Photochemical manipulation of colloidal structures in liquid-crystal colloids

T. Yamamoto, Yuka Tabe, H. Yokoyama

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    We investigated photochemical manipulation of physical properties and colloidal structures of liquid-crystal (LC) colloids containing azobenzene compounds. In a LC suspension where polymeric particles were dispersed in a host LC, we achieved photochemical control of light-scattering properties of the suspension. In a nematic phase, when the suspension was sandwiched with two glass plates, the film became opaque. This would be attributable to an appearance of both multidomain structures of LC alignment and mismatches of refractive indices between the materials. The opaque state turned into a transparent one when a nematic-to-isotropic phase transition was induced by the trans-to-cis photoisomerization of the azo-dye. This will result from a disappearance of both the multidomain structures and the refractive-index mismatches in the isotropic phase. The transparent film went back into the initial opaque film when the nematic phase was obtained by the cis-to-trans photoisomerization. In a LC emulsion in which glycerol or water droplets were dispersed in liquid crystals, we examined photochemical change of defect structures and inter-droplet distances by the photochemical manner. At the initial state, Saturn ring and hedgehog defects were formed around the droplets. For the glycerol droplets, we observed structural transformations between Saturn ring and boojums on irradiation with ultra-violet and visible light. For the water droplets, the inter-droplet distances varied by changing defect size on the irradiation. These phenomena would result from modulation of anchoring conditions of the droplets by the photoisomerization of the azo-dyes.

    Original languageEnglish
    Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
    Volume6587
    DOIs
    Publication statusPublished - 2007
    EventLiquid Crystals and Applications in Optics - Prague
    Duration: 2007 Apr 172007 Apr 18

    Other

    OtherLiquid Crystals and Applications in Optics
    CityPrague
    Period07/4/1707/4/18

    Fingerprint

    Colloids
    Liquid crystals
    colloids
    manipulators
    liquid crystals
    Photoisomerization
    Saturn rings
    glycerols
    Azo dyes
    Glycerol
    defects
    dyes
    Refractive index
    refractivity
    Irradiation
    irradiation
    Defects
    Azobenzene
    Defect structures
    water

    Keywords

    • Azobenzene
    • Boojums
    • Colloids
    • Hedgehog
    • Light-scattering
    • Liquid crystals
    • Photoisomerization
    • Saturn ring
    • Surface anchoring

    ASJC Scopus subject areas

    • Electrical and Electronic Engineering
    • Condensed Matter Physics

    Cite this

    Yamamoto, T., Tabe, Y., & Yokoyama, H. (2007). Photochemical manipulation of colloidal structures in liquid-crystal colloids. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 6587). [658707] https://doi.org/10.1117/12.722656

    Photochemical manipulation of colloidal structures in liquid-crystal colloids. / Yamamoto, T.; Tabe, Yuka; Yokoyama, H.

    Proceedings of SPIE - The International Society for Optical Engineering. Vol. 6587 2007. 658707.

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Yamamoto, T, Tabe, Y & Yokoyama, H 2007, Photochemical manipulation of colloidal structures in liquid-crystal colloids. in Proceedings of SPIE - The International Society for Optical Engineering. vol. 6587, 658707, Liquid Crystals and Applications in Optics, Prague, 07/4/17. https://doi.org/10.1117/12.722656
    Yamamoto T, Tabe Y, Yokoyama H. Photochemical manipulation of colloidal structures in liquid-crystal colloids. In Proceedings of SPIE - The International Society for Optical Engineering. Vol. 6587. 2007. 658707 https://doi.org/10.1117/12.722656
    Yamamoto, T. ; Tabe, Yuka ; Yokoyama, H. / Photochemical manipulation of colloidal structures in liquid-crystal colloids. Proceedings of SPIE - The International Society for Optical Engineering. Vol. 6587 2007.
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