CO₂-Philic Imidazolium-Based Poly(Ionic Liquid) Composite Membranes for Enhanced CO₂/N₂ Separation

Abstract

Poly(ionic liquid) (PIL)-based membranes for CO2 removal attract increased interest due to the tunability of their chemical structure and processability of polymers. In this work, the IL cation of 1-vinylimidazole was selected as the polymeric backbone to connect the cyano- and carboxyl-based side chains to explore their effects. The synthesized PILs were blended with polyacrylamide (PAM) to prepare composite membranes by coating the mixed solutions on polysulfone (PSF) membranes. The CO2 permeance and CO2/N2 selectivity of these prepared PIL-based membranes were tested to evaluate their CO2 separation performance. The results demonstrate that the cyano-based side chain showed better CO2 separation performance compared to a carboxyl-based side chain of PILs. The best membrane performance for CO2 permeance increased by 200% and CO2/N2 selectivity increased by 195%. Here, the prepared PIL-based membranes provide a potential prospect for improving the CO2 separation performance by adjusting the chemical structure of PILs. However, optimization related to cation, anion, and side chain groups should be conducted to break through the CO2/N2 separation performance for industrial carbon capture.