Role of Oxygenated Oils in <i>n</i>-Alkyl β-<scp>d</scp>-Monoglucoside Microemulsion Phase Behavior

Abstract

The phase behavior of mixtures of water, alkyl ethylene glycol ethers (C k OC 2 OC k ) and n -alkyl β- d -glucopyranosides (C m G 1 ) is systematically reported as a function of temperature and composition. Previous work has shown that C m G 1 are nearly insoluble in alkanes, and ternary mixtures of water−alkane−C m G 1 produce stable emulsions. Replacing alkanes with more hydrophilic alkyl ethylene glycol ethers increases the solubility of C m G 1 in the oil. The well-known 2 −3−2̄ phase sequence is observed in water−C k OC 2 OC k −C m G 1 mixtures with increasing temperature, indicating that C m G 1 's partition into the oil at higher temperatures. This microemulsion phase behavior closely resembles that of mixtures made with water, oil, and other nonionic surfactants, e.g., n -alkyl polyglycol ethers (C i E j ), and both tricritical phenomena and general patterns of phase behavior are observed.