Kinetic and thermodynamic considerations in the synthesis of a new three‐arm poly(ε‐caprolactone)

A new high‐molecular‐weight three‐arm poly(ε‐caprolactone) (PCL) polymer was synthesized in bulk (in the absence of any solvent) by using aluminum tri‐sec butoxide as a tri‐functional initiator. The ring‐opening polymerization of ε‐caprolactone occurs via a coordination‐insertion mechanism that links three growing polyester chains to the Al central atom via metal alkoxide bonds. The global kinetics of the bulk polymerization was determined, and a kinetic model based on monomer‐polymer equilibrium was developed to predict the fractional extent of monomer conversion. Monomer conversions in excess of 95% to form high‐molecular‐weight PCL were achieved. Polym. Eng. Sci. 44:1491–1497, 2004.