Electrically electromagnetic interference shielding microcellular composite foams with 3D hierarchical graphene-carbon nanotube hybrids

Three kinds of carbon-based fillers (thermally reduced graphene oxide-carbon nanotubes (TG-CN), chemically reduced graphene oxide-carbon nanotubes (RG-CN), graphene nanoplates-carbon nanotubes (GN-CN)) were synthesized. Their corresponding foams were fabricated by combined process of compression-molding and batch-foaming. While GN-CN/PMMA composite foams presented the bimodal microcellular structure, composite foams with RG-CN and TG-CN hybrids still shown typical unimodal cell-size distribution. Much higher electrical conductivity and electromagnetic interference shielding efficiency (EMI SE) were achieved in the TG-CN/PMMA foams, which is closely associated with high intrinsic electrical conductivity and thin hierarchical structure of TG-CN hybrids. Specifically, a prominent electrical conductivity of 2.92 S/m and an absorption-dominated EMI-SE of more than 30 dB in the X-band were achieved in the lightweight TG-CN/PMMA foams (~0.65 g/cm3) at 10 wt% loading. These results demonstrate the TG-CN hybrids are highly promising nanofillers which could endow the composite foams with superior conductive and mechanical performance towards outstanding EMI-shielding application.