Impact of Substrate and Processing on Confinement of Nafion Thin Films
Impact of Substrate and Processing on Confinement of Nafion Thin Films
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DOI：
10.1002/adfm.201304311
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发表时间：
2014-08-13
影响因子：
19
通讯作者：
Weber, Adam Z.
中科院分区：
文献类型：
--
作者：
Kusoglu, Ahmet;Kushner, Douglas;Weber, Adam Z.
离子导电聚合物薄膜是一个重要的研究领域，因为它们在许多电化学装置中发挥着作用，并且可以作为本体薄膜中发生的界面现象的类似物。在本文中，Nafion（一种典型离聚物）的特性被研究为碳、金和铂基底上的薄膜（4 至 300 nm），这些基底是使用不同的铸造方法和热历史制造的。具体来说，通过石英晶体微天平、椭圆光度法和掠入射 X 射线散射来研究吸水、膨胀和形态，以开发结构/性能/加工关系。对于所有基材，随着膜厚度的减小，由于膜亲水/疏水结构的无序化，溶胀最初减小，随后膜厚度增加至约20 nm以下。与自组装薄膜相比，在旋铸薄膜的金上观察到溶胀减少和结构有序性降低；对于碳上的薄膜观察到相反的效果。所提出的系统数据集和分析代表了对金属催化剂/碳电极中感兴趣的模型基底上的 Nafion 薄膜行为的全面研究，这些见解有助于阐明这些及相关系统中潜在的聚合物物理和限制效应。
Thin films of ion-conducting polymers are an important area of study due to their function in many electrochemical devices and as analogues for interfacial phenomena that occur in bulk films. In this paper, the properties of Nafion, a prototypical ionomer, are investigated as thin films (4 to 300 nm) on carbon, gold, and platinum substrates that are fabricated using different casting methods and thermal histories. Specifically, water uptake, swelling, and morphology are investigated by quartz-crystal microbalance, ellipsometry, and grazing-incidence X-ray scattering to develop structure/property/ processing relationships. For all substrates, as the films' thickness decreased, there is an initial decrease in swelling followed by a subsequent increase for film thicknesses below approximate to 20 nm due to a disordering of the film hydrophilic/hydrophobic structure. Decreased swelling and less structural order is observed on gold for spin-cast films compared to self-assembled films; the opposite effect is observed for films on carbon. The presented systematic data set and analyses represent a thorough study of the behavior of Nafion thin films on model substrates of interest in metal catalyst/carbon electrodes, and these insights help to elucidate the underlying polymer physics and confinement effects in these and related systems.