Preparation of antibacterial surfaces by hyperthermal hydrogen induced cross-linking of polymer thin films

The covalent immobilization of polymers on surfaces has the potential to impart new properties and functions to surfaces for a wide range of applications. However, most current methods for the production of these surfaces involve multiple chemical steps or do not impart a high degree of control over the chemical functionalities at the surface. Described here is the preparation of surfaces covalently functionalized with quaternized poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), a known antibacterial polymer. PDMAEMA was coated onto octadecyltrimethoxysilane modified silicon wafers and was then cross-linked by the selective cleavage of C–H bonds using a hyperthermal hydrogen treatment. The surfaces were then quaternized with ethyl bromide. At each step the surfaces were characterized extensively using techniques including atomic force microscopy, contact angle measurements and X-ray photoelectron spectroscopy. These results demonstrated a high degree of functional group retention throughout the process. The antibacterial properties of the surfaces against Gram-positive S. aureus and Gram-negative E. coli were investigated using a “drop test” assay. Furthermore, the process was successfully applied to produce antibacterial butyl rubber surfaces, demonstrating the versatility of the method for grafting onto unfunctionalized hydrocarbon surfaces.