Multi-walled carbon nanotube/polyethersulfone nanocomposites for enhanced electrical conductivity, dielectric properties and efficient electromagnetic interference shielding at low thickness

Herein, we report the synthesis of a high performance electromagnetic interference shielding (EMI) composite by utilizing polyethersulfone (PES) as a model matrix. Thin films of PES filled with conductive multi-walled carbon nanotubes (MWCNTs) were fabricated by a simple solution casting technique. The effect of filler concentration on EMI shielding efficiency, dielectric constant, electrical conductivity, hardness and thermal stability were investigated, and these properties were found to improve with the filler amount. An exceptionally high EMI shielding effectiveness of 35 dB (well above the common commercial EMI shielding requirement of 20 dB) was obtained in the X-band at a low thickness of 0.5 mm. Furthermore, the PES based CNT composites displayed a high electrical conductivity of 450 S/m. A high dielectric constant of 127 was obtained for a 20 wt% CNT filled polymer composite which was 40 times larger than the pure polymer matrix. Characterization tools indicate the intimate contact between the host matrix (PES) and CNT filler, which provided synergistic effects for improving dielectric properties as well as EMI shielding.