Polypropylene film surface was grafted with amino groups by using a radio-frequency glowing discharge system fed with ammonia. The number of the surface amino groups was amplified by bonding tris-(2-aminoethyl)amine through the linker of 1,6-diisocyanatohexane. Phosphorylcholine (PC) bearing aldehyde functionality was covalently bonded with the surface amino group by reductive amination. Surface composition was determined by X-ray photoelectron spectroscopy (XPS). The grafted PC groups can cover 20%～40% of the surface. The success of the modifications was also supported by attenuated-total- reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and dynamic contact angle measurements. These methods of surface amino amplification and the subsequent coupling of PC-containing aldehyde molecules are promising ways of obtaining novel biomaterials.

Key words: phosphorylcholine, reductive amination, surface amino amplification, biocompatibility, polypropylene film