(DE4213587-A)      Membrane comprises a poly(cyanoaryl ether). (I) In the prepn. an aromatic diol is reacted with a dihalobenzonitrile or dinitrobenzonitrile in the presence of a bsse and a polar aprotic solvent.    (I) is of formula (-Ara-O-Ara1-O-Arb-O-Arb1-O-) in (I) where Ara and Arb are each arylene, eg., p-or m-phenylene, 2,2'- or 4,4'-biphenylene, -Ph-C(CH3)2-Ph- or -Ph-C(CF3)2-Ph- where Ph is p-phenylene, (II)-(IV) or 1,5-, 1,4- or 1,8- naphthylene or a divalent anthracene, phenanthrene or phenolphthalein group, and Ara1 and Arb1 are selected from m- or p-phenylene substd. by -CN-, -NO2, -SO2R or -COR where R is 1-10C alkyl or 6-18C aryl, 4-cyano-1,3-naphthylene, 2,6-pyridyl- or -Ph-Q-Ph- where Q is -SO2- or -CO-; at least one of Ara1 and Arb1 is cyano-substd., e.,g 2- r 4-cyano-1,3-phenylene.    USE/ADVANTAGE -   Membranes can be cheaply mfd. are moisture resistant and have good gas sepn. properties, eg., N2/O2, H2/CO, H2/CH4 or CO2/CH4. Membranes can be used as sheets or hollow fibres.    (JP3157273-B2)      Membrane comprises a poly(cyanoaryl ether). (I) In the prepn. an aromatic diol is reacted with a dihalobenzonitrile or dinitrobenzonitrile in the presence of a base and a polar aprotic solvent.    (I) is of formula (-Ara-O-Ara1-O-Arb-O-Arb1-O-)n (I) where Ara and Arb are each arylene, eg., p-or m-phenylene, 2,2'- or 4,4'-biphenylene, -Ph-C(CH3)2-Ph- or -Ph-C(CF3)2-Ph- where Ph is p-phenylene, (II)-(IV) or 1,5-, 1,4- or 1,8- naphthylene or a divalent anthracene, phenanthrene or phenolphthalein group, and Ara1 and Arb1 are selected from m- or p-phenylene substd. by -CN-, -NO2, -SO2R or -COR where R is 1-10C alkyl or 6-18C aryl, 4-cyano-1,3-naphthylene, 2,6-pyridyl- or -Ph-Q-Ph- where Q is -SO2- or -CO-; at least one of Ara1 and Arb1 is cyano-substd., e.g, 2- or 4-cyano-1,3-phenylene.    USE/ADVANTAGE -   Membranes can be cheaply mfd., are moisture resistant and have good gas sepn. properties, eg., N2/O2, H2/CO, H2/CH4 or CO2/CH4. Membranes can be used as sheets or hollow fibres. @(10pp Dwg.No.0/0)