This paper presents the humidity sensing properties of surface-modified polyaniline (PAni). In this study, the impedance response and dielectric properties of pure- and doped-PAni have been investigated as a function of relative humidity (RH%) and frequency. PAni and PAni/Mn composite samples are synthesized by one-step interfacial polymerization process. The structural properties and surface morphologies of the prepared materials have been characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. XRD confirms the formation of PAni and it shows semi-crystalline behaviour. FESEM shows granular, porous and well-distributed structure. It has been observed that the porosity and nanogranular structure increased with increasing doping percentage. Here, we observe that porous and granular structure of Mn-doped PAni shows better response and recovery time ( $${\sim }28\hbox { s}$$ ∼ 28 s ) and decreases in electrical impedance. Dielectric constants, dielectric loss and AC conductivity have also been discussed with variations in frequency and relative humidity.

中文翻译：

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PAni/Mn纳米纤维不同相对湿度下的阻抗变化

本文介绍了表面改性聚苯胺 (PAni) 的湿度传感特性。在这项研究中，研究了纯 PAni 和掺杂 PAni 的阻抗响应和介电特性作为相对湿度 (RH%) 和频率的函数。PAni 和 PAni/Mn 复合样品是通过一步界面聚合工艺合成的。所制备材料的结构特性和表面形貌分别通过 X 射线衍射 (XRD) 和场发射扫描电子显微镜 (FESEM) 进行表征。XRD 证实了 PAni 的形成，并显示出半结晶行为。FESEM 显示颗粒状、多孔且分布良好的结构。已经观察到孔隙率和纳米颗粒结构随着掺杂百分比的增加而增加。这里，我们观察到 Mn 掺杂的 PAni 的多孔和颗粒结构显示出更好的响应和恢复时间 ($${\sim }28\hbox { s}$$ ∼ 28 s ) 并且电阻抗降低。还讨论了介电常数、介电损耗和 AC 电导率随频率和相对湿度的变化。