Optical and dielectric characteristics of photochromic hybrid sol-gel materials |
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Authors: | M Serwadczak M Wübbenhorst S Kucharski |
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Institution: | (1) Faculty of Chemistry, Department of Polymer Engineering and Technology, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wrocław, Poland;(2) Department Natuurkunde en Sterrenkunde, Acoustics and Thermal Physics Section, Catholic University Leuven, B-3001 Heverle, Belgium;(3) Formerly: Delft University of Technology, The Netherlands |
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Abstract: | Photochromic silica based organic-inorganic hybrid materials containing covalently linked cyanoazobenzene chromophores were
investigated by optical and dielectric spectroscopy. These materials, obtained via sol-gel process, were deposited onto glass
substrates by spin coating technique to achieve thin transparent films. To investigate photoinduced alignment, the UV-Vis
absorption spectra of the sol-gel films were recorded under illumination with linearly polarized blue light. Dielectric relaxation
spectroscopy revealed a variety of relaxation processes: the α-process related to the dynamic glass transition temperature
located around 150°C, and an Arrhenius-type β-relaxation (activation energy 58–60 kJ/mol) that was assigned to orientational
fluctuations involving the azobenzene group. The correspondence between dielectric and photochemical behavior was discussed. |
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Keywords: | Sol-gel films Hybrid materials Diazo dye Dielectric relaxation spectroscopy Photochromic materials |
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