To address the challenges posed by complex application scenarios, the development of microwave absorbing materials with hydrophobicity and flame retardancy has become a critical direction for next-generation communication technologies. In this study, poly(vinyl alcohol), a metal-polyphenol framework (Co2+-tannic acid), and aramid nanofibers (ANF) were self-assembled into the precursor aerogel through hydrogen and coordination bonds, where ANF enhanced the mechanical robustness. Then, after the carbonization process, porous C/Co aerogels were developed. The magnetic properties and graphitization degree of the C/Co aerogels were precisely tailored by modulating carbonization temperatures, enabling tunable microwave absorption performance. The C/Co aerogel carbonized at 800 °C achieved a minimum reflection loss (RLmin) of -65.2 dB at 2.48 mm thickness along with an effective absorption bandwidth of 4.48 GHz at 1.52 mm thickness. The optimized impedance matching, driven by synergistic magnetic-dielectric loss mechanisms, underpins its exceptional microwave absorption. Furthermore, the C/Co aerogel exhibited remarkable compressive strength (593.1 kPa), hydrophobicity (a hydrophobic angle of 124°), and flame retardancy. This work provides a strategic framework for designing multifunctional high-efficiency microwave absorbers.
Cheng et al. (Fri,) studied this question.