Surface Alignment Effect and Pretilt Angle Generation in NLC with Oblique Non-Polarized UV Light Irradiation on Polymer Surface

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Abstract
In this study, we have investigated the generation of pretilt angle in nematic liquid crystal (NLC) in the cell with oblique non-polarized ultraviolet (UV) light irradiation on two kinds of the polyimide (PI) surfaces. It was found that the monodomain alignment in NLC is obtained having a PI surface without side chain. We successfully observed that the generated pretilt angle of the NLC is about 3° with an angle of incidence of 70° on the PI surface without side chain. It is considered that the pretilt angle generation in NLC is attributed to the interaction between the LC molecules and the polymer surfaces due to photo-depolymerization reaction. Also, the uniform alignment of NLC is attributed to anisotropic dispersion force due to photo-depolymerization of polymer on PI surfaces.