Antifouling efficiency of polymer coatings with SeNPs-loaded SiO2(rh)-PHMG composite as antimicrobial agent

Silica from rice husk [SiO₂(rh)] was used as a mineral base for sequential loading of biogenic selenium nanoparticles (SeNPs) and polyhexamethylene guanidine (PHMG) hydrochloride. As result a filler for polymer coatings with a wide spectrum of antifouling activity was obtained. The complex filler was characterized by scanning electron microscopy, energy dispersive X-ray analysis, and transmission electron microscopy. The filler was introduced into epoxy (EP), polydimethylsiloxane (PDMS), and epoxy-siloxane (EP-PDMS) polymer matrices at 3 wt% and 5 wt% to evaluate their antifouling performance and effect on the durability characteristics of coatings. Characterization of the coatings was performed including water contact angle, surface free energy, pseudo-barnacle adhesion strength and modulus of elasticity. The in vitro antimicrobial properties of the prepared samples were evaluated using Staphylococcus aureus and Candida albicans. Antifouling properties were evaluated in field tests for 7 months. The incorporation of a complex filler involving SeNPs and PHMG made it possible to increase the coating resistance to fouling by 2–5 times. The best results were observed for the EP-PDMS sample with 5 wt% SiO₂(rh)-SeNPs-PHMG characterized by low values of surface free energy (10.3 mN/m) and pseudo-barnacle adhesion strength (0.32 MPa) and acceptable rate of biocidal components release. The results indicate the promising use of the new filler for development of effective antifouling coatings.