Synthesis and applications of depolymerizable polyaldehydes

Abstract

Depolymerizable polymers are stimuli-responsive materials that can be triggered to rapidly and completely depolymerize into their constituting monomers on command. Their applications include use in triggered release, recyclable and restructurable materials, disappearing or transient materials, and many others functions. Polyaldehyde materials were selected as a candidate system for study due to their known ability to depolymerize rapidly; however, they are also known to generally suffer from limited synthetic accessibility and sensitivity toward post-polymerization modification, thus restricting widespread adoption. My research has broadly focused in two areas: Chapters 2-5 focus on the development of a general and scalable cationic polymerization and copolymerization of aldehydes; Chapters 6-7 describe the installation of functional handles for post-polymerization elaboration of polyaldehydes into various nanostructures. Chapter 8 includes more recent work aimed at the preparation of a novel class of sustainable, recyclable, and eco-friendly depolymerizable polyesters. In short, the cationic polymerization of aldehydes was found to be a robust and scalable reaction, and mechanistic analysis of the polymerization has revealed a reversible cyclization process that produces macrocyclic architectures in high yield and with high purity. It was also found that copolymerization of o-phthalaldehyde with substituted benzaldehydes, generally considered unreactive to polymerization, yielded stimuli-responsive polyaldehyde materials that could be further elaborated to generate depolymerizable single-chain polymeric nanoparticles and polymer networks. These and other studies on the preparation and development of depolymerizable materials have advanced the state-in-the-art in polyaldehyde synthesis and paved the way for new applications in triggered depolymerization