Grafting of maleic anhydride/styrene onto PVDF porous membrane was performed in the presence of supercritical carbon dioxide(SCCO2)as a solvent and swelling fluid．The copolymer of maleic anhydride and styrene (SMA) was grafted onto the out and inner surface of PVDF pores membrane by passing through the membrane pores

which was confirmed by ATR-FTIR and XPS measurements．The SEM photographs of the greedmembrane showed that the membrane structure was hardly changed

except for some jams of the out surface．It was found that the water contact angle of the out surface was reduced more than the inner surface．Themembrane biocompatibifity correspondingto protein adsmpfionwasimproved significantly with the grafting of SMA ontothe surface of the PVDF membrane．The effects of SCCO2 pressure and the comonomer and initiator concentrations were invesgated．