Part I: Strategies for the Controlled Chain Growth Synthesis of Electron Deficient Conjugated Polymers Part II: Synthesis of Solution Suspendable Gold Nanotubes and Their Shape Dependant Optical Properties

This dissertation will be presented in two parts. Part I describes synthetic strategies for synthesizing electron deficient conjugated polymers using controlled chain growth methods. Part II describes the synthesis of solution suspendable gold nanotubes using a templated electrochemical synthesis and their optical properties. Chapter 1 serves as an introduction to controlled chain growth synthesis of conjugated polymers using catalyst transfer polymerizations (CTP). In particular, this introduction focuses on the limited efficacy of CTP on electron deficient monomers, and speculation as to why this is the case based on our understanding of the CTP mechanism. Chapter 2 presents the first controlled chain growth synthesis of an electron deficient conjugated polymer. The key reaction intermediate for CTP is an association complex between the monomer and catalyst. This intermediate is modeled using computational chemistry, and its strength is correlated to how well a polymerization adheres to the controlled chain growth mechanism. Chapter 3 is an extension of the concepts developed in chapter 2. Using computationally guided catalyst design, we target a nickel(II) diimine catalyst that can coordinate strongly to both electron rich (donor) and electron deficient (acceptor) monomers. We study the polymerization kinetics for both monomer types and present the first controlled chain growth synthesis of a donor-acceptor block copolymer. Chapter 4 briefly presents the idea of switchable polymers and its relation to conjugated polymers. We synthesize a polyselenophene that is capable of converting from electron rich to electron deficient using post polymerization functionalization. The effect this conversion has on the optical, electronic, and crystalline properties of these two polymers is compared. Chapter 5 is an introduction to the fields of plasmonics, the optical characteristics of metal nanoparticles, and refractive index sensing using gold nanostructures. Following that, an introduction to the application of anodic aluminum oxide (AAO) membranes as templates for the electrochemical synthesis of metal nanostructures. Lastly, a description of our custom methods and apparatus used in all syntheses carried out in Part II. Chapter 6 discusses the templated electrochemical synthesis (TES) of solution suspendable gold nanotubes using AAO membranes. Gold nanotubes can be synthesized by depositing gold shells around a sacrificial hydrophobic polymer core within an AAO membrane. Using AAO membranes as templates inherently allows control over the diameter of the resulting nanostructure, however we show that the length is controlled by deposition time, and by varying polymer core hydrophobicity we can control the gold shell thickness. Chapter 7 describes the size and shape dependant optical properties of both aligned arrays and solutions of gold nanotubes. Solution suspended gold nanotubes exhibit two optical absorbances in the visible, near infra-red (IR) range, both of which show extraordinarily high sensitivity to changes in refractive index when compared to analogous gold nanorods. This chapter concludes by describing preliminary work on the molecular sensing capability of solution suspendable gold nanotubes. Chapter 8 presents the future outlook for these fields of research

Keywords: Catalyst Design
Conjugated Polymers
Materials Science
Nanotube
Advisor: Seferos, Dwight S