Spontaneous Formation of Vesicular Structures from a Swollen Lamellar Phase by Dilution and Control of Surface Charge Density

Abstract

Over the past several years there has been increased interest in the phase behavior and morphology of the dilute region of amphiphilic systems. A general sequence of phases has been shown to exist when a single variable is changed, such as alcohol, salinity or temperature of an amphiphilic surfactant solution. The surfactant can be anionic, cationic, zwitterionic or nonionic. The sequence of phase transformations represents a spontaneous change in the curvature and self — association of the amphiphile whereby an isotopic micellar solution transforms into a highly swollen homogeneous lamellar phase made up of sheets of bilayers, to an optically isotropic phase which scatters light and exhibits birefringence when sheared (1). These phases are designated L₁, L _α and L₃ respectively.