Liquid Crystals

Liquid crystals are an intermediate state (3-1) (Mesophase) described as a fourth state of matter. It was first called “flowing crystals” and “fluid crystals.” It appears between the solid phase, in which the movement of molecules is restricted in the triangular lattice. Dimensions and have an integrated molecular organization in location and direction, and the isotropic phase in which the molecules move freely and is considered to have a random organization, as in Figure (1-1). Liquid crystals are solid, linear, rod-like, or lamellar in shape. Although liquid crystals display certain properties that belong to the solid and liquid states, they possess special features that do not exist in both states (solid and liquid). The Austrian botanist Friedrich Reinitzer (4) in 1888 was the first to notice this state when he studied it. For cholesterol benzoate, it was found that this substance melts at a temperature of (146ºC), but it does not melt completely until it reaches a temperature of (179ºC), and in this intermediate state the substance is opaque.