PHYSIOCHEMICAL STUDIES OF MICROEMULSIONS

Viscosity and conductance of various microemulsion systems were studied over a range of temperature (30-80-degrees-C). The phase diagram of two systems studied were (I) alkane/Brij 35 (s)/water and (II) cyclohexane/NaDS(s)/water. n-Propanol was used as cosurfactant (cs) for both systems. The cs/s weight ratio was kept at 2. The nonane and heptane were used as alkanes in system I. The effect of NaCl on phase diagrams was found to be drastic at higher concentrations. For the nonionic Brij 35 systems, the effect of increase in temperature and increase in NaCl concentration were in the same direction. The conductance surprisingly decreases with increase in temperature for system II at very low w/o ratio. The Winsor transitons were also studied. The thermodynamic quantities for the solubilization of oil in water or water in oil for both systems at various surfactant concentrations were computed. All these are discussed here.