Design and synthesis of acid-cleavable monomers for chemically degradable polymeric materials

Synthetic polymers are extremely abundant in the modern world, being found in nearly every industry due to their versatile properties and ease of mass production. However, due to limitations of existing recycling methods, the vast majority of these materials are disposed of in landfills at the end of their lifetime, causing adverse environmental effects. Thus, there is great interest in developing polymeric materials that can undergo on-demand room temperature chemical degradation, allowing for subsequent chemical recycling or upcycling. This dissertation focuses on a degradation mechanism termed CyclizAtion-Triggered CHain (CATCH) cleavage, in which an acyclic acetal is kinetically and thermodynamically trapped by a nearby pendant hydroxyl group in acidic conditions. The mechanism of CATCH cleavage was investigated through kinetics experiments, and CATCH-based monomers were synthesized and used to prepare several thermosets that degraded rapidly at room temperature. Modifying the electronics of the acetal substituent resulted in vast differences in small molecule degradation rates, but this tunability was more challenging to achieve in thermosets due to the added structural complexity of polymer networks. Aiming to improve upon the existing CATCH degradation procedure, which requires the addition of organic solvent and acid, photoacid generation was explored as a potential new direction. In this approach, CATCH-cleavable polymers would also contain their own masked acid source, resulting in a cascade degradation initiated by UV light. A variety of ortho-nitrobenzyl derivatives were designed, synthesized, and investigated as potential candidates for incorporation into polymers. Upon irradiation at 365 nm, a photoacid-generating diyne monomer released methanesulfonic acid in situ that initiated rapid CATCH cleavage of a diazide monomer in a small molecule degradation study. Further optimization of the polymerization conditions is still needed to evaluate the success of this methodology in polymeric systems, and modifications to the monomer design may be required to reduce the rate of undesired side reactions during polymerization. However, the late installation of the polymerizable functionalities in the monomer syntheses allows for several moieties to be screened easily, thus broadening the scope of potential applications for this work.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Paterson, Mara

Contributors dc:contributor

• Zimmerman, Steven C
• Guironnet, Damien S
• Chan, Jefferson K
• Evans, Christopher M

• Polymers
• Acetal
• Catch Cleavage
• Polyurethane
• Upcycling
• Recycling
• Thermosets
• Photoacid
• Degradation

Statement dc:rights

• Copyright 2024 Mara Louise Paterson

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/125757

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F125757