What causes the low viscosity of ether-functionalized ionic liquids? Its dependence on the increase of free volume

Cholesteryl-containing ionic liquid crystals composed of alkylimidazolium cations and different anions

“…All these imidazolium-based materials including the imidazolium chloride salts and the imidazolium tetrachloroaluminates displayed the same order of magnitudes of ionic conductivities in mesophase, but the conductivity in isotropic phase was a magnitude greater or more than that in mesophase due to decrease of viscosity [48]. In comparison with the imidazolium chloride salts, the imidazolium tetrachloroaluminates presented a higher conductivity increase both in mesophase and in isotropic phase due to stronger interaction among AlCl 4 À and imidazolium cations, although very little difference in conductivity was observed in the imidazolium-based salts with the same anions.…”

Acyclic and Cyclic Alkyl and Ether‐Functionalised Sulfonium Ionic Liquids Based on the [TFSI]− and [FSI]− Anions as Potential Electrolytes for Electrochemical Applications

“…Ruiz et al demonstrated that the conductivity of 1-butyl-1-methylpyrrolidinium bis{(trifluoromethyl)sulfonyl}imide ([Pyrr 14 ][TFSI]) could be increased significantly from 2.5 mS · cm À1 to 45 mS · cm À1 at 25 8C by mixing the IL with acetonitrile. [11] The substitution of alkyl groups with a similarly sized, flexible ether group onto the cation structure has been shown previously to reduce the viscosity of the IL. [11] The substitution of alkyl groups with a similarly sized, flexible ether group onto the cation structure has been shown previously to reduce the viscosity of the IL.…”

“…This trend is observable in imidazolium, [45] ammonium, [46] sulfonium, [25] phosphonium, [47] and pyrazolium [15] ILs reported in the literature. These reduction in viscosities may be attributed to the increased flexibility of the cation chain, [11,12] or a reduction in inter-cationic association of the ethereal groups relative to the similarly sized alkyl groups. [46] Increasing the length of the alkyl chain (i. there is a balance on the resulting IL transport properties between the relative increase in cation size (molecular weight) and the promotional effects of introducing higher degrees of ether functionality.…”

Ionic Liquids and their Polymers in Lithium‐Sulfur Batteries

“…Replacing an alkyl chain by an alkoxy chain in the IL cation shows a significant effect on the electrolyte viscosity (η) (Table ). Zheng et al . measured these to be highly variable and strongly dependent on the structures of the cation and ether moiety.…”