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, (Ti3C2Tx 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 Ti3C2Tx/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 Ti3C2Tx and BNNS is 1:1 and the total mass fraction is 70 wt.%, the electrical conductivity (σ) of the Ti3C2Tx/CNF side of ITBCF reaches 166.7 S/cm, while the surface resistivity of the BNNS-OH/CNF side is as high as 304 MΩ. 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 (λ) 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 °C and the maximum steady state voltage reaches up to 58.2 mV.

中文翻译：

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具有 Janus 结构的多功能离子键合强化 （Ti3C2Tx MXene/CNF）-（BNNS/CNF） 复合薄膜，可实现出色的电磁干扰屏蔽和热管理


柔性多功能聚合物基电磁干扰 （EMI） 屏蔽复合薄膜在 5 G 通信技术、智能可穿戴设备、汽车电子和航空航天领域发挥着举足轻重的作用。本工作通过对 BNNS-OH/CNF 和 Ti3C2Tx/CNF 悬浮液的真空辅助过滤，制备了具有 Janus 结构的 （Ti3C2Tx MXene/cellulose nanofibers， CNF）-（羟基官能化 BNNS-OH）/CNF） 复合膜 （TBCF）。然后，通过 Ca2+ 离子渗透和冷压技术获得离子键合强化 TBCF （ITBCF）。Janus 结构赋予 ITBCF 独特的“一侧导电，另一侧绝缘”的特性。当 Ti3C2Tx 和 BNNS 的质量比为 1：1 且总质量分数为 70 wt.% 时，ITBCF 的 Ti3C2Tx/CNF 侧的电导率 （σ） 达到 166.7 S/cm，而 BNNS-OH/CNF 侧的表面电阻率高达 304 MΩ。Ca2+ 离子浸润后，ITBCF 的机械性能显著增强。ITBCF 的拉伸强度和模量分别为 73.5 MPa 和 15.6 GPa，与 TBCF 相比分别提高了 75.9% 和 46.2%。此外，ITBCF 表现出 57 dB 的出色 EMI 屏蔽效能 （SE） 和 9.49 W/（m K） 的导热系数 （λ）。此外，ITBCF 还表现出优异的光热和光电能转换性能。在功率密度为 120 mW/cm2 的模拟太阳照射下，表面稳定温度高达 65.3 °C，最大稳态电压高达 58.2 mV。