Introduction: This new class of Ionic Liquids (ILs) can potentially create a new, rapid means of separating biomolecules such as proteins that is faster than chromatography and other well established methods. This is also a major advance in that the new ILs should provide a platform to investigate enzyme catalyzed reactions in ionic liquids and should serve as model systems for cell membranes for thermodynamic and transport processes. The development of these new ILs could result in more environmentally benign and economical processes.

Intellectual Merit: Ionic liquids (ILs) are organic salts, which are liquids at temperatures below 100°C. They are a unique class of compounds that are essentially non-volatile and have highly tunable properties. As one might expect, ionic liquids typically exhibit the same solvent characteristics as polar molecular solvents, readily dissolving moderately-polar and polar solutes (like-dissolves-like) but often being poor solvents for non-polar compounds. This limits the applicability of ILs for chemical reactions and separations processes that involve non-polar compounds, including those of biological origin such as fatty acids and cholesterol. We have developed a new class of ILs that contains long alkyl chains, incorporated to impart non-polar-like solvent properties, which remain room temperature liquids. Typically, ILs with long alkyl chains remain solids at room temperature due to the enhanced interactions created by the long chains; however, our recent work has overcome this problem. We accomplished this by taking cues from biological systems, i.e. the manner in which certain organisms regulate membrane fluidity in colder temperatures by including unsaturation in the alkyl chains of phospholipids. Like these ionic liquids, phospholipids are charged species with long alkyl chains. In this work we propose to study the thermophysical behavior of these ILs as pure components and in binary mixtures with non-polar solutes to examine how they may be used in separations processes in the chemical and pharmaceutical industries.

Having demonstrated this phenomenon in a recent publication, we now propose to study the thermophysical properties of an expanded set of non-polar-like room temperature ionic liquids and to study the solvent and solution thermodynamic properties of the entire class of species. We hypothesize that incorporating these long non-polar alkyl chains, while maintaining low melting points, will result in ILs that can exhibit non-polar-like solvent properties and potentially have the capability to separate non-polar solutes based on the sizes and shapes of the non-polar domains present in the liquid. Such ionic liquids would open the door to new areas of research including more environmentally benign and economical processes involving non-polar molecules that are currently not possible due to solubility limitations. Additionally, we anticipate that these ionic liquids will provide a platform for researchers to investigate a broader class of enzyme catalyzed reactions in ionic liquids, and they may serve as excellent model systems for cell membranes for thermodynamic and transport processes. At the University of South Alabama, we have pioneered the development of several novel classes of ionic liquids including Brønsted acidic ILs and Lewis basic ILs that chemically capture CO2, which have been licensed for commercial production and sale. With the recently initiated collaboration between the departments of Chemical & Biomolecular Engineering and Chemistry, we are well equipped to advance our research to the next level.

Broader Impacts:

As ILs are essentially non-volatile, as compared to volatile molecular solvents, technologies enabled by the development of these new species will result in more environmentally benign processes. Also, this work constitutes a new line of research at the University of South Alabama that stems from the collaboration between Chemical & Biomolecular Engineering and Chemistry and will enhance interdisciplinary efforts in this direction. Coupling the engineering component to the in-place expertise in synthesis will enable us to be more internationally competitive. Also, with these molecules sufficiently characterized, researchers around the world will have access to a novel and scientifically rich resource currently absent from the possibilities offered by ILs.

The undergraduate and graduate research students will be directly involved in conducting this research and will benefit from the cross-disciplinary training as they work as a unified team. The project will be incorporated into pedagogy as research activities are integrated into the undergraduate and graduate curricula. Because USA is an EPSCoR state institution serving many students in the greater Gulf Coast region from historically underrepresented groups, this project will allow those students who have not traditionally had access to this level of technological sophistication to actively participate in research. Additionally, the outreach effort (YouTube videos with downloadable classroom content) stemming from this work will help demonstrate the societal value of science and engineering to K-12 students, and motivate them to engage in careers in STEM related fields.

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University of South Alabama
United States
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