Polymerization of mixtures of alkyl methacrylates or alkyl acrylates with 4-methyl-1-pentene by Ziegler-Natta catalyst

Mixtures of methyl methacrylate (MMA) and 4-methyl-1-pentene (4MP)(molar ratio MMA/4MP = 3–0.1) have been subjected to polymerization by VOCl₃/Al(C₂H₅)₃. The amorphous polymeric products, extractable with boiling methanol up to 75%, consist mainly of MMA monomeric units (～80%). The composition of the product was almost independent of the starting MMA/4MP ratio. Comparison of these results with thoseof homopolymerization experiments shows that the presence of MMA drastically reduces the polymerization rate of 4MP. Moreover, 4MP is polymerized with rather low stereospecificity in the presence of MMA. Fractionation by solvent extraction of the unchanged polymeric products as well as of hydrolyzed samples seems to exclude the formation of random copolymers, suggesting to us that the polymerization of the two monomers takes place by different mechanisms. On taking into account these data and analogous data obtained with 4MP and alkyl acrylates or tert-butyl methacrylate, is it suggested that, contrary to what has previously been proposed, the MMA polymerization by Ziegler-Natta catalysts does not take place at the same centers which polymerize 4MP; moreover a coordinated anionic mechanism for MMA polymerization does not seem to be very probable.