Highly Curved Defects in Lyotropic Lamellar Phases

Lamellar phases of non ionic surfactant/water systems were investigated by two different experimental methods: (i) Spin labelling, which revealed the existence of highly curved defects, precursors of the high temperature phase, whose concentratin increased with temperature. (ii) Electron microscopy of replicas of freeze-fractured samples which showed the existence of screw dislocations, whose concentration increased with temperature. These screws are the components of dislocation loops crossing the layers. Parts of the highly curved areas indicated by ESR are attributed to the cores of these dislocations.