Self-Healable and Reprocessable Cross-Linked Poly(urea-urethane) Elastomers with High Mechanical Performance Based on Dynamic Oxime-Carbamate Bonds

Owing to excessive energy consumption and environmental deterioration, thermosets with permanent covalent crosslinks have encountered unprecedented challenge in the sustainable development. An effective method to address this intractable problem is to construct covalent adaptive networks that contain dynamic covalent bonds. Herein, self-healable and reprocessable cross-linked poly(urea-urethane) elastomers with high mechanical performance were simply developed by introducing dynamic oxime-carbamate bonds (POUUs). The studies on nuclear magnetic resonance indicated that the sufficient exchange rather than the reversible dissociation of oxime-carbamate bonds was the key to network arrangement at elevated temperatures. Due to the incorporation of strong polar urea bonds, POUUs showed excellent mechanical performance with a tensile strength of 27.8 MPa and toughness of 52.5 MJ m^-3. The good self-healing ability of POUUs was demonstrated by the disappearance of scratches at 80 °C after 15 h. All POUUs were easily remolded (130 °C, 5 MPa) into transparent films with a maximum recovery efficiency of 80%. Furthermore, complete dissolution inN,N-dimethylformamide was achieved at 100 °C after 4 h, exhibiting high recyclability of the cross-linked POUUs.