Topological defects in lamellar phases: passages, and their fluctuations

(Received 4 March 1993, accepted in final form 23 March 1993)

Abstract
In lamellar phases of ternary amphiphilic mixtures, passages are tube-like connections of neighboring oil- (or water-) layers. Passages form spontaneously due to the thermal fluctuations of the monolayers (or membranes), which separate oil and water. Analogous membrane conformations also exist in binary amphiphilic mixtures, where the membranes are amphiphilic bilayers. We study the shape and the fluctuations of passages. Our analysis is based on the curvature model of fluid membranes, both with and without spontaneous curvature. Passages have a very small bending energy, and show strong fluctuations. The mean radius, the fluctuations of the radius, and the asphericity of the passage are calculated. All these quantities are experimentally accessible.