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  • 1
    ISSN: 1573-4994
    Keywords: Solvent accessibility ; pyrenesulfonyl chloride ; glass fibers ; APES ; exciplex emission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract E-glass fibers were silanized using a 1% (v/v) aqueous solution of γ-aminopropyltriethoxysilane (APES). Pyrene—sulfonamide conjugates were formed by reaction of 1-pyrenesulfonyl chloride (PSC) in acetonitrile (AcN), with the amine groups immobilized on the glass fiber surface. These pyrene—sulfonamide conjugates were used as fluorescence probes, being a relatively simple analytical method to study the coating microstructure of polyorganosiloxane layer on glass fibers. The first aim of this work was to estimate possible interactions of the polyaminosiloxane coating with surrounding molecules of different solvents (solvent accessibility to the chromophore). For this study, the fluorescence response of pyrene—sulfonamide dye (PSA) was correlated with solvent polarity parameters. It was concluded that all the studied solvents were accessible to the chromophore, and they can gather in two groups, depending on their ability to swell the poliorganosiloxane layer. The second objective was to estimate the rigidity of the coating polymer from the temperature dependence of PSA emission. At about 180 K, a sudden change in the behavior of different photophysical parameters of PSA were observed. This phenomenon was interpreted as a density change in the polyaminosiloxane attached to the glass fibers.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-4994
    Keywords: Pyrenesulfonyl chloride ; glass fibers ; APES ; exciplex emission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Commercial glass fibers have been subjected to different activation treatments under neutral and acidic conditions to achieve different coating degrees when silanized with γ-aminopropyltriethoxisi lane (APES). A fluorescent sulfonamide (PSA) was formed between the amine residue and a fluorescent probe, pyrenesulfonyl chloride (PSC). Reflectance UV–Vis spectra of the pyrene-doped fibres show that pyrene is present in the form of preassociated dimers when the coating degree is low. Emission and excitation fluorescence spectra reveal the existence of a charge transfer ground-state complex with exciplex emission at 460–515 nm and absorption red-shifted with respect to the S0 → S1 transition. Lifetime measurements yield three lifetimes, which are assigned to dimer, exciplex, and monomer emission. From the photophysical data it is concluded that the fibers with the highest silane content have an open structure with the highest fraction of isolated fluorescent moieties.
    Type of Medium: Electronic Resource
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