A new structure of a polymer composite was designed to be used as a vapor sensor for detection of a set of volatile organic compounds (VOCs), namely ethanol, methanol, isopropyl alcohol (IPA), toluene and water as moisture in the atmosphere. Picric acid was used for physical decoration of graphene (Gr), as a conductive filler, and then, the modified graphene (Gr.PA) was added to polyvinyl alcohol (PVA) to design a conductive polymer composite (CPC) sensitive layer for detection of polar vapor analytes. The Fourier transfer infrared spectroscopy (FTIR) was used to study the physical adsorption of picric acid molecules on the surface of Gr. The experimental results revealed that the sensitivity of the prepared CPC transducer was dramatically improved through the decoration of Gr surfaces with PA molecules. The enhanced sensitivity was related to the addition of –OH and –NO₂ functional groups on the surface of Gr (due to picric acid molecules). Those polar functional groups increased the diffusion driving force of polar analytes into the polymer composite. On the other hand, upon adding PA molecules, Gr–Gr junctions were tuned as sensitive sites, and the adsorbed vapor molecules increased the distance of Gr platelets, which, consequently, decreased the electron tunneling conductivity of the prepared CPC. The experimental results also proved that one could change the electrical conductivity of Gr as a p-type semiconductor through adsorption of analyte molecules on its surface. All in all, the attained results demonstrated that tuning the conductive filler junctions could be regarded as an exceptional strategy to improve the sensitivity of CPC transducers.

中文翻译：

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通过苦味酸分子调节聚合物-石墨烯的界面，以提高制备好的导电聚合物复合气体检测仪的灵敏度

设计了一种新型的聚合物复合材料结构，用作蒸汽传感器，用于检测大气中的水分作为一组挥发性有机化合物（VOC），即乙醇，甲醇，异丙醇（IPA），甲苯和水。苦味酸作为导电填料用于石墨烯（Gr）的物理装饰，然后将改性石墨烯（Gr.PA）添加到聚乙烯醇（PVA）中以设计用于检测的导电聚合物复合材料（CPC）敏感层极性蒸气分析物。傅里叶转移红外光谱（FTIR）用于研究苦味酸分子在Gr表面的物理吸附。实验结果表明，通过用PA分子修饰Gr表面可以显着提高制备的CPC传感器的灵敏度。Gr表面有_2个官能团（归因于苦味酸分子）。那些极性官能团增加了极性分析物向聚合物复合物中的扩散驱动力。另一方面，添加PA分子后，Gr-Gr结被调谐为敏感部位，吸附的蒸气分子增加了Gr血小板的距离，因此降低了所制备CPC的电子隧穿电导率。实验结果还证明，通过将分析物分子吸附在其表面上，可以改变Gr作为p型半导体的电导率。总而言之，获得的结果表明，调节导电填充物的结点可以被视为提高CPC传感器灵敏度的一种例外策略。