Preparation of antibacterial polymer-grafted nano-sized silica and surface properties of silicone rubber filled with the silica

Antibacterial polymer was grafted onto nano-sized silica surface and the surface properties of silicone rubber filled with the silica were investigated. The grafting of antibacterial polymer was carried out by two-step reactions as follows. Poly(p-styrene sodium sulfate) (poly(St-SO3-Na+)) was successfully grafted onto nano-sized silica surface by the radical polymerization of St-SO3-Na+ initiated by the system consisting of trichloroacetyl groups on the silica surface and MO(CO)(6): trichloroacetyl groups were introduced onto the silica surface by the reaction of amino groups with trichloroacetyl isocyanate. The percentage of poly(St-SO3-Na+) grafting increased with progress of the polymerization and reached about 30%. The poly (St-SO3-Na+)-grafted silica was treated with tributyltetradecylphosphonium chloride (Bu3RP+Cl-) to convert the SO3-Na+ groups to alkyl phosphonium salt, SO3-P+Bu3R, groups. The grafting of poly(St-SO3-P+BU3R) onto the silica surface was confirmed by IR spectra. The poly(St-SO3-P+Bu3R)grafted silica gave a stable dispersion in DMSO and poly (dimethyl siloxane). It was found that silicone rubber filled with the poly(St-SO3-P+Bu3R)-grafted silica shows extremely strong antibacterial activity. The silicone rubber surface has an ability to inhibit the reproduction of a Staphylococcus aureus and an Escherichia coli.