A Tert-Alkyl Terephthalate Derivative as a Universal Degradable Unit for Condensation Polymers

Incorporating cleavable triggers into the backbones of parent polymers enables programmed degradation, offering a pathway to chemically recyclable plastics. Although various triggers have been reported to date, simple esters bearing a C─O bond cleavable by photocatalytic reactions have not been successfully employed as triggers. This is because the C─O bond of simple esters is inert. In this study, we demonstrated that efficient ester C─O bond cleavage can be achieved by generating a stable tertiary alkyl radical upon bond scission. Based on this principle, we designed a dicarboxylic acid core featuring a tertiary alkyl ester incorporated into a terephthalic acid scaffold. The designed core was incorporated into polyarylate, polyurethane, and polyester, and all three polymers underwent selective C─O bond cleavage of the tertiary alkyl ester under identical photocatalytic conditions, achieving degradation efficiencies of up to 99% within 2-4 h. Unlike conventional hydrolysis, our method selectively cleaves only the targeted ester bond, leaving others intact. This yields fewer, simpler products and greatly simplifies monomer recovery. Notably, our degradable polymers retained physical properties comparable to parent plastics despite trigger incorporation.