| Polyurethane materials, which are widely used in biomedical fields for artificial blood vessel or catheters and other medical instrument, have played an important role in biomedical materials. However, when polyurethane materials touch living organisms, some undesirable or adverse biological reactions (for example, forming thrombus and causing inflammation) would occur. Therefore, it is important to improve the biocompatibility, especially the blood compatibility, of polyurethane biomaterials. Many methods are used to improve the blood compatibility of polyurethane (PU) films, including blending, surface coating, covalence bonding and grafting.In this thesis, we modified polyurethane materials by blending and grafting, respectively. Their structure, thermostability and hydrophilicity were characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetic analysis (TGA) and surface water contact angle measurement, respectively. Mechanical properties such as tensile strength, Young’s Modulus, strain at break, were also evaluated, and the results suggested that mechanical properties of the modified polyurethane materials were evidently improved, compared with those of pure polyurethane materials. The effects of grafting temperature, grafting time, monomer and initiator concentrations on the grafting rates and water absorbency were also studied. The results showed that the three vinyl hydrophilic monomers were successfully grafted onto the surface of PU films, respectively, and the hydrophilicity of the grafted PU films were improved significantly. Meanwhile, their blood compatibility was investigated by protein adsorption, platelet adhesion, haemolysis, and MTT assay. The results showed that the amount of the adsorbed protein and that of the adhered platelet on the modified PU films is obviously lower than that on pure PU films, respectively, and the hemolysis ratio is also up to international standards. |
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