COMPARATIVE PHASE-BEHAVIOR ABOUT THE L-2-PHASE OF TERNARY AND QUATERNARY SYSTEMS OF TRITON-X-100 AND ITS SEPARATED P-TERT-OPEN (N=5, 7, AND9) COMPONENTS IN CYCLOHEXANE

The nonionic surfactant Triton X-100 (TX-100) is separated by preparat ive column chromatography into its poly(oxyethylene tert-octylphenyl e ther) (OPEn) components. The phase behavior in the neighborhood of the L-2 phase is investigated for ternary (cyclohexane/H2O) and quaternar y (cyclohexane/H2O/n-hexanol) systems of TX-100 and OPE, (n = 5, 7 and 9). The extent of the L-2 domain and the maximum amount of water omeg a(o,max) that can be solubilized by isotropic solutions strongly depen d on the concentration and the length (n) of the polar chain of the su rfactant, temperature, and the amount of n-hexanol present. Depending on these variables, with increasing omega(o) (molar ratio of water to surfactant) some of the following phase transitions occur: L-2 --> LC --> L --> liquid/gel --> gel. Except for the liquid crystalline LC pha se, all phases involved are optically isotropic, and the liquid L phas e is most likely bicontinuous. Since n-hexanol is a better solvent tha n cyclohexane for both the surfactant and water, it destabilizes the r everse micellar and LC assemblies. Hence, its effect on the systems in vestigated is more prominently that of a ''cosolvent'' than a cosurfac tant.