The Tribological Properties Of Poly(2-methacryloxyethyl Phosphatidylcholine)grafted Ultra High Molecular Weight Polyethylene

2-methacryloyloxyethyl phosphatidylcholine polymer(PMPC)has good biocompatibility,hydrophilic and lubricating,the function of its side chain phospholipid polar group is similar to that of the natural articular cartilage and has good lubricity.Therefore,PMPC is a polymer that is applied to the surface modification of artificial joints improve wear resistance and lifespan of artificial joints.Copper is one kind of transition metal element,which can promote the denaturation of protein molecules between the tribo-pair and decomposing into a carbon-rich layer.The carbon-rich layer can reduce the friction coefficient of the tribo-pair and improve the wear resistance of the artificial joint.In this study,based on the good lubricity and biocompatibility of PMPC,Cu has the function of promoting the formation of carbon-rich lubricating layer.First,PMPC and methacrylic acid(MAA)are grafted ultra-high molecular weight polyethylene(UHMWPE)by photoinduced graft polymerization,and then immersed in a copper acetate solution to form a Cu-MAA/MPC composite coating,finally,the effect of copper ions on the wear resistance of PMPC coating during friction was studied.The microstructure and tribological properties of Cu-MAA/MPC composite coatings were investigated by Fourier transform infrared spectroscopy attenuated total reflection(FT-IR-ATR),X-ray photoelectron spectroscopy(XPS),water contact angle test,scanning electron microscope and wear test.The results show that:(1)The PMPC coating,Cu-MAA coating and Cu-MAA/MPC composite coating were successfully prepared by UV-induced graft polymerization,which could effectively reduce the friction coefficient of UHMWPE.(2)Study the different treatment time of benzophenone(BP),and find that the water contact angle of the sample treated for 30 minutes by the photosensitizer was lower than that of the sample treated for 20 minutes.The friction coefficient of the photosensitizer benzophenone for the sample treatment time of 30 min was lower than that of the sample with the treatment time of 20 min.(3)Study on PMPC coatings prepared at different concentration of 2-methacryloxyethyl phosphorylcholine(MPC),the results show that the friction coefficient of PMPC coating decreases with the increase of MPC concentration at different MPC concentrations.The friction coefficient is the lowest when the MPC concentration is 0.4M.(4)Study on Cu-MAA coatings prepared at different concentration of methacrylic acid(MAA),it was found that the content of copper gradually increased with the increase of the concentration of MAA,and the content of copper did not increase significantly when the concentration of MAA reached 0.6M.(5).Study on the molar ratio of MPC to MAA in solution,it was found that the content of Cu in copper 2-methacryloyloxy-ethyl phosphorylcholine/methacrylic acid(Cu-MAA/MPC)composite coatings increased with the increase of MAA.Compared with the friction and wear of MAA/MPC composite coatings and Cu-MAA/MPC composite coatings in protein solution,the protein adsorbed on the wear marks of the copper-MAA/MPC composite coatings is more significant,and when MPC:MAA=1:1,the protein adsorbed on the wear marks of the copper-MAA/MPC composite coatings is the most.