著者

宇佐美 清章 坂本 謙二 荒谷 毅 潮田 資勝

出版者

一般社団法人 日本液晶学会

雑誌

日本液晶学会討論会講演予稿集 (ISSN:18803490)

巻号頁・発行日

vol.1999, pp.6-7, 1999

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We have measured the polarized infrared (IR) absorption spectra of poly[4,4'-oxydiphenylen-l,2,3,4- cyclobutanetetracarboxyimide] (CBDA-ODA) films irradiated with linearly polarized ultraviolet light (LPUVL) of wavelength 〜 250 nm. The measurement was carried out for a very thin film (10 nm thick) as a function of the LPUVL exposure. The dichroic difference, A_⊥- A_//, of the phenyl C-C stretching vibration of CBDA-ODA, which is polarized along the polyimide chain, has a maximum around 3 J/cm^2. Here A_//and A_⊥ are the absorbance for the IR light polarized parallel and perpendicular to the polarization direction of LPUVL, respectively. The dichroic difference per unit film thickness at 3 J/cm^2 was greater than that of a rubbed CBDA-ODA film with the same film thickness. Although the average IR absorbance, (A_⊥+ A_//)/2, decreases monotonically over the entire measurement range of LPUVL exposure, A_⊥ increases up to 1 J/cm^2. This result shows that the number of polyimide molecules oriented perpendicular to the polarization direction of LPUVL increases. We conclude that the photo-induced orientation contributes to the large surface anisotropy of LPUVL-exposed CBDA-ODA films in addition to the anisotropic photo-induced decomposition.