Markus Paul, Martínez-Tong Daniel E, Papastavrou Georg, Alegria Angel
Physical Chemistry II, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
Departamento de Física de Materiales, Basque Country University (UPV/EHU), P. Manuel de Lardizábal 3, E-20018 San Sebastián, Spain.
Soft Matter. 2020 Apr 1;16(13):3203-3208. doi: 10.1039/c9sm02471a.
The effect of humidity on the ionic transport in the amorphous phase of poly(ethylene oxide) thin films has been studied by local dielectric spectroscopy. We explored a controlled humidity range between 15% RH and 50% RH. AFM-based local dielectric imaging allowed the thin film topography and the corresponding dielectric contrast maps to be obtained simultaneously. No humidity effect on the film topography was observed whereas large variation of the dielectric signal could be detected. In addition, we observed a clear dielectric contrast in different locations on the thin film surface. At selected regions with high contrast in the dielectric maps, we performed nanoDielectric Spectroscopy (nDS) measurements covering the frequency range from 5 Hz to 100 kHz. By modeling these spectroscopy results, we quantified the conductivity of the amorphous phase of the semicrystalline poly(ethylene oxide) films. The crystalline fraction of the PEO thin films was extracted and found to be about 36%, independently of humidity. However, the average conductivity increased by a factor of 25 from 2 × 10-10 to 5 × 10-9 S cm-1, by changing environmental humidity in the explored % RH range.
通过局部介电谱研究了湿度对聚环氧乙烷薄膜非晶相离子传输的影响。我们探索了15%相对湿度至50%相对湿度的可控湿度范围。基于原子力显微镜的局部介电成像能够同时获得薄膜形貌和相应的介电对比度图。未观察到湿度对薄膜形貌的影响，而介电信号有很大变化。此外，我们在薄膜表面不同位置观察到明显的介电对比度。在介电图中具有高对比度的选定区域，我们进行了覆盖5赫兹至100千赫兹频率范围的纳米介电谱（nDS）测量。通过对这些光谱结果进行建模，我们量化了半结晶聚环氧乙烷薄膜非晶相的电导率。提取了聚环氧乙烷薄膜的结晶分数，发现其约为36%，与湿度无关。然而，通过在探索的相对湿度范围内改变环境湿度，平均电导率从2×10⁻¹⁰增加到5×10⁻⁹ S cm⁻¹，增加了25倍。
