Aggregation Behavior of Aqueous Solutions of 1‑Dodecyl-3-methylimidazolium Salts with Different Halide Anions

The interfacial and bulk properties of the aqueous solutions of imidazolium-based ionic liquids with different halide anions ([C12mim]­Cl, [C12mim]­Br, [C12mim]­I) were investigated by surface tension and electrical conductivity measurements. The lowest surface tension (γcmc) and maximum surface excess concentration (Γmax) values from the surface tension measurements showed that [C12mim]I had the highest surface activity. The thermodynamic pontentials of micellization (ΔG 0 m, ΔH 0 m, ΔS 0 m) indicated that the micellization of [C12mim]Cl and [C12mim]Br was entropy-driven, while that of [C12mim]I was enthalpy-driven at 15 °C but entropy-driven above 20 °C. This distinct behavior for [C12mim]I was thought to be due to the higher binding affinity of I– to the micellar interface.