Chapter 3 - Sucrose Oleate Microemulsions

Abstract

Water/sucrose oleate+cosurfactant/oil microemulsions (MEs) were formulated for R (+)-limonene (LIM), isopropyl myristate (IPM), and caprylic-capric triglyceride (CCT) at 25°C, 37°C, and 45°C. The cosurfactants were ethanol (EtOH), propylene glycol (PG), glycerol (GLY), and propionic acid (PrA). The mixing ratios of sucrose oleate/cosurfactant equal unity and twofold. Increasing sucrose oleate/cosurfactant from unity to twofold does affect the maximum amount of solubilized water. Temperature-insensitive MEs were observed. The calculated free energy of solubilization decreases with the increase in the molecular volume of the oil and with the decrease in the amount of cosurfactant present in the system. Water+PG/sucrose oleate/oil MEs were also formulated at the same three temperatures. The oils were peppermint oil (MNT), LIM, α-ionone (ION), IPM, CCT, olive oil (OO), and sesame oil (SO). The areas of the one-phase ME region were determined. The area of the ME region depends on the oil type. Water+PG/sucrose oleate/glycerol monooleate/oil MEs were also formulated at the same three temperatures. The oils were MNT, LIM, ION, IPM, CCT, OO, and SO. An optimal amount of maximum solubilized water in the MEs was observed at a sucrose oleate/glycerol monooleate (GMO) mixing ratio equal to threefold. Water+PG/sucrose oleate/GMO/oil1/oil2 MEs were also formulated at the same three temperatures. The oils1 were MNT, LIM, and ION, while oils2 were IPM and CCT. An optimal amount of maximum solubilized water in the MEs was observed at an oil1/oil2 mixing ratio equal to unity. Water+PG/sucrose oleate/GMO/oil/cosurfactant MEs were also formulated at the three temperatures. The oils were IPM and CCT. The cosurfactants were EtOH, linalool, GLY, and PrA. An optimal amount of maximum solubilized water in the MEs was observed at an oil/cosurfactant mixing ratio equal to unity.