Qiangqiang Liu

Nitrogen-Rich Energetic Metal-Organic Framework: Synthesis, Structure, Properties, and Thermal Behaviors of Pb(II) Complex Based on N,N-Bis(1H-tetrazole-5-yl)-Amine

The focus of energetic materials is on searching for a high-energy, high-density, insensitive material. Previous investigations have shown that 3D energetic metal–organic frameworks (E-MOFs) have great potential and advantages in this field. A nitrogen-rich E-MOF, Pb(bta)·2H2O [N% = 31.98%, H2bta = N,N-Bis(1H-tetrazole-5-yl)-amine], was prepared through a one-step hydrothermal reaction in this study. Its crystal structure was determined through single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, and elemental analysis. The complex has high heat denotation (16.142 kJ·cm−3), high density (3.250 g·cm−3), and good thermostability (Tdec = 614.9 K, 5 K·min−1). The detonation pressure and velocity obtained through theoretical calculations were 43.47 GPa and 8.963 km·s−1, respectively. The sensitivity test showed that the complex is an impact-insensitive material (IS > 40 J). The thermal decomposition process and kinetic parameters of the complex were also investigated through thermogravimetry and differential scanning calorimetry. Non-isothermal kinetic parameters were calculated through the methods of Kissinger and Ozawa-Doyle. Results highlighted the nitrogen-rich MOF as a potential energetic material.

Nitrogen-rich energetic salts of 1H,1′H-5,5′-bistetrazole-1,1′-diolate: synthesis, characterization, and thermal behaviors

A series of nitrogen-rich heterocyclic 1H,1′H-5,5′-bistetrazole-1,1′-diolate salts, namely, 1,2,4-triazolium (2), 3-amino-1,2,4-triazolium (3), 4-amino-1,2,4-triazolium (4), 3,5-diamino-1,2,4-triazolium (5), 2-methylimidazolium (6), imidazolium (7), pyrazolium (8), 3-amino-5-hydroxypyrazolium (9), dicyandiamidine (10), and 2,4-diamino-6-methyl-1,3,5-triazin (11), was synthesized with cations. These energetic salts were fully characterized through FT-IR, 1H NMR, 13C NMR, and elemental analysis. The structures of 2, 3·7H2O, 6·2H2O, 8, and 10·4H2O were further confirmed through single crystal X-ray diffraction. Their thermal stabilities were investigated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results indicated that all of the salts possess excellent thermal stabilities with decomposition temperatures ranging from 225.7 °C to 314.0 °C. On the basis of the Kamlet–Jacobs formula, we carefully calculated their detonation velocities and detonation pressures. All of the salts, except 11, exhibit promising detonation performances with a detonation pressure of 20.23–28.69 GPa and a detonation velocity of 7050–8218 m s−1. These values are much higher than those of TNT. The impact sensitivities of the compounds were determined via a Fall hammer test. All of the compounds show excellent impact sensitivities of >50 J, and this finding is higher than that of TATB (50 J). Therefore, these ionic salts with excellent energetic properties could be applied as new energetic materials.

Synthesis, Characterization, and Thermal Decomposition of a New Energetic Salt 3-Amino-1,2,4-Triazole Dinitramide

ABSTRACT A new energetic salt, 3-amino-1,2,4-triazole dinitramide (ATADN), was synthesized through the combination of 3-amino-1,2,4-triazole cation and oxygen-rich dinitramide anion. The structure of ATADN was confirmed by single-crystal X-ray diffraction, elemental analysis, Fourier transform infrared spectroscopy, ultraviolet–visible spectrometry, and nuclear magnetic resonance spectroscopy. The thermal stability of ATADN was studied using differential scanning calorimetry, thermogravimetric analysis (TG), and TG tandem infrared spectrum. The thermal decomposition kinetics parameter was also calculated using the differential thermal analysis data based on Kissinger’s method. Results indicated that ATADN exhibited resistance to thermal decompositions of up to 439 K, and a corresponding activation energy of Ea = 281.9 kJ·mol−1. Moreover, its mechanical sensitivity and detonation properties were evaluated, which showed promising results for its potential application as a highly explosive compound.

Synthesis and characterization of [60]fullerene-poly(3-azidomethyl-3-methyl oxetane) and its thermal decomposition

A new functionalized fullerene derivative, [60]fullerene-poly(3-azidomethyl-3-methyl oxetane) (C60-PAMMO), was synthesized for the first time using a modified Bingel reaction with [60]fullerene (C60) and bromomalonic acid poly(3-azidomethyl-3-methyl oxetane) ester (BM-PAMMO). The product was characterized by Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis), and nuclear magnetic resonance (NMR) spectroscopy analyses. The results confirmed the successful preparation of C60-PAMMO. Moreover, the thermal decomposition of C60-PAMMO was analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis coupled with infrared spectroscopy (TG-IR), and in situ FTIR spectroscopy. The decomposition of C60-PAMMO showed a three-step thermal process. The first step at approximately 150 °C was related to the cycloaddition of the azido groups (–N3) with [60]fullerene. The second step was ascribed to the decomposition of the remaining PAMMO main chain at approximately 320 °C. The final step was attributed to the burning decomposition of amorphous carbon, the main chain, N-heterocyclic components and the carbon cage around 510 °C.

Synthesis, characterization, and thermal analysis of a new energetic salt based on 1ʹ-hydroxy-1H,1ʹH-5,5ʹ-bitetrazol-1-olate

ABSTRACT 4-Amino-1,2,4-triazolium 1ʹ-hydroxy-1H,1ʹH-5,5ʹ-bitetrazol-1-olate (ATHBTO) was synthesized by reacting 4-amino-1,2,4-triazole (AT) and 1H,1′H-5,5′-bistetrazole-1,1′-diolate dihydrate (H2BTO·2H2O). Its crystal structure was characterized through single-crystal X-ray diffraction. Meanwhile, FTIR, 1H NMR, 13C NMR, and elemental analysis were also introduced to analyze its composition. The thermal stability was investigated by differential scanning calorimetry, thermogravimetric analysis, and thermogravimetric tandem infrared spectrum. Results indicated that ATHBTO exhibited excellent resistance to thermal decompositions reaching 511.4 K and had a 64.6% mass loss between 475.7 and 552.3 K. The kinetics parameters were calculated by Kissinger’s method and Ozawa–Doyle’s method. Moreover, according to the Kamlet–Jacobs formula, the calculated detonation velocity and detonation pressure of ATHBTO attained 8218 m/s and 28.69 GPa, respectively.

Preparation and characterization of insensitive HMX/rGO/G composites via in situ reduction of graphene oxide

Composites of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane/reduced graphene oxide/graphite (HMX/rGO/G) were successfully prepared via an in situ chemical reduction coating method. The morphology, composition and thermal decomposition characteristic of the composites were analyzed by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy and differential thermal analysis (DTA). rGO together with G exhibited a better desensitizing effect than fullerene and carbon nanotubes. When 1.0 wt% GO and 1.0 wt% G were added as desensitizing materials, the impact sensitivity of raw HMX decreased from 100% to 8% and the friction sensitivity decreased from 100% to 0% after in situ chemical reduction coating. Meanwhile, DTA results indicated that rGO and G were compatible with HMX. These combined properties suggest that rGO sheets along with graphite can be utilized as co-desensitizers in HMX explosives.