Fabrication of electromagnetic wave absorption nanocomposite foam with adjustable conductive network by supercritical carbon dioxide foaming

Polymer nanocomposite foams with high electromagnetic interference (EMI) shielding performance have become the research hotspot to reduce electromagnetic wave pollution. Herein, we prepared polyethylene/poly (vinylidene fluoride)/carbon nanotubes/Fe₃O₄(PE/PVDF/Fe₃O₄/CNTs) nanocomposites and nanocomposite foams by following the simple melt blending and batch foaming procedures. The co-continuous structure system of PVDF/PE was achieved by altering the matrix ratio of PVDF/PE, while reaching a maximum average EMI shielding efficiency of ca. 28 dB for the nanocomposite with PVDF/PE ratio of 5:5. Furthermore, the largest specific EMI SE of as high as 275 dB‧cm²‧g⁻¹ was obtained for the nanocomposite foam with PVDF/PE ratio of 9: 1, in which the EMI shielding mechanism is mainly based on absorption, leading to a significantly reduction in the secondary EM wave pollution. Therefore, the preparation of porous polymer nanocomposite foams with excellent EM wave absorption performance served as a novel strategy to reduce secondary EM wave pollution that holds great potential for applications in both military and civilian fields.