CO ₂ ‐Derived Degradable Polythioester Adhesives From Proton‐Trap‐Assisted S/O Isomerization‐Driven Cationic Ring‐Opening Polymerization

ABSTRACT The development of degradable pressure‐sensitive adhesives (PSAs) holds great promise for enabling the recycling of adhesive‐containing materials. However, existing degradable PSAs are often constrained by insufficient or moderate adhesion strength, reliance on fossil‐based feedstocks, and/or incomplete degradation. Addressing these challenges requires the development of new polymerization strategies and material designs. Herein, we report a proton‐trap‐assisted S/O isomerization‐driven cationic ring‐opening polymerization of the CO 2 ‐derived thionolactone 3,6‐diethyltetrahydro‐2H‐pyran‐2‐thione, which enables the well‐controlled synthesis of high‐molecular‐weight CO 2 ‐based (co)polythioesters. The resulting materials exhibit a unique combination of high and tunable peel strength (up to 16.43 N/cm), excellent optical clarity (over 96% transmittance, low haze and low yellowness index), and the ability to undergo either complete degradation or quantitative depolymerization under mild conditions, delivering the first practical example of polythioester‐based PSAs. This study establishes a sustainable platform for PSA design that integrates robust performance with full life‐cycle management, thereby advancing the utilization of CO 2 ‐derived materials and circular polymer design.