Microemulsions of triglyceride and non-ionic surfactant — effect of temperature and aqueous phase composition

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 1993-12, Vol.80 (2), p.153-160
• Main Authors: Joubran, Remon F., Cornell, Donald G., Parris, Nicholas
• Format: Article
• Language: English
• Subjects: Aqueous phase composition; Chemistry; Colloidal state and disperse state; Emulsions. Microemulsions. Foams; Exact sciences and technology; General and physical chemistry; Microemulsions; Non-ionic surfactant; Temperature; Triglyceride
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/0927-7757(93)80194-J

The phase behavior of soybean oil, polyoxyethylene (40) sorbitol hexaoleate and water—ethanol was investigated. Regions of water-in-oil (W/O) microemulsions were determined and were found to be strongly dependent on temperature and water:alcohol ratios. At a water:ethanol ratio of 80/20 (wt.%), an oil:surfactant ratio of 2/3 and a temperature of 25°C, the microemulsion region extended continuously from the oil—surfactant axis to the phase diagram center. However, at the hydrophilic—lipophilic balance (HLB) temperature (20–22°C) and a water:ethanol ratio of 80/20 or 75/25 (wt.%), a single-phase area separated from the original microemulsion region. Conductivity measurements and dynamic light scattering intensifies at 25°C indicated that association structures were formed with increasing aqueous phase concentrations above 15 wt.%. At 20°C, the single-phase scattering intensifies increased sharply with increasing aqueous phase concentrations (38–46 wt.%) and a plateau in the conductivity was detected. Transmission electron microscopy results supported the finding that more particles are formed with increasing aqueous phase and form connected particles, resulting in constant conductance.