Polystyrene local dynamics in dilute solution: Temperature and solvent dependence of C-D vector correlation function shape
✍ Scribed by Wei Zhu; M. D. Ediger
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 194 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
Variable temperature 2 H-NMR T 1 experiments were performed on backbone deuterated atactic polystyrene in four solvents at two Larmor frequencies. Temperature-frequency superposition, which is consistent with experimental results for many other polymers, cannot describe our data. This indicates that the shape of the correlation function for C-D vector reorientation is temperature dependent. A modified log x 2 distribution of relaxation times, i.e., a delta function plus a log x 2 distribution, was used to fit the experimental data. These fits are consistent with literature 13 C T 1 and NOE data. As polystyrene local dynamics slow down by a factor of 5, the FWHM of the log x 2 distribution increases from 0.8 to 1.1 decades. Solvent identity does not play a major role in determining the shape of the correlation function. The fraction of the correlation function decay caused by librational motion was determined to be 0.28. The quantity was compared for series of polymers and found to correlate with the size of the side group.