Synthesis and characterization of elastic PLGA/PCL/PLGA tri-block copolymers.

Various ABA-type tri-block copolymers composed of poly(L-lactide) (PLA) or poly (lactide-co-glycolide) (PLGA) as the side A block and poly(epsilon-caprolactone) (PCL) as the middle B block were synthesized to produce rapidly degrading elastic matrices useful for tissue engineering scaffolds. The terminal di-hydroxyl groups in PCL-diol (MW 2000) were used as the initiator for the ring-opening polymerization of L-lactide or D,L-lactide and glycolide, employing stannous octoate as a catalyst. A series of copolymers were synthesized by varying the chain length and monomer composition of the PLA (PLGA) block, while the chain length of the PCL block was fixed. It was found that PLGA/PCL/PLGA copolymers with a MW of 10000 and lactide/glycolide ratios of 50/50 and 75/25 demonstrated desirable mechanical properties of elasticity (Young's modulus 26.0 and 19.8 MPa) and showed controllable degradability over a 2-month period depending on the monomer composition.