Solid-state deuterium nuclear magnetic resonance of the methyl dynamics of poly(α-methylstyrene) and polymethylphenylsilane
| Autor: | E. J. Ginsburg, Frank D. Blum, Robert D. O'Connor |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | The Journal of Chemical Physics. 112:7247-7259 |
| ISSN: | 1089-7690 0021-9606 |
| DOI: | 10.1063/1.481288 |
| Popis: | The methyl-d3 dynamics of two relatively similar polymers, poly(α-methylstyrene) (PAMS-d3) and polymethylphenylsilane (PMPS-d3), are investigated via deuterium NMR relaxation experiments. Our analysis of the relaxation data uses the entire solid-echo spectra to maximize the precision of the experiments with regard to the information available on the methyl dynamics. The analysis is novel in that it does not use M∞ or M0 to fit the relaxation data. Additionally, the three-site symmetric jump model is shown to not have an observable azimuthal angular dependence for T1 relaxation. The methyl dynamics are quantified with τm, σ, and f which are the log-average correlation time, half-height full-width (base 10) of a log-normal distribution of reorientation rates, and the anisotropy of the relaxation, respectively. The anisotropy parameter, f, is based on a serial combination of the rotational diffusion and symmetric three-site jump reorientation of a methyl deuteron. This serial model coupled with a distributio... |
| Databáze: | OpenAIRE |
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