Polymerization of methyl methacrylate with achiral 4B group metallocene compounds

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Abstract
Methyl methacrylate (MMA) was polymerized with Cp2ZrCl2/ methylalyminoxane or Cp2M(CH3)2 (M: Zr, Hf; Cp = cyclopentadienyl) combined with B(C6F5)3 (1) or Ph3CB(C6F5)4 (2), (Ph = phenyl). in the presence of a Lewis acid like Zn(C2H5)2 with slow inititation, which gave syndiotactic‐rich poly(methyl methacrylate) (PMMA) with high molecular weight. The polymer yield increases with polymerization time, which indicates that the propagation rate is zero order in concentration of monomer. The polymer yield increases also with concentration of Cp2Zr(CH3)2.2, which indicates the zirconocene to be the real catalyst. The polymer yield and the initiation efficiency (N/[Zr]) increase with the concentration of Zn(C2H5)2, which indicates Zn(C2H5)2, to be involved in the initiation. It is also shown that the propagation reaction is independent of the concentration of Zn(C2H5)2.