Solventless hybrid grafting of antimicrobial polymers for self-sterilizing surfaces

Self-sterilizing surfaces were created using a single-step solventless grafting method. The grafting process was conducted by vapor deposition of a crosslinked poly(dimethylaminomethyl styrene-co-ethylene glycol diacrylate) (P(DMAMS-co-EGDA)) prime layer, followed by in situ grafting of poly (dimethylaminomethyl styrene) (PDMAMS) from the reactive sites of the prime layer. The hybrid coating allows both strong binding with the substrate and enriched bactericidal functionality on the surface. The atomic force microscopy (AFM) observation revealed dense granular structures on the coating surface at the initial stage of grafting and larger domains as the grafting proceeded. Live/dead viability assay showed disruption of bacterial membranes upon surface contact with the grafted coating. The hybrid grafted coating of P(DMAMS-co-EGDA)-g-PDMAMS had more than 99% bacterial killing against both Gram-negative Escherichia coli and Gram-positive Bacillus subtilis. The grafted coating exhibited durable bactericidal efficacy after continuous washing.