TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The Lewis base catalyst is potassium carbonate or sodium carbonate.    TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): The block sulfonated polystyrene copolymer is obtained by preparing nonsulfonated block (B) by dissolving monomers (b) and (c) in a protic solvent, reacting at 80-120 degrees C for 2-24 hours and 120-180 degrees C for 12-24 hours in presence of Lewis base catalyst, cooling to room temperature, then adding monomer (d), heating at 100-150 degrees C, continuously reacting for 24-48 hours, filtering the reaction solution, collecting the solid, neutralizing by washing with water, vacuum-drying, dissolving in aprotic solvent, adding methanol or ethanol as precipitant, performing heavy precipitation and purification or directly putting the monomer (d) into methanol or ethanol, stirring overnight and washing the excess monomer (d), preparing sulfonated metal salt (a), then copolymerizing sulfonated metal salt (a) with proton conductive properties and nonsulfonated block (B) at 50-100 degrees C for 2-24 hours, adding the reaction solution into aqueous hydrochloric acid, stirring overnight, filtering, collecting solid, dissolving in the solvent and performing heavy precipitation in toluene. The molar ratio of monomer (c) to monomer (b) is 101:100-2:1. The usage amount of catalyst is 2.4-3 times than the number of moles of monomer (c). The molar number of monomer (d) is 1-1.5 times than that of residual hydroxyl or thiol group. The molar ratio of monomer (a) to block (B) is 5:1-100:1. Preferred Composition: The sulfonated metal salt (a) is sulfonated dichloro aromatic compound of formula (II), (III), (IV), (V), (VI) or (VII). The monomer (b) is bis(4-chlorophenyl)methanone, bis(3-chlorophenyl)methanone, bis(4-fluorophenyl)methanone, bis(3-fluorophenyl)methanone, 1-chloro-4-((4-chlorobenzene)sulfonyl)benzene, 1-chloro-3-((3-chlorobenzene)sulfonyl)benzene, 1-fluoro-4-((4-fluorobenzene)sulfonyl)benzene, 1-fluoro-3-((3-fluorobenzene)sulfonyl)benzene, 1,2,3,4,5,6-hexachlorobenzene, 1,2,3,4,5-pentachloro-6-(2,3,4,5,6-pentachlorophenyl)benzene, 1,2,3,4,5,6-hexafluorobenzene or 1,2,3,4,5-pentafluoro-6-(2,3,4,5,6-pentafluorophenyl)benzene. The monomer (c) is 4-(2-(4-hydroxyphenyl)propan-2-yl)phenol, 4-(1,1,1,3,3,3-hexafluoro-2-(4-hydroxyphenyl)propan-2-yl)phenol, 4-(4-hydroxyphenyl)phenol, 4-((4-hydroxyphenyl)sulfanyl)phenol, 4-(4-hydroxyphenoxy)phenol, benzene-1,4-diol, 4-(2-(4-sulfanylphenyl)propan-2-yl)benzene-1-thiol, 4-(1,1,1,3,3,3-hexafluoro-2-(4-sulfanylphenyl)propan-2-yl)benzene-1-thiol, 4-(4-sulfanylphenyl)benzene-1-thiol, 4-((4-sulfanylphenyl)sulfanyl)benzene-1-thiol, 4-(4-sulfanylphenoxy)benzene-1-thiol, benzene-1,4-dithiol, benzene-1,3-dithiol, 4-(9-(4-sulfanylphenyl)-9H-fluoren-9-yl)benzene-1-thiol or 4-(9-(4-hydroxyphenyl)-9H-fluoren-9-yl)phenol. The monomer (d) is (4-chlorophenyl)(4-fluorophenyl)methanone or (3-chlorophenyl)(4-fluorophenyl)methanone.M=Na+, K+ or Li+.Preferred Process: The proton exchange membrane is prepared by dissolving the block sulfonated polystyrene copolymer in a solvent, coating the formed mixture on a substrate and drying. The thickness of the thickness of the proton exchange membrane is 10-100 microns.