We have used an alcohol reducing method of silver nitrate to prepare heterogeneous silver-silica nanocomposite particles with thiol and amino groups serving to bind the Ag nanoparticles to the surfaces of the SiO2 nanoparticles. We examined products of these reductions using transmition electron microscopy and UV-vis. spectroscopy. The SiO2 nanoparticles had diameters ranging from 70 to 90 nm; the Ag nanoparticles that formed on the surfaces of the SiO2 nanoparticles had an average size of ca. 15 nm. The dimensions of the Ag nanoparticles on the SiO2 surface were influenced by the molecular weight and concentration of polyvinylpyrrolidone (PVP) added to the reaction medium. In addition, the functional groups present on the surfaces of the SiO2 nanoparticles had a profound influence on the coverage by Ag nanoparticles. When NH2 groups were present on the surfaces of the treated SiO2 nanoparticles, the sizes of the deposited Ag nanoparticles increased upon increasing the PVP concentration; in contrast, increasing the molecular weight of the PVP decreased the average size of these Ag nanoparticles. The Ag-SiO2 nanocomposite prepared from SH-functionalized SiO2 nanoparticles exhibited different behavior.

Keywords: Silver-silica heterogeneous nanocomposite, Functionalizing agent, Thiol, amino, PVP.