Lightweight Multifunctional Poly(dimethylsiloxane)/Hollow Microsphere/Carbon Nanotube Composite Foam for Electromagnetic Interference Shielding and Thermal Management

With the rapid development of 5G technology and intelligent systems, the demand for lightweight, multifunctional electromagnetic interference (EMI) shielding materials has surged. Herein, a compressible, durable, and conductive poly(dimethylsiloxane)/hollow microsphere/carbon nanotube (PDMS/HM/CNT) composite foam is fabricated via a template-assisted method. By optimization of the HM content, the composite foam achieves a density of 0.22 g/cm3 and an electrical conductivity of 1.38 S/m, along with an exceptional average EMI shielding effectiveness of 62.1 dB in the X band. The closed-cell structure and uniform dispersion of HM not only enhance mechanical resilience but also enable multifunctional applications. The foam demonstrates remarkable thermal management capabilities, including Joule heating and photothermal conversion, facilitating rapid deicing. Its ultralow thermal conductivity (0.05 W/m·K at 10 wt % HM) and infrared stealth performance further highlight its potential for thermal insulation and covert applications. Additionally, the foam exhibits excellent piezoresistive sensing behavior with high stability, enabling reliable human motion detection. This work provides a scalable strategy for designing multifunctional polymer composites, bridging the gap between high-performance EMI shielding and versatile applications in wearable electronics, aerospace, and energy systems.