Janus-structured ion-bridged MXene@PDA@PNF flexible composite films for synergistic infrared stealth, Joule thermal management, and EMI shielding

With the rapid advancement of wearable electronics and the growing demand for integrated infrared stealth, electromagnetic protection, and intelligent thermal management in modern civilian and military applications, lightweight, ultrathin, flexible, and high-performance multifunctional composite materials have become a research focus. This study employs a Janus heterogeneous interface strategy to construct a spatially functional Ca²⁺-MXene@PDA@PNF composite film (CMDP) through the synergistic effects of biomimetic polydopamine-mediated non-covalent modification of the PNF substrate and Ca²⁺ bridging densification of MXene. With just 11 wt.% MXene and a thickness of 26 μm, the film achieves low infrared emissivity (ε = 0.128, 8–14 μm), high in-plane thermal conductivity (14.406 W m⁻¹ K⁻¹), and reduces the infrared radiation temperature of a 300°C target by 205.2°C. It exhibits rapid thermal response (t < 10 s) and wide temperature control (27.6–352.6°C) under 0.5–5 V, enabling self-adaptive dynamic infrared stealth. The film also provides excellent electromagnetic shielding (14512 dB cm² g⁻¹, X-band) and outstanding mechanical properties, including tensile strength (184.2 MPa), elongation at break (28.7%), and thermal stability (T_d,5% = 558.1°C). These features position CMDP as a promising material for wearable infrared stealth, electromagnetic shielding, and thermal management applications.