Carbon molecular sieve (CMS) membranes have impressive separation properties; however, both chemical and morphology structures need to be understood better. Here we characterize CMS with the simplest polyimide (PI) PMDA/pPDA (PMDA=pyromellitic dianhydride, pPDA=p-phenylenediamine), using FTIR, solid-state ¹⁵N-NMR and ¹³C-NMR, XPS, XRD, and Raman spectra to study chemical structure. We also compare gas separation properties for this CMS to a CMS derived from a more conventional PI precursor. The detailed characterization shows the presence of aromatic pyridinic, pyrrolic rings as well as graphitic, pyridonic components and a few other groups in both CMS types derived from the very different precursors. The CMS morphologies, while related to precursor and pyrolysis temperature details, show similarities consistent with a physical picture comprising distributed molecular sieving plate-like structures. These results assist in understanding diverse CMS membrane separation performance.

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聚酰亚胺衍生的碳分子筛的主要特点

碳分子筛 (CMS) 膜具有出色的分离性能；然而，化学和形态结构都需要更好地理解。在这里，我们用最简单的聚酰亚胺（PI）PMDA / PPDA（PMDA =苯四甲酸二酐，PPDA =表征CMS p苯二胺），使用FTIR，固态¹⁵的N- NMR和¹³C-NMR、XPS、XRD 和拉曼光谱来研究化学结构。我们还将这种 CMS 的气体分离特性与源自更传统 PI 前体的 CMS 进行了比较。详细的表征表明，在源自截然不同的前体的两种 CMS 类型中，都存在芳香族吡啶环、吡咯环以及石墨、吡啶酮组分和一些其他基团。CMS 形态虽然与前体和热解温度细节有关，但显示出与包含分布式分子筛板状结构的物理图片一致的相似性。这些结果有助于了解不同的 CMS 膜分离性能。