Photochemical transformation of topological defects formed around colloidal droplets dispersed in azobenzene-containing liquid crystals

Takahiro Yamamoto, Yuka Tabe, Hiroshi Yokoyama

    Research output: Contribution to journalArticle

    12 Citations (Scopus)

    Abstract

    We investigated photochemical transformation of asymmetric topological defects formed around water droplets dispersed in the azobenzene-containing liquid crystals. It was found that initial structures and the photo-induced phenomena of the defects were clearly affected by chemical structures of the azobenzene compounds. In quite strong homeotropic anchoring obtained by using the azobenzene compound with a long alky chain, the hedgehog was formed around the droplets at the initial state. When the anchoring strength was decreased by changing the carbon number of the alkyl chain, a novel asymmetric defect which will be an intermediate structure between the hedgehog and the Saturn ring was observed. The ionic groups had an influence on the photochemical transformation of the defects. The azobenzene compound with a smaller ionic group induced only a change in the anchoring strength, and a disappearance of the hedgehog was observed on the irradiation with ultra-violet light. In the case of the azobenzene compound with a larger ionic group, photochemical switching of the anchoring and the transformation into the boojums was achieved. The photo-induced phenomena could be qualitative explained by an effectiveness of the cis-trans photoisomerization depending on molecular areas of the azobenzene compounds determined by the ionic groups.

    Original languageEnglish
    Pages (from-to)155-159
    Number of pages5
    JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
    Volume334
    Issue number1-3
    DOIs
    Publication statusPublished - 2009 Feb 20

    Fingerprint

    Liquid Crystals
    Azobenzene
    Liquid crystals
    liquid crystals
    Defects
    defects
    Saturn rings
    ultraviolet radiation
    Photoisomerization
    irradiation
    azobenzene
    carbon
    Carbon
    Irradiation
    water
    Water

    Keywords

    • Azobenzene
    • Liquid-crystal emulsion
    • Surface anchoring

    ASJC Scopus subject areas

    • Colloid and Surface Chemistry

    Cite this

    Photochemical transformation of topological defects formed around colloidal droplets dispersed in azobenzene-containing liquid crystals. / Yamamoto, Takahiro; Tabe, Yuka; Yokoyama, Hiroshi.

    In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 334, No. 1-3, 20.02.2009, p. 155-159.

    Research output: Contribution to journalArticle

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