Novel biodegradable copolyesters containing blocks of poly(3-hydroxyoctanoate) and poly (ε-caprolactone):: Synthesis and characterization

Novel biodegradable polyester block copolymers have been synthesized by using well-defined poly(3-hydroxyoctanoate)(PHO)oligomers having a hydroxyl end group and an ester end group with (M) over bar (n) values of 800, 2500, 5300, 8000, or 20000 as an elastomeric soft segment and poly-(epsilon-caprolactone) as a more crystalline segment. These PHO oligomers prepared by methanolysis were subjected to block copolymerization with epsilon-caprolactone. The chemical structure of the copolymers was confirmed by H-1 NMR and C-13 NMR spectroscopy. All the copolyesters are semi-crystalline and two T-g were observed by differential scanning calorimetry when the molecular weight of the PHO block is about 20000.