TECHNOLOGY FOCUS - POLYMERS - Preferred Material: The material for polyelectrolyte is particularly a multi-segmented fluoropolymer with fluoropolymer segments (A) and (B) containing sulfonic acid type functional group and without, respectively, and the fluoropolymer segment (B) has a crystal melting point or glass transition point 100degreesC. The segment (A) is preferably a copolymer made from sulfonic acid type functional group-containing fluorinated ethylenic monomer units (a), particularly of formula (I), and at least 1 copolymerizable non-sulfonic acid type functional group-containing fluorinated ethylenic monomer units (b) which can be tetrafluoroethylene in an amount of 85-100 mol.% while the other monomer component can be one of formula (III) in 15-0 mol.%.CF2=CF-Rfa (III).Rfa = CF3 or ORfb;Rfb = 1-5C perfluoroalkyl.The equivalent number of the multi-segmented fluoropolymer is such material for solid polyelectrolyte is 400-1600. The multi-segmented fluoropolymer may also have at least 2 fluoropolymer segments containing sulfonic acid type functional groups (C) and (D), in which the equivalent number of (C) is smaller than that of segment (D), and (D) has a crystal melting point or glass transition point less than 100degreesC. Segments (C) and (D) are especially copolymers made from a sulfonic acid type functional group-containing fluorinated ethylenic monomer (c) and at least 1 copolymerizable fluorinated ethylenic monomer without the sulfonic acid type functional group (d), where (c) can be a monomer of formula (I). The equivalent number of segment (D) in the multi-segmented fluoropolymer is less than 1000. Preferably, the equivalent number of the total body of the multi-segmented fluoropolymer is 400-1600.Preferred Membrane: The sulfonic acid type functional group in the multi-segmented fluoropolymer in the material is a protonated sulfonic acid (SO3H), and such membrane has an elastic modulus of less than 1 x 108 dyn/cm2 at less than 110degreesC, with equivalent number of multi-segmented fluoropolymer total body being greater than 1600.Preferred Segmented Polymer: The monomer (e) is particularly of formula (II), while monomer (f) can be at least 1 fluorinated ethylenic monomer e.g. tetrafluoroethylene.CF2=CFO-Rf-SO2Y (II)The segment (B1) can be made from 85-100 mol.% tetrafluoroethylene and 15-0 mol.% a monomer of formula (III). Monomer(s) producing the segment (C1) is particularly of formula (II), and monomer (h) can be at least 1 fluorinated ethylenic monomer such as tetrafluoroethylene. The monomer (i) forming the segment (D1) is of formula (II), and monomer (j) can be 1 or more fluorinated ethylenic monomers including tetrafluoroethylene. EXAMPLE - Tetrafluoroethylene (TFE)/perfluoropropyl vinyl ether (PPVE) (97/3 mol.%) was polymerized to give the segment (B) as a block copolymer (B-A-B) type at a pressure of 7.5 kgf/cm2G, with ammonium persulfate as initiator in the presence of a polymer of CF2=CFOCF2CF(CF3)OCF2CF2SO2F (PFSF) with CF3CF2CF2OCF(CF3)CONH4 as emulsifier. At the end a copolymer of TFE/PFSF/PPVE in 85.1/13.9/1 mol.% was obtained with added segment (B). The resulting white polymer was soaked in aqueous 15% sodium hydroxide at 90degreesC for 8 hrs. to hydrolyze the -SO2F group, then was treated with 6N hydrochloric acid for 4 hrs. and dried at 110degreesC to afford a polyelectrolyte with -SO3H group. Properties of a prepared specimen: melting point of segment (B) = 303degreesC; segment (B) content = 30 wt.%; equivalent number = 1090; water content = 28%; tensile elastic modulus at 25degreesC = 1.7 x 109 dyn/cm2, at 110degreesC = 1 x 109 dyn/cm2, and at 200degreesC = 2.1 x 108 dyn/cm2.