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Swager for the Degree of California Institute PRECURSOR ROUTES TO CONDUCTING POLYMERS FROM THE RING-OPENING METATHESIS POLYMERIZATION OF CYCLIC OLEFINS Thesis by Timothy Manning Swager In Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 1988 (Submitted May 16, 1988) I a ELECTRONS TALK TO ME! Oh elusive electron how can I set thee free? I’ll unlock your chains just show me the key. Should I destroy your captors those localized bonds? Or would you like something else should I search beyond? I want to let you run and move about with ease. And you may travel in pairs or alone if you please. Lead me the way to that magic superconductive state. And I will do my best to try to accommodate. I’ll build you a band of whatever width you desire. And with my friend polymer chemistry I’ll fashion you a wire. You hold the secrets that can make the world a better place. And I have become curious and decided to join the chase. Oh magnificent electrons hear my plea I have come to set you free. Timothy M. Swager 1988 11 ACKNOWLEDGMENTS First and foremost, I want to thank my wife and best friend Anne for her undaunting support and companionship. I cannot imagine life without her and her influence has made me a happier and stronger person. To my research advisor Bob Grubbs, I owe considerable gratitude and thanks. His guidance will have lasting influence over my career as a chemist. Bob has allowed me to chase many pipe dreams in his laboratory, yet given me the necessary guidance to keep my research on course. I appreciate the fact that he has tolerated all my crazy ideas and allowed me to discover things for myself. It has been a pleasure working in his group. I thank Dennis Dougherty for his interest in my work and his patience as chairman of my committee. To my parents I owe the most thanks of all. They raised me with the mind-set that I can be successful and that education is indeed a virtue. Their support for my career has been the basis of much of my motivation and for that I will be forever grateful. There are many other people that I feel gratitude toward for my experience at Caltech. Working in an atmosphere of people who love to talk science and are so willing to think about each other’s projects has made a major contribution to my scientific background. Ill ABSTRACT Chapter 1 provides an introduction to the field of conductive polymers. The perspective is that of a chemist who is also interested in the physics of conductive polymers. The concepts discussed in this chapter are referred to throughout the other chapters, and should be a good primer for newcomers to this field as well as a reference to the literature for others. This chapter sets the stage for the theme of this thesis, which is the use of soluble precursor polymers in the synthesis of conductive polymers. Recent work was cited in this chapter which is not available in existing reviews of conductive polymers. The method of ring-opening metathesis polymerization (ROMP) is discussed in Chapter 2. The concepts discussed therein are again referred to throughout the following chapters. The ideas of catalyst matching for different monomers are dis­ cussed, and particular emphasis is given to the steric requirements of the catalysts. The ROMP of derivatives of dimethylene cyclobutene is discussed in Chapter 3. However, the primary focus of the chapter is on the polymer polydiisopropyli- denecyclobutene. This material is distinctly different from other conductive poly­ mers in the fact that it has a structure consisting of triene units that are mutually orthogonal to each other. A detailed study of this material with a variety of spec­ troscopies and measurements is presented. The synthesis of polybenzvalene, and the isomerization of this material to poly­ acetylene, is discussed in Chapter 4. This work constitutes a new precursor method to this fundamentally important polymer, as well as a demonstration of the far reaching scope of ROMP. Polybenzvalene is also a high energy material and has unusual explosive properties which are also discussed. In Chapter 5, new precursor routes to conductive polymers based on the elimi­ nation and hydrolysis of ketals are presented. This work has been primarily focused iv on structural chemistry and how to best transform the precursor polymers into con­ ductive polymers. The majority of the effort has been focused on the poly(quinone bisketals); however, another example of this concept is presented briefly. V TABLE OF CONTENTS page ACKNOWLEDGMENTS..............................................................................................................fi ABSTRACT............. ........................................................................................................... iii LIST OF TABLES............................................................................................................................. ⅛ LIST OF FIGURES, SCHEMES AND EQUATIONS.........................................x CHAPTER 1. AN INTRODUCTION TO CONDUCTIVE POLYMERS: A CHEMICAL PERSPECTIVE........................................................................................................1 Introduction.........................................................................................................................................2 History....................................................................................................................................................4 Electronic Structures......................................................................................................................5 Carriers and Doped Materials.................................................... 9 The Metallic State.........................................................................................................................14 Synthesis and Processing...........................................................................................................17 Conductivity; Concepts and Measurement............................................... 25 Future Outlook...................................................................................... 30 References........... ...............................................................................................................................31 CHAPTER 2. RING OPENING METATHESIS POLYMERIZATION............. 36 Introduction to Olefin Metathesis.........................................................................................37 Ring Opening Metathesis Polymerization: “ROMP”...............................................40 Nature of the Catalysts......................................................................... 41 References...........................................................................................................................................49 VI CHAPTER 3. POLYMERS FROM THE RING OPENING METATHESIS POLYMERIZATION OF DIMETHYLENECYCLOBUTENE AND ITS DERIVATIVES .......... 51 Polymerization of Dimethylenecyclobutene.....................................................................52 Introduction.......................... 52 Results and Discussion...............................................................................................................54 Polymerization of DMCB.......................................................................................... 54 Doping and Conductivity of Polymers..................................................................... 63 Thermogravimetric Analysis...........................................................................................63 Conclusions............................................................................................................... 65 The Synthesis and Properties of Poly(3,4-Diisopropylidenecyclobutene) ... 68 Introduction................................................................................................................ 68 Results and Discussion...............................................................................................................70 Polymerization of DICB.............................................................................................. 70 Block Copolymers......................................................................................... 75 Thermal Properties.............................................................................................................78 Conformational Properties of PDICB.................................................................. 79 Morphology and Processing of PDICB................................................................ 82 Doping and Conductivity of PDICB.................................................................... 84 Characterization of Doped PDICB....................................................................... 87 Infrared Characterization of Doped PDICB......................................................90 Electron Spin Resonance Studies of PDICB.................................................... 92 Vil Magnetic Susceptibility of Doped PDICB............................................... 97 Solid State 13 C NMR of Doped PDICB....................................... 102 Compensation of Doped PDICB.............................. 106 Conclusions....................................................................................................................................108 Future Outlook of the Polymerization of Derivatives of Dimethylenecyclobutene..........................................................................................................109
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