Contact Angle Of Bionic Structure Surfaces And Wettability Of Chemical Modification Medical Polymers

As the higher performance requirements for clinical medical device, the performance with good anti-encrustation becomes the major demand. According to the microstructure of lotus leaf surface with super-hydrophobic and self-cleaning function, the design and preparation of medical polymer material surface with hydrophobic were researched in this paper. From the hydrophobic perspective, the anti-encrustation of biomedical materials was discussed. Major research works and the results are as follows:1. First, the wetting mechanism of solid-liquid interface and contact angle models were studied, including the relations between surface tension, surface energy and wettability. Five kinds of contact angle models were analyzed, as Young, Wenzel, Cassie, Cassie-Baxter, Wenzel-Cassie mode. Further, the switching mechanism of Cassie/Wenzel (C/W) wetting mode was studied.2. Some bionic structures were designed as regular microstructures, micro/nano structures, fractal structures, and whose contact angle models were put forward. The effects of interfacial energy, microstructure to the wettability were analyzed. The contact angles of microstructures are micro/nano structures, fractal structures regular microstructures form large to small in turn. In addition, the conditions of four microstructure surfaces to prevent the switching of C/W wetting mode were discussed.3. The chemical coarsening was used to form micro rough structure in polymer surface. The influences of processing parameters to coarsening effect were studied. The results show that the coarsening help to improve the surface contact angle of polyurethane and enhance the hydrophobic property.4. Chemical method was used in the preparation of nano-silver on medical polymer surface. Silver nitrate as mainly salt, PVP as dispersant, ammonia as Complex , ethanol as stabilizing agent, and sodium hypophosphite, glucose and potassium sodium tartrate were used three different reducing agent. Nano silvers with the uniform diameter of 20～50nm were prepared. The impacts of the main salt concentration, mixture ratio, reaction temperature, reaction time and other factors to chemical silvering on the surface of polyurethane materials were discussed. Then, the best nano-silver plating processes were achieved. The contact angle of polyurethane surface was increased form 115°to 135°. With the larger scale of the coarsening microstructure and nano-scale silver structure, the contact angle becomes greater, which is consistent with biomimetic structure model.5. The chemical roughening and chemical plating nano-silver were used for medical polyurethane stent catheters, and whose performances of anti-encrustation were tested and analyzed. The results show that chemical modification can effectively inhibit the formation of crust and than better the anti-encrustation performance than conventional stent because of the role of the anti-bacterial property of nano-silver and hydrophobic micro/nano structure by chemical modification.The researches are helpful for improving the anti-encrustation performance of biomedical materials, and provide the theoretical basis to the design and preparation of the hydrophobic surface.