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Controlled Free-Radical Polymerization at High Pressures: Synthesis And University of Massachusetts Amherst ScholarWorks@UMass Amherst Doctoral Dissertations 1896 - February 2014 1-1-2004 Controlled free-radical polymerization at high pressures : synthesis and properties of poly(α-substituted acrylates). Javid, Rzayev University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/dissertations_1 Recommended Citation Rzayev, Javid,, "Controlled free-radical polymerization at high pressures : synthesis and properties of poly(α-substituted acrylates)." (2004). Doctoral Dissertations 1896 - February 2014. 1055. https://scholarworks.umass.edu/dissertations_1/1055 This Open Access Dissertation is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Doctoral Dissertations 1896 - February 2014 by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. CONTROLLED FREE-RADICAL POLYMERIZATION AT HIGH PRESSURES: SYNTHESIS AND PROPERTIES OF POLY(a-SUBSTITUTED ACRYLATES) A Dissertation Presented by JAVID RZAYEV Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY February 2004 Polymer Science and Engineering © Copyright by Javid Rzayev 2004 All Rights Reserved CONTROLLED FREE-RADICAL POLYMERIZATION AT HIGH PRESSURES: SYNTHESIS AND PROPERTIES OF POLY(a-SUBSTITUTED ACRYLATES) A Dissertation Presented by JAVID RZAYEV Approved as to style and content by: Jacques Penelle, Chair Todd Emrick, Member Vincent Rotello, Member Shaw Ling Hsu, Def^rtment Head Polymer Science and Engineering DEDICATION To my parents Zakir and Zenfira. ABSTRACT CONTROLLED FREE-RADICAL POLYMERIZATION AT HIGH PRESSURES: SYNTHESIS AND PROPERTIES OF POLY(a-SUBSTITUTED ACRYLATES) FEBRUARY 2004 JAVID RZAYEV, B.S., MIDDLE EAST TECHNICAL UNIVERSITY M.S., UNIVERSITY OF MASSACHUSETTS AMHERST Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Jacques Penelle The free-radical polymerization of a series of a-substituted acrylic acid derivatives has been achieved by using hydrostatic pressure as a kinetic and thermodynamic driving force. It is shown that conducting polymerization in a range of pressures between 1 and 9 kbar dramatically improves the polymerizabilities of the investigated acrylates, opening the way to the synthesis of high-molecular weight polymers in short reaction times. The polymerizabilities of a-alkylacrylates at ambient pressure, obtained by extrapolation from high-pressure kinetic data, correlate well with Meyer's steric parameters for the relevant a-alkyl group. While the polymerization of a-alkylacrylates with linear alkyl groups proceeded via a vinyl double-bond addition in a traditional way, methyl a- isobutylacrylate polymerized though alternating steps of addition and 1,5-hydrogen transfer from the penultimate unit to provide an isomeric a-branched polymer structure. have Structure-property relationships for the synthesized poly(a-substituted acrylates) thermodynamic been investigated. Increasing the size of the a-alkyl group decreases thermal and photo-degradation. stability of the poly(a-alkylacrylates), and facilitates their vi Conformational transitions of poly(a-alkylacrylic acid)s in aqueous solutions are shown to be highly dependent on the size of the a-alkyl group. The transition pH can be fine- tuned by adjusting the total hydrophobic content of the polymer via copolymerization of a-alkylacrylic acid with different alkyl substituents. A high-pressure reversible addition- fragmentation chain transfer (HP-RAFT) protocol for controlled/living free-radical polymerization has been developed. It is demonstrated that this HP-RAFT technique can be used to livingly polymerize sterically hindered monomers, such as methyl ethacrylate, to provide polymers with low polydispersities, controlled molecular weights and end-groups. A methodology for the synthesis of well- defined poly(ethacrylic acid) has been developed. The controlled polymerization of polystyrene-methacrylate macromonomers has been achieved by HP-RAFT, providing densely branched comb-like polymers with controlled molecular weight characteristics. The synthesis of linear-comb diblock copolymers is also achievable by this technique. The HP-RAFT polymerization of traditional monomers, such as methyl methacrylate (MMA), has been investigated. It is demonstrated that the methodology allows for the synthesis of ultra-high molecular weight polymers with low polydispersities. The technique was used to obtain well-defined PMMAs with molecular weights of more than one million. vii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS v ABSTRACT vi LIST OF TABLES xiii LIST OF FIGURES xiv LIST OF SCHEMES xvii CHAPTER 1. INTRODUCTION 1 Background 1 Goal and Motivations 3 Experimental Strategy 4 a-Substituted Acrylates 7 Dissertation Plan 9 References 10 2. POLYMERIZATION OF STERICALLY CONGESTED a-ALKYLACRYLATES UNDER HIGH PRESSURE 13 Introduction 13 Experimental Section 14 Materials 14 Synthesis of Dimethyl Alkylmalonates 14 Synthesis of Methyl a- Alkylacrylates 15 Polymerizations at High Pressure 16 Measurements 1^ Results and Discussion 1^ High Pressure Polymerizations 1^ Quantitative Correlation of Steric Effects to Polymerizability 24 Conclusions References • • • Vlll 3 ALTERNATING FREE-RADICAL ISOMERIZATION POLYMERIZATION OF METHYL a-ISOBUTYLACRYLATE 28 Introduction 28 Experimental Section 29 Results and Discussion 30 Conclusions 37 References 38 4. INFLUENCE OF THE a-SUBSTITUENT ON THERMAL PROPERTIES AND DEGRADATION BEHAVIOR OF POLY(METHYL a-ALKYLACRYLATES) .39 Introduction... 39 Experimental Section 40 Samples 40 Measurements 40 Photodegradation Studies 40 Results and Discussion 41 Polymer Synthesis 41 Influence of Pressure and Monomer Structure on the Tacticity 42 Glass Transition in Poly(Methyl a-Alkylacrylates) 46 Thermal Stability of Poly(Methyl a-Alkylacrylates) 48 Photodegradation of Poly(Methyi a-Alkylacrylates) 51 Conclusions 53 Acknowledgements 54 References 54 5. HIGH-PRESSURE SYNTHESIS AND CONFORMATIONAL BEHAVIOR OF AMPHIPHILIC POLY(a-ALKYLACRYLIC ACID)S 56 Introduction 59 Experimental Section Materials 59 Polymerizations at High Pressure Polymer Characterization Fluorescence Measurements Results and Discussion ix Polymer Synthesis 61 Conformational Transition in Poly(a-Alkylacrylic Acid)s 63 Conclusions 66 Acknowledgements 67 References 67 6. POLYMERIZATION OF FUNCTIONAL a-SUBSTITUTED ACRYLATES DERIVED FROM BAYLIS-HILLMAN ADDUCTS 70 Introduction 70 Experimental Section 72 Materials 72 Polymerizations at High Pressure 74 Measurements 74 Results and Discussion 75 Monomer Synthesis 75 High-Pressure Polymerizations 76 Synthesis of Chiral Poly(a-Substituted Acrylates) 81 Conclusions 83 References 84 7. CONTROLLED/LIVING FREE-RADICAL POLYMERIZATION OF STERICALLY HINDERED ACRYLIC MONOMERS UNDER HIGH PRESSURE 86 Introduction 86 Experimental Section 87 Materials 87 Polymerizations 88 Measurements 88 Results and Discussion 88 Polymerization Kinetics 88 End-Group Analysis ^'7 Synthesis of Block Copolymers Conclusions X References 99 8. SYNTHESIS OF WELL-DEFINED POLY(ETHACRYLIC ACID) BY HIGH-PRESSURE RAFT POLYMERIZATION 101 Introduction 101 Experimental Section 102 Materials 102 Polymer Synthesis 103 Measurements 103 Results and Discussion 104 Conclusions 109 Acknowledgements 1 10 References 110 9 SYNTHESIS OF LIVING POLYMERS OF ULTRA-HIGH MOLECULAR WEIGHT BY A FREE-RADICAL POLYMERIZATION TECHNIQUE 112 Introduction 1 12 Experimental Section 1 14 Materials 1 14 High-Pressure Polymerizations 1 14 Measurements 114 Results and Discussion 115 Conclusions 121 References 121 10. CONTROLLED SYNTHESIS OF POLY(MACROMONOMERS) BY HIGH-PRESSURE RAFT POLYMERIZATION 123 Introduction 123 Experimental Section 125 Materials Synthesis of Polystyrene Macromonomers 125 High-Pressure Polymerizations 125 Measurements Results and Discussion xi Synthesis ofMacromonomers 126 HP-RAFT Polymerization of PS-MA Macromonomer 127 Synthesis of Block Copolymers Based on Poly(PS-MA) 130 Conclusions 133 References 134 APPENDIX: MALDI-TOF MASS SPECTROMETRIC ANALYSIS OF END-GROUP TRANSFORMATION IN PMMA OBTAINED BY RAFT POLYMERIZATION 136 BIBLIOGRAPHY 143 xii LIST OF TABLES Table - p^g^ 2.1 Polymerization results for a-alkylacrylates at high pressure 18 2.2 Kinetic parameters for the polymerization of a-alkylacrylates 21 4. 1 Polymerization conditions and molecular weight characteristics of the poly(methyl a-alkylacrylates) used in this study 42 4.2 Stereochemical characteristics of poly(methyl a-alkylacrylates) 45 4.3 Glass transition temperatures of poIy(methyl a-alkylacrylates) and corresponding poly(alkyl methacrylates) 48 5.1 Polymerization of a-alkylacrylic acids at high and atmospheric pressures 61 5.2 Transition pH values for poly(a-alkylacrylic acid)s 66 6.1 Polymerization results for a-substituted acrylates 1, 2, and R-1 77 7. 1 High-conversion RAFT polymerization of methyl ethacrylate MEA under high pressure conditions 91 7.2 Polymerization of styrene initiated by poly(MEA)-dithiobenzoate 97 8.1 RAPT polymerization of ethacrylic acid and its derivatives under high pressure conditions 105 9. 1 RAPT polymerization of MMA under high-pressure conditions 116 1 0. 1 High-pressure RAPT polymerization of PS-MA 129 xiii LIST OF FIGURES ^'^'^ ' Page 2. 1 Polymerizability factor as a function of pressure for methyl a-alkylacrylates (65 °C, bulk, AIBN): MEA(a), M«BA(«), M/BA(b), M/PA(4) 20 2.2 Dependence of the overall rate coefficients
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