Multifunctional ionic bonding-strengthened (Ti3 C2 Tx MXene/CNF)-(BNNS/CNF) composite films with Janus structure for outstanding electromagnetic interference shielding and thermal management

Flexible multifunctional polymer-based electromagnetic interference (EMI) shielding composite films play a pivotal role in 5 G communication technology, smart wearables, automotive electronics, and aerospace. In this work, (Ti3 C2 Tx MXene/cellulose nanofibers (CNF)-(hydroxy-functionalized BNNS (BNNS-OH)/CNF) composite films (TBCF) with Janus structure are prepared via vacuum-assisted filtration of BNNS-OH/CNF and Ti3 C2 Tx /CNF suspension by one after another. Then ionic bonding-strengthened TBCF (ITBCF) is obtained by Ca2 + ion infiltration and cold-pressing technique. The Janus structure endows ITBCF with the unique "conductive on one side and insulating on the other" property. When the mass ratio of Ti3 C2 Tx and BNNS is 1:1 and the total mass fraction is 70 wt.%, the electrical conductivity ( Q) of the Ti3 C2 Tx /CNF side of ITBCF reaches 166.7 S/cm, while the surface resistivity of the BNNS-OH/CNF side is as high as 304 M Q. After Ca2 + ion infiltration, the mechanical properties of ITBCF are significantly enhanced. The tensile strength and modulus of ITBCF are 73.5 MPa and 15.6 GPa, which are increased by 75.9% and 46.2% compared with those of TBCF, respectively. Moreover, ITBCF exhibits outstanding EMI shielding effectiveness (SE) of 57 dB and thermal conductivity ( 7) of 9.49 W/(m K). In addition, ITBCF also presents excellent photothermal and photoelectric energy conversion performance. Under simulated solar irradiation with a power density of 120 mW/cm2 , the surface stabilization temperature reaches up to 65.3 degrees C and the maximum steady state voltage reaches up to 58.2 mV. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.