EtAlCl
2/SnCl
4 is an initiating system for the living cationic polymerization of various
p-substituted styrenes in the presence of added bases, but neither
cis- nor
trans-β-methylstyrene (βMeSt) can be polymerized by it. In contrast, after adding
p-methylstyrene, the random copolymerization of
trans-βMeSt proceeded, producing copolymers with up to 30% of βMeSt content as confirmed by
1H and
13C NMR spectroscopy. In addition, long-lived cationic species were observed at −78°C, which could not be observed in the polymerization of the
cis-isomer. The copolymer of the
trans-isomer had a higher stereoregularity compared to that of the
cis-isomer. Copolymerization of
trans-anethole, a more reactive βMeSt derivative having a
p-methoxy group, with pMeSt proceeded in an alternating fashion. Thus, the successful copolymerization of βMeSts, generally considered difficult to polymerize, was achieved by the judicious choice of the comonomer with appropriate reactivity and a suitable initiating system.
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