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The Utility and Development of Brønsted Acids for Advanced Functional Material

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Abstract

Proton driven processes are one of the most ubiquitous chemistries found and are present across many different disciplines. Brønsted acids provides the ability to selectively regulate the extent of proton transfer offering a myriad of possibilities by controlling reaction kinetics, proton gradients, and chemical environment. As such, we can take advantage of one of the most fundamental processes in chemistry to help us better study and develop the emerging class of advanced functional materials. In this dissertation, I will highlight the projects I’ve led in this area. Beginning with a fundamental study on the effect of acid strength in polymeric protic ionic liquids (polyPILs), I will demonstrate a direct correlation with ionic conductivity as a function of the Brønsted acid’s pKa. Furthermore, the ionic nature of these systems is explored using pulse field gradient NMR demonstrating how the extent of proton transfer directly correlates to the ΔpKa of the constituent acid-base pair. The density field theory calculated physicochemical values correlate closely with the experimentally obtained data suggesting that pKa can be used as metric to approximate ion pair strength/lifetime association in polyPILs. Next, I will discuss the development of a new merocyanine-based photoacid, which demonstrates improved solubility in organic media and enhanced switching kinetics that can be used to impart temporal control over ring opening polymerization. The effect of the structural modification on solubility, thermal relaxation kinetics, and activation energy were evaluated using 1H NMR and pump-probe absorption spectroscopies. Overall, the new merocyanine based photoacid provides access to a wider range of chemical and material applications with improved solvent compatibility and temporal control. Finally, I will discuss how we developed a Brønsted acid catalyzed dynamic covalent chemistry using commodity polymers. Herein, a novel triblock polyester system is prepared from the chain extension of readily available commercial polymers. With a newly developed bis-lactone crosslinker and the merocyanine photoacid previously discussed, a photo-curable resin is demonstrated, highlighting the potential for various applications including photo-patterning and additive manufacturing. Altogether, I hope this dissertation will demonstrate the effective value Brønsted acids have in the development of advanced functional materials.

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This item is under embargo until October 22, 2023.