Synthesis and characterization of novel polyimides containing stilbene unit in the side chain and their controllability of nematic liquid crystal alignment on the rubbed surfaces

Authors

  • J. H. Park,

    Corresponding author
    1. Center for Advanced Functional Polymers and Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Korea
    Current affiliation:
    1. Neutron Physics Department, HANARO Center, Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, Taejon 305-600, Korea
    • Center for Advanced Functional Polymers and Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Korea
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  • J. C. Jung,

    1. Center for Advanced Functional Polymers and Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Korea
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  • B.-H. Sohn,

    1. Center for Advanced Functional Polymers and Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Korea
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  • S. W. Lee,

    1. Department of Chemistry, Center for Integrated Molecular Systems, and Polymer Research Institute, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Korea
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  • M. Ree

    1. Department of Chemistry, Center for Integrated Molecular Systems, and Polymer Research Institute, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Korea
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Abstract

Four polyimides containing hexylene spacer and a fluorostilbene unit in the side chains were prepared in thin-film form by two-step condensation of 3,3′-bis[(4′-fluoro-4-stilbenyl)oxyhexyloxy]-4,4′-biphenyldiamine (FS6B) with pyromellitic dianhydride (PMDA), benzophenone-3,3′,4,4′-tetracarboxylic dianydride (BTDA), 4,4′-oxydi(phthalic anhydride) (ODPA), and 4,4′-hexafluoroisopropylidenedi(phthalic anhydride) (6FDA), respectively, and their controllability of liquid crystal (LC) alignment on rubbed surfaces was investigated. Pretilt angles of LCs were achieved in the 2–9° range, depending on the rubbing density and backbone structures. The effect of the mesogenic stilbene group on the pretilting of LCs was distinctive in FS6B-PMDA. Contact-angle measurements on thin films annealed at 120 °C revealed that FS6B-PMDA potentially had the better alignment stability than FS6B-6FDA. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3622–3632, 2001

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