Substitute Effect of Fluorine-containing Polyimides with Hexafluoroisopropylidene Group on Photo Alignment of Liquid Crystal Molecule

The substituent effect of fluorine-containing polyimides with 4,4-(hexafluoro-isopropylidene) diphthalic anhydride (6FDA) group on the photo alignment of the liquid crystal (LC) molecule and the effect of 254 nm linearly polarized ultraviolet (LPUV) irradiation on the chemical structure were systema...

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Bibliographic Details
Published in:Journal of Photopolymer Science and Technology 2011/12/26, Vol.24(6), pp.617-623
Main Authors: Sato, Shuichi, Ito, Hiroto, Mizunuma, Tatsuro, Nagai, Kazuyuki, Matsumoto, Hironaga, Matsumoto, Setsuko
Format: Article
Language:English
Subjects:
Alignment
Anhydrides
Chemical bonds
fluorine-containing polyimide
Imides
Irradiation
liquid crystal
Liquid crystals
molecular orbital calculation
optical property
photo alignment
Polyimide resins
Segments
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Summary:The substituent effect of fluorine-containing polyimides with 4,4-(hexafluoro-isopropylidene) diphthalic anhydride (6FDA) group on the photo alignment of the liquid crystal (LC) molecule and the effect of 254 nm linearly polarized ultraviolet (LPUV) irradiation on the chemical structure were systematically investigated. 6FDA-2,3,5,6-tetramethyl-1,4-phenylene diamine (TeMPD) showed the photo alignment characteristic of the LC molecule. Based on the infrared and ultraviolet absorption spectra, the photo-scission reaction of LPUV irradiation was not observed, though photoreaction between polymer segments was observed. The photo alignment characteristic of LPUV-irradiated 6FDA-TeMPD strongly depended on the photoreaction between the C=O group of the imide ring and the CH3 group for phenyl-group π-π* transitions. The chemical structure changed with the excitation of C=O double bonds and C-H bonds and the formation of hydroperoxide O-H between the intermolecular polymer segment through the LPUV irradiation mechanism. The electron-donating benzene ring and the electron-accepting imide ring then formed charge transfer complexes (CTCs) between the two sides of polymer chains; the combination with the alternation sequence to both cross sides was clearly formed. In one direction of the photoreaction in the CTC structure, 6FDA-TeMPD showed the photo alignment of the LC molecule.
ISSN:0914-9244
1349-6336
DOI:10.2494/photopolymer.24.617