Multifunctional Lightweight Segregated CNT-Reinforced EVA/LDPE Foams With Superior Piezoresistive Characteristic and EMI Shielding Performance

The rapid development of 5th generation communication and wearable electronic devices has increased the demand for lightweight and flexible materials with excellent electromagnetic interference (EMI) shielding performance and piezoresistive sensing characteristics. Herein, cold/hot pressing was combined with supercritical CO 2 foaming to prepare segregated carbon nanotube (CNT)/ethylene-vinyl acetate copolymer (EVA)/low-density polyethylene (LDPE) sheets and related foams, exhibiting superior sensitivity and EMI shielding effectiveness (SE). Benefiting from the segregated distribution of CNT, CNT/EVA/LDPE sheets exhibited excellent conductivity of 0.38 S cm −1 . The composite foam with 6 phr CNT achieved a maximum absolute EMI SE of 113 dB (g/cm 2 ) −1 in the X-band (8.2–12.4 GHz) while maintaining high sensitivity (GF = 4.4), perfectly balancing piezoresistive sensing and EMI shielding performance. Apart from pure EVA/LDPE, the mechanism for EMI shielding in CNT/EVA/LDPE sheets was primarily based on reflection, while that of segregated CNT/EVA/LDPE foam was chiefly ascribed to absorption. Moreover, the segregated CNT/EVA/LDPE foam could accurately detect human motion, further demonstrating their practical application potential. This study provides new insights into the development of lightweight, multifunctional materials for EMI shielding and advances next-generation functional materials for flexible electronics and wearable devices. Highlights A composite that integrates mechanical, conductive, EMI shielding and sensing. S/C6-F shows excellent conductivity (0.01 S cm −1 ) and SSE/t (113 dB cm 2 g −1 ). Its porous structure shifts EMI shielding from reflection to absorption. A high gauge factor of 4.4 enables S/C6-F to accurately detect human motion. S/C6-F achieves 7 MPa stress at 60% strain, indicating mechanical stability.