Recent Advances in Catanionic Mixtures

Most surfactant mixtures display synergistic physicochemical properties, which have led to their extensive application in various technologies. Aqueous mixtures of two oppositely charged surfactants, so‐called catanionic surfactant mixtures, exhibit the strongest synergistic effect, which is manifested as high surface activity, enhanced adsorption and a low critical aggregation concentration. In addition, catanionic systems display rich phase behavior and a range of nano and microstructures, including small spherical micelles, rod‐like micelles as well as open and closed bilayers (vesicles). The spontaneous formation of catanionic vesicles is of special interest due to their various applications in nanotechnology and pharmaceutical formulations. In this chapter, the properties of catanionic mixtures of amphiphilic molecules with advantageous properties are discussed. Since numerous papers dealing with catanionic mixtures of monomeric surfactants already exist, the aim of this chapter is to summarize recent progress in mixtures of structurally different surfactants. At the end of the chapter, special emphasis is placed on applications of catanionic mixtures.