Facile and green fabrication of segregated ABS/CNT foams with superior electrical conductivity and ultrahigh EMI shielding performance

Abstract

Conductive polymer composite (CPC) foams, which possess excellent electrical properties and unique structures, offer great advantages for practical applications in electromagnetic interference (EMI) shielding. Herein, acrylonitrile-butadiene-styrene (ABS)/carbon nanotube (CNT) composites and their foams with segregated conductive networks were fabricated by a novel method combining cold and hot compaction with supercritical CO₂ foaming. The segregated ABS/CNT composite with 8% CNT content exhibited ultrahigh electrical conductivity (EC) (1.75 S cm⁻¹), dielectric loss (3.93), and average EMI shielding effectiveness (EMI SE) (71.21 dB) at 8.2–12.4 GHz (X band). After foaming, the resultant foams also achieved satisfactory EC (0.52 S cm⁻¹), dielectric loss (2.42), and average EMI SE (55.93 dB) at the X band. Furthermore, the segregated ABS/CNT foam with 8% CNT content reached the highest absolute EMI SE of 419.26 (dB g⁻¹ cm²). The EMI shielding mechanism of the ABS/CNT composites and their foams with segregated structures were explored in detail. Except for pure ABS, the EMI shielding mechanism of the ABS/CNT composites was dominated by reflection, whereas that of the segregated ABS/CNT foams was absorption, which could effectively prevent electromagnetic wave pollution. This study offers a facile and environmentally friendly strategy to further strengthen the EC and EMI SE of CPC foams in the EMI shielding domain.