Liquid Crystals and Other Anisotropic Fluids

Abstract

This chapter deals with equilibrium properties of liquid crystals and other anisotropic fluids. After some remarks on nematic, cholesteric and smectic liquid crystals and blue phases, the second rank alignment tensor is introduced as the relevant order parameter for the nematic state. Theories for the phase transition isotropic-nematic are presented. The orientational elastic behavior of nematics and cholesterics is firstly described by the director elasticity involving the Frank coefficients and then by the alignment tensor elasticity theory. Systems with cubic and with tetrahedral symmetry, referred to as cubatics and tetradics, are characterized by fourth and third rank order parameter tensors. Some examples for the energetic coupling of order parameter tensors of equal and of different ranks are considered.