Novel titin-inspired high-performance polyurethanes with self-healing and recyclable capacities based on dual dynamic network

It is still a huge challenge that integrating excellent mechanical performance and high healing efficiency into self-healing materials at the same time, even if numerous dynamic bonds have been explored in preparing of self-healing materials in the last 20 years. Herein, we reported a novel titin-inspired strategy to prepare the polyurethanes via introducing dual dynamic network which contained the physical cross-linking of quadruple hydrogen bonds formed by 5-(2-hydroxyethyl)-6-methyl-2-aminouracil (UPy) dimers and the covalent cross-linking of Diels-Alder (D-A) bonds. Specially, relying on the synergistic effect of the dual dynamic network, the resulting polyurethane F 50 U 50 -PU exhibited admirable mechanical performance, such as a super-high strength of 51.9 MPa, a superb toughness of 166.7 MJ/m 3 and a large elongation at break of 930%. Meanwhile, on account of the dynamic feature of quadruple hydrogen bonds and D-A bonds, the resulting polyurethane showed a high heat-induced healing efficiency of 91.2%. More importantly, the polyurethanes could be recycled by hot-pressing process to regain their initial mechanical properties and integrity. And it was also used as substrate to construct self-healing conductive device, which displayed splendid self-healing of electrical conductivity after damage. It can be envisioned that the polyurethanes with both superior mechanical performance and high healing efficiencies have great application prospect in multifarious fields.