Synthesis and characterization of a new biodegradable polyurethanes with good mechanical properties

In the paper, a new biodegradable polyurethane(PU, PU-I) was prepared:the prepolymer was synthesized via bulk ring-opening polymerization with poly(ethylene glycol)(M_n=600)(PEG600) as an initiator and _L-lactide(_L-LA), e-caprolactone(CL) as monomers, and the prepolymer was chain-extended with an isocyanate-terminated urethane triblock(macrodiisocyanate) to prepare the PU. The macrodiisocyanate, prepolymer and PUs were characterized by ¹H NMR, ¹³C NMR, FT-IR, high resolution mass spectrometry(HR-MS), gel permeation chromatography(GPC), thermo gravimetric analysis(TGA), and differential scanning calorimetry(DSC). The corresponding PU films showed excellent mechanical properties with a tensile strength of 27.5 MPa and an elongation at break of 996%, and also maintained mechanical properties in physiological saline at 37℃ for more than three weeks, which appeared to be more suitable for biomedical applications.