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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Hydrogen Permeation in Hydrated Perfluorosulfonic Acid Polymer Membranes: Effect of Polymer Crystallinity and Equivalent Weight
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Hydrogen Permeation in Hydrated Perfluorosulfonic Acid Polymer Membranes: Effect of Polymer Crystallinity and Equivalent Weight

机译：水合全氟磺酸聚合物膜中的氢渗透：聚合物结晶度和当量重量的作用

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Gas permeation through proton exchange membranes affects a fuel cell's electrochemical performance. To understand the gas permeation mechanism, gas permeability and wide-angle X-ray diffraction were measured for different equivalent weight (EW) perfluorosulfonic acid (PFSA) membranes at different water uptakes. A series of molecular dynamics (MD) simulations were also conducted. Through MD simulation, water sorption effects were found to result from an increased probability of dissolved H-2 molecules being near the water phase, where a higher H-2 diffusivity was observed. Furthermore, the local semicrystalline structure of the PFSA polymer and the morphology of the water clusters in the membrane were found to affect H-2 permeation in the high- and low-EW PFSA membranes, respectively. For the high-EW (EW > 909) membranes, the presence of the local crystalline structure decreased the void fraction in the structure and inhibits the H-2 diffusion across the aligned polymer chains. This effectively reduced H-2 solubility and diffusivity, thereby reducing H-2 permeability. The low-EW membranes contained a lower number of PTFE regions and exhibited a highly tortuous network in the aqueous domain. The former contributed to a reduction in H-2 solubility and the latter reduced the H-2 diffusivity. Therefore, H-2 permeability decreased with a decreased EW.
机译：通过质子交换膜的气体渗透影响燃料电池的电化学性能。为了了解燃气渗透机理，在不同水上抑制的不同当量重量（EW）全氟磺酸（PFSA）膜中测量透气性和广角X射线衍射。还进行了一系列分子动力学（MD）模拟。通过MD模拟，发现水吸附效应是由于溶解的H-2分子接近水相接近水相的可能性，其中观察到较高的H-2扩散率。此外，发现PFSA聚合物的局部半结晶结构和膜中的水簇的形态分别在高和低EW PFSA膜中影响H-2渗透。对于高EW（EW> 909）膜，局部结晶结构的存在降低了结构中的空隙率，并抑制了通过对齐的聚合物链的H-2扩散。这有效地降低了H-2溶解度和扩散性，从而降低了H-2渗透性。低EW膜含有较少数量的PTFE区域，并在水域中表现出高度曲折的网络。前者导致H-2溶解度的降低，后者降低了H-2扩散率。因此，H-2渗透率随着EW的降低而降低。

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