Finely Tuning the Microporosity and Gas Permeation Properties in Superacid-Catalyzed Polymers of Intrinsic Microporosity

Superacid-catalyzed polymers of intrinsic microporosity have attracted increasing attention in membrane-mediated gas separation due to their good processability, facile polymerization procedure, and tunable microporosity and gas separation performance. In this study, we synthesized a series of new superacid-catalyzed polymers with fully ladder backbones and well-defined micropores using a one-pot condensation polymerization. The incorporation of a contorted spirobisindane building block facilitated the formation of highly microporous structures in the resulting polymers, enhancing their intrinsic microporosity and gas separation properties. Among the three SACPs, SACP-PhMe exhibited the largest d-spacing value, specific surface area, and pore volume due to its bulkiest side group. The gas separation performance of the SACP membranes surpassed several benchmark polymer membranes, with the SACP-PhMe membrane demonstrating excellent performance in separating CO2/CH4, H2/CH4, O2/N2, and H2/N2. The SACP-Me membrane exhibited the lowest porosity, making it less susceptible to CO2 absorption and showing superior plasticization resistance. The results highlight the promising gas separation properties of the SACPs and their potential for various gas separation applications, offering new opportunities for advanced polymer membrane design.