Date of Award

Spring 2020

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Polymer Science and Engineering

Committee Chair

Jason Azoulay

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Derek Patton

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Yoan Simon

Committee Member 3 School

Polymer Science and Engineering

Abstract

Thiol-ene click chemistry is a robust approach to molecularly engineering polymers for many applications. Within this work, thiol-ene click chemistry is used to fabricate thiol-ene networks for TTA-UC and to synthesize a conjugated polyelectrolyte (CPE) used as a pyrophosphate (PPi) sensor in complex aqueous media. Chapter I focuses on the synthesis and upconversion performance of rubbery networks fabricated using thiol-ene click photopolymerization. The advancement of triplet-triplet annihilation based upconversion (TTA-UC) in emerging technologies necessitates the development of solid-state systems that are readily accessible and broadly applicable. We demonstrate that thiol-ene click chemistry can be used as a facile cure-on-demand synthetic route to access elastomeric films capable of TTA-UC. Photopolymerization of multifunctional thiols in the presence of a thiol-functionalized 9,10-diphenylanthracene (DPA) emitter results in covalent DPA integration and homogenous crosslinked polymer networks. The palladium(II) octaethylporphyrin (PdOEP) sensitizer is subsequently introduced into the films through solution immersion. Upon excitation at 544 nm, green-to-blue upconversion is observed with compositional tuning resulting in an optimal upconverted emission intensity at 1.0 wt% DPA and 0.02 wt% PdOEP. The effectiveness of thiol-ene networks to function as robust host materials for solid-state TTA-UC is further demonstrated by improved photostability in air. In Chapter II, a thiol-ene click post polymerization modification is used to construct a conjugated polyelectrolyte capable of sensing pyrophosphate in a complex aqueous environment. The evolution of CPEs that transduce analyte-receptor interactions into detectable fluorescent responses in complex aqueous environments is predicated on advancements in molecular design and improved synthetic accessibility. Here, we demonstrate a simple post-polymerization modification protocol based on thiol-ene click chemistry that results in the rapid installation of sodium sulfate terminated side chains to a poly(fluorene-co-ethynyl) scaffold. The fluorescence of the resulting water-soluble CPE is quenched by Fe3+, dequenched selectively by pyrophosphate (PPi), and accurately quantifies PPi within ±6 nM in artificial seawater. The broad utility of thiol-ene click chemistry should offer the straightforward integration of diverse sensing elements.

Available for download on Thursday, May 14, 2020

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