Salt-solvent mixtures (SSMs): Investigation of physiochemical, thermodynamic and electrochemical properties of multifunctional imidazolium ionic liquids with DMSO

Abstract

Research on Ionic Liquids (ILs) recently focuses on investigating the properties of ILs salt-solvent mixtures (SSMs). The SSMs gained an unprecedented popularity because it offers wide range of properties necessary for the desired applications. In this work, imidazolium ILs containing nitrile and varying number of ether group coupled with bis(trifluoromethanesulfonyl)imide anion were synthesized. These ILs were mixed with dimethylsulfoxide (DMSO) in various mole ratio to form a salt-solvent mixtures. Density, dynamic viscosity and electrical properties of pure ILs and its mixtures were investigated over a wide temperature range. Thermodynamic properties such as thermal coefficient of expansion, standard entropy and lattice energy of pure ILs increased when the number of ether group on the cation side chain increased. Dynamic viscosities and electrical conductivity of the SSMs were investigated over a wide temperature range and different mole ratio, described by Vogel–Fulcher–Tamman (VFT) equation and Arrhenius equation. The relationship between dynamic viscosity and electrical conductivity was illustrated by Walden's Rule and it revealed that the SSM's have high conductivities at low fluidity, which can be categorized as ‘super ionic liquids’. Electrochemical potential window (EPW) and conductivity results for the SSMs revealed their (Mole ratio ILs =0.8) excellent potential in electrochemical applications.