Bifunctional imidazolium/amine polymer foams: One-pot synthesis and synergistic promotion of CO2 sorption

Amines and imidazolium are well-known functional groups in carbon dioxide capture applications because of their excellent interactions with CO2, but their combination and possible synergistic effects when combined in polymer foams have not yet been considered. This work reports an innovative one-pot water-mediated synthesis of bifunctional imidazolium/amine microcellular polymer foams containing tunable ratios of these functions by combining the Radziszewski multicomponent reaction and high internal phase emulsion (HIPE) polymerization in a one-pot manner. The resulting polymer foams have unique textural and structural properties exhibiting rapid CO2 sorption kinetics with good capacities and excellent ability to selectively capture CO2 from the gas mixture in spite of their low specific surface. The bifunctional amine/imidazolium foams showed superior CO2 capture performances compared to their monofunctional counterparts, indicating the synergy between the functional groups. Comparison with the corresponding non-porous bulk materials also proved that the imidazolium/amine bifunctionality must be incorporated in a highly porous morphology to beneficiate from efficient and fast CO2 uptake. The marked influence of both the amine/imidazolium ratio and the nature of the imidazolium counteranion on CO2 capture capacity under dry and humid conditions is demonstrated, as well as the outstanding multicyclic capture performance.