A versatile photochemical procedure to introduce a photoreactive molecular layer onto a polyimide film for liquid crystal alignment

作者：Sasaki Akira; Aoshima Hozumi; Nagano Shusaku^*; Seki Takahiro

来源：Polymer Journal, 2012, 44(6): 639-645.

DOI：10.1038/pj.2012.45

• azobenzene
• cinnamate
• liquid crystal cell
• photoalignment
• polyimide film
• surface modification
• vacuum ultraviolet light

A polyimide film containing a cholesteryl moiety spin-coated on a solid substrate is treated with vacuum ultraviolet light from a Xe-2(*) excimer lamp at 20 Pa. This procedure generates oxidized chemically functional groups, such as hydroxyl groups, selectively on the top-most surface without changing the nature of the bulk polymer. Onto the chemically functionalized surface, photofunctional units such as azobenzene and cinnamate units are attached at a monolayer or sub-monolayer level. When nematic liquid crystal (LC) cells are fabricated, such photoresponsive surfaces work as effective %26apos;command surfaces%26apos; for photoswitching the zenithal LC orientation and photoaligment layers to achieve the homogeneous azimuthal orientation applicable for vertical alignment mode LC devices. The proposed photochemical treatment provides a simple but versatile alternative process for the preparation of surface molecular films comparable to self-assembled monolayers or Langmuir-Blodgett films. Polymer Journal (2012) 44, 639-645; doi:10.1038/pj.2012.45; published online 28 March 2012

• 出版日期2012-6