Volumetric behaviour of 1-Butyl-3-Methyl imidazolium hexafluorophosphate with ethylene glycol derivatives: Application of Prigogine-Flory-Patterson theory

Abstract

Physical properties, such as densities, ρ, and refractive indices, n, for the binary mixtures of 1-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF 6] with ethylene glycol derivatives: diethylene glycol monomethyl ether (DEGMME); triethylene glycol monomethyl ether (TEGMME); triethylene glycol dimethyl ether (TEGDME); and tetraethylene glycol dimethyl ether (TetEGDME) have been measured over the whole composition range. Experimental densities were used to estimate excess molar volumes, V m E , apparent molar volumes, V ϕ, i , partial molar volumes, V̅ m,i , excess partial molar volumes, V̅ m,i E , and their limiting values at infinite dilution, V ϕ, i ∞, V̅ m,i ∞ , and V̅ m,i E,∞ respectively. Volumetric results have been analyzed in the light of Prigogine–Flory–Patterson (PFP) statistical mechanical theory. Interaction parameters have been calculated from V m E values for all the studied systems. The solute–solvent interactions have been investigated in terms of each of the three contributions viz. interactional, free volume and P ⁎ obtained from PFP theory at equimolar concentration. Deviations in refractive indices, Δ ϕ n have been calculated from experimental measurements of refractive indices . Excess properties are fitted to the Redlich-Kister polynomial equation to obtain the binary coefficients and the standard errors.