Answer to Question #110612 in Inorganic Chemistry for Ravi

Question

What are liquid crystals? Explain their different types.

Answer 1

Liquid crystal is a term referring to substances that are not crystalline (solid) nor isotropic (liquid), but somewhere between the two. For example, many proteins and cell membranes are liquid crystals. There are three main types of liquid crystals, or what is scientifically known as mesophases:

1. The nematic phase is the simplest form of liquid crystal and is the phase in which the crystal molecules have no orderly position and are free to move any which way. However, while they have no specific order, during this phase the molecules do tend to point in the same direction, which is what differentiates it from a pure liquid.
2. The smectic phase of liquid crystal is characterized by a slight degree of translational order in the crystal molecules which is not found in the nematic phase.
3. The cholesteric phase, also known as chiral nematic phase, is characterized by the molecules being aligned and at a slight angle to one another, stacked within very thin layers– it is the last phase before a substance becomes crystalline, or solid. This type of liquid crystal also has the characteristic of changing color when it is exposed to different temperatures.