Multifunctional composite foam with high strength and sound‐absorbing based on step assembly strategy for high performance electromagnetic shielding

Abstract Soft polyurethane (PU) materials exhibit excellent structural stability, sound absorption and heat insulation, and they can be used to prepare multifunctional conductive composites with electromagnetic interference (EMI) shielding function. On the basis of a multistep assembly strategy, our study constructed composite foams with sound absorption and EMI shielding properties by designing different functional layers and expanded the application field of PU foam. First, carbon black particles are compounded with PU foam to improve the mechanical properties and conductivity of pure foam. Then, an aluminum layer and a knitted fabric layer were introduced to construct composite foam samples with a sandwich structure, endowing the materials with excellent EMI shielding performance. The resultant composite foam material exhibits effective EMI shielding performance and good sound absorption performance, which are 58.33 dB and >0.3, respectively. Moreover, the composite foam material demonstrates high bursting strength and compression resistance, suggesting that it can be used under different conditions. The employment of the multistep assembly strategy provides PU foam with a flexible range of applications, offering an innovative approach for preparing multifunctional conductive composite materials.