TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No general method for preparation of monomer (I) is given.    TECHNOLOGY FOCUS - POLYMERS - Preferred Membrane: The electrolyte membrane further comprises at least one polymer selected from polyimide, polyetherketone, polysulfone, polyethersulfone, polyetherethersulfone, polybenzimidazole, polyphenylene oxide, polyphenylenesulfide, polystyrene, polytrifluorostyrene sulfonic acid, polystyrene sulfonic acid, polyurethane, or branched sulfonated poly(sulfone-ketone)copolymer; at least one inorganic compound selected from silicon oxide (SiO2), titanium oxide (TiO2), inorganic phosphate, sulfonated silicon oxide (sulfonated SiO2), sulfonated zirconium oxide (sufonated ZrO2), and sulfonated zirconium phosphate (sulfonated ZrP); and porous support. Preferred Definitions:    A=sulfonic acid or sulfonate;    Y'=selected from 18 groups as given in the specification e.g. -CH2-, -(CH2)2-, -(CH2)3-, -(CH2)4-, -(CH2)5-, -(CH2)6-, phenylene-diyl, naphthalene-diyl, anthracene-diyl, perylene-diyl or phenanthrene-diyl.    SPECIFIC COMPOUNDS - 2-(2,5-Dihydroxy-(1,1';4',1'')terphenyl-4''-yloxy)-1,1,2,2-tetrafluoro-ethanesulfonic acid (I') is disclosed as monomer (I).    EXAMPLE - Boron bromide was slowly added dropwise to a solution of 4''-(2-bromo-1,1,2,2-tetrafluoro-ethoxy)-2,5-dimethoxy-(1,1';4',1'')terphenyl (1 equivalent (eq.)) in chloroform and the mixture was reacted at room temperature for 4 hours. Distilled water was added to the reaction mixture to terminate the reaction. After work-up 4''-(2-bromo-1,1,2,2-tetrafluoro-ethoxy)-(1,1';4',1'')terphenyl-2,5-diol (IA) was obtained. Compound (IA) (1 eq.), sodium hydrosulfite (4 eq.) and sodium bicarbonate (1 eq.) were dissolved in a mixed solvent of dimethylsulfoxide and distilled water, and the mixed solution was reacted at 80 degrees C for 3 hours, and the reaction solution was cooled to room temperature. After work-up 2-(2,5-dihydroxy-(1,1';4',1'')terphenyl-4''-yloxy)-1,1,2,2-tetrafluoro-ethanesulfonic acid was obtained.