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Abstract It is believed that the blood compatibility of artificial material are greatly influenced by the material's surface properties. Henceforth, plasma-induced graft polymerization technique is employed to modify polyethylene surface properties with an aim to improve its blood compatibility. Methacryloxyethyl phosphate(MOEP) is used as the monomer in this study in order to incorporate phosphate functionalities onto PE surface. Oxygen plasma is used to active the substrate with the formation of surface peroxide groups. Oxygen pressure, duration of plasma and RF input power are varied throughout the study. It was found that the amount of surface peroxide group, determined by DPPH method, increases with oxygen pressure and RF input power , and decreases with duration of plasma. Then, the virgin PE and plasma-activated PE(500mtorr、25watts、10mins and 100mtorr、25 watts、5mins) were chosen for further MOEP polymerization reaction by 15min、2hr、4hr、8hr of UV irradiation.(0.01 wt% riboflavin was added into monomer solution , and nitrogen were bubbling for 30mins.) After polymerization, static contact angle, ATR-FTIR& ESCA analysis indicate the amount of grafted- MOEP increases with UV irradiation and the amount of surface peroxide groups. In vitro platelet adhesion studies have shown plasma-activated PE exhibited high level of platelet adhesion and activation. After MOEP was grafted onto PE surface, the number of adherent platelet increased slightly with the duration of UV irradiation. There were no significant change in the number of adherent platelet between 4 and 8 hours of UV irradiation. Furthermore, it was also found that the degree of platelet activation in MOEP-grafted PE was less than the plasma-activated PE. It seems that negative charge characteristic of phosphate functional group or its chemical structure plays some important roles for platelet adhesion and activation. 【key words】plasma-induced graft polymerization、MOEP、blood compatibility
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