The most comprehensive approach to analyze and characterize energetic materials is suggested and applied to enable rational, rigorous design of novel materials and targeted improvements of existing materials to achieve desired properties. We report synthesis, characterization of the structure and sensitivity, and modeling of thermal and electronic stability of the energetic, heterocyclic compound, 3,4-bis(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole-2-oxide (BNFF). The proposed novel, relatively simple synthesis of BNFF in excellent yields allows for an efficient scale up. Performing careful characterization indicates that these materials offer an unusual combination of properties and exhibit a relatively high energy density, high and controllable stability against decomposition, low melting temperature, and low sensitivity to initiation of detonation. First-principles calculations of activation barriers and reaction rate constants reveal the decomposition scenarios that govern the thermal stability and chemical behavior of BNFF, which appreciably differ from conventional nitro compounds. Details of the electronic structure and calculated electronic properties suggest that BNFF is an excellent candidate energetic material on its own and an attractive ingredient of modern energetic formulations to improve their stability and enable highly controllable chemical decomposition.
A methodology
to design novel energetic materials by means of a
holistic approach that links synthesis, experimental characterization,
quantum-chemical modeling, and statistical empirical evaluation is
proposed. An analysis of the revealed structure–property–function
correlations in the LLM compound series (oxadiazole-based heterocyclic
energetics), BNFF, BNFF-1, LLM-172, LLM-191, and LLM-192, led us to
predict, obtain, and characterize a new member in the materials family,
LLM-200, which exhibits attractive energetic characteristics compared
to known conventional high energy density materials. While the applied
strategy convincingly demonstrated feasibility of the end-to-end design
of high energy density materials, there are certain limitations in
parallel improvements of sensitivity and performance within a single
compound.
Real-time measurements of the product gases arising from the thermal decomposition of triamino-trinitro benzene (TATB), its deuterated analogue, and plastically bonded TATB (LX-17) are presented in this study. Gas-phase decomposition products are identified by IR absorption spectroscopy. The frequency shifts in rovibrational spectra due to isotopic substitution and the change in rate of formation of decomposition products due to the kinetic-isotope-effect (KIE) help elucidate the decomposition pathways. The formation of H 2 O precedes other molecules (e. g., HCN, HNCO) during decomposition. After the concentrations of HCN and HNCO molecules reach a peak, their amounts gradually decrease. The concentrations of the other decomposition products (e. g., NH 3 and CO 2 ) rapidly rise after an induction period, which is attributed to the presence of autocatalytic reactions. The trends of chemical evo-lution are similar for all the samples, but their kinetic behaviors are different. This indicates the rates of consistent pathways are changed during thermal decomposition. The kinetics of deuterated TATB decomposition is slower than that of unsubstituted TATB due to the KIE (k H /k D~1 .41). The rate of LX-17 decomposition is slightly lower than unsubstituted TATB (k TATB /k LX-17~1 .15). The KIE is more pronounced during the early stage of decomposition, which is attributed to the first steps of TATB decomposition involving water formation (i. e., H vs D transfer). The KIE slows down the formation of all gases, including those lacking hydrogen (e. g., CO 2 ). These results suggest the TATB thermal decomposition mechanism might involve a series of pathways rather than a set of independent and parallel reactions.
The title compound 3-(4-amino-1,2,5-oxadiazol-3-yl)-4-(4-nitro-1,2,5oxadiazol-3-yl)-1,2,5-oxadiazole (ANFF-1) was synthesized by: (1) by reaction of 3,4-bis(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole (BNFF-1) with gaseous ammonia in toluene and (2) by partial oxidation of 3,4-bis(4-amino-1,2,5-oxadiazol-3-yl)-1,2,5oxadiazole (BAFF-1) with 35% H 2 O 2 in concentrated H 2 SO 4 .
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