Thermophysical properties of a room temperature ionic liquid (1-methyl-3-pentyl-imidazolium hexafluorophosphate) with poly(ethylene glycol)

Physical properties such as density, ρ, viscosity, η, refractive index, n, and conductivity, κ, for the binary mixtures of 1-methyl-3-pentyl-imidazolium hexafluorophosphate [MPI][PF6] with poly(ethylene glycol) (PEG) [Mw = 200] are measured over the whole composition range. The excess molar volumes, VE, are calculated using the measured experimental densities and correlated using the Redlich–Kister type equation. The correlation results are in agreement with the experimental data, and optimal fitting parameters are present. All the VE values within the tested range are negative, and continue to become increasingly negative with increasing temperature. The coefficients of thermal expansion are calculated from the experimental density results using an empirical correlation for T = 293.15–353.15 K. Deviations in viscosity, Δη and the refractive index, Δϕn, are calculated from experimental measurements of viscosity, η and refractive index, n, respectively and are fitted using the Redlich–Kister polynomial equation to obtain the binary coefficients and the standard deviations.