|92. Schlaad, H.; Schmitt, B.; Müller, A.H.E.; Jüngling, S.; Weiss, H.: Mechanism of anionic polymerization of (meth)acrylates in the presence of aluminium alkyls, 5. Effect of Lewis bases on kinetics and molecular weight distributions, Macromolecules 31, 573 (1998)|
The addition of esters like methyl pivalate or diisooctyl phthalate prevents the formation of the coordinative network of living polymer chains which is usually formed during the anionic polymerization of methyl methacrylate in the presence of aluminum alkyls in toluene. At a sufficiently high ester concentration, first-order time-conversion plots and polymers with narrow molecular weight distributions are obtained. The polymerization has living character in the temperature range from -78 to 0 °C. Similar results are obtained with multidentate ethers, especially crown ethers. Strong monodentate Lewis bases like tetrahydrofuran or N-methylpyrrolidine do also prevent the network formation, but the monomer conversion is not quantitative and the molecular weight distributions are broadened.