Synthesis and characterization of gold-based nanoscopic additives for polymers

A new chemical route for the synthesis of alkanethiol-derivatized gold clusters of controlled size to be used for polymer functionalization has been developed. Gold clusters were prepared by reduction of tetrachloroauric acid with ethylene glycol in presence of poly(N-vinyl pyrrolidone) (PVP) as stabilizer. PVP-protected gold clusters were separated from the reactive mixture by flocculation with acetone; then, they were dissolved in a dodecanethiol/ethanol solution to produce thiol-derivatized Au clusters. Passivated clusters were dispersed in polystyrene/chloroform solutions and high-transparent purple-colored nanocomposite films were obtained by solution casting. This preparative scheme allows to produce polymer-based high-quality optical filters with complete control over the absorption properties.