Liquid Crystal

Name:
Liquid Crystal
Detailed information:
An organic compound in an intermediate or mesomorphic state between solid and liquid. This phenomenon was first noted in 1888 in cholesteryl benzoate, a crystalline solid. It becomes a turbid liquid, or liquid crystals, when heated to 145C; on further heating to 179C the liquid becomes isotropic. This sequence is reversed when the substance is cooled. Color changes occur on both heating and cooling. Many organic compounds, e.g., sodium benzoate, exhibiting this behavior are known and used extensively in electric and electronic displays, thermometers, color TV tubes, electronic clocks and calculators, and similar devices dependent on temperature determination. Liquid crystals have several varieties of molecular order: nematic, smectic (nine types), and cholesteric. They indicate small temperature differences by changing color when applied to the skin and are used in medicine for this purpose. They can align with dichroic dye molecules in a thin-layer cell to produce color changes.

Available Forms:

Microencapsulated.

See Nematic; Smectic; Cholesteric.