Abstract: The formation and stability of vesicles from the mixture of cationic cetyltrimethylammoniium bromide (CTAB) and anionic surfactant were investigated. The three different anionic surfactants were sodium dodecylbenzenesulfonate (SDBS), sodium dodecyl sulfonate (SDS) and sodium dodecyl sulfate (SLS) respectively. Vesicles all can form in systems cationic and each of three anionic (cationanionic) surfactants. The experimental results show that although three anionic surfactants have similar molecular structure, the mixed ratio of catanionic surfactant with each anionic surfactant was entirely different for the formation of vesicles. The stabilities of vesicles were different either. The present paper discusses the formation of vesicles according to the physical properties of surfactants and investigates the stability of vesicles. The TEM technique was used to observe the shape of vesicles.

Key words: cationanionic surfactant, vesicle, stability