Middle-Phase Microemulsions Formed by n-Dodecyl Polyglucoside and Lauric-N-methylglucamide

Abstract

The three-phase behaviors for the quaternary system of n-dodecyl polyglucoside or lauric-N-methylglucamide (MEGA-12)/n-alcohol/alkane/water have been studied with ϵ-β fishlike phase diagram. The increase of ϵ at constant β causes a series of phase inversions Winsor I(2) → III(3) → II . The physicochemical parameters, such as the mass fraction of n-butanol in the hydrophile-lipophile balanced interfacial layer (AS), the coordinates of the start and end points of the middle-phase microemulsion, and the solubilities of surfactant and n-butanol in alkane phase were calculated. The effects of different oils and aqueous media on the phase behavior, the composition of the interfacial layer, and the solubilizing power were investigated. It was found that the oil with small molecular volume increases the solubilizing power. In inorganic salt (NaCl) and acid (HCl) solutions, less n-butanol is needed than that in alkali (NaOH) solution to form middle- and single-phase microemulsions. The middle-phase microemulsions formed by n-dodecyl polyglucoside and lauric-N-methylglucamide were compared.