TECHNOLOGY FOCUS - POLYMERS - Preferred Process: After removal of the organic solvent, an active energy ray irradiation treatment and/or heat treatment is performed. A hot rolling treatment is performed either after removal of organic solvent, or after active energy ray treatment and/or heat treatment. The structure unit of formula (Ia) is obtained by reacting a triazine compound of formula (Va) and a difluoride compound of formula F-Ar'-F (VIa) (where the sulfonic acid group in Ar1 and AR4 may be a salt of alkali metal or alkaline earth metal).X=OH or -O-Si(R1)3;R1=linear or branched alkyl.Preferred Components: (P1) Is a homopolymer, random copolymer, and/or block copolymer, and is cross-linkable by an active energy ray irradiation treatment and/or heat treatment. (P1) Has a number-average molecular weight (Mn) of 5000 - 10000000. Preferred Definitions:    Ar1=sulfonic acid group-containing phenyl having one or two sulfonic acid groups (optionally substituted by F or F-containing group);    Ar2=phenylene group (optionally substituted by F or F-containing group);    Y=direct bond;    R=CH=CH2, CH2CH=CH2 or CF=CF2;    Ar3 and Ar4=phenylene sulfone, phenylene sulfoxide, phenylene ketone, phenylene ether, benzoxazole, benzothiazole or triphenylphosphine oxide.    Provided that at least one of Ar3 and Ar4 has a structure unit selected from phenylene sulfone, phenylene sulfoxide, phenylene ketone, phenylene ether, benzoxazole, benzothiazole or triphenylphosphine oxide.    EXAMPLE - A mixture of potassium 2,4-bis(4-hydroxyphenyl)-6-(4-sulfonatephenyl)-1,3,5-triazine (4.59 g), 3,3'-disulfonated-4,4'-difluorodiphenylsulfone (2.29 g), bis(4-fluorophenyl)sulfone (1.27 g) and K2CO3 (1.65 g) in dimethyl sulfoxide (DMSO) (30 ml) and toluene (15 ml) was refluxed for 4 hours under nitrogen atmosphere and then the excess toluene was distilled off. The mixture was then heated at 180degreesC for 12 hours and poured the mixture into water (50 ml) and the polymer was separated, filtered and dried. The crude polymer was purified using DMSO. The polymer had viscosity of 0.53 dL/g. A solution of the obtained polymer was prepared in dimethylformamide (DMF) (20%) and applied to a glass plate and the solvent was distilled off at 50degreesC, 120degreesC and 200degreesC, each for 1 hour, to form a membrane with a thickness of approximately 55microns. The membrane was immersed in sulfuric acid (1 mol/l) for 24 hours, and washed with deionized water until free of acid to obtain electrolyte membrane (test). The membrane was tested for methanol permittivity (measured by keeping methanol solution (10 wt.% aqueous) and deionized water, separated from each other by the test membrane (55 microns thick) at 30degreesC, and measuring the amount of methanol seeped into the deionized water at specific time interval) and showed methanol permittivity = 7.02 x 10-8 ml/sec.cm, (the methanol permittivity of comparative Nafion 112 (RTM; electrolyte membrane) was 1.08 x 10-7). The test membrane showed proton conductivity (tested by placing the test sample between platinum electrodes that are 1 cm apart and measuring the film resistance of the test sample at room temperature at voltage of 0.3 V) = 0.136 S/cm.