About Liquid Crystals
The Liquid-crystalline State - Molecular Shape and Structure and Liquid Crystals - Thermotropic Liquid Crystals - Lyotropic Liquid Crystals - Plastic Crystals - Structures of Thermotropic Liquid Crystals - Structures of Smectic Liquid Crystals
Plastic Crystals
Plastic crystals are not usually incorporated into descriptions of mesogens, however, they are very closely related and therefore worthy of discussion in relation to liquid crystals. Plastic crystals usually possess molecules that have spherical shapes, see figure, and like the soft crystals associated with liquid crystal systems, the molecules in plastic crystals have long range periodic order and rotate very rapidly about their lattice points. The molecular motion is diffuse and takes place in all directions, unlike the process in liquid crystals which is principally about one major axis. Plastic crystals, therefore, are optically isotropic.
The Liquid-crystalline State - Molecular Shape and Structure and Liquid Crystals - Thermotropic Liquid Crystals - Lyotropic Liquid Crystals - Plastic Crystals - Structures of Thermotropic Liquid Crystals - Structures of Smectic Liquid Crystals