FACTORS AFFECTING THE GROWTH AND FRAGMENTATION OF POLYFERROCENYLSILANE DIBLOCK COPOLYMER MICELLES By Jieshu Qian A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Chemistry University of Toronto © Copyright by Jieshu Qian, 2013 FACTORS AFFECTING THE GROWTH AND FRAGMENTATION OF POLYFERROCENYLSILANE DIBLOCK COPOLYMER MICELLES Jieshu Qian Doctor of Philosophy Graduate Department of Chemistry University of Toronto 2013 Abstract Polyferrocenylsilane (PFS) diblock copolymers self-assemble in selective solvents to form one-dimensional micelles for a broad range of polymer compositions and experimental conditions, driven by the crystallization of the PFS block that forms the micelle core. The most striking feature of these micelles is that they remain active for further growth. They can be extended in length when additional polymer, dissolved in a good solvent, is added to a solution of the pre-existing micelles. This thesis describes several studies investigating the factors that affect the growth and fragmentation of PFS diblock copolymer micelles in solution, with a particular emphasis on polyisoprene-PFS (PI-PFS) diblock copolymers. The goal of my research was trying to provide deeper understanding of this crystallization-driven self-assembly (CDSA) process. In an attempt to understand the growth kinetics of the PI-PFS cylindrical micelles, I added tiny amount of short micelle seeds into supersaturated solution of the same polymer, and followed the micelle growth by light scattering. The data analysis showed that the increase of micelle length could be described by an expression with two exponential decay terms. In another ii attempt to examine the factors that may affect the growth behavior of the PI-PFS micelles, I found that PI-PFS long micelles underwent fragmentation when they were subjected to external stimuli, e.g. addition of polar solvent, or heating. During the course of studying the effect of heating on the micelles, I developed a new approach to generate cylindrical micelles with controllable and uniform length, a one-dimensional analogue of self-seeding of crystalline polymers. I carried out a systematic study to investigate the self-seeding behavior of PFS block copolymers. iii Acknowledgements This thesis would not have been possible without the support, guidance, patience and encouragement of a great scientist, my supervisor Prof. Mitchell A. Winnik. I am truly indebted and thankful for that he teaches me how to be not only a better scientist but also a better person. The knowledge, skills, and experience I have acquired under his supervision will benefit me all through my career and life. I would like to express my gratitude and appreciation to Prof. Ian Manners from University of Bristol for his valuable suggestions, discussions and collaboration throughout my doctoral research. I also would like to thank Prof. Wenbing Hu from Nanjing University and Prof. Eugenia Kumacheva from University of Toronto for their fruitful suggestions. I owe sincere and earnest thankfulness to my colleagues and friends in the Winnik group. Particularly, I want to thank Dr. Yijie Lu for his enormous help on my research, Mr. Graeme Cambridge for providing polymer materials for my research, Dr. Gerald Guerin and Dr. Mohsen Soleimani for their helpful discussions, Ms. Anselina Chia for participating in part of my research. I am also much obliged to Mr. Meng Zhang, Dr. Chun Feng, Mrs. Wanjuan Lin, Mr. Guangyao Zhao, Mr. Peng Liu, Dr. Yi Hou, Dr. Lin Jia, Mr. Lemuel Tong, Dr. Nicolas Illy and all other members of the Winnik group for not only discussing science and also sharing happiness in life. In the end, I would like to express my gratitude to my beloved parents for their love and support during my whole life. This thesis is dedicated to them. I also would like to thank all my family members for their kind support, especially my cousin Xinyang Zhang for his help on data analysis. I am also deeply indebted to my dear wife Mrs. Min Feng for her long time support and making my life enjoyable. iv Table of Contents Abstract………………………………………………………………………………………… ii Acknowledgements……………………………………………...………..…….…………....... iv Table of Contents……………………………………………………………………………… v List of Tables…………………………………………………………………………………... x List of Schemes and Figures………………………………………………………………... xiii List of Appendices…………………………………………………………………………... xix Chapter 1. Introduction: Nanofiber Micelles from the Self-assembly of Block Copolymers in Solution………………………………………………………………………………… 1 1.1 Introduction: Self-assembly of Block Copolymers…………………………………………. 1 1.2 The Energy Landscape for Block Copolymer Self-assembly………………………………. 3 1.3 Theories of Nanofiber Micelle Formation by Block Copolymers………………………….. 4 1.4 Examples Classified by the Nature of the Block Copolymers……………………………… 5 1.4.1 Coil-coil Block Copolymers………………………………………………………………….. 7 1.4.2 Rod-coil Block Copolymers………………………………………………………………….. 12 1.4.3 Crystalline-coil Block Copolymers…………………………………………………………... 15 1.4.3.1 PFS Block Copolymers………………………………………………………………... 15 1.4.3.2 Non-PFS Block Copolymers………………………………………………………….. 23 1.4.4 Nanofibers from Disk-like Building Blocks and Other Examples…………………………… 29 1.5 Summary……………………………………………………………………………………. 32 1.6 Research Objectives and Thesis Outline……………………………………………………. 33 References………………………………………………………………………………………. 34 Chapter 2. Experimental: Material, Instrumentation, Method and Protocol……………... 40 2.1 Material……………………………………………………………………………………... 40 2.1.1 Solvents……………………………………………………………………………………….. 40 2.1.2 Polymers……………………………………………………………………………………… 40 v 2.2. Instrumentation…………………………………………………………………………….. 42 2.2.1 Transmission Electron Microscopy (TEM)…………………………………………………... 42 2.2.2 Light Scattering……………………………………………………………………………….. 42 2.2.3 Gel Permeation Chromatography (GPC)……………………………………………………... 43 2.2.4 Atomic Force Microscopy (AFM)……………………………………………………………. 43 2.2.5 Nuclear Magnetic Resonance (NMR)………………………………………………………… 43 2.2.6 Heating Bath and Temperature Control………………………………………………………. 44 2.2.7 Sonication…………………………………………………………………………………….. 44 2.3 Image Analysis Method…………………………………………………………………….. 44 2.3.1 Image Analysis……………………………………………………………………………….. 44 2.3.2 PDI……………………………………………………………………………………………. 46 2.3.2.1 Example 1...…………………………………………………………………………… 46 2.3.2.2 Example 2……………………………………………………………………………... 47 2.3.2.3 Example 3……………………………………………………………………………... 47 2.3.2.4 Example 4……………………………………………………………………………... 48 2.3.2.5 Example 5……………………………………………………………………………... 49 2.3.2.6 Example 6……………………………………………………………………………... 49 2.4 Experimental Protocol: Seeded Growth…………………………………………………….. 50 References………………………………………………………………………………………. 54 Chapter 3. Solvent-induced Fragmentation of Fiber-like PI1000-PFS50 Block Copolymer Micelles……………………………………………………………………………………. 55 3.1 Introduction…………………………………………………………………………………. 55 3.2 Experimental………………………………………………………………………………... 59 3.2.1 Seeded Growth of PI-PFS Block Copolymer Micelles………………………………………. 59 3.2.2 Adding THF into Micelle in Decane Solutions………………………………………………. 60 3.2.3 Adding Decane into Polymer in THF Solutions……………………………………………… 60 3.2.4 Test of the Supersaturation for Micellization………………………………………………… 60 3.3 Results and Discussion……………………………………………………………………… 61 3.3.1 Seeded Growth of PI-PFS Block Copolymer Micelles………………………………………. 61 3.3.2 Effect of Adding THF into Micelle in Decane Solutions…………………………………….. 64 3.3.3 Kinetics of CLD Evolution Induced by the Addition of THF………………………………... 68 vi 3.3.4 Effect of Adding Decane into Polymer in THF Solutions……………………………………. 70 3.3.5 Test of Supersaturation Region for Micellization…………………………………………….. 73 3.4 Conclusion………………………………………………………………………………….. 75 References………………………………………………………………………………………. 76 Chapter 4. Growth Kinetics of Fiber-like PI1000-PFS50 Block Copolymer Micelles……….. 77 4.1. Introduction………………………………………………………………………………… 77 4.2 Experimental………………………………………………………………………………... 82 4.2.1 Preparation of Micelle Seed Solution………………………………………………………… 82 4.2.2 Preparation of Micelle Solutions for the Correlation of Scattering Intensity with Micelle Length…………………………………………………………………………………………. 82 4.2.3 Study of Micelle Growth Kinetics……………………………………………………………. 83 4.2.4 Diffusion Coefficient of PI800-PFS20 Polymer Chains in decane/THF Mixture……………… 85 4.3 Results and Discussion……………………………………………………………………… 85 4.3.1 Static Light Scattering Theory………………………………………………………………... 87 4.3.2 A Simple Growth Model……………………………………………………………………… 89 4.3.3 Correlation of Scattering Intensity with Micelle Length……………………………………... 91 4.3.4 Kinetics Data of Trial V10T11M05…………………………………………………………... 95 4.3.5 Fitting of the Kinetics Data of Trial V10T11M05……………………………………………. 99 4.3.6 Additional Kinetics Experiments…………………………………………………………..... 101 4.3.7 Kinetics Models Leading to Double Exponential Decay Kinetics…………………………... 109 4.3.8 A Model for Diffusion Controlled Micelle Growth…………………………………………. 114 4.3.9 Experiments at Higher Unimer Concentrations……………………………………………... 118 4.4 Conclusion…………………………………………………………………………………. 125 References……………………………………………………………………………………… 127 Appendix I to Chapter 4……………………………………………………………………...… 129 Appendix II to Chapter 4………………………………………………………………………. 139 AII-4.1 Dynamic Light Scattering Theory………………………………………………………… 139 AII-4.2 Experimental Correlation between Rh,app and length L……………………………………. 142 AII-4.3 Evolution of Rh,app Over Time for Kinetics Experiments…………………………………. 144 AII-4.4 Analysis of Evolution of Rh,app