ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
ESR spectra of radicals produced from the reactions of phenyl methacrylate (PMA) and four o-substituted PMAs, 2,4,6-trimethyl-, 2,6-diisopropyl-, 2,6-di-tert-butyl-, and 2,6-di-tert-butyl-4-methyl-PMAs, with tert-butyoxy radical were measured in 2-methyltetrahydrofuran over the temperature range of -53 to -15°C. The coupling constants of the β-methylene protons observed varied with the bulkiness of the o-substituents, whereas the p-substitution did not affect the pattern of the spectra. 2,6-Diisopropyl- and 2,4,6-timethyl-PMAs, which can form homopolymers, gave 5- and 13-line spectra, respectively. For the radicals from 2,6-di-tert-butyl- and 2,6-di-tert-butyl-4-methyl-PMAs, the same 8-line spectrum was observed, indicating that the coupling constant of one of the β-methylene protons was too small to detect. Conformations of the radicals were deduced from the coupling constants of the β-methylene protons. Variation of the ESR spectrum according to the bulkiness of the o-substituent was interpreted as a consequence of steric interactions between the polymer chain bound to the β carbon and the substituents, and the α-methyl group.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1983.170210809
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