We investigated new rubbing-free techniques for liquid crystal (LC) alignment with non-polarized ultraviolet (UV) light irradiation on plates coated with two kinds of the polyimide (PI) films. It was found that monodomain alignment of nematic (N) LC is obtained in the cell having a PI surface without a 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 chains. This pretilt angle generation is attributed to interaction between the LC molecules and the polymer surfaces; the uniform alignment of NLC is attributed to anisotropic dispersion force effects due to photo-depolymerization of polymer on PI surfaces.
Bibliographical noteFunding Information:
The authors wish to acknowledge H. Fukuro of Nissan Chemical Industries Co., Ltd for providing PI materials. This research was supported by a Grant of Development of Advanced Tehncologies for Flat Panel Displays of the Ministry of Science and Tehncology and Ministry of Trade, Industry and Energy of Korea.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics