2000 Volume 73 Issue 6 Pages 275-281
The effect of oil components on the lowering of oil/water interfacial tension in the presence of nonionic surfactants (polyoxyethylene (n) oleylether, n = 10, 20) was investigated. The oil/water interfacial tension was strongly dependent on the combination of two oils. The combination of nonpolar squalane and polar oleic acid gave the minimum interfacial tension, resulting in the spontaneous emulsification in the vicinity of the oil/water interface. Near-infrared spectroscopy revealed that the concentration of oleic acid monomer in the oil mixture with squalane was higher than that in the mixture with other oils such as methyl oleate at lower oleic acid fractions. Thus, reduction of interfacial tension between oleic acid-squalane mixed oil and water was considered to be due to the effective orientation of oleic acid monomer at the oil/water interface.
