Graphene fibre film/polydimethylsiloxane nanocomposites for high-performance electromagnetic interference shielding

Exploration of high-performance electromagnetic interference (EMI) shielding materials has become a trend to address the increasing electromagnetic (EM) wave pollution environment. In this paper, oriented graphene fibre film (GFF)/polydimethylsiloxane (PDMS) nanocomposites with one-ply unidirectional, two-ply cross-ply, and two-ply unidirectional configurations were prepared using wet-spinning and hot-pressing techniques in a two-step process. Due to the anisotropic electrical performance of GFF, the one-ply laminate exhibits EMI shielding anisotropy that is affected by fibre orientation relative to the electric field component in EM waves. The maximum shielding difference at 8.8 GHz is up to 32.0 dB between the fibre orientation parallel to and perpendicular to the electric field component. In addition, we found that adding a layer of GFF is an intuitive method to enhance the shielding efficiency (SE) of GFF/PDMS nanocomposites by providing more interfaces to enhance absorption losses. An optimal EMI shielding performance of a two-ply unidirectional laminate is observed with an SE value of 50.6 dB, which shields 99.999% of EM waves. The shielding mechanisms are also discussed and clarified from the results of both experimental and theoretical analyses by adjusting the GFF structural parameters, such as the fibre orientation, areal density, number of plies and stacking sequence.