Thermoresistive Network in Phase‐Transition Hydrogel: Achieving on/off Switchable Electromagnetic Interference Shielding

Abstract Intelligent electromagnetic interference (EMI) shielding materials, with their tunable EM wave response characteristics, have attracted much attention. However, the molecular‐level response mechanism is under‐explored and the tuning range is narrow. This study proposes an EMI shielding switch hydrogel based on molecular precision manipulation of a thermoresistive network capable of adaptively regulating electromagnetic shielding performance. It has two temperature‐controlled switching states: on/off and strong/weak shielding. The hydrogel consists of interpenetrating polyvinyl alcohol (PVA) and poly(N‐isopropylacrylamide) (PNIPAM) networks, giving it thermal shrinkable properties. A temperature‐induced high contact resistance MXene‐carbon nanotubes (MXene‐CNTs) conductive network is assembled within it. This combination enables the hydrogel to have switchable EMI shielding performance in the X‐band, with a range of 9.3–53.9 dB at different temperatures or thicknesses. The remarkable performance results from the synergistic effect of a temperature‐driven shrinkage matrix and a thermoresistive network, involving adjustments of conductive particle stacking, hydrogel conductivity, and electromagnetic wave transmission path. MXenes offer remote‐controlled photothermal‐responsive on/off switchable EMI shielding. Significantly, the hydrogel's self‐healing properties allow it to endure damage and its EMI shielding performance can be quickly restored. This work paves a new way for the rational design of adaptive EMI shielding devices at the molecular level.