Flexible\nConductive Polyimide Fiber/MXene Composite\nFilm for Electromagnetic Interference Shielding and Joule Heating\nwith Excellent Harsh Environment Tolerance

The development of flexible MXene-based\nmultifunctional composites\nis becoming a hot research area to achieve the application of conductive\nMXene in wearable electric instruments. Herein, a flexible conductive\npolyimide fiber (PIF)/MXene composite film with densely stacked “rebar-brick-cement”\nlamellar structure is fabricated using the simple vacuum filtration\nplus thermal imidization technique. A water-soluble polyimide precursor,\npoly­(amic acid), is applied to act as a binder and dispersant to ensure\nthe homogeneous dispersion of MXene and its good interfacial adhesion\nwith PIF after thermal imidization, resulting in excellent mechanical\nrobustness and high conductivity (3787.9 S/m). Owing to the reflection\non the surface, absorption through conduction loss and interfacial/dipolar\npolarization loss inside the material, and the lamellar structure\nthat is beneficial for multiple reflection and scattering between\nadjacent layers, the resultant PIF/MXene composite film exhibits a\nhigh electromagnetic interference (EMI) shielding effectiveness of\n49.9 dB in the frequency range of 8.2–12.4 GHz. More importantly,\nits EMI shielding capacity can be well maintained in various harsh\nenvironments (e.g., extreme high/low temperature, acid/salt solution,\nand long-term cyclic bending), showing excellent stability and durability.\nFurthermore, it also presents fast, stable, and long-term durable\nJoule heating performances based on its stable and excellent conductivity,\ndemonstrating good thermal deicing effects under actual conditions.\nTherefore, we believe that the flexible conductive PIF/MXene composite\nfilm with excellent conductivity and harsh environment tolerance possesses\npromising potential for electromagnetic wave protection and personal\nthermal management.