11 October 2012 Photochemical manipulation of microparticles on azobenzene-doped liquid-crystal films with homogeneous or homeotropic alignment structures
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Abstract
In this study, we investigated self-organized structures and photoinduced motions of microparticles on azobenzenedoped liquid crystal (LC) films with homogeneous or homeotropic alignment structures. In the case of homogeneous alignment, the microparticles formed linear chains oriented along the direction of the bulk LC alignment at air–LC interface in the initial state. Upon irradiation with ultra-violet (UV) light, the linear chains gathered into the irradiated area and formed closely-packed aggregates. The assembled chains diffused outside the irradiated area to reform the chains upon irradiation with visible light. In contrast, on the homeotropically aligned LC films, pseudo-hexagonal lattice structures of microparticles with long interparticle distances have been organized in the initial state. The particles exhibited photoinduced motions in directions opposite to those observed on the homogeneously aligned LC films. Upon irradiation with UV light, lattice structures were expanded by a particle motion away from the photoirradiated area. Irradiation with visible light then induced contraction of lattice structures based on a particle motion toward the irradiated area. The photoinduced particle motions depending on LC alignments would be explained by macroscopic convective flow or deformation of LC surface induced by cis–trans photoisomerization of azobenzene dopant.
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Takahiro Yamamoto, Takahiro Yamamoto, Masaru Yoshida, Masaru Yoshida, } "Photochemical manipulation of microparticles on azobenzene-doped liquid-crystal films with homogeneous or homeotropic alignment structures", Proc. SPIE 8475, Liquid Crystals XVI, 847505 (11 October 2012); doi: 10.1117/12.928824; https://doi.org/10.1117/12.928824
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