Chiral Lyotropic Liquid Crystals: TGB Phases and Helicoidal Structures

(Received 21 May 1996, received in final form 19 September 1996, accepted 26 September 1996)

Abstract
The molecules in lyotropic membranes are typically aligned with the surface normal. When these molecules are chiral, there is a tendency for the molecular direction to twist. These competing effects can reach a compromise by producing helicoidal defects in the membranes. Unlike thermotropic smectics, the centers of these defects are hollow and thus their energy cost comes from the line energy of an exposed lamellar surface. We describe both the twist-grain-boundary phase of chiral lamellar phases as well as the isolated helicoidal defects.