Synthesis of Imidazolium based PILs and Investigation of Their Blend Membranes for Gas Separation

Polymeric (ionic liquid) (PIL) copolymers bearing cationic imidazolium pendants and polar acrylic acid groups (P(VBCImY-co-AA(x))), which both favor the interaction with CO(2) molecules, have been synthesized and blended with film forming, high glass transition temperature aromatic polyether-based pyridinium PILs (PILPyr). The blend membranes based on the above combination have been prepared and characterized in respect to their thermal and morphological behavior as well as to their gas separation properties. The used copolymers and blends showed a wide range of glass transition temperatures from 32 to 286 °C, while blends exhibited two phase morphology despite the presence of polar groups in the blend components that could participate in specific interactions. Finally, the membranes were studied in terms of their gas separation behavior. It revealed that blend composition, counter anion type and acrylic acid molar percentage affect the gas separation properties. In particular, PILPyr-TFSI/P(VBCImTFSI-co-AA(20)) blend with 80/20 composition shows CO(2) permeability of 7.00 Barrer and quite high selectivity of 103 for the CO(2)/CH(4) gas pair. Even higher CO(2)/CH(4.) selectivity of 154 was achieved for PILPyr-BF(4)/P(VBCImBF(4)-co-AA(10)) blend with composition 70/30.