Synthesis of biodegradable polycaprolactone/polyurethane by curing with H2O

To prepare a pre-polymer in this study, the following materials were used: 4,4'-diphenylmethane diisocyanate, poly(e-caprolactone) diol (PCL), and polytetramethylene ether glycol. The pre-polymer was then cured using H2O to form a new type of polyurethane (PU), PCL/H2O-PU. Fourier transform infrared analysis confirmed the successful synthesis of PCL/H2O-PU. Results from thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis showed that the thermal resistance and glass transition temperature of PCL/H2O-PU increased with the H2O and the hard segment content. Stress-strain curves for the PCL/H2O-PU specimens showed that with increasing H2O content, the tensile strength and Young's modulus increased, but the elongation at break decreased. WAXD patterns indicated that with a higher H2O content, the polymer chains were in a more ordered arrangement, although the morphology was still amorphous. The degree of swelling in an aqueous ethanol solution and the hydrolytic degradation rate increased with the PCL content. Scanning electron microscopic images showed that during the degradation period, the original wrinkled surface of PCL/H2O-PU became smooth, and then cracks were formed. The cracks became more severe when the degradation was at a higher temperature.