Abstract:

A study was made of the characteristics of microemulsions composed of sucrose monostearate (SMS), medium-chain triglycerides (MCT), or R-(+)-limonene, alcs., and water. The systems are homogeneous, soft, and waxy solids at room temp. but liquefy and structure into homogeneous microemulsions when heated to \textgreater40 °C. The amt. of solubilized water is enhanced as a function of the alc./oil ratio and is inversely proportional to the alc. chain length. Over 60 wt% water can be solubilized in systems consisting of propanol/MCT/SMS at a wt. ratio of 3:1:4 (initial wt. ratio). These microemulsions are unique and differ from nonionic ethoxylated-based microemulsions in that their viscosity is very low and is reduced with increasing amts. of solubilized water. The elec. cond. increases only slightly as a function of the water content and does not show typical bicontinuous or percolated behavior. The water in the core of the microemulsion strongly binds to the headgroups of the surfactant. Only at \textgreater15 wt% solubilization of water was free or bulk water detected in the core of the microemulsions. Such unique behavior of the core water might have a possible application in systems requiring monitoring of enzymic (lipase) reactions carried out in the microemulsions as microreactors. [on SciFinder(R)]