Volumetric Properties, Molar Surface Gibbs Energy, and Its Application of Binary Systems Containing Ether-Group Functionalized Ionic Liquid with Monohydric Alcohols

Ether-group functionalized ionic liquid N-(2-methoxyethyl)-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [C1OC2pyrr][NTf2], was synthesized and characterized by 1H NMR, 13C NMR, and TGA. The density and surface tension of binary mixtures including [C1OC2pyrr][NTf2] and monohydric alcohols were measured over the entire range of mole fractions in different temperatures. Based on the experimental data of density and surface tension, the volumetric and surface properties of [C1OC2pyrr][NTf2] and its binary mixtures were obtained, and Vm, αp, and VE were explored. The effects of temperature and composition on these properties were investigated, and the excess molar volume of two binary mixtures was well fitted by the Redlick-Kister equation. The molar surface Gibbs energy (gs) of [C1OC2pyrr][NTf2] and its binary mixtures was calculated, and the traditional Eötvös equation was modified; moreover, all parameters had a clear physical meaning. Finally, based on gs, the surface tension of [C1OC2pyrr][NTf2] and its binary mixtures was estimated, and it is in good agreement with experimental values.