Single-walled carbon nanotubes (SWNTs) have excellent electronic, mechanical, and optical properties that make them promising materials for various applications. However, SWNT production methods produce a mixture of semiconducting and metallic species and non-SWNT impurities limiting their incorporation into devices. Among the different purification methods, conjugated polymer sorting has proven to be a scalable and cost-effective method. Conjugated polymers can easily be tuned to disperse SWNT species and obtain solubility in target solvents. They are multifunctional structures that enable the purification and extraction of specific SWNTs while simultaneously enhancing their processability. Therefore, they are suitable as purification methods for the fabrication of SWNT-based devices, particularly for printed electronics. However, the polymer backbone and the non-conductive side-chains negatively impacts the performance of SWNT devices by preventing good contact between the nanotubes. We first functionalized our polymer with thermally cleavable side-chains and demonstrated that the removal of the side-chains leads to a higher conductivity. We obtained stable dispersions in two green solvents compatible with inkjet printing. We also functionalized our polymer with photocleavable side-chains and showed efficient cleavage in solution. These investigations represent a proof-of-concept that could be used for the development of SWNT-based devices where the removal of the side-chains will improve the device performance. Lastly, we synthesized a fluorene-based polymer that contains a photocleavable ortho-nitrobenzylether unit and is functionalized with hydrophilic side-chains. We demonstrated the degradation of the polymer in organic and aqueous solvents. These investigations highlight the challenges of dispersing SWNTs in aqueous solvents using conjugated polymer. / Thesis / Doctor of Philosophy (PhD) / The objective of this thesis is to develop cleavable complexes between conjugated polymers and single-walled carbon nanotubes (SWNTs) to maximize the potential performance of printed devices post-processing. We functionalized a conjugated polymer with cleavable side-chains and investigated the impact on the conductivity after their removal. In addition, this work also focuses on dispersing SWNTs in green solvents that are compatible with printing processes such as inkjet printing. Lastly, we synthesized a degradable and water-soluble conjugated polymers to produce dispersant free-SWNTs.

京都大学 / 新制・課程博士 / 博士(薬科学) / 甲第24557号 / 薬科博第174号 / 新制||薬科||19(附属図書館) / 京都大学大学院薬学研究科医薬創成情報科学専攻 / (主査)教授 大野 浩章, 教授 高須 清誠, 教授 大宮 寛久 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

Material discovery and development has been playing a significant role in shaping human civilizations, by studying and improving materials for appealing observations to aid in our survival as well as to satisfy our curiosity. From the common earthly materials that give us strong building structures and hunting weapons to the Silicon Age that contributes to the creation of modern electronics and computers, the development of novel and enhanced materials continues to grow. Recently, a new field has emerged that is rapidly expanding the engineering circle; these are called nanomaterials. By shrinking bulk materials into structures with nanoscale dimensions, there is a deviation from classical physics, and quantum effects begin to dominate the properties of these materials. The nanometer range brings a high surface area-volume ratio which enhances the reactivity of the material, and thus size-dependent properties are materialized. Such behaviors can be applicable in several areas such as biomedical, catalysis, optics, processing, sensing and more. Nanomaterials can be further functionalized to grant new and enhanced functions, features and capabilities needed for a specific application. This dissertation aids to explore the functionalization of 1D and 2D nanomaterials for various applications. The proposed 1D and 2D nanostructures for testing will be polymer hydrogel nanofibers and silica nanoparticulate thin films, respectively. Nanofibers are unique by acting like swollen nanoreactors to enable functionalization via aqueous absorption and reaction. Silica nanoparticulate films have high nano-porosity, which can wet the thin coating intrinsically with aqueous and organic solvents or with non-organic solvents upon additional surface chemistry modification. In this dissertation, the functionalization of 1D and 2D nanostructures with chemical compounds and metal colloids will be tested, and the performance of the nanomaterials and nanocomposites for various applications will be evaluated.

京都大学 / 新制・課程博士 / 博士(人間・環境学) / 甲第25019号 / 人博第1097号 / 新制||人||257(附属図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 小松 直樹, 教授 津江 広人, 教授 藤田 健一, 准教授 Zhao Li / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

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.

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