Constructing advanced pyrazole-based energetic materials via direct hydrazine substitution of a heterocyclic C–NH2 bond

On the occasion of his 60 th birthdayThe chemistry of energetic materials is a domain of research with ample facets stretching from pyrotechnics over propellants to high explosives.Each of these fields has plentiful subdomains with very unique features and most unfortunately, structure/property relationships which cannot be easily transferred from one field to another.It is this heterogeneity, which complicates coherent research in our field and has contributed to the common perception that propellants, high explosives, and most prominently, pyrotechnics, are arts and crafts rather than genuine parts of modern science.

Difluoromethylation and trifluoromethylation reagents derived from tetrafluoroethane β-sultone: Synthesis, reactivity and applications

The paper begins with a review of the literature on high pressure and shear properties of materials. This is an area in which further interest was recently stimulated by published Russian work on s...

Investigation of the Structural, Vibrational, Electronic, and optical properties of energetic Nitrogen-Rich azidotetrazolates XCN7 (X = N2H5, NH4, K, Cs)

This paper examines the influence of microstructure on the quasi–static failure of PBX 9501, a polymer–bonded explosive (PBX) manufactured for the Los Alamos National Laboratory in America. Optical microscopy has been used to examine qualitatively cracked and pristine material. Consequent on the manufacturing process, the explosive crystals display angular features and natural facets. In addition, considerable growth twinning, internal defects and voidage has been observed. These defects are found significantly to alter the failure path. In common with other PBXs, failure paths tend to run around the long straight edges of the explosive filler and avoid regions of fine filler and binder. Explosive crystals were found to fracture due either to cracks propagating from another region or internal defects. These observations are confirmed by the use of high–resolution moire interferometry. This sensitive optical technique allows the deformation of the sample to be measured up to and including the point of failure. By taking white–light micrographs that are in exact registration with the measured displacement maps, the influence of the underlying microstructure can be seen.

Zirconolite waste forms are advanced ceramic materials for the immobilisation of HLW, particularly actinides. This paper presents a systematic review of seven common substitution mechanisms of nuclear wastes in zirconolite, categorized into two types: charge-compensated substitution and direct substitution. For those substitution modes, three primary phase evolution pathways were identified: i zirconolite-2M to zirconolite-4M and/or to pyrochlore; ii zirconolite-2M to zirconolite-3O; iii zirconolite-2M to zirconolite-3T. The formation of zirconolite-3T or zirconolite-4M as intermediate phases is typically influenced by substitution behaviour, preparation conditions, or fabrication methods. Additionally, the substitution mechanisms of actinides (or REE analogue) in zirconolite were systematically investigated, corresponding to the seven substitution designs. Notably, the preferential occupation of An/REE in Ca sites was verified at simultaneous direct substitution in both Ca and Zr sites. Whilst extensive studies has explored An/REE substitution mechanisms in zirconolite and identified phase evolution pathways to zirconolite-3O, -3T, -4M, and pyrochlore, the substitution behaviour, radiation stability and chemical durability of these defect-fluorite derivatives warrant further systematic investigation.

The exceptional reactivity of the azide group makes organic azides a highly versatile family of compounds in chemistry and the material sciences. One of the most prominent reactions employing organic azides is the regioselective copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition with alkynes yielding 1,2,3-triazoles. Other named reactions include the Staudinger reduction, the aza-Wittig reaction, and the Curtius rearrangement. The popularity of organic azides in material sciences is mostly based on their propensity to release nitrogen by thermal activation or photolysis. On the one hand, this scission reaction is accompanied with a considerable output of energy, making them interesting as highly energetic materials. On the other hand, it produces highly reactive nitrenes that show extraordinary efficiency in polymer crosslinking, a process used to alter the physical properties of polymers and to boost efficiencies of polymer-based devices such as membrane fuel cells, organic solar cells (OSCs), light-emitting diodes (LEDs), and organic field-effect transistors (OFETs). Thermosets are also suitable application areas. In most cases, organic azides with multiple azide functions are employed which can either be small molecules or oligo- and polymers. This review focuses on nitrene-based applications of multivalent organic azides in the material and life sciences.

Thiahelicenes

Energetic materials are conventionally ignited by the application of heat to some part of an explosive target. This is most often provided by a flame or by electrical heating using a resistive wire. The material responds by thermally heating and starting a burning zone, which spreads out from the ignition point generating gas. In some cases this zone can accelerate (due to the effect of this gas) into a reactive shock wave, termed detonation. Lasers are used in a variety of applications to thermal heat a range of materials, and thus seem an obvious candidate to trigger chemical reaction in energetic ones. A light pulse offers several advantages over an electrical one, since it may be delivered down a path both immune to electrical effects and chemically stable. Thus, the triggering of safety apparatus (such as the firing of bolts on aircraft exits) represents a major thrust in the development of laser–triggered explosive devices. The energy of the pulse may be used in one of two ways to achieve these effects. In the first, the laser is shone directly upon the chemical medium, which absorbs the light at discrete wavelengths. In the second, it is used to vaporize a metallic flyer that is launched to impact on a target creating a high–pressure zone. Either mechanism starts the required reaction. However, when the pulse is delivered directly to the material, detonation is found to proceed immediately with no transition via burning. This makes the process inexplicable using present concepts. This review will address a range of the experiments conducted and theories developed for this novel field. However, it should be emphasized that the fundamental mechanisms remain to be fully explained making the application both academically stimulating as well as industrially important.

Unlocking the Friedel-Crafts arylation of primary aliphatic alcohols and epoxides driven by hexafluoroisopropanol

Melamine N-oxide based self-assembled energetic materials with balanced energy & sensitivity and enhanced combustion behavior

The Future of Synthesis Chemistry in Energetics

Hazard Assessments of Energetic Systems, A Field Still in Development

In recent decades, there has been considerable interest in investigating advanced energetic materials characterized by high stability and favorable energetic properties. Nevertheless, reconciling the conflicting balance between high energy and the insensitivity of such materials through traditional approaches, which involve integrating fuel frameworks and oxidizing groups into an organic molecule, presents significant challenges. In this study, we employed a promising method to fabricate high-energy-density materials (HEDMs) through the intermolecular assembly of variously substituted purines with a high-energy oxidant. Purines are abundant in nature and are readily available. A series of advanced energetic materials with a good balance between energy and sensitivity were prepared by the simple and effective self-assembly of purines with high-energy oxidants. Notably, these compounds exhibit incredibly improved crystal densities (1.80-2.00 g·cm-3) and good detonation performance (D: 7072-8358 m·s-1; P: 19.82-34.56 GPa). In comparison to RDX, these self-assembled energetic materials exhibit reduced mechanical sensitivities and enhanced thermal stabilities. Compounds 1-5 demonstrate both high energy and low sensitivity, indicating that self-assembly represents a straightforward and effective approach for developing advanced energetic materials with a balanced combination of energy and safety. Moreover, this study offers an avenue for synthesizing energetic materials based on naturally occurring compounds assembled through intermolecular attractions, thereby achieving a balance between energy and sensitivity along with versatile functionality.

Technologies for room-temperature self-healing polymer materials and their applications in energetic materials