The importance of lipophobicity in surfactants: methods for measuring lipophobicity and its effect on the properties of two types of nonionic surfactant.
In researching the properties of surfactants, lipophobicity is an important consideration. Increasing surfactant lipophobicity corresponds to a decrease in the saturation concentration of a singly dispersed surfactant in oil, i.e., a decrease in the critical micelle concentration in oil (CMC(oil)). This, in turn, is the crucial property in discussing the efficiency of a surfactant. Lipophobicity is influenced by the structure and length of the hydrophilic moiety of the surfactant. Surfactants that consist of OH or CO groups are effective for use in both aliphatic and aromatic hydrocarbon-rich systems because they are highly lipophobic and of a compact size and function independent of temperature. These characteristics are also reflected in their phase behavior. Phase diagrams illustrate the following properties: temperature independence; strong absorption at the water-oil interface and efficient action even with a very small amount of surfactant with a low CMC; high solubilization of water and oil into an aggregated surfactant solution phase. Through phase diagrams, the CMC(oil) of R10EO8 was obtained and the result used to compare the many different characteristics of the more typical oxyethylene nonionic surfactants with the new polyglyceryl nonionic surfactants.
Fukuda
Morinobu
M
Tokyo Research Laboratories, Kao Corporation Bunka 2-chome 1-3, Sumida-ku, Tokyo 131-8501, Japan. fukuda.morinobu@kao.co.jp