A polymer electrolyte membrane according to the present invention has a cluster diameter of 2.96 to 4.00 nm and a converted puncture strength of 300 gf/50 m or more. The polymer electrolyte membrane according to the present invention has a low electric resistance and an excellent mechanical strength.

The present invention relates to a self-humidifying ion-exchange composite membrane including an aromatic hydrocarbon polymer ion-exchange membrane formed on the surface of a porous polymer support and a thin hydrophobic coating layer having a nanocracked morphology pattern on the surface of the ion-exchange membrane. The self-humidifying ion-exchange composite membrane of the present invention has good thermal/chemical stability, high mechanical strength, high ion-exchange capacity, and good long-term operational stability. Particularly, the self-humidifying ion-exchange composite membrane of the present invention is able to self-hydrate even under high-temperature and low-humidity conditions. Due to these advantages, it is expected that the self-humidifying ion-exchange composite membrane of the present invention will be commercialized as an electrolyte membrane for a fuel cell or a membrane for water treatment.

An ion exchange membrane has multiple layers of ionic polymers which each contain substantially different chemical compositions. i.e. varying side chain lengths, varying backbone chemistries or varying ionic functionality. Utilizing completely different chemistries has utility in many applications such as fuel cells where for example, one layer can help reduce fuel crossover through the membrane. Or one layer can impart substantial hydrophobicity to the electrode formulation. Or one layer can selectively diffuse a reactant while excluding others. Also, one chemistry may allow for impartation of significant mechanical properties or chemical resistance to another more ionically conductive ionomer. The ion exchange membrane may include at least two layers with substantially different chemical properties.

Improved additives can be used to prepare polymer electrolyte for membrane electrode assemblies in polymer electrolyte fuel cells. Use of these improved additives can not only improve durability and performance, but can also provide a marked performance improvement during initial conditioning of the fuel cells. The additives are chemical complexes comprising certain metal and organic ligand components.

A composite proton conductive membrane, comprising an inorganic filler having covalently bonded acidic functional groups and a high surface area of at least 150 m.sup.2/g; and a water insoluble ionically conductive polymer. This membrane provides advantages over traditional polymeric proton conductive membranes for redox flow battery, fuel cell, and electrolysis applications include: 1) enhanced proton conductivity/permeance due to the formation of additional nanochannels for proton conducting; 2) improved proton/electrolyte selectivity for redox flow battery application; 3) reduced membrane swelling and gas or electrolyte crossover; 4) improved chemical stability; 5) increased cell operation time with stable performance, and 6) reduced membrane cost.

An ion exchange membrane containing a fluorinated polymer, wherein in a case where by Raman spectroscopy, polarized light orthogonal to the thickness direction of the ion exchange membrane is irradiated to obtain a spectrum chart, whereby the ratio of the peak area a2 of Raman shift 680 to 760 cm.sup.?1 to the peak area al of Raman shift 1,025 to 1,095 cm.sup.?1 is taken as A1, and by Raman spectroscopy, to a cross section in the thickness direction of the ion exchange membrane, polarized light parallel with the thickness direction is irradiated to obtain a spectrum chart, whereby the ratio of the peak area b2 of Raman shift 920 to 1,025 cm.sup.?1 to the peak area b1 of Raman shift 1,025 to 1,095 cm.sup.?1 is taken as B1, B1/A1 is at least 1.05.

To provide a method for producing a perfluorinated compound, capable of easily producing a perfluorinated compound from which a high molecular weight polymer can be produced by a polymerization reaction, and a method for producing a fluorinated polymer using it.

A method for producing a perfluorinated compound, which comprises step A of reacting a perfluoroalkoxide salt with a perfluoroallylating agent to obtain a crude product A containing a perfluoroallyl ether compound, or step B of subjecting a chlorofluorocarbon compound to dechlorination reaction to obtain a crude product B containing a perfluorinated ?-olefin compound, to obtain a crude product X which is either the crude product A or the crude product B, and mixing the crude product X with a radical source to bring radicals generated by the radical source and the crude product X into contact with each other to obtain a crude product Y containing a perfluorinated compound which is either the perfluoroallyl ether compound or the perfluorinated ?-olefin compound.

To provide a method capable of efficiently producing an ion exchange membrane for alkali chloride electrolysis which has high current efficiency, little variation in current efficiency and high alkaline resistance. This is a method for producing an ion exchange membrane 1 having a layer (C) 12 containing a fluorinated polymer (A) having carboxylic acid type functional groups, by immersing an ion exchange membrane precursor film having a precursor layer (C) containing a fluorinated polymer (A) having groups convertible to carboxylic acid type functional groups, in an aqueous alkaline solution comprising an alkali metal hydroxide, a water-soluble organic solvent and water, wherein the proportion of structural units having carboxylic acid type functional groups in the fluorinated polymer (A) is from 13.0 to 14.50 mol %; in the layer (C) 12, the value of resistivity is from 4.010.sup.3 to 25.010.sup.3 .Math.cm, and the variation in resistivity is at most 4.010.sup.3 .Math.cm, and the concentration of the water-soluble organic solvent is from 1 to 60 mass % in the alkaline aqueous solution.

The present invention pertains to a membrane for an electrochemical device, to a process for manufacturing said membrane and to use of said membrane in a process for manufacturing an electrochemical device.

To provide a method capable of efficiently producing an ion exchange membrane for alkali chloride electrolysis which has high current efficiency, little variation in current efficiency and high alkaline resistance. This is a method for producing an ion exchange membrane 1 having a layer (C) 12 containing a fluorinated polymer (A) having carboxylic acid type functional groups, by immersing an ion exchange membrane precursor film having a precursor layer (C) containing a fluorinated polymer (A) having groups convertible to carboxylic acid type functional groups, in an aqueous alkaline solution comprising an alkali metal hydroxide, a water-soluble organic solvent and water, wherein the proportion of structural units having carboxylic acid type functional groups in the fluorinated polymer (A) is from 13.0 to 14.50 mol %; in the layer (C) 12, the value of resistivity is from 4.010.sup.3 to 25.010.sup.3 .Math.cm, and the variation in resistivity is at most 4.010.sup.3 .Math.cm, and the concentration of the water-soluble organic solvent is from 1 to 60 mass % in the alkaline aqueous solution.