Thermotropic mesophases and mesophase transitions of linear, flexible macromolecules

Abstract

The field of mesophases is subdivided into six different phases: liquid crystals, plastic crystals, condis crystals and the corresponding LC, PC, and CD glasses. Liquid and plastic crystals are the traditional phases with positional and orientational disorder, respectively. Condis crystals are conformationally disordered. On hand of tables of thermodynamic transition parameters of small and large molecules it is shown that the orientational order in liquid crystals is only a few per cent of the total possible, while the positional order in plastic crystals is virtually complete. Condis crystals have a wide variety of different degrees of conformational disorder. The glass transitions of all mesophases are similar in type. Macromolecules in the liquid crystalline state produce high orientation on deformation. Plastic crystals consist always of small molecules. Condis crystals may under proper conditions anneal to extended chain crystals.