Room-Temperature Ionic Liquid-Organic Solvent Mixtures: Conductivity and Ionic Association

Abstract

Ion-transport properties of room-temperature ionic liquids (RTILs), N, N-diethyl-N-methoxyethyl-N-methyl ammonium (DEME) with different anions, BF₄ and (CF₃SO₂)₂N, as well as their mixed systems with two different organic solvents, propylene carbonate (PC) and 1,2-dichloroethane (DCE), have been explored by means of conductometry and pulsed-field-gradient spin-echo (PGSE) NMR diffusivity measurements. In a highly concentrated range from the neat ionic liquids to 1 mol dm⁻³ solution, an increase in the organic solvent content contributes to an increase in the ionic diffusion coefficients, which is reflected in enhancement of the ionic conductivity. Such increase in the solvent content, on the other hand, promotes the ionic association, even if highly polar PC is introduced as the solvent.