Ladder polymers of intrinsic microporosity from superacid-catalyzed Friedel-Crafts polymerization for membrane gas separation

Polymers of intrinsic microporosity have attracted comprehensive attention in membrane-mediated gas separation because of their rigid and contorted structure that facilitates well-defined microporosity for fast and selective gas transport. We report a new macromolecular design synthesizes semi-ladder and fully-ladder polymers of intrinsic microporosity containing 9H -xanthene units by superacid-catalyzed Friedel-Crafts polymerization named SACPs. The prepared SACP membranes display high microporosity with amorphous chain packing structure, high FFV, and high BET surfaces areas. In particular, SACP-3 exhibited the most elevated BET surfaces area of 568 m 2 /g, fractional free volume (FFV) of 0.243, and bimodal micropore size distribution with two maxima at ∼5 and ∼8 Å, respectively. Due to its fully ladder architecture, SACP-3 exhibits highly permeable gas transport with CO 2 permeability of 6497 Barrer and CO 2 /CH 4 selectivity of 7.8, respectively. The microporosity and gas permeation properties of SACP membranes are also demonstrated to be highly tailorable by employing different monomers . The facile polymerization procedure, excellent solubility and processability, highly diverse tunability, and outstanding gas separation performance render SACP membranes attractive for many membrane-mediated gas separation processes.