Synthesis and characterization of poly(ϵ-caprolactone)-poly(L-lactide) diblock copolymers with an organic amino calcium catalyst

The quasiliving characteristics of the ring‐opening polymerization of ϵ‐caprolactone (CL) catalyzed by an organic amino calcium were demonstrated. Taking advantage of this feature, we synthesized a series of poly(ϵ‐caprolactone) (PCL)–poly(L‐lactide) (PLA) diblock copolymers with the sequential addition of the monomers CL and L‐lactide. The block structure was confirmed by 1H‐NMR, 13C‐NMR, and gel permeation chromatography analysis. The crystalline structure of the copolymers was investigated by differential scanning calorimetry and wide‐angle X‐ray diffraction analysis. When the molecular weight of the PLA block was high enough, phase separation took place in the block copolymer to form PCL and PLA domains, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2654–2660, 2006