Star‐shaped poly[(trimethylene carbonate)‐co‐(ε‐capro‐lactone)] and its block copolymers with lactide/glycolide: synthesis,characterization and properties

Linear and star‐shaped copolymers of trimethylene carbonate/ε‐caprolactone were synthesized using different polyol initiators and catalysts. Unexpectedly, when dipentaerythritol was used as an initiator cross‐linked rubbers were obtained, that swell in chloroform. This network formation can be understood by ‘in situ’ generation of cross‐linker molecules from trimethylene carbonate and initiator. SEC analysis showed that with D‐sorbitol star‐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‐(ε‐caprolactone)] rubber core based on D ‐sorbitol show good mechanical properties. At relatively low rubber content ductile tensile behavior was observed indicating extensive toughening.