Abstract Conventional mixed-matrix membranes (MMMs) possess a dense structure with a filler material uniformly dispersed within the polymer matrix to engineer the transport properties and achieve enhanced gas separation performances with respect to pure polymeric membranes. However, a dense membrane structure increases the transport resistance and undesirably requires a high filler loading to see a substantial enhancement in separation performances. To address this problem, we fabricated asymmetric MMMs that have a thin-selective layer of around 0.5 μm and a low loading (0.03–0.10 wt%) of nitrogen-doped graphene (N-G) nanosheets. The presence of the nitrogen- and oxygen-containing functional groups on the N-G nanosheets ensured good compatibility between filler and polymer matrix, which resulted in strong polymer/filler interfacial adhesions. The N-G nanosheets were also found to be capable of migrating to the top of the membranes during phase inversion. Hence, despite the low filler loadings used in this work, the capacity of the dense selective layers was greatly enhanced. Based on our experimental results, 0.07 wt% and 0.10 wt% loading of N-G nanosheets can improve both O2/N2 (126.9%) and CO2/N2 (45.8%) selectivities with respect to pure polymeric membranes, resulting in O2/N2 separation performance surpassing the Robeson upper bound.

中文翻译：

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掺氮石墨烯纳米片的非对称混合基质膜用于高选择性气体分离

摘要 传统的混合基质膜 (MMM) 具有致密结构，填充材料均匀分散在聚合物基质中，以设计传输性能并实现相对于纯聚合物膜的增强气体分离性能。然而，致密的膜结构会增加传输阻力，并且不希望地需要高填料负载才能看到分离性能的显着增强。为了解决这个问题，我们制造了具有约 0.5 μm 的薄选择性层和低负载（0.03-0.10 wt%）的氮掺杂石墨烯 (NG) 纳米片的非对称 MMM。NG纳米片上含氮和含氧官能团的存在确保了填料和聚合物基体之间的良好相容性，从而导致聚合物/填料界面粘附力强。还发现 NG 纳米片能够在相转化过程中迁移到膜的顶部。因此，尽管在这项工作中使用了低填充量，但致密选择性层的容量却大大增强。根据我们的实验结果，0.07 wt% 和 0.10 wt% 的 NG 纳米片负载可以提高 O2/N2 (126.9%) 和 CO2/N2 (45.8%) 相对于纯聚合物膜的选择性，从而提高 O2/N2 分离性能超越罗伯逊上限。