Liquid Crystals: General Introduction

We begin with the introduction of the subject of liquid crystals. It has come up of age and now is considered as a subject of a well-established and matured field of science. Liquid crystals are a state of matter sharing symmetry and properties that are usually associated with both anisotropic solids and isotropic liquids. Their study belongs to soft condensed matter physics, an area in which new physics are being discovered and various technological applications are being exploited. The purpose of present chapter is to introduce basic input background for the understanding of subsequent chapters. An overview of rheology, broad classification, known types of liquid crystals, some typical examples of mesogenic compounds together with observed phase sequences shown by them, a brief account of historical development, salient features of generic interaction models used to develop understanding about the behavior of liquid crystalline systems and the proper definition of order parameters are discussed.