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Kinetics of photoinduced birefringence in the guest–host system of poly(methyl methacrylate) doped with azobenzene‐containing crown ethers
Author(s) -
Shimizu Flávio Makoto,
Volpati Diogo,
Giacometti José Alberto,
Sworakowski Juliusz,
Janus Krzysztof,
Luboch Elżbieta
Publication year - 2007
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.26105
Subject(s) - azobenzene , birefringence , kinetics , materials science , exponential decay , relaxation (psychology) , methyl methacrylate , isomerization , poly(methyl methacrylate) , polymer chemistry , methacrylate , time constant , reaction rate constant , photochemistry , chemistry , polymer , optics , composite material , polymerization , physics , organic chemistry , psychology , social psychology , catalysis , electrical engineering , quantum mechanics , nuclear physics , engineering
The kinetics of the buildup and decay of photoinduced birefringence was examined in a series of host–guest systems: azobenzene‐containing crown ethers, differing in the size of the crowns, dissolved in a poly (methyl methacrylate) matrix. In all samples, the kinetics of the buildup of the birefringence was reasonably described by a sum of two exponential functions, the time constants being inversely proportional to the intensity of the pumping light and the magnitudes of the signals at the saturation level depending on the pumping light intensity and sample thickness. The dark decays were best described by the stretched exponential function, with the characteristic parameters (time constant and stretch coefficient) being practically independent of the type of crown ether. The time constants of the signal decay were orders of magnitude shorter than the respective constants of the dark isomerization of the azo crown ethers, thus indicating that the process controlling the decay was a relaxation of the polymer matrix and/or a rearrangement of the flexible parts of the crowns. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 105: 130–136, 2007