Thermo-responsive Graft Copolymers based on Poly(Methyl Vinyl Ether) : from Synthesis to Evaluation Ondine Confortini Promotor : Prof. Dr. Filip Du Prez GHENT UNIVERSITY Faculty of Sciences Department of Organic Chemistry Polymer Chemistry Research Group Academic Year 2008-2009 Thesis submitted to obtain the grade of Doctor in Sciences: Chemistry Thermo-responsive Graft Copolymers based on Poly(Methyl Vinyl Ether) : from Synthesis to Evaluation Ondine Confortini Polymer Chemistry Research Group Department of Organic Chemistry Ghent University Belgium ACADEMIC DISSERTATION Thesis submitted to obtain the degree of Doctor in Sciences: Chemistry To be presented with the permission of the Faculty of Science of the Ghent University for public criticism in Auditorium A of the Department of Organic Chemistry, on April 30th, 2009, at 15h00. Ghent 2009 Supervisor Professor Filip Du Prez Polymer Chemistry Research Group Ghent University Belgium Reviewers Professor Heikki Tenhu Laboratory of Polymer Chemistry University of Helsinki Finland and Professor Bruno Van Mele Department of Physical Chemistry and Polymer Science Free University of Brussels Belgium Jury Professor Filip Du Prez (promoter, UGent) Professor Heikki Tenhu (University of Helsinki, Finland) Professor Bruno Van Mele (Free University of Brussels, Belgium) Professor Em. Eric Goethals (UGent, Belgium) Professor Peter Dubruel (UGent, Belgium) Acknowledgments First of all, I wish to express my deepest gratitude to my supervisor, Professor Filip Du Prez for offering me the opportunity to take part in this project, which opened the doors of the fascinating world of nanotechnology. While allowing me considerable freedom, he also teached me how to manage it. I will keep an unforgettable memory of the solid scientific methodology he taught me. I am grateful for his scientific guidance, encouragement, and patience during these years. I wish to thank him for offering me the possibility to spend the most instructive and challenging period of my life in Ghent. I am grateful to Professor Em. Eric Goethals for having welcomed me as a foreign master student, for the possibility to start to work in his laboratory, and for learning me to write my first international publication. I am grateful to Professor Jean-Paul Laîné in the University of Rouen who found me my master training in Ghent, which finally permitted me to obtain the degree of Doctor in Sciences with Professors Eric Goethals and Filip Du Prez. It is an honour for me that Professor Heikki Tenhu and Professor Bruno Van Mele accepted to be the reviewers of this work. I thank Professors Eric Goethals and Peter Dubruel for the examination of this work and I am pleased that Professor Katrien Strubbe is the president of this jury. This manuscript is the result of numerous collaborations that made the realization of an interdisciplinary study possible. I am very grateful to Professor Heikki Tenhu in the University of Helsinki for offering me the excellent facilities in Dynamic Light Scattering (DLS), High Sensitivity Differential Scanning Calorimetry (HS-DSC) and Pressure Perturbation Calorimetry (PPC). I am also grateful to Dr. Vladimir Aseyev for offering me his expertise in DLS, and Dr. Antti Laukkanen for HS-DSC and PPC. Your guidances in editing the manuscripts were most helpful! I am very grateful to Professor Bruno Van Mele in the Free University of Brussels for his interest in my work and for offering me the opportunity to characterize the thermo-responsive properties of my graft copolymers by Modulated Temperature Differential Scanning Calorimetry (MTDSC). I also thank him for the constructive and interesting criticism of the manuscript. I would also like to thank Dr. Kurt Van Durme, Dr. Jun Zhao and Dr. Guy Van Assche for all the help with the measurements by MTDSC. I specially thank Professor Rudy Willem and Dr. Monique Biesemans in the Free University of Brussels for their valuable discussion and help concerning the evaluation of the grafting degree of my graft copolymers, and who permit me to use their MATLAB program. I would also specially thank Professor Uwe Beginn in the University of Aachen in Germany for his long discussion about the different methods to determine the monomer reactivity ratios and who permits me to used his BASIC program. I would like to thank Professor Etienne Schacht and Dr. Veska Toncheva in UGent for the critical aggregate concentration (CAC) measurements, and Mr Roeland Myngheer for the PEO synthesis. I would like to thank Professor V. Zubov and Dr. N. Bulychev in the Universtity of Moscow for his interest in my work and for the dye stabilization of my PMVE-g-PEO/water system. I also wish to thank my short-term colleagues in the University of Helsinki for making my stay very enjoyable by creating a friendly and helpful atmosphere in the laboratory. I will never forget this typical Sauna party! I would like to thank all the former and current members of the Department of Organic Chemistry: Professors, technicians and colleagues, for making it such a pleasant place to work. Especially thanks to Beatrice Verdonck and Peggy Van De Velde who learned me the base of the polymer synthesis and the living cationic polymerization. I wish to thank Nadya, Laurence, Céline, Malgosia, Dilek, Dennis, Tianzhu and Irene for their friendship. Finally, I wish to owe my warmest thanks to my parents, Jacques and friends for their endless love, encouragement and belief in me. Financial support from UGent and the European Scientific Foundation (ESF) are gratefully acknowledged. Brussels, April 2009 Ondine Confortini Introduction and Aim…………………………………………………………………………….…………………………………… 1 PART I : Functionalized Random Copolymers of Hydrophilic and Hydrophobic Vinyl Ether Monomers Obtained by Living Cationic Copolymerizations…………………………………………………………………………………………………………………………. 9 Content of Part I……………………………………………………………………………………………………………………………………. 10 Abstract……………………………………………………………………………………………………………………………………………………. 12 Chapter 1 : Theory of Living Cationic Polymerization of Vinyl Ethers……………………………….. 13 Chapter 2 : Theory of the Determination of the Reactivity Ratios of Random Copolymers……………………………………………………………………………………………………………………………………………….. 31 Chapter 3 : Synthesis of Vinyl Ether Copolymers by Cationic Copolymerizations………….… 41 PART II : Design of Novel Thermo-responsive Poly(Methyl Vinyl Ether)-g-Poly(Ethylene Oxide) Graft Copolymers via the ‘Grafting onto’ Method………………………………………………………………………………………………………………………..…………… 75 Content of Part II…………………………………………………………………………………………………………………………………. 76 Abstract……………………………………………………………………………………………………………………………………………………. 78 Chapter 4 : Theoretical Aspects of Graft Copolymers……………………………………………………………. 79 Chapter 5 : Synthesis and Molecular Characterization of Poly(Methyl Vinyl Ether)-g- Poly(Ethylene Oxide) Graft Copolymer……………………………………………………………………………………….….. 89 Chapter 6 : Thermo-responsive Properties of PMVE-g-PEO Graft Copolymers…………...... 105 PART III : Well-defined Stimuli-responsive Graft Copolymer Structures by Combination of the ‘Grafting From’ Method and ATRP…. 143 144 Content of Part III………………………………………………………………………………………………………………………….……. Abstract……………………………………………………………………………………………………………………………………………………. 146 Chapter 7 : Theory of Controlled Radical Polymerization………………………………………………….……. 147 Chapter 8 : Synthesis of Poly(Methyl Vinyl Ether) based Graft Copolymers via ‘Grafting From’ Method…………………………………………………………………………………………………………………….…. 161 Chapter 9 : Properties of Thermo-responsive PMVE-g-PS Graft Copolymer……………….….. 191 PART IV : Experimental Part………………………………………………………………………………….…………… 207 Content of Part IV……………………………………………………………………………………………….………………………….……. 208 IV.1. Reagents and Materials………………………………………………………………………………………………………….. 209 IV.2. Analytical Methods: Measurements………………………………………………………………………..………….. 211 IV.3. Syntheses………………………………………………………………………………………………………………..………………….. 225 Conclusion……………………………………………………………………………………………………………………..……………………. 241 Appendix I : COPOINT Program……………………………………………………………………………………………………. 249 Appendix II : Basic Program for the Tidwell-Mortimer Method……………………………………… 251 Appendix III : Determination of the Degree of Functionalization of PMVE-g-PEO by Elemental Analysis and the Non-linear Least-squares Analysis…………………………………………… 253 Appendix IV : Abbreviations 259 INTRODUCTION What is strongest than the stone or softest than water? Nevertheless, soft water corrodes the stone so strong. The perseverance. Ovide Introduction and Aim Introduction and Aim Introduction The range of research into the so-called stimuli-responsive polymers, also referred to as smart polymers, has been considerably extended in recent years. Investigations in this area are at the leading edge of modern science [1-7]. Smart polymers are polymers that undergo reversible sharp physical or chemical modifications in response to specific changes in their environment (figure I1, table I1). The microscopic changes are apparent at the macroscopic level as precipitation formation in a solution or an order of magnitude decrease or increase in hydrogel size or solvent content. As living processes are based on such responses to stimuli, these smart macromolecules are the compounds of choice to study and mimic biological systems. Therefore, a lot of research work has been devoted to the conception of stimuli-responsive polymers used in composite systems responding to temperature, pH, ionic strength, chemicals, electric or magnetic fields, light, etc. Stimuli-response Stimulus Figure I1. Sketch of smart