Synthesis of Diels–Alder bond and hydrogen bond synergistic shape memory self-healing polyurethane elastomers

Self-healing materials exhibit the ability to repair damage and restore their function. Shape memory assisted self-healing (SMASH) materials are smart materials that automatically close localized microscopic cracks and repair these cracks by bonding damaged surfaces. A novel temperature-responsive SMASH polymer composite was established by introducing Diels–Alder bonds (D–A) in polyurethane. In this article, dynamic D–A produced by the polymerization of furfurylamine and 4,4’-bismaleimidodiphenylmethane was introduced into the molecular chain to enable the polyurethane elastomers containing D–A bonds to acquire self-repairing capability. The self-healing properties of the synthesized material were examined using polarized light microscopy, which revealed excellent fracture healing. The mechanical properties before and after healing were tested, in which the initial maximum tensile strength of the material could reach 7.9 MPa, and the maximum tensile strength after self-healing was 7.3 MPa, with a repair rate of 91.8%; the maximum elongation was 585.9%, and the maximum elongation after self-healing was 469.5%, with a repair rate of 80.1%. In addition, this material has excellent repair performance for microcracks of different scales, and the micromolten part of the surface after heating can fill the micrometer cracks, play the role of antiaging, and extend the service life of the material.