Studies in the phase behavior of the microemulsions formed by mixed cationic and nonionic surfactants

The middle-phase behavior for the systems of cetyltrimethylammonium bromide (CTAB)/poly-ethyleneglycol-9-monododecyl ether (AEO9)/alcohol/oil/brine and CTAB/octylphenolpolyoxyethylene-10-ether (Triton X-100)/alcohol/oil/brine have been studied with ɛ-β fishlike phase diagram method. The interfacial layer composition was determined, and some significant physicochemical parameters are derived from the hydrophilic-lipophilic balance plane equation. The effects of different alcohols, oils, temperature and inorganic salt (NaCl) on the middle-phase behavior of microemulsion formed by composite CTAB/AEO9 systems were also investigated systematically. The effects of different factors on the phase behavior of microemulsions formed by CTAB/AEO9 and CTAB/TX-100 systems were compared. The results suggest that the solubilization of CTAB/AEO9 microemulsion is higher than that of CTAB/TX-100 system under the same conditions.