Thermotropic liquid crystals advantages

An equally important observation for the above copolyester LCPs is that the ordered arrangement of polymeric mesophases in the melt is retained upon cooling, which is manifested in greatly improved mechanical properties (see Figure 5.5b). The liquid crystalline behavior is therefore advantageous from the standpoint of both processing and properties. Thermotropic liquid crystal copolyesters of structures similar to (I) are now available commercially. 

It was realized in the early 1970s that the unusual properties of thermotropic liquid crystals held great promise for use in flat-panel electronic displays and other optical control applications. The advantages particular to Uquid crystals of a very large (if not especially fast) electrooptic effect induced by CMOS-compatible voltages and of microwatts per square centimeter power consumption were identified at an early stage. With the discovery of chemically stable nematic liquid crystals, such as the... 

Another advantage of this in situ synthesis is that the LC anisotropic medium may induce a morphology-controlled growth of NPs, i.e. control over size and shape. Whereas this last approach has been often reported in the case of lyotropic liquid crystals, (Saliba et al. 2013 Hegman et al. 2007) the use of thermotropic liquid crystals is seldomly found in literature. For this specific purpose, the use of LC polymers has demonstrated its better efficiency than the use of small LC molecules. That will be discussed in the following paragraphs. 

The industrial development of thermotropic liquid crystal polymer (LCP) materials can be traced from its theoretical origins, through the identification of useful compositions, to full commercialization. The future industrial challenge will be to define and develop applications which take advantage of the unique properties of these materials. 

Liquid crystals, as the name implies, are condensed phases in which molecules are neither isotropically oriented with respect to one another nor packed with as high a degree of order as crystals they can be made to flow like liquids but retain some of the intermolecular and intramolecular order of crystals (i.e., they are mesomorphic). Two basic types of liquid crystals are known lyotropic, which are usually formed by surfactants in the presence of a second component, frequently water, and thermotropic, which are formed by organic molecules. The thermotropic liquid-crystalline phases are emphasized here they exist within well-defined ranges of temperature, pressure, and composition. Outside these bounds, the phase may be isotropic (at higher temperatures), crystalline (at lower temperatures), or another type of liquid crystal. Liquid-crystalline phases may be thermodynamically stable (enantiotropic) or unstable (monotropic). Because of their thermodynamic instability, the period during which monotropic phases retain their mesomorphic properties cannot be predicted accurately. For this reason it is advantageous to perform photochemical reactions in enantiotropic liquid crystals. 

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