ALIGNMENT AND ALIGNMENT DYNAMICS OF NEMATIC LIQUID-CRYSTALS ON LANGMUIR-BLODGETT MONO-LAYERS

Mono-layers of stearic and behenic acids, deposited with the Langmuir- Blodgett technique, were used as aligning films in nematic liquid crys tal cells. During the filling process the liquid crystal adopts a defo rmed quasi-planar alignment with splay-bend deformation and preferred orientation along the filling direction. This state is metastable and transforms with time into a homeotropic state once the flow has ceased . The transition is accompanied by formation of disclination lines whi ch nucleate at the edges of the cell. The lifetime of the metastable s play-bend state was found to depend on the cell thickness. On heating, an anchoring transition from quasi-homeotropic to degenerate tilted a lignment in the form of circular domains takes place near the transiti on to the isotropic phase. The anchoring transition is reversible with a small hysteresis.