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Homogeneous Alignment
In liquid crystals homogeneous alignment, sometimes called planar alignment, is the state of alignment where molecules align in parallel to a substrate. The opposite method is homeotropic alignment In liquid crystals 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 may flow like a liquid, but its molecules may be oriented in a .... For planar alignment - polyimides can be used. One of the popular ones is PI-2555. The surface has to be rubbed by paper or by a velvet or similar cloth in order to make the alignment axis parallel to the rubbing. However the exact mechanism of this alignment is not entirely clear. Liquid crystals {{chem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liquid Crystals
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 may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many types of LC phases, which can be distinguished by their optical properties (such as textures). The contrasting textures arise due to molecules within one area of material ("domain") being oriented in the same direction but different areas having different orientations. LC materials may not always be in a LC state of matter (just as water may be ice or water vapor). Liquid crystals can be divided into 3 main types: *thermotropic, *lyotropic, and * metallotropic. Thermotropic and lyotropic liquid crystals consist mostly of organic molecules, although a few minerals are also known. Thermotropic LCs exhibit a phase transition into the LC phase as temperature changes. Lyotropic LCs exhibit phase transitions as a function of both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homeotropic Alignment
In liquid crystals, homeotropic alignment is one of the ways of alignment of liquid crystalline molecules. Homeotropic alignment is the state in which a rod-like liquid crystalline molecule aligns perpendicularly to the substrate. In the polydomain state, the parts also are called homeotropic domains. In contrast, the state in which the molecule aligns to a substance in parallel is called homogeneous alignment. There are various other ways of alignment in liquid crystals. Because homeotropic alignment is not anisotropic optically, a dark field is observed between crossed polarizers in polarizing optical microscopy. By conoscope observation, however, a cross image is observed in the homeotropic alignments. Homeotropic alignment often appears in the smectic A phase 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 may flow like a liquid, but its molecules may be orien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
