A Bioinspired Superhydrophobic Coating with Permanently Anchored Quaternary Ammonium Salts for Long-Lasting Antibacterial Protection

Abstract Microbial contamination of surfaces in food processing, healthcare, and daily life poses serious threats to public health. Conventional antibacterial coatings suffer from two intrinsic limitations: leaching of active biocides and rapid fouling by organic matter, which shield the killing groups from bacteria. Here we report a durable antibacterial coating that overcomes both drawbacks through a synergy of chemical bonding and self-cleaning. Quaternary ammonium groups are covalently grafted into an epoxy coating, and a hierarchical micro-/nanotexture is created using fluorinated tetrapod-like zinc oxide whiskers (T-ZnOw). The resulting coating exhibits a water contact angle (WCA) of 159.0° and a sliding angle (SA) of 2.5°, enabling roll-off of contaminating liquids and particulates. Even after 24 h of acid/alkali resistance test and 96 h of accelerated aging test, the coating still exhibits a water contact angle higher than 151°. The anchored quaternary ammonium salts show 47.6% lower migration than physically blended counterparts, while the superhydrophobic surface prevents biofilm formation. The coating exhibits an antibacterial efficacy of >99.9% against both Escherichia coli and Staphylococcus aureus within 2 h and maintains high activity even after heavy soiling. This design provides a general strategy for creating long-lasting, self-cleaning antimicrobial surfaces for food equipment, packaging, and medical devices.