Ultralight core–shell polypyrrole@bacterial cellulose aerogel for broadband electromagnetic wave absorption and efficient heat insulation

The rapid expansion of high-power electronics and wearable systems exposes them to complex electromagnetic and thermal stresses. External electromagnetic interference (EMI) and heat in the environment cause marked surface warming, a compound effect that accelerates material degradation and performance decline, thereby compromising long-term device reliability and safety. To address this dual challenge, this study developed an ultra-lightweight core–shell composite aerogel material. The material was synthesized by constructing a three-dimensional (3D) porous scaffold based on bacterial cellulose aerogel (BCA), followed by in-situ polymerization of polypyrrole (PPy) on its surface to form a homogeneous core–shell structure. The core-shell architecture serves as an effective strategy for optimizing conductive networks and enhancing dielectric loss mechanisms. This design results in a minimum reflection loss (RL min ) of −48.55 dB at 6.80 GHz, with an effective absorption bandwidth (EAB) of 6.64 GHz, covering the range from 9.68 to 16.32 GHz. Additionally, its highly porous structure forms continuous air barriers and thermal resistance paths, achieving thermal insulation with a temperature reduction of ~5.4 °C (verified by infrared thermography). This work proposes a synergistic design for dual-functional electromagnetic wave absorption (EWA)/thermal insulation materials, offering a scalable strategy for fabricating lightweight, high-performance protective materials.