Solubilization of polar oils in microemulsion systems

Abstract

A new type of amphiphile that contains both conventional surfactant and lipophilic linker features in a single molecule was designed and tested. In these so-called extended surfactants, a polypropylene oxide chain of variable length is inserted in between the conventional polar and apolar groups. With this type of surfactant, it was possible to produce for the first time a middle phase microemulsion in alcohol-free systems with long chain (C10–C18) synthetic and natural triglyceride oils. High molecular weight hydrocarbons were solubilized as well. The reported solubilization at optimum is found to depend upon both the propylene oxide chain length and the oil structure. The solubilization parameter of polar oils is found to attain quite remarkable values, in the range of several milliliters of oil per gram of extended surfactant, an interesting feature as far as the applications are concerned.