Disclosed are: an ionomer dispersion having high dispersion stability while also containing high content of ionomer solids, thus optimizing the ionomer morphology in a polymer electrolyte membrane to allow both the ion conductivity and durability of the polymer electrolyte membrane to be improved; a method for producing the ionomer dispersion; and a polymer electrolyte membrane produced using the method.

Provided are membranes useful for electrochemical or fuel cells. A membrane may be formed of or include a sulfonated polymer whereby the sulfonated polymer is covalently or ionically associated with a multi-nitrogen containing heterocyclic molecule. The resulting membranes possess excellent ion conductivity and selectivity.

A fluorosulfonyl group-containing polymer having units represented by the following formula u1, a sulfonic acid group-containing polymer having fluorosulfonyl groups in the fluorosulfonyl group-containing polymer converted into sulfonic acid groups, its production method and its applications: ##STR00001##
wherein R.sup.F1 and R.sup.F2 are a C.sub.1-3 perfluoroalkylene group.

The present invention provides a fluoropolymer containing fluorosulfonyl groups capable of forming a polymer electrolyte membrane with high conductivity and hot water resistance, a method for its production, a fluoropolymer containing acid-form sulfonic acid groups and a method for its production, a polymer electrolyte membrane, a membrane-electrode assembly and a polymer electrolyte fuel cell. The method for producing a fluoropolymer containing fluorosulfonyl groups of the present invention comprises copolymerizing a monomer m1 (CF.sub.2═CFCF.sub.2O-Q.sup.1-SO.sub.2F) and TFE in a reactor at a temperature of from 150 to 200° C. in the presence of a radical polymerization initiator, wherein the radical polymerization initiator is continuously or sequentially added into the reactor so that the concentration of the radical polymerization initiator is kept to at most 2.5 mass ppm of the initial feed of the monomer m1 present in the reactor before initiation of the copolymerization during the copolymerization, and the molar ratio of the total feed of the monomer m1 to the total feed of tetrafluoroethylene is from 1.5 to 20

A separator for an electrochemical device comprising a porous polymer substrate, and a porous coating layer on at least one surface of the porous polymer substrate. The porous coating layer comprises inorganic particles and an ion conducting polymer. The ion conducting polymer comprises a fluorine-based copolymer comprising fluoroolefin-based segments with anionic functional groups present in side chains or terminals, and an electrochemical device comprising the same. It is possible to provide a separator with high ionic conductivity and an increased peel strength between the porous polymer substrate and the porous coating layer, and an electrochemical device with improved properties.

A method for producing a fluorosulfonyl group-containing compound to obtain a compound represented by the following formula 5 from a compound represented by the following formula 1 as a starting material and a method for producing a fluorosulfonyl group-containing monomer in which the fluorosulfonyl group-containing compound is used:

##STR00001##

wherein R.sup.1 and R.sup.2 are a C.sub.1-3 alkylene group, and R.sup.F1 and R.sup.F2 are a C.sub.1-3 perfluoroalkylene group.

To provide a polymer wherein a linking group that connects the main chain of the polymer and a cyclic perfluoroaliphatic disulfonimide skeleton, is a fluoroalkylene group which may have an ether oxygen atom. A polymer which has either one or both of units represented by formula u1-1 and units represented by formula u1-2:

##STR00001##

R.sup.F1, R.sup.F2: a C.sub.1-3 perfluoroalkylene group; R.sup.F3: a C.sub.1-6 perfluoroalkylene group; m: 0 or 1; and X: a hydrogen atom, an alkali metal atom, a fluorine atom, an alkyl group, ammonium or the like.

The present disclosure discloses an asymmetric electrolyte membrane, a membrane electrode assembly including the same, a water electrolysis apparatus including the same and a method for manufacturing the same. More particularly, it discloses an asymmetric electrolyte membrane having a porous layer and a dense layer at the same time, a membrane electrode assembly including the same, a water electrolysis apparatus including the same and a method for manufacturing the same.

Silica particles bonded to polymer chains consisting of at least one polymer comprising at least one fluorinated styrene repeating unit comprising at least one proton-conducting group, optionally in the form of a salt, the bonding between the particles and each of the chains being carried out by an organic spacer group.

To provide an acid-type sulfonic acid group-containing polymer which is excellent in hydrogen gas barrier properties and hot water resistance and which generates less oligomer during production; a liquid composition and a polymer electrolyte membrane comprising this acid-type sulfonic acid group-containing polymer; and a membrane electrode assembly and a polymer electrolyte fuel cell provided with the polymer electrolyte membrane.

This acid-type sulfonic acid group-containing polymer is a polymer which has perfluoromonomer units, no monomer units having a halogen atom other than a fluorine atom, and acid-type sulfonic acid groups, and of which the hydrogen gas permeability coefficient under the conditions of a temperature of 80° C. and a relative humidity of 10%, is at most 2.5×10.sup.−9 cm.sup.3.Math.cm/(s.Math.cm.sup.2.Math.cmHg), and the mass reduction rate when being immersed in hot water at 120° C. for 24 hours is at most 15 mass %, wherein the TQ value of a polymer having fluorosulfonyl groups which is a precursor of the polymer having acid-type sulfonic acid groups, is at least 220° C.