Synthesis And Structure - Properties Of Phosphorylcholine - Containing Polyurethane

The synthesis and structure-properties study of the anti-coagulation biomaterials have attracted much attention of both academic and industrial researchers. Among the polymers possess blood compatibility, those with the zwitterionic lipid phosphatidylcholine at main-chain are foucsed in this thesis, because they show more similarity in micro-structures and self-assemble behavior with biological tissues than those with phosphorylcholine at the side chain. They show potential applications in the fields of biomedicine, including non-thrombogenic material, drug delivery nanoparticles, gene carrier, biosensors, artificial organs, etc.In our present work, polyurethane with zwitterionic phosphorylcholine on the main chain was synthesized and the structures were defined with FT-IR and1HNMR. The mechanical (tensile strength, elastic modulus) and biological (platelet adhesion) evaluations of its blend films with polyurethane were of satisfactory results, which were in accordance with the requirements of the medical devices, showing their potential applications as anti-coagulant biomaterials. The dielectric spectroscopy was recorded with solid films and with films in water. The dielectric dispersion of the solid films demonstrated the existence of condensed ionic structures, which lead to the rigidity enhancement of the soft segment of the phosphorylcholine-based polyurethane, so that its elastic modulus increased. The dielectric measurement with films in water, providing a measurement for the surface properties in the aqueous environment, offered a semi-quantitative description of the interface dynamics of the material with a double-layer model, based on which a new hypothesis on the mechanism of blood or bio-compatibility was proposed that the hydrated surface of the satisfactory biomaterials can response to the outside electromagnetic stimuli with slight strength and prompt relaxation.