Covalent and electrostatic incorporation of amines into hypercrosslinked polymers for increased CO2 selectivity

Two methods of incorporating functional groups rich in nitrogen into low cost microporous hypercrosslinked polymers (HCPs) have been evaluated and the effects on the carbon dioxide CO2/N2 IAST selectivity were measured. Electrostatic incorporation of an ammonium salt into a sulfonic acid‐containing HCP polymer afforded a static CO2 uptake of 2.5 mmol g−1 with a CO2/N2 IAST selectivity of 42:1 at 1 bar and 298 K. Using column breakthrough measurements with a 15:85 CO2/N2 mixture at 298 K and 1 bar, a selectivity of 17:1 was obtained. However, varying the counterion resulted in polymers with lower CO2/N2 selectivity values. Decoration of the parent polymer with CO2‐philic imidazole followed by electrostatic ammonium salt incorporation blocked some of the micropores reducing the selectivity which re‐emphasizes the role and importance of pore width for CO2/N2 selectivity