Cycloreversion-Enhanced Toughness and Degradability in Mechanophore-Embedded End-Linked Polymer Networks

Enhancing the toughness while achieving triggerable degradation in single-network polymer systems without modify-ing their inherent chemical composition or network architecture remains a significant challenge. Here we demonstrate a smart end-linked polymer network that "self-strengthen" during use yet "self-destruct" upon certain stimuli. Embedding nonscissile cyclobutane-fused tetrahydrofuran mechanophores within the middle of end-linked polymer networks sig-nificantly enhances both toughness and degradability. Under mechanical stress, the force-coupled cycloreversion of these mechanophores releases concealed chain segments, allowing the single-network materials to stretch 100% further and exhibit tear energies nine times higher than conventional counterparts. Additionally, ball-milling griding of the bulk material unveils acid-sensitive enol ether units, leading to a markedly improved degradation profile under acidic condi-tions. This dual effect—originating from the force-coupled cycloreversion of cyclobutane-fused tetrahydrofuran mech-anophores—provides an ideal combination of superior mechanical performance and on-demand degradability.