Deuterated energetic materials: Syntheses, structures, and properties

Abstract

The deuteration of energetic materials contributes to high signal-to-noise ratios (SNRs) in neutron diffraction, thus allowing the structures of energetic materials to be effectively investigated. This study developed the synthesis methods of deuterated energetic materials through chemical synthesis or newly developed one-pot H/D exchange. Using these methods, it synthesized nine deuterated energetic materials in a concise and low-cost manner: deuterated 1,3,5-triamino-2,4,6-trinitrobenzene (TATB-d₆, 1), 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX-d₈, 2), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX-d₆, 3), dihydroxylammonium 5,5′-bis(tetrazole-1-oate) (TKX-50-d₈, 4), nitroguanidine (NQ-d₄, 5), 1,1-diamino-2,2-dinitroethylene (FOX-7-d₄, 6), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105-d₄, 7), trinitrotoluene (TNT-d₃, 8), and 3-nitro-1,2,4-triazol-5-one (NTO-d₂, 9). Furthermore, the single crystals of HMX-d₈ (2) and RDX-d₆ (3) were obtained, and the α-, β-, γ-, and δ-polymorphs of HMX-d₈ (2) were prepared accordingly. The deuterated energetic materials were characterized and analyzed using infrared spectroscopy (IR), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), X-ray diffraction (XRD), and neutron diffraction. Besides, this study determined the decomposition activation energy (E_a), pre-exponential factor (A), decomposition rate constant (k), and critical explosion temperature (T_b) of TATB-d₆ (1), HMX-d₈ (2), and RDX-d₆ (3) via DSC experiments at different heating rates. The NMR and neutron diffraction data show that these deuterated energetic materials have high deuteration rates of more than 95%. The DSC and TG analyses indicate that the deuterated energetic materials exhibit slightly higher decomposition temperatures than their nondeuterated counterparts. Furthermore, neutron diffraction shows that the deuterated energetic materials feature high SNRs.