Polymer composites with 3D graphene architectures as high-performance EMI shielding materials: a review

Abstract

Secondary electromagnetic pollution generated due to the inevitable reflection in solid/thin film conducting polymer composites has been a major barrier in realizing high-performance absorption-dominated electromagnetic interference (EMI) shielding. In the past, prodigious efforts were made to minimize the reflection by tailoring the impedance characteristics between the air and the substrate. For instance, incorporation of a microcellular scaffold (3D structure) such as foam and aerogel in a polymer matrix have been extensively investigated to tailor the surface impedance matching and achieve enhanced absorption. To date, application of the 3D graphene microcellular scaffold alone or its hybrid with other magnetic, conductive, and dielectric materials has been continuously pursued to diminish reflectivity and increase absorption via the dielectric and interfacial relaxation loss mechanism. An aerogel and foam structure contains multiscale pores (micro and nano scale pores). Through the large number of solid/air interfaces created by such pores, it can efficiently tune the impedance matching. The solid/air interface renders surplus EM wave attenuation capabilities by increasing the EM wave trajectory path via internal scattering within the pores. The 3D graphene architectures-based polymer composites show hitherto EMI shielding efficiency improvement at significantly low mass density and percolation threshold. However, most of the existing studies on 3D graphene-based composites rely on trial-and-error methods without comprehensively investigating the effect of the geometrical and microstructures aspects on the EMI shielding performance. Furthermore, the state-of-art literature does not (re)present an analytical/theoretical model that can be employed to optimize parameters appropriate for designing the absorption-dominated shielding material with diminished reflection. This review is intended to cover the latest progress and innovation around 3D graphene nanostructure-based polymer composites as EMI shielding materials. The EMI shielding properties of the composites, including graphene aerogels, foam and hybrid aerogel/foam, with other dielectric and magnetic materials are discussed along with the underlying mechanism. In addition, this review represents an input impedance model that can be utilized in conjunction with experimental design to optimize geometrical and microstructural parameters to realize an absorption-dominated shielding material. Based on the available status on 3D graphene scaffold-based composites, we summarize the current achievements and offer a route toward future developments.