(629e) Gas Sorption and Transport in a New Series of 6FCDA-Based Fluorinated Copolyimide Membranes

We investigated the solubility and permeability coefficients of various gas pairs (He/CH4, C2H4/C2H6, C3H6/C3H8, CO2/CH4, N2/CH4, and O2/N2) in a series of 6FCDA-based fluorinated copolyimides synthesized in our lab. These FCP membrane materials were composed of 9,9-bis(trifluoromethyl)-2,3,6,7-xanthenetetracarboxylic dianhydride (6FCDA), 5,5'-(1,4-phenylenebis(oxy))bis(isobenzofuran-1,3-dione) (HQDEA), 4,4′-sulfonyldibenzene-1,2-diamine (TADPS), 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diamine (TFDB), and 2,2-Bis(3-amino-4-hydroxyphenyl)hexafluoropropane (4,4'6F). The resulting copolymers have a high weight-average molecular weight with a narrow polydispersity index. Various analytical techniques, including GPC, FTIR, NMR, XRD, DSC, and TGA, were used to examine the polymers. Our findings revealed that systematic changes in chemical structure significantly affected both permeability and permselectivity. The relationship between gas separation properties and chemical structure was explored in terms of intrasegmental mobility and intersegmental packing within the non-fluorinated polyimide materials. The experimental results suggest that by optimizing intrasegmental mobility and intersegmental packing, it is possible to design new polymers with both high permeability and selectivity.