Facile Synthesis and Study of Microporous Catalytic Arene-Norbornene Annulation–Tröger’s Base Ladder Polymers for Membrane Air Separation

We report the facile synthesis and study of two soluble microporous ladder polymers, CANAL–TBs, by combining catalytic arene-norbornene annulation (CANAL) and Tröger's base (TB) formation. The polymers were synthesized in two steps from commercially available chemicals in high yields. CANAL–TBs easily formed mechanically robust films, were thermally stable up to 440 °C, and exhibited very high Brunauer–Teller–Emmett surface areas of 900–1000 m2 g–1. The gas separation performance of the CANAL–TBs for the O2/N2 pair is located between the 2008 and 2015 permeability/selectivity upper bounds. After 300 days of aging, CANAL–TBs still exhibited O2 permeability of 200–500 barrer with O2/N2 selectivity of about 5. The polymer with more methyl substituents exhibited higher permeability and slightly larger intersegmental spacing as revealed by WAXS, presumably due to more frustrated chain packing. The facile synthesis, excellent mechanical properties, and promising air separation performance of the CANAL–TB polymers make them attractive membrane materials for various air separation applications, such as aircraft on-board nitrogen generation and oxygen enrichment for combustion.