triangle in whole phase equilibria, we can calculate the mo-Microemulsions are formed over a wide range of temperatures nomeric solubility of oil-soluble surfactant in oil and the in brine / sodium dodecyl sulfate / polyoxyethylene dodecyl ether mixing fraction of the surfactant in surfactant layer inside (C 12 EO 2 or C 12 EO 3 )/ decane systems. In a dilute region, lamellar the microemulsion (7). According to the former result, it is liquid crystal is present instead of bicontinuous microemulsion very important to use a lipophilic cosurfactant whose solubilat the composition at which the HLB of the mixed surfactant is ity in oil is very small. In this sense, the combination of optimum in the given system. The monomeric solubilities of ionic and nonionic surfactants is very good candidate for C 12 EO 2 or C 12 EO 3 in oil and the mixing fraction of C 12 EO 2 or temperature-insensitive microemulsions.
C 12 EO 3 in the mixed surfactant layer were determined using the Recently, however, it is reported that middle-phase migeometrical relation of three-phase tie triangle containing the liquid crystal phase in the composition tetrahedron and were croemulsions are not formed in a SDS-polyoxyethylene docompared at 35 and 60ЊC. The change in the HLB composition decyl ether system (8). Due to the strong interaction bewith temperature is well described by increasing the monomeric tween both surfactants, lamellar liquid crystal intrudes into solubility and decreasing the mixing fraction of nonionic surfacmicroemulsions and the liquid crystal phase exists in a dilute tant in the surfactant layer. As a result, temperature-insensitive regions when the mixed surfactant is in a balanced state. In microemulsions are formed in the SDS -C 12 EO 3 system. ᭧ 1997 the dilute regions, the liquid crystal phase coexists with water Academic Press and oil phases and the same geometrical relation as that