Preserving the color of silver nanoparticles from solution into PVA films using silica coatings

Silver nanoparticles are a tiny but mighty innovation for the field of material science. Their unique properties make them a powerful tool for the development of optical sensors but controlling the color when embedding the particles into a useful matrix poses many challenges due to high sensitivity to changes in refractive index. Here we explored how silica shells can be used to encase silver particles and reduce the sensitivity to environmental changes. Using a Plackett-Burman experimental design, the critical parameter of the silica shell synthesis, the concentration of tetraethyl orthosilicate, was determined and used to tune the thickness of silica shells. When silica coated nanoparticles were embedded in polyvinyl alcohol, thicker shells led to smaller shifts of the localized surface plasmon resonance, thus preserving the color. This process helps to control changes in the λmax­ of silver nanoparticles, making them more effective choices for the development of optical sensors