Mixed matrix membranes based on ionic liquids and porous organic polymers for selective CO2 separation

Abstract

The development of more efficient materials is a crucial step in the development of gas separation membranes. In this work, we combine ionic liquids (ILs) and porous organic polymers (POPs) for the first time to fabricate a new type of mixed matrix iongel membranes, which are entirely composed of organic materials. The new azo-POPs reported in this work were specifically designed due to their "CO2-philic" feature to be incorporated in iongel materials. The membranes, comprising 80 wt% of [C2mim][TFSI] IL and 20 wt% of poly(ethylene glycol) diacrylate (PEGDA) network, were prepared using a solvent-free UV curing method. The unique properties of azoPOPs within the iongel material resulted in the fabrication of dense and defect-free membranes with improved gas separation performances, in terms of both CO2 permeability (62.3-90.6 barrer) and, CO2/CH4 (9.9-12.0), CO2/H2 (6.0-12.1) and CO2/N2 (16.8-53.1) ideal selectivities, with the latter revealing to be highly dependent on the morphological properties of the azo-POPs. Furthermore, iongel characterization in terms of morphology, chemical structure and thermal properties, confirmed the potential of the novel mixed matrix iongels for CO2 separation processes.