Calamitic mesophases cholesteric

Discotic liquid crystals arise from disc-shaped molecules as nematic or cholesteric mesophases. Their structural characteristics are similar to that of their respective calamitic mesophases, that is, the normals... 

Figure 6.1 Schematic representation for some different mesophases formed by calamitic meso-gens. P/2 is half of cholesteric pitch.

FriedeP was the first who distinguished three main classes of liquid crystals, according to the different kind of orders in the mesophases nematic, smectic, and cholesteric. From the point of view of the geometrical shape of molecules, we divide the thermotropic LCs into calamitic phases (when the molecules are rodlike), sanidic phases (when the molecules are bricklike), and the discotic phases (when the molecules are disklike)... 

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