Random Surface Model for the L3-Phase of Dilute Surfactant Solutions

Abstract
We present a simple model for the anomalous (flow-birefringent) isotropic phase, known as L3, that is seen in certain surfactant solutions at volume fractions of a few percent. The proposed structure consists of locally sheetlike sections of semi-flexible surfactant bilayer, connected up at larger distances into a multiply connected random surface, having a preferred structural length scale of order the persistence length of the bilayer. A first-order transition between this isotropic sheetlike phase and the nearby swollen lamellar phase is described.