http://www.sciencemadness.org/talk/files.php?pid=302583&aid=26587

Azole-based energetic salts.

Advances in science and technology of modern energetic materials: an overview.

Environmentally compatible next generation green energetic materials (GEMs).

Fireworks are probably the application of chemistry which resonates best with the general public. However, fireworks and (civil and military) pyrotechnic applications cause environmental pollution and thus have given rise to the development of new, environmentally friendly pyrotechnic compounds and formulations. Nitrogen-rich energetic materials, such as the derivatives of tetrazoles and tetrazines, are about to revolutionize traditional pyrotechnic compositions. This Review summarizes the sources of pollution in current formulations and recent efforts toward "green" pyrotechnics.

Green Pyrotechnics : A Chemists' Challenge

In this contribution we report on the synthesis and full structural as well as spectroscopic characterization of 3,3'-dinitro-5,5'-bis-1,2,4-triazole-1,1'-diol and nitrogen-rich salts thereof. The first synthesis and characterization of an energetic 1-hydroxy-bistriazole in excellent yields and high purity is presented. This simple and straightforward method of N-oxide introduction in triazole compounds using commercially available oxone improves the energetic properties and reveals a straightforward synthetic pathway toward novel energetic 1,2,4-triazole derivatives. X-ray crystallographic measurements were performed and deliver insight into structural characteristics and strong intermolecular interactions. The standard enthalpies of formation were calculated for all compounds at the CBS-4 M level of theory, revealing highly positive heats of formation for all compounds. The energetic properties of all compounds (detonation velocity, pressure, etc.) were calculated using the EXPLO5.05 program, and the ionic derivatives show superior performance in comparison to the corresponding compounds bearing no N-oxide. All substances were characterized in terms of sensitivities (impact, friction, electrostatic) and thermal stabilities, and the ionic derivatives were found to be high thermally stable, insensitive compounds that are exceedingly powerful but safe to handle and prepare.

A study of dinitro-bis-1,2,4-triazole-1,1'-diol and derivatives: design of high-performance insensitive energetic materials by the introduction of N-oxides.

This paper reviews the research and development work on CL-20, the most powerful high-energy material of today, as well as CL-20-based formulations. Methods of CL-20 synthesis and processes for obtaining a desired particle size are discussed. Particular attention is paid to optimization of conditions for obtaining the most stable high-density polymorph. The Fourier Transform Infrared spectroscopy and X-ray diffraction appear to be effective means for distinguishing CL-20 polymorphs. The thermal decomposition pattern of CL-20 as well as the proposed decomposition and combustion mechanisms also form part of this manuscript. Investigations performed by various researchers show that its relatively high sensitivity needs special attention from the viewpoint of CL-20 preparation and processing of formulations based on this substance. Salient features of CL-20-based explosives and gun/rocket propellants studied are included into this review. CL-20 may be ranked as the most attractive compound for futuristic explosive and propellant formulations. The research activities performed by the authors on synthesis and characterization of CL-20 are briefly described.

Hexanitrohexaazaisowurtzitane (CL-20) and CL-20-based formulations (review)

CL-20 is an attractive HEM having density (>2 g cm-3) and velocity of detonation (9400 m s-1) superior to HMX (1.9 g cm-3 and 9100 m s-1). During this study, CL-20 was synthesized to establish viability of efficient synthesis method. The compound synthesized at HEMRL was characterized by FTIR, 1H NMR and elemental analysis. Thermal studies (dynamic DSC and isothermal TG) were undertaken to determine kinetic parameters and understand the decomposition patterns. An attempt is made to explain the mechanism of decomposition of CL-20 on the basis of the data obtained by the authors and findings of other researchers. The activation energy values obtained during this work by adopting various approaches are close to the values reported for N-NO2 bond cleavage suggesting that it is global rate determining process rather than the collapse of cage structure. Mass spectra also provides evidences in this regard. Monitoring of decomposition products at high temperature supports these findings and brings out that NO2 initiates secondary decomposition processes because of entrapment in cage structure.

Studies on cl-20: the most powerful high energy material

This paper reviews the current status and future trends of aluminized explosives. The major focus is on cast compositions, which encompass both the melt-cast trinitrotoluene (TNT) based and the slurry cast polymer-based compositions. Widely reported RDX and HMX based aluminized compositions with TNT used as a binder are discussed in detail. Various researchers have suggested a 15–20% Al content as an optimum from the viewpoint of velocity of detonation. A higher Al content, however, is incorporated in most of the compositions for a sustained blast effect, due to the potential of secondary reactions of Al with detonation products. The effect of the aluminum particle size on performance parameters (velocity of detonation, etc.) is included. There are some recent works on nanometric Al based compositions, and the results obtained by various researchers suggest mixed trends for RDX-TNT compositions. Studies on nitrotriazol and TNT based compositions bring out their low vulnerability. Some of the interesting findings on ammonium dinitramide and bis(2,2,2-trinitro-ethyl)nitramine (BTNEN) based compositions are also included. The review brings out superiority of polymer based aluminized explosives, as compared to conventional TNT based compositions, particularly, with respect to low vulnerability. In general, aluminized plastic bonded explosives find numerous underwater applications. Ammonium perchlorate (AP) is also incorporated, particularly, for enhancing underwater shock wave and bubble energy. Hydroxyl terminated polybutadiene appears to be the binder of choice. However, nitrocellulose, polyethylene glycol, and polycaprolactone polymer based compositions with energetic plasticizers, like bis-dinitropropyl acetal/formal (BDNPA/F, 1/1 mix), trimethylol ethane trinitrate, and triethylene glycol dinitrate are also investigated. Polyethylene glycol and polycaprolactone polymer based compositions are found to be low vulnerable, particularly, in terms of shock sensitivity. Highly insensitive polymer bonded nitrotriazol based compositions are being pursued all over the globe. The highly insensitive CL-20/AP combination meets the demands of high density and high velocity of detonation. Glycidyl azide polymer and poly nitratomethyl methyl oxetane appear to be binders of interest for plastic bonded explosives in view of their superior energetics. The vulnerability aspects of these compositions, however, need to be studied in detail. Brief information on plastic bonded and gelled thermobaric explosives is also included.

Cast aluminized explosives (review)

Research and development efforts for realizing higher performance levels of high energy materials (HEMs) are continued unabated all over the globe. Of late, it is becoming increasingly necessary to ensure that such materials are also eco-friendly. This has provided thrust to research in the area of force multiplying HEMs and compounds free from pollution causing components. Enhancement of the performance necessitates introduction of strained structure or increase in oxygen balance to achieve near stoichiometry. The search for environment friendly molecules is focused on chlorine free propellant compositions and lead free primary explosives. Energetic polymers offer added advantage of partitioning of energy and thus not necessitating the concentration of only solid components (HEMs and metal fuels) in the formulations, to achieve higher performance, thereby leading to improvement in energetics without adversely affecting the processability and mechanical properties. During recent times, research in the area of insensitive explosives has received impetus particularly with the signature of STANAG. This paper gives a review of the all-round advances in the areas of HEMs encompassing oxidizers, high-energy dense materials, insensitive high-energy materials, polymers and plasticizers. Selected formulations based on these materials are also included. Defence Science Journal, 2010, 60(2), pp.137-151 , DOI:http://dx.doi.org/10.14429/dsj.60.327

https://www.publications.drdo.gov.in/ojs/index.php/dsj/article/download/327/193

S. N. Asthana

Papers

Advances in science and technology of modern energetic materials: an overview.

Hexanitrohexaazaisowurtzitane (CL-20) and CL-20-based formulations (review)

Studies on cl-20: the most powerful high energy material

Cast aluminized explosives (review)

Advances in High Energy Materials (Review Paper)