Surface Hydrophilic Modification Of Medical Catheter

Most of medical interventional catheters are fabricated by the hydrophobic material, such as polyurethane, silicon rubber and so on. Although they have excellent mechanical properties and biocompatibility, there is a larger friction on the organization. They are easy to damage the urethra, blood vessel wall and other epithelial tissues. They also easily absorb bacteria and cause inflammation. Therefore they need to improve the hydrophilicity. The present paper investigated the surface hydrophilic modification of medical silicone rubber and polyurethane catheter. We successfully prepared a PVP hydrophilic coating on the substrates by appropriate treatment and silane coupling agent. We optimized the technics of preparation by adjusting kinds of coupling agents and times of dipping in PVP hydrophilic.The surface morphology and the thickness of PVP coating were investigated using SEM (scanning electron microscope), and hydrophilic properties of the samples were characterized by water contact angle. The results showed that the coating treated by the coupling agent and then coated with hydrophilic solution was better than the coating coated with PVP hydrophilic solution directly. The thickness and surface roughness of the coating increased as the dipping times increased in PVP hydrophilic solution. For silicon rubber material, the performance of the coating was optimum which treated by KH792 and dipped 2 times in PVP hydrophilic solution. The surface of the coating was smooth and its surface contact angle dropped to 18°±3°. For polyurethane material, the coating's performance was optimum which treated by KH550 and dipped 2 times in PVP hydrophilic solution. The surface of the coating was also smooth and its surface contact angle decreased to 7.6°±3°.The tendency of hydrophilic coating in water was analyzed by measuring water contact angle of different samples with soaking time in water at 37℃. The results indicated that the hydrophilicity of the sample treated by coupling agent and dipped 2 times in hydrophilic solution was modified significantly, and the hydrophilicity soaking of modified samples in water 7 days was much better than that of the matrix. For silicon rubber material, the hydrophilicity of samples treated by KH792 was better than KH550, whose contact angle is less than 75°after soaking a week. For polyurethane material, the hydrophilicity of samples treated by KH550 was better than KH792, whose contact angle is about 50°after soaking a week in water.The functional groups of sample's surface were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) after coated with coupling agent and PVP hydrophilic solution. The results showed that the substrate's surface appeared obvious peaks, indicating that silane coupling agent and PVP coating better combined to the substrate. For both substrates, the strength of PVP characteristic peaks affected by silane coupling is consistent with the results of contact angles.