Patent ID: 8734574

Claim:
A gas separation membrane obtained by a process comprising: heat treating a membrane comprising a hyperbranched polyimide-based material in a non-oxidizing atmosphere, wherein the hyperbranched polyimide-based material comprises a hyperbranched polyimide obtained by imidizing a hyperbranched polyamic acid having a hydroxyl group or an alkoxy group at at least one of a plurality of ends thereof, the hyperbranched polyamic acid is obtained by reacting an aromatic tetracarboxylic dianhydride, an aromatic triamine and an alkoxy compound of silicon, magnesium, aluminum, zirconium or titanium, which has an amino group or a carboxyl group at an end, or a derivative of the alkoxy compound, and the hyperbranched polyimide-based material is a polymer blend of the hyperbranched polyimide and a straight-chain hydroxypolyimide.