Rational design of polymeric dispersants for nanoparticles and substrates for click chemistry using atom transfer radical polymerization

This Dissertation explores the use of polymers prepared by atom transfer radical polymerization (ATRP) as substrates for the development of structure-property correlations and new functional materials. These polymeric substrates were utilized in efficient and modular "click" reactions, as described in Chapters 2--4, and as nanoparticle surface modifiers, which is detailed in Chapters 5--7. The introductory chapter provides an overview of the advantages of using controlled radical polymerization techniques for the development of polymer-based technologies Chapter 2 describes the use of polymers prepared by ATRP to probe the effects of various experimental conditions, including ligand, solvent, and reducing agent, on click reaction rate. Low-molecular weight substrates that resemble typical polymer end groups are used as model compounds in Chapter 3 to investigate the effects of the electronic and steric environment of a click chemistry reagent on its reaction rate. The combination of ATRP with click chemistry was utilized for research described in Chapter 4 for the facile synthesis of multisegmented block copolymers. Chapter 5 begins the section on designing polymers as nanoparticle surface modifiers, and is focused on the synthesis and performance assessment of well-defined polyelectrolytes prepared by ATRP as dispersants for iron oxide nanoparticles. Amphiphilic star-shaped polymers are explored as emulsifiers and adsorbents in Chapter 6, and these complex materials are also utilized as a model nanoparticle for investigating the microbial availability of particle-bound polymer. The final chapter describes the synthesis of amphiphilic gradient copolymers, which are a unique class of materials with potential as efficient particle dispersants and stabilizers for Pickering emulsions.