Alignment of nematic liquid crystals on photo-irradiated polyamide–imide surfaces

✍ Scribed by David C. Rich; Enid Sichel; Peggy Cebe

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 359 KB
• Volume: 65
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19970808)65:6<1151::aid-app11>3.0.co;2-x

✦ Synopsis

The UV-induced alignment of nematic liquid crystals on Probimide 32 preimidized polyamide-imide surfaces is investigated. Exposing the polymer layer to linearly polarized deep UV ( l Å 254 nm) produces an aligning effect comparable to that achieved by mechanically brushing the polymer film. A laser optical transmission method is used to evaluate the efficacy of the process. It is shown that strong alignment is produced within minutes of exposure and is maintained with very long exposures. Atomic force microscopy and dichroic Fourier transform infrared spectroscopy reveal that brushed polyamide-imide surfaces are highly grooved and oriented, while the UV-exposed polymer surfaces are not.