Imidazolium-Based Ionic Liquids as Modulators of Physicochemical Properties and Nanostructures of CTAB in Aqueous Solution: The Effect of Alkyl Chain Length, Hydrogen Bonding Capacity, and Anion Type

The aggregation behavior of the cationic surfactant, cetyl trimethylammonium bromide (CTAB), in aqueous solution of various imidazolium-based ionic liquids (ILs) was investigated using tensiometry, conductometry, transmission electron microscopy (TEM), and cyclic voltammetry (CV) methods. The data obtained from tensiometry and conductometry measurments were used to specify the critical micelle concentrations (CMCs) and other physicochemical parameters. The CMC of the surfactant was found to significantly decrease in the presence of ILs. The surface activity parameters of CTAB were observed to be a function of structural properties of ILs. Furthermore, intermicellar interaction parameter (kd) was measured using cyclic voltametry. The intermicellar interaction parameter was also found to decrease slightly with addition of IL. However, in the presence of HMImBr or HMImCl, the intermicellar interaction parameter is not changed significantly, as a result of phase transition from spherical to cylindrical micell...