Transport Properties in Protic and Aprotic Ionic Liquids

Abstract

We have made several studies of the transport properties of ionic liquids, the viscosity (η), molar conductivity (Λ), and ion self-diffusion coefficients (DSi), at atmospheric as well as high pressures [1-4]. The data have been analyzed in terms of the Stokes-Einstein-Sutherland (SES) relation, linking DSi with η, the Walden relation, linking Λ with η, and the Nernst-Einstein (NE) relation, linking Λ with DSi. These relations are empirical as for ionic liquids, but showed certain patterns. The SES plots, ln(DSi/T) vs. ln(1/η), provided the straight lines with the slopes t being slightly smaller than unity. The very similar results were obtained for the Walden plots, ln(Λ) vs. ln(1/η). These two relations bring about the linear correlations between ln(ΛT) and ln(DS+ + DS-) with the slopes t very close to unity, which implies that the deviation parameters Δ in the NE relation are independent of temperature and pressure. This correlation is also useful to verify the consistency of the experimental results. Based on the above-mentioned transport properties, we further calculated and discussed the velocity cross-correlation coefficients for like and unlike ion interactions and the Laity resistance coefficients. In the present talk, we attempt to extend such phenomenological aproach to protic ionic liquids as well as typical aprotic ionic liquids