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Cardo-type porous organic nanospheres: Tailoring interfacial compatibility in thermally rearranged mixed matrix membranes for improved hydrogen purification
- Dong, Liangliang, Zhang, Wenhai, Qu, Zheng, Wan, Chao, Yao, Zheng, Xu, Jibin, Kang, Xueting, Bai, Yunxiang, Zhang, Chunfang
- Journal of membrane science 2020 v.612 pp. 118414
- artificial membranes, carbon dioxide, condensation reactions, crosslinking, fluorenes, hydrogen, hydrogen bonding, models, nanospheres, permeability, polymers
- Mixed-matrix membrane (MMM) is an effective way to overcome trade-off limitations of conventional polymeric membranes. However, the existence of defect voids at the polymer/filler interface often limits their performance improvement. Similar issues are also present in thermally rearranged polybenzoxazole (TR-PBO)-derived MMMs. To address this challenge, the selection of fillers is of great importance. Herein, a novel organic porous nanosphere (TC-cPSB), which is prepared by the polycondensation of 9,9-bis(4-aminophenyl) fluorene (BAFL) and terephthalaldehyde (TPAL) followed by thermal crosslinking, is chosen to engineer the polymer/filler interface. Benefiting from strong intermolecular interaction (π-π stacking and hydrogen bonding), the TC-cPSB nanosphere can well disperse in TR-PBO matrix with a defect-free interface. With an increase in TC-cPSB loading, well-designed MMMs exhibit a significant “anti-trade-off” phenomenon whereby gas permeability and selectivity increase simultaneously, following the trend predicted by the Maxwell model. Compared with TR-PBO membrane, the MMM containing 15 wt% of nanosphere shows an increase of 282% and 217.6% in H₂/CO₂ selectivity and H₂ permeability, respectively, which is far beyond 2008 Robeson upper bound.