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Proceedings Paper

Photoresponsive smart surface of LC azo-dendrimer: photomanipulation of topological structures and real-time imaging at a nano-scale
Author(s): Fumito Araoka; Alexey Eremin; Satoshi Aya; Guksik Lee; Atsuki Ito; Hajnalka Nadasi; Nerea Sebastian; Ken Ishikawa; Osamu Haba; Ralf Stannarius; Koichiro Yonetake; Hideo Takezoe
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Paper Abstract

In this paper, we review some results on our recent studies on photo-induced phenomena of liquid crystals (LCs) by means of interfaces decorated with a photo-responsive azobenzene dendrimer (azo-dendrimer). The azo-dendrimer molecules doped in a LC are spontaneously segregated from bulk and adsorbed onto substrate/LC or solvent/LC interfaces, and their photo-isomerization can bring about the so-called anchoring transition, i.e. reversible switching between homeotropic and planar alignment states of the bulk LC, when exposed to UV/VIS light. In addition to photoinduced anchoring transition in a LC cell, several interesting photo-induced phenomena through the azo-dendrimerdecorated interfaces have been reported, such as photo-induced transformation of the interior topological structures of nematic, cholesteric and smectic droplets, photo-mechanical motion of the micro particles dispersed in a nematic matrix, and optical assistance of the athermal anchoring transition with the aid of a perfluoropolymer surface. In addition to such phenomena, we also discuss the conditions of such photo-responsive interfaces in terms of the polar anchoring energy at the interface upon photo-isomerization under illumination of UV and/or VIS lights. The anisotropy of the polar anchoring energy was evaluated experimentally by means of Polarization Microscopy (POM), Dielectric Spectroscopy (DS), Second Harmonic Generation (SHG), and Attenuated Total Reflection Fourier Transform Infrared (ATR-IR) Spectroscopy, and theoretically based on the simple Rapini-Papoular model. We also demonstrate the continuous bulk orientation change by the photo-dynamic process through the fine control of the polar anchoring energy. Besides, the state-of-the-art video-rate atomic force microscopy (ν-AFM) was carried out to visualize the dynamics of such interfaces at a nano-meter scale.

Paper Details

Date Published: 15 February 2017
PDF: 8 pages
Proc. SPIE 10125, Emerging Liquid Crystal Technologies XII, 101250H (15 February 2017); doi: 10.1117/12.2251128
Show Author Affiliations
Fumito Araoka, RIKEN (Japan)
Alexey Eremin, Otto-von-Guericke Univ. Magdeburg (Germany)
Satoshi Aya, RIKEN (Japan)
Guksik Lee, Tokyo Institute of Technology (Japan)
Atsuki Ito, Tokyo Institute of Technology (Japan)
Hajnalka Nadasi, Otto-von-Guericke Univ. Magdeburg (Germany)
Nerea Sebastian, Otto-von-Guericke Univ. Magdeburg (Germany)
Ken Ishikawa, Tokyo Institute of Technology (Japan)
Osamu Haba, Yamagata Univ. (Japan)
Ralf Stannarius, Otto-von-Guericke-Univ. Magdeburg (Germany)
Koichiro Yonetake, Yamagata Univ. (Japan)
Hideo Takezoe, Toyota Physical and Chemical Research Institute (Japan)

Published in SPIE Proceedings Vol. 10125:
Emerging Liquid Crystal Technologies XII
Liang-Chy Chien, Editor(s)

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