Synthesis of Ag@SiO2 core-shell nanoparticles for antibacterial application in water-based acrylic polymer coatings

In this study, Ag@SiO2 core-shell nanoparticles were synthesized using the Stöber method and then physically mixing with MPS functionalized poly (styrene-co-acrylate) (PSA) emulsion to obtain a novel antibacterial composite material (PSA/Ag@SiO2). The dispersion of composite latexes was improved by the formation of Si-O-Si covalent bonds, and the migration of AgNPs on the surface of composite films enhanced their antimicrobial activity. Analysis of UV-Vis absorption spectra, TEM images, XPS and XRD data confirmed the core-shell structure of Ag@SiO2 and the successful coating of AgNPs by SiO2. TEM micrographs showed that Ag@SiO2 core-shell nanoparticles were uniformly dispersed in the composite latexes, with an average particle size of 198 nm for PSA/Ag@SiO2 composite latexes, larger than that of PSA latexes (162 nm). FTIR spectra also indicated the presence of Si-O-Si covalent bonds resulting from the sol-gel reaction between MPS functionalized PSA with Ag@SiO2. XPS and WCA characterization revealed the disruption of the core-shell structure of Ag@SiO2, leading to the migration of AgNPs to the air-film interface. The results of antibacterial activity demonstrated that PSA/Ag@SiO2 composite films displayed antibacterial activity against both E. coli and S. aureus, and the former displayer a slightly better antibacterial activity than the latter. The water-based acrylic polymer coatings with antibacterial properties explored in current work have various applications in wood paints, varnishes, metal protection, decorative systems and other related fields.