Catanionic surfactant formation from the interaction of the cationic surfactant hexadecyltrimethylammonium bromide ( CTAB ) and the ionic liquid 1butyl3methylimidazolium 1butyl3methylimidazolium 1butyl3methylimidazolium butyl3methylimidazolium butyl3methylimidazolium 3methylimidazolium 3methylimidaz

The interaction between the cationic surfactant Hexadecyltrimethylammonium bromide (CTAB) and the ionic liquid 1-butyl-3-methylimidazolium octyl sulfate (bmim-octylSO4) in aqueous solution has been investigated at two total concentrations (0.5 and 10 mM) and different CTAB mole fractions (CTAB). Samples of different physical appearance were obtained depending on CTAB suggesting different kind of aggregates. Bluish solutions (CTAB from 0.1 to 0.6) were assigned to vesicles of the catanionic surfactant formed (CTA-octylSO4), whereas clear and isotropic solutions (CTAB  0.6) corresponded to mixed micelles. Surface tension, electrical conductivity, absorbance and dynamic light scattering (DLS) measurements were performed with the aim of correlating properties changes with the aggregation structures. The critical aggregation concentration (cac) and the surface tension value at the cac (cac) were much lower for the mixtures than for the individual components. Thiis finding reveals the