Metal organic frameworks (MOFs) are considered as a group of compounds, either metal ions or clusters, harmonized with organic ligands to form one or some dimensional structures. In addition to resilient bonds between inorganic and organic units, reticular synthesis creates MOFs, accurate selection of constituents of which can produce high thermal and chemical stability and crystals of ultrahigh porosity. Other solids have not shown the same accuracy normally used in chemical modification and even the capability of increasing their metrics with no modification of the underlying topology. With shape of building units and chemical compositions multiplying based on specific structures, MOFs might result in compounds that propose a synergistic mixture of features. This study presents up to date advances in both synthesis methods of MOFs and structural characteristics. Furthermore, the use of MOFs in different fields such as the removal of absorption and separation of toxic substances from gas and liquid, catalysts, a variety of sensors, storage of clean energies and environmental applications, medical and biological applications, and optoelectronic equipment is included.

A review on metal-organic frameworks: Synthesis and applications

Energetic materials, including explosives, pyrotechnics, and propellants, are widely used in mining, demolition, automobile airbags, fireworks, ordnance, and space technology. Nanoenergetic materials (nEMs) have a high reaction rate and high energy density, which are both adjustable to a large extent. Structural control over nEMs to achieve improved performance and multifunctionality leads to a fascinating research area, namely, nanostructured energetic materials. Among them, core-shell structured nEMs have gained considerable attention due to their improved material properties and combined multiple functionalities. Various nEMs with core-shell structures have been developed through diverse synthesis routes, among which core-shell structured nEMs associated with explosives and metastable intermolecular composites (MICs) are extensively studied due to their good tunability and wide applications, as well as excellent energetic (e.g., enhanced heat release and combustion) and/or mechanical properties. Herein, the preparation methods and fundamental properties of the abovementioned kinds of core-shell structured nEMs are summarized and the reasons behind the satisfactory performance clarified, based on which suggestions regarding possible future research directions are proposed.

Core–Shell Structured Nanoenergetic Materials: Preparation and Fundamental Properties

Copper and calcium-based metal organic framework (MOF) catalyst for biodiesel production from waste cooking oil: A process optimization study

Efficient thermal management is becoming a global challenge with the rapid development of modern electronics. Therefore, conventional thermally conductive nanocomposites exhibit severe interfacial thermal resistance (ITR) generated at the interfaces of loaded thermally conductive components. Here, we design and synthesize a low-ITR carbon nanotube (CNT)/MoS 2 /graphene heterostructure in which the novel properties of highly thermally conductive CNTs, MoS 2 , and graphene are synergistically integrated into the final nanocomposite. During the hydrothermal reaction process, MoS 2 and graphene are grown and wrapped on CNTs which ensure better interfacial contact. The CNTs act as a structural skeleton and heat transfer channel for effective heat collection from the large-surface-area MoS 2 and graphene nanosheets. MoS 2 which has good wetting properties further reduces the ITR between the heterostructure filler and polymer matrix; thus, a high−efficiency heat transfer channel of epoxy−graphene−MoS 2 −CNT is prepared. The synthesized CNT/MoS 2 /graphene−epoxy nanocomposite shows a much lower ITR of 8.3 × 10 6  K W −1 than a CNT-epoxy nanocomposite (3.98 × 10 7  K W −1 ) and a CNT/MoS 2 −epoxy nanocomposite (1.9 × 10 7  K W −1 ). Consequently, the thermal conductivity is improved from 2.0 W m −1  k −1 to 4.6 W m −1  k −1 , which is 2300% of that of the pure epoxy resin. The factors affecting ITR and thermal conductive properties are analyzed. Our findings may contribute to the development of new types of high−performance thermal management materials.

Thermal conductivity enhancement of CNT/MoS2/graphene−epoxy nanocomposites based on structural synergistic effects and interpenetrating network

Mussel-inspired coating of energetic crystals: A compact core–shell structure with highly enhanced thermal stability

In this study, a novel Cu-MOF@Carbon nanomaterial composite was prepared to catalyze the thermal decomposition of ammonium perchlorate (AP). The structure was characterized by using scanning electron microscope (SEM), X-ray energy-dispersive spectrum (EDS), and X-ray diffraction (XRD); the specific surface area was estimated by Brunauer–Emmett–Teller (BET) method; and the pore volumes and pore size distributions were derived from the adsorption branches of isotherms using the Barrett–Joyner–Halenda (BJH) model. And the thermal decomposition behavior was investigated by using differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The results indicated that all products showed excellent catalytic activity. Among the samples investigated here, Cu-MOF@CNT-rGO exhibited the best catalytic activity, since the high-temperature decomposition peak of AP decreased to 313.8 °C, which is reduced nearly 100 °C than the raw material (409.7 °C). And this was attributed to the high thermal and electrical conductivities of carbon nanomaterials, and the large surface area of both Cu-MOF and carbon nanomaterials. This study provides a new choice to be used as the promising catalysts in modifying the burning performance of AP-based composite propellant.

Synergistic effects between Cu metal–organic framework (Cu-MOF) and carbon nanomaterials for the catalyzation of the thermal decomposition of ammonium perchlorate (AP)

Spray drying method was used to prepare cocrystals of hexanitrohexaazaisowurtzitane (CL-20) and cyclotetramethylene tetranitramine (HMX). Raw materials and cocrystals were characterized using scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, Raman spectroscopy, and Fourier transform infrared spectroscopy. Impact and friction sensitivity of cocrystals were tested and analyzed. Results show that, after preparation by spray drying method, microparticles were spherical in shape and 0.5ź5źµm in size. Particles formed aggregates of numerous tiny plate-like cocrystals, whereas CL-20/HMX cocrystals had thicknesses of below 100źnm. Cocrystals were formed by CźHźO bonding between źNO2 (CL-20) and źCH2ź (HMX). Nanococrystal explosives exhibited drop height of 47.3źcm, and friction demonstrated explosion probability of 64%. Compared with raw HMX, cocrystals displayed significantly reduced mechanical sensitivity.

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Nano-CL-20/HMX Cocrystal Explosive for Significantly Reduced Mechanical Sensitivity

Herein, we report a facile strategy to prepare a novel HMX-based microspheres by coating a layer of energetic binders on HMX. HMX-based microspheres were synthesized and compared by different dissolution methods by spray dying. The HMX-based composites were also prepared by a water-suspension method. The formation mechanism of the hollow structure and core–shell structure is proposed. The as-prepared HMX/NC/GAP microspheres synthesized by suspension spray drying were found to possess a solid core–shell structure, display a β-form, lower impact sensitivity and higher energy performance.

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Formation and properties of HMX-based microspheres via spray drying

To improve the safety performance of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) particles, the new carbon material graphene oxide (GO) and Viton were used to coat HMX via a solvent–slurry process. For comparison, the HMX/Viton/graphite (HMX/Viton/G) and HMX/Viton composites were also prepared by the same process. Atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC) were employed to characterize the morphology, composition, and thermal decomposition of samples. The impact sensitivity and shock wave sensitivity of HMX-based composites were also measured and analyzed. The results of SEM, XRD, and XPS indicate that the cladding layer of HMX-based composites is successfully constructed. HMX/Viton/GO composites exhibit better thermal stability compared to HMX and HMX/Viton. The results show that both impact and shock wave sensitivities of HMX/Viton/GO composites are much lower t...

Preparation and Properties of Surface-Coated HMX with Viton and Graphene Oxide

A one-step method which involves exfoliating graphite materials (GIMs) off into graphene materials (GEMs) in aqueous suspension of CL-20 and forming CL-20/graphene materials (CL-20/GEMs) composites by using ball milling is presented. The conversion of mixtures to composite form was monitored by scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The impact sensitivities of CL-20/GEM composites were contrastively investigated. It turned out that the energetic nanoscale composites based on CL-20 and GEMs comprising few layers were accomplished. The loading capacity of graphene (reduced graphene oxide, rGO) is significantly less than that of graphene oxide (GO) in CL-20/GEM composites. The formation mechanism was proposed. Via this approach, energetic nanoscale composites based on CL-20 and GO comprised few layers were accomplished. The resulted CL-20/GEM composites displayed spherical structure with nanoscale, e-form, equal thermal stabilities, and lower sensitivities.

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Baoyun Ye

Papers

Synergistic effects between Cu metal–organic framework (Cu-MOF) and carbon nanomaterials for the catalyzation of the thermal decomposition of ammonium perchlorate (AP)

Nano-CL-20/HMX Cocrystal Explosive for Significantly Reduced Mechanical Sensitivity

Formation and properties of HMX-based microspheres via spray drying

Preparation and Properties of Surface-Coated HMX with Viton and Graphene Oxide

One-Step Ball Milling Preparation of Nanoscale CL-20/Graphene Oxide for Significantly Reduced Particle Size and Sensitivity.