Self-Healing and Reprocessable Polyurethane Elastomer with Triple Dynamic Crosslinked Networks.

Chemically crosslinked polyurethane materials with excellent mechanical properties have attracted considerable attention, yet recyclability is still challenging. Herein, a self-healing and reprocessable polyurethane (PU) elastomer with triple dynamic networks was synthesized through the addition reactions of methylenediphenyldiisocyanate with polyetheramine, protocatechualdehyde, and tris(2-aminoethyl) amine, as well as the incorporation of Fe³⁺ ions. Owing to the formation of microphase-separated structure and triple dynamic networks including hydrogen bonds, Fe³⁺-catechol coordination, and imine bonds, the obtained PU elastomer exhibited excellent mechanical properties with a tensile strength of 6.40 MPa, elongation at break of 1838%, toughness of 51.16 MJ m^{- 3} and fracture energy of 154.91 kJ m^{- 2}. Importantly, the PU elastomer possessed not only high healing efficiency of 96.6% after healing at 60°C for 24 h, but also superior reprocessability with a tensile strength retention rate of 75.6% after three reprocessing cycles. Besides, owing to residual phenolic hydroxyl groups in unreacted PA, the PU elastomer also exhibited outstanding thermal-oxidative aging resistance. The findings in this work conceivably stand out as a new methodology for the preparation of functional and high-performance elastomers.