Abstract: Polyelectrolyte membranes suitable for use in a fuel cell are provided as a solid state sulfonation product of particular fluorinated polymers, or alternatively as a fluorination product of particular sulfonated polymers. A sulfonated polymer is provided that contains repeating units represented by structure, wherein the groups Ar3 and Ar4 are independently selected from the group consisting of aryl rings, aryl ring systems, and thiophene rings, and where at least one of Ar3 and Ar4 is substituted with a sulfonate group. Films suitable for use as a polyelectrolyte membrane are prepared from the sulfonated polymers.

Abstract: Polyelectrolyte membranes are multilayer composites, comprising a plurality of porous or expanded fluoropolymer support layers having macromolecules, polymer aggregates and particles of ionomers with proton exchange groups imbibed into pores of the support layers. Preferred membranes contain two or three support layers. Exemplary support layers include expanded fluoropolymer materials such as expanded polytetrafluoroethylene (ePTFE). In one embodiment perfluorosulfonic acid ionomers are imbibed into pores of the support layers.

Abstract: New proton conducting membranes are made of perfluorosulfonic acid polymers films that have been treated by exposing them to a chlorosulfonating agent. The membranes are used as a proton exchange membrane in PEM fuel cells operating at temperatures above 95° C., or at low relative humidity. In various embodiments, the treated films have superior physical properties such as tensile strength, when compared to an untreated film. In some embodiments, the ion exchange capacity (IEC) of the treated films is increased.

Abstract: Proton conducting membranes are made of sulfonated films comprising poly(arylene sulfide), an olefinic polymer, and an elastomer. They are used in PEM fuel cells operating at temperatures above 95° C., or at low relative humidity. According to methods of the invention, sulfonated poly(phenylene sulfide) (SPPS) films are provided with a wide range of physical properties, which depend in part on the ion exchange capacity of the films. In particular, the degree or level of sulfonation can be tailored by adjusting reaction conditions such as temperature and time.

Abstract: New proton conducting membranes are made of sulfonated poly(arylene sulfide) polymers (SPAS) and a perfluorosulfonic acid polymer. A preferred poly(arylene sulfide) polymer is poly(p-phenylene sulfide). The membranes are used as a proton exchange membrane in PEM fuel cells operating at temperatures above 60° C., or at low relative humidity. According to methods of the invention, sulfonated poly(phenylene sulfide) (SPPS) films may be provided with a wide range of physical properties, which depend in part on the ion exchange capacity of the films. In particular, the degree or level of sulfonation can be tailored by adjusting reaction conditions such as temperature and time. In a preferred embodiment, an ionomer comprising perfluorosulfonic acid polymer is imbibed into the insoluble SPAS films by immersing the films in a solution or dispersion of the ionomers.

Abstract: A method of enhancing electrical performance of a membrane for a fuel cell is disclosed. The method includes providing a perfluorosulfonic acid (PFSA) ionomer in an aqueous hydroxylated hydrocarbon aqueous solution. The PFSA dispersion or solution has an acid number the same or higher than an acid number of the membrane. The membrane is immersed in the solution such that the high acid number PFSA dispersion diffuses into the membrane. After immersion, the removed membrane is then dried under tension.

Abstract: A novel method of altering extruded membrane films for PEM (polymer electrolyte membrane) fuel cells in such a manner that the membrane films swell substantially uniformly in both the in-plane x and y directions when immersed in water or ionomer solution is disclosed. The invention includes cutting a membrane film from an extruded membrane sheet in a diagonal orientation with respect to the membrane process direction of the membrane sheet. The membrane film exhibits reduced internal stress as compared to conventionally-prepared membrane films and allows a more even distribution of pressure in a fuel cell stack, thereby reducing the incidence of swollen membrane-induced failure mechanisms in the fuel cell stack.

Abstract: Polyelectrolyte membranes suitable for use in a fuel cell are provided as a solid state sulfonation product of particular fluorinated polymers, or alternatively as a fluorination product of particular sulfonated polymers. A sulfonated polymer is provided that contains repeating units represented by structure, wherein the groups Ar3 and Ar4 are independently selected from the group consisting of aryl rings, aryl ring systems, and thiophene rings, and where at least one of Ar3 and Ar4 is substituted with a sulfonate group. Films suitable for use as a polyelectrolyte membrane are prepared from the sulfonated polymers.