| Abstract
| - Polymerization of methyl methacrylate (MMA) by the three component catalytic systemCp2ZrMe2/B(C6F5)3/ZnEt2 (1), in toluene, under thoroughly purified conditions, was found to producepolymers of high molecular weights (Mw> 60 × 103), low polydispersities (Mw/Mn = 1.12−1.22) and almostquantitative yields. The polymerization process is characterized by a pronounced induction period followedby a rapid and constant rate of polymerization. The molecular weight of PMMA increases by increasingthe conversion and is proportional to the ratio of [MMA]0/[Zr]0, while Mw/Mn remains intact, meaningthat the present polymerization proceeds in a well-controlled fashion. Evidence for effects of [ZnEt2] andtemperature in the molecular characteristics of the final products are also presented in this study.Moreover, the catalytic system 1 was found to catalyze the polymerization of other alkyl methacrylates(alkyl = n-butyl, n-hexyl) to high molecular weight syndiotactic materials, with narrow molecular weightdistribution, in very high conversion. Well-controlled copolymerization of MMA with n-hexyl methacrylatewas successful by the effective catalytic action of 1, leading to multiblock polymeric structures.Copolymerization of MMA with stearyl methacrylate was also achieved, with the above-mentioned catalyticsystem. Evidence for the aggregation of the polymeric products in THF and toluene solutions was foundby static and dynamic light scattering. The comparison of the polymerization results of this work withother studies clearly shows that in order to obtain improved molecular characteristics, thoroughpurification protocols should be applied.
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