Development and evaluation of self-polishing urethane coatings with tethered quaternary ammonium biocides

The synthesis and characterization of hydrolysable, antimicrobial cross-linked polyurethanes are described. Cross-linking of isocyanate-terminated urethane oligomers with glycol-modified silanes was used as a novel method for imparting enhanced mechanical integrity and hydrolytic potential to polyurethane coating systems. By combining these cross-linkers with a variety of biocidal quaternary ammonium salts and polyisocyanates, a library of hydrolysable polyurethanes were developed with controllable mechanical, thermal, hydrolytic, and antimicrobial properties. Up to a 3-log reduction of viable microbes was observed and correlated with the surface content of side chain quaternary ammonium salt moieties. Diminished antibacterial characteristics of completely amorphous systems are attributed to the segregation of low surface energy constituents at the material:air interface and relegation of biocidal species to within the bulk material.