Quaternary Ammonium-Functionalized Poly(Arylene Ether Sulfone) Random Copolymers for Direct Air Capture

Direct air capture (DAC) is a promising tool for reducingCO(2) concentrations in the atmosphere and fighting climatechange.We synthesized a series of quaternary ammonium (QA)-functionalizedpoly(arylene ether sulfone) copolymers with varying mole fractionsof charge content and demonstrated their potential as sorbents forDAC. Molecular weight analysis determined that a high monomer conversionwas achieved in 240 & DEG;C and a single glass-transitiontemperature (T (g)); T (g) decreased with an increase in ion exchange capacity (IEC).Fractional free volume and water uptake percentage increased and watercontact angle decreased with the number of QA sites when comparedto a neutral, commercially available polysulfone (Udel P-1700 PSU).Next, the novel series of ammonium-functionalized copolymers exhibiteda moisture-mediated capture and release of atmospheric CO2. When exposed to air containing 30% relative humidity, the polymerscaptured CO2, and the capacity increased with the IEC.When the relative humidity was increased to 95% the samples releasedCO(2). This study demonstrates a promising CO2 DAC sorbent and highlights the possibility for continuous DAC withpurpose-built freestanding membranes.