Antibacterial Metal Oxide Polymer Surfaces by RF Magnetron Sputtering

Through the increased use of plastics in everyday life it is of high interest to prevent the growth and spread of microbes on such polymer surfaces. Next to galvanic coating, physical vapour deposition by sputtering is one of the most important processes for the metallization of polymers, used in many different industries (e.g. packaging, product-design, electronic devices, et cetera). This work presents results of a research project which aims to establish PVD - RF magnetron sputtering for the antibacterial functionalization of plastic surfaces. The presented approach tries to create metal or metal-oxide based biocidal surface properties directly at the surface by means of plasma deposition. Therefore, a large number of different polymers (e.g. PS, PE, PA6, PP, ABS) are coated with a thin film of the following metal oxides: Zn, Cu, Mo, W, etc. In particular, a RF magnetron sputter system (13,56 MHz) is used to deposit thin metal oxide films in a low pressure Ar plasma environment, at approximately 8 mTorr. The used discharge power is 800 W constant and 3000 W in pulsed mode. The application step just takes a few seconds. The according biocidal effect is evaluated afterwards by microbiological analysis. Additionally, the resulting physical surface properties are characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM-EDX), FT-IR/ATR-spectroscopy, etc. Special focus is also put on the solubility and adhesive properties of the coating.