The increasing congestion of electronic devices and the need for electromagnetic interference (EMI) shielding demand new materials that can perform multiple functions simultaneously. However, integrating EMI shielding, thermal management and infrared stealth into a single, high-performance material has remained a challenge.
In a study published in the KeAi journal Advanced Nanocomposites, researchers from Shenyang University of Chemical Technology in China developed a breakthrough multifunctional foam that successfully combines all these capabilities.
"Most studies focus on one function and restricted working mechanisms. We aimed to create a sustainable, integrated material that solves several problems at once," says co-corresponding author of the study Professor Hailan Kang. "By using a bio-based matrix and a smart synergistic design, we've developed a foam that not only protects against EMI but also manages heat effectively and remains covert to thermal imaging."
Inspired by nature crystalline rubber, the team used eucommia ulmoides gum (EUG), a natural rubber derived from trees, as the base material. The researchers employed a salt-template method to create a porous foam structure, into which they integrated two nanoscale conductive materials: carbon nanotubes (CNTs) and a two-dimensional material known as MXene.
"A key innovation is that the foam is a synergetic integration of multiple mechanisms," explains Kang. "The 2-millimeter-thick foam exhibits an exceptional shielding effectiveness of 49.7 dB in the X-band, meaning it blocks over 99.9989 % of electromagnetic waves."
Notably, its porous structure traps air, giving it excellent thermal insulation (0.15 W·m⁻¹·K⁻¹). Meanwhile, the MXene component and smooth surface give it a low infrared emissivity, making it harder to detect by thermal cameras.
"The foam's ability to act as a thermal buffer is a notable result," says Kang. "The natural EUG polymer undergoes a solid-solid phase change, absorbing and releasing large amounts of heat (36.8 J/g), which prevents heat buildup and helps regulate surface temperature."
The foam also proved to be remarkably robust, with a compressive strength 825% higher than the pure EUG foam, and maintained 83.5 % of its shielding performance after a rigorous 12-day durability test under high heat and humidity.
"This work provides a novel strategy for designing next-generation multifunctional EMI shielding materials," adds co-corresponding Genshi Liu. "We believe it can pave the way for applications in military equipment, aerospace and advanced electronics."
