(196c) New Dimensions in Fabricating Ionic Polymers of Intrinsic Microporosity for Advanced Membrane Gas Separation

Next generations of high-performance membranes featuring fast and selective transport combined with robust chemical, mechanical, and thermal stability are highly desired for various energy-demanding industrial gas separation processes. Gas transport properties (i.e., permeability and selectivity) of synthetic polymer membranes suffer a ubiquitous trade-off, known as the Robeson’s upper bounds, which originates mainly from the difficulty in simultaneously increasing fractional free volume while manipulating the microcavity size distribution. On this basis, novel polymer architecture with high fractional free volume (FFV) and well-defined micropore size distribution is highly demanded for the fabrication of high-performance gas separation membranes.

Ionic liquids (ILs) are molten salts at ambient temperature and have attracted substantial attention in membrane-mediated gas separation due to their characteristic electrostatic interaction, favorable gas affinity, and abundant structure variations. This talk focuses on the macromolecular design, synthesis, characterization, and separation performance of a novel family of ionic polymers of intrinsic microporosity (IPIM) as gas separation membranes, which have shown promising separation performance for various gas pairs [1,2]. The functionalization of polymers of intrinsic microporosity with ionic species provides additional tunability towards the microcavity architecture through the interchain electrostatic interactions and the counterions. The wealthy structural hierarchy and the versatile chemical compositions of the ionic functionalization offer unique opportunities for generating tailored “molecular cavities” in the IPIM membranes, in which hierarchically architecture is developed with microcavities favoring fast gas transport and ultra-micropores boosting gas sieving. These novel IPIM membranes will be discussed in terms of their synthesis, characterization, and gas separation properties, focusing on how to finely tune the hierarchical microcavities via introducing various ionic substituents, manipulating the degree of ionization, and varying molecular configurations in the membranes. The fundamental correlations between the microscopic structures of these new ionic polymer of intrinsic microporosity and macroscopic membrane transport properties will be presented.

References

1. Xie, Y. Jiao, Z. Cai, H. Liu, L. Gong, W. Lai, L. Shan, S. Luo*. Highly Selective Benzimidazole-Based Polyimide/Ionic Polyimide Membranes for Pure- and Mixed-Gas CO₂/CH₄ Separation. Separation and Purification Technology, 2022, 282, 120091.

2. Z. Cai, Y. Liu, C. Wang, W. Xie, Y. Jiao, L. Shan, P. Gao, S. Luo*. Ladder Polymers of Intrinsic Microporosity from Superacid-Catalyzed Friedel-Crafts Polymerization for Membrane Gas Separation, Journal of Membrane Science, 2022, 644, 120155.