TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The gases are mixtures consisting of carbon dioxide/methane, dioxide/nitrogen, hydrogen/methane, oxygen/nitrogen, hydrogen sulfide/methane, olefin/paraffin and iso paraffins/normal paraffins. The gas or liquid comprises: at least one volatile organic compound in an atmospheric gas; hydrogen from a hydrocarbon vapor stream; a mixture of at least one pair of gases consisting of nitrogen and oxygen, carbon dioxide and methane, and hydrogen and methane or a mixture of carbon monoxide, helium and methane; natural gas comprising methane and at least one gas component consisting of carbon dioxide, oxygen, nitrogen, water vapor, hydrogen sulfide, helium and other trace gases; and hydrocarbon gases, carbon dioxide and/or hydrogen sulfide.    TECHNOLOGY FOCUS - POLYMERS - Preferred Method: The crosslinking treatment is chemical crosslinking or UV radiation. The method further comprises coating a top surface of the polymer membranes made from aromatic polyimide membranes by thermal treating and UV crosslinking with a thin layer of high permeability material consisting of a polysiloxane, a fluoro-polymer, a thermally curable silicone rubber, and a UV radiation curable epoxy silicone. Preferred Components: The polyimide polymer is poly(3,3',4,4'-benzophenonetetracarboxylic dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane), poly(3,3',4,4'-benzophenonetetracarboxylic dianhydride-3, 3'-dihydroxy-4,4'-diamino-biphenyl), poly(3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane), poly(3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane-3,3'-dihydroxy-4,4'-diamino-biphenyl), poly(2,2'-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride-3,3',4,4'-benzophenonetetracarboxylic dianhydride-2,2-bis(3-amino-4- hydroxyphenyl)-hexafluoropropane), poly(4,4'-oxydiphthalic anhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane), poly(4,4'-oxydiphthalic anhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane-3,3'-dihydroxy-4,4'-diamino-biphenyl), poly(3,3',4,4'-benzophenonetetracarboxylic dianhydride-2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane-3,3'-dihydroxy-4,4'-diamino-biphenyl) and poly(4,4'-bisphenol A dianhydride-3,3',4,4'-benzophenonetetracarboxylic dianhydride-2,2-bis-3-amino-4-hydroxyphenyl)-hexafluoropropane. The polyimide polymer has an amide repeating units of a formula (I).X1 = biphenyl ether group, biphenyl carbonyl group or biphenyl sulfonyl group;X2 = X1, (2,2,2-trifluoro-1-phenyl-1-(trifluoromethyl)ethyl)benzene group, (1-methyl-1-phenyl-ethyl)benzene group, 1-(1-methyl-1-(4-phenoxyphenyl)ethyl)-4-phenoxy-benzene group, naphthalenyl group, diphenoxybenzenyl group, biphenyl group, benzenyl group, benzoyloxyethyl benzoate group or biphenyl thioether group;Y1 = phenyl group of formula (II)-(IV);Z, Z1, Z2 = -O- or -S-; andR = -C(-CF3)2-, -C(-CH3)2-, -S(=O)2, -O- or -S-.