Multifunctional Hydrogels with Broadband Electromagnetic Interference Shielding and Infrared Stealth Performance in Harsh Environments with Low Conductive Filler Content

Stretchable conductive hydrogel composites with infrared stealth and electromagnetic interference (EMI) shielding are in high demand for aerospace, military, and soft robotics. However, realizing stable and efficient performance with low conductive filler content under harsh conditions remains a substantial challenge. Herein, a flexible multifunctional double network hydrogels with high performance and environmental stability was constructed via transition metal carbide/nitride (MXene)/(NH₄)₂SO₄-treated strategy-assisted ultrasonic dispersion and thermal polymerization method. The synergistic effect of MXene and (NH₄)₂SO₄ within the hydrogel system led to a 3-fold enhancement in mechanical properties, 20-dB improvement in EMI shielding effectiveness, and 40% enhancement in the gauge factor with only 0.12 wt % conductive filler. Benefiting from its high conductivity, efficient thermal insulation, and composite network structure, the double network hydrogels maintain stable EMI shielding and infrared stealth performance under various harsh conditions including repeated stretching, prolonged water evaporation, low-temperature freezing, high-temperature heating, alcohol lamp flame exposure, and high-strain stretching. These findings demonstrate that the hydrogels combine ultra-low filler efficiency, environmental robustness, and multifunctional adaptability, making it a promising candidate for next-generation aerospace, military, and wearable electronic applications.