Search results
Results from the WOW.Com Content Network
Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals.For example, a liquid crystal can flow like a liquid, but its molecules may be oriented in a common direction as in a solid.
For example, 5CB — a classic example of an achiral nematic thermotropic LC — undergoes an isotropic-nematic transition at 308K and a nematic-crystalline transition at 252K. [14] Similarly, poly(n-hexyl isocyanate), a lyotropic liquid crystal, undergoes the analogous isotropic-nematic transition at weight fractions ranging from 0.225 to 0. ...
4-Cyano-4'-pentylbiphenyl is a commonly used nematic liquid crystal with the chemical formula C 18 H 19 N. It frequently goes by the common name 5CB. 5CB was first synthesized by George William Gray, Ken Harrison, and J.A. Nash at the University of Hull in 1972 and at the time it was the first member of the cyanobiphenyls.
Liquid crystal states have properties intermediate between mobile liquids and ordered solids. Generally, they are able to flow like a liquid, but exhibiting long-range order. For example, the nematic phase consists of long rod-like molecules such as para-azoxyanisole, which is nematic in the temperature range 118–136 °C (244–277 °F). [10]
The discotic nematic phase includes nematic liquid crystals composed of flat-shaped discotic molecules without long-range order. In this phase, molecules do not form specific columnar assemblies but only float with their short axes in parallel to the director (a unit vector which defines the liquid-crystalline alignment and order).
An example of a calamitic mesogen type rigid core is a benzyl cyanide based rod molecule, where the smectic A liquid crystal phase exists between the 60 °C (crystal) and 62 °C (isotropic liquid phase) temperature range. [2]
In optics, a nematicon is a spatial soliton in nematic liquid crystals (NLC). The name was invented in 2003 by G. Assanto. [1] and used thereafter [2] [3] Nematicons are generated by a special type of optical nonlinearity present in NLC: the light induced reorientation of the molecular director (i.e. the average molecular orientation).
The first report of a thermotropic biaxial nematic appeared in 2004 [1] [2] based on a boomerang shaped oxadiazole bent-core mesogen. The biaxial nematic phase for this particular compound only occurs at temperatures around 200 °C and is preceded by as yet unidentified smectic phases. Biaxial nematic boomerang liquid crystal