Hybrid inorganic-organic polymer electrolyte membranes (PEMs) based on alkyloxysilane grafted thermoplastic polymers
View Patent ↗A composition of matter is formed from a graftable polymer, having graftable sites onto which sidechains have been grafted. The sidechains include at least one silane group, and may be formed by polymerization of a polymerizable group of a silane precursor. These compositions may further include acid groups, and may be used, for example, in improved proton conducting materials in fuel cells.
1. A process for forming a polymer electrolyte membrane, the process comprising:
providing a graftable polymer, the graftable polymer having a plurality of graftable sites;
providing a silane compound, the silane compound including a silane group and a functional group,
the functional group being selected from a group consisting of vinyl, acrylate, methacrylate, epoxy, styrene, and urethane;
grafting sidechains onto graftable sites of the graftable polymer, the sidechains being derived at least in part from polymerization of the functional group of the silane compound, so as to provide a polymer material having a plurality of silane groups within the sidechain; and
hydrolyzing the plurality of silane groups so as to form the polymer electrolyte membrane.
2. The process of claim 1 , wherein the graftable polymer is a thermoplastic polymer.
3. The process of claim 1 , wherein hydrolyzing the plurality of silane groups is part of a copolymerization reaction with a second silane compound.
4. The process of claim 3 , wherein the second silane compound is an alkyloxysilane.
5. The process of claim 1 , wherein the silane compound further includes a functional group, and grafting sidechains onto graftable sites of the graftable polymer comprises polymerization of the functional group.
6. The process of claim 5 , wherein the sidechains each include a chain formed by polymerization of the functional group.
7. The process of claim 1 , wherein the graftable polymer has organic sidechains, the organic sidechains providing the graftable sites.
8. The process of claim 1 , wherein the graftable polymer is provided by a treatment of a treatable polymer.
9. The process of claim 8 , wherein the treatable polymer is a thermoplastic.
10. The process of claim 8 , wherein the treatment includes exposure of the treatable polymer to ozone.
11. A fuel cell including the polymer electrolyte membrane of claim 1 .
12. A process for producing a polymer electrolyte membrane, the process comprising:
providing an organic polymer having graftable sites;
grafting sidechains to the graftable sites, each sidechain providing at least one silane group; and
hydrolyzing silane groups provided by the sidechains so as to at least partially cross-link the organic polymer, to form the polymer electrolyte membrane,
wherein grafting sidechains to the graftable sites includes providing a silane compound having a silane group and further including a functional group,
the functional group being a vinyl, acrylate, methacrylate, epoxy, styrene, or urethane group,
the sidechains being grafted to the organic polymer using a radical polymerization technique.
13. The process of claim 12 , wherein grafting sidechains to the graftable sites includes a polymerization of the functional groups.
14. The process of claim 12 , wherein grafting sidechains to the graftable sites includes reacting the functional groups with the graftable sites.
15. The process of claim 12 , wherein each sidechain includes at least two flexibly interconnected silane groups.
16. The method of claim 1 , wherein the silane further includes an acid group.
17. The method of claim 1 , hydrolysis of the plurality of silane groups occurring after grafting the sidechains to the graftable polymer.
18. The method of claim 10 , wherein the polymer is poly(vinylidine fluoride) or poly(vinylidine fluoride-hexafluoropropylene).