Study Of Hydrophilic Modification Of Methyl Vinyl Silicone Rubber Surface And Its Anti-bacterial Adhesion Properties

Silicone rubber had been paid more attention and widely used in the biomedical field because its some excellent characteristics, such as non-toxic, non-allergenic, high transparency, good biocompatibility and so on. However, the defects like low surface energy and poor hydrophilicity of silicone rubber surface limited it been better and more widely used. In this work methyl vinyl silicone rubber(MVQ) surface was irradiated by a high-energy vacuum ultraviolet(VUV) light to generate reactive sites. Then chitosan and its derivatives, sulfoammonium zwitterionic were grafted on silicone rubber surface with covalent bond by chemical grafting and UV grafting reaction respectively, thereby the hydrophilic properties of the silicon surface was improved. The anti-bacterial adhesive propertie of modified silicone rubber surface was also studied. The study found that:(1) The water contact angle on the surface of original silicone rubber was 102.5°, then its surface became completely wet and hydrophilicity was greatly improved by irradiated 200 s with 172 nm Xe2* vacuum ultraviolet light. However the activated silicone rubber surface contact angle became 94.3° in a natural environment after 120 h and the surface from hydrophilic into hydrophobic;(2) The C2 amino group in chitosan was protected from the reaction between benzaidehyde and chitosan to form chitosan Schiff-base, then C6 hydroxyl group was grafting quaternary ammonium salts side chain by nucleophilic substitution reaction and synthesizing water-soluble quaternized chitosan reserved reactive C2 amino group. With the reaction of amino group of chitosan derivative and silanol group of activated silicone rubber, chitosan or its derivative was successfully grafted on the surface of the silicone rubber by chemical bonds. The contact angle was 67.2° and 54.8° respectively. The modified silicone rubber surface could keep long-term retention of hydrophilic. Its surface contact angle was still only 81.8° and 69.7° respectively after placing the natural environment 168h;(3) Betaine zwitterionic monomers were successfully synthesized by nucleophilic substitution reaction of 1,3-propane sultone(PS) and N-(3- dimethylaminopropyl) methacrylamide(DMAPMA). Sulfoammonium zwitterionic was successfully grafted on silicon rubber by using UV grafting reaction. We found the best reaction condition was that the zwitterionic monomer concentration was 8wt%, photoinitiator concentration was 4wt% and the UV-curing time was 20 min, its surface contact angle was 38.5° and its hydrophilicity was significantly improved. Modified surface had better retention of hydrophilic and its contact angle only had 66.9° in the natural environment with 168h;(4) The silicone rubber samples which surface grafting on chitosan derivatives, sulfoammonium zwitterionic were exposed to Escherichia coli(E. coli) and Staphylococcus aureus(S.Aureus) for 24 h respectively. The modified surface exhibited good anti-bacterial adhesion properties and significantly reduced the number of adherent bacteria. At the same time the anti-bacterial adhesion properties of modified silicone rubber surface against S. Aureus was superior to E. coli.