Formation of highly swollen L_α-phases and vesicle phases form single chain surfactants by chemical reactions

摘要

Several general methods for the preparation of highly swollen lyotropic L_α-phases from single chain surfactants are described. It is shown that these L_α-phases can be prepared by mixing of surfactants with cosurfactants, by mixing of anionic and cationic surfactants, by combining ionic surfactants with hydrophobic counterions and surprisingly by mixing of Ca-salts of ionic surfactants with zwitterionic surfactants. Independently of their chemical composition the L_α-phases have several features in common: If the bilayers of the L_α-phases are ionically charged, and the phases are prepared by mixing of the components whereby the phases are exposed to shear forces, L_α-phases are obtained that have highly viscoelastic properties and consist of densely packed uni-and multilamellar vesicles. If, on the other hand, shear forces are avoided in the preparation, low viscous L_α-phases with stacked bilayers are obtained. Shear can be avoided when the phases are prepared with the help of a chemical reaction that produces one necessary component of the final phase in the stagnant fluid. Several reactions are described which can be used for the preparation of L_α-phases. It is shown that phase transformations to L_α-phases can be accomplished by the production of protons, of cosurfactants, or of ionic surfactants by chemical reactions. When the L_α-phases are produced by one of these reactions classic stacked bilayer phases are always obtained. These phases can easily be transformed to vesicle phases by exposing the L_α-phase to shear forces.