PEDOT-PSS embedded comb copolymer membranes with improved CO₂ capture

Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS) is a widely used conductive polymer in various electronic devices. Here we report the first use of PEDOT-PSS to enhance CO₂ capture performance of all-polymeric membranes. Specifically, an amphiphilic comb copolymer, i.e. poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate)-poly(oxyethylene methacrylate) (PBEM-POEM or PBE), was synthesized to disperse PEDOT-PSS chains. Isolated and aggregated PEDOT-PSS transformed into an interconnected network structure upon combination with PBE, due to specific interactions. Incorporation of PEDOT-PSS generated a facile pathway for enhanced diffusive transport, resulting in improved CO₂ and N₂ permeability. However, CO₂ permeability increased more significantly due to enhanced CO₂ solubility, resulting in slight increase in CO₂/N₂ selectivity. The PBE membrane containing PEDOT-PSS 5 wt% showed the highest performance with a CO₂ permeability of 59.6 Barrer and CO₂/N₂ selectivity of 77.4. The performance of PBE/PEDOT-PSS membranes was very close to the 2008 Robeson upper bound and much higher than those of PBE/PEDOT, PBE/PSS and commercial PEBAX membranes.