Electrical conductivity and refractive index of binary ionic liquid mixtures with diethyl carbonate, dimethyl carbonate and propylene carbonate

Four imidazolium-type ionic liquids (ILs) [Emim][NTf2], [Emmim][NTf2], [Bmim][NTf2] and [Bmmim] [NTf2] have been synthesized and used to prepare binary mixtures with organic solvents dimethyl carbonate (DMC), Diethyl carbonate (DEC), and propylene carbonate (PC), respectively. The electrical conductivity and refractive index of the mixtures were measured and discussed from 293.15 to 323.15 K. The dependence of electrical conductivities of the binary mixtures on the concentration of mole fraction and temperature were fitted from the empirical Casteel-Amis (CA) equation and Vogel-Fulcher-Tamman (VFT) equation, respectively. The maximal conductivities were discussed from the fitted values for the ILs with different solvents. The dependence of refractive indexes of the binary mixtures on the concentration of mole fraction and temperature were also fitted from the Redlich-Kister polynomial equation and linear equation. Moreover, the influences of introducing methylene and methyl into the cation of ILs on their properties are discussed.