Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session H2: Energetic and Reactive Materials: Synthesis and New Molecules II |
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Chair: Virginia Manner, Los Alamos National Laboratory Room: Grand Ballroom AB |
Tuesday, July 11, 2017 9:15AM - 9:45AM |
H2.00001: Synthesis of High-Energy CHNO Materials: Rational Design through Consultation with Formulators Invited Speaker: Jesse Sabatini There is an ongoing quest to synthesize new energetic materials that have densities, detonation pressures, detonation velocities and specific impulses that are as high as possible. While this is a noble goal that should still be pursued, there is the tendency to overlook real world attributes required for potential applications. As such, many of the materials that are being synthesized, while perhaps garnering a lot of scientific press based on calculated performance, will not ultimately prove to be useful when formulated. In designing new CHNO ingredients, careful consideration of its final potential application allows the tailoring of syntheses in an effort to help meet pressing needs and to address capability gaps. Discussed will be the syntheses of several isoxazole- and 1,2,4-oxadiazole-based energetic materials, which were designed based on their promising attributes as compared to similar problematic heterocycles. These ring systems were carefully selected based on chemical intuition. The materials were prepared in high yields using simple processes, and displayed expectedly low sensitivities to impact, friction and electrostatic discharge. The calculated performances of these materials, and their potential applications will be discussed. [Preview Abstract] |
Tuesday, July 11, 2017 9:45AM - 10:00AM |
H2.00002: The Quest for Greater Chemical Energy Storage II: On the Relationship between Bond Length and Bond Energy Michael Lindsay, Robert Buszek, Jerry Boatz, Mario Fajardo This is the second in a series of papers aimed at exploring the fundamental limitations to chemical energy storage. In the previous work, we summarized the lessons learned in various high energy density materials (HEDM) programs, the different degrees of freedom in which to store energy in materials, and the fundamental limitations and orders of magnitude of the energies involved.$^{\mathrm{1}}$ That discussion focused almost exclusively on the topic of molar energy density (J/mol) from the perspective of the energy of oxidation of the elements and Fritz Zwicky's ``free atom limit.''$^{\mathrm{2}}$ In this talk, we extend the analysis by considering a different, though equally important, aspect of the energy density calculation: the volumetric density of the energetic material. Specifically, we examine how the distances between individual atoms (i.e. intra- and inter-molecular bond lengths) are coupled to (in fact, approximately inversely proportional to) the energy stored in the bonds of the molecule. This relationship further limits the chemical energy that theoretically can be stored in a material below that predicted by the ``free atom limit.'' This talk will give specific examples of the trends with different bonding motifs and the implications to the fundamental limitations of chemical energy storage. [Preview Abstract] |
Tuesday, July 11, 2017 10:00AM - 10:15AM |
H2.00003: New Imidazole-based High Nitrogen Energetic Materials G. Kenneth Windler, Philip Leonard, Maxwell Schulze, Ernest Hartline Energetic materials derive their power from energy release, usually in the form of gaseous products. The type and quantity of these products contribute to performance and detonation parameters. In particular, high-nitrogen materials produce large quantities of elemental nitrogen, and can be tuned via molecular structure for suitability as propellants (gas generators) or explosives. In this work, the five-membered nitrogen heterocycle imidazole is used as a substrate for a variety of high-nitrogen materials. Substitution of the imidazole ring directly with nitro-, azido-, diazo-, and tetrazole moieties allows for tunable properties of the resultant energetic material. Properties can be further tailored by salt formation at the acidic proton(s) on the molecules. The various combinations of these derivatives are presented, along with the substitution effects on physical, chemical, and explosive properties. [Preview Abstract] |
Tuesday, July 11, 2017 10:15AM - 10:30AM |
H2.00004: Abstract Withdrawn
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Tuesday, July 11, 2017 10:30AM - 10:45AM |
H2.00005: First Principles Investigation of Nitrogen-Rich Energetic Materials Brad Steele, Ivan Oleynik Energetic materials rich in nitrogen hold great promise due to their high positive heats of formation and because the products of detonation consist mostly of environmentally-friendly N$_{\mathrm{2}}$ gas. Pure polymeric nitrogen can be synthesized at high pressures, although it has yet to be quenched to ambient conditions. By introducing a reducing agent into the crystal structure, the stability of polynitrogen compounds can be enhanced. We have investigated the stability of alkali polynitrides (R$_{\mathrm{x}}$N$_{\mathrm{y}})$, as well as hydro-nitrogens (H$_{\mathrm{x}}$N$_{\mathrm{y}})$, at high pressures and found several stable crystal structures that contain N$_{\mathrm{5}}$ rings, N$_{\mathrm{6}}$ rings, N$_{\mathrm{4}}$ chains, and polymeric nitrogen chains. Using our theoretical input, cesium pentazolate salt has been synthesized for the first time by our experimental collaborators. We also consider several other ternary high-nitrogen energetic materials, containing \textbraceleft C, O, N\textbraceright and \textbraceleft H, O, N\textbraceright atoms. The results demonstrate the great potential for first principles structure prediction to design new energetic compounds and crystal structures, which are better, safer, and greener than traditional CHNO energetic materials. [Preview Abstract] |
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