(643c) Characterization of 1-Ethyl-3-Methyl-Imidazolium Ionic Liquid Behavior in Non-Aqueous Solvents

We characterize binary systems of 1-Ethyl-3-methyl-imidazolium [emim]⁺ ionic liquids (ILs) with various molecular solvents including; glycerol, ethylene glycol, acetonitrile, and triethanolamine using precise measurement techniques to determine the conductivity, viscosity, and density of these systems across a wide IL concentration range. We use these three properties in conjunction with the estimated Stoke’s radii of the ions calculated from the ubiquitous UNIQUAC and UNIFAC and values, to estimate the ion dissociation based on a method previously described in our previous work.^1,2 Additionally we explore the role of hydrogen bonding in these systems by measuring excess enthalpy across a wide range of IL concentrations. These measurements offer new insights into the driving forces behind ion pair formation in IL/solvent systems. We further consider the solvent effects on ion pair formation, by studying solvents with similar dielectric constants and vary structure (i.e. glycerol, triethanolamine, and ethylene glycol) as well as solvents with similar structure and different dielectric constants (i.e. triethanolamine and glycerol).

(1) Nordness, O.; Simoni, L. D.; Stadtherr, M. A.; Brennecke, J. F. Characterization of Aqueous 1-Ethyl-3-Methylimidazolium Ionic Liquids for Calculation of Ion Dissociation. J. Phys. Chem. B 2019, 123, 1348–1358. https://doi.org/10.1021/acs.jpcb.8b11892.

(2) Simoni, L. D. Predictive Modeling of Fluid Phase Equilibria for Systems Containing Ionic Liquids, University of Notre Dame, Indiana, 2009.