Ionic Conductivity and Aggregation Behavior of N,N-Dimethylethanolammonium Carboxylate Protic Ionic Liquids in Aqueous, Ethanolic, and Acetonitrile Solutions

Abstract

The electrical conductivity of ionic liquids (ILs) is an important figure of merit for any electrochemical application. In this regard, we measured electrical conductivities of N,N-dimethylethanolammonium based PILs at different temperatures from T = 293.15–323.15 K, and the results are discussed in terms of the effect of temperature, hydrophobicity, and H-bonding abilities of ions on conductivity. The investigation into alterations in the electrical conductivity of ionic liquids (ILs) in both polar protic and aprotic solvents holds significant importance for advancing the industrial applications of IL solutions. To broaden the potential applications of ILs, we conducted measurements of the specific conductivity (κ) in binary mixtures involving N,N-dimethylethanolammonium carboxylates [DMEA] [Carboxylates], a protic ionic liquids (PILs), with water, ethanol, and acetonitrile at 298.15 K. The aggregation behavior of the PILs in various solvents was studied by determining the critical aggregation concentration (CAC), and standard Gibbs energy of aggregation \((\Delta G_{{\text{a}}}^{^\circ })\). The findings from studies on the electrical conductivity of mixtures involving [DMEA] [Carboxylates] with molecular solvents are analyzed with a focus on ion-solvent interactions. The discussions encompass the impact of hydrophobicity, as well as the influence of H-bonding abilities exhibited by both the ionic liquid (PIL) and the solvent on the aggregation behavior observed in the mixtures.