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Proceedings Paper

Generation of high pretilt in photo-aligned polyimides
Author(s): John L. West; Michinori Nishikawa; Yuri A. Reznikov
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Paper Abstract

Liquid crystals have been shown to align on polarized UV (PUV) exposed polyimide films with the liquid crystal director oriented perpendicular to the polarization direction. Uniform pretilt is produced by a second oblique PUV exposure. We report here the factors controlling liquid crystal alignment and pretilt on photo-exposed polyimide films. We show that the chemistry of the polyimide controls the liquid crystal aligns either parallel or perpendicular to the PUV. Also, the tilt angle of the liquid crystal can be varied continuously between 0 degrees and 90 degrees by adjusting the polyimide chemistry. Our results indicate that the liquid crystal has uniform pretilt with no preferred alignment direction on unexposed polyimide. Normal exposure aligns the director but the pretilt is degenerate, pointing in either the plus or minus direction. Oblique exposure breaks this degeneracy, producing a unique pretilt direction. We show that uniform alignment and pretilt can be produced with a single oblique exposure if the liquid crystal aligns parallel to the polarization direction.

Paper Details

Date Published: 26 March 1999
PDF: 8 pages
Proc. SPIE 3635, Liquid Crystal Materials, Devices, and Applications VII, (26 March 1999); doi: 10.1117/12.343868
Show Author Affiliations
John L. West, Kent State Univ. (United States)
Michinori Nishikawa, Japan Synthetic Rubber Co. (Japan)
Yuri A. Reznikov, Institute of Physics (Italy)

Published in SPIE Proceedings Vol. 3635:
Liquid Crystal Materials, Devices, and Applications VII
Ranganathan Shashidhar, Editor(s)

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