Studies of Chemical and Photochemical Tuning of Selected Gold and Polymer Nanoparticle Systems

Abstract

Developingways to tune and control the non-compositional parameters such as the size, surface morphology, etc. of the nanomaterials is of paramount importance because a simple variation of such non-compositional parameters results innew material properties.New facile, faster, greener, and economicalmethodologies to manipulate materials at the nanoscale are the need of the day.Compared to the conventional size and shape-controlled synthesis of nanoparticles, the post-synthesis tuning of the size and morphology of the nanomaterials has been less explored.The thesis work involves studies of chemical and photochemical modifications of some selected gold/polypyrrole(PPY) nanosystems.Goldand conducting polymernanomaterials are a few of the most extensively studied nanomaterials systems due to their uniquepropertiesand wide-ranging promising applications. We have explored and demonstrated some simple, rapid,and practical chemical and photochemical methodologies for the controlled post-synthesis tuning of the size and morphology of diverse kinds of gold/PPYnanoparticlesystems. Thesemethodsare inexpensive and technologically simple to implementbecause they do not involve any hazardous chemicals, sophisticated equipment,or tedious process such as heating, continuous oxygen bubbling, maintenance of pH, etc. The roles of various reaction parameters and plausible mechanisms of the chemical and photochemicalmodifications have been investigated. The nanosystems have been characterized by techniquessuch as UV-visible-NIRand surface-enhanced Raman scattering spectroscopies,dynamic light scattering,transmission electron microscopy, scanning electron microscopy, thermogravimetry, circular dichroismspectroscopy, etc. The effects of the post-synthesis treatments of the gold/PPYnanosystems on surface-sensitive properties like catalysisand SERS have been studied. We have shownthat simple post-syn