Synthesis, Characterization, and Properties of Ether-Functionalized 1,3-Dialkylimidazolium Ionic Liquids

A family of new ether-functionalized ionic liquids based on 1,3-dialkylimidazolium cation with alkoxymethyl or alkoxyethyl group and TFSA anion were synthesized and characterized. The properties of these ionic liquids, including melting point, thermal stability, density, viscosity, conductivity, and electrochemical window, were determined and compared with those of 3 typical 1,3-dialkylimidazolium ionic liquids without ether group. The effect of ether group on the properties was systematically investigated. All these ionic liquids were liquid at room temperature, and their melting points were lower than −60 °C. It was demonstrated that alkoxyethyl group was favorable to decreasing viscosity of 1,3-dialkylimidazolium ionic liquids, and alkoxymethyl group was not helpful for decreasing viscosity. At room temperature, 6 new ionic liquids had the viscosities lower than 45 cP, and the viscosity of IM2o2-2-TFSA was only 31.3 cP.