Selective photodegradation of ketone-based polymers

The photodegradation of ketones, including polyketones, by Norrish degradation pathways is well established. However, these mechanistic pathways lead to uncontrolled reactions, which in the case of plastics, result in in-complete degradation and the formation of microplastic fragments. Using an organocatalyzed thiol-yne step-growth polymerization, we developed poly(enone sulfides) that display useful properties and undergo a highly selective photodegradation into non-cytotoxic diketone and disulfide products. Model substrate reactions, sup-ported by computational modelling, revealed the molecular features that enable the selective degradative path-way to occur, implicating both radical and reactive oxygen species. The synthetic approaches for monomers and polymers are versatile and allow for the design of a range of polymer structures with divergent thermomechanical properties, with some photodegradable materials being tough thermoplastics possessing high strength and ductil-ity.