Ozone-induced grafting was developed to improve the hemocompatibility of biomaterials based on low-density polyethylene (LDPE). An LDPE film was activated with ozone and graft-polymerized with N,N'-dimethyl(methacryloylethyl)ammonium propane sulfonate (DMAPS). The existence of sulfobetaine structures on the grafted film was confirmed by X-ray photoelectron spectroscopy and attenuated total reflection/Fourier transform infrared (ATR-FTIR). More DMAPS was grafted onto the LDPE film as the DMAPS concentration increased, as determined by ATR-FTIR. Static contact-angle measurements indicated that the DMAPS-grafted LDPE film had a significant increase in hydrophilicity. The blood compatibility of the grafted film was preliminarily evaluated with a platelet-rich-plasma (PRP) adhesion study. No platelet adhesion was observed on the grafted film incubated with PRP at 37 degrees C for 180 min. This new sulfoammonium zwitterionic-structure-grafted biomaterial might have potential for biomedical applications. (c) 2006 Wiley Periodicals, Inc.