Doctor of Philosophy, Miami University, 2019, Chemistry and Biochemistry

Using dynamic chemistry to develop functional polymers is an emerging area in material science. This class of polymers possesses intrinsic reversibility owing to the covalent or noncovalent bonds within, therefore respond to external stimuli. In addition, combining dynamic interactions with polymers offers exciting dynamic features such as environmental adaptivity, malleability, self-healing, and shape memorizing properties. Noncovalent interactions, e.g., hydrogen bonds, metal-ligand coordination, host-guest interactions, ionomers or π-stacking, have been successfully built into polymers over the last decades. Researchers have also relied on dynamic covalent bonds, e.g., Diels-Alder adducts, disulfide exchange, imine bonds, or boronic ester bonds. However, the underlying kinetics of some covalent interactions have not been demonstrated explicitly. Besides, the dynamic nature of the crosslinkers introduces the potential for the material not only the weak toughness but also to creep or deform over time under load. Recently, a combination of dynamic and static crosslinkers on either the main polymer chains or side chains with different structures has been used to overcome these limitations and enhance the mechanical properties. Other than that, materials containing orthogonal dynamic chemistries enable the synthesis of intricate macromolecules which can respond to multiple stimuli to achieve the desired response. Our work mainly focuses on a deep understanding of the mechanism of the covalent interactions in terms of small molecule models to better manipulate them in the bulk polymers, making new dynamic materials, and exploring the impact of the macromolecular architectures on their properties. A mechanistic study of the thermally activated dynamic covalent chemistry of thiol-Michael adducts is the focus of Chapter two, using a model system of thiophenol/mercaptoethanol dynamic equilibrium with phenylvinylketone based Michael acceptors. Chapter three works on f (open full item for complete abstract)

Committee: Dominik Konkolewicz (Advisor); Scott Hartley (Committee Chair); Richard Taylor (Committee Member); Gary Lorigan (Committee Member); Jessica Sparks (Committee Member) Subjects: Chemistry; Materials Science; Organic Chemistry; Physical Chemistry; Polymer Chemistry; Polymers