Cross-Linked Supramolecular Polyurea Elastomers with Mechanical Robustness and Recyclability.

Cross-linked polymers are indispensable in advanced applications, but suffer from poor recyclability due to permanent covalent networks. Herein, we report recyclable supramolecular polyurea elastomers that integrate ureidopyrimidinone-based quadruple hydrogen-bonding motifs directly into the polymer backbone. The dynamic and reversible nature of these motifs imparts the SPUEs with remarkable malleability and reprocessability while preserving the robustness of conventional polyureas. The SPUEs display remarkable mechanical robustness, solvent resistance, and facile reprocessability through hot-pressing, producing homogeneous films with minimal performance loss. Impressively, tensile strength, elongation at break, and toughness retained high recovery after reprocessing, demonstrating excellent closed-loop mechanical recyclability. This work showcases supramolecular engineering as a powerful strategy to reconcile mechanical robustness with recyclability in cross-linked polymers, offering new opportunities for sustainable thermosets and elastomers in circular materials design.