Liquid Crystal
Definition and meaning of Liquid Crystal in chemistry.
A liquid crystal is a unique state of matter that exhibits properties intermediate between those of a conventional isotropic liquid and those of a highly ordered solid crystal.
In more detail
While the molecules in a liquid crystal can flow like a liquid, they maintain a significant degree of orientational or positional order similar to a solid crystal lattice. Liquid crystals are extremely sensitive to external stimuli such as changes in temperature, electric fields, and magnetic fields, which can rapidly alter their molecular alignment and, consequently, their optical properties. They are broadly classified into thermotropic liquid crystals, which are temperature-dependent, and lyotropic liquid crystals, which are concentration-dependent. Common mesophases include the nematic, smectic, and cholesteric phases.
Key facts
| Field | Physical Chemistry |
|---|---|
| Mesophases | Nematic, smectic, cholesteric |
| Triggers | Temperature or concentration |
The display of a digital calculator relies on twisted nematic liquid crystals, where an applied electric field changes the orientational alignment of the molecules, turning specific segments dark to display numbers by blocking polarized light.
Frequently asked questions
What is the nematic phase in a liquid crystal?
In the nematic phase, molecules lack positional order but exhibit long-range orientational order, meaning they tend to point in the same general direction.
Are cell membranes liquid crystals?
Yes, biological cell membranes are a classic example of lyotropic liquid crystals consisting of lipid bilayers.