Solubilization of polar oils with extended surfactants

Abstract

Starting with previous results showing that the solubilization of oil and water in a microemulsion can be improved by the introduction of an additive, i.e. a so-called lipophilic linker, a new surfactant type that mimics the additive effect is tested. The so-called extended surfactant has a poly-propylene oxide chain inserted in between the conventional alkyl and ether sulfate groups. These surfactants exhibit a critical micelle concentration and a cloud point that changes with the number of propylene oxide groups per molecule (ranging from 6 to 14). They show three-phase behavior at optimum formulation, with hexadecane, ethyl oleate, and, as reported for the first time, with triglyceride oils, such as soya oil. Outstanding values of the optimum solubilization parameter are reached (in the 10–30 ml g −1 range).