Lightweight flexible polyurethane/reduced ultralarge graphene oxide composite foams for electromagnetic interference shielding

Abstract

Multifunctional flexible polyurethane (PU)/reduced ultralarge graphene oxide (rUL-GO) composite foams with low density in the range of ∼53–92 kg m⁻³ were fabricated through the in situ polymerization of PU in the presence of rUL-GO. The incorporation of 1 wt% rUL-GO gave the insular flexible PU composite foams a high electrical conductivity of 4.04 S m⁻¹, and an excellent electromagnetic interference (EMI) shielding efficiency of ∼253 dB (g⁻¹ cm⁻³) at 8–12 GHz. Achieving such a high specific EMI shielding efficiency as well as a low percolation threshold, combined with the method of foam preparation, results in a uniform dispersion and very high aspect ratio (>20 000) for the rUL-GO nanosheets. Furthermore, by the introduction of rUL-GO, the Young’s modulus and tensile strength of the PU composite foams also improved significantly without reducing the flexibility. TGA experiments also indicated the enhanced thermal stability of the composite foams.