Other Liquid Crystalline Systems

Abstract

In this chapter some rather different topics will be discussed. To begin with we will show that the possibilities for mesophase formation are not exhausted with nematic and smectic phases. In some compounds, liquid crystals with a cubic structure may be found. These cubic structures are rather rare in comparison to the other mesophases to be discussed here. Then in Sect. 4.2 mesophases consisting of disc-like molecules are discussed. This field of research is relatively young. Apart from a nematic phase, disc-like molecules may show several types of columnar phase (2D solid, 1D liquid). Polymers can often give liquid crystals, and form a field of increasing interest. In the third section of this chapter we shall summarize some basic information for the non-specialist, emphasizing similarities with mesophases of molecules of low molecular weight. Finally, we shall give some basic information about lyotropic liquid crystals. This state of matter consists of rod-like or disc-like molecules or aggregates of molecules in solution. Again we have to restrict ourselves strongly, and we refer to various other books for more detailed information.