Abstract
Polymerization of methyl methacrylate (MMA) by the three component catalytic system Cp2ZrMe2/B(C6 F5)3/ZnEt2 (1), in toluene, under thoroughly purified conditions, was found to produce polymers of high molecular weights (MW > 60 × 103), low polydispersities (MW/Mn = 1.12-1.22) and almost quantitative yields. The polymerization process is characterized by a pronounced induction period followed by a rapid and constant rate of polymerization. The molecular weight of PMMA increases by increasing the conversion and is proportional to the ratio of [MMA]0/[Zr]0, while MW/Mn remains intact, meaning that the present polymerization proceeds in a well-controlled fashion. Evidence for effects of [ZnEt2] and temperature 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 weight distribution, in very high conversion. Well-controlled copolymerization of MMA with n-hexyl methacrylate was 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 catalytic system. Evidence for the aggregation of the polymeric products in THF and toluene solutions was found by static and dynamic light scattering. The comparison of the polymerization results of this work with other studies clearly shows that in order to obtain improved molecular characteristics, thorough purification protocols should be applied.
Original language | English (US) |
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Pages (from-to) | 4697-4705 |
Number of pages | 9 |
Journal | Macromolecules |
Volume | 34 |
Issue number | 14 |
DOIs | |
State | Published - Jul 3 2001 |
Externally published | Yes |
ASJC Scopus subject areas
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry