A series of copolyimides were successfully synthesized via a polycondensation reaction of a dianhydride and two cardo-types of diamines. The molar composition of the copolyimide was controlled to investigate the effect of hydroxyl group on gas permeation properties. The synthesized cardo copolyimides were soluble in common organic solvents and had excellent thermal stabilities. CO<sub>2</sub> permselectivity of the copolyimide membrane containing hydroxyl group was higher than that of polyimide without hydroxyl group. CO<sub>2 </sub>permeability of the polyimide membrane was improved by the incorporation of hydroxyl group, which increased the solubility of carbon dioxide. The copolyimides containing the hydroxyl group were thermally converted to poly(benzoxazole-imide) at 425 °C for improvements in the gas permeability. The hydroxyl group in the polymer membrane leaded to the internal free volumes within the polybenzoxazole polymer matrix, which resulted in the increase of gas permeation properties.

Synthesis and characterization of novel cardo-containing copolyimide membranes for gas separation

251st National Meeting (2016)

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