Star-shaped poly[(trimethylene carbonate)-co-(epsilon-caprolactone)] and its block copolymers with lactide/glycolide: synthesis, characterization andproperties

Linear and star-shaped copolymers of trimethylene carbonat/epsilon-caprolac tone were synthesized using different polyol initiators and catalysts. Unex pectedly, when dipentaerythritol was used as an initiator cross-linked rubb ers were obtained, that swell in chlorofonn. This network formation can be understood by 'in situ' generation of cross-linker molecules from trimethyl ene carbonate and initiator tor. SEC analysis showed that with D-sorbitol s tar-shaped copolymers are synthesized with an average functionality between 4 and 6. These low molecular weight rubbers were used as a macro-initiator for the subsequent lactide/ glycolide polymerization. Star-shaped lactide/ glycolide block copolymers with a poly[(trimethylene carbonate)co-(epsilon- caprolactone)] rubber core based on D-sorbitol show good mechanical propert ies. At relatively low rubber content ductile tensile behavior was observed indicating extensive toughening.