TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The separation consists of desalination of water by reverse osmosis, non-aqueous liquid separation, ethanol/water separations, pervaporation dehydration of aqueous/organic mixtures, carbon dioxide/methane, carbon dioxide/nitrogen, hydrogen/methane, oxygen/nitrogen, hydrogen sulfide/methane, olefin/paraffin or iso/normal paraffin separations.    TECHNOLOGY FOCUS - POLYMERS - Preferred Method: In the method, a selective layer surface of the polybenzoxazole membrane is coated with a thin layer of a material consisting of a polysiloxane, a fluoro-polymer, a thermally curable silicone rubber or a UV radiation curable epoxy silicone. Preferred Components: The polybenzoxazole membrane is made by subjecting an aromatic poly(o-hydroxyamide) membrane prepared from an aromatic poly(o-hydroxyamide) polymer to thermal cyclization at 200-550 degrees C under an inert atmosphere. The polybenzoxazole membrane has been crosslinked. The crosslinking takes place by UV crosslinking of the polybenzoxazole membrane, where the polybenzoxazole membrane comprises UV crosslinkable functional groups. The polybenzoxazole membrane comprises aryl-4,5-dihydro-oxazole repeating units of formula (I). The poly(o-hydroxyamide) polymer comprises an aryl-amide repeating units of formula (II). The polybenzoxazole membrane is in a geometry of flat sheet, spiral wound, disk, tube, hollow fiber or thin film composite.Ar1 = benzen-1,2,4,5-yl, biphenyl-3,4,3',4'-yl and/or a substituted biphenyl group of formula (A), where for (II) biphenyl-3,4,3',4'-yl and/or a substituted biphenyl group (A) are preferred;R = -(CF3)2- (preferred for (II)), -C(CH3)2-, -S(=O)2-, -O- and/or -S-;Ar2 = phenoxybenzene moiety, diphenylmethanone moiety, benzenesulfinylbenzene moiety, (2,2,2-trifluoro-1-phenyl-1-(trifluoromethyl)ethyl)benzene moiety (all preferred for (II)), (1-methyl-1-phenyl-ethyl)benzene moiety, 1-(1-methyl-1-(4-phenoxyphenyl)ethyl)-4-phenoxy-benzene moiety, naphthalene moiety, 1,4-diphenoxybenzene moiety, biphenyl moiety, benzene moiety, 2-benzoyloxyethyl benzoate moiety or phenylsulfanylbenzene moiety; andn = 15-500.