Authors: A. Mishra, P. Tripathy, S. Ram, H.-J. Fecht
Affilation: Indian Institute of Technology, India
Pages: 487 - 490
Keywords: nanoparticle, PVP polymer, Metal- polymer nanocomposites, XPS
Gold nanoparticles are synthesized by direct reduction of an aqueous solution of the metal salt with a surface regulating polymer N-polyvinyl pyrrolidone (PVP), which bind on the gold surface, insulate the particles from Au3+ and further aggregation. Varying the Au-content up to 1.0 wt% optimizes optical density in surface plasmon bands from the Au- nanoparticles of core-shell structure in conjunction with the surface polymer molecules. Au-metal particles modify the polymer structure in PVP. The Au-polymer surface interface seems to be one of the sensitive chemical parameters, which are responsible for the variation in the electronic, optical and other derived properties using a function of the Au-content. Studies on the nature of the microscopic interaction between Au particles and PVP polymer chains are important in understanding the Au-PVP hybrid composite system. In the Au-PVP system, changes in O1s photoemission confirm the microscopic interaction of the group with Au particles. It is analyzed with XPS spectrum that the binding energy in the Au 4f7/2 peak shifts to a lower value 83.1 eV relative to the bulk value 84.0 eV confirming the microscopic interaction between the Au nanoparticles and the PVP polymer in the hybrid composites. The XPS confirms that PVP molecules exist on the surface of the Au cores, which play a very important role in the formation and evolution of the different shape and size of the of the Au nanoparticles, e. g, twinned Au plates, polyhedral plates, truncated triangular shaped particles. Based on the experimental results, a growth mechanism is suggested to elucidate the formation of the small decahedral Au nanoparticles. Results are analyzed in correlation with microstructure and optical properties of Au-PVP hybrid nanocomposites prepared under selective experimental conditions.