TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The fluorinated monomers in (A) consist of vinylidene fluoride (VDF), 2-8C perfluoroolefins (preferably tetrafluoroethylene (TFE), 2-8C chloro- and/or bromo- and/or iodo-fluoroolefins (preferably chlorotrifluoroethylene (CTFE) and bromotrifluoro ethylene; (per)fluoroalkylvinylethers (CF2=CFORf, or perfluoro-oxyalkylvinylethers (CF2=CFOX). The fluorinated monomers in (B) maybe of formula:F2C=CF-O-CF2-CF2-SO2F, F2C=CF-O-(CF2-CX'F-O)n-CF2-CF2-SO2F, F2C=CF-O-CF2-CF2-CF2-SO2F, orF2C=CF-Ar-SO2F.Rf = 1-6C (per)fluoroalkyl, preferably trifluoromethyl, bromodifluoromethyl, or pentafluoropropyl;X = 1-12C perfluoro-oxyalkyl having ether group(s), preferably perfluoro-2-propoxy-propyl);X' = Cl, F or CF3;n = 1-10;Ar = aryl.Preferred Composition: The ionomers may also contain 0.01-0.4 mole.% of monomeric units derived from bis-olefin of formula R1R2C=CH-(CF2)m-CH=CR5R6.m = 2-10, preferably 4-8;R1, R2, R5, R6 = H or 1-5C alkyl.Preferred Condition: The crosslinking is by radical route and takes place at 100-200 degrees C in the presence 0.1-5 wt.% (based on the polymer) of peroxide. Before crosslinking, ionomers contain in the chain and/or in the terminal position radical attack sites, preferably iodine and/or bromine atoms. Further, crosslinking co-agent (0.5-10 wt.% based on the polymer), metal compound (1-15, preferably 2-10 wt.% based on the polymer), inorganic or polymer reinforcing fillers (preferably optionally fibrillable polytetrafluoro ethylene), and additives (e.g., thickeners, pigments, antioxidants, and stabilizers) are added before crosslinking. The fillers have 10-100, preferably 10-60 nm size. The ionomer can also be mixed with a fluoroelastomer, (preferably perfluoroelastomer) co-curable with the fluorinated ionomers, before crosslinking.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The crosslinking agent consists of triallyl-cyanurate, triallyl-isocyanurate (TAIC), tris(diallylamine)-s-triazine, triallylphosphite, N,N-diallyl-acrylamide, N,N,N',N'-tetrallyl-malonamide, trivinyl-isocyanurate, 2,4,6-trivinyl-methyltrisiloxane, N,N'bis-allylbicyclo-oct-7-ene-disuccinimide (BOSA), bis-olefin of formula R1R2C=CH-(CF2)m-CH=CR5R6, or triazine.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The metal compound consists of oxides or hydroxides of divalent metals (e.g., magnesium, zinc, calcium or lead), optionally combined with a weak acid salts (preferably stearates, benzoates, carbonates , oxalates, or phosphites of barium, sodium, potassium, lead, or calcium). EXAMPLE - In 2-L autoclave, water (700 ml), CF2=CF-O-CF2CF2-SO2F (45 ml), perfluoropolyoxyalkylene microemulsion (29 g) obtained by mixing 11.6 g of CF2ClO(CF2-CF(CF3)O)n(CF2O)mCF2COOK (n/m = 10), perfluoropolyether oil (5.8 g), and water (11.6 g), 5.7 ml solution of 33 vol.% I-(CF2)6-I in Galden D02, and 1.5 ml solution of 1.5 vol.% CH2=CH-(CF2)6-CH=CH2 in Galden D02, were introduced. The autoclave was heated to 50 degrees C, 400 ml aqueous solution at 20 g/l potassium persulfate was fed. TFE was added, and CF2=CF-O-CF2CF2-SO2F (7.5 ml), and 1.5 vol.% CH2=CH-(CF2)6-CH=CH2 in Galden D02 (1.5 ml solution), were added every 6.5 g of TFE added. The latex obtained was coagulated, and ionomer was separated from the mother liquor. The ionomer (50 g) was mixed with Luperox 101 XL (0.5 g) and TAIC Drymix. The film obtained was subjected to salification and acidification treatment to transform the sulfonyl groups to sulfonic groups (-SO3H).