Abstract

Background: The present work is part of a general study regarding the homo- and copolymerization of styrene using diphenylzinc-additive initiator systems, with the aim of improving the properties of commercial atactic polystyrene. The study is focused on syndiotactic polystyrene and/or copolymers of styrene (S) with substituted styrene, styrene derivatives or various ?-olefins. This research has been ongoing over the last 15 years. Results: The reported experiments show that binary metallocene-methylaluminoxane (MAO) and ternary Ph 2Zn-metallocene-MAO, depending on the metallocene employed, are capable of inducing both homo- and copolymerization of styrene and p-methoxystyrene (p-MeOS). The results indicate that for a styrene/ p-MeOS mole ratio with p-MeOS > 25% the product obtained has only a minor incorporation of styrene units. The efficiency of the metallocenes studied follows the order bis(n-butylcyclopentadienyl)titanium dichloride ((n-BUCP) 2TiCl 2) > indenyltitanium trichloride (lndTiCl 3) > CP 2TiCl 2. Conclusion: Metallocenes (n-BuCP) 2TiCl2, CP 2TiCl2 and IndTiCl 3 in binary systems combined with MAO, as well as in ternary systems combined with Ph 2Zn and MAO, induce the homopolymerization of p-MeOS and its copolymerization with styrene. The styrene/p-MeOS copolymer obtained was enriched in p-MeOS with respect to the initial feed, in agreement with the I+ inductive effect of the methoxy group in the para position of styrene. As already reported, the role of Ph 2Zn was nullified by its complexation with the p-MeOS comonomer. © 2008 Society of Chemical Industry.