| With the rapid development of modern material science, life science and medical science, different kinds of biomaterials have been widely used in clinical fields. Plasma surface modification of biomaterials has recently become a hot topic in materials design. Of which, one way is to improve the hydrophobic property of the film surface.Diamond-like carbon (DLC) and amorphous carbon films have been proposed as potential biomedical coatings due to their chemical inertness, low coefficient of friction, high wear resistance, and moderate biocompatibility. Fluorinated amorphous carbon films have successfully used in biomedical devices like electrosurgical tools due to their high hydrophobicity, good water-proofing, anti-adherence of the bacteria and good mechanical properties. Fluorinated amorphous carbon films with different fluorine content may have diamond-like and polymer-like structures, and the transition of hydrophobicity from moderate to high. Thus to make a detailed study between the film's structure and properties is of much importance.In this paper, three series of fluorinated amorphous carbon films with different fluorine to carbon were fabricated by plasma enhanced chemical vapor deposition (PECVD) and by plasma immersion ion implantation and deposition (PIII-D). Film composition, structure and properties were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), Raman scattering spectroscopy (Raman), atomic force microscopy (AFM). Hardness and scratch resistance were measured by nano-indentation and nano-scratch, respectively. Water contact angles were measured by sessile drop method. The influence of processing conditions (gas flow ratio, substrate bias voltage, C F4 flow) on the film's structure and properties wereespecially concerned.The results of XPS and Raman measurement indicated that as the CF4 inlets increasing, fluorine content was gradually increased to the film deposited by PECVD and PIII-D technique and the film structure was transited gradually from diamond-like to polymer-like. But the opposite behavior can be encountered with the further negative bias voltage and the constant ratio of 2/3, CF4 to CHU by PECVD.The results of contact angles show that evident improvements of the hydrophobicity have been made to these films due to the formation of hydrophobic groups -CFX (x=1,2,3) , with contact angles of double-stilled water (105) approaching that .of polytetrafluoroethylene (PTFE, 110 ). However, evident improvements of hydrophobic properties cannot be achieved only by the variation of the substrate bias voltage in a low range, as indicated by the contact angles.The optical gap E increases with raising the amount of fluorine but decreases as the amount of C =C bonding increased. This is because of the decrease hi the amount of n bonding formed by C =C and the increase in that of o bonding formed by C-F. As a result, the density of state near band edgy, o - o * increases and the optical gap becomes wide.The consistent downtrend of both the film hardness and the scratch resistance illustrates that the addition of fluorine to the amorphous carbon films crucially affects the mechanical properties. It is believed to be due to the fact that introduction of fluorine breaks cross-linked C-C bond and the sp3 diamond-like matrix collapses and the sp2 hybridizated carbon domains increases in the fiuorinated films. The films deposited by PIII-D have fairly good mechanical and hydrophobic properties than the films synthesized by PECVD.The study of platelet adhesion in vitro suggested that the percentage ofundistorted platelets adhering on the a-C:F(:H) surface is comparative to LTIC, but the total number of platelets adsorbing on the a-C:F(:H) surface clearly more than on the a-C:H and LTIC. The film deposited by PECVD, with diamond-like structure and higher fluorine content, may have a moderately better blood compatibility. However, the platelet did aggregate and distort worse on the super hydrophobic a-C:...
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