TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The base is an inorganic base that is selected from an alkali metal, hydroxides of an alkali earth metal, carbonate and sulfate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The base is an organic base that is selected from ammonia and general amines. The polar solvent is a non protonic polar solvent or a protonic polar solvent. The non protonic polar solvent is N-methyl pyrrolidone (NMP), dimethyl formamide (DMF), N,N-dimethyl acetamide (DMAc) or dimethyl sulfoxide (DMSO). The protonic polar solvent is methylene chloride (CH2Cl2), chloroform (CH3Cl) or tetrahydrofuran (THF). The azeotropic solvent is benzene, toluene or xylene. he double polar solvent is N,N'-dimethylformamide, dimethylacetamide (DMAc), DMSO or NMP.    TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): Preparation of the copolymer (I) involves: polycondensation reaction of a sulfonated dihydroxy monomer of formula (HO-SAr1-OH)k, a none sulfonated dihydroxy monomer of formula (HO-Ar-OH)s, crosslinkable dihalide monomer of formula (X-CM-X)b, and a none sulfonated dihalide monomer of formula (X-Ar-X)d, in the presence of a solvent that includes a base, an azeotropic solvent, and a polar solvent at 0 to approximately 300 degrees C for 1-100 hours. Preparation of the copolymer (II) involves: carrying out the process for preparation of (I); and additionally reacting monohydroxy monomer of formula HO-phenyl (substituted by R) (V) or monohalide monomer of formula X-phenyl (substituted by R) (VI) with the copolymer (I); where in the case of when the ratio of (k+s)/(b+d) is not greater than 1, the monomer (V) in which hydroxy is substituted, is used, and in the case of when the ratio of (k+s)/(b+d) is not less than 1, the monomer (VI) in which halide is substituted, is used; and in the case of when R2 is X, regardless of the value of (k+s)/(b+d), the monomer (V) in which hydroxy is substituted, is used. Preferred Method: The heat treatment is carried out at 80 to approximately 350 degrees C after the sulfonated poly(arylene ether) copolymer (I) or (II) is dissolved in the solvent and the solvent that is used in the heat treatment is a double polar solvent. he acid treatment is carried out by, after the heat treatment is finished, cooling the film to a normal temperature, and substituting a salt ion (Na+, K+, and alkyl ammonium ions) of a sulfone group of the polymer (I) or (II) with hydrogen. EXAMPLE - Into a flask, a hydroquinonesulfonic acid potassium salt was added in the molar ratio of 20 mmol (k=1) in conjunction with K2CO3 (1.15 equivalent), N,N-dimethylacetamide (DMAc) (60 ml) and benzene (20 ml). The activation step was carried out for 6 to approximately 8 hours by increasing the temperature to 105 to approximately 110 for 6 hours. In the reaction, water that was produced as the sideproduct was removed by the azeotropic distillation method with benzene that was one of the reaction solvents, and after the activation step was finished, benzene was removed from the reactor. Then, the molar ratio of 1-ethynyl-3,5-difluorobenzene and decafluorobiphenyl of 1 mmol:19 mmol (b:d=0.05:0.95), were added to the reactor, the reaction was carried out for greater than or equal to 12 hours while the reaction temperature was maintained at 110. After the reaction was finished, precipitated in ethanol (500 ml), washed several times with water and ethanol, and vacuum dried at 60 for 3 days, a sulfonated poly(arylene ether) of formula (IA) (yield not less than 90%), was obtained as the light brown solid. The polymer (IA) was dissolved in the solvent such as dimethyl sulfoxide (DMSO), filtered and poured on the clean glass support by using the casting method, it was left in the oven 40 degrees C for 24 hours. In order to perform the crosslinking of the inside of the polymer chain, the heat treatment was carried out at 80 to approximately 350 degrees C for greater than or equal to 30 minutes (preferably 250 to approximately 260 degrees C for greater than or equal to 2 hours). After the heat treatment was finished, it was cooled to normal temperature, the acid treatment was carried out to substitute the salt ion such as Na+ of the sulfone portion that was produced in reaction with hydrogen. The acid treatment method was utilized in which after the polymer was immersed in the 0.5 mole of the sulfuric acid aqueous solution and boiled for 2 hours. The polymer electrolyte film that was subjected to the acid treatment was immersed in the distilled water for 24 hours, and then its proton conductivity was measured. The ion exchange ability, water uptake and the proton conductivity of the polymer electrolyte film was compared to that of the Nafion that is currently commercialized. The ion exchange ability (meq/g), water uptake (wt.%) and the ion conductivity (S/cm) for polymer electrolyte film/Nafion was found to be 2.15/0.91, 101/32 and 0.139/0.094, respectively.