Study on the properties of density, viscosity, excess molar volume, and viscosity deviation of [C2mim][NTf2], [C2mmim][NTf2], [C4mim][NTf2], and [C4mmim][NTf2] with PC binary mixtures

Abstract

The imidazolium type ionic liquids (ILs) 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ([C2mim][NTf2] and [C4mim][NTf2]) were synthesized. For comparing, the ILs with introduction of methyl group 1-alkyl-2,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C2mmim][NTf2] and [C4mmim][NTf2]) were also prepared. The density and viscosity of the systems composed of above ILs and propylene carbonate (PC) were determined. The determined uncertainties are u(ρ) = 0.00010 g·cm−3 for density and ur(η) = 0.02 for viscosity, respectively. The excess molar volumes, thermal expansion coefficients, viscosity deviations, and a-constant were calculated. According to Redlich−Kister equation, the relationship between excess molar volume, viscosity deviation and mole fraction was fitted. By comparing with the systems of the same ILs in other organic solvents, the above-mentioned properties were discussed and the influence of introduced methylene group and methyl group on the above properties was analyzed.