(351l) Thin-Film Polymer Membranes for Gas Separation Prepared By Interfacial Polymerization of Pillar[5]Arenes

Thin-film composite (TFC) membranes are considered as having good membrane architecture for membrane-based separations. Thin selective layer, of which thickness is usually less than one micrometer, is good for membrane productivity, and porous support membranes provide enough mechanical strength against high pressure operating conditions. For last few decades, a facile chemistry of interfacial polymerization has provided a great avenue for TFC membranes in liquid separation applications such as desalination or nanofiltration. However, the use of TFC membranes in gas separation has been limited. This is mainly attributed to the lack of knowledge that bridge chemistry-to-microstructure relationship of interfacial polymerization and, thereby, to the difficulty of tuning the microstructure of the TFC selective layer at molecular scale. Here, we propose to use pillar[5]arene nanoarchitectures to control the microstructure of these membranes by molecular design. Pillar[5]arenes have well defined molecular pore with ~4.7 angstrom in diameter. Also, a lot of functional groups enable pillar[5]arenes to directly participate in traditional interfacial polymerization process for TFC membrane fabrication. As a result, pillar[5]arene integrated TFC membranes showed good molecular sieving performance for light gas molecules; pure-gas selectivity were 26 for H₂/CO₂, 120 for CO₂/CH₄, 10 for O₂/N₂, and 3200 for H₂/CH₄, respectively. Also, cross-linked chemistry of interfacial polymerization provided substantial resistance to CO₂-induced plasticization for these membranes.