E.i. Dupont De Nemours and Company

Roger A Smith

Raimund H Silva

Paul R Resnick

Michael S Withers

Composite fluorocarbon cation exchange membrane having at least two layers of fluorinated polymer containing pendant side chains with sulfonyl groups wherein the equivalent weight of one such layer differs from the adjacent layer by at least 100.

Electrolytic cell with cation exchange membrane having high equivalent

Solutions are disclosed with solvents having completely halogenated, saturated, hydrocarbon backbones and solubility parameters within a particular range. Preferred solvent have at least one ether linkage. An exemplary solvent is ##STR1## wherein X is F, Cl, Br, and I; n is 0, 1, and 2; m is 1, 2, and 3; and Y is COOCH.sub.3 and SO.sub.2 F. The solutions include perfluorinated copolymers having high equivalent weight which have been prepared from tetrafluoroethylene and perfluorinated sulfonyl fluoride- or carboxyl-containing vinyl monomers.

Solvents of carboxyl ester compounds and fluoropolymers

Multilayer fluorinated cation exchange membranes prepared by coextrusion of precursor polymers.

Coextruded multilayer cation exchange membranes

Solutions and membranes formed therefrom are disclosed with solvents having completely halogenated, saturated, hydrocarbon backbones and solubility parameters within a particular range. Preferred solvent have at least one ether linkage. An exemplary solvent is ##STR1## wherein X is F, Cl, Br, and I; n is 0, 1, and 2; m is 1, 2, and 3; and Y is COOCH.sub.3 and SO.sub.2 F. The solutions include perfluorinated copolymers having high equivalent weight which have been prepared from tetrafluoroethylene and perfluorinated sulfonyl fluoride- or carboxyl-containing vinyl monomers.

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Kennett Square, PA, United States of America

Roger A Smith