The effects of surface morphological mechanics on liquid crystal alignment characteristics using photo-activators
- Authors
- Lee, In Hye; Shin, Dong Myung
- Issue Date
- 24-May-2019
- Publisher
- TAYLOR & FRANCIS LTD
- Keywords
- Liquid Crystal Alignment; Photo-Activator; Photo-Fragment Reaction; Radical Generation; Surface Morphology Analysis
- Citation
- MOLECULAR CRYSTALS AND LIQUID CRYSTALS, v.685, no.1, pp.47 - 54
- Journal Title
- MOLECULAR CRYSTALS AND LIQUID CRYSTALS
- Volume
- 685
- Number
- 1
- Start Page
- 47
- End Page
- 54
- URI
- https://scholarworks.bwise.kr/hongik/handle/2020.sw.hongik/1559
- DOI
- 10.1080/15421406.2019.1645460
- ISSN
- 1542-1406
- Abstract
- Photo-activators, which produce carbon dioxide, are highly reactive radical generators upon UV light illumination. In this study, the generated radicals selectively reacted with the polyimide (PI) main chains and created a liquid crystal alignment layer with a high level of azimuthal anchoring energy. The thickness of the photo-irradiated PI alignment layer was reduced dramatically by photo-induced radical crosslinking, which induced surface wrinkling and roughness. Moreover, the carbon dioxide and methane gases that were generated during photo-irradiation produced many micro-pores, which also attributed to holding the LC molecules tightly on the PI surfaces. The level of azimuthal anchoring energy that was obtained by photo-alignment was better than what was obtained by the rubbing method with the same PI, specifically, the maximum value of the photo-alignment with the photo-activator was 6.92 x 10(?5) J/m(2) than 1.11 x 10(?5) J/m(2) of the rubbing. We proposed a mechanism based on a high anchoring energy, a rough surface, a hydrophilic surface, and rapid photo-reactions.
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Collections - College of Engineering > Chemical Engineering Major > 1. Journal Articles
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