This paper describes the influence of crown-ether ring size and rigidity on the gas separation performance of CO₂/N₂ and plasticization behavior of crown-ether containing Matrimid® 5218 polyimide membranes. The crown-ethers provide the membrane material with good affinity for CO₂ due to the polar ether segments. Three different crown-ethers were used that differ in ring size and in rigidity (DB21C7, DB18C6 and 18C6). The gas separation performance of the crown-ether containing membranes was evaluated using pure gas and mixed gas conditions at pressures up to 40 bar. Thermal analysis (TGA and DSC) shows that the incorporation of the crown-ethers in the polyimide matrix was successful and that the crown-ethers have good compatibility with the polymer matrix. Gas sorption in the crown-ether containing membranes shows an enhanced solubility selectivity due to the enhanced interaction with CO₂ compared to the pristine Matrimid®. However, both solubility and permeability of CO₂ and N₂ are decreased in these crown-ether containing membranes over the whole pressure range. When the molecular size of the crown-ether decreases (DB21C7 > DB18C6 > 18C6) the permeability increases. In addition, the incorporation of the more rigid crown-ethers (DB18C6 and DB21C7) causes rigidification of the polymer matrix contributing to the lower permeability of DB18C6 and DB21C7-based membranes. Pure gas CO₂ permeation measurements show a typical plasticization behavior for pristine Matrimid®, while for the crown-ether containing membranes the extent of plasticization is significantly reduced. Next to that the plasticization pressure is shifted to higher CO₂ feed pressures. No plasticization was observed for the crown-ether containing membranes in the mixed gas conditions, as a result of the lower solubility of the crown-ether containing membranes and competition effects of CO₂ and N₂. The differences in size and rigidity of the different crown-ethers showed no significant influence on the plasticization resistance of crown-ether containing membranes. Altogether, the operating window of these crown-ether containing membranes is increased with respect to Matrimid® showing their potential to operate at higher CO₂ partial pressure without compromising selectivity.

本文描述了冠醚环的大小和刚性对CO ₂ / N ₂气体分离性能以及含冠醚的Matrimid®5218聚酰亚胺膜的塑化行为的影响。冠醚为膜材料提供了对CO _2的良好亲和力由于极性醚段。使用了三种不同的冠醚，它们的环尺寸和刚度都不同（DB21C7，DB18C6和18C6）。使用纯气体和混合气体条件在最高40 bar的压力下评估了含冠醚膜的气体分离性能。热分析（TGA和DSC）表明，冠醚在聚酰亚胺基体中的掺入是成功的，并且冠醚与聚合物基体具有良好的相容性。与原始Matrimid®相比，由于与CO _2的相互作用增强，含冠醚膜中的气体吸附显示出更高的溶解度选择性。然而，CO ₂和N _2的溶解度和渗透性在整个压力范围内，这些含有冠醚的膜中的碳原子数减少。当冠醚的分子大小减小时（DB21C7> DB18C6> 18C6），磁导率增加。另外，更坚硬的冠醚（DB18C6和DB21C7）的掺入导致聚合物基质的刚性化，从而导致基于DB18C6和DB21C7的膜的渗透性降低。纯气体的CO ₂渗透测量表明，原始Matrimid®具有典型的增塑性能，而对于含冠醚的膜，增塑程度则明显降低。紧接着塑化压力转移到较高的CO _2上进料压力。在混合气体条件下，未发现含冠醚膜的增塑作用，这是因为含冠醚膜的溶解度较低以及CO ₂和N _2的竞争作用。不同冠醚的尺寸和刚度差异对含冠醚膜的抗塑化性能没有显着影响。总而言之，相对于Matrimid®而言，这些含有冠醚的膜的操作窗口增加了，显示了它们可以在较高的CO ₂分压下操作而不损害选择性的潜力。