[Analysis of Grey correlation between surface energy and adhesive characteristic of platelet for DLC]

In this study, the diamond like carbon (DLC) samples made from different processes and processing conditions, were subjected to the test of platelet adhesion. The surface energy parameters such as surface tension, critical surface tension, interface tension, adhesive power, and polar branch and chromatic dispersion branch of surface tension based on determining balanced contact angle of ethanol, water and different ratios of ethanol/water solution on surfaces of the samples were calculated, respectively. Then the effects of these parameters on the amounts and deformation index of the platelets adhering to the samples were assessed by analyzing the T-type correlation degree in the Grey system. The results showed: (1) all degrees of correlation between surface energy parameters and adhesion amounts of platelet are positive, but for deformation index, the correlation degrees are negative except for critical surface tension; (2) the adhesion amounts of platelet increase with the rising polar branch of surface tension, while the deformation index increases with rising chromatic dispersion branch of surface tension; (3) Both adhesion amounts and deformation index of platelet are positively correlated with critical surface tension to a higher degrees; (4) the effects of polar branch of surface tension on adhesion amounts and deformation index of platelet keep pace with the surface tension, interface tension and adhesive power. Thus two important conclusions have been obtained: (1) the adhesive characteristic of platelets to the surface of DLC is closely related with the surface energy of DLC; the hemocompatibility of DLC is decided by the balance between the polarity of DLC surface and the limited humidifying water on the surface; there is a blood compatible range delimited by critical surface tension; (2) adhesion and deformation of platelets on surface of DLC have different energy mechanism: polar surface is advantageous to the adhesion, while the deformation is achieved with the aid of chromatic dispersion action stem from the surface.