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Updated: Sep 30, 2025
Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Vertical Alignment of Liquid Crystals on Phenylphenoxymethyl-Substituted Polystyrene-PS Derivatives Structurally
Jihyeon Moon1, Chaewon Kang1, Hyo Kang1
1BK-21 Four Graduate Program, Department of Chemical Engineering, Dong-A University, 37 Nakdong-Daero, 550 Beon-gil, Saha-gu, Busan 49315, Korea.
Abstract:
A series of polystyrene derivatives containing precursors of liquid crystal (LC) molecules, phenylphenoxymethyl-substituted polystyrene (PPHE#; # = 5, 15, 25, 50, 75, and 100)-where # is the molar content of 4-phenylphenol using polymer modification reactions-were prepared in order to examine the effect of the polymer film, which possess similar LC molecular structure on the LC alignment properties. It was found that the Tg values of the PPHE# were higher than 100 °C due to their aromatic structure in the biphenyl-based PHE moiety. The LC cells fabricated with PPHE5 and PPHE15 films exhibited planar LC alignment. Conversely, LC molecules showed a vertical alignment in LC cells made using the polymer films with phenylphenoxymethyl side groups in the range of 25-100 mol %. The polar surface energies on the PPHE# films can be associated with the vertical LC alignment on the PPHE# films. For example, vertical LC alignment was exhibited when the polar surface energy of the polymer films was less than approximately 4.2 mJ/m2. Aligning stability was observed at 200 °C and UV irradiation of 20 J/cm2 for LC cells made using the PPHE100 film. Therefore, it was found that biphenyl, one of the LC precursors, modified polystyrene derivatives and can produce a next-generation vertical LC alignment system.
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