Robust, Flexible, and Superhydrophobic Fabrics for High-efficiency and Ultrawide-Band Microwave Absorption

Microwave absorption (MA) materials are essential for protecting against harmful electromagnetic radiation. In this study, highly efficient and ultrawide-band microwave-absorbing fabrics with superhydrophobic surface features were developed using a facile dip-coating method involving in situ graphene oxide (GO) reduction, deposition of TiO2 nanoparticles, and subsequent coating of a mixture of polydimethylsiloxane (PDMS) and octadecylamine (ODA) on polyester fabrics. Owing to the presence of hierarchically structured surfaces and low-surface-energy materials, the resultant reduced graphene oxide (rGO)/TiO2-ODA/PDMS-coated fabrics demonstrate superhydrophobicity with a water contact angle of 159° and sliding angle of 5°. Under the synergistic effects of conduction loss, interface polarization loss, and surface roughness topography, the optimized fabrics show excellent microwave absorbing performances with a minimum reflection loss (RLmin) of −47.4 dB and a maximum effective absorption bandwidth (EABmax) of 7.7 GHz at a small rGO loading of 6.9 wt%. In addition, the rGO/TiO2-ODA/PDMS coating was robust, and the coated fabrics could withstand repeated washing, soiling, long-term ultraviolet irradiation, and chemical attacks without losing their superhydrophobicity and MA properties. Moreover, the coating imparts self-healing properties to the fabrics. This study provides a promising and effective route for the development of robust and flexible materials with microwave-absorbing properties.