Spontaneous Vesicle Phase Formation by Linear Pseudo-Oligomeric Surfactant in Aqueous Solutions

In the present work, we reported a novel linear pseudo-oligomeric surfactant, which is formed by mixing dodecyl benzenesulfonate (SDBS) and a linear tricationic imidazolium bromide salt (LTIB) in a molar ratio of 3:1. The aggregation behavior, aggregate structures, and interactions between SDBS and LTIB were investigated by surface tension measurement, dynamic light scattering, turbidity, cryogenic transmission electron microscopy, and 1H NMR techniques. When SDBS is mixed with LTIB in aqueous solutions, three SDBS molecules may be “bridged” to one cationic LTIB molecule by intermolecular interactions, behaving like a linear oligomeric surfactant. Vesicles can be formed by this kind of linear pseudo-oligomeric surfactant. The aggregation behavior of the LTIB/SDBS mixed aqueous solutions behaves ratio- and concentration- dependence. Our work paves a convenient way for constructing surfactant systems with the characteristics of linear pseudo-oligomeric surfactant through intermolecular interactions between commercially available single-chain surfactants and linear tricationic imidazolium counterions.