Polymer induced phase separation in lyotropic smectics

Abstract

Large water soluble macromolecules can be confined in all proportions into an electrostatically stabilized surfactant lamellar phase without change of the bilayer thickness. Upon progressive addition of salt, the sample phase separates into a polymer-rich and a surfactant-rich lamellar phase. Indeed, at some particular salt concentration, the intermembrane repulsive interaction is no longer sufficient to maintain the polymer coils squeezed into the lamellar structure. The phase separation is generally first order. But we could find a situation where it becomes second order.