Construction of Ultrathin Self-Healing Films with Joule Heating Capability by Mxene Encapsulating Liquid Metal for Highly Efficient Electromagnetic Interference Shielding

Improving the compatibility of liquid metal (LM) in polymers to develop multifunctional LM-based flexible films for electromagnetic interference (EMI) shielding remains a challenge. In this work, LM nanoparticles encapsulated by MXene nanosheets are introduced into the waterborne polyurethane (WPU) matrix to construct the LM@MXene/WPU (LMW) films. MXene nanosheets can form strong interactions with both LM and WPU to enhance the dispersion stability of LM, thus avoiding phase separation. The ultrathin LMW films exhibit a high electrical conductivity of 374 S/cm, resulting in an average EMI shielding effectiveness (SE) exceeding 38.82 dB at a tiny thickness of only 5 μm in the frequency range of 8.2–12.4 GHz. Moreover, the resulting LMW films with outstanding Joule heat capability can raise their surface temperature to above 135 ℃ under a constant voltage of 5 V within 10 s, which can activate the hydrogen bonds between LM@MXene and WPU chain to achieve a gratifying self-healing performance. In addition, the excellent EMI shielding stability of the LMW films is verified, providing a guarantee for their practical application. Therefore, this work provides a strategy of MXene encapsulating LM to develop ultrathin self-healing LM-based EMI shielding films with Joule heating capability for next-generation electronics.