Influence of the molecular weight and concentration of PVP on the polyol synthesized silver nanoparticles

Abstract

In the present work the synthesis of silver nanoparticles by the polyol method is investigated. The self-seeding polyol process was chosen from the number of variations of this method. In this approach AgNO3 was used as a precursor, poly (N-vinylpyrrolidone) (PVP) as capping agent and ethylene glycol as solvent and reducing agent. We investigated the influence of the molecular weight of PVP on the microstructure of the particles considering a polymer with molecular weight Mw = 58 and 360 K by changing the molar ratio of PVP/AgNO3 for both polymers. The molar ratios were varied from 0.5 to 2.5. The as prepared nanoparticles were characterized by microscopic and structural methods. The shape and the size distribution were characterized by Transmission Electron Microscopy. The crystal structure of the nanoparticles was studied by X-ray Diffraction and Selected Area Electron Diffraction. Due to their plasmonic properties, the silver nanoparticles find application for improvement of the efficiently of the solar cells, substrates for surface-enhanced Raman and florescence spectroscopies. All these applications require the frequencies of the localized surface plasmon resonance (LSPR) to appear at an exact position. Therefore we indicated the wavelength of the LSPR of the as prepared nanoparticles trough the absorbance spectra. A variation between 380 and 470 nm was observed.