Functional Au and Ag Nanoparticles in polymer Composites and Molecular Assemblies

Abstract

My Ph. D. thesis consists of three broad areas, which are focused on the synthesis, characterization and application of nanomaterials. The thesis is divided into four sections, with each section divided into appropriate chapter(s). Section A Chapter 1 1.1. Introduction This chapter contains an overview of studies related to synthesis of shape selective nanomaterials. It also contains a brief review of synthesis of multi-branched Au nanoparticles (NPs) and their potential application in future nanoscience and technology. Additionally, it also briefly outlined the importance of the functional nanomaterials and that can be subsequently used for the generation of polymer-metal NPs composites, which is having the high pontential impact for fabrication of nanodevice based application. Further, this section also has briefly summarized the molecularly controlled assembly of nanoparticles and their emphasis of controlling the properties of nanomaterials. Moreover, the brief summary of the work reported in thesis also has been discussed. Section B In this section, we describe a simple method of preparation of shape selective Au NPs by using Fe2+ as the reducing agent in the presence of various stabilizing agents. Chapter 2 2.1. Stabilizing Agent Specific Synthesis of Multi- branched and Spherical Au Nanoparticles by Reduction of AuCl4- by Fe2+ ions. Here, we report on the development of a new method of synthesis of Au nanoparticles (NPs) of muti-branched and spherical shapes. HAuCl4 when reduced by Fe2+ ions in aqueous solution, in the presence of sodium dodecyl sulfate (SDS), produced multi-branched Au NPs including a shape that could be termed as a DnanofanD. On the other hand spherical particles were produced in the presence of Na2S and SDS or starch (instead of SDS). UV-vis, X-ray diffraction, transmission electron microscopic (TEM) studies revealed the difference in optical properties and shapes under various conditions. The essential conclusion is that stabilizing agent and other reagents have special roles in controlling the shape of the NPs produced. .... Section C In this section, we discuss the development of a novel method for the generation of green chitosan-silver nanoparticles composite (Chi-Ag NPs), which is subsequently used in efficient catalysis for the reduction of 4-nitrophenol into 4-aminophenol. The composite could also be used for the selective C-C bond formation of phenolic coupling reactions. Further, the interaction of the thermoresponsive polymer hydrogel with different stabilizing agent capped Au NPs has also been reported in this section. This section has been divided into three chapters with each chapter containing introduction, experimental section, results and discussion and conclusion..