Introduction to Liquid Crystals and Their Molecular Order

Abstract

Liquid crystals constitute a state of matter in which the degree of molecular order is intermediate between the crystalline solid and the isotropic liquid. A liquid crystalline phase or mesomorphic phase can be attained either by varying temperature (thermotropic) or by adding a solvent (lyotropic). There are a variety of liquid crystalline phases which can be classified on the basis of the molecular order. Although different techniques like miscibility and optical observation of textures have been used to identify the different types of liquid crystalline phases, the most comprehensive understanding of the nature of the molecular order can be arrived at only by X-ray diffraction studies on oriented samples. The experimental techniques for X-ray investigations on liquid crystals vary depending on the nature of information that one is seeking.KeywordsLiquid CrystalReciprocal SpaceNematic PhaseOrientational OrderPositional OrderThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.