Cross-Linked Polyurethane/Bimetallic MOF-Derived Composites with Electromagnetic Wave-Absorbing, Self-Healing, and Recyclable Capabilities

The design and fabrication of electromagnetic wave (EMW) absorption materials with great wave-absorbing performance and excellent self-healing properties was significant. However, research on the interface effect, the three-dimensional conductive interconnection network, and the synergistic effect between EMW absorption performance and self-healing properties remained challenging. Herein, the synthetic strategy of in situ growth and multidynamic to cross-linking was raised to synthesize the polyurethane (PU)/bimetallic metal–organic framework (MOF)-derived composites (Pxy-CoNiNC@rGox%). The bimetallic MOF-derived moiety was constructed by multiple heterogeneous interfaces/porous structures/N-doped carbon nanotubes (NCNTs)/reduced graphene oxide (rGo), which synergistically improved the electromagnetic balance, multiple losses, and scattering, resulting in the excellent EMW absorption performance. As a result, the P33-CoNiNC@rGO14% composite showed satisfying EMW absorption properties with the minimum reflection loss (RLmin) of −55.65 dB at 9.05 GHz, and the effective absorption bandwidth (EAB10) of 4.22 GHz at 1.8 mm thickness. N-doped nanoparticles formed interfacial hydrogen bond interactions with polyurethane to construct a functional nanofiller-flexible polymer interface, which ultimately improved the compatibility. P33-CoNiNC@rGO14% exhibited a high tensile strength (16.30 MPa) and fracture strain (123.51%). Simultaneously, the high reversibility of boroxines and hydrogen bonds endowed P33-CoNiNC@rGO14% with efficient healing at 85 °C and recycling at 30 °C in ethanol or ethanol/DMF mixture, while the composites could be restored to their original mechanical strength essentially after recycling. Our strategy provided a thread for the synthesis of EMW absorption composites with self-healing performance.