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Rheology of Associating Polymers: Effects of Ionic And RHEOLOGY OF ASSOCIATING POLYMERS: EFFECTS OF IONIC AND HYDROGEN BONDING INTERACTIONS by Tanja Tomkovic Diploma, The University of Belgrade, 2012 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Chemical and Biological Engineering) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) July 2019 © Tanja Tomkovic, 2019 The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the dissertation entitled: Rheology of Associating Polymers: Effects of Ionic and Hydrogen Bonding Interactions submitted by Tanja Tomkovic in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Faculty of Graduate and Postdoctoral Studies Examining Committee: Dr Savvas Hatzikiriakos Supervisor Dr Laurel Schafer Co-supervisor Dr Milana Trifkovic External Examiner Dr Stavros Avramidis University Examiner Dr Peter Englezos University Examiner Additional Supervisory Committee Members: Dr John Frostad Supervisory Committee Member Dr Anthony Wachs Supervisory Committee Member ii Abstract Associating polymers, consisting of relatively small functional groups capable of forming reversible physical associations, represent an important class of materials since they can be used in stimuli-responsive systems. They have found numerous applications in self-healing systems, and they can be used as shape memory polymers and biomaterials. Their complex behavior depends on the delicate interplay between the chemistry of functional groups and polymer dynamics. Therefore, it is essential to understand the physics of these complicated networks to exploit their full potential for important/innovative applications. Two classes of associating polymers, namely ion-containing polymers (ionomers), and hydrogen bonding polymers, were studied. Using a rotational rheometer and the Sentmanat extensional fixture, a full rheological characterization of several commercial ionomers and a series of novel amine-containing polynorbornenes and polycyclooctenes was conducted. Emphasis has been placed on the distribution of the relaxation times to identify the characteristics times such as reptation, Rouse times and the characteristic lifetime of the ionic and hydrogen bonding associations. These characteristic relaxation times were related to the structure of these polymers using developed scaling theories. Complete removal of ions was performed to produce copolymers in order to study the relative effects of ionic associations. It was demonstrated that ionic interactions increase the linear viscoelastic moduli and the viscosity by up to an order of magnitude and cause significant strain hardening effects in uniaxial extension. Similarly, for the novel hydrogen bonding polymers, the reversible associations significantly increase the rheological properties and thus delay their relaxation, causing chains to strain-harden before failure. Additionally, it was discovered that the iii amine-containing polymers exhibit outstanding self-healing properties. Optimal, fast self-healing response was achieved by varying the molecular weight and structure of these materials. Finally, the capillary flow of several commercial ionomers was studied both experimentally and numerically. The excess pressure drop due to entry, the effect of pressure on viscosity, and the possible slip effects on the capillary data analysis were examined. Rheological data were successfully fitted to a viscoelastic model developed by Kaye, Bernstein, Kearsley, and Zapas, (known as the K-BKZ model) to perform relevant capillary flow simulations. iv Lay Summary Two classes of associating polymers were studied in this thesis. One group possesses strong ionic associations (ionomers) and the second group has hydrogen bonds (polynorbornenes and polycyclooctenes). The goal was to study the flow properties (rheology and dynamics) of these materials and relate them to their molecular characteristics. Additionally, important applications emerged for the polymers used in this work. First, for the ionomers, this study has shown a way to process them and investigate their flow behavior numerically by using an integral model. This model was capable of capturing both the rheological and flow behavior accurately. Based on this work, the model can further be used to simulate the behavior of ionomers in other processing operations, such as injection molding and film blowing. In addition, the polycyclooctenes developed in this work were found to exhibit a remarkably fast self-healing behavior and equally fast recovery of their mechanical properties after fracture/failure. v Preface Some parts of this thesis are reproduced with permission from the published research articles. Chapter 2. Sample preparation and experimental procedures are partially taken from the following publications: T. Tomkovic and S.G. Hatzikiriakos, J. Rheol., (2018), 62, 1319; T. Tomkovic et al., J. Non-Newtonian Fluid Mech., (2018), 262, 131; T. Tomkovic et al., Phys. Fluids, (2019) 31, 1; Provisional patent app. UBC-18-076 “Amine-functionalized polyolefins and methods of preparation and use thereof”. Chapter 3. Most of this chapter has been previously published as T. Tomkovic and S.G. Hatzikiriakos, J. Rheol., (2018), 62, 1319. Both authors participated and designed the research. I did all the experimental work and the analysis of the data in terms of a scaling theory to extract the characteristics times of the relaxation with some guidance from professor S.G. Hatzikiriakos. Chapter 4. Most of this chapter has been previously published in two research articles. T. Tomkovic et al., J. Non-Newtonian Fluid Mech., (2018), 262, 131; T. Tomkovic et al., Phys. Fluids, (2019) 31, 1. I performed all experimental work, analysis of the data, and the fitting using the K-BKZ model with some guidance from professor S.G. Hatzikiriakos. Professor E. Mitsoulis run all numerical simulations. Chapter 5. Some parts are used for the papers to be submitted for publication with guidance from both professor S.G. Hatzikiriakos and professor L.Schafer. Synthesis of functionalized polynorbornenes had been performed by N. Kuanr as well as the molecular characterization of these polymers. Some experimental results of functionalized polycyclooctenes have been published in the Provisional patent app. UBC-18-076 “Amine-functionalized polyolefins and methods of preparation and use thereof”. D. Gilmour synthesized these polymers and carried out vi the molecular characterization. For both polymers, I did all thermal and rheological characterization as well as the self-healing experiments. vii Table of Contents Abstract ......................................................................................................................................... iii Lay Summary .................................................................................................................................v Preface ........................................................................................................................................... vi Table of Contents ....................................................................................................................... viii List of Tables .............................................................................................................................. xiv List of Figures ............................................................................................................................. xvi List of Symbols ......................................................................................................................... xxiv List of Abbreviations .................................................................................................................xxx Acknowledgments ................................................................................................................... xxxii Dedication ............................................................................................................................... xxxiv Chapter 1: Introduction ................................................................................................................1 1.1 Definition, Characteristics, and Application of Associating Polymers .......................... 2 1.2 Ionomers ......................................................................................................................... 3 1.2.1 Definition of Ionomers ................................................................................................ 4 1.2.2 Preparation and Composition of Ionomers ................................................................. 4 1.2.3 Morphology of Ionomers ............................................................................................ 6 1.2.4 Thermal, Physical, and Mechanical Characteristics of Ionomers ............................... 8 1.3 Amine-Containing Polymers .......................................................................................... 9 1.3.1 Hydrogen Bonding ...................................................................................................... 9 1.3.2 Functionalized Polynorbornenes ............................................................................... 11 1.3.3 Functionalized Polycyclooctenes .............................................................................. 13 viii 1.4 Rheological Properties of Associating Polymers .........................................................
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