Functionalized Polymers and Surfaces Via Ring-Opening Metathesis Polymerization
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Functionalized Polymers and Surfaces via Ring-Opening Metathesis Polymerization Thesis by Isaac Michael Rutenberg In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy California Institute of Technology Pasadena, California 2005 (Submitted August 13th, 2004) ii c 2005 Isaac Michael Rutenberg All Rights Reserved iii Acknowledgements I would like to thank the following people, all of whom have played important roles in my journey through Caltech. Professor Robert H. Grubbs (i.e., ”Bob”) has provided the opportunity and the support (moral and financial!) that have allowed me to pursue my own path in becoming a competent research chemist. I am also grateful to Bob for showing me that serious chemistry need not always be taken so, well, seriously. In addition to Bob, I thank the remaining members of my Committee - Prof. William A. Goddard III (Chairman), Prof. Dennis Dougherty, and Prof. James Heath. Dr. (now Professor) Zhenan Bao and Professor Chad Mirkin have been extremely supportive, and have allowed me to gain experience in a variety of fields that may not have otherwise been accessible. Good luck to Prof. Bao with her new position on the faculty of Stanford. For their invaluable friendship and generosity over the past four years, I would especially like to thank Oren A. Scherman and his wife, Cora Iberkleid. Collaborating students have been particularly kind and helpful; many thanks to Tae-Lim Choi and Weirong Jiang. Xiaogang ”Bruno” Liu has been very helpful in seeing that the collaboration with the Mirkin group at Northwestern University runs smoothly. I am grateful to have him as a colleague and for his continued updates on the SI-ROMP project! The following people have been instrumental in helping me to learn ”tools of the trade”: Dr. Hyunjin Kim, Dr. Andreas Killbinger, Dr. Steve Goldberg, Dan Sanders, Dr. Stu Cantrill, Dr. Choon Woo Lee, Dr. Todd Younkin, Dr. J.P Morgan, Dr. Brian Connell, Mona Shahgholi, and Tom Dunn. iv I thank many people for their thoughtful and insightful comments, and for proofreading my papers, proposals, and thesis. These people include Dr. Brian Connell, Andy Hejl, Dan Sanders, Dr. Anna Wenzel, and Dr. Anatoly Chlenov. There are many other people with whom I’ve interacted over the past four years, and I would be remiss if I did not pay my respects to the Grubbs group at large. Thank you all for helping, being patient, and teaching me. I could not have asked for a more friendly environment in which to work, and this is in large part due to the students and postdocs. Logistical support provided by Dian Buchness, Anne Penney, Joe Drew, Steve Gould, and Larry Martinez is appreciated. On a personal note, I would like to thank Bill and Delores Bing (Band and Chamber music directors, respectively), and Robert Dirks (for teaching me bridge, keeping me ”well-rounded” with numerous game nights, and simply being a great friend). Special thanks to the Diener family for welcoming me into their lives without reservation. Having a surrogate family here has allowed California to become comfortable, as a home should be. Donna, Jim, Josh, Joe and the extended family have been simply amazing, and I would not have wanted to live here without them. Thank you, and may the future be bright for each of you! My sincere appreciation also goes to the Kamau family for welcoming me as a son. My brother and sister, Ben and Naomi Rutenberg, and my soon-to-be sister- in-law, Nguyen Vu, each deserve many thanks for helping me to remember that I have a place, not too far from here, where I can always go and fit in just like a member of the family (because that’s what I am!). Most importantly, and in no particular order, I thank Wanjiru, whom I will marry on August 21st, my mother, who has become my best friend, my father, who has shaped me in so many ways, and Murray, who is all of the above in one amazing package. These individuals I thank for their unconditional love, support, and tolerance. Emphasis on the ”tolerance” part. Thanks, everyone! v Abstract The research presented in this thesis focuses on the preparation of functional- ized polymers using olefin metathesis polymerization methods. A portion of this research is also devoted to the development of applications for metathesis-derived polymers. Three distinct types of olefin metathesis polymerizations can be recognized within this work. Ring-opening metathesis polymerization (ROMP) is the most prevalent type, followed by acyclic diene metathesis (ADMET) polymerization and a hybrid of the ROMP and ADMET mechanisms known as ring-opening- insertion metathesis polymerization (ROIMP). Many of the concepts that appear throughout this thesis are introduced in Chapter 1. Olefin metathesis occupies a central role in each of the subsequent chapters; detailed descriptions of the mechanism and important olefin metathesis catalysts are provided. The chapter also includes background information regard- ing polymers, polymer properties and the application of ROMP in the construction of electronic devices. Although the utility of ADMET does not yet seem to match that of ROMP, valuable information can be obtained from ADMET polymerizations. In an effort to elucidate catalytic activity, Chapter 2 details a comparison of the ADMET polymerizations of terminal and non-terminal dienes. Experimental investigations involving ROIMP, a novel method for the produc- tion of A,B-alternating copolymers, is presented in Appendix A. The mechanism of ROIMP is conceptually very different from the mechanisms of either step growth vi or chain growth polymerizations. Efforts toward understanding the mechanism of ROIMP using a mathematical model are discussed in Chapter 3. Polymeric chain transfer agents (PCTAs) suitable for ROMP reactions are poly- mers that contain a single, metathesis-active olefin. These polymers are the focus of Chapter 4 and can be used in the preparation of novel block copolymers. As an example, Appendix B presents the preparation of block copolymers consisting of polyacetylene and various commodity polymers. Finally, the development of applications for surface-initiated ROMP (SI-ROMP) is discussed in Chapter 5 and Appendix C. Polymer films prepared using SI- ROMP are shown to be viable dielectric layers in thin-film transistors, and research is presented involving microcontact printing and dip pen nanolithography as methods for forming patterned SI-ROMP polymer films. vii Contents Acknowledgements iii Abstract v 1 Introduction 1 1.1 PolymersandPolymerProperties. 2 1.2 OlefinMetathesis .............................. 3 1.3 Polymerizations............................... 5 1.4 Electronicdevices.............................. 8 ReferencesCited.................................. 10 2 Acyclic Diene Metathesis (ADMET) Polymerization Using a Ruthenium Olefin Metathesis Catalyst Coordinated with a N-Heterocyclic Carbene Ligand 12 2.1 Abstract ................................... 13 2.2 Introduction ................................. 13 2.3 Experimental ................................ 15 2.4 ResultsandDiscussion .. .. .. .. .. .. .. .. 16 2.5 Conclusion.................................. 19 ReferencesCited.................................. 20 3 Understanding Ring-Opening-Insertion Metathesis Polymerization: Math- ematical Models of Insertion Polymerizations 21 3.1 Abstract ................................... 22 viii 3.2 Introduction ................................. 22 3.3 ResultsandDiscussion .. .. .. .. .. .. .. .. 25 3.4 Conclusions ................................. 31 ReferencesCited.................................. 32 4 Development of Polymeric Chain Transfer Agents for Use in Ring- Opening Metathesis Polymerizations 33 4.1 Abstract ................................... 34 4.2 Introduction ................................. 34 4.3 ResultsandDiscussion .. .. .. .. .. .. .. .. 37 4.3.1 SynthesisofAsymmetricPCTAs . 37 4.3.2 SynthesisofSymmetricPCTAs . 37 4.3.2.1 CouplingofPre-formedPolymers . 38 4.3.2.2 GeneratingSymmetricPCTAsinsitu . 40 4.3.3 TheUseofPCTAsinROMP. 46 4.4 Conclusions ................................. 50 4.5 Experimental ................................ 51 ReferencesCited.................................. 53 5 Patterned Polymer Layers Using Surface-Initiated Ring-Opening Me- tathesis Polymerization 55 5.1 Abstract ................................... 56 5.2 Introduction ................................. 56 5.3 ResultsandDiscussion .. .. .. .. .. .. .. .. 59 5.3.1 ElectronicDevicesUsingSI-ROMP. 59 5.3.2 PatterningofSI-ROMPLayers . 66 5.4 Conclusions ................................. 71 5.5 ExperimentalSection ............................ 71 ReferencesCited.................................. 75 Appendices 76 ix A Synthesis of A,B-Alternating Copolymers by Ring-Opening-Insertion Metathesis Polymerization 76 A.1 Abstract ................................... 77 A.2 Introduction ................................. 77 A.3 ResultsandDiscussion . 79 A.4 Conclusion.................................. 83 A.5 Experimental ................................ 83 ReferencesCited.................................. 86 B Direct Synthesis of Soluble, End-Functionalized Polyenes and Poly- acetylene Block Copolymers 87 B.1 Abstract ................................... 88 B.2 Introduction ................................. 88 B.3 ResultsandDiscussion .. .. .. .. .. .. .. .. 91 B.3.1 SynthesisofSolublePolyenes . 91 B.3.1.1 CharacterizationofSolublePolyenes . 94 B.3.2 Synthesis ofPA-containingBlockCopolymers . .. 98 B.3.2.1 CharacterizationofBlockCopolymers . 101 B.4 Conclusions .................................106