Inclined alignment of polyimide backbone structures induced by single exposure of un-polarized light

Kenji Sakamoto, Kiyoaki Usami, Toru Sasaki, Yoichi Uehara, Sukekatsu Ushioda

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

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 languageEnglish
Pages (from-to)215/[1779]-226/[1790]
JournalMolecular crystals and liquid crystals
Volume438
DOIs
Publication statusPublished - 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

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