RT Journal Article
T1 Solvent and Temperature Effects on Polymer-Coated Glass Fibers. Fluorescence of the Dansyl Moiety
A1 González Benito, Francisco Javier
A1 Aznar Jiménez, Antonio
A1 Baselga Llidó, Juan
AB E-type glass fibers were coated with poly(γ-aminopropyltriethoxysilane), treating them with a 1% (v/v) monomer aqueous solution. The fibers were labeled with a dansyl-sulfonamide conjugate by reaction of acetonitrile solutions of dansyl chloride with the amine groups immobilized on the glass fiber surface. Interactions of the labeled coating polymer with solvents of different polarities were estimated by measurements of the fluorescence band shifts of the label. It was found that for aprotic solvents, the solvent dipolar coupling relaxation mechanism is dominated by thermodynamic interactions of the solvent with the polymer matrix, while for protic solvents this mechanism is dominated by specific interactions between solvent molecules and the excited state of the chromophore. Different experimental excited-state dipole moments were obtained for nonpolar and polar solvents (μ*ₙₚ = 7.2 ± 1.6 D, μ*ₚ = 11.9 ± 1.5 D). Using the AM1 method, excited-state dipole moments for the first and second singlets were calculated and it was concluded that μ*ₚ ≃ 〈μ*²₁〉½ and μ*ₚ ≃ 〈μ*²₂〉½. Accordingly, neither the glass support nor the coating polar influence the excited-state properties of dansyl. The temperature dependence of dansyl emission allows the determination of the relaxation temperature of the coating polymer, which was estimated as 175 K for the coating used.
PB Plenum Publishing Corporation
SN 1053-0509
YR 2001
FD 2001-12
LK https://hdl.handle.net/10016/25832
UL https://hdl.handle.net/10016/25832
LA eng
NO The authors wish to thank the UE Brite EuRam program (BE97-4472) and CAM (07N/0002/1998) for financial support.
DS e-Archivo
RD 1 sept. 2024