US5679482A — Fuel cell incorporating novel ion-conducting memb…

Claim 1

Independent Claim 223 words

A highly sulfonated polymeric membrane produced by the process of: (a) preparing a polymer solution by combining (i) a copolymer which comprises at least one vinyl aromatic polymer segment chosen from the group: ##STR6## bonded to at least one flexible connecting polymer segment chosen from the group: ##STR7## and the group: ##STR8## wherein R 1 , R 2 , R 3 and R 4 are chosen independently from the group consisting of hydrogen, phenyl and lower alkyl; R 5 is hydrogen, chlorine or lower alkyl; R 6 is hydrogen or methyl; R 7 is -SO 3 H, --P(O)(OR 8 )OH, --R 9 --SO 3 H or --R 9 --P(O)(OR 8 )OH where R 8 is hydrogen or lower alkyl and R 9 is lower alkylene; Ar is phenyl; and m, n, p and q are zero or integers from 50 to 10,000, with (ii) a sulfonation agent, under controlled reaction conditions, and within a compatible solvent system; (b) removing a portion of the solvents from the polymer solution; and (c) casting the resulting material on a substrate, to form a membrane that absorbs at least about 50% of its weight in water, that in its fully-hydrated state can be stretched by at least about 10% of its original dimension without fracture, and that exhibits a conductivity of at least about 10 -5 S/cm.

Claim 2

Dependent Claim 223 words

A highly sulfonated polymeric membrane produced by the process of: (a) preparing a polymer solution by combining (i) a copolymer which comprises at least one vinyl aromatic polymer segment chosen from the group: ##STR6## bonded to at least one flexible connecting polymer segment chosen from the group: ##STR7## and the group: ##STR8## wherein R 1 , R 2 , R 3 and R 4 are chosen independently from the group consisting of hydrogen, phenyl and lower alkyl; R 5 is hydrogen, chlorine or lower alkyl; R 6 is hydrogen or methyl; R 7 is -SO 3 H, --P(O)(OR 8 )OH, --R 9 --SO 3 H or --R 9 --P(O)(OR 8 )OH where R 8 is hydrogen or lower alkyl and R 9 is lower alkylene; Ar is phenyl; and m, n, p and q are zero or integers from 50 to 10,000, with (ii) a sulfonation agent, under controlled reaction conditions, and within a compatible solvent system; (b) removing a portion of the solvents from the polymer solution; and (c) casting the resulting material on a substrate, to form a membrane that absorbs at least about 50% of its weight in water, that in its fully-hydrated state can be stretched by at least about 10% of its original dimension without fracture, and that exhibits a conductivity of at least about 10 -5 S/cm.

Claim 3

Dependent Claim 41 words

The polymeric membrane of claim 1, wherein the controlled reaction conditions include the mixture of components (i) and (ii) at a temperature below about 5° C., followed by mixing at an elevated temperature until a purplish color appears in the mixture.

Claim 4

Dependent Claim 50 words

The polymeric membrane of claim 1, wherein the compatible solvent system comprises: (I) a solvent mixture of a halogenated solvent and a hydrocarbon solvent; and (II) a second solvent or solvent mixture used after component (i) has become sulfonated, selected from the group consisting of ethanol, n-propanol, butanol, and pentanol.

Claim 5

Dependent Claim 18 words

The polymeric membrane of claim 1, wherein the vinyl aromatic polymer segment is derived from polystyrene or poly(alpha-methylstyrene).

Claim 6

Dependent Claim 30 words

The polymer membrane of claim 1, wherein the flexible connecting polymer segment is derived from a polymer selected from the group consisting of poly(alpha-olefins), polydienes, and hydrogenated derivatives of polydienes.

Claim 7

Dependent Claim 14 words

The polymer membrane of claim 1, wherein component (i) is a styrene-(ethylene-butylene)-styrene triblock copolymer.

Claim 8

Dependent Claim 25 words

The polymer membrane of claim 1, wherein step (a) results in a copolymer which is sulfonated to the extent of at least 25 mol %.

Claim 9

Dependent Claim 34 words

The polymer membrane of claim 1, wherein the sulfonation agent is selected from the group consisting of sulfuric acid/acetic anhydride; sulfur trioxide/acetic acid; sulfur trioxide/lauric acid; chlorosulfonic acid/lauric acid; chlorosulfonic acid; and trimethylsilyl-sulfonyl chloride.

Claim 10

Dependent Claim 25 words

The polymer membrane of claim 1, wherein the sulfonation agent comprises sulfur trioxide, and is used in combination with a moderator for the sulfonation reaction.

Claim 11

Dependent Claim 23 words

The polymer membrane of claim 9, wherein the moderator is selected from the group consisting of phosphorus pentoxide, triethyl phosphate, and tris(2-ethylhexyl) phosphate.

Claim 12

Dependent Claim 17 words

The polymer membrane of claim 1, wherein step (a) further includes the incorporation of an antioxidant agent.

Claim 13

Dependent Claim 26 words

The polymer membrane of claim 11, wherein the antioxidant agent is selected from the group consisting of hindered phenolic compounds and oligomers containing hindered phenolic compounds.

Claim 14

Dependent Claim 16 words

The polymer membrane of claim 12, wherein the oligomer is a low molecular weight phenol-formaldehyde resin.

Claim 15

Dependent Claim 27 words

The polymer membrane of claim 1, wherein step (a) further includes the incorporation of an acidic agent capable of reacting with methanol to form a methyl ester.

Claim 16

Dependent Claim 21 words

The polymer membrane of claim 14, wherein the acidic agent is a carboxylic acid or a polymer containing a carboxylic acid.

Claim 17

Dependent Claim 17 words

The polymer membrane of claim 14, wherein the acidic agent is incorporated by blending with component (i).

Claim 18

Dependent Claim 23 words

The polymer membrane of claim 14, wherein the acidic agent is a carboxylic acid-containing monomer, and is incorporated by polymerization with component (i).

Claim 19

Dependent Claim 11 words

A direct-methanol fuel cell, comprising the polymer membrane of claim 14.

Claim 20

Dependent Claim 46 words

A highly sulfonated polymeric membrane according to claim 1 wherein said vinyl aromatic polymer segment is selected from the group comprising sulfonic acids of polystyrene and poly(α-methylstyrene), and said flexible connecting polymer segment is selected from the group comprising poly(alphaolefins), polydienes, and hydrogenated derivatives of polydiene.

Claim 21

Dependent Claim 226 words

A process for preparing a mechanically stable, ion-conducting membrane, comprising the steps of: (a) preparing a polymer solution by combining (i) a copolymer which comprises at least one vinyl aromatic polymer segment chosen from the group: ##STR9## bonded to at least one flexible connecting polymer segment chosen from the group:. ##STR10## and the group; ##STR11## wherein R 1 , R 2 , R 3 and R 4 are chosen independently from the group consisting of hydrogen, phenyl and lower alkyl; R 5 is hydrogen, chlorine or lower alkyl; R 6 is hydrogen or methyl; R 7 is --SO 3 H, --P(O)(OR 8 )OH, --R 9 --SO 3 H or --R 9 --P(O)(OR 8 )OH where R 8 is hydrogen or lower alkyl and R 9 is lower alkylene; Ar is phenyl; and m, n, p and q are zero or integers from 50 to 10,000, with (ii) a sulfonation agent, under controlled reaction conditions, and within a compatible solvent system; (b) removing a portion of the solvents from the polymer solution; and (c) casting the resulting material on a substrate, to form a membrane that absorbs at least about 50% of its weight in water, that in its fully-hydrated state can be stretched by at least about 10% of its original dimension without fracture, and that exhibits a conductivity of at least about 10 -5 S/cm.

Claim 22

Dependent Claim 226 words

A process for preparing a mechanically stable, ion-conducting membrane, comprising the steps of: (a) preparing a polymer solution by combining (i) a copolymer which comprises at least one vinyl aromatic polymer segment chosen from the group: ##STR9## bonded to at least one flexible connecting polymer segment chosen from the group:. ##STR10## and the group; ##STR11## wherein R 1 , R 2 , R 3 and R 4 are chosen independently from the group consisting of hydrogen, phenyl and lower alkyl; R 5 is hydrogen, chlorine or lower alkyl; R 6 is hydrogen or methyl; R 7 is --SO 3 H, --P(O)(OR 8 )OH, --R 9 --SO 3 H or --R 9 --P(O)(OR 8 )OH where R 8 is hydrogen or lower alkyl and R 9 is lower alkylene; Ar is phenyl; and m, n, p and q are zero or integers from 50 to 10,000, with (ii) a sulfonation agent, under controlled reaction conditions, and within a compatible solvent system; (b) removing a portion of the solvents from the polymer solution; and (c) casting the resulting material on a substrate, to form a membrane that absorbs at least about 50% of its weight in water, that in its fully-hydrated state can be stretched by at least about 10% of its original dimension without fracture, and that exhibits a conductivity of at least about 10 -5 S/cm.

Claim 23

Dependent Claim 35 words

A process according to claim 20, wherein the styrene-(ethylene-butylene)-styrene triblock copolymer has a number average molecular weight of about 50,000, and wherein styrene units comprise about 30 to 35 wt % of said triblock copolymer.

Claim 24

Dependent Claim 16 words

A process according to claim 20 wherein said membrane is more than 40 mol % sulfonated.

Claim 25

Dependent Claim 33 words

The process of claim 20, wherein the sulfonation agent is selected from the group consisting of sulfuric acid/acetic anhydride; sulfur trioxide/acetic acid; sulfur trioxide/lauric acid; chlorosulfonic acid/lauric acid; chlorosulfonic acid; and trimethylsilyl-sulfonyl chloride.

Claim 26

Dependent Claim 42 words

A process according to claim 20 wherein said vinyl aromatic polymer segment is selected from the group comprising sulfonic acids of polystyrene and poly(α-methylstyrene) and said flexible connecting polymer segment selected from the group comprising poly(alpha-olefins), polydienes, and hydrogenated derivatives of polydienes.

Claim 27

Dependent Claim 189 words

A process for preparing a mechanically stable, ion-conducting membrane comprising the steps of: (a) adding about a 3-4 wt % solution containing about 3.6 equivalents of styrene-(ethylene-butylene)-styrene triblock copolymer and about 0.4 equivalents of triethylphosphate in about 65/35 dichloroethane/cyclohexane with about 2.0 equivalents of sulfur trioxide in dichloroethane to a solution of about 65/35 dichloroethane/cyclohexane, at a temperature in the range of about -5° to 0° C.; (b) stirring for about 10 to 15 minutes at about -5° to 0° C.; (c) heating at about 80° C. for about 10 to 15 minutes until a purplish color is evident; (d) cooling to less than about 55° C., and then adding a suitable solvent to form a polymer solution; (e) evaporating most of the dichloroethane and cyclohexane at about 40°-50° C. to obtain a viscous liquid; (f) casting the viscous liquid on a substrate to form a membrane that absorbs at least about 50% of its weight in water, that in its fully-hydrated state can be stretched to at least about 100% of its original dimension without fracture, and that exhibits a conductivity of at least about 10 -5 S/cm.

Claim 28

Dependent Claim 189 words

A process for preparing a mechanically stable, ion-conducting membrane comprising the steps of: (a) adding about a 3-4 wt % solution containing about 3.6 equivalents of styrene-(ethylene-butylene)-styrene triblock copolymer and about 0.4 equivalents of triethylphosphate in about 65/35 dichloroethane/cyclohexane with about 2.0 equivalents of sulfur trioxide in dichloroethane to a solution of about 65/35 dichloroethane/cyclohexane, at a temperature in the range of about -5° to 0° C.; (b) stirring for about 10 to 15 minutes at about -5° to 0° C.; (c) heating at about 80° C. for about 10 to 15 minutes until a purplish color is evident; (d) cooling to less than about 55° C., and then adding a suitable solvent to form a polymer solution; (e) evaporating most of the dichloroethane and cyclohexane at about 40°-50° C. to obtain a viscous liquid; (f) casting the viscous liquid on a substrate to form a membrane that absorbs at least about 50% of its weight in water, that in its fully-hydrated state can be stretched to at least about 100% of its original dimension without fracture, and that exhibits a conductivity of at least about 10 -5 S/cm.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-10-20	2001-04-21	2001-10-21	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-10-20	2005-04-21	2005-10-21	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-10-20	2009-04-21	2009-10-21	$7700.00	Window Closed / Lapsed

Fuel cell incorporating novel ion-conducting membrane

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