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Performing Ring Opening Metathesis Polymerization (Romp) PERFORMING RING OPENING METATHESIS POLYMERIZATION (ROMP) REACTIONS AND POST-POLYMERIZATION MODIFICATIONS UNDER FLOW CONDITIONS ___________ A Thesis Presented to The Faculty of the Department of Chemistry Sam Houston State University ___________ In Partial Fulfillment of the Requirements for the Degree of Master of Science ___________ by Selesha I. Subnaik May, 2020 PERFORMING RING OPENING METATHESIS POLYMERIZATION (ROMP) REACTIONS AND POST-POLYMERIZATION MODIFICATIONS UNDER FLOW CONDITIONS by Selesha I. Subnaik ___________ APPROVED: Christopher E. Hobbs, PhD Committee Director Dustin E. Gross, PhD Committee Member Christopher M. Zall, PhD Committee Member John Pascarella, PhD Dean, College of Science and Engineering Technology DEDICATION To my family and friends for the unconditional love and support. iii ABSTRACT Subnaik, Selesha I., Performing Ring Opening Metathesis Polymerization (ROMP) Reactions and Post-Polymerization Modifications Under Flow Conditions. Master of Science (Chemistry), May, 2020, Sam Houston State University, Huntsville, Texas. Ring opening metathesis polymerization (ROMP) reactions of norbornene derived monomers and Grubbs 3rd Generation catalyst were run under continuous flow conditions. Typically, ROMP reactions are performed using “batch” reaction conditions that involve the use of round-bottomed flasks and mechanical stirrers to allow for mixing. Further, these experiments are typically carried out under inert atmospheres to achieve oxygen exclusion and prevent catalyst death, which can affect the expected monomer to initiator ([M]:[I]) ratio of the polymerization reaction. However, under continuous flow conditions, the ROMP reactions in this study were performed under air atmosphere using a simple bench-top setup with syringe pumps, segments of reaction tubing, connectors and syringes that allowed for betting mixing, and excessive reaction times which can lead to less controlled polymerization reactions. Nuclear magnetic resonance (NMR) analysis provided percent conversion of monomer to polymer, and gel permeation chromatography (GPC) analysis provided number-average molecular weights (Mn) and polydispersity index (PDI, Đ) values. Homopolymerization reactions were performed with residence times (tR) of 22.5 s and 7.5 s. Đ values ranged from 1.14-1.33 and 1.07- 1.18 for tR =22.5 s and tR=7.5s, respectively, for most norbornene derived monomers studied. Monocyclic monomers such as cyclopentene, cyclooctene and cyclooctadiene were not able to be successfully analyzed post polymerization under flow conditions to give an indication of control over the reactions. Block copolymers consisting of a block of norbornene followed by a block of exo-functionalized norbornene were synthesized iv using a tR of 22.5 s. Percent conversions were >95% for all block copolymerization reactions. Thio-bromo click reactions were performed in flow where an exo-α-bromo ester functionalized norbornene monomer was polymerized in flow and subsequently followed in-line with a solution of thiol and triethylamine for a “click” reaction to occur. Both the polymerization and the thio-bromo click reaction percent conversions were >95% as determined by 1H NMR. KEY WORDS: Continuous flow, Ring opening metathesis polymerization (ROMP), Norbornene, Homopolymerization, Block copolymerization, Thio-bromo “click” reaction, Post-polymerization modification v ACKNOWLEDGEMENTS Thank you to my research advisor Dr. Christopher Hobbs for his guidance and support. During my two years here at Sam Houston State University (SHSU) I have had the privilege of improving my understanding of both organic chemistry and polymer science under his tutelage. His dedication to his research and his students in the lab and classroom has helped to make me a more confident and better chemist. Thank you to both Dr. Dustin Gross and Dr. Christopher Zall for serving on my committee. Their corrections towards my thesis and support for my defense is much appreciated. Thank you to Dr. Arney for the company, great conversation and help (especially during the weekends I’ve spent doing research in the chemistry building). Thank you to the faculty and staff of the SHSU Chemistry department who have supported and facilitated the daunting task of pursuing a master’s degree less unnerving with their kind words of support and smiling faces. To my friends, thank you for welcoming me into your friend groups, you all made the sting of living far from family hurt less. I share with you my favorite quote from Maya Angelou: “I’ve learned that people will forget what you said, people will forget what you did, but people will never forget how you made them feel”—and it’s true, I will always remember and appreciate you all being a part of this journey. Lastly, thank you to my family. Mommy and Daddy, a simple thank you is not enough to express how grateful I am for your unwavering love and support no matter what I choose to do. Thank you for giving me this beautiful life. vi TABLE OF CONTENTS Page DEDICATION ................................................................................................................... iii ABSTRACT ....................................................................................................................... iv ACKNOWLEDGEMENTS ............................................................................................... vi TABLE OF CONTENTS .................................................................................................. vii LIST OF TABLES ............................................................................................................. ix LIST OF FIGURES ............................................................................................................ x CHAPTER I: INTRODUCTION ................................................................................... 1 1.1 Living polymerization.......................................................................................... 1 1.2 Continuous flow polymerization ......................................................................... 2 1.3 Olefin metathesis ................................................................................................. 4 1.4 Polymer characterization terminology (Mn, Mw, Đ) .......................................... 10 1.5 “Click” reactions ................................................................................................ 12 1.6 Aim of this research ........................................................................................... 15 CHAPTER II: MATERIALS AND METHODS ........................................................... 16 2.1 General ............................................................................................................... 16 2.2 Synthesis ............................................................................................................ 17 2.3 General procedure for continuous flow homopolymerizations ......................... 25 2.4 General procedure for continuous flow copolymerizations ............................... 27 2.5 General procedure for continuous flow ROMP & thio-bromo “click” reactions ................................................................................................................... 29 2.6 1H NMR percent conversion determination....................................................... 31 vii 2.7 Precipitation methodology ................................................................................. 33 CHAPTER III: RESULTS AND DISCUSSION ............................................................ 34 3.1 Optimizing reaction conditions .......................................................................... 34 3.2 endo/exo selectivity............................................................................................ 36 3.3 Flow ROMP homopolymerization study ........................................................... 38 3.4 Homopolymerizations at shorter residence time ............................................... 39 3.5 Monomer scope.................................................................................................. 42 3.6 ROMP in flow “livingness” study ..................................................................... 45 3.7 Block copolymerizations ................................................................................... 47 3.8 Thio-bromo “click” reactions ............................................................................ 49 CHAPTER IV: CONCLUSION ...................................................................................... 52 REFERENCE .................................................................................................................... 54 APPENDIX ....................................................................................................................... 61 VITA ................................................................................................................................. 80 viii LIST OF TABLES Table Page 1 Polymer size classification based on Đ values. ...................................................... 11 2 Homopolymerizations under flow conditions ......................................................... 35 3 Endo/exo 5 at varying residence times ................................................................... 38 4 Homopolymerizations under flow conditions with tR = 22.5 s. .............................. 38 5 Flow homopolymerization of norbornene derived monomers performed at 0 °C. 39 6 Homopolymerizations under
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