Thermodynamics Properties and Internal Interactions of Ether-Group Functionalized Thiocyanate Ionic Liquid 1-(2-Methoxyethyl)-3-Methylimidazolium Thiocyanate and Its Mixtures with 1,4-Butyrolactone or Propylene Carbonate

Abstract

In this paper, thermodynamic properties such as density, conductivity, and viscosity of an ether-based-functionalized ionic liquid (IL) 1-(2-methoxyethyl)-3-methylimidazole thiocyanate [MOEMIM][SCN] was measured at temperatures from (288.15 to 343.15) K and at atmospheric pressure (101 KPa). Then, the mixture systems blends of [MOEMIM][SCN] + 1,4-butyrolactone (GBL) or propylene carbonate (PC) were also prepared and measured over the whole composition range at the same temperature and pressure conditions. The Vogel–Fulcher–Tamman (VFT) equation was employed to describe the temperature dependence of transport properties (viscosity and conductivity). The Casteel–Amis four-parameter (C–A) equation was used to explain the mole fraction dependence of ILs on the electrical conductivity. From the experimental density and viscosity, the excess molar volume (VE) and viscosity deviation (Δη) were obtained, and fitting results of the Redlich–Kister (R–K) polynomial equation showed that the changes of the excess properties were reasonable for the mixtures. Combined with the COSMO–RS model based on DFT calculation, the intermolecular interaction situations of the mixture systems were evaluated. Further, the σ-profile can provide the computational aspect of specific interactions between molecules or between solvent through H-bond donors and H-bond acceptors.