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Modulation of the Photophysical Properties of Pyrene by the Microstructures of Five Poly(alkyl methacrylate)s Over a Broad Temperature Range

Authors

  • Teresa D. Z. Atvars,

    1. Chemistry Institute, State University of Campinas (Unicamp), Campinas, Brazil
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  • Shibu Abraham,

    1. Department of Chemistry and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC
    Current affiliation:
    1. SBG Labs, Inc., Sunnyvale, CA.
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  • Anita J. Hill,

    1. CSIRO Materials Science and Engineering and Process Science and Engineering, South Clayton, Vic., Australia
    2. Monash University, Department of Materials Engineering and Chemistry, Clayton, Vic., Australia
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  • Steven J. Pas,

    1. CSIRO Materials Science and Engineering and Process Science and Engineering, South Clayton, Vic., Australia
    2. Monash University, Department of Materials Engineering and Chemistry, Clayton, Vic., Australia
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  • Carlos Chesta,

    1. Departamento de Química, Universidad Nacional de Río Cuarto, Río Cuarto, Argentina
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  • Richard G. Weiss

    Corresponding author
    1. Department of Chemistry and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC
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  • This article is part of the Special Issue dedicated to the memory of Elsa Abuin.

Abstract

Pyrene fluorescence spectra have been recorded in five poly(alkyl methacrylate)s (where alkyl is ethyl butyl, isobutyl, cyclohexyl and hexadecyl) over a 20–400 K temperature range. The changes in the position and the full width at half maximum (FWHM) of the 0–0 emission band (peak I) have been correlated with the structural characteristics of the alkyl groups in the different relaxation regimes of the polymers to assess the degree of coupling of the excited singlet states with the polymer cybotactic regions. Data treatment of the peak I positions using an electron–phonon model indicates that longitudinal optical modes are involved, and that the magnitude of coupling depends on the polymer structure and follows the same trend as the glass transition temperatures. The same spectral parameters have been correlated also with “hole” free volumes from positron annihilation spectroscopy over temperature ranges which span the glass or melting transitions of the polymers. Reasons why free volume and FWHM measurements follow the same trends, and other aspects of the systems, are discussed.

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