Alkyl imidazolium-functionalized cardo-based poly(ether ketone)s as novel polymer membranes for O-2/N-2 and CO2/N-2 separations

Alkyl imidazolium-functionalized poly(ether ketone)s (Im-PEKs) were prepared as novel polymer membranes for O-2/N-2 and CO2/N-2 separations. The Im-PEK polymers were synthesized by poly-condensation between difluoro- and dihydroxy-monomers, followed by benzylic bromination and alkyl imidazolium-functionalization. The polymers with pendant imidazolium-based ionic salts showed high CO2 solubility and hence a very high CO2/N-2 permselectivity of 66.1 due to their high solubility selectivity. In addition, the Im-PEK with long alkyl chain ([C-12-Im-PEK][Br]) displayed an extraordinary high O-2/N-2 permselectivity of 15.5 due to its enhanced diffusivity selectivity. Overall, the combined O-2/N-2 and CO2/N-2 separation properties were achieved in single polymeric membrane. The Im-PEK membranes also displayed good thermal and mechanical stabilities. (C) 2013 Elsevier Ltd. All rights reserved.This work was supported by the Korea Carbon Capture and Sequestration R&D Center under the Korea CCS2020 Program of the Ministry of Education and Science and Technology, Republic of Korea. Part of this work was also supported by the University of Incheon in 2011