Surface-produced alignment of liquid crystals

The surface-generated orienting forces acting on liquid crystals (LC´s) result from physicochemical processes, e.g., hydrogen bonding, Van der Waal´s interactions, or dipolar interactions, and from mechanical interactions as a result of the LC´s anisotropic elasticity. For flat, untextured surfaces, the physicochemical processes prevail, while for textured surfaces, the anisotropic elastic interactions must also be considered. These sometimes competing processes are compared quantitatively, and the various orienting techniques and materials are discussed. It is shown that although both physicochemical and anisotropic elastic interactions are important, the former will typically predominate.