Date of Award

12-2006

Degree Name

Doctor of Philosophy

Department

Chemistry

First Advisor

Dr. Subra Muralidharan

Second Advisor

Dr. Michael Barcelona

Third Advisor

Dr. Sherine Obare

Fourth Advisor

Dr. Dongil Lee

Abstract

Nanoparticles of gold derivatized with monolayers of thiocarboxylic acid ligands, core/shell nanoparticle composites of gold and silica, gold-glutathioneclusters, and titania nanoparticles were synthesized and their surface properties (extent of ligand coverage, net negative charge, and zeta potential) characterized by capillary electrophoresis as a function of pH, ionic strength, and dielectric constant for the first time. The hydrodynamic radii of thenanoparticles were determined by dynamic laser light scattering and used to calculate the net surface charge, extent of ligand coverage, and zeta potentials ofthe nanoparticles from electrophoresic mobilities. The ligand derivatized nanoparticles had similar hydrodynamic radius of about 20 nm which was twice the value determined by transmission electron microscopy. This indicated the possibility of the formation of multilayers of carboxylic acid groups on the surfaceof the nanoparticles. These nanoparticles had a surface ligand concentration of about 10 -12 moles/cm2 based on the net negative charge at a pH value of10.8 which only accounted for the solvent accessible groups and not all the ligand groups as the light scattering technique. In general the net negative charge and associated zeta potentials increased with pH due to an increasing number of carboxylic acid groups being deprotonated with pH. The net charge and zeta potential decreased with increasing ionic strength and decreasing dielectric constant due to the association of Na + ions with the carboxylate ions on the surface of the nanoparticles. The Au/SiO 2 and SiO2 /Au nanoparticles exhibited quite different behavior from each other as a function of ionic strength and dielectric constant, the former behaving more like a bulk material and the latter like the ligand derivatized gold nanoparticles. The behavior of gold glutathionenanoparticles was similar to the thiocarboxylic acid derivatized gold nanoparticles at different pH, ionic strength, and dielectric constant. Aggregates containing gold glutathione nanoparticles were identified by capillary electrophoresis at various ionic strengths and dielectric constants. New and novel synthetic routes to obtain monodisperse TiO 2 nanoparticles of average radii 101 nm (acid hydrolysis) and 63 nm (base hydrolysis) were developed. Thesenanoparticles were also characterized by capillary electrophoresis.

Comments

5th Advisor: Dr. Brian Tripp

Access Setting

Dissertation-Open Access

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