This work aims to explore how ZnO nanoparticles enhance the mechanical, photoaging, and self‑cleaning properties of water‑borne acrylic coating. Micro/nano‑ZnO particles (at 2 wt.% of total solid resin) were dispersed into the acrylic polymer matrices using ultrasonication to understand the effect of the size of the coating properties. The effect of ZnO particles on the properties of composite coatings (25 µm of thick) have been evaluated through various tests, such as abrasion measurement, ultraviolet/condensation (UV/CON) weathering aging, and methylene blue self‑cleaning. Experimental data indicated that the incorporation of ZnO particles enhanced both abrasion resistance and methylene blue removal efficiency of the water‑borne acrylic coatings, with nano‑ZnO particles being the best. However, the weathering degradation of nanocomposite coatings was more severe as compared to the coating with micro‑ZnO (at the same ZnO content).

The goal of this work is to study the antibacterial activity of acrylic polymer/ZnO–Ag nanocomposite coating. First, in the presence of UV light ([Formula: see text][Formula: see text]nm), Ag nanoparticles (NPs; derived from AgNO3 precursor) were photoreduced and deposited on the surface of nano-ZnO. Field emission scanning electron microscope (FE-SEM) images indicated that the AgNPs (5–15[Formula: see text]nm) were deposited on the surface of nano-ZnO (20–40[Formula: see text]nm). These ZnO–Ag nanohybrids (0.1–0.2[Formula: see text]wt.%) were incorporated into the acrylic polymer matrix using ultrasonication to form the nanocomposite coating ([Formula: see text][Formula: see text][Formula: see text]m thick). Nano-ZnO hybridized with AgNPs resulted in a decrease in the energy gap ([Formula: see text] of ZnO from 3.2[Formula: see text]eV to 2.7[Formula: see text]eV, as observed by diffused reflectance UV–Vis spectrum analysis. The abrasion resistance test indicated that the incorporation of hybrid NPs enhanced the abrasion resistance of the polymer coating (from 81 to 125[Formula: see text]l/mil). Moreover, the polymer nanocomposite coating showed high antibacterial efficacy against [Formula: see text]. coli and [Formula: see text]. aureus in antibacterial tests and achieved 1.8 and 1.2 log after 24[Formula: see text]h, respectively. These findings endorse that the ZnO–Ag nanohybrid-based water-borne nanocomposite coatings offer exceptional antibacterial efficiency and would be promising in this application.

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This study explores how hybrid nanoparticles can be used to improve the antibacteial properties of both single nanoparticles and their polymeric nanocomposite coatings. Hybridization of two different nanoparicles, such as nano‐ZnO and silver nanoparticles (AgNPs) has been carried out to combine advantages of the individual particles. For these purposes, firstly ZnO−Ag hybrid nanoparticles were chemically fabricated by reducing Ag+ precursor on the as‐received nano‐ZnO using sodium borohydride in aqueous medium. Thereafter, these ZnO−Ag nanohybrids were introduced into the acrylic polyurethane matrix (at 2 wt.%) under sonication in xylene/toluene solvents. To reveal the effect of hybridization on the antibacterial activity against E. coli of both ZnO−Ag nanohybrids and their nanocomposite coatings, two antibacterial tests have been carrieried out in presence of visible light irradiation or without light (in dark). The agar‐well diffusion method indicated that ZnO−Ag nanohybrids exhibited high antibacterial activity against E.coli at the low concentration (8 mg/mL). In addition, their larger inhibition zones under visible light exposure were observed, when compared to the dark condition. Similarity, antibacterial test (ISO 22196 : 2007 standard) indicated that nanocomposite coating under visible light exposure had a higher antibacterial activity than that in the dark condition. Data from this antibacterial test after 24 h indicated that the visible light exposure provided more bactericidal efficiency for APU/ZnO−Ag coating (4.17 log), as compared to the dark condition (4.07 log). This increase in the bactericidal efficiency can be attributed to the hybridization of nano‐ZnO and AgNPs in their hybrid nanostructure. From the experimental data, we propose the mechanism for antibacterial activity of ZnO−Ag hybrid nanoparticles. In addition, TEM photographs indicated that AgNPs (10–30 nm) were attached to the surface of nano‐ZnO (<100 nm). Data from the diffused reflectance spectra indicated that the deposition of AgNPs on nano‐ZnO reduced its band gap energy (Eg) from 3.2 eV to 2.75 eV. In case of nanocomposite coating, addition of 2 wt.% ZnO−Ag nanohybrids into the acrylic polyurethane matrix significantly increased their impact strength and abrasion resistance.

This work emphasizes to use silver decorative method to enhance the antibacterial activity of TiO2 and ZnO nanoparticles. These silver decorated nanoparticles (hybrid nanoparticles) were synthesized by using sodium borohydride as a reducing agent, with the weight ratio of Ag precursors: oxide nanoparticles = 1: 30. The morphology and optical property of these hybrid nanoparticles were investigated using transmission electron microscopy (TEM) and UV&ndash;vis spectroscopy. The agar-well diffusion method was used to evaluate their antibacterial activity against both Staphylococcus aureus and Escherichia coli bacteria, with or without light irradiation. The TEM images indicated clearly that silver nanoparticles (AgNPs, 5-10 nm) were well deposited on the surface of nano-TiO2 particles (30-60 nm). Besides, smaller AgNPs (&lt; 2 nm) were dispersed on the surface of nano-ZnO particles (20-50 nm). UV-vis spectra confirmed that the hybridization of Ag and oxide nanoparticles led to shift the absorption edge of oxide nanoparticles to the lower energy region (visible region). The antibacterial tests indicated that both oxide pure nanoparticles did not exhibit inhibitory against bacteria, with or without light irradiation. However, the presence of AgNPs in their hybrids, even at low content (&lt; 40 mg/mL) leads to a good antibacterial activity and the higher inhibition zones under light irradiation as compared to that in dark was observed.