Energetic Materials Laboratory
Department of Chemistry
Indian Institute of Technology Kanpur, India
Dr. Srinivas Dharavath
Assistant Professor
Our research group will design and synthesize various nitrogen-rich azoles, fused and strained rings containing small molecules which are highly dense, thermally stable, and insensitive towards mechanical stimuli for 'Green' and 'Environmentally friendly' high energy materials (HEM) applications. So far, we have synthesized various poly-nitrogen containing small energetic molecules and salts from commercially available cheap starting materials as HEMs in a simple and straightforward manner. Few synthesized molecules are a better replacement for the existing benchmark energetic materials that meet the requirements of present and future civil, defense, and space applications.
Special Issue:
Design and synthesis of high-performing energetic materials
In material science, high energy materials (HEMs) are among the most essential functional substances and are widely utilized for various military and civilian purposes. HEMs are designed to store enormous amounts of energy in the chemical structure in a condensed phase releasing rapidly (in the case of an explosive) or gradually (in the case of propellants) and exerting abrupt change in heat-pressure on the surroundings. Since the discovery of black powder and the subsequent development of nitroglycerine, nitrocellulose, TNT, TATB, RDX, HMX, CL-20, etc., the demand for new materials has increased with desired properties for civil, defence, and space exploration programs.
HEMs with specific and modifiable physicochemical and energetic properties are essential for their precise applications. New HEMs with tunable performance and safety have been the subject of an extensive investigation by researchers worldwide. Some of the present challenges in the field of HEMs are (i) Demand for green energetic materials with nitrogen-rich heterocyclic backbone as a replacement for TNT, RDX and HMX since they produce an enormous amount of toxic gases (CO and CO2) on detonation. (ii) Insensitivity towards heat, impact, friction, and electrostatic discharge is an essential and fate-deciding parameter for HEMs. (iii) Development of higher-performing melt-castable ingredients that are more energetic than TNT and DNAN. (iv) Combining high performance with less sensitivity i.e., minimizing energy-safety contradiction.
The heterocyclic backbone plays an excellent role in the design and synthesis of HEMs. Developing new and convenient synthetic routes, high energy-safety balance, and environmentally benign nature has tremendous value to the wider materials community.
Guest Editor
Dr. Srinivas Dharavath
Assistant Professor
ORCID: 0000-0002-1680-7496
Recent Articles
Highly Dense N–N-Bridged Dinitramino Bistriazole-Based 3D Metal-Organic Frameworks with Balanced Outstanding Energetic Performance
Due to the inherent conflict between energy and safety, the construction of energetic materials or energetic metal-organic frameworks (E-MOFs) with balanced thermal stability, sensitivity and high detonation performance is challenging for chemists worldwide. In this regard, in recent times self-assembly of energetic ligands (high nitrogen and oxygen-containing small molecules) with alkali-metals were probed as a promising strategy to build high-energy materials with excellent density, insensitivity, stability, and detonation performance. Herein, based on the nitrogen-rich N, N'-([4,4'-bi(1,2,4-triazole)]-3,3'-dial)dinitramide (H2BDNBT) energetic ligand, two new environmentally benign E-MOFs including potassium [K2BDNBT]n (K-MOF) and sodium [Na2BDNBT]n (Na-MOF) have been introduced and characterized by NMR, IR, TGA-DSC, ICP-MS, PXRD, elemental analyses and SCXRD. Interestingly, Na-MOF and K-MOF demonstrate solvent-free 3D dense frameworks having a crystal density of 2.16 and 2.14 g cm-3, respectively. Both the E-MOFs show high detonation velocity (VOD) which is 8557‒9724 m/s, detonation pressure (DP) 30.41‒36.97 GPa, positive heat of formation (122.52‒242.25 kJ mol-1) and insensitivity to mechanical stimuli such as impact and friction (IS = 30‒40 J, FS > 360 N). Among them, Na-MOF has a detonation velocity (9724 m/s) superior to that of current conventional explosives. Additionally, Both the E-MOFs are highly heat-resistant having high decomposition (319 ℃ for K-MOF and 293 ℃ for Na-MOF) than the traditional explosives RDX (210 ℃), HMX (279 ℃), and CL-20 (221 ℃). This stability is ascribed to the extensive structure and strong covalent interactions between BDNBT2- and K(I)/Na(I) ions. To the best of our knowledge for the first time, we report dinitramino-based E-MOFs as highly stable secondary explosives, Na-MOF may serve as a promising next-generation high energy density material for the replacement of presently used secondary thermally stable energetic materials such as RDX, HNS, HMX, and CL-20.
Mixed-Metallic Energetic Metal-Organic Framework: New Structure Motif For Potential Heat-Resistant Energetic Materials
The incessant pursuit of heat-resistant explosives with balanced energetic performance and safety is indispensable in the civil and military sectors, particularly when employed in harsh environments. Herein, a new nanostructured highly energetic metal-organic framework (E-MOF), based on nickel(II) and sodium(I) mixed-metal has been constructed using an energetic poly tetrazole molecule by the hydrothermal approach. Na/Ni-MOF was thoroughly characterized using IR, TGA-DSC, SEM, and PXRD analyses. Further, the crystal structure was authenticated by single crystal X-ray diffraction analysis, and their crystal packing features were well explored, revealing a wave-like 3D framework having a crystal density of 1.985 g cm-3. This mixed-metallic E-MOF demonstrated good enthalpy of combustion (–7.91 kJ·g–1), good detonation velocity (VOD = 7410 m s-1) exceeding that of TNT (6820 m/s) and HNS (7164 m/s), excellent insensitivity (IS > 40 J; FS > 360 N). Additionally, it exhibits outstanding thermal stability (Td = 387 ⁰C). These fine-tuned properties are superior to those of continuously used benchmark heat-resistant explosives HNS, and TATB, suggesting that newly reported poly-tetrazole-based E-MOF is beneficial for improved physical performance. Given results in the present work, highlighted the advantages of mixed-metallic E-MOF as a potential heat-resistant explosive for future applications.