Novel synthesis of biodegradable linear and star block copolymers based on ε-caprolactone and lactides using potassium-based catalyst

Biodegradable, triblock poly(lactide)-block-poly(epsilon-caprolactone)-block-poly (lactide) (PLA-b-PCL-b-PLA) copolymers and 3-star-(PCL-b-PLA) block copolymers were synthesized by ring opening polymerization of lactides in. the presence of poly(epsilon-caprolactone) diol or 3-star-poly(epsilon-caprolactone) triol as macroinitiator and potassium hexamethyldisilazide as a catalyst. Polymerizations were carried out in toluene at room temperature to yield monomodal polymers of controlled molecular weight. The chemical structure of the copolymers was investigated by H-1 and C-13-NMR. The formation of block copolymers was confirmed by NMR and DSC investigations. The effects of copolymer composition and molecular structure on the physical properties were investigated by GPC and DSC. (C) 2008 Wiley Periodicals, Inc.