Preparation and characterization of nano-sized Ag/PVP composites for optical applications

A modification of the polyol process has enabled the direct synthesis of nm-sized Ag particles with narrow size distribution and controlled average dimension embedded in a polymeric matrix. Dispersion of colloidal silver was obtained by reduction of silver nitrate in ethylene-glycol in the presence of a polymeric protective agent (i.e., poly(N-vinylpyrrolidone)) and ultrasounds. The final particle size was controlled by removing the colloid from the reactive mixture by addition of acetone. The very strong plasmon resonance peak at 410 nm and a feature at 350 nm in the UV-visible spectra are a clear consequence of the nanosize of dilute Ag particles. The proposed process offers the possibility to effectively use these synthesised materials for the production of colour filters for advanced optical devices.