Polyimide-Based Membrane Materials for CO Separation: A Comparison of Segmented and Aromatic (Co)polyimides.

A series of new poly(ethylene oxide) (PEO)-based copolyimides varying in hard segment structure are reported in this work as CO selective separation membranes. Their structural diversity was achieved by using different aromatic dianhydrides (4,4'-oxydiphthalic anhydride (ODPA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA)) and diamines (4,4'-oxydianiline (ODA), 4,4'-(4,4'-isopropylidene-diphenyl-1,1'- diyldioxy)dianiline (IPrDA), 2,3,5,6-tetramethyl-1,4-phenylenediamine (4MPD)), while keeping the content of PEO (2000 g/mol) constant (around 50%). To get a better insight into the effects of hard segment structure on gas transport properties, a series of aromatic polyimides with the same chemistry was also studied.