Reported herein is a neutron reflectometry (NR) study on hydrated Nafion thin films (∼30 nm) on a silicon substrate with native oxide. The Nafion morphology is investigated systematically across the whole relative humidity range using both H₂O and D₂O vapours to enable a comparative study. By utilising this systematic approach two key results have been obtained. The first is that by leveraging the strong positive scattering signal from the D₂O vapour, a complete and systematic water adsorption isotherm (Type II) for a Nafion thin film is produced. Utilising the slight negative scattering signal of the H₂O enabled the quantification of the hydration dependent evolution of the formation of Nafion/water lamellae near the substrate surface. The number of lamellae layers increases continuously with hydration, and does not form abruptly. We also report the effects of swelling on the thin films across the relative humidity ranges. The work reported should prove useful in quantifying other hydration dependent properties of Nafion thin films such as conductivity and understanding Nafion/semiconductor based devices, as well as showcasing a NR methodology for other hydrophilic polymers.

中文翻译：

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Nafion 薄膜的系统原位水合中子反射测量研究

本文报道的是对具有天然氧化物的硅基板上的水合 Nafion 薄膜（~30 nm）的中子反射计 (NR) 研究。_{使用 H 2} O 和 D ₂ O 蒸气在整个相对湿度范围内系统地研究 Nafion 形态，以进行比较研究。通过利用这种系统方法，已经获得了两个关键结果。第一个是通过利用来自 D ₂ O 蒸气的强正散射信号，产生了用于 Nafion 薄膜的完整且系统的水吸附等温线（II 型）。利用 H _{2的轻微负散射信号}O 能够量化基底表面附近 Nafion/水薄层形成的水化依赖性演变。片晶层的数量随着水合作用不断增加，而不是突然形成。我们还报告了在相对湿度范围内膨胀对薄膜的影响。报告的工作应该证明有助于量化 Nafion 薄膜的其他水化相关特性，例如导电性和理解基于 Nafion/半导体的设备，以及展示其他亲水聚合物的 NR 方法。