Studies of Formation and Interface of Oil-Water Microemulsion

Hung-Jang Gi；Shou-Nan Chen；Jenn-Shyong Hwang；C. Tien；M. T. Kuo

Chinese Journal of Physics

30卷5期（1992 / 10 / 01）

665 - 678

英文

Oil-in-water microemulsions were prepared by the titration method. A mixture of fatty acid and oil was added to a caustic solution to produce a microemulsion, which was then titrated with a cosurfactant, an alcohol, until the system turned clear. It was found that as the chain length of the surfactant increased, microemulsions with significant transmittances by visible spectrum could be formed with oils of longer chain lengths. It was also found that different alcohols affected the formation of microemulsions in different ways. The best results, in terms of the greatest percent transmittance coupled with the widest range of oil (dispersed in water) concentration, were obtained from short or branched alcohols.The properties of the transparent system, n-cyclohexadecanone/margaric acid/4-methylcyclohexanol (4-methyl-1-pentanol)/water was investigated by photon correlation spectroscopy. Droplet sizes varied from 14 nm to 46 nm in diameter, and the surfactant cross-sectional area was calculated to be approximately 0.017 nm^2 to 0.029 nm^2 per molecule. This implied that surfactant molecules at the interface were incorporated by the cosurfactant molecules.