Ionic Liquids of Improved Thermal Stability

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In this project, funded by the Chemical Structure, Dynamics and Mechanism B Program of the Chemistry Division, Professor James Davis and his students of the Department of Chemistry at the University of South Alabama will explore the synthesis, characterization, and properties of a new type of ionic liquids (liquid salts). The liquid salts to be investigated are expected to be highly resistant to heat and to retain their liquid character, without evaporation, decomposition, or flammability, for long periods of time. Salts of this type can, in principle, be used as substitutes for more traditional liquids in applications ranging from heat transfer fluids and high-performance lubricants to biomass processing and the synthesis of important electronic materials such as semiconductors. The project brings together elements of chemical synthesis as well as material science and engineering, and offers engaged students a broad opportunity for gaining experience from a spectrum of activities. Since the institution at which the research will take place serves a high proportion of individuals from groups underrepresented in the sciences and engineering, the present project will provide important opportunities to engage in the professional training of individuals from these communities.Ionic liquids (ILs) are materials of considerable fundamental interest and growing practical utility. Because of their non-volatility, ionic liquids can be used in applications requiring high temperatures, such as in heat transfer, lubrication, or high-temperature materials synthesis. Although typical ILs have relatively high degrees of thermal stability, they are still incapable of being used for long durations at temperatures above 200 degrees Celsius. In the present project, ILs will be prepared using the tetraphenylphosphonium cation and derivatives thereof. Preliminary work has revealed that the former cation is stable to temperatures in excess of 300 degrees Celsius for days without decomposition or evaporation. Building on these findings, the mechanism by which thermal decomposition eventually does occur will be studied, and that knowledge will be harnessed to create salts of still higher thermal stability. In addition to creating new molten salts of high thermal stability, the use of these liquids in facilitating the rapid pyrolysis of biomass (for production of bio-oil) and in the thermal synthesis of electronically important materials such as ZnS and CdSe will be investigated.