Planar alignment of columnar discotic liquid crystals by isotropic phase dewetting on chemically patterned surfaces

Jonathan P. Bramble, Daniel J. Tate, Derek J. Revill, Khizar H. Sheikh, James R. Henderson, Feng Liu, Xiangbing Zeng, Goran Ungar, Richard J. Bushby, Stephen D. Evans

    Research output: Contribution to journalArticlepeer-review

    Abstract

    A novel method of creating planar aligned columnar discotic liquid crystals (cDLCs) on surfaces, which also gives control over the azimuthal angle, is presented. Surfaces are chemically patterned with stripes via microcontact printing of organothiol self-assembled monolayers (SAMs) on gold, or via deep UV patterning of organosilane SAMs on silicon. These are then used to isolate long droplets of cDLCs by dewetting in the isotropic phase. Upon cooling from the isotropic into the hexagonal columnar phase, polarizing microscopy reveals that the cDLC aligns in a planar orientation. Results for three triphenylene derivatives (HAT-6, HHTT, H7T) and for a phthalocyanine derivative (8H 2Pc) are presented. H7T and HAT-6 are found to align with the director perpendicular to the stripe direction, but HHTT and 8H2Pc align parallel to the stripe direction. This relatively simple new method for creating planar aligned columnar phases of DLCs gives control over the azimuthal angle: a condition required for organic field-effect transistor applications of cDLCs. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.
    Original languageEnglish
    Pages (from-to)914-920
    Number of pages6
    JournalAdvanced Functional Materials
    Volume20
    Issue number6
    DOIs
    Publication statusPublished - 24 Mar 2010

    Keywords

    • Liquid crystals
    • Self-assembled monolayers
    • Organic field-effect transistors

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