FIELD: asymmetric membranes for separation of gases. SUBSTANCE: asymmetric membrane is made of aromatic rigid polyimide or copolyimide based on dianhydride of diphenyl-ditrifluoromethyl-methane-3,4,3',4'-tetracarboxylic acid and 1,3-diaminobenzene or its mono- or dimethylated derivatives in the form of dense film and porous substructure and coated on the side of film with thin layer of silicone elastomer. Membrane has theoretic factor about 70-110 and effective selectivity approximately of 50-90 for pair CO2/CH4 at room temperature. Method of manufacture of membrane is also described. EFFECT: creation of asymmetric membrane of sufficiently rigid polyimides possessing high selectivity with respect to gases at temperature higher than room temperature. 15 cl, 11 tbl, 6 ex
