A comprehensive study of {γ-butyrolactone + 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide} binary mixtures

Density, electrical conductivity and viscosity of binary liquid mixtures of γ-butyrolactone, (GBL) with 1-methyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide, [pmim][NTf2], were measured at different temperatures from (293.15 to 323.15) K and at atmospheric pressure (p = 0.1 MPa) over the whole composition range. Excess molar volumes have been calculated from the experimental densities and were fitted with Redlich-Kister's polynomial equation. Other volumetric properties have been also calculated in order to obtain information about interactions between GBL and selected ionic liquid. All the results are compared with those obtained for binary mixtures of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [bmim][NTf2], with GBL. From the viscosity measurements, the Angell strength parameter was calculated for pure ionic liquid indicating that [pmim][NTf2] is a “fragile” liquid. Electrical conductivity results were discussed in the scope of Bahe-Varela theoretical model.