Shape control synthesis of spheroid and rod-like silver nanostructures in organic-inorganic sol-gel composite

The synthesis of a variety of spheroid and rod-like silver nanoparticles in hybrid organic-inorganic sol-gel composite films was examined. The sol-gel matrix used in this work involves urethane terminated silica network which acts as a stabilizing and coupling agent and can complex with silver atoms through its secondary amine functionality and form stable colloid dispersions. The parameters determining the particles size and shape are the starting concentrations of silver ions, the coordination and reduction abilities of the solvent and the reaction kinetics and temperature. In this work the reduction process of silver ion was performed by DMF in sol-gel polyurethane precursor solution at two reaction temperatures: (a) 40 ^{{ring operator}}C and (b) reflux at boiling temperature. The effects of concentration and temperature of solution on the morphology and uniformity of silver nanorods were investigated by UV-VIS spectroscopy, SEM and TEM. Spheroid nanoparticles size was as 10-12 nm. Electron diffraction shows that all nanoparticles have a silver face-centered cubic crystal lattice. The silver nanoparticles obtained in composite films exhibit a strong characteristic extinction peak, due to surface plasmon resonance occurring nearly 420-440 nm.