Self-cleaning and antibacterial polyurethane coatings with ZrO₂-Ag hybrid nanoparticles

This work explores how ZrO2-Ag nanohybrids can contribute the antibacterial and self-cleaning abilities to the acrylic polyurethane (PU) coatings. Firstly, ZrO2-Ag hybrid nanoparticles have been synthesized by seed-mediated growth methods. These ZrO2-Ag nanoparticles were then incorporated into the PU coating (at 2 wt.%). The experimental results showed that addition of ZrO2-Ag nanoparticles into the PU coating improved its mechanical properties. Its impact strength rose from 175 to 190 kg.cm, whereas abrasion resistance increased from 137.5 L/mil to 195.4 L/mil and relative harness increased from 0.82 to 0.92. The antibacterial study showed that after 24 h the number of E. coli viable cells was 6.3 x 10(3) CFU/cm(2) on the surface of PU/ZrO2 coating, whereas no viable cells were observed on the surface of PU/ZrO2-Ag coating. Self-cleaning study on the dirty PU-based coatings has been examined with both methylene blue (MB) and artificial dirty (AD) mixture under UV exposure. In the case of MB contaminant, the obtained data indicated that the PU/ZrO2-Ag coating has clearly degraded MB after 12 h of UV irradiation. In the case of the AD contaminant, after 192 h of UV exposure, 65.5% of the AD has remained on the surface of PU/ZrO2 coating, whereas in the presence of ZrO2-Ag hybrid nanoparticles, 32% of the AD has attached on the PU/ZrO2-Ag coating.