The thesis work described herein explores two avenues of post-functionalization of conjugated polymers using ‘click’ chemistry. The first avenue utilizes the Strain-Promoted Alkyne-Azide Cycloaddition (SPAAC) and the second an Inverse Electron-Demand Diels-Alder (IEDDA). In the first part of this thesis, various azide moieties were SPAAC ‘clicked’ onto a dibenzocyclooctyne-containing polymer, such as small molecules like para-phenyl-nitroazide, as well as larger azide-terminated chains like polystyrene and polyethylene glycol. Host-guest chemistry and self-healing organogels were also explored. The synthesis of each component, including the cyclooctyne diamine monomer, dialdehyde comonomer, resulting polymer, various azide moieties, as well as the SPAAC click reactions, are all described in detail along with extensive characterization. Similarly, the second part of this thesis involved the synthesis and characterization of several components, including the tetrazine monomer, fluorene comonomer, resulting polymer, and various TCO derivatives for the post-polymerization IEDDA ‘click’ reactions onto the backbone. Some of the click reactions described include small molecule TCO derivatives, polymeric PEG TCO, and a difunctional linker to generate a crosslinked foam. / Conjugated polymers attract significant attention due to their interesting optoelectronic and physical properties. Over the past few decades, tremendous effort has been devoted to expanding the structural diversity and applications of this class of macromolecules. The pursuit of structural variability of conjugated polymers has resulted in a broad range of research to understand their structure-property relationships via functionalization. This functionalization is crucial for tailoring performance in any given application. Thus, the ability to synthesize a library of homologous polymers would prove very useful. Efficiency is of utmost importance when creating a library of homologous conjugated polymers, as the faster a library can by synthesized, the sooner said polymers can be screened for any desirable properties. Such an approach requires a post-polymerization functionalization strategy, whereby a progenitor polymer undergoes efficient reactions at each repeat unit of the backbone.
The work presented in this thesis involves synthesizing a reactive conjugated polymer scaffold, followed by efficiently post-polymerization functionalization via “click” chemistry. Two elegant click reactions are described in this work; the Strain-Promoted Alkyne-Azide Cycloaddition (SPAAC) and Inverse Electron-Demand Diels-Alder (IEDDA). The SPAAC reaction allowed for rapid functionalization of triazole moieties on a dibenzocyclooctyne-containing polymer backbone, creating a small polymer library with a consistent degree of polymerization (DP). Grafting with polystyrene and polyethylene glycol azide-terminated polymers allowed the efficient syntheses of a series of graft-co-polymers with Mn values up to 800 kDa and varying solubilities. Secondly, The IEDDA reaction was applied to a poly(tetrazine-co-fluorene) conjugated polymer, which resulted in the rapid and quantitative functionalization of the polymer backbone with trans-cyclooctene derivatives. These reactive conjugated polymers were explored in a variety of applications, including supramolecular chemistry and gel formation. / Thesis / Doctor of Philosophy (PhD) / Conjugated polymers are a class of macromolecular materials that attract significant attention due to their interesting behaviors and properties. Under certain conditions, these polymers even display conductivities like that of metals. As such, they show promise in applications such as organic solar cells, chemical sensors, organic light-emitting diodes, and supercapacitors. Over the past few decades, tremendous effort has been devoted to expanding on the types of conjugated polymers as well as their structural diversity. This, of course, has resulted in polymers that exhibit vastly different behaviours depending on what they are made of. As certain applications (e.g.: solar cells) require polymers with very specific properties, being able to ‘tune’ a conjugated polymer to ‘match’ a required property would be extremely useful. This tuning of polymer properties can be successfully accomplished by attaching different structures onto the polymer chain by utilizing a reaction known as ‘post-polymerization functionalization’. In doing so, a starting reactive polymer can be transformed into an entirely different polymer with specific chemical properties and behaviors.
The work presented in this thesis involves synthesizing two types of conjugated polymers and attaching various structures onto their backbones to yield different properties. The synthesis, characterization, and potential applications of said polymers are described herein.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/27277 |
| Date | January 2021 |
| Creators | Kardelis, Vladimir |
| Contributors | Adronov, Alex, Chemistry and Chemical Biology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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