Enhanced electromagnetic wave absorption performance of hematite@carbon nanotubes/polyacrylamide hydrogel composites with good flexibility and biocompatibility

To expand the application field of electromagnetic wave functional materials based on light, thin, and cost-effective, the integration of the structure and function of electromagnetic wave materials is the key research goal. In this work, hematite(Fe₂O₃)@carbon nanotubes (CNTs)/polyacrylamide hydrogel composites with good flexibility and biocompatibility were prepared, and the hydrogel composite exhibited excellent electromagnetic wave (EMW) absorption performance, even with a low load ratio of Fe₂O₃@CNTs (2,4,6 wt.%) achieved—the minimum reflection loss (RL_min) value of 2 wt.% Fe₂O₃@CNTs/polyacrylamide (PAM) is − 60.96 dB at 15.87 GHz with a matching thickness is 1.63 mm and a wide effective absorption bandwidth (EAB) of about 3.4 GHz. Furthermore, the RL_min values of 4 wt.% Fe₂O₃@CNTs/PAM reach − 55.65 dB at 14.15 GHz. In addition, when the thickness of the hydrogel composite is between 1.56 and 1.64 mm, almost all electromagnetic waves can be absorbed in the Ku band frequency. Therefore, the impedance matching of the hydrogel composite was optimized, and EMW absorption performance was improved by introducing Fe₂O₃@CNTs. This work provides a strategy for designing a structure–function integrated EMW absorber and a convenient method for preparing flexible and biocompatible EMW hydrogels, which will be conducive to the wider application of EMW functional materials in daily life.

Graphical Abstract

Excellent absorption performance is achieved at a low load ratio of Fe₂O₃@CNTs (2 wt.%), successfully designing hydrogel absorbers with good flexibility and biocompatibility