Stereospecific Polymerization of o-Methoxy-α-methylstyrene

Takano, Hidekazu; Yuki, Heimei

doi:10.1295/polymj.1.403

Cited by 6 publications

(2 citation statements)

References 12 publications

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“…Recently 19), and OICAMOTO et aZ. 18) presented evidence supporting the assignment first reported by BROWN-STEIN et al, but it seems not t o be conclusive as yet.…”

Section: Johnson Heatley and Boveymentioning

confidence: 85%

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Carbon‐13 nuclear magnetic resonance spectroscopy of polystyrene and poly‐α‐methylstyrene

1972

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The carbon-13 high resolution nuclear magnetic resonance spectra with proton spin decoupling of polystyrene and poly-a-methylstyrene were measured. The spectra clearly split corresponding to triad, tetrad, and partially pentad placements, and these peaks were tentatively assigned. By comparison of the triad tacticity of poly-a-methylstyrene deteLmined from carbon-I3 spectra with that from proton spectra, it was confirmed that the nuclear OVERHAUSER effect due to proton decoupling has little effect on the relative intensities of the peaks assigned to chemically equivalent carbons except for stereochemical configuration.The stereospecific polymerization mechanisms are discussed on the basis of the microtacticity determined from carbon-13 spectra. As a result, it is concluded that poly-a-methylstyrene polymerized with cationic and anionic catalysts can be described by BERNOULLIAN statistics, while the atactic polystyrene does not obey BERNOULLIAK but first or second order MARKOVIAN statistics. ZUSAMMENFASSUNG:Hochaufgeloste 13C-NMR-Spektren von Polystyrol und Poly-a-methylstyrol werden unter Bedingnng der 1H-Spinentkopplung aufgenommen. Die Spektren zeigen klare Aufspaltungen, die den Triaden, Tetraden und teilweise den Pentaden entsprechen ; die verschiedenen Signale werden versuchsweise zugeordnet. Durch Vergleich der Triaden-Taktizitaten von Poly-a-methylstyrol auf Grund der 13C-NMR-Spektren mit den Protonea-Spektren konnte gezeigt werden, daB der OVERHAUSER-Effekt die relativen Intensitaten der Signale von chemisch aquivalenten Kohlenstoffatomen nur wenig beeinfluBt, mit Ausnahme bei der stereocbemischen Konfiguration.Die Mechanismen der stereospezifischen Polymerisation werden auf der Grundlage der durch W-NMR bestimmten Mikrotaktizitat dlskutiert. Die kationische und die anionische Polymerisation von a-Methylstyrol kann durch die BERNOULLI-Statistik beschrieben werden, wogegen das ataktische Polystyrol der MARKOV-Statistik gehorcht.

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“…Recently 19), and OICAMOTO et aZ. 18) presented evidence supporting the assignment first reported by BROWN-STEIN et al, but it seems not t o be conclusive as yet.…”

Section: Johnson Heatley and Boveymentioning

confidence: 85%

“…All of the latest papers report. [16][17][18][19]) that the assignment due to BROWNSTEIN et ~1 . 1 3 ) is the most probable one.…”

Section: Poly -A-methylstyrenementioning

confidence: 92%