As wireless devices, high-frequency electronics, and communication technologies become increasingly common, electromagnetic interference, or EMI, is becoming a growing concern for device reliability, signal quality, and information security. Conventional shielding materials often work mainly by reflecting electromagnetic waves, which can create unwanted secondary radiation. Researchers are therefore seeking lightweight materials that can absorb electromagnetic energy while remaining strong, flexible, and sustainable.
A research team has now developed a multifunctional composite that addresses these challenges by combining flash-Joule-heated bamboo-derived biochar with a carefully engineered layer-by-layer polymer structure. The material achieved an electromagnetic interference shielding effectiveness of 36.7 dB, with 84% of the shielding contribution coming from absorption rather than reflection. At the same time, its fracture toughness reached 2.68 MJ m⁻³, representing a 173% improvement compared with the conventional PLA/PBAT blend.
"Our goal was not simply to increase electromagnetic shielding, but to design a material that could absorb electromagnetic energy efficiently without sacrificing mechanical performance," said corresponding author Qingfa Zhang. "By combining flash Joule heating, surface modification, and a layered architecture, we were able to create conductive pathways while strengthening the interfaces between the polymer layers."
The researchers began with biochar produced from bamboo. The biochar was subjected to flash Joule heating, an ultrafast process that briefly raised its temperature to approximately 3,000 K, restructuring the carbon framework and improving its conductive properties. The treated biochar was then modified with APTES, a silane coupling agent designed to improve its compatibility with the surrounding polymer matrix.
Instead of simply mixing the conductive biochar throughout the polymer, the researchers placed it strategically between alternating layers of polylactic acid, or PLA, and polybutylene adipate-co-terephthalate, or PBAT. This layer-by-layer structure formed continuous conductive regions while also creating interfaces that could redirect cracks and redistribute mechanical stress.
The resulting composite showed substantial mechanical gains. Its tensile strength increased from 14.1 MPa to 25.5 MPa, an improvement of about 81%, while elongation at break more than doubled from 11.5% to 24.7%. Toughness increased from 0.98 to 2.68 MJ m⁻³. Microscopic observations showed that the layered structure helped deflect cracks along more complex paths, allowing the material to dissipate more energy before failure.
Electrical performance also improved dramatically. The optimized composite reached a conductivity of 12.8 S cm⁻¹ and an average EMI shielding effectiveness of 36.7 dB across the X-band frequency range. By comparison, a conventionally prepared composite containing the same amount of modified biochar achieved only 7.5 dB, highlighting the importance of the layered architecture.
The material also demonstrated stable Joule heating behavior, reaching about 58 °C at 9 V and maintaining consistent performance over repeated heating and cooling cycles. This multifunctionality could broaden its potential use in electromagnetic protection, smart electronics, thermal management, and other applications requiring lightweight conductive materials.
The study demonstrates that sustainable carbon materials can do more than replace conventional fillers. Through deliberate control of their structure and placement, they can help create multifunctional composites that combine electromagnetic protection with mechanical durability.
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Journal reference: Chen J, Ren J, Huang M, Yu C, Song S, et al. 2026. Sustainable carbon-based composites with integrated toughening and electromagnetic interference shielding performance enabled by Flash-Joule-heating. Sustainable Carbon Materials 2: e029 doi: 10.48130/scm-0026-0026
https://www.maxapress.com/article/doi/10.48130/scm-0026-0026
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About Sustainable Carbon Materials :
Sustainable Carbon Materials (e-ISSN 3070-3557) is a multidisciplinary platform for communicating advances in fundamental and applied research on carbon-based materials. It is dedicated to serving as an innovative, efficient and professional platform for researchers in the field of carbon materials around the world to deliver findings from this rapidly expanding field of science. It is a peer-reviewed, open-access journal that publishes review, original research, invited review, rapid report, perspective, commentary and correspondence papers.
