Tunable electromagnetic interference shielding effectiveness via multilayer assembly of regenerated cellulose as a supporting substrate and carbon nanotubes/polymer as a functional layer
Tunable electromagnetic interference shielding effectiveness via multilayer assembly of regenerated cellulose as a supporting substrate and carbon nanotubes/polymer as a functional layer
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通过再生纤维素作为支撑基底和碳纳米管/聚合物作为功能层的多层组装可调节电磁干扰屏蔽效果
DOI：
10.1039/c6tc05516h
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发表时间：
2017
影响因子：
6.4
通讯作者：
Zhong-Ming Li
中科院分区：
文献类型：
--
作者：
Liang-Qing Zhang;Biao Yang;Jian Teng;Jun Lei;Ding-Xiang Yan;Gan-Ji Zhong;Zhong-Ming Li
将碳纳米管（CNTs）与纤维素相结合的混合系统显示出几个关键特性，可以满足新兴的多功能需求，例如良好的导电性和电磁干扰（EMI）屏蔽。因此，本文开发了一种微妙的方法来制备碳纳米管/纤维素复合膜，其特征是由聚环氧乙烷(PEO)/碳纳米管层作为EMI屏蔽层和再生纤维素层作为支撑基底组成的层状结构。由于PEO与纤维素链具有良好的相容性，因此它是CNTs与纤维素层之间界面粘附的强大增强剂，可有效防止材料的机械性能恶化；此外，高含量的CNTs和微量的PEO表现出极高的电导率，达到20 S cm−1。该层状结构薄膜具有20 S cm−1的极高导电性和35 dB以上的x波段EMI屏蔽效能，同时具有较高的抗拉强度和杨氏模量，分别为26.9和2615.4 MPa。此外，该复合材料显示出极高的比SE（高达1372.4 dB cm2 g−1），这是CNT/纤维素材料前所未有的结果。相比之下，通过普通直接混合工艺制备的普通结构复合材料的电导率要低得多，为2 S cm−1，EMI屏蔽性能较差，为20 dB。此外，普通结构复合材料的机械强度和杨氏模量严重下降（分别为12.4和1274.3 MPa）。薄膜厚度和导电层数对电磁干扰屏蔽性能有显著影响，表明该复合材料具有可调的电磁干扰SE。具体来说，总厚度的增加会导致超过65 dB的超高SE。虽然它们的总厚度与单层膜相同，但多层膜的EMI SE明显增强，这是由导电层和纤维素层内部界面的相干多次反射驱动的。该研究可能为开发具有可调电磁干扰屏蔽效能的纤维素基复合薄膜提供更广泛的背景；这些薄膜可用于便携式电子设备和辐射源。
Hybrid systems integrating carbon nanotubes (CNTs) with cellulose showcase several key properties that can address emerging multifunctional needs, such as good electrical conductivity and electromagnetic interference (EMI) shielding. Herein, a subtle approach is accordingly developed to prepare CNTs/cellulose composite films that feature a layered structure consisting of a poly(ethylene oxide) (PEO)/CNTs layer as the EMI shielding layer and a regenerated cellulose layer as the supporting substrate. PEO acts as a robust enhancer of interfacial adhesion between the CNTs and the cellulose layers due to its favorable compatibility with cellulose chains, which is effective to prevent deterioration of the mechanical properties of the material; moreover, the high content of CNTs with trace amounts of PEO shows an extremely high electrical conductivity of 20 S cm−1. The layer-structured film shows an extremely high electrical conductivity of 20 S cm−1 and an excellent EMI shielding effectiveness (SE) of above 35 dB in the X-band, together with high tensile strength and a Young's modulus of 26.9 and 2615.4 MPa, respectively. Moreover, the composite shows extremely high specific SE (up to 1372.4 dB cm2 g−1) – an unprecedented result for CNT/cellulose materials. Comparatively, a plain-structured composite counterpart prepared via the normal direct-mixing process exhibits a much lower electrical conductivity of 2 S cm−1 and an inferior EMI shielding performance of 20 dB. Furthermore, the plain-structured composite suffers profound deterioration in mechanical strength and Young's modulus (12.4 and 1274.3 MPa, respectively). The film thickness and number of conducting layers significantly influence the EMI shielding performance, which indicates tunable EMI SE for this composite. Specifically, an increase in the total thickness leads to ultrahigh SE exceeding 65 dB. Although they have the same total thickness as monolayer films, a distinct enhancement in EMI SE for the multilayer films is clearly demonstrated, driven by the coherent multiple reflections at the internal interfaces of the conductive and cellulose layers. This study may provide a broader context for exploiting cellulose-based composite films with tunable electromagnetic interference shielding effectiveness; these films may find applications in portable electronic devices and radiation sources.