Preparation of Electro- and Magneto-Active Hybrid Nanocomposite Materials

Abstract

This dissertation describes the preparation and characterization of magneto and electro-active hybrid nanocomposite materials. In this research, two hybrid nanocomposite materials, gold-cobalt oxide nanowires and ferrocene functional polymer brushes on electrode surface, were investigated. Polymerizations of magnetic colloidal monomers to form electro-active nanowires and ferrocene functional monomers on electrode to form electro-active polymer brushes were demonstrated. The central focus of this research is utilizing colloidal polymerization and surface-initiated polymerization to prepare electro-active hybrid nanocomposite materials for potential applications in energy storage and conversion.Colloidal polymerization has been developed as a novel synthetic methodology to prepare 1-D mesostructures via dipolar assembly and chemical reaction. This method was exploited to synthesize multicomponent 1-D nanowires by using polymer-coated ferromagnetic gold-cobalt core-shell nanoparticles as colloidal monomers. Prepared semiconductor cobalt oxide nanowires with gold inclusions exhibited enhanced optical and electrochemical properties compared to cobalt oxide nanowires. This research provided a platform in fabricating a wide range multicomponent semiconductor nanowires as new nanostructured electrodes for potential applications in energy storage and conversion. Further, self-assembled gold-cobalt core-shell nanoparticles were utilized to align novel gold nanoparticles on a substrate. This facile and template free approach enabled the linear and ring assembly of noble gold metal on a substrate.Indium tin oxide (ITO) thin films are key components as transparent electrodes in a number of optoelectronic devices. The modification of ITO surfaces with polymers via electropolymerization has been widely investigated to improve surface compatibility and charge injection from the interface. However, there remain challenges to prepare polymers possessing, well-defined interfacial chemistry, molecular weight, composition, and functionality. This dissertation provides a modular synthetic methodology to prepare ferrocene functional polymer brushes on ITO via surface-initiated atom transfer radical polymerization (SI-ATRP). This work provided a simple model study to enable direct electrochemical and topographic characterization of well-defined polymer brushes on ITO with controlled molar mass and composition. These ITO grafted polymer brushes are also a novel model system for optoelectronic materials, where the effect of chain alignment and morphology can be correlated with electrical and electrochemical properties.