Lactide/trimethylene carbonate triblock copolymers: Controlled sequential polymerization and properties

Abstract Controlled synthesis and characterization of a series of copolymers comprising repeating units derived from D,D-lactide (D,D-LA) and trimethylene carbonate (TMC) is reported. Diblock PTMC- b -PDLA or PDLA- b -PTMC and finally triblock PTMC- b -PDLA- b -PTMC or PDLA- b -PTMC- b -PDLA copolymers have been prepared for the first time in a controlled way via sequential polymerization of the corresponding comonomers. The initiating/catalytic system based on Al-alkoxide that bears a bulky, optically active diphenolate ligands has been chosen for this purpose, since it quantitatively depresses a segmental exchange side-reactions. In order to improve the thermal properties of thus obtained materials, triblock copolymers: PTMC- b -PDLA- b -PTMC and PTMC- b -PLLA- b -PTMC of the opposite configuration of PLA sequence, have been used for the preparation of the corresponding stereocomplex. Microstructure, morphology, and thermal properties of thus prepared copolymers have been investigated by 13 C NMR, SEM, DSC, and TGA measurements.