Multi-functional graphene aerogels/epoxy resin composites with Janus structure for enhanced electromagnetic interference shielding

The creation of an ordered, dense structure and multiple interfaces holds immense importance in the design of graphene aerogel (GA)-based polymer electromagnetic interference (EMI) shielding materials. However, achieving simultaneous control over these structures during the preparation of GAs remains a formidable challenge. To address this, the compress-annealing assembly method was employed to fabricate aerogels with Janus structure (Z_xM_yGAs), which one surface is endowed with superior conductivity and the other with enhanced magnetism. Additionally, the structure of Z_xM_yGAs became densified and well-ordered perpendicular to the compression direction. Z_xM_yGAs showed excellent mechanical properties with a compressive strength of 3.12 MPa and a specific stress of 78.9 kPa·cm³/mg. When employed as a filler in epoxy resin, Z_xM_yGAs improved the conductivity, thermal conductivity, EMI shielding capabilities, and photothermal conversion efficiency of resulting composites (Z_xM_yGAs/EP). Notably, the conductivity and thermal conductivity of Z_xM_yGAs/EP composites were high to 168.2 S·m^-1 and 0.61 W·m^-1·K^-1. Furthermore, the unique electromagnetic wave loss mechanism of absorption-reflection-reabsorption induced by Janus structure has significantly improved the EMI shielding performance of Z_xM_yGAs/EP composite to 75.8 dB. The compress-annealing assembly method facilitates the properties regulation of aerogel, offering an ingenious approach for the design of functional electromagnetic shielding materials, which can cater to diverse applications.