Preparation and Properties of Ionically Charged Lamellar Phases That Are Produced without Shearing

Abstract

It is shown that an ionically charged Lα-phase can be prepared without shear by mixing a small amount of methyl formate to a L3-phase from alkyldimethyl aminoxide, hexanol, and water. Within a few hours the methyl formate hydrolyzes to formic acid and methanol. The formic acid protonates the aminoxide surfactant head groups and triggers the transformation of the L3- to the Lα-phase. The resulting Lα-phase is a low-viscosity classic Lα-phase with stacked bilayers. By shearing or simply by shaking of a thus produced sample of low viscosity, it is transformed instantaneously into a highly viscoelastic phase with densely packed multilamellar vesicles. At present, it is not clear which form of the Lα-phase is thermodynamically stable.