Multifunctional tubular carbon nanofibers/polyurethane electromagnetic wave absorber with room-temperature self-healing and recyclable performance

Incorporating self-healing and recyclable capabilities into microwave absorbing materials is expected to facilitate the life extension, cost reduction, and performance stability, thereby meeting the practical applications. In this research, a recycling and room-temperature self-healing electromagnetic wave (EMW) absorber is designed, in which linear polyurethane cross-linked by aromatic disulfide bonds is used as healable matrix, and tubular carbon nanofibers (TCNFs) are employed to attenuate microwave. The resultant composites with a TCNFs content of 7 wt.% harvest a minimum reflection loss (RLmin) of −39.0 dB and an effective absorption bandwidth (EAB) of 2.9 GHz at a matching thickness of 4.0 mm. Driven by the reversible dynamic bonds including hydrogen bonds and aromatic disulfide bonds, the high healing efficiency of 88.7% at 25 °C and 93.2% at 60 °C is presented. Impressively, even after three repairing cycles at room temperature, a healable efficiency of 86.4% is acquired, and RLmin can still reach −39.1 dB at the same thickness, together with an EAB of 3.0 GHz. Additionally, the results of solvent recycling experiment manifest that the recycled specimen achieves the almost similar mechanical and microwave dissipation properties as original one. These attractive characteristics make the designed self-healing and recyclable composites promising for next-generation EMW consumption devices.