Extended surfactants containing an intermediatepolarity spacer, such as polypropylene oxide, in between the hydrophilic head and the hydrocarbon tail are known to result in superior solubilization and low interfacial tension, though they exhibit slow kinetics. The present work seeks to evaluate both equilibrium and kinetic aspects of extendedsurfactant-based micro-and macroemulsions. The interfacial morphology of the extended surfactant membrane, i.e., characteristic length (n) and interfacial rigidity (E r ) at optimum middle-phase microemulsion conditions, was characterized using the net-average curvature model. The results showed that extended surfactants resulted in a relatively rigid interfacial membrane compared with conventional surfactants having similar hydrocarbon chain length. In addition, both n and E r parameters increased with the length of the polypropylene oxide spacer. Increasing E r values correlated to the slow coalescence rates of extended surfactant emulsified systems. Two alternative approaches (the addition of combined linkers and co-surfactant) are shown to overcome the slow kinetics of coalescence while maintaining desirable high solubilization and low interfacial tension.

An aqueous surfactant-based extraction system was developed for the extraction of corn oil from corn germ with anionic extended surfactants. The surfactants used in this study were sodium linear-alkyl polypropoxylated polyethoxylated sulfates (C 12,

This work examined the use of a single extended surfactant in the microemulsion-based detergency of vegetable oils. The results showed that good canola oil detergency ([80%) was achieved at 25°C using a single extended surfactant (C 14,15 -8PO-SO 4 Na) at concentrations as low as 125 ppm, i.e., significantly lower than the surfactant concentration range of 500-2,500 ppm reported in other microemulsion-based detergency work. It was found that the maximum detergency (95%) was achieved in the type II microemulsion region. These results demonstrate that the microemulsion-based extended surfactant formulation is a promising approach for vegetable oil detergency at low temperature.

The effects of triglyceride molecular structure on the formulation of surfactant-oil-water systems were evaluated by comparing the optimum salinity and the dynamic interfacial tensions. The systems contained an anionic extended surfactant and triglyceride oils with different chain lengths and degrees of unsaturation. The results show that with an increasing degree of oil unsaturation (more double bonds), surfactant interactions with the triglycerides become weaker, thus requiring higher optimum salinity and resulting in higher interfacial tension values. Effects of ester groups and chain length of triglycerides are also discussed and the EACN of the triglycerides and vegetable oils studied are reported.

In this work, the impacts of extended surfactant structure (number of polypropylene oxide PO groups and branching nature of the hydrocarbon chain) on microemulsion formation and IFT values were examined with triglyceride oils. The results show that branching of the hydrocarbon tail of extended surfactants lowers optimum salinity and IFT values. The results also show that for the surfactants studied ultralow IFTs and microemulsion formation with vegetable oils can be achieved using extended surfactants with at least eight PO groups.