Partial Phase Behavior of HMX/DMSO Solutions

Hoffman, D. Mark; Swansiger, Rosalind W.

doi:10.1002/(sici)1521-4087(199910)24:5<301::aid-prep301>3.0.co;2-j

Cited by 6 publications

(2 citation statements)

References 3 publications

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“…Thus, we believe the δ-HMX deposits on UIUC crystals grown in acetone or acetonitrile were formed during solution crystallization when the mother liquor evaporated to dryness or when a crystal was removed from the mother liquor and tiny droplets of the liquor clinging to the crystal face evaporated quickly. The situation with DMSO-grown crystals, such as those obtained from LANL, is much more complicated due to the unusual phase diagram for HMX/DMSO solutions, in which a solvated crystal containing HMX cocrystallized with two DMSO molecules has been observed . Curiously, when a solution with these solvated crystals was allowed to evaporate slowly, the residue contained β-HMX, α-HMX, and γ-HMX, but no δ-HMX.…”

Section: Discussionmentioning

confidence: 99%

“…The situation with DMSO-grown crystals, such as those obtained from LANL, is much more complicated due to the unusual phase diagram for HMX/DMSO solutions, in which a solvated crystal containing HMX cocrystallized with two DMSO molecules has been observed. 33 Curiously, when a solution with these solvated crystals was allowed to evaporate slowly, the residue contained β-HMX, R-HMX, and γ-HMX, but no δ-HMX. This observation suggests that it is rapid solvent evaporation that is needed for the formation of δ-HMX surface deposits.…”

Section: Discussionmentioning

confidence: 99%

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Surface Nonlinear Vibrational Spectroscopy of Energetic Materials: HMX

et al. 2007

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The surfaces of solution-grown β-HMX (β-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) crystals were studied using vibrational sum-frequency generation spectroscopy (SFG). In earlier work (Kim, H.; Dlott, D. D. Propellants, ExplosiVes, Pyrotechnics 2005, 31, 116), such SFG spectra evidenced considerable variability as the ∼200-µm diameter laser beam was translated over crystal surfaces. We have now found this variability results from ubiquitous small deposits of δ-HMX on the surface of β-HMX single crystals. SFG is a selective probe of molecules in noncentrosymmetric environments. Since β-HMX is centrosymmetric, only the surface is SFG-active; however, δ-HMX is noncentrosymmetric, so a tiny δ-HMX deposit on a β-HMX surface could dominate the SFG spectrum. We have found that rapid evaporation from tiny droplets of HMX solution produces only δ-HMX, presumably because the polar boat conformation of δ-HMX is stabilized in solution. We believe the δ-HMX deposits are created by the rapid drying of droplets of mother liquor clinging to solution-grown crystal surfaces. In this paper, we present SFG spectra of δ-HMX nanocrystals and β-HMX surfaces in the CH-stretch and NO 2 -stretch regions. Through an analysis of the β-HMX/δ-HMX SFG intensity ratios and the surface variability, we deduce that the δ-HMX deposits we observe have dimensions of a few micrometers and a mean surface coverage that, depending on crystal growth conditions, ranges from 0.1 to 1 µg/cm 2 . The implications of these δ-HMX sites for energetic material performance are discussed briefly.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Surface Nonlinear Vibrational Spectroscopy of Energetic Materials: HMX

et al. 2007

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Patterning High Explosives at the Nanoscale

Nafday

Pitchimani

Weeks

et al. 2006

Propellants Explo Pyrotec

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For the first time, we have shown that spin coating and Dip pen nanolithography (DPNTM) are simple methods of preparing energetic materials such as PETN and HMX on the nanoscale, requiring no heating of the energetic material. Nanoscale patterning has been demonstrated by the DPN method while continuous thin films were produced using the spin coating method. Results are presented for preparing continuous PETN thin films of nanometer thickness by the spin coating method and for controlling the architecture of arbitrary nanoscale patterns of PETN and HMX by the DPN method. These methods are simple for patterning energetic materials and can be extended beyond PETN and HMX, opening the door for fundamental studies at the nanoscale.

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