填料孔隙率和填料/聚合物界面体积在气体分离金属-有机骨架/聚合物混合基质膜中的作用,ACS Applied Materials & Interfaces

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填料孔隙率和填料/聚合物界面体积在气体分离金属-有机骨架/聚合物混合基质膜中的作用
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2018-09-07 00:00:00 , DOI: 10.1021/acsami.8b12938
Alexander Nuhnen ₁ , Dennis Dietrich ₁ , Simon Millan ₁ , Christoph Janiak ₁

Affiliation

金属有机骨架（MOF）和无机填料经常被掺入混合基质膜（MMM）中，以克服传统的渗透性折衷方案（P）和对纯有机聚合物膜的选择性。因此，就聚合物-填料界面的可能作用（即空隙体积）而言，研究MMM中多孔和无孔填料的影响非常重要。在这项工作中，我们比较了处于多孔和无孔状态的同一MOF填料，因此排除了来自不同聚合物-填料界面的假象。制备了具有多孔MOF富马酸铝（Al-fum）和无孔二甲基亚砜溶剂填充的富马酸铝（Al-fum（DMSO））的MMM，均以Matrimid为聚合物。填料含量为4至24重量％。通过使用CO ₂ / CH ₄的二元混合物进行混合气体测量研究了两种MMM的气体分离性能气体渗透率遵循Maxwell模型对多孔和无孔分散相（填充剂）的理论预测。带有多孔铝粉填料的MMM表现出增加的CO ₂和CH ₄渗透性，同时随着填料含量的增加，选择性也有适度的提高。具有无孔Al-fum（DMSO）填料的MMM表现出渗透率降低，同时保持了纯聚合物的选择性。log P与倒数特定自由分数体积（sFFV）的线性相关性排除了空隙体积的重要影响。sFFV包括聚合物和MOF的自由体积，但不包括聚合物-填料界面的体积（所谓的空隙体积）。MMM的sFFV计算为0.23 cm ³对于24重量％的Al-Fum / Matrimid MMM为/ g，对于24重量％的Al-fum（DMSO）/ Matrimid MMM为0.12 cm ³ / g。Al-Fum和Al-Fum /（DMSO）MMM的理论和实验密度的良好匹配支持了界面体积的微不足道的影响，其给出的比容体积低于0.02 cm ³ / g，经常甚至低于0.01 cm ³ /克。

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Role of Filler Porosity and Filler/Polymer Interface Volume in Metal–Organic Framework/Polymer Mixed-Matrix Membranes for Gas Separation

Metal–organic frameworks (MOFs) and inorganic fillers are frequently incorporated into mixed-matrix membranes (MMMs) to overcome the traditional trade-off in permeability (P) and selectivity for pure organic polymer membranes. Therefore, it is of great interest to examine the influence of porous and nonporous fillers in MMMs with respect to the possible role of the polymer–filler interface, that is, the void volume. In this work, we compare the same MOF filler in a porous and nonporous state, so that artifacts from a different polymer–filler interface are excluded. MMMs with the porous MOF aluminum fumarate (Al-fum) and with a nonporous dimethyl sulfoxide solvent-filled aluminum fumarate (Al-fum(DMSO)), both with Matrimid as polymer, were prepared. Filler contents ranged from 4 to 24 wt %. Gas separation performances of both MMMs were studied by mixed gas measurements using a binary mixture of CO₂/CH₄ with gas permeation following the theoretical prediction by the Maxwell model for both porous and nonporous dispersed phase (filler). MMMs with the porous Al-fum filler showed increased CO₂ and CH₄ permeability with a moderate rise in selectivity upon increasing filler fraction. The MMMs with the nonporous Al-fum(DMSO) filler displayed a reduction in permeability while maintaining the selectivity of the neat polymer. A linear dependence of log P versus the reciprocal specific free fractional volume (sFFV) rules out a significant contribution from a void volume. The sFFV includes the free volume of the polymer and the MOF, but not the polymer–filler interface volume (so-called void volume). The sFFV for the MMM was calculated between 0.23 cm³/g for a 24 wt % Al-fum/Matrimid MMM and 0.12 cm³/g for a 24 wt % Al-fum(DMSO)/Matrimid MMM. The negligible effect of an interface volume is supported by a good matching of theoretical and experimental density of the Al-fum and Al-fum/(DMSO) MMMs which gave a specific void volume below 0.02 cm³/g, often even below 0.01 cm³/g.

更新日期：2018-09-07

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