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

Abstract

It is shown that an ionically charged L α -phase can be prepared without shear by mixing a small amount of methyl formate to a L 3 -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 L 3 - to the L α -phase. The resulting L α -phase is a low-viscosity classic L α -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 L α -phase is thermodynamically stable.