Ultraflexible and Mechanically Strong Double-Layered Aramid Nanofiber-Ti3C2Tx MXene/Silver Nanowire Nanocomposite Papers for High-Performance Electromagnetic Interference Shielding.

High-performance electromagnetic interference (EMI) shielding materials with ultraflexibility, outstanding mechanical properties and superior EMI shielding performances are highly desirable for modern integrated electronic and telecommunication systems in areas such as aerospace, military, artificial intelligence, smart and wearable electronics. Herein, ultraflexible and mechanically strong aramid nanofiber-Ti3C2Tx MXene/Ag nanowire (ANF-MXene/AgNW) nanocomposite papers with double-layered structures are fabricated via the facile two-step vacuum assisted filtration (TVAF) followed by hot-pressing approach. The resultant double-layered nanocomposite papers with a low MXene/AgNW content of 20 wt% exhibit excellent electrical conductivity of 922.0 S·cm-1, outstanding mechanical properties with tensile strength of 235.9 MPa and fracture strain of 24.8%, superior EMI shielding effectiveness (EMI SE) of 48.1 dB and high EMI SE/t of 10688.9 dB·cm-1, benefiting from the highly efficient double-layered structures, high-performance ANF substrate and extensive hydrogen bonding interactions. Particularly, the nanocomposite papers show the maximum electrical conductivity of 3725.6 S·cm-1 and EMI shielding effectiveness (EMI SE) of ~80 dB at the MXene/AgNW content of 80 wt% with an absorption-dominant shielding mechanism owing to the massive ohmic losses in highly conductive MXene/AgNW layer, multiple internal reflections between Ti3C2Tx MXene nanosheets and polarization relaxation of localized defects and abundant terminal groups. Compared with the homogeneously-blended ones, the double-layered nanocomposite papers possess greater advantages in electrical, mechanical and EMI shielding performances. Moreover, the multifunctional double-layered nanocomposite papers exhibit excellent thermal management performances such as high Joule heating temperature at low supplied voltages, rapid response time, sufficient heating stability and reliability. The results indicate that the double-layered nanocomposite papers have excellent potential for high-performance EMI shielding and thermal management applications in aerospace, military and artificial intelligence, smart and wearable electronics.