Electromagnetic interference shielding property of silver nanowires/polymer foams with low thermal conductivity

Lightweight porous materials have attracted burgeoning interest in recent research on highly effective electromagnetic interference (EMI) shielding materials owing to their tunable density and low thermal conductivity. In this paper, acrylic copolymer (AC)/silver nanowire (AgNW) foams with segregated networks were synthesized by high-speed mechanical mixing followed by a hot-pressing method. As the AgNW volume content was increased from 0.12 vol% to 0.31 vol%, the electrical conductivity of the foams was increased from 0.89 S m⁻¹ to 142.99 S m⁻¹, which is attributed to the presence of a gradually perfect segregated AgNW network. A porous structure surrounded by AgNWs, as well as excellent electrical conductivity, endows the resultant foams with an outstanding EMI shielding effectiveness (SE) that reaches as high as 63 dB and an excellent specific SE (defined by the SE to density ratio) of 180 dB cm³ g⁻¹ in the X-band (8.2 GHz ~ 12.4 GHz). Moreover, the obtained AC/AgNW foams exhibit low and tuneable thermal conductivity, which can be varied from 0.022 W m⁻¹ K⁻¹ to 0.147 W m⁻¹ K⁻¹ by controlling the foam density (0.07 g cm⁻³–0.35 g cm⁻³). Lightweight AC/AgNW foams with high EMI SE and low thermal conductivity can be potentially applied in the field of aerospace and wearable smart material.