Synthesis, characterization and degradation of poly(2,2-dimethyl trimethylene carbonate- co-ϵ-caprolactone- co-glycolide)

Abstract

Degradable tri-component copolymers were synthesized by the bulk copolymerisation of 2,2-dimethyl trimethylene carbonate (DTC), ϵ-caprolactone (CL) and glycolide (GA) using stannous octanoate as catalyst at 140 °C for 36 h. The mole fraction ratio in the feed of DTC and CL was fixed at 20/80 and the mole percent of GA was varied to obtain copolymers with different properties. The polymerisation products were characterized by 1H NMR, 13C NMR, FT-IR, GPC and DSC. It was found that the hydrophilicity of these materials increased with increasing GA content, according to measurements of static contact angles of distilled water on the surface of polymer films. Mechanical tests and hydrolytic degradation assays showed that copolymers of different degradability and mechanical properties could be tailored by adjusting the compositions. For the polymer P-3 (GA content about 10 mol%), the tensile strength and the elastic modulus could reach 4.3 MPa and 22 MPa, respectively. It took 4 weeks for the copolymer P-3 to degrade to about 82% ( M n, t / M n,0) and 10 weeks to 40%. These low crystallinity copolymers could be processed into porous films with stable structures by means of combination of solvent volatilisation with salt leaching. These materials are expected to be useful for nerve reconstruction and other biomedical applications.