Abstract
EtAlCl2/SnCl4 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.
