University of Kentucky UKnowledge University of Kentucky Doctoral Dissertations Graduate School 2007 CHARACTERIZATION OF COLLOIDAL NANOPARTICLE AGGREGATES USING LIGHT SCATTERING TECHNIQUES Mehmet Kozan University of Kentucky, [email protected] Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Kozan, Mehmet, "CHARACTERIZATION OF COLLOIDAL NANOPARTICLE AGGREGATES USING LIGHT SCATTERING TECHNIQUES" (2007). University of Kentucky Doctoral Dissertations. 567. https://uknowledge.uky.edu/gradschool_diss/567 This Dissertation is brought to you for free and open access by the Graduate School at UKnowledge. It has been accepted for inclusion in University of Kentucky Doctoral Dissertations by an authorized administrator of UKnowledge. For more information, please contact [email protected]. ABSTRACT OF DISSERTATION Mehmet Kozan The Graduate School University of Kentucky 2007 CHARACTERIZATION OF COLLOIDAL NANOPARTICLE AGGREGATES USING LIGHT SCATTERING TECHNIQUES _____________________________________ ABSTRACT OF DISSERTATION _____________________________________ A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Engineering at the University of Kentucky By Mehmet Kozan Lexington, Kentucky Director: Dr. M. Pinar Mengüç, Professor of Mechanical Engineering Department Lexington, Kentucky 2007 Copyright © Mehmet Kozan 2007 ABSTRACT OF DISSERTATION CHARACTERIZATION OF COLLOIDAL NANOPARTICLE AGGREGATES USING LIGHT SCATTERING TECHNIQUES Light scattering is a powerful characterization tool for determining shape, size, and size distribution of fine particles, as well as complex, irregular structures of their aggregates. Small angle static light scattering and elliptically polarized light scattering techniques produce accurate results and provide real time, non-intrusive, and in-situ observations on prevailing process conditions in three-dimensional systems. As such, they complement conventional characterization tools such as SEM and TEM which have their known disadvantages and limitations. In this study, we provide a thorough light scattering analysis of colloidal tungsten trioxide (WO3) nanoparticles in the shape of irregular nanospheres and cylindrical nanowires, and of the resulting aggregate morphologies. Aggregation characteristics as a function of primary particle geometry, aspect ratio of nanowires, and the change in dispersion stability in various polar solvents without the use of dispersants are monitored over different time scales and are described using the concepts of fractal theory. Using forward scattered intensities, sedimentation rates as a result of electrolyte addition and particle concentration at low solution pH are quantified, in contrast to widely reported visual observations, and are related to the aggregate structure in the dispersed phase. For nanowires of high aspect ratios, when aggregate structures cannot directly be inferred from measurements, an analytical and a quasi- experimental method are used. KEYWORDS: Aggregation, Fractal Dimension, Small Angle Static Light Scattering, Elliptically Polarized Light Scattering, Sedimentation Rate Mehmet Kozan March 15, 2007 CHARACTERIZATION OF COLLOIDAL NANOPARTICLE AGGREGATES USING LIGHT SCATTERING TECHNIQUES By Mehmet Kozan Dr. M. Pinar Mengüç Director of Dissertation Dr. L. Scott Stephens Director of Graduate Studies November 27, 2007 RULES FOR THE USE OF DISSERTATIONS Unpublished dissertations submitted for the Doctor’s degree and deposited in the University of Kentucky Library are as a rule open for inspection, but are to be used only with due regard to the rights of the authors. Bibliographical references may be noted, but quotations or summaries of parts may be published only with the permission of the author, and with the usual scholarly acknowledgements. Extensive copying or publication of the theses in whole or in part also requires the consent of the Dean of the Graduate School of the University of Kentucky. A library that borrows this dissertation for use by its patrons is expected to secure the signature of each user. Name Date ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ DISSERTATION Mehmet Kozan The Graduate School University of Kentucky 2007 CHARACTERIZATION OF COLLOIDAL NANOPARTICLE AGGREGATES USING LIGHT SCATTERING TECHNIQUES _____________________________________ DISSERTATION _____________________________________ A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Engineering at the University of Kentucky By Mehmet Kozan Lexington, Kentucky Director: Dr. M. Pinar Mengüç, Professor of Mechanical Engineering Department Lexington, Kentucky 2007 Copyright © Mehmet Kozan 2007 To Bilge… ACKNOWLEDGEMENTS I would like to thank my dissertation director Professor M. Pinar Mengüç for the visionary researcher spirit he so enthusiastically shared, the financial support he provided, his patience, and his comments and reviews during the writing of this dissertation. Financial support of the Scientific and Technical Research Counsel of Turkey (TUBITAK) which lasted for two years is also gratefully acknowledged. Thanks also to my dissertation committee including Professor Kaveh A. Tagavi and Professor Dusan P. Sekulic of UK-Mechanical Engineering Department, Professor Czarena Crofcheck of UK-Department of Biosystems and Agricultural Engineering Department, Professor J. Todd Hastings of UK-Electrical Engineering Department, and Professor Mahendra K. Sunkara of University of Louisville Chemical Engineering Department for serving in my committee and their valuable comments. I would like to thank Professor Sunkara also for his rewarding collaboration on characterization of the nanomaterials synthesized in his lab, and Jyothish Thangala and Rahel Bogale of his research team for preparing the nanomaterials and corresponding SEM images. This dissertation, while an individual work, benefited from the experimental setup that was built or improved by former graduate students and post-doctoral fellows of Professor Mengüç. Among them Dr. Mustafa Aslan who re-built the setup and shared his expertise generously is gratefully acknowledged. Thanks also to Dr. Sivakumar Manickavasagam for making his broad expertise on the experimental setup always available and for his technical support. The first compact version of the bench-top prototype I took some part in building, has now passed some critical stage in reaching the market—thanks to the efforts of Dr. Manickavasagam, as well as of Professor Mengüç. The discussions with Dr. Rodolphe Vaillon of INSA, Lyon, his insights and encouragement have been invaluable at various stages of this work. Thanks also for his detailed review of this dissertation. I would also like to express my gratitude to my MS advisor Professor Nevin Selçuk of METU, Ankara, for introducing me to research and for her guidance—even with the distance and the passing of time. The friends and colleagues at the Mechanical Engineering Department including Professor Bora Süzen, Dr. Basil Wong, Dr. Hui Zhao, and Mathieu Francoeur have always been great support. The discussions with Dr. Ing. Regina Hannemann and Dr. Ing. Jens Hannemann of UK-Electrical Engineering Department and their willingness to share their deep understanding of the intricacies of electromagnetic theory, as well as their friendship is also greatly appreciated. My heartfelt gratitude is for the deep love that was always made apparent by my parents Nedret and Ibrahim Kozan, brother Melih, and sister Gül. For her loving nature, farsighted mind, her unwavering love, and for making everything worthwhile, Bilge—my wife, thank you. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS.......................................................................................iii TABLE OF CONTENTS........................................................................................... iv LIST OF TABLES.................................................................................................... vii LIST OF FIGURES .................................................................................................viii NOMENCLATURE ................................................................................................. xii CHAPTER 1 .......................................................................................................................1 PARTICLE CHARACTERIZATION AND NANOTECHNOLOGY — A HISTORICAL PERSPECTIVE 1.1. INTRODUCTION ............................................................................................... 1 1.1.1. Colloid Science and Nanotechnology........................................................... 2 1.1.2. Impact of Nanotechnology