Electromagnetic interference (EMI) shielding rubber composites with thermally insulating properties are necessary for some specific sealing fields, but their fabrication is challenging because it is difficult to realize a balance between high electrical conductivity and low thermal conductivity. Herein, symmetric sandwich–like rubber composites composed of an unfoamed core sandwiched by two foamed layers were prepared using a layer-by-layer vulcanization procedure. Importantly, a segregated Fe3O4@carbon nanotube (Fe3O4@CNT) network was constructed within the entire composite. This structure improved the shielding effectiveness (SE) and decreased the thermal conductivity of Fe3O4@CNT/rubber composites. When the density of the foamed layers was 0.60 g/cm3, the thermal conductivity, electrical conductivity, and SE of the resultant composites were 0.14 W/m K, 21.5 S/m, and 40.7 dB, respectively, and their green index (gs) was 2.13, implying that the prepared materials were “green” EMI-shielding composites. This study provides directions on fabricating EMI shielding materials with thermally insulating performance.
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