Evaluation of multifunctional marine coatings enriched with organometallic biocides supported on ZSM-5 zeolite for biofouling prevention

There is significant concern regarding the biocides commonly used in commercial antifouling protection systems because of their high concentrations in coastal areas and the potential harm they can cause to marine organisms. Thus, much research has been dedicated to replacing these biocides with environment-friendly alternatives. Particularly, the use of natural products that inhibit the settlement of fouling organisms is the key to antifouling coating technology. The purpose of this study was to develop antifouling paints by using eco-friendly compounds and implement a multifunctional coating factor. Natural-origin biocidal agents, such as capsaicin, and a copper-ion release system supported on synthetic zeolite ZSM-5 were used. The formulations resulted in viscosities and particle sizes similar to those of commercial antifouling paints. The capsaicin coatings exhibited less fracture damage and more resistance to deformation in the flexibility and cupping tests. In the adhesion tests, all formulations exceeded 3 MPa, thereby enhancing the adhesion values of conventional antifouling agents. However, the capsaicin coatings exhibited less abrasion resistance than those containing zeolite. Corrosion resistance tests using electrochemical impedance spectroscopy indicated good anti-corrosive properties, particularly in the coatings with 8 % and 10 % copper. All formulations proved to be bactericidal within 6 h, and some completely eliminated the cell density by 3 h, highlighting the effectiveness of the biocide against the marine strain Pseudoalteromonas sp. UCO92.