Study on biotribological properties of UHMWPE grafted with MPDSAH

In order to prolong the service life of artificial joints, a zwitterion monomer of MPDSAH ((3-(methacryloylamino)propyl)dimethyl (3-sulfopropyl)ammonium hydroxide) was grafted onto ultra-high molecular weight polyethylene (UHMWPE) powders to construct a brush-like structure by UV irradiation, and then the grafted UHMWPE powders were hot pressed as the bulk materials. The wettability of bulk materials surface with different monomer concentrations was analyzed. The tribological properties of modified UHMWPE bulk materials were investigated under distilled water and saline by sliding against stainless steel ball. The measurement of Fourier-transform infrared (FT-IR) spectroscopy indicates that MPDSAH is successfully grafted onto the surface of UHMWPE powders by UV irradiation. The contact angles of modified UHMWPE are decreased and the surface wettability is effectively improved. The friction coefficient of the modified sample is lower than that of untreated UHMWPE in aqueous lubricants during a long-term friction. With the increase of monomer concentration, the wear rate of grafted UHMWPE decreases gradually in distilled water. The grafting hydrophilic macromolecule polymer is helpful to form a lubricating film of water, which leads to the improvement of the lubricity of UHMWPE.