Recent Advances in Understanding the Reactivity of Energetic Ionic Liquids in Propulsion Applications
AIR FORCE RESEARCH LAB EDWARDS AFB CA
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The interest in using energetic ionic liquids EILs to replace highly toxic and volatile hydrazine-based fuels stems from the inherently low vapor pressure of ionic liquids. Understanding the reactivity of EILs in propulsion applications has included both experimental and theoretical investigations, but is complicated by the fast and complex chemistry involved during ignition and combustion of the propellants. Recently, the availability of a polarizable continuum model variant called the generic ionic liquid GIL model, developed by Truhlar and co-workers, has enabled the investigation of anion properties such as basicity and nucleophilicity in the condensed phase. Both the basicity and nucleophilicity of the anion influence the thermal decomposition of ionic liquids and understanding basicity of the anion is important in interpreting hypergolic ignition mechanisms in dicyanamide-based EILs. An approach using the GIL has been developed to understand both basicity and nucleophilicity trends in EILs, the results of which are presented in this paper. Also, recent experimental investigations using reactive surface scattering techniques and tunable vacuum ultraviolet photoionization of catalytically decomposed aerosols of EILs will be discussed.
- Physical Chemistry