Enzymatic waterborne polyurethane towards a robust and environmentally friendly anti-biofouling coating

Abstract

A novel anti-biofouling coating was designed and prepared by directly mixing antifouling enzymes (lipase or protease) with a castor oil-based waterborne polyurethane (WPU) dispersion. Covalent incorporation of the enzymes into the WPU coating was realized via the reaction of the excessive NCO groups in WPU and the NH₂ groups in the enzyme molecules as investigated using enzyme leaking and IR analysis. The incorporation of the enzymes had a plasticization effect on the WPU coating, e.g. the tensile strength decreased and elongation at break increased after addition of lipase to the WPU coating. SEM images and contact angles (CAs) analysis showed that the enzymes were evenly distributed in the coating surface. The enzymatic WPU coatings displayed robust catalytic capabilities, e.g. 70% initial activity after ten continuous usages, ca. 50% initial activity after storage at room temperature for 90 days and ca. 20% initial activity after incubating at 60 °C for 90 days were obtained for the WPU coating containing lipase. Additionally, the enzymatic WPU coating afforded a self-cleaning ability against lipid and protein stains. This robust and environmentally friendly enzymatic WPU coating may provide a new strategy for resisting biomolecular contaminations.