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Type: Artigo de periódico
Title: Synthesis, photophysical properties and thermal relaxation processes of carbazolyl-labeled polysiloxanes
Author: Domingues, RA
Yoshida, IVP
Atvars, TDZ
Abstract: The photophysical properties of a fluorescent silicone prepared by a hydrosilylation reaction from poly(dimethylsiloxane-co-methylhydrogensiloxane) terminated by dimethylhydrogensilyloxy groups, poly(dimethylsiloxane-co-methylvinylsiloxane) terminated by dimethylvinylsilyloxy groups and 9-vinylcarbazole, as the luminescent group, have been studied under steady-state fluorescence and time-resolved conditions. At low temperature both steady-state fluorescence and phosphorescence spectra of isolated species are observed. Phosphorescence is quenched at temperatures higher than 150K indicating that the environments where the carbazolyl moieties are located are very flexible, as expected for silicones. Fluorescence decays and phosphorescence (at 77K) showed typical carbazolyl lifetimes and no rise-time was observed, which is consistent with the absence of excimer emission. The temperature dependence of the emission can be used to determine the polymer relaxation processes and transitions (T-gamma = 80-100 K, T-g = 130-150K and T-m = 220 K), these last two comparable with those observed by differential scanning calorimetry. (C) 2010 Elsevier B.V. All rights reserved.
Subject: Silicone
Photophysical property
Thermal relaxation
Country: Suíça
Editor: Elsevier Science Sa
Citation: Journal Of Photochemistry And Photobiology A-chemistry. Elsevier Science Sa, v. 217, n. 41700, n. 347, n. 355, 2011.
Rights: fechado
Identifier DOI: 10.1016/j.jphotochem.2010.11.003
Date Issue: 2011
Appears in Collections:Unicamp - Artigos e Outros Documentos

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