Properties of pure 1-(3-(trimethylammonio)prop-1-yl)-3-methylimidazolium bis(dicyanamide) asymmetrical gemini ionic liquid and its binary mixture with isopropanol at T = (283.15–333.15) K

Abstract

A novel asymmetrical gemini ionic liquid, 1-(3-(trimethylammonio)prop-1-yl)-3-methylimidazolium bis(dicyanamide) ([N111C3MIM][N(CN)2]2), was synthesized and characterized by 1H NMR, 13C NMR. Thermal stability of [N111C3MIM][N(CN)2]2 was investigated through thermogravimetric analysis under pure nitrogen atmosphere. Heat capacity of pure [N111C3MIM][N(CN)2]2 was measured using differential scanning calorimetry in the temperature range 298.15–423.15 K and enthalpy HT-H298.15K, and entropy ST-S298.15K were obtained. Densities and viscosities were measured for the binary system of [N111C3MIM][N(CN)2]2 and isopropanol (IPA) over the entire range of mole fractions at various temperatures from 283.15 to 333.15 K under the pressure of 0.101 MPa. Moreover, the excess molar volumes (VmE) and the viscosity deviations (Δη) for the binary mixtures were determined and well fitted to the Redlich−Kister polynomials. The negative values of VmE and Δη result from strong self-association and weak hydrogen bonding interaction between the molecules of [N111C3MIM][N(CN)2]2 and IPA. Excess Gibbs energy of activation (ΔG*E) of viscous flow for the present binary mixtures were also calculated. Results have been discussed in terms of molecular interactions and structures.