Multifunctional Electromagnetic Responsive Porous Materials Synthesized by Freeze Casting: Principles, Progress, and Prospects

Freeze casting is a solidification technique utilized in the fabrication of porous materials. However, the freeze casting process is quite complex, and significant challenges remain in precisely controlling the pore size and shape of porous structures. This study aims to investigate the customization of multifunctional electromagnetic wave (EMW) absorbers with 3D porous structures via freeze casting. This review initially presents the fundamental principles underlying the freeze casting technique and examines the correlation between internal and external factors during the preparation process and porosity. The emerging trends in constructing novel and intricate macroscopic structures through freeze casting are subsequently outlined. Furthermore, this review focuses on the fabrication of composites with various porous microstructures through freeze casting of low‐dimensional building blocks, and their EMW response and multifunctional properties. By regulating the internal and external influencing mechanisms of freeze casting, porous EMW absorption materials exhibit outstanding advantages such as electromagnetic property manipulation, controllable structure, high porosity, high specific surface area, lightweight, and flexibility. These features broaden their applications in electromagnetic shielding, mechanical property, radar stealth, thermal insulation and fire prevention, flexible sensors, antifreeze ability, etc. In addition, we discuss the challenges and prospects of high‐performance EMW absorbers using freeze casting techniques.