Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemical and Biochemical Engineering

Supervisor

Gillies, Elizabeth R.

Abstract

Self-immolative polymers (SIPs) are relatively recent class of stimuli-responsive and degradable polymers that have attracted significant attention in the past several years. SIPs consist of polymer backbones and stimuli-responsive end-caps at one or both polymer termini. Upon detection of a stimulus, the decomposition of the end-cap leads to complete end-to-end depolymerization. Polyglyoxylates were introduced as a new class of polyacetal based SIPs by our group in 2014. Compared with other SIPs, polyglyoxylates have two advantages including: 1) readily available monomers and 2) low toxic depolymerization products. These advantages may allow polyglyoxylates to be used in a wide range of applications. This thesis explored the design, synthesis, and study of a series of responsive end-caps for different potential applications of polyglyoxylates. First, using the previously developed 6-nitroveratryl carbonate end-capped poly(ethyl glyoxylate) (PEtG) that responded to UV light, it was demonstrated that PEtG could depolymerize back to volatile monomer at ambient temperature and pressure. This unusual feature was used to perform a facile polymer reprogramming/recycling sequence as well as polymer patterning by a simple irradiation-evaporation sequence. Moreover, end-caps that allowed polyglyoxylates to respond to oxidizing and reducing conditions, acid, heat, multiple stimuli, and one that enabled cross-linking and UV-triggered depolymerization, were developed. Furthermore, linker end-caps were developed to conjugate PEtG with poly(ethylene glycol) to form amphiphilic block copolymers. These copolymers were self-assembled to form nanoparticles that could load and release payload molecules in response to stimuli. In addition, the hydrophobicity of PEtG was tuned by copolymerization with hydrophobic monomers to improve the nanoparticle drug loading capabilities. Lastly, triphenylmethyl end-capped PEtGs were demonstrated to undergo temperature-dependent depolymerization. Proof-of-concept studies were performed to demonstrate the potential of these polymers for smart packaging applications. Overall, the work presented in this thesis serves to expand the utility of polyglyoxylate-based SIPs for various applications through the design and synthesis of responsive end-caps and new polymer backbones.

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