Abstract
Proton and fluorine NMR spectra of chlorotrifluoroethylene–isobutylene copolymers with various compositions were measured. The fluorine resonances are explained in terms of tetrads, and the methyl resonances on the other hand, are interpreted in terms of triads. Not only the geminal fluorine atoms but also the geminal methyl groups were found to become nonequivalent to each other under the influence of one or two asymmetric centers in the copolymer chain. It was also found that the fluorine spectra show a marked temperature dependence in the range of 70 to 120°C. This suggests that the copolymers have rather high potential barriers for internal rotation, probably, because of their bulky substituents. A statistical treatment was made for the polymerization process, and the results suggest that there exists a penultimate effect in this copolymerization reaction.
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Ishigure, K., Tabata, Y. & Oshima, K. Nuclear Magnetic Resonance Spectra of Isobutylene– Chlorotrifluoroethylene Copolymer. II. Interpretation of Fluorine Resonances in Terms of Tetrads and Their Temperature Dependence. Polym J 2, 321–327 (1971). https://doi.org/10.1295/polymj.2.321
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DOI: https://doi.org/10.1295/polymj.2.321