CHIRAL LYOTROPIC LIQUID-CRYSTALS - TGB PHASES AND HELICOIDAL STRUCTURES

The molecules in lyotropic membranes are typically aligned with the su rface 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 t hermotropic smectics, the centers of these defects are hollow and thus their energy cost comes from the line energy of an exposed lamellar s urface. We describe both the twist-grain-boundary phase of chiral lame llar phases as well as the isolated helicoidal defects.