Anchoring Competition on Nanosurface Boundaries with Conflicting Mixed Nematic Anchoring Properties

We propose a technique for continuously controlling the full range of pretilt angles with a high process margin. The proposed method is characterized by tuning the thickness of a heterogeneous polyimide layer that consists of homeotropic and planar polyimides. The thickness of the mixture can be controlled by varying the concentration of the solvent. The liquid crystal (LC) pretilt generated at the very thin mixture film is insensitive to some incorrect mixing ratio, since the segregation of the depth direction of the mixture including the van der Waals effect in interactions with LCs decreases ultimately. Consequently, we can obtain continuous LC pretilt angles with a high process margin by controlling mixing ratio in a very thin heterogeneous polyimide film. Furthermore, it is possible to achieve excellent reliability, uniformity, and productivity using this technique. A simple mathematical model based on van der Waals interaction provides a good description of the experimental results. (C) 2012 The Japan Society of Applied Physics