Valorization of novel bifunctional waterborne coatings with UV irradiation resistance and antimicrobial activity

This research aimed to create bifunctional acrylic waterborne coatings capable of absorbing UV radiation and resisting microbial growth. The compound 4-[2(3-acetylphenyl) diazenyl]-3,5-dimethylphenol (ADD) was incorporated into the waterborne acrylic resin at concentrations of 0.1%, 0.25%, and 0.5%. The coatings underwent characterization through scanning electron microscopy (SEM), mechanical property testing, and the CIELab color method after 500 h of UV exposure to assess their UV shielding effectiveness. Furthermore, the antimicrobial properties of both ADD powder and the coatings were evaluated against Gram-negative bacteria (Helicobacter pylori), Gram-positive bacteria (Staphylococcus aureus), and pathogenic fungi (Candida albicans) using the disc diffusion method. Results indicated that the coatings with 0.25% and 0.5% ADD retained their integrity, showing no cracks or color and texture changes after UV exposure. In contrast, the 0.1% ADD coating exhibited significant alterations in the a* value, revealing its susceptibility to UV damage and limited UV absorption. Positive a* values confirmed the red tint of the films. Antimicrobial activity was notable, with inhibition zones measuring 14 to 26 mm against Staphylococcus aureus, 11 to 21 mm against Helicobacter pylori, and 12 to 20 mm against Candida albicans. Overall, this study demonstrated that the developed coatings with ADD significantly enhance UV absorption and exhibit promising antimicrobial properties, effectively overcoming the limitations of existing commercial coatings and offering a viable solution for protecting surfaces from UV radiation and microbial contamination.