Coating systems used for anticorrosion protection usually consist of a primer, intermediate layers, and topcoats. Zinc-rich primers, which serve as cathodic and barrier protection, are widely used for the corrosion protection of steel structures. Due to the fact that the functioning of the above-mentioned coatings is related to the conduction of galvanic current, these types of coatings are highly pigmented with zinc (up to 80 wt% in the dry coating). This may result not only in a deterioration of the performance of the coating system but also have a negative impact on the environment. Taking the above into account, solvent-based and water-based organic epoxy primers with zinc content reduced to approximately 50% have been developed. Zinc pigments of different shapes and with different surface treatments were used in the primers, as well as pigments without chemical treatment but with the addition of nanoparticles. It was found that, depending on the type of zinc pigment, both the developed solvent-based and water-based primers demonstrate good protective properties comparable to traditional zinc-rich coatings. Water-based paints tend to absorb more moisture compared to solvent-based systems, but their water uptake reversibility is limited. Moreover, the organic treatment of zinc flakes helps to improve this water uptake reversibility, improving the mechanical properties of coatings.

This article presents the results of research on UV-curable epoxy coatings developed with selected plant modifiers such as garlic (Allium sativum), turmeric (Curcuma longa), common nettle (Urtica dioica), and privet (Ligustrum vulgare). This study aimed to evaluate the influence of these natural components on the functional properties of UV-cured coatings and to assess their potential as bio-based modifiers. The coatings were formulated using Epidian^® 5 epoxy resin, a safe and non-toxic material approved for food-contact applications, and cured with a commercial cationic photoinitiator. Their mechanical, surface, optical, and antibacterial properties were investigated. The results showed that all plant-based additives modified both the mechanical and esthetic characteristics of the coatings; however, garlic demonstrated outstanding antibacterial activity, achieving nearly complete inhibition of Staphylococcus aureus growth with a reduction rate of 99.998%. These findings highlight that natural modifiers, especially garlic, can serve as highly effective functional components, while future work should focus on implementing these coatings for surfaces exposed to bacteria, such as public utility items and shop, hospital, sports, and rehabilitation equipment.

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.

This study presents an eco-friendly approach to antibacterial polyester powder coatings by incorporating hybrid additives composed of biopolymers immobilized on halloysite nanotubes. Polylysine (PLY) and quaternized chitosan (CH-Q) were used as natural antimicrobial agents, while halloysite (HAL) acted as a carrier to improve dispersion and reduce leaching. HAL/PLY and HAL/CH-Q hybrids were incorporated into polyester coatings and evaluated for morphology, mechanical properties, water resistance, and antibacterial performance (ISO 22196). The HAL/PLY coating demonstrated a strong bactericidal effect, reducing Escherichia coli and Staphylococcus aureus by 99.9989% and 99.9993%, respectively. HAL/CH-Q showed moderate activity against E. coli (50.2323%) but high activity against S. aureus (98.6500%). Immobilization of biopolymers on the halloysite surface improved dispersion and barrier properties while enabling a silver-free antibacterial effect. The results demonstrate a sustainable strategy for multifunctional powder coatings based on naturally derived antimicrobial components.