• catalysts;
  • cooperative effects;
  • copolymerization


Heterometal alkoxide clusters of lanthanide and sodium, LnNa8[OC(CH3)3]10(OH) [where Ln = Nd (1) or Yb (2)], which were synthesized by the metathesis reaction of LnCl3 with NaOC(CH3)3 and NaOH in a 1 : 10 : 1 molar ratio in high yields and fully characterized including X-ray analysis for 2, were found to be highly active catalysts in the ring-opening polymerization of ε-caprolactone and trimethylene carbonate and their copolymerization. All of the polymers obtained showed a unimodal molecular weight distribution, indicating that 1 and 2 could really be used as single-component catalysts. The dependence of catalytic activity on the lanthanide metals was observed: Yb < Nd. A coordination–insertion mechanism for the ring-opening polymerization is proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009