Finely Tuning the Free Volume Architecture in Iptycene-Containing Polyimides for Highly Selective and Fast Hydrogen Transport

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• 作者：Shuangjiang Luo ; Jennifer R. Wiegand ; Barbara Kazanowska ; Cara M. Doherty ; Kristina Konstas ; Anita J. Hill ; Ruilan Guo
• 刊名：Macromolecules
• 出版年：2016
• 出版时间：May 10, 2016
• 年：2016
• 卷：49
• 期：9
• 页码：3395-3405
• 全文大小：573K
• 年卷期：0
• ISSN：1520-5835

文摘

Iptycene-based polyimides have attracted extensive attention recently in the membrane gas separation field due to their unique structural hierarchy and chemical characteristics that enable construction of well-defined yet tailorable free volume architecture for fast and selective molecular transport. We report here a new series of iptycene-based polyimides that are exquisitely tuned in the monomer structure to afford preferred microcavity architecture for hydrogen transport. In particular, a triptycene-containing dianhydride (TPDAn) was prepared to react with two iptycene-containing diamines (i.e., TPDAm and PPDAm) or 2,2′-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP) to produce entirely or partially iptycene-based polyimides. The incorporation of iptycene units effectively disrupted chain packing, which resulted in ultrafine microporosity in the membranes with a desired bimodal size distribution with maxima at ∼3 and ∼7 Å, respectively. Depending on the combination of diamine and dianhydride, the microporosity was feasibly tuned and optimized to meet the needs of challenging H₂ separations, especially for H₂/N₂ and H₂/CH₄ gas pairs. Particularly, a H₂ permeability of 27 barrers and H₂/N₂ and H₂/CH₄ selectivities of 142 and 300, respectively, were obtained for TPDAn-6FAP.