Construction of Ti₃C₂T_x MXene Composite PI Nanogel Fiber With Excellent Infrared Stealth Performance

The rapid development of infrared detection technology has spurred extensive interest in advanced functional materials with exceptional infrared stealth capabilities. This work fabricates a novel thermal-insulation and radiation-modulation integrated infrared stealth material, integrating polyimide (PI) aerogel fibers (endowed with thermal insulation) and MXene/tannic acid (TA) composite (featuring low emissivity and oxidation resistance), to achieve thermal camouflage for high-temperature targets. In this composite system, the abundant pores within PI aerogel fibers not only suppress gas convective heat transfer but also extend the heat conduction path along the pore walls, thus achieving efficient thermal insulation. Meanwhile, MXene's metallic-like conductivity and layered structure enable it to efficiently reflect infrared thermal radiation, minimizing radiant heat loss to the surroundings. Consequently, the composite PI/SA/TM exhibits a low thermal conductivity of 0.084 W·m^-1·K^-1 and a low emissivity of 0.17. At an ambient temperature of 200 °C, its radiant temperature is merely 40.7 °C, outperforming pure PI, TM film and commercial fabrics in terms of stealth performance. The incorporation of TA further enhances oxidation stability for PI/SA/TM, retaining excellent emissivity (0.24) even after 15 days of humid heat aging. This work provides new technical support for designing advanced functional integrated infrared stealth materials.