Manipulation of Defect Structures and Colloidal Chains in Liquid Crystals by Means of Photochemical Reactions of Azobenzene Compounds

• Published in: Molecular Crystals and Liquid Crystals Vol. 498; no. 1; pp. 1 - 10
• Main Authors: Yamamoto, Takahiro, Tabe, Yuka, Yokoyama, Hiroshi
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis Group 25-02-2009; Taylor & Francis Ltd
• Subjects: azobenzene; Chemical compounds; Chemical engineering; Chemical reactions; hedgehog; Liquid crystal polymers; liquid-crystal colloid; Molecules; Saturn ring
• ISSN: 1542-1406; 1563-5287; 1527-1943; 1543-5318
• DOI: 10.1080/15421400802611971

Photonic control of defect structures and colloidal chains has been performed in azobenzene-containing liquid crystals dispersed with glycerol or water droplets. When we dispersed the colloidal droplets into the host liquid crystals, we could observe, at an initial state, Saturn ring and hedgehog around the glycerol and water droplets, respectively, indicating that normal alignment of liquid crystal molecules was induced on the droplets by the adsorption of the azobenzene molecules onto the droplets. In the case of the glycerol droplets, we achieved photochemical manipulation of the defect structures between Saturn ring and boojums on irradiation with ultra-violet and visible light. For the water droplets, an inter-droplet distance of the self-organized colloidal chain could be controlled by changes of the defect size on the photoirradiation. Photoinduced structural changes in the topological defects can be explained by the modulation of surface anchoring of the droplets by means of the
cis-trans
photoisomerization of the adsorbed azobenzene molecules.