Electromagnetic Interference Shielding Performance of CNT Sponge/PDMS Force-Sensitive Composites

In order to obtain a force-sensitive composite structure with high-performance electromagnetic interference (EMI) shielding, this paper proposes a method for preparing flexible force-sensitive composites by backfilling PDMS into a carbon nanotube (CNT) sponge using a vacuum-assisted method. Compared with CNTs/PDMS force-sensitive composites with different content prepared by the traditional solution blending method, the CNT sponge/PDMS force-sensitive composite prepared by the vacuum-impregnation method demonstrated sensitivity of 70 in a strain range of 35–50% at a thickness of 1 mm with a low filler content of 1 wt.%, and also showed excellent cyclic stability. The EMI shielding effectiveness (SE) reached 34.56 dB in the X band, and it still maintained high EMI SE (33.68 dB) after 500 repeated stretching cycles, which would be sufficient for commercial applications. The prepared CNT sponge/PDMS force-sensitive composite not only meets the basic sensitivity at low content (only 1 wt.%) but also has high EMI SE (34.56 dB) due to its high electrical conductivity (53 S/m), which makes it have potential applications in flexible stress sensors.