Construction of ultrathin self-healing films with highly efficient electromagnetic interference shielding and Joule heating capability by MXene decorating liquid metal

Improving the compatibility of liquid metal (LM) in polymers to develop self-healing LM-based flexible films with electromagnetic interference (EMI) shielding and Joule heating capability remains a considerable challenge. In this work, LM nanoparticles encapsulated by MXene are introduced into waterborne polyurethane (WPU) matrix to construct LM@MXene/WPU (LMW) films by the electrostatic attraction interaction and the casting method. MXene 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 extremely high SE/t value (77640 dB/cm). Moreover, the LMW composite 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 feasible strategy for developing ultrathin self-healing films with EMI shielding and Joule heating capability for next-generation electronics.