Alignment defects, displays

XRD samples 638 f alignment defects, displays 756 alignment materials, displays 732 aliphatic chains 125,395 alkanes, solvents 883 alkanoic acids, esterification alkanols, esterification 106 alkenes, solvents 883 alkenyl, terminal substituents alkyl functionalization, arenes alkyl groups... 

The FLCs or AFLCs mentioned above are liquid crystalline materials showing a chiral smectic C phase or related phases. Although nematic liquid crystal possesses only directional order, smectic liquid crystals shows layer structures or periodic order of the liquid crystalline molecular centres. In this respect, smectic liquid crystalline materials have more in common with crystalline materials than with nematic liquid crystalline materials. As a result, the alignment of smectic liquid crystal is quite different from that of nematic liquid crystals. Smectic liquid crystals show a large variety of defects because they possesses highly ordered structiu-es. Moreover, the layer structures are irreversibly destroyed by applying stress. This phenomenon poses a major problem for display applications. Therefore, several techniques to prevent the application of force to the liquid crystalline materials of FLC or AFLC devices have been proposed. 

The molecular alignment of liquid crystals on solid surfaces is not only of fundamental interest in physics [1] but is also relevant for practical applications, for example in optoelectronic devices. In liquid crystal displays the molecules are confined between two surfaces. To minimize the number of defects, surfaces are favored that induce a high degree of orientation of the molecules. Different surface treatments are used to induce and control the orientation of the molecules. A homeotropic (perpendicular) alignment is favored on hydrophobic surfaces that are rough on a molecular level. This is observed in adsorbed monolayers of a surface-active compound such as lipids or surfactant molecules on glass, both for energetic and sterical reasons. Surface modifications can alter the positional order and molecular orientation of liquid crystalline... 

---