Photochemical manipulation of colloidal structures in liquid-crystal colloids

T. Yamamoto, Y. 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 publicationLiquid Crystals and Applications in Optics
DOIs
Publication statusPublished - 2007 Nov 26
EventLiquid Crystals and Applications in Optics - Prague, Czech Republic
Duration: 2007 Apr 172007 Apr 18

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6587
ISSN (Print)0277-786X

Conference

ConferenceLiquid Crystals and Applications in Optics
CountryCzech Republic
CityPrague
Period07/4/1707/4/18

Keywords

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

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

Fingerprint Dive into the research topics of 'Photochemical manipulation of colloidal structures in liquid-crystal colloids'. Together they form a unique fingerprint.

  • Cite this

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