Ultra-Light Reduced Graphene Oxide Based Aerogel/Foam Absorber of Microwave Radiation.

We present the polarization-dependent highly absorptive in Ka-band composition of conventional polyurethane foam filled with in situ synthesized aerogel coated by reduced graphene oxide (rGO). The rGO-based aerogel was in situ prepared into the open-cell polyurethane foam (PUF) skeleton through a bidirectional freeze-drying process. The aerogel is composed of the flat lamellas stacks, possessing the anisotropic structure and unique electromagnetic properties. Further improvement of the electromagnetic shielding ability was possible by the rGO coating introduction as a coupling layer between PUF and rGO-based aerogel. This enhances the overall conductivity of the resulting composites: 1.41 + 3.33 S/m vs. 0.9 + 2.45 S/m for PUF loaded with in situ synthesized aerogel without rGO coating.With this mechanically robust plane easy to process coating one could achieve -20 dB by power with the record light structure (0.0462 g/cm²). That could compete in view of the weight per cm² even with graphene-based absorbers comprising either dielectric matching elements or back metal reflectors, or both.