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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.

3-Nitro-1,2,4-triazole-5-one (NTO) has received wide attention and has applications owing to its excellent detonation performance and low sensitivity. A new crystal form of NTO was prepared via the solvent evaporation method and named γ-NTO. Its crystal properties were studied through single-crystal X-ray diffraction, and the results indicated that the unit cell of γ-NTO belongs to the monoclinic space group Pc, with eight molecules in the single unit cell. The density of this crystal is calculated to be 1.907 g cm−3, which is higher than that of β-NTO and similar to that of α-NTO. The crystal morphology was calculated to be a polygonal shape with a symmetrical growth pattern using the reactive force field. Based on the analysis of reactive molecular dynamics, the thermal decomposition mechanism of different crystal forms of NTO was elucidated, and the results showed that γ-NTO demonstrates higher gas production, providing a successful way to enhance detonation performance. The results of IR and differential thermal analysis (DTA) support the above conclusions. [ABSTRACT FROM AUTHOR]

As a new structural motif, an interesting 3D energetic metal – framework of silver ions and 3,4-diaminofurazan, [Ag+(daf)NO3−]n, is successfully synthesized and the structure is determined by single-crystal X-ray diffraction. The effects of hydrogen bond, coordination bond, adsorption and filling interactions make this compound have a high density (2.694 g·cm−3 at 293 K). The calculated detonation velocity and the sensitivities are all comparable with trinitrotoluene (TNT). The onset decomposition temperature is equal to hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), state-of-the-art explosive. This framework provides a potential superiority of E-MOFs for energetic materials. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are a new class of functional solids featuring several fantastic structural characteristics, including a great diversity of building units and cross-linking patterns, precise integration of building blocks, and adjustable topology of porous architecture. In addition to the above features, some COF samples are constructed with high-density conjugated fragments, which have unique potential advantages in fluorescence imaging, and thus may have great potential applications in bioimaging. Herein, this article summarizes the recent progress in the design and preparation of fluorescent covalent organic frameworks. We investigate the systemic correlation between the structural qualities of COF networks and biological sensors. Finally, the significant advantages, major challenges, and future opportunities of fluorescent covalent organic frameworks are discussed for the development of next-generation porous materials for sensing applications. [ABSTRACT FROM AUTHOR]

In this paper, novel UiO‐66‐AO‐based adsorption‐filtration hybrid membranes (UAMs) are prepared via an irradiation‐mediated growth strategy to simultaneously improve water flux and accelerate uranium extraction from water resources. The UAM shows an equilibrium adsorption that is four times faster than UiO‐66‐AO powder and an adsorption capacity that is over two times higher. UAM also achieves a record synergy of high flux and high uranium removal ratio from simulated seawater (1358.8 L m−2 h−1, 84.5%) by one‐time filtration under ambient temperature and pressure (the adsorption is 1.83 mg g−1 in 90 min). The excellent uranium extraction performance is attributed to the unique UAM structure, in which water flows through the channels of thin metal‐organic framework (MOF) film without blocking by substrate leading to the high flux during filtration, and the full contact of uranium with abundant exposed active sites promotes the adsorption. This work will be conducive to overcoming the bottleneck problems of uranium extraction from water resources. [ABSTRACT FROM AUTHOR]

Chitosan microspheres(HTCC) were prepared by hydrothermal method,and Amino-modified chitosan adsorbent (AHTCC) was prepared by epoxidization and amination method to adsorb low concentration uranium in wastewater. The structure, composition and thermal stability of AHTCC were characterized by infrared spectrometer, elemental analyzer and thermogravimetric analyzer, and the adsorption and desorption properties of AHTCC for uranium were investigated. The results show that AHTCC has a good adsorption effect on uranium in solution at pH=5~8. Under the condition of equilibrium mass concentration of uranium adsorption of 120 mg/L,the adsorption capacity reaches the 151. 6 mg/g. Its adsorption rate is faster in the initial 60 min and reaches equilibrium at 180 min. Using 80 g/L Na2CO3+20 g/L NaHCO3 as the desorption agent, the desorption rate of uranium is 97. 5%. For real uranium containing wastewater with high concentration of impurities, the removal rate of uranium can reach 95. 6% after single adsorption by AHTCC. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) coatings display several advantages such as easy construction, adjustability, and excellent mechanical properties, and therefore have potential applications in the coating of rocket engines and warheads. However, mechanical strength, high ductility and thermal stability are often difficult properties to combine, which has become a key limitation in efforts toward developing PU coatings for these applications. In this paper, a fast‐curing PU film was developed by reacting between polytetrahydrofuran and diphenylmethane 4,4'‐diisocyanate. The mechanical strengthening effect of SiC nanoparticles on the film was studied and compared with other common fillers, including TiO2, XFM13. The results revealed that SiC nanoparticles substantially increased the mechanical properties in PU coating, increasing the material's tensile strength and elongation at break to 34.14 MPa and 434% respectively. In addition, the inclusion of SiC nanoparticles generally improved the thermal stability and low temperature resistance of PU film. The results generated in this research has established a foundation for the application of PU materials in fields requiring high performance properties, such as rocket engines coatings and warhead manufacture. [ABSTRACT FROM AUTHOR]

A low density resin was prepared by thixotropic suspension polymerization using chloromethyl styrene as monomer and high strength low density vacuum glass microspheres (HMG) as filler, and it was used to adsorb uranium from pulp. The results show that using sodium dodecyl sulfate as surfactant and bentonite as thixotropin can reduce the surface tension of continuous phase water, and the density of the prepared resin is low, about 0.87 g/mL. Under the conditions of alkaline pulp of 200 mL, uranium mass concentration of 500 mg/L, low density resin dosage of 1 g, CO32- mass concentration of 17. 5 g/L, HCO3- mass concentration of 6.3 g/L,pH = 10 and static adsorption of uranium at room temperature for 16 h, the equilibrium Is reached after three consecutive adsorption times and the saturated adsorption capacity is 51.8 mg/g. The adsorption process conforms to the quasi-second-order kinetic model and Langmuir Isothermal adsorption model. After 10 times of continuous countercurrent adsorption, the resin adsorption capacity can remain at about 48.2 mg/g, stable performance, no damage on the surface, the floating rate of resin Is close to 100%. [ABSTRACT FROM AUTHOR]

C6H5N11O6, monoclinic, P21/n (no. 14), a = 13.463(5) Å, b = 6.526(2) Å, c = 14.068(5) Å, β = 95.961(5)°, V = 1229.3(7) Å3, Z = 4, Rgt(F) = 0.0417, wRref(F2) = 0.1067, T = 153 K.

C6H6N12O12 · 0.33 H2O, orthorhombic, Pbca (no. 61), a = 9.5152(7) Å, b = 13.2551(11) Å, c = 23.6736(18) Å, V = 2985.8(7) Å3, Z = 4, Rgt(F) = 0.0727, wRref(F2) = 0.1268, T = 293(2) K.