Polystyrene Blend Alignment Layers for Pretilt Angle Control of Liquid Crystal

Abstract

We prepared blend alignment layer based on polystyrene containing 7-hydroxycoumarin (P7COU) and polystyrene containing 2-naphthoxy (P2NAP) side groups for liquid crystal (LC) alignment. The LC cells made from the rubbed P7COU/P2NAP blended films exhibited a shift of the LC alignment direction by approximately 20° compared with those made from a polystyrene film. Stable and homogeneous planar LC cells having pretilt angles adjustable from 0° to 5° were obtained from these polymer films having molar contents of P7COU and P2NAP in the ranges of 100–80 and 0–20 mole%, respectively. The LC alignment behavior was well correlated with the wettability of the polymer films.

Keywords:

• Alignment
• liquid crystal
• polystyrene
• pretilt angle

Acknowledgments

Financial support by the Samsung Electronics Co. Ltd. and Soongsil University is gratefully acknowledged. Authors express their gratitude to Prof. J.-C. Lee at Seoul National University for useful discussions.