Structure and Dynamics of Micellar Aggregates in Aqueous Nafion Solutions Reported by Electron Spin Resonance and Fluorescence Probes
| Autor: | Marian Wolszczak, and Andrzej Plonka, Shulamith Schlick, Ewa Szajdzinska-Pietek |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
chemistry.chemical_classification
Polymers and Plastics Organic Chemistry Fluorescence spectrometry Analytical chemistry Fluorescence spectroscopy law.invention Inorganic Chemistry Spin probe chemistry.chemical_compound chemistry law Nafion Materials Chemistry Electron paramagnetic resonance Ionomer Hyperfine structure Alkyl |
| Zdroj: | Macromolecules. 32:7454-7460 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/ma990710t |
| Popis: | Aqueous solutions of Nafion, an ionomer consisting of a perfluorinated backbone and pendant sulfonic groups, were studied by the electron spin resonance (ESR) spin probe method and by fluorescence spectroscopy. The spin probes used were 4-(N,N-dimethyl-N-alkyl)ammonium-2,2,6,6-tetramethyl-piperidine-1-oxyl cations (CATn) with n, the number of carbon atoms in the alkyl group of the probe, equal to 1 (CAT1), 8 (CAT8), and 16 (CAT16). The ESR spectra of the probes were analyzed in terms of line shapes as a reflection of the local dynamics and 14N hyperfine splittings as indicators of the local polarity. The line shapes point to slower dynamics for the larger probes, CAT8 and CAT16, suggesting that these probes are located deeper inside the aggregates compared to CAT1. The high local polarity reflected in the magnetic parameters was explained by assuming water penetration into the aggregates. The local polarity was estimated from the intensity ratio, R, of the third to the first vibronic peaks (R = IIII/II) i... |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|