Chiral lyotropic liquid crystals

Abstract In this chapter the chiral mesophases of lyotropic mixtures are presented. We start with the cholesteric lyotropic liquid crystals, obtained by doping nematic mesophases with chiral molecules or using, directly, chiral amphiphilic molecules. In the framework of the Landau–de Gennes model, the free-energy density of the cholesteric phase, as a function of the temperature, is discussed. The relation between the cholesteric pitch and the concentration of chiral molecules in the lyotropic mixture is obtained from this model. Chiral lamellar mesophases, exhibiting twist-grain boundary phases, lyotropic blue phases, and the recently observed chiral lamellar structure, with its remarkable features, are also discussed.