title: Macroscopic and microscopic study of 1-ethyl-3-methyl-imidazolium acetate-DMSO mixtures.
abstract: Macroscopic (steady-state viscosity, density) and microscopic (NMR chemical shifts, (1)H NMR relaxation times, and diffusion) properties of the 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc])-dimethyl sulfoxide (DMSO) mixture were studied in detail as a function of DMSO molar fraction at various temperatures. Temperature dependencies were used to calculate the activation energies. NMR results indicate that at low molar fraction of DMSO (<0.4), it weakly associates with the cation and in doing so disrupts the strong ion-ion association that exists in the pure ionic liquid. Stokes-Einstein equation, which linearly correlates the diffusion coefficient of a spherical molecule and macroscopic viscosity, was shown to work well for the [EMIM][OAc]-DMSO mixture. The influence of DMSO on the "anomalous" diffusion in [EMIM][OAc] ("quick" cation vs "slow" anion) was investigated; it was demonstrated that DMSO makes the cation diffusion slower. All parameters studied showed relatively small deviations from the ideal mixing rule behavior (from 20% to 50% difference between experimental and theoretically predicted results), confirming weak interactions between the components.
authors.affiliation: Soft Matter Physics Research Group, School of Physics and Astronomy, University of Leeds , Leeds LS2 9JT, United Kingdom.
authors.forename: Asanah
authors.initials: A
authors.lastname: Radhi
authors.forename: Kim Anh
authors.initials: KA
authors.lastname: Le
authors.forename: Michael E
authors.initials: ME
authors.lastname: Ries
authors.forename: Tatiana
authors.initials: T
authors.lastname: Budtova