Abstract Polypyrrole (PPy) is an electrically conductive organic material perspective for application in the field of electromagnetic interference shielding (EMI). The presented fundamental study focuses on the shielding efficiency of three various morphologies of PPy (globules, nanotubes and microbarrels). Powdered samples in both protonated and deprotonated form were embedded at various concentrations (1, 3 and 5 % w/w) in a composite system with a transparent silicone matrix cured at temperatures 25 and 150 °C. The ability of PPy to reflect or absorb electromagnetic radiation in the C-band region covering the range from 5.85 to 8.2 GHz was evaluated. The relationship between the morphology of PPy, its DC and AC electrical conductivity, permittivity and shielding efficiency was studied. The PPy nanotubes with the DC conductivity of 60.8 S cm–1 exhibited shielding efficiency S21 = –13.27 dB at 5% w/w concentration in the composite, which corresponds to transparency of 21.7 % only. It was found that the magnitude of electrical conductivity together with the aspect ratio of PPy morphology determines the shielding efficiency whereas the type of morphology is responsible for absorption or reflection mechanism of EMI shielding. Hence, the appropriate adjustment of both the electrical conductivity and the morphology should be used in the future lightweight and flexible EMI shields with tunable shielding efficiency and mechanism of shielding.

中文翻译：

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聚吡咯纳米结构的电磁干扰屏蔽

摘要 聚吡咯（PPy）是一种用于电磁干扰屏蔽（EMI）领域的导电有机材料。所提出的基础研究侧重于三种不同形态的 PPy（球状、纳米管和微管）的屏蔽效率。质子化和去质子化形式的粉末样品以不同浓度（1%、3% 和 5% w/w）嵌入复合系统中，该复合系统具有在 25 和 150 °C 温度下固化的透明有机硅基质。评估了 PPy 在覆盖 5.85 至 8.2 GHz 范围的 C 波段区域中反射或吸收电磁辐射的能力。研究了PPy的形貌与其直流和交流电导率、介电常数和屏蔽效率之间的关系。直流电导率为60的PPy纳米管。8 S cm-1 在复合材料中 5% w/w 浓度下表现出屏蔽效率 S21 = –13.27 dB，仅对应于 21.7% 的透明度。发现电导率的大小和 PPy 形态的纵横比决定了屏蔽效率，而形态类型决定了 EMI 屏蔽的吸收或反射机制。因此，在未来具有可调屏蔽效率和屏蔽机制的轻量级和灵活的 EMI 屏蔽中，应适当调整电导率和形态。发现电导率的大小和 PPy 形态的纵横比决定了屏蔽效率，而形态类型决定了 EMI 屏蔽的吸收或反射机制。因此，在未来具有可调屏蔽效率和屏蔽机制的轻量级和灵活的 EMI 屏蔽中，应适当调整电导率和形态。发现电导率的大小和 PPy 形态的纵横比决定了屏蔽效率，而形态类型决定了 EMI 屏蔽的吸收或反射机制。因此，在未来具有可调屏蔽效率和屏蔽机制的轻量级和灵活的 EMI 屏蔽中，应适当调整电导率和形态。