Study on the phase diagrams of aqueous two-phase and microstructure of cationic-anionic mixed surfactants

The aqueous two-phase regions and the relevant properties of water/sodium d odecyl sulfonate (SDS)/cetyl trimethyl amine bromine(CTAB) system have been determined. It is shown that there are two aqueous two-phase in two region s with excess SDS or CTAB. The one with excess SDS has cloud point. Obvious phenomena of polarized light can be detected in the upper phase. Another a queous two-phase region with excess CTAB has the property of Krafft point a nd the phenomena of polarized light isn't remarkable in the upper phase. Th e freezing etch TEM photograph showed that the structure of upper phase is lamellar and the lower phase is sphere-like. The volume ratio of two phases is sensitive to minor variations of the ratio between anionic surfactant a nd cationic surfactant.