The Apparent Superionicity of Ionic Liquid Solutions Containing Cellulose

In this study, we evaluated the molar conductivity and dynamic viscosity of 1-ethyl-3-methylimidazolium acetate based solvent systems containing dissolved cellulose (cotton or microcrystalline cellulose), cellobiose, or glucose. Matrix variables included solute concentration, as well as concentration of acetonitrile or water (typical molecular species present in IL-based biopolymer solutions). Ion conductivity, dynamic viscosity, and density were measured for each solution, and the data was correlated graphically on Walden plots. When this approach is used, the systems containing dissolved cellulose appear superionic. This apparent superionicity results from large (up to 140-fold) increases in solution viscosity due to dissolved biopolymer, and correspondingly small (ca. 0.7-fold) decreases in solution conductivity. Differences in solution hydroxyl content as well as cellulose content and degree of polymerization are proposed as the physical explanation behind the apparent superionic behavior. (C) The Author(s) 2019. Published by ECS.