Complete unbinding and quasi-long-range order in lamellar phases

Abstract

Lamellar phases of lyotropic liquid crystals can be swollen by addition of solvent. Such a process, which leads to a strong increase of the mean interlamellar separation l¯, can be viewed as a phase transition, termed complete unbinding. Starting from the microscopic interaction for a pair of lamellae, we derive an effective model for the multilayer phase. We predict a power-law increase of l¯, and show that the system exhibits quasi-long-range translational order characterized by an exponent $X_m$, which is either universal or, for sufficiently long-range repulsive interactions, depends on molecular details.