Abstract
We have investigated the alignment of polyimide backbone structures induced by single oblique angle irradiation with un-polarized light (UP-light) of wavelength 340 ∼ 500 nm. The polyimide (Azo-PI) used in this study contains azobenzene in the backbone structure. The alignment of the backbone structure occurs through random angular rotation of the azobenzene molecule accompanied by its photoinduced trans-cis-trans isomerization. The photo-alignment treatment was performed on 16 nm thick films of polyamic acid (Azo-PAA) that is the precursor of Azo-PI. Subsequently, the Azo-PAA film was thermally imidized. The UP-light exposure was varied up to 882 J/cm2. The orientational distribution of the Azo-PI backbone structure was determined, using polarized infrared absorption spectroscopy. We found that the average inclination angle and the in-plane order parameter of the backbone structure increased with UP-light exposure, reaching 51° from the surface plane and 0.1, respectively, at 882 J/cm2.
Original language | English |
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Pages (from-to) | 215/[1779]-226/[1790] |
Journal | Molecular crystals and liquid crystals |
Volume | 438 |
DOIs | |
Publication status | Published - 2005 |
Keywords
- Azobenzene
- Liquid crystal
- Photo-induced alignment
- Photo-isomerization
- Polarized IR absorption
- Polyimide
ASJC Scopus subject areas
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics