Directional Electromagnetic Interference Shielding Based on Step-Wise Asymmetric Conductive Networks

Bai Xue; Yi Li; Ziling Cheng; Shengdu Yang; Lan Xie; Shuhao Qin; Qiang Zheng

doi:10.1007/s40820-021-00743-y

Directional Electromagnetic Interference Shielding Based on Step-Wise Asymmetric Conductive Networks

Nanomicro Lett. 2021 Dec 6;14(1):16. doi: 10.1007/s40820-021-00743-y.

Authors

Bai Xue^{1

2}, Yi Li¹, Ziling Cheng¹, Shengdu Yang¹, Lan Xie^{3

4}, Shuhao Qin², Qiang Zheng^{5

6

7}

Affiliations

¹ Department of Polymer Materials and Engineering, College of Materials and Metallurgy, Guizhou University, Guiyang, 550025, People's Republic of China.
² National Engineering Research Center for Compounding and Modification of Polymer Materials, National and Local Joint Engineering Research Center for Functional Polymer Membrane Materials and Membrane Processes, Guiyang, 550014, People's Republic of China.
³ Department of Polymer Materials and Engineering, College of Materials and Metallurgy, Guizhou University, Guiyang, 550025, People's Republic of China. mm.lanxie@gzu.edu.cn.
⁴ National Engineering Research Center for Compounding and Modification of Polymer Materials, National and Local Joint Engineering Research Center for Functional Polymer Membrane Materials and Membrane Processes, Guiyang, 550014, People's Republic of China. mm.lanxie@gzu.edu.cn.
⁵ Department of Polymer Materials and Engineering, College of Materials and Metallurgy, Guizhou University, Guiyang, 550025, People's Republic of China. zhengqiang@zju.edu.cn.
⁶ College of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, People's Republic of China. zhengqiang@zju.edu.cn.
⁷ College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, People's Republic of China. zhengqiang@zju.edu.cn.

Abstract

Some precision electronics such as signal transmitters need to not only emit effective signal but also be protected from the external electromagnetic (EM) waves. Thus, directional electromagnetic interference (EMI) shielding materials (i.e., when the EM wave is incident from different sides of the sample, the EMI shielding effectiveness (SE) is rather different) are strongly required; unfortunately, no comprehensive literature report is available on this research field. Herein, Ni-coated melamine foams (Ni@MF) were obtained by a facile electroless plating process, and multiwalled carbon nanotube (CNT) papers were prepared via a simple vacuum-assisted self-assembly approach. Then, step-wise asymmetric poly(butylene adipate-co-terephthalate) (PBAT) composites consisting of loose Ni@MF layer and compact CNT layer were successfully fabricated via a facile solution encapsulation approach. The step-wise asymmetric structures and electrical conductivity endow the Ni@MF/CNT/PBAT composites with unprecedented directional EMI shielding performances. When the EM wave is incident from Ni@MF layer or CNT layer, Ni@MF-5/CNT-75/PBAT exhibits the total EMI SE (SE_T) of 38.3 and 29.5 dB, respectively, which illustrates the ΔSE_T of 8.8 dB. This work opens a new research window for directional EMI shielding composites with step-wise asymmetric structures, which has promising applications in portable electronics and next-generation communication technologies.

Keywords: Directional electromagnetic interference shielding; Electrical conductivity; Solution encapsulation; Step-wise asymmetry; Vacuum-assisted self-assembly.