Lightweight microwire/graphene/silicone rubber composites for efficient electromagnetic interference shielding and low microwave reflectivity

Most traditional fillers used in electromagnetic shielding composites require high loading, uniform distribution and complicated structures for modest property enhancement. Here, we propose a simple shielding system incorporating magnetic microwires M and graphene fibers G in different arrangements. Integrating both fillers in the composite resulted in superior shielding effectiveness (SE) with respect to incorporating either individual type of filler, due to improved absorption efficiency, impedance matching and polarization triggered by different arrangements of the fillers. Randomly dispersed arrays provided a maximum shielding of 6 dB for equal amount of G and M, in which polarization effects at the interface between the two regions contributed to the SE value. The highest SE of 18 dB (98.4% attenuation) was reached by the MMMGGG periodic arrays with merely 0.059 wt% filler loading enabled by the optimized arrangement and wave attenuation from the microwires dielectric/magnetic response. The normalized SE of this composite was about two to four orders of magnitude higher than that of many other shielding candidate materials. High SE, low loading, simple structure, and multifunctionality make these composites attractive for several applications. Moreover, tailoring topological and structural factors of both fillers would facilitate further SE enhancement without sacrificing the important lightweight advantage.