Patent ID: 8016124

Claim:
A gas separation membrane comprising a blend of polyethersulfone (PES) and aromatic polyimide polymers that comprise a plurality of first repeating units of formula (I) wherein X 1 is selected from the group consisting of and mixtures thereof; X 2 is selected from the group consisting of and mixtures thereof; and X 3 is selected from the group consisting of and mixtures thereof, wherein the phenyl groups of X 1 , X 2 and X 3 are optionally substituted with one or more substituents independently selected from the group consisting of C 1 -C 3 alkyl, C 1 -C 3 alkoxy, halogen, nitro and —NR 1 R 2 , wherein R a , R b , R c and R d are each independently C 1 -C 3 alkyl, R 1 and R 2 are H or C 1 -C 3 alkyl, provided that both R 1 and R 2 are not H, and the gas separation membrane has a layer of said blend of PES and aromatic polyimide polymers with a thickness from about 0.1 micron to about 3.0 microns.