Liquid Crystalline State

Abstract

Liquid crystalline phases are formed by molecules of a specific, anisometric shape. The most typical are rod-like molecules or rod-like molecular aggregates, Fig. 1.1, which give rise to conventional nematic and smectic phases. Disc-like molecules form so-called columnar mesophases. Between these two types we can find lath-like molecules which do not possess the cylindrical symmetry. They can form optically biaxial nematic and, perhaps, smectic phases. However, in addition to those three types shown in Fig. 1.1(a–c) there are other, sometimes very exotic, molecular geometries which are also shown to be responsible for the formation of mesophases. Among them we can find swallow-tail, fasmidic, and bowlic molecules, the molecules consisting of flexible chains, Fig. 1.1(d–f), etc. Two special classes are presented by linear-chain and comb-like polymers, Fig. 1.1 (g, h), respectively. No doubt, in the near future, there will be synthesized novel molecules interacting with each other in a very specific way and giving rise to novel mesophases.