Thermophysical properties of binary mixtures {1-methyl-3-pentylimidazolium tetrafluoroborate + polyethylene glycol methyl ether}

Abstract

Few reports are available on the thermophysical properties of ionic liquid (IL) and the polymeric (or oligomeric) solution binary system. In this study, the densities, viscosities, and refractive indices were determined for IL mixtures formed by 1-methyl-3-pentylimidazolium tetrafluoroborate [MPI][BF4] with polyethylene glycol methyl ether (MPEG) [Mw=350] over the mole fraction ranging from 0.1 to 0.9 and temperatures from 293.15 to 353.15K at intervals of 5K and atmospheric pressure. The temperature dependence of density and dynamic viscosity for both neat [MPI][BF4] and its binary mixtures were described by an empirical linear equation and by the Vogel–Tammann–Fulcher (VTF) equation, respectively. Excess molar volumes, viscosity deviations, and refractive index deviations were calculated from the experimental data and fitted to a Redlich–Kister polynomial function. The excess molar volume and viscosity deviations for the binary system were negative over both the composition and temperature ranges, whereas the refractive index deviations were always positive. The results have been interpreted in terms of ion–dipole interactions and the structural factors of the IL and MPEG molecular liquids.