Liquid Crystal Mesophases
Everyday experience has led to universal familiarity with substances that undergo a single transition from the solid to the isotropic liquid phase. The melting of ice at 0°C to form liquid water is perhaps the most common such phase transition. There are, however, many organic materials that exhibit more than a single transition in passing from solid to liquid, thereby necessitating the existence of one or more intermediate phases. It is not surprising that the molecular ordering in these intermediate phases, known as “mesophases”, lies between that of a solid and that of an isotropic liquid. The partial ordering of the molecules in a given mesophase may be either translational or rotational, or both. Clearly, translational order can be realized regardless of molecular shape, whereas rotational order has meaning only when the constituent molecules are nonspherical (elongated). Thus, there is good reason to expect molecular structure to be an important factor in determining the kind and extent of ordering in any particular mesophase.
KeywordsLiquid Crystal Nematic Liquid Crystal Plastic Crystal Nematic Phase Cholesteric Liquid Crystal
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