TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The dihalo sulfo compound (IX) is preferably of formulae (XI)-(XIV). The dihalogen compound (II) is preferably of formula (XVI) or (XVII).l,k=1 or 2.    TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): Monomer composition containing dihalo sulfonyl compound of formula (III) and dihalo sulfo compound of formula: X-Ar2-X (IX) is polymerized in presence of nickel compound, and group of formula: -S(=O)2-OM (VIII) in obtained polymer is converted into sulfur group, to obtain copolymer.Ar2=bivalent aromatic group (optionally substituted by 1-20C alkyl, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy, 2-20C acyl, 7-20C arylcarbonyl (all optionally substituted by fluoro, cyano, 1-20C alkyl, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy, 2-20C acyl or 7-20C arylcarbonyl), fluoro or cyano) containing group(s) (VIII);-OM=-OM1 or -O-M2+;M1=1-20C alkyl;andM2+=alkali-metal cation or cation of ammonium compound.Preferred Composition The repeating unit (I) is preferably of formula (IV)-(VII). EXAMPLE - 32.7 g 2,2'-Bipyridine and solution containing 188 g tetrahydrofuran and 188 g N-methyl-2-pyrrolidone were heated, 13.2 g (2,5-dichlorophenyl)phenyl sulfone, 25 g 4,4'-dichloro-2,2',6,6'-biphenyl tetrasulfonic acid tetrakis(2,2-dimethyl-1-propyl) and 52.8 g bis(cyclooctadiene)nickel(0) were added, stirred, obtained reaction mixture was poured into 1250 g methanol, deposited solid was washed using methanol and water, obtained solid was mixed with 656 g 20 wt.% nitric acid, stirred, 656 g methanol and 460 g water were added, stirred, filtered, obtained cake was washed using methanol and dried, to obtain 27 g polyarylene copolymer. 25.3 g Hydrochloric acid, 388 g N-methyl-2-pyrrolidone and obtained polyarylene copolymer were stirred, obtained reaction mixture was poured into 1335 g acetone, deposited solid was washed using acetone, obtained solid was added with 1335 g 13 wt.% hydrochloric acid and 1335 g water, stirred, filtered, obtained cake was washed with water, and dried, to obtain 23.1 g polyarylene copolymer having ion exchange capacity of 4.88 mequivalent/g, with yield of 84%.