Antimicrobial activity of silver free powder coatings based on biocomponents

In this work, silver-free, low-temperature-curing epoxy powder coatings with antimicrobial functionality were developed. The cationic biopolymer ε-polylysine (PLY) in its protonated form, as well as its intercalation and co-intercalation products with aminododecanoic acid (ADA) in montmorillonite (MMT), were employed as environmentally friendly bioactive additives. The powder coatings were formulated using epoxy resin and a highly reactive phenolic curing agent and subsequently applied onto steel substrates. The resulting materials were comprehensively characterized in terms of surface morphology, gloss, hardness, adhesion, and wettability. The coating showed a water contact angle of approximately 85°and an antibacterial reduction exceeding 99% against E. coli and S. aureus under laboratory conditions (ISO 22196). Antimicrobial activity is most likely associated with electrostatic interaction between the cationic PLY and bacterial membranes. Overall, this study suggests a promising and sustainable, silver-free strategy for developing antimicrobial powder coatings that may be suitable for hygiene sensitive environments, pending further long-term and safety evaluation.