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Synthesis of DMAP Tethered Polymer Chains for Reversible Micelle Formation Richard Arthur Fredricks

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Synthesis of DMAP Tethered Polymer Chains for Reversible Micelle Formation Richard Arthur Fredricks Eastern Michigan University DigitalCommons@EMU Master's Theses, and Doctoral Dissertations, and Master's Theses and Doctoral Dissertations Graduate Capstone Projects 2016 Synthesis of DMAP tethered polymer chains for reversible micelle formation Richard Arthur Fredricks Follow this and additional works at: http://commons.emich.edu/theses Part of the Chemistry Commons Recommended Citation Fredricks, Richard Arthur, "Synthesis of DMAP tethered polymer chains for reversible micelle formation" (2016). Master's Theses and Doctoral Dissertations. 770. http://commons.emich.edu/theses/770 This Open Access Thesis is brought to you for free and open access by the Master's Theses, and Doctoral Dissertations, and Graduate Capstone Projects at DigitalCommons@EMU. It has been accepted for inclusion in Master's Theses and Doctoral Dissertations by an authorized administrator of DigitalCommons@EMU. For more information, please contact [email protected]. Synthesis of DMAP Tethered Polymer Chains for Reversible Micelle Formation by Richard Arthur Fredricks Thesis Submitted to the Department of Chemistry Eastern Michigan University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in Chemistry Thesis Committee: Gregg Wilmes, PhD, Chair Harriet Lindsay, PhD Donald Snyder, PhD December, 2016 Ypsilanti, MI Acknowledgments I would like to thank Dr. Gregg Wilmes. I really appreciate his support with my research and for accommodating my work schedule. I would also like to thank all of the faculty at EMU for everything that I have learned during my time in the chemistry program. I would also like to thank my family and friends for all of the support while I have been earning my degree. ii Abstract Dimethylaminopyridine (DMAP) can act to catalyze numerous organic reactions. To increase its recovery and reuse, it has been tethered to dendrimers and to micellar systems, creating nano-scale catalytic pockets for reactions to proceed. Previously developed systems show diminished reactivity over time as the products of the reaction fill up the nano-scale reactor. Thus, the goal of my research is to use RAFT polymerization methods to synthesize a hydrophobic polymer chain bearing 4-methylaminopyridine units and to attach it to a hydrophilic polymer chain to create a polymer system capable of micelle formation in solution. These functionalized micelles are designed to be selectively opened and closed by changing the temperature, thus allowing the product to be removed from the micelle and avoiding the diminished catalytic activity that other polymer-supported catalytic systems show. A monomer with DMAP-like activity was made by reacting 4-methylaminopyridine with 3-isopropenyl-α,α- dimethylbenzyl isocyanate that could be polymerized into a hydrophobic polymer chain, and progress towards polymerizing the functionalized monomer was made. iii Table of Contents Acknowledgments..................................................................................................................ii Abstract ..................................................................................................................................iii List of Reaction Schemes.......................................................................................................vi List of Figures ........................................................................................................................vii Chapter 1: Introduction ..........................................................................................................1 1.1– Dimethylaminopyridine (DMAP) as a catalyst..................................................1 1.2 – Polymer-tethered DMAP .................................................................................3 1.3 – Polymerization Overview .................................................................................8 1.4– Polymer Synthesis ..............................................................................................9 1.5– Molecular Weight Distributions ........................................................................12 1.6– Block Copolymers and Applications .................................................................13 1.7– Controlled Free Radical Polymerization ............................................................14 1.8– Summary and Current Challenges .....................................................................17 Chapter 2: Research Summary ...............................................................................................18 2.1 – Research Focus .................................................................................................18 2.2 – Results and Discussion .....................................................................................18 Chapter 3: Conclusions and Future Work ..............................................................................25 iv Chapter 4: Experimental ........................................................................................................26 4.1 – Materials ...........................................................................................................26 4.2 – Reaction Scheme 2 ............................................................................................26 4.3 – Reaction Scheme 3 ............................................................................................26 4.4 – Reaction Scheme 4 ............................................................................................27 4.5 – Reaction Scheme 5 ............................................................................................27 4.6 – Reaction Scheme 6 ............................................................................................28 4.7 – Reaction Scheme 7 ............................................................................................28 4.8 – Reaction Scheme 8 ............................................................................................29 References ..............................................................................................................................30 v List of Reaction Schemes Reaction Scheme 1 – Proposed two-step reaction to create a free radical polymerizable monomer with DMAP functionality ....................................................19 Reaction Scheme 2 – Reaction of 2-chloroethanol with 4-methylaminopyridine .................20 Reaction Scheme 3 – Reaction of 2-chloroethanol with 4-methylaminopyridine with sodium hydride ....................................................................................20 Reaction Scheme 4 – Reaction of 2-chloroethanol with 4-methylaminopyridine with sodium hydride conducted via microwave heating ............................21 Reaction Scheme 5 – Two-step reaction process to produce protected alcohol with DMAP functionality ............................................................................21 Reaction Scheme 6 – Proposed reaction product of reacting acrylic acid with 2-chloroethanol with a carbodiimide catalyst .....................................22 Reaction Scheme 7 – Synthetic route for preparation of a polymerizable monomer with DMAP-like functionality .....................................................................23 Reaction Scheme 8 – Attempted polymerization of DMAP functionalized monomer with methyl methacrylate without solvent ..........................................24 vi List of Figures Figure 1 – Reactions catalyzed by DMAP .............................................................................1 Figure 2 – Mechanism of acylation catalyzed by DMAP ......................................................2 Figure 3 – Reaction scheme for the creation of a polyurethane shell around a DMAP containing polymer ...............................................................................................4 Figure 4 – Polyurethane shell polymerized around DMAP containing catalyst ....................5 Figure 5 – A dendrimer containing DMAP in the interior region .........................................6 Figure 6 – Three dimensional representation of a micelle .....................................................7 Figure 7 – Types of copolymer architectures ........................................................................9 Figure 8 – Free radical polymerization .................................................................................11 Figure 9 – Formulas for the determination of the molecular weight distributions, Mn and Mw ......................................................................................12 Figure 10 – Comparison of RAFT polymerization versus traditional radical polymerization .......................................................................................14 Figure 11 – Mechanism of RAFT polymerization .................................................................16 Figure 12 – 1H NMR spectra of product of reaction of m-TMI and 4-methylaminopyridine ......................................................................................23 vii Chapter 1: Introduction 1.1. Dimethylaminopyridine (DMAP) as a Catalyst Dimethylaminopyridine is a very useful catalyst. It catalyzes a large variety of organic reactions such as acylation, the Baylis-Hillman reaction, the Steiglich Rearrangement, and the Staudinger rearrangement of β-lactams, as shown in Figure 1.1 Acylation, shown below in Figure 2, is one of the more commonly DMAP catalyzed reactions. DMAP is a readily available catalyst and is very inexpensive.
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