustion process. The obtained results indicated that CL-20 participated in the thermal behavior of TKX-50 and improved its overall reactivity.

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

Abstract Dihydroxyl ammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) is a newly explosive material attracting researchers, but the sensitive orientation is out of research in theory. First-principles calculated phonons and electrons are attempted to find the sensitive orientation of TKX-50 and of its derivatives. To discuss the sensitive degree of electrons, the bandgap and effective mass are calculated from electron density states. The phonons are calculated from dynamic matrix to discuss the sensitively vibrational orientation of bonds, revealing the optically sensitive directions in [1 0 0] and [0 1 0]. Also, the mechanical properties are listed from elastic constants to show the resistances to deformation corresponding to the sensitivity under impact.

ABSTRACT In this work, two TNBA-based low eutectic mixtures, TNBA/TNAZ (TZ) and TNBA/DNTF (TD), as well as eight TNBA-based melt-cast explosives, TNBA/TNAZ/RDX (TZR), TNBA/TNAZ/HMX (TZH), TNBA/TNAZ/TKX-50 (TZT), TNBA/TNAZ/CL-20 (TZC), TNBA/DNTF/RDX (TDR), TNBA/DNTF/HMX (TDH), TNBA/DNTF/TKX-50 (TDT) and TNBA/DNTF/CL-20 (TDC), were developed as structural models. A molecular dynamics approach was used to model the cohesive energy density, binding energy, and mechanical properties of these explosives. Moreover the thermal decomposition properties and mechanical sensitivity were characterized via DSC and mechanical sensitivity tests. Finally, the EXPLO-5 software predicted the detonation properties and detonation products of the aforementioned 10 mixed explosive systems. The results showed that the four mixed explosives of TDT, TDH, TZC, and TDR had excellent performance in cohesive energy density, binding energy, and material rigidity, respectively. The temperature difference was comparatively significant between the melting temperature and decomposition temperature of the eight types of mixed explosives, up to 170.60 K, with TDH and TZH having the highest thermal decomposition temperature at approximately 520 K. The six kinds of mixed explosives of TZR, TZH, TZT, TDR, TDH, and TDT had moderate mechanical sensitivities. . The five types of mixed explosives, TZT, TZC, TDH, TDT, and TDC, had the greatest detonation velocity.

Aluminum-containing explosives are characterized of a high detonation heat and a long work duration, making them suitable for causing internal explosive damage to targets such as runway. The reaction rate of aluminum during the explosion process will affect the energy output process of the explosive, thereby affecting the destructive effect on the runway. In order to study the damage law of aluminum reaction rate on runway targets, this paper takes TKX-50 based aluminum explosive (TAE) as an example and uses finite element software to simulate the explosion process of the charge inside the runway. A systematic study was conducted on the explosion process and mechanism of aluminum-containing explosives with different aluminum reaction rates in the runway from the perspectives of damage process and energy transfer. Research has shown that during the stress wave failure stage, increasing the aluminum reaction rate can effectively increase the stress wave energy, enabling it to form a larger range of failure in the runway. In the stage of gas expansion, the reaction rate of aluminum directly affects the process of gas pressure attenuation in the cavity, thereby affecting the work ability of the product on the runway. When the aluminum reaction rate coefficient is a=5e-4, the aluminum reaction rate matches the gas leakage rate, allowing the heat energy released by the aluminum reaction to effectively compensate for the internal energy loss caused by gas leakage, slowing down the rate of gas pressure attenuation, and causing greater damage to the runway. In addition, the law of the influence of aluminum reaction rate on the effect of explosive damage in the runway is well adapted under different conditions of charge quality and burial depth.

No abstract available

High-efficiency explosives that combine high stability and excellent energy performance are one of the key directions of energetic materials research. In this study, a novel monocyclic hydroxytetrazole derivative (3) with high stability was prepared, and a series of insensitive energetic ionic salts were derived from it. Benefiting from their outstanding performance in terms of density, 3D hydrogen bonding and π-electron interactions, these salts are excellent in both detonation performance (D = 8709 to 9314 m s-1 and P = 29.9 to 35.6 GPa) and thermal stability (Td = 193.0-232.2 °C). The hydrazine salt (2) exhibits high detonation properties (D = 9314 m s-1 and P = 35.6 GPa), due to its high density (ρ = 1.71 g cm-3) and high heat of formation (ΔfH = 563.2 kJ mol-1 = 3.19 kJ g-1). In addition, the high thermal stability (Td = 232.0 °C) and low mechanical sensitivity (IS = 30 J and FS = 360 N) of 2 are also unmatched by HMX and TKX-50. These improved properties demonstrate the great promise of 2 as an insensitive high-energy explosive.

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

5,5'-Bitetrazole-1,1'-dioxydihydroxylamine salt (TKX-50), a high-energy energetic material, possesses good safety and energy properties. The energy characteristic data of TKX-50 are commonly generated via theoretical simulation and experimental measurements. Interestingly, the detonation velocity of TKX-50 is higher than HMX, but the specific kinetic energy of TKX-50 is the opposite. Thus, a systematic study on the decomposition mechanism of TKX-50 is important to establish the reasons for this variation in specific kinetic energy. Although the thermal decomposition mechanism of TKX-50 has been reported, the specific compositional changes of its gas products under different heating conditions remain unknown, hindering a comprehensive understanding of the mechanism from the perspective of gas products. Herein, the gas products of TKX-50 and HMX in thermal decomposition and thermal explosion are investigated and compared. It was found that more TKX-50 is converted to ABTOX for further decomposition when the heating rate increases. ABTOX can decompose to C2N2, which is prone to polymerization, generating a solid residue under high temperature and pressure. Although polymerized C2N2 decomposes and burns during the explosion, it delays the time of TKX-50 reaching its maximum amount of outgassing, thereby affecting its specific kinetic energy. Furthermore, in the thermal explosion, compared with HMX, TKX-50 generates less H2 and CO. Since the combustion heat of hydrogen is much higher than that of carbon, the more hydrogen generated, the higher the detonation heat obtained. Therefore, TKX-50 has a lower detonation heat, which also affects its specific kinetic energy.

No abstract available

No abstract available

No abstract available

No abstract available

To conduct a comprehensive analysis of the weak interactions among the fragments in the dihydroxylammonium 5,5′‐bistetrazole‐1,1′‐diolate (TKX‐50) molecular crystal, a bis‐tetrazolium fragment was chosen as the central fragment interest, analyzing the Hirshfeld surfaces, fingerprint plots, dispersion density and the independent gradient model based on Hirshfeld partition (IGMH) between the atoms in this fragment and other surrounding fragment's atoms based on the theory calculation level of PBE/DZVP‐MOLOPT‐GTH, summing up the interactional type and strength and comparing them with that in the gaseous TKX‐50 molecules. The results revealed that the range of weak interaction within the crystal was narrower than that in the molecules, and the characteristic π⋯π stacking originated from the interactions of four atom pairs: two pairs of C⋯N and two pairs of N⋯N between two face‐to‐face tetrazole rings. These characteristics principally arise frodm two factors: (1) The final balance is achieved when more reciprocal interactions are exerted on the atoms of various fragments during the stacking process, from TKX‐50 molecules to crystals. (2) The attraction of electrons, proposed by the stronger electronegativity of the O atoms bonded to the bis‐tetrazolium fragments, results in the deviation of the electron density of the tetrazole rings to the side of O and eventually forms the π⋯π stacking, as demonstrated in this study.

No abstract available

No abstract available

Vacancy defects are commonly present in crystals of energetic materials, and significantly influence the structural stability and decomposition mechanisms. However, there is a lack of profound understanding regarding the introduction of vacancy defects in energetic ionic salt, dihydroxylammonium 5,5'-bitetrazole-1,1'-dioxide (TKX-50). Due to the 1 : 2 ratio of anions to cations, TKX-50 possesses a more complex distribution of vacancy defects compared to traditional energetic materials. Based on the density functional theory method, the relatively favorable thermodynamic formation of vacancy defect distributions was revealed. The noncovalent interactions within the system, as well as the planarity of the anions, were investigated to understand the structural stability of TKX-50. Through ab initio molecular dynamics simulations, we discovered that vacancy defects can expedite the proton transfer during the initial decomposition stage of TKX-50 and affect the pathways of proton transfer. In the subsequent decomposition process, introduction of vacancy defects in the TKX-50 crystal leads to an earlier onset of ring-opening reactions and accelerates the appearance of decomposition products. The findings have the potential to provide insights into modeling vacancy defects in energetic ionic salts and reveal the impact of such defects on the structural stability and decomposition mechanisms of these materials.

No abstract available

The cylinder expansion (CYLEX) test is commonly used to describe the adiabatic expansion of the detonation products and calibrate the equation of state (EOS) of detonation products. A CYLEX test method analogous to the T-20 (pre-set position and record the time of arrival) methodology was developed utilizing a set of probes with radial displacement difference and a high-speed pulse timer to record the radial expansion displacement of the cylinder wall. Two CYLEX tests for Dihydroxylammonium 5,5’-bitetrazole-1,1’-dioxide (TKX-50)-based explosives and two for 2, 4, 6-trinitrotoluene (TNT) were conducted using the CYLEX test method developed, and further Jones-Wilkins-Lee (JWL) EOS parameters of detonation products were determined using the BP neural network and genetic algorithm (BP-GA) program. Besides, the JWL EOS parameters obtained were numerically validated by performing the simulations of the CYLEX test, where the simulation results were consistent with the experimental data.

Abstract Four energetic binders, polyglycidyl nitrate (PGN), poly(3-nitratomethyl-3-methyloxetane) (PNIMMO), poly(bis(azidomethyl)oxetane) (PBAMO), and glycidyl azide polymer (GAP) were, respectively, mixed with dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50), forming TKX-50-based polymer bonded explosives (PBXs). Interfacial forces (binding energies) under different temperatures, mechanical properties (tensile modulus, bulk modulus, shear modulus, and Poisson’s ratio), and moldability of TKX-50-based PBXs were investigated by employing molecular dynamics simulation, the energy characteristics of TKX-50-based PBXs were calculated by Chapman–Jouguet (C–J) detonated theory. Results show that temperature has little effect on the binding energies, but the binding energies between every energetic binder and each surface of TKX-50 are different and the order of combined ability between four energetic binders and TKX-50 decrease as follows: PNIMMO > PBAMO > PGN > GAP. Compared with TKX-50, the addition of four energetic binders makes the rigidity of TKX-50-based PBXs decrease and the plasticity improve, the plastic ability rank is in the order of PGN > PNIMMO > PBAMO > GAP. In addition, the moldability of TKX-50-based PBXs is obviously improved, the increasing order is PGN > PNIMMO > PBAMO > GAP. Finally, the detonation performances indicate that compared with common binder, the addition of the energetic binder makes TKX-50-based PBXs have higher energy under the same condition.

This study presents a safe and scalable synthesis of dihydroxylammonium 5,5'‐bistetrazole‐1,1'‐diolate (TKX‐50), a high‐performance explosive with superior detonation velocity and reduced sensitivity. Traditional methods face challenges such as harsh conditions, corrosive reagents, and sensitivity of intermediates. We introduce a novel approach that replaces sensitive intermediates, eliminates corrosive HCl gas, and optimizes reaction conditions. Using a single equivalent of HCl in solution at lower temperatures, we achieve high yields of TKX‐50 under milder conditions. This method improves efficiency, scalability, and safety, facilitating broader use of TKX‐50 as a next‐generation explosive.

Polymer-bonded explosives (PBX), as a classical representative of energetic composite materials, have poor mechanical properties due to weak interface interaction, which limits their wide application. Inspired by the strong adhesion of mussels, coating polydopamine (PDA) on the surface of energetic materials is considered an effective method to enhance the interaction. In this study, the self-polymerization of dopamine was accelerated by the addition of potassium permanganate, which was successfully coated on the surface of dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50), a high-energy and insensitive energetic material. After PDA coating, TKX-50 had excellent thermal stability and mechanical properties. The spontaneous decomposition temperature and thermal explosion critical temperature of TKX-50 after PDA coating increased from 204.300 and 217.604 °C to 210.700 and 223.839 °C, respectively, and the compressive strength increased from 6.38 to 7.65 MPa. This novel method improves the thermal stability and mechanical properties of energetic materials to ensure their large-scale industrial production and application.

To further comprehensively study the intramolecular weak interaction of the gaseous TKX‐50 molecule, the two conformations of the TKX‐50 molecule were analyzed via the Independent Gradient Model based on the Hirshfeld Partition (IGMH) method based on the B3LYP/6‐311 g (d,p) level for geometry optimization and for single point energy. The conclusions manifest that the weak interactions between these fragments are mainly composed of hydrogen bonds and van der Waals interactions. From the strength of inter‐fragment interactions formed by contributing atomic pairs and their percentage contributions, these H bonds, together with dispersion‐dominated weak interactions provided by non‐direct facing atomic pairs near these H bonds, dominate the inter‐fragment interaction resulting in the stability of the molecular structure. Meanwhile, the weak interactions enclosed by end‐atoms of two fragments not only include the contributions provided by inter‐fragment atomic pairs of two fragments but also include the contributions provided by intra‐fragment atomic pairs of fragment 1. For conformation II, due to the H transfer between fragments, a pair of symmetric H bonds at the corresponding regions are extremely strong to reach the level of covalent bond while the two groups −OH at the other end become looser, resulting in conformation II own lower energy. Differences in inter‐fragment interactions between two conformations were essentially brought by the stronger electron‐withdrawing ability of atom O than that of atom N.

No abstract available

No abstract available

Different types of TKX-50/PBA-I composite materials were prepared by the solution-water suspension method, and the influence of the content of anionic groups on the coating effect was explored by SEM, FT-IR, XPS and TGA. The results showed that PBA-I were successfully coated on the crystal surface of TKX-50, and the content of anionic group -COOH increased, which was conducive to the coating effect of the bonding agent on TKX-50. Among the different anionic bonding agents, PBA-I-3 had the best coating effect.

In response to the growing concerns about the unauthorized use of advanced secondary explosives such as TKX-50 against non-combatant targets, there is an urgent need for effective detection methods or techniques to ensure efficient security screening, homeland security, and public safety. Herein, a new polymeric receptor (IV) derived from functionalized tetraphenylethylene moiety (TPE) and 1,3,5-tris(4-aminophenyl)benzene (TAPB)  moieties for the efficient detection of TKX-50 through a 'switch ON' luminescence response upon specific binding to the explosive, is reported. The observed 'luminescence ON' response is rationalized based on a charge transfer complex formation between TKX-50 and the polymeric receptor IV (Ka = 1.7 × 104 m-1). This is validated by the steady and excited-state luminescence studies, along with detailed computational studies. The authors' presumptions are further validated with adequate control studies using an appropriate monomeric derivative (III) of TPE. Moreover, this 'luminescence ON' response can be integrated into a smart and user-friendly Internet of Things (IoT)-based prototype device. This device can effectively convert optical responses into digital output to develop an optical device for real-time detection of TKX-50 in solution. This lightweight, portable device is ideally suited for remote surveillance and monitoring of TKX-50; such examples are rare in contemporary literature.

No abstract available

No abstract available

ABSTRACT Nanostructured energetic materials have attracted considerable research interests during the past decades because of their improved performances in thermal decomposition and combustion. In this work, a porous nanosheet structure of dihydroxylammonium 5, 5′-bistetrazole-1, 1′-diolate (TKX-50) has been fabricated by a facile ice templating strategy, which is based on the self-assembly of TKX-50 during rapid recrystallization. Thermal decomposition properties were determined by differential scanning calorimetry/thermogravimetry (DSC/TG) and TG-FTIR analyses. The laser-ignited and constant-volume combustions and mechanical sensitivity were conducted. As-prepared TKX-50 mainly presents porous nanosheets (NS-TKX-50) assembled by the secondary nanoparticles. NS-TKX-50 is typical of mesoporous materials with high specific surface area and pore volume. Compared with raw material, NS-TKX-50 exhibits lower thermal decomposition peak temperature and higher active energy. In thermal decomposition process, a great deal of gaseous products have been generated in a very narrow temperature range. These thermal decomposition features suggest a quick energy-release rate and high energy output. Contrary to incomplete combustion of raw material, NS-TKX-50 shows high-efficiency and self-sustaining laser-ignited combustion feature with a drastically decreased ignition threshold. And its pressurization rate and peak pressure are remarkably increased. Sensitivity results confirmed the visibly reduced impact and friction sensitivity of NS-TKX-50.

Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) is a newly synthesized explosive with excellent comprehensive properties. Cyclotetramethylenetetranitramine (HMX) is currently one of the highest energy explosives used around the world. TKX-50/HMX cocrystal can improve the defects of TKX-50 and HMX and vastly expand their application scope. TKX-50 and HMX supercell structures and TKX-50/HMX cocrystal structures were established based on their crystal cell parameters and the formation mechanism of the cocrystals, respectively. The binding energy, radial distribution function (RDF), X-ray powder diffraction (XRD), cohesive energy density (CED) and mechanical properties were simulated based on the equilibrium structures of models via molecular dynamics (MD) simulations. The calculated results indicate that the TKX-50/HMX cocrystal forms as a new structure under the intermolecular forces, and the cocrystal structures of TKX-50 substituted by HMX on its slow-growing facets are more stable. Moreover, the cocrystal structure has greatly improved the high sensitivity defect of HMX and the mechanical properties of TKX-50 and HMX; thus the cocrystal will be more likely to be used widely in the energetic materials field.

The influence of twinned crystals on the performance of TKX-50 is investigated using normal TKX-50 and twinned TKX-50 supercells. ReaxFF-lg reactive molecular dynamics simulations are performed to study thermal decomposition and oxidation.

TKX‐50‐based explosives, owing to their high detonation performance and low sensitivity, are considered promising candidates for future warhead main charges. Existing studies have primarily focused on synthesis optimization, composite material design, thermal decomposition mechanisms, and basic detonation parameters, whereas investigations into the static blast pressure field of TKX‐50‐based explosives remain limited. In this work, a numerical simulation model of the static blast shock wave pressure field of TKX‐50‐based explosives was established using LS‐DYNA. The simulated overpressure results show good agreement with experimental data, with deviations within 6%, demonstrating the reliability of the proposed model. On this basis, the effects of key operating parameters—including scaled distance, burst height, length‐to‐diameter ratio, and initiation mode—on the shock wave pressure field of TKX‐50‐based explosives were systematically investigated. Furthermore, LS‐OPT was coupled with LS‐DYNA to conduct optimization analysis, through which a numerical prediction of the optimal blast height was determined within a selected range of parameters.

Dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) is a promising candidate to replace traditional explosives, 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) and 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), used in insensitive munitions, which is currently being explored to achieve shock insensitive melt cast formulations. Safety and energetic properties of melt cast explosive formulations help in implementing applications in the future. In the present study, TKX-50 based melt cast formulations are prepared with 2,4,6-trinitrotoluene (TNT) as a dispersant. Furthermore, the safety assessment and energy performance are studied along with HMX based melt cast formulations for comparison. In order to gain insight into the coating mechanism, the interaction energies calculations were performed at the B3LYP/6-311G** level. The results revealed that stronger attractive forces exist in TKX-50–TKX-50 than in HMX–HMX pairs and similarly in TKX-50–TNT than in HMX–TNT, which have good agreement with the coating conditions. This comparative study reveals that the safe and energy performance of TKX-50 based formulations is superior to HMX based formulations.

No abstract available

No abstract available

Two complexes of dihydroxylammonium 5,5´-bistetrazole-1,1´-diolate (TKX-50) were employed to evaluate the aromaticity of their tetrazole rings via deep analysis such as the electronic structure, the ZZ component of the natural chemical shielding tensor (NICSZZ) and component orbitals, localized orbital locator purely contributed by σ-orbitals (LOL-σ) and localized orbital locator purely contributed by π-orbitals (LOL-π), the anisotropy of the induced current density(AICD) and the ZZ component of iso-chemical shielding surface(ICSSZZ)of these tetrazole rings thereof. The conclusion shows: that all tetrazole rings and bi-tetrazole rings in complexes have strong σ and a comparable strength π double aromaticity; all these magnetic shields almost symmetrically increase from the central axis to the tetrazole ring atoms; tetrazole rings in complex II show a little stronger dual aromaticity than that in complex I mainly due to the different orientation of the fragment 2 encompassing two hydroxylamine groups resulting in different effects on the contributions of σ orbitals and π orbitals to total aromaticity of tetrazole rings thereof; the difference in aromaticity is fundamentally caused by the atoms O with stronger electron-withdrawing than atom N in fragment 2 interact with bi-tetrazole ring through O in complex I but through N in complex II.

No abstract available

ABSTRACT Dihydroxylammonium5,5′-bistetrazole-1,1′-diolate (TKX-50) is considered as one of the new ionic energetic materials. In this study, we employed density functional theory (DFT) method to calculate the reaction path of TKX-50 and search its optimized configurations of reactants, reactant complexes (RCs), transition states (TSs), product complexes (PCs), and products. We proposed 10 simple reactions in the reaction path, and determined their transition states. Among these TSs, six of them have lower energies than those of reactants. The equilibrium constants, which indicate the limitation of reactions, were computed from the difference of Gibbs free energy with temperature change. Based on the proposed reaction path, the reaction mechanism of TKX-50 was provided.

No abstract available

No abstract available

No abstract available

No abstract available

ABSTRACT TKX-50, as a representative of a new nitrogen-rich energetic compound, has attracted extensive interests due to its high energy and low sensitivity properties. As an important energetic material, combustible agent has great influence on improving the energy level of explosives and propellants. Boron powder has become the most potential combustible agent in energetic fields because of its unique performances. In this work, nano-boron-based microspheres containing TKX-50 are directly fabricated by electrospray deposition. The prepared microspheres showed high monodispersity with particle size ranging from ~1–3 μm. Thermal behavior results show that the mass gain of the electrostatically sprayed sample is 163.3%, which is much higher than that of pure boron and physically mixed samples. Combustion behavior tests show that electrosprayed microspheres exhibit outstanding performance in comparison to physical mixed sample, the peak pressure improved by 85%, the burning time decreased by 21% and the pressurization rate improved by 136%. These excellent properties are probably related to their uniform microstructure. Therefore, electrospray preparation of microspheres with controllable structure has a good application prospect in energetic materials.

A computational study of the detonation characteristics of several explosive formulationsbased on the energetic material TKX-50 has been carried out. Materials such as paraffin, HTPB, GAP, AMMO and BAMO were considered as fillers or binders. The influence of such fillers (with a volumetric content of up to 50 %) on the detonation characteristics of the composite energetic materials was investigated. The influence of porosity on the detonation characteristics of composite explosive formulations with a binder mass content of 5 and 10% was determined. An analysis of the (limited) experimental data for the detonation velocity of explosive formulations based on TKX-50 was undertaken. The experimentally determined detonation velocities of three explosive formulations with inert and energetic binders which have been previously published in the literature were considered and analysed. Good agreement was found between the calculated and experimental results for the detonation velocity. A computational study of the explosion impact of charges of TKX-50, as well as of explosive formulations based on it containing the above-mentioned binders, on copper plates with a thickness of 1 mm and on layers with a thickness of 50 mm was carried out. The mass content of binders in the explosive formulations was 5 %. The charges were 50 mm thick and consisted of compact or porous materials with a porosity of 2 %. The Explo5 and Ansys Autodyn programs were used to perform thermochemical, thermodynamic and gas-dynamic calculations.

No abstract available

ABSTRACT Design and fabrication of micro- and nanostructures for energetic materials have attracted more attention recently to improve safety properties and enhance detonation performance. Exploring and developing dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) with unique microstructures, an emerging high-energy-density material with superior comprehensive properties, is of great significance for the potential applications. In this work, we reported that three-dimensional (3D) TKX-50 network-like nanostructures were designed and fabricated successfully via the liquid nitrogen-assisted spray freeze-drying method. Characterization results suggested 3D TKX-50 network-like nanostructures were constructed by self-assembly of small nanoparticles. Furthermore, a nucleation-and-growth self-assembly formation mechanism of the network-like nanostructures depended on the different concentrations of the aqueous solution of TKX-50 was proposed in detail based on the experimental results. More interestingly, thermal analysis results demonstrated these novel 3D TKX-50 network-like nanostructures are much easier to be activated and have a lower decomposition temperature than the raw material, due to decrease in particle sizes, and the impact sensitivity of 3D TKX-50 network-like nanostructures become more sensitive than that of raw TKX-50. Their friction sensitivity of as-prepared samples is similar to the raw materials. Therefore, this work could provide a new prospect for fabrication and application of TKX-50 nanostructures.

In order to decrease the sensitivity and broaden the application of pentaerythritol tetranitrate (PETN), a novel energetic co-crystal composed of PETN and dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) with high energy and low sensitivity was successfully prepared through the solvent/non-solvent method. The morphology and structure of the as-prepared co-crystal were characterized by scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectrometry (XPS), fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and high performance liquid chromatography (HPLC). The thermal decomposition properties were also analyzed by simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC). The safety performance was judged by mechanical sensitivity tests. The SEM results revealed that the prepared new material was homogeneous with a mean granularity of 1 μm and the morphology was distinct from raw PETN and TKX-50. The XRD analysis indicated that a new crystalline formation appeared in the co-crystal which was quite different from the raw materials and their mixture. The XPS analysis showed peak shifts of C, N, O elements in the co-crystal. The FTIR spectra and Raman spectra suggested that hydrogen bond interactions existed between PETN and TKX-50 molecules. The molar ratio of PETN and TKX-50 was 1 : 1 determined by HPLC. There were two thermal decomposition peaks (194.1 °C and 261.3 °C) for the co-crystal at 20 °C min−1, while the raw materials and mixture had only one. Besides, the activation energy of the co-crystal increased compared to the raw materials, indicating better thermal stability of the co-crystal. The impact sensitivity and friction sensitivity of the PETN/TKX-50 co-crystal were reduced compared to raw PETN, and were even better than for 1,3,5-trimethylene trinitramine (RDX). The results showed a prospective application of the prepared PETN/TKX-50 co-crystal in the future.