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Present investigation demonstrates a very simple seed-mediated route for the synthesis of silver nanorods in aqueous solution. Central to the concept of seed-mediated growth of nanoparticles is that small nanoparticle seeds serve as nucleation centres to grow nanoparticles to a desired size and shape. Hydroxypropyl methyl cellulose (HPMC) has been used as soft template for one-dimensional growth of silver particles. Morphological, structural and spectral changes that are associated with the seed-mediated growth of the nanoparticles in presence of HPMC are characterized using UV-vis and HR-TEM spectroscopic study. Simulation of UV-vis extinction spectra of our synthesized silver nanorods has been carried out using discrete dipole approximation methodology. The broad red-shifted longitudinal extinction band of green-coloured silver sol has been explained, due to the presence of silver nanorods of different aspect ratios. [ABSTRACT FROM AUTHOR]

Abstract: We report a method to synthesize silver nanoparticles of varying morphologies by a seeding growth approach at room temperature. Seeds are prepared by reducing silver nitrate with sodium borohydride, and trisodium citrate is used as capping agent. This citrate capped seed sol is added to the growth solution containing ascorbic acid, sodium dodecyl sulphate (SDS) and sodium hydroxide. Colour of the growth solution changes from colourless to pink and the surface plasmon resonance (SPR) shows two distinct bands, indicating the formation of anisotropically grown silver nanostructures. Synthesized silver nanoparticles are characterized by UV–vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. Silver nanoseeds are spherical in shape with diameter ranges from 8 to 16nm. On the other hand, a mixture of morphologies with shapes like triangular and hexagonal nanoplates, nanorods are obtained in the growth solution. XRD results suggest that the particles are crystalline in nature with face centered cubic (fcc) geometry. [Copyright &y& Elsevier]