Investigations of the mechanism of liquid-crystal alignment onrubbed polyimide films

• 作 者: 吴海明 朱扬明 杨晓敏 陆祖宏 韦钰 罗棋 孙政明
• 机 构: National Laboratory of Molecular and Biomolecular Electronics, Southeast University, Nanjing 210096,
• 出 处: Chinese Science Bulletin
• 发表日期: 1996年07期
• 关键词: alignment chains retardation fabrication belief coated macroscopic harmonic assu

Liquid crystals (LCs) can be easily oriented by surfaces on a macroscopic scale. Thisphenomenon, known as alignment or anchoring, plays a dominant role in the fabrication ofLC devices. Studying the alignment technique of LCs is of great importance from bothpractical and theoretical points of view. Recently, rubbed polyimide-coated glass substrates have been widely used in LC align-ment. A general belief about the mechanism by which such a polymer alignment methodworks is that alignment acts through the interaction between LC molecules and orientedpolymer chains. This assumption was demonstrated by Barmentlo et al. through surfacesecond-harmonic-generation and optical phase retardation measurements. However, theseoptical techniques can only provide the macroscopic and average information because they