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Traditional epoxy resins are of technological significance for structural adhesives and composite materials, as well as many others. However, brittleness limits its further development, and achieving a combination of toughness and rigidity in epoxy networks remains a great challenge. In this work, we designed and synthesized low-temperature curable, tough and repairable epoxy networks via hindered urea bond (HUB) crosslinking strategies. Mechanical testing revealed that the material exhibited simultaneously improved toughness and stiffness, and specifically, tensile strength, elongation at break, and toughness were able to reach 78.2 MPa, 8.61%, and 4.63 MJ · m−3, respectively. More importantly, the dynamic exchange of HUB dispersed between polymer chains enables HUB crosslinked epoxy with thermal-triggered reparability and recyclability. In addition, thermal properties, chemical stability and water resistance of toughened epoxy samples were also characterized. This work provides a practical guidance for the exploration of high-performance epoxy with the potential to be extended to other polymers. [ABSTRACT FROM AUTHOR]

Intrinsic self-healing waterborne polyurethane (WPU) is an environmentally friendly, economically viable, and practical novel intelligent material. However, the key to achieving practical applications lies in the remote activation of repair in self-healing materials and the excellent mechanical properties of the matrix. In this study, we introduce quadruple hydrogen bonding in the polyurethane backbone. We have incorporated a novel two-dimensional sheet-like material, MXene, to achieve visible light remote-driven self-healing of material hydrogen bonds while enhancing the material’s mechanical properties. By utilizing the MXene supernatant, this approach not only resolves the issues of poor stability and easy sedimentation of MXene nanosheets in water-based polymers but also helps to prevent resource wastage. Our research results demonstrate that the composite film exhibits a tensile strength of 6.55 MPa and a fracture elongation of 604%. Additionally, quadruple hydrogen bonds in the WPU chains enable rapid self-healing of microcracks under visible light irradiation at 300 mW/cm2, with complete disappearance within 80 min. [ABSTRACT FROM AUTHOR]