Electromagnetic interference (EMI) shielding materials with favorable flexibility, robustness, and multipurpose capabilities are urgently desired for smart wearable devices. Herein, flexible PDMS/cellulose nanofiber/Ag nanowire composite films with sandwich structures were successfully fabricated by a facile method. First, silver nanowires (AgNWs) were uniformly stacked in the upper part of the cellulose gel using a controlled two-step vacuum-assisted filtration; next, AgNWs were tightly embedded in the cellulose matrix by a hot-pressing strategy; finally, a hydrophobic protective layer, PDMS, was introduced. The water contact angle (WCA) of composite films could reach 121°. Compared with uniformly mixed films, AgNWs deposited only on the surface of the matrix allowed the conductivity to reach 381 S/cm at a low weight fraction of AgNWs (6 wt%). Thanks to such excellent conductivity, the composite films exhibited superior EMI shielding effectiveness (49 dB) at only 40 μm thickness, and Joule heating performance, i.e., the surface temperature reached 111.3 °C at 1.5 V driving voltage. It was worth noting that after bending and peeling damage, the WCA and EMI shielding effectiveness of composite films were not significantly impacted due to the hot-pressing strategy and hydrophobic surface protection. The robust composite films show huge application potential in the wearable electronics field.

中文翻译：

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柔性、疏水且坚固的复合薄膜，具有三明治结构，用于电磁干扰屏蔽和焦耳加热

智能可穿戴设备迫切需要具有良好灵活性、坚固性和多用途功能的电磁干扰（EMI）屏蔽材料。在此，通过简便的方法成功制备了具有三明治结构的柔性PDMS/纤维素纳米纤维/Ag纳米线复合薄膜。首先，使用受控两步真空辅助过滤将银纳米线（AgNW）均匀堆叠在纤维素凝胶的上部；接下来，通过热压策略将银纳米线紧密嵌入纤维素基质中；最后，引入了疏水性保护层PDMS。复合膜的水接触角(WCA)可达121°。与均匀混合的薄膜相比，仅沉积在基体表面的AgNWs可以在较低的AgNWs重量分数（6wt%）下使电导率达到381S/cm。得益于如此优异的导电性，复合薄膜在仅40μm的厚度下就表现出优异的EMI屏蔽效能（49dB）和焦耳热性能，即在1.5V驱动电压下表面温度达到111.3℃。值得注意的是，在弯曲和剥离损坏后，由于热压策略和疏水表面保护，复合薄膜的WCA和EMI屏蔽效能并未受到显着影响。坚固的复合薄膜在可穿戴电子领域显示出巨大的应用潜力。