Multifunctional Flexible WPU Composite Aerogels with Sandwich Structure for Dual‐Sided Low‐Reflection Electromagnetic Interference Shielding

Abstract With the increasingly severe electromagnetic pollution, the demand for low‐reflection electromagnetic interference shielding (EMI) materials has become progressively urgent. Based on the layered design, the (MXene@CoFe 2 O 4 /waterborne polyurethane (WPU))‐(MXene/WPU)‐(MXene@CoFe 2 O 4 /WPU) composite aerogels with sandwich structure (SWCA) are prepared by layer freezing and freeze‐drying method, using WPU as the matrix and heterostructure MXene@CoFe 2 O 4 prepared by solvothermal reduction as electromagnetic filler. When the mass ratio of MXene to CoFe 2 O 4 is 1:6, MXene@CoFe 2 O 4 exhibits optimal impedance matching (with the value of |Z in /Z 0 | closer to 1). Due to the synergistic effect between the absorbing layer of MXene@CoFe 2 O 4 /WPU aerogels and the reflecting layer of MXene/WPU aerogels, SWCA assembled with 80 wt.% MXene/WPU aerogels and 40 wt.% MXene@CoFe 2 O 4 ‐3/WPU aerogels achieve high EMI shielding effectiveness (77 dB) and low reflection (0.14) in the X band. Besides, SWCA demonstrates dual‐sided low‐reflection EMI shielding performance, to the extent that in practical applications, they are no longer restricted to specific installation directions. Moreover, SWCA shows high compressive stress (maximum compressive stress of 264.0 kPa at 50% compressive strain), compressive resilience (88% resilience after 100 cycles of compression), excellent thermal insulation (thermal conductivity between 0.0843 and 0.0941 W (m·K) −1 ) and infrared camouflage performance. The multifunctional flexible EMI shielding aerogels with low reflection and high performance holds great promise for application prospect in next‐generation electronic devices.