What are the types of liquid crystals?
There are three types of liquid crystal: nematic, smectic and cholesteric. In the liquid crystalline phase, the vector about which the molecules are preferentially oriented, n, is known as the “director”.
What are liquid crystals made of?
They change shape like a fluid but have the molecular alignment characteristics of a solid crystal. Liquid crystals are composed of organic, rod-shaped molecules that align in parallel, and the common types used in electronic displays are nematic, cholesteric and smectic.
What is meant by lyotropic liquid crystals?
A liquid crystalline mesophase is called lyotropic (a portmanteau of lyo- “dissolve” and -tropic “change” ) if formed by dissolving an amphiphilic mesogen in a suitable solvent, under appropriate conditions of concentration, temperature and pressure.
What is LCP material?
Liquid crystal polymer (LCP) exhibits a highly ordered structure in both the melt and solid states. LCP can replace such materials as ceramics, metals, composites and other plastics because of its outstanding strength at extreme temperatures and resistance to virtually all chemicals, weathering, radiation and burning.
How liquid crystal is formed?
Liquid crystals that are formed by temperature change (“partial melting” of the solid phase) are called thermotropic liquid crystals. Lyotropic liquid crystals are formed due to changes in the concentration of surfactants in a solvent.
What are thermotropic and lyotropic liquid crystals?
Thermotropic liquid-crystals exhibit a phase transition into the liquid-crystalline state as temperature is raised [7]. Lyotropic liquid-crystals exhibit phase transitions as a function of both temperature and concentration of the liquid-crystal molecules in a solvent, which is typically water for biological molecules.
Why are liquid crystals important?
The most important use of liquid crystals is in displays because the molecules of a liquid crystal can control the amount, color, and direction of vibration of the light that passes through them. This means that by controlling the arrangement of the molecules, an image in light can be produced and manipulated.
What are the properties of LCP?
8.7. 2 LCPs Properties
| Property | Unit | LCP 1 |
|---|---|---|
| HDT at 1.8 MPa or 264 psi | °C | 105–187 |
| Melting point | °C | 212–280 |
| Tensile strength | MPa | 140–182 |
| Tensile elongation at break | % | 1.7–3.4 |
Is LCP A plastic?
Properties. Liquid crystalline polymers (LCPs) are a special type of thermoplastics that exhibit properties between highly ordered solid crystalline materials and amorphous disordered liquids over a well defined temperature range.
What are the structure of liquid crystals?
Liquid crystals are typically long, rigid molecules that can interact strongly with one another; they do not have isotropic structures, which are completely disordered, but rather have anisotropic structures, which exhibit different properties when viewed from different directions.
What is liquid crystal and its classification?
Liquid crystals are classified in many ways, molecules within the mesophases (mesogens) can be calamitic (rod-like), discotic (disc-like), amphiphilic, nonamphiphilic, metal containing, non-metal containing and low molecular weight or polymeric. Liquid crystals either show thermotropic behaviour or lyotropic behaviour.
What is the difference between nematic smectic and cholesteric liquid crystals?
The key difference between nematic smectic and cholesteric liquid crystals is their structure. Nematic liquid crystals have no ordered structure of molecules, and smectic liquid crystals have a layered molecular structure, whereas cholesteric liquid crystals have the molecules in a twisted and chiral arrangement.
What is LCP plastic used for?
Because of their various properties, LCPs are useful for electrical and mechanical parts, food containers, and any other applications requiring chemical inertness and high strength.
What are ferroelectric crystals?
Ferroelectric crystals exhibit a combination of extraordinary optical and electronic properties which make them widely used in optoelectronic devices.
Are ferroelectric liquid crystals suitable for display and spatial light modulators?
Ferroelectric liquid crystals remain of interest for display and spatial light modulators because they exhibit significantly faster optical response times than nematics. However, smectic layers are sensitive to shock-induced flow and are usually permanently displaced once a well-aligned sample is disrupted, rendering such devices inoperable.
What is F LCoS (ferroelectric liquid crystal)?
Using ferroelectric liquid crystal (FLC) in F LCoS technology allows a much smaller display area which eliminates the problems of manufacturing larger area FLC displays. Additionally, the dot pitch or pixel pitch of such displays can be as low as 6 μm giving a very high resolution display in a small area.
What is ferroelectricity and how does it work?
Ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field. All ferroelectrics are pyroelectric, with the additional property that their natural electrical polarization is reversible.