Polymer Confinement in Surfactant Bilayers of a Lyotropic Lamellar Phase

We report on small-angle x-ray scattering and free-fracture electron microscopy studies of a nonionic surfactant/water/polyelectrolyte system in the lamellar phase region. The surface tension data show that the polymer-surfactant interaction strongly depends on the polymer charge content. We demonstrate that regardless of the charge content the polymer molecules are confined inside the bilayers. The chains are collapsed into individual coils which are randomly spread in the bilayers. The polymer molecules cause both local deformation and softening of the bilayer.