Analysis of gas transport in molecularly-mixed composite membranes
Analysis of gas transport in molecularly-mixed composite membranes
复制标题
分子混合复合膜中气体传输的分析
DOI：
10.1016/j.memsci.2022.120880
复制
发表时间：
2022
影响因子：
9.5
通讯作者：
Lively, Ryan P.
中科院分区：
文献类型：
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作者：
Rivera, Matthew P.;Lively, Ryan P.
具有固有孔隙度的单个分子，如多孔有机笼(POCs)，具有显著的潜力来改善各种分离介质的性能。一个典型的应用是将POCS与聚合物混合制成分子混合复合膜(MMCM)。笼状分子和聚合物链之间的紧密相互作用产生了一种“固溶体”，避免了长期存在的与混合基质膜相关的界面问题。此外，由于笼子可溶于聚合物溶液，这些复合材料的加工可以很容易地适应现有的基于聚合物的技术，从而避免了对两相加工系统的担忧。MMCMS仍然是一个相对较新的发展，膜内的潜在转运过程还没有被很好地了解。在这里，我们通过这些可靠的解决方案来详细解释客户交通。我们演示了笼形分子的存在如何影响聚合物链的运动，从而影响通过聚合物相的客体传输。我们还展示了笼负荷如何影响膜自由体积。我们发现混合基质膜的气体渗透率与麦克斯韦模型的预测值有很大的偏差。研究发现，由于POC和聚合物之间的密切分子相互作用，POC在聚合物相中显著改变了膜的性质，违反了麦克斯韦模型的基本假设之一。这项工作提供了关于MMCM中客户运输性质的初步信息，以帮助它们未来适应与工业相关的分离单元。
Individual molecules with intrinsic porosity, such as porous organic cages (POCs), have significant potential to improve the performance of a variety of separations media. An exemplar application is the blending of POCs with polymers to make molecularly-mixed composite membranes (MMCMs). The intimate interaction between individual cage molecules and polymer chains results in a “solid-solution” that avoids longstanding interfacial issues associated with mixed matrix membranes. Moreover, as the cages are soluble in polymer solutions, the processing of these composites can be easily adapted to established polymer-based technologies as concerns with two-phase processing systems are avoided. MMCMs are still a relatively new development, and underlying transport processes within the membrane are not well understood. Here, we offer a detailed interpretation of guest transport through these solid solutions. We demonstrate how the presence of cage molecules affects polymer chain motions that can impact guest transport through the polymer phase. We also show how cage loading affects membrane free volume. We find that gas permeation deviates significantly from predictions made with the Maxwell model for mixed matrix membranes. POCs were found to significantly alter membrane properties in the polymer phase because of intimate molecular interactions between the POC and polymer, violating one of the Maxwell model's underlying assumptions. This work provides preliminary information on the nature of guest transport in MMCMs to aid their future adaptation to industrially-relevant separation units.