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  • C08F226/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen
  • C08F226/06—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen by a heterocyclic ring containing nitrogen
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  • C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
  • C07D233/64—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with substituted hydrocarbon radicals attached to ring carbon atoms, e.g. histidine
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  • C07D249/08—1,2,4-Triazoles; Hydrogenated 1,2,4-triazoles
  • C07D249/10—1,2,4-Triazoles; Hydrogenated 1,2,4-triazoles with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
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  • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
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  • C07F7/18—Compounds having one or more C—Si linkages as well as one or more C—O—Si linkages
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  • C08F228/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a bond to sulfur or by a heterocyclic ring containing sulfur
  • C08F228/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a bond to sulfur or by a heterocyclic ring containing sulfur by a bond to sulfur
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  • C08G75/00—Macromolecular compounds obtained by reactions forming a linkage containing sulfur with or without nitrogen, oxygen, or carbon in the main chain of the macromolecule
  • C08G75/20—Polysulfones
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  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/22—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen
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  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/20—Manufacture of shaped structures of ion-exchange resins
  • C08J5/22—Films, membranes or diaphragms
  • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
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  • C08L81/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing sulfur with or without nitrogen, oxygen or carbon only; Compositions of polysulfones; Compositions of derivatives of such polymers
  • C08L81/06—Polysulfones; Polyethersulfones
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
  • H01M8/1018—Polymeric electrolyte materials
  • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
  • H01M8/1027—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having carbon, oxygen and other atoms, e.g. sulfonated polyethersulfones [S-PES]
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
  • H01M8/1018—Polymeric electrolyte materials
  • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
  • H01M8/103—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having nitrogen, e.g. sulfonated polybenzimidazoles [S-PBI], polybenzimidazoles with phosphoric acid, sulfonated polyamides [S-PA] or sulfonated polyphosphazenes [S-PPh]
• • H—ELECTRICITY
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  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
  • H01M8/1018—Polymeric electrolyte materials
  • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
  • H01M8/1032—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having sulfur, e.g. sulfonated-polyethersulfones [S-PES]
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  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
  • H01M8/1018—Polymeric electrolyte materials
  • H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
  • H01M8/1037—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having silicon, e.g. sulfonated crosslinked polydimethylsiloxanes
• • H—ELECTRICITY
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  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
  • H01M8/1018—Polymeric electrolyte materials
  • H01M8/1039—Polymeric electrolyte materials halogenated, e.g. sulfonated polyvinylidene fluorides
• • H—ELECTRICITY
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  • H01M8/10—Fuel cells with solid electrolytes
  • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
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  • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
  • C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
  • C08J2379/06—Polyhydrazides; Polytriazoles; Polyamino-triazoles; Polyoxadiazoles
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  • H01M2300/0065—Solid electrolytes
  • H01M2300/0082—Organic polymers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells

Definitions

• the present invention relates to heterocycle containing compounds, including polymers.
• PEMs Proton electrolyte membranes
• the widely used perfluorosulfonic polymers (mainly Nafion ® ) have serious disadvantages, such as low proton conductivity over 100°C due to loss of water, large amount of fuel crossover, dimensional changes with water contents, high cost, and the reduction of-S0 3 H groups under fuel cell working conditions.
• polybenzimidazole (PBI)-H 3 P0 4 membranes have the best performance.
• PBI-H 3 P0 4 membranes have high proton conductivity above 150°C, good mechanical properties and high thermal stability (J. Electrochem. Soc. 1995, Vol. 142, p.L121).
• H 3 P0 4 can leach out easily from such pure organic polymer membranes, especially when H P0 4 content is high. Meanwhile, when the content of H P0 4 is too high, the mechanical properties are degraded.
• Polyvinazene-H 3 P0 4 was reported to have high proton conductivity from 150°C to 200°C, but the decomposition of -CN groups under acidic conditions limits its application as the electrolyte material in fuel cells (Abstract of ECS meeting, Orlando, FL, USA, October, 2003).
• the heterocycle is a fluorinated imidazole ring.
• the heterocycle is chosen to have a low value of pKa, and may be a triazole ring, other nitrogen-containing heterocycle, or derivative thereof. Good proton conductivity was observed, and PEMs fabricated with such materials can be used in fuel cells and other ion-conducting applications.
• FIGURE 1 shows the proton conductivity of poly(4-vinyl-lH-l,2,3-triazole) in dry air from room temperature to 120°C, compared with poly(4-vinyl-lH-imidazole);
• FIGURE 2 shows proton conductivity of s-PSU doped with lH-l,2,3-triazole in the anhydrous state;
• FIGURE 3 shows ionic conductivities of lH-l,2,4-triazole (4Tri) and that compound intercalated into sulfonated polysulfone polymers, where n is the mole ratio of triazole-ring / -SO 3 H;
• FIGURE 4 shows proton conductivity of the mixtures of immobilized 1H- 1,2,4-triazole (4TriC4) and large molecule acid C ⁇ 2 PhS0 3 H in the anhydrous state;
• FIGURE 5 shows the conductivity ratio of the acid-triazole mixture to the pure lH-l,2,3-triazole ( ⁇ t ⁇ azoie+acid/ ⁇ triazoie) against the concentration ratio of acid to the triazole ( Cacjd/Ct ⁇ azoie x 100);
• FIGURE 6 shows proton conductivity of membranes x MDSPPO-y TEOS -z Si4Tri-m H 3 P0 in anhydrous state
• FIGURE 7 shows proton conductivity of membranes grafted with acid groups (-SO3H) and heterocycle rings at a relative humidity 25% at 80°C.
• Polymers including hybrid inorganic-organic copolymers, and polymer precursors are described, which can be used in proton-exchange membranes (PEMs) having improved proton conductivity.
• PEMs proton-exchange membranes
• the term 'polymer' is used to refer generally to polymers and co-polymers.
• the term 'polymer' can also refer to hybrid inorganic-organic polymers, such as an organically modified silica.
• the term 'grafted', as in heterocycle-grafted polymer, refers to groups attached to a polymer backbone, and is not limited to materials obtained by any specific synthetic method.
• a polymer precursor can be polymerized, or copolymerized with other precursors.
• the abbreviation PEM refers to proton-exchange membranes, also known as polymer electrolyte membranes. These membranes are commonly used as proton- conducting materials in fuel cells. Polymers and other compounds according to the present invention can be used in improved PEMs.
• a PEM may also include other materials chosen to improve mechanical, electrical, or other properties.
• a compound according to the present invention has a general structure
• X-Y-Z where X includes a heterocycle, Y is a linking group, and Z is a polymerizable group, other functional group, or a polymer backbone.
• the linking group Y may include an alkyl chain having two or more carbon atoms.
• the group Z can be a polymerizable group, such as a vinyl group, epoxy group, or hydrolyzable silicon-containing group.
• Z may comprise a polymer, such as an organic polymer backbone, or polymer network such as a hybrid inorganic-organic matrix.
• the heterocycle-including group X may include a nitrogen-containing heterocycle, such as imidazole, pyrazole, pyrazine, pyridine, 1,2,4-triazole, 1,2,3- triazole, pyrimidine, or derivative thereof.
• the group X may further include one or more electron-withdrawing groups attached to a heterocycle. Electron-withdrawing groups are well known in the chemical arts, and not all such groups are mentioned here.
• electron-withdrawing groups include a fluorine atom, a fluorine- containing group (such as fluoroalkyl groups, such as trifluoromethyl, other perfluoroalkyl groups, other groups including -CF 2 -, -CHF-, -CHF 2 , -CH 2 F, and the like), other halogen atom (such as chlorine), other halogenated group (such as - CC1F 2 ) , or other electron-withdrawing group such as -S0 2 , -N0 2 , and -CN.
• a heterocycle can be a nitrogen-containing heterocycle having one or more electron-withdrawing groups as a substituent group.
• he group X can include a heterocycle having at least one atom providing a lone pair of electrons, such as N, O, or S. Heterocycles may include one or more nitrogen atoms, or some combination of N, O, and/or S.
• the X group may include one or more ring structures, which may or may not be fused, and one or more substituents on the ring structure(s).
• the group X may be a heterocycle having a pKa of less than 7, such as less than approximately 5, for example less than approximately 3.
• pKa -log(Ka)
• Ka is defined as the equilibrium constant of the self-dissociation of a protonated heterocycle, and all pKa values cited in this invention were measured in water at 25 °C.
• X may include a fluorinated imidazole ring having a pKa of less than approximately 3, such as 2-fluoro-l-H-imidazole.
• a heterocycle may be an example of the X group discussed above.
• an improved PEM polymer electrolyte membrane
• a polymer having a nitrogen-containing heterocycle attached to a polymer through a linking group the nitrogen-containing heterocycle having a pKa of less than approximately 3, such as less than 2.6.
• an improved PEM is a proton-conducting composite comprising an acid-group containing polymer and a compound having a first heterocycle flexibly interconnected to a second heterocycle by a linking group.
• the heterocycles may be the same or different, and at least one heterocycle may be a nitrogen-containing heterocycle.
• the compound may have at least two nitrogen-containing heterocycles interconnected by one or more organic groups, such as alkyl groups or other flexible chain.
• the acid-group containing polymer can be a sulfonated polymer, such as NafionTM.
• the linking group may be a chain formed by between 5 and 20 atoms, such as an al?kyl chain.
• imidazole rings were fluorinated to synthesize new polymers (including hybrid inorganic-organic copolymers) with fluorinated-imidazole-terminated side chains.
• the fluorination of imidazole rings increases the activity of the protons on imidazole rings.
• the pKa value of imidazole is 6.99, but that of 2-fluoro-l-H-imidazole is 2.44.
• Proton electrolyte membranes (PEM) based on these polymers (including copolymers) and acid groups (in free form or attached on the polymer backbones) exhibit high proton conductivity, excellent mechanical properties, and high thermal stability.
• heterocycles and substituted heterocycles are described which provide low pKa values, and which can act as solvents for protons or proton donors (such as water and/or phosphoric acid) or other proton conducting groups in improved polymer membranes.
• new polymers such as hybrid inorganic- organic copolymers, or composites, include heterocycle groups with suitable pKa values.
• Example heterocycles include one or more nitrogen atoms, and are associated with a low pKa value.
• the ring structure may be an aromatic ring.
• lH-l,2,3-triazole (or the isomer 2H-l,2,3-triazole) and its organic derivatives as illustrated in Scheme 1, have a lower pKa value than imidazole, and are more stable under oxidation conditions than imidazole, so they can act as effective proton conducting groups in the materials.
• Derivatives of a nitrogen- containing heterocycle include heterocycles with one or more organic substituents, such as discussed in the examples below.
• imidazole ring can be readily oxidized under typical fuel cell operating conditions. Also, imidazole and the oxidized product tend to absorb on a Pt electrode to block the active sites for electrochemical reactions, often leading poisoning of the
• an example improved polymer or polymer precursor includes a heterocycle, such as a nitrogen-containing heterocycle, having a pKa of less than approximately 3, for example equal or less than approximately 2.6 (e.g. pyrazole).
• Scheme 1 (1-1 and 1-2) above show possible structures for example heterocycle-containing compounds which may be incorporated into a polymer or copolymer according to the present invention.
• Scheme 1-1 represents 1H- 1,2,3, triazole and derivatives thereof
• Scheme 1-2 represents 2H-l,2,3-triazole and derivatives thereof.
• R group(s) can be on C4 and or C5 of the ring.
• the R group may include groups such as (but not limited to) hydrogen, halogen, alkyl, alkenyl, aromatic group, alkoxyl, ester, sulfone, ketone, thio, thiol, amino, silyl, or other flexible chain and/or functional groups (such as polymerizable groups).
• R may be a linking group attached to a polymer backbone.
• a molecular structure such as shown in Scheme 1 can be grafted onto a polymer.
• a precursor may have a structure represented by Scheme 1, and included in a polymer network by polymerization or co-polymerization.
• An R group may include a functional group which may be polymerized, co-polymerized, or allow addition to an existing polymer network.
• substituent groups may be present, which may be the same or different.
• one substituent may be a halogen
• the other substituent can be a linking group
• one substituent may be a halogen-containing alkyl group
• the other two may be linking groups which include functional groups for polymerization.
• R may be a linking group, such as an organic chain, such as a hydrocarbon chain, linking the heterocycle to a polymer chain, or to a hybrid organic- inorganic matrix.
• R may also link the heterocycle to one or more other heterocycles (which can be the same or different).
• R may be, or include, substituents chosen to modify pKa of the heterocycle.
• Polymer electrolyte membranes based on polymers or copolymers including these heterocycles (as free molecules, as immobilized molecules, or being grafted on the polymer or copolymer backbones through an organic chain), exhibit high proton conductivity, excellent mechanical properties, and high thermal stability.
• Heterocycles (such as those with low pKa values) can be substantially immobilized (for example within a PEM) by linking two or more heterocycle rings together through a soft (flexible) organic chain, as shown in Schemes 2-1 and 2-2.
• the immobilized heterocycles can be dispersed in a sulfonated or phosphonated polymer or copolymer matrix. In addition, they can be mixed with inorganic or organic acids to obtain highly proton conducting materials.
• R- (Htc) n Scheme 2-1
• Htc is a heterocycle; n>l; and R is an organic chain, for example a chain including CH 2 , -C 6 H 4 , CF 2 , CHF, O, and/or S, and the like, as groups or elements).
• Scheme 3 below (3-1 - 3-4) illustrate general structures of heterocycle grafted polymers and copolymers according to the present invention.
• Htc represents a heterocycle
• Ri and ?R 4 may be linear organic chains with Ci to C 20
• R 2 and R 3 may be organic compound units
• Ai can be an acidic group
• m and n are the numbers of the units in the polymer or copolymer.
• R groups may be the same or different.
• Polymers (including copolymers) with grafted heterocycles include polymers having the general structures shown in Scheme 3 (3-1 to 3-4).
• a polymer backbone includes at least one heterocycle, and may comprise a repeated unit including one or more heterocycles.
• (a) polymers according to the present invention can have added (for example', by absorption) acids, including, but not limited to, H 3 P0 4 , H 2 S0 , CF 3 S0 2 NHS0 2 CF 3 , CF 3 S0 3 H, CH 3 S0 3 H, CF 3 P0 3 H 2 , and/or other acids;
• acids including, but not limited to, H 3 P0 4 , H 2 S0 , CF 3 S0 2 NHS0 2 CF 3 , CF 3 S0 3 H, CH 3 S0 3 H, CF 3 P0 3 H 2 , and/or other acids;
• polymers according to the present invention can be mixed with sulfonated, phosphonated, or other acid-group containing proton conducting polymers or copolymers.
• Sulfonated polymers or copolymers include, but are not limited to, poly(styrene sulfonic acid), sulfonated polyetheretherketone (S-PEEK), perfluorosulfonic acid, and sulfonated polyphenylene sulfide (S-PPS).
• Composites may be formed comprising any polymer according to the present invention.
• Htc is a heterocycle
• Ri. can be a linear organic chain with to C 20
• R 2 , R and R 6 can be an organic group with Ci to C 20
• R 3 and R 5 can be an organic compound with saturated linear or branched chain
• A can be an acidic group.
• Example compounds can include one or more species of heterocycle ring grafted onto hybrid inorganic-organic polymer backbones.
• Several possible structure types of the hybrid inorganic-organic copolymers are represented by Scheme 4. Acid groups, such as inorganic acid groups, may also be attached to a polymer backbone.
• Hybrid inorganic-organic copolymers with heterocycle-terminated organic side chains were synthesized by hydrolysis of corresponding heterocycle-grafted alkoxysilanes in certain solvents, such as methanol, ethanol, and THF, together with other alkoxysilanes and precursors as organic chain formers by water with hydrochloric acid as catalyst.
• solvents such as methanol, ethanol, and THF
• the membrane manufacture process has been described in our former invention disclosures or patent applications, incorporated herein by reference, for example U.S. Prov. Pat. App. Ser. No. 60/439,985, filed Jan. 14, 2003.
• imidazole rings were fluorinated to provide new polymers or hybrid inorganic-organic copolymers with fluorinated-imidazole-terminated side chains.
• Halogenation of imidazole rings can increase the activity of the protons on imidazole rings, increasing proton conductivity.
• Proton electrolyte membranes (PEM) fabricated using polymers according to the present invention incorporating fluorinated imidazole rings and inorganic acid groups (as free acid molecules, or acid groups attached to a polymer backbones) exhibit high proton conductivity, excellent mechanical properties, and high thermal stability.
• Scheme 5 (5-1 and 5-2) illustrates examples of such fluorinated-imidazole ring grafted polymers.
• Ai and A 2 can be -H, -F, -CF 3 , or -C 2 F 5 groups, where at least one of Ai and A 2 is F or a fluorine containing group);
• Ri . and R 4 can be linear organic chains with CI to C20 (1-20 carbon atoms);
• R 2 and R 3 are organic compound units;
• a 3 is an acidic group; and
• m and n are the numbers of the units in the polymer or copolymers.
• the polymers can absorb acids, including, but not limited to, H 3 P0 4 , HS0 4 , CF 3 S0 2 NHS0 2 CF 3 , CF 3 SO 3 H, CH 3 SO 3 H, CF 3 PO3H2, and others. Acids can be attached to the polymer backbone, or included as free acid molecules, absorbed into a polymer membrane, or a composite formed with an acid-group containing polymer or other compound.
• Ai and A 2 can be -H, -F, -CF 3 , -C F 5 group, or similar, where at least one of Ai and A 2 is -F or a fluorine-containing group;
• Ri can be a linear organic chain with CI to C20 (1 -20 carbon atoms);
• R 2 , R 4 and R 6 are organic groups with Ci to C 20 ;
• R 3 and R 5 are organic groups with saturated linear or branched chains; and
• a 3 is an acidic group.
• Organic groups may be the same or different.
• Scheme 6 (6-1 to 6-4) shows several possible general structure types for hybrid inorganic-organic copolymers according to the present invention.
• the hybrid inorganic-organic copolymers with fluorinated-imidazole-ring-terminated organic side chains were synthesized by hydrolysis of corresponding fluorinated-imidazole- grafted alkoxysilanes in certain solvents, such as methanol, ethanol, and THF, together with other alkoxysilanes and precursors as organic chain formers by water with hydrochloric acid as catalyst.
• solvents such as methanol, ethanol, and THF
• these polymers or copolymers shown in Scheme 6 can absorb acids, including, but not limited to, H 3 P0 4 , HS0 4 , CF 3 S0 2 ?NHSO 2 CF 3 , CF 3 S0 3 H, CH 3 S0 3 H, CF 3 P0 3 H 2 , and others.
• Such precursors include: 2-(but-3-enyl)-5-fluoro-lH-imidazole, 5-fluoro-4-(2-(oxiran-2-yl)ethyl)-lH-imidazole, 5-fluoro-4-(2,2,3,4,4-pentafluorobut- 3-enyl)-lH-imidazole.
• C 2 F 5 groups where at least one of Ai and A 2 is -F or a fluorine-containing group; Ri, R 2 is a linear organic chain with to C 20 (1 - 20 carbon atoms); and B, Bi, and B 2 is a functional group (such as a polymerizable group).
• the precursors were synthesized from lH-imidazole-4-chloromethyl-5-fluoro- ethyl ester or lH-imidazole-4-chloromethyl-2,5-fluoro-ethyl ester which were synthesized from lH-imidazole-4-carboxylic-5-amino-ethyl ester.
• chemicals were obtained from the Zelinsky Institute. The synthesis method was described in J. Am. Chem. Soc. 95(14), 4619-24, 1973, and in J. Org. Chem. 49(ll),1951-54, 1984.
• Several specific exemplary precursors were synthesized as follows.
• Heterocycle-containing precursors useful for preparation of polymers or copolymers, can include a linear organic chain with Ci to C 2 o, and a functional group for polymerization.
• Such precursors include: 5- fluoro-3 -vinyl- lH-pyrazole, 4-(allyloxy)-2,3,5,6-tetrafluoropyridine, 4-(but-3-enyl)-2- fluoropyridine, 2-(but-3-enyl)pyrazine, 2-(but-3-enyl)-6-fluoropyrazine, 2-(allylthio)- 4-fluoropyrimidine, 2-(allylthio)pyrimidine, l-allyl-l ⁇ -[l,2,3]triazole.
• Methyltriphenylphosphonium bromide 6 mmol was dissolved in anhydrous THF 10 ml. Under nitrogen gas, at 0°C, n-butyl lithium (2M in cyclohexane) 3.5 ml was added into the solution and the mixture was stined for lh at room temperature. 4.6 mmol l-(4-methoxybenzyl)-lH-l,2,3-triazole-4-carbaldehyde in 5 ml THF was added into the solution and stined overnight.
• Heterocycle-containing precursors which may be used in the preparation hybrid inorganic-organic copolymers are shown in Scheme 7. Specific examples include: 2-(3-(trimethoxysilyl)propylthio)- pyrimidine, 2-(3-
• Ri can be a linear organic chain with Ci to C 20 ;
• M can be alkoxy, such as C 2 H 5 0- or CH 3 O-;
• A can be alkyl, such as C 2 H 5 - or CH 3 -;
• X is 1,2, or 3; and
• the precursors were synthesized from lH-imidazole-4-chloromethyl, 5- fluoro-ethyl ester or lH-imidazole-4-chloromethyl, 2,5-fluoro-ethyl ester.
• Several specific exemplary precursors were synthesized as follows.
• Figure 1 shows the proton conductivity of poly(4-vinyl-lH-l,2,3-triazole) in dir air from room temperature to 120°C , compared with poly(4-vinyl-lH-imidazole) from Solid State Ion. 138, 259-265 (2001).
• E5CAMPLE 28 Synthesis of poly (5-(4-vinylbenzylthio)-lH-l,2,3-triazole), Scheme 43.
• Sulfonated polysulfone s-PSU
• 1H-1,2,3- triazole Composite membranes of sulfonated polysulfone (s-PSU) and 1H-1,2,3- triazole.
• Sulfonated polysulfone sPSU
• the sPSU was dried in the oven at 120°C for two weeks over P 2 0 5 and then kept in a desiccator.
• Ion-Exchange Capacity (IEC) of sPSU was determined by IH NMR and back titration.
• the sPSU polymers (IEC of 1.40 mequiv/g) were immersed into various amount of liquid IH- 1,2,3 -triazole at 90°C, which readily intercalated into the polymer thus producing homogeneous membranes.
• Figure 2 shows proton conductivity of s-PSU doped with lH-l,2,3-triazole in anhydrous state. Proton conductivity of the materials is 0.01 S/cm at 120°C and 10 "4 S/cm at room temperature.
• the sPSU polymers (IEC of 1.40 mequiv/g) were mixed into various amount of liquid lH-l,2,4-triazole at 120 °C, which readily intercalated into the polymer thus producing homogeneous membranes.
• the ratio n [lH-l,2,4-triazole]/[-S0 3 H] was calculated.
• Figure 3 shows proton conductivity of s-PSU doped with lH-l,2,4-triazole in anhydrous state. Proton conductivity of the materials is 5 x 10 "3 S/cm at 140°C and 1.5 x lO "3 S/cm at lOO°C.
• Figure 5 shows the conductivity ratio of the acid-triazole mixture to the pure lH-l,2,3-triazole ( ⁇ tr iazoie+acid/ ⁇ triazoie) against the concentration ratio of acid to the triazole ( Cacid Ctriazoie x 100).
• the highest conductivity of acid- triazole mixture is about 0.015 S/cm at room temperature under anhydrous condition.
• Hybrid inorganic-organic copolymer membranes with grafted 1 H- 1,2,4- triazole and phosphonic acid 3-(4-(2-(trimethoxysilyl)ethyl)benzylthio)-lH-l,2,4-triazole (Si4Tri), Bis((3- methyldimethoxysilyl)propyl)polypropylene oxide (MDSPPO), and tetraethoxysilane (TEOS) were dissolved in ethanol by stirring. 0.5 N HC1 aqueous solution was added dropwise to the mixture, stined for 24 hours, and then H 3 P0 4 solution of ethanol was added dropwise with further stining for 6 hours. The sols were cast on petri dishes. The amount of water added was 4 times of the total Si in mole.
• the membranes were dried at 60°C for 3 days, at 80°C for 3 hours, and then at 100 °C for 1 hour to evaporate the organic solvents and water.
• the samples were labeled by their mole composition as x MDSPPO-y TEOS -z Si4Tri-m H 3 P0 4 , where x, y, and z represent the moles of Si from MDSPPO, TEOS, and Si4Tri, an m is the moles of H P0 4 , respectively.
• the value of x is 1-2, y 2-4, z 3-6, and m 3-8.
• the proton conductivity varied from 10 "7 S/cm to 10 "2 S/cm from room temperature to 150°C in anhydrous state.
• EXAMPLE 34 Hybrid inorganic-organic copolymer membranes with pyrimidine terminated side chain and -SO 3 H group terminated side chain: 3 -(trihydroxysilyl)-l -propane sulfonic acid (S), 2-(4-(2-(trimethoxysilyl)ethyl)benzylthio)pyrimidine (SiPy), Bis((3- methyldimethoxysilyl)propyl)polypropylene oxide (M), and bis(triethoxysilyl)octane (Oc) were dissolved in ethanol by stirring. 0.5 N HCl aqueous solution was added dropwise to the mixture, and further stined for 6 hours. At last the sols were cast on petri dishes. The water amount added is 4 times of the total Si in mole.
• the membranes were dried at 60°C for 3 days, at 80°C for 3 hours, and then at 100 °C for 1 hour to evaporate the organic solvents and water.
• the samples were labeled by their mole composition as x M-y Oc -z SiPy-m S, where x, y, z, and m represent the moles of Si from M, Oc, PPr, and S, respectively.
• the value of x is 2-4, y 1-2, z 2-6, and m 2-6.
• These membranes are thermally stable up to 240°C in dry air.
• the proton conductivity varied from 10 "7 S/cm to 10 "1 S/cm from room temperature to 160 °C in varying relative humidity.
• Hybrid inorganic-organic copolymer membranes with lH-l,2,3-triazole terminated side chain and -SO 3 H group terminated side chain 3-(trihydroxysilyl)-l- propane sulfonic acid (S), 5-(4-(2-(trimethoxysilyl)ethyl)benzylthio)-lH-l,2,3- triazole (Si3Tri), bis((3-methyldimethoxysilyl)propyl)polypropylene oxide (M), and bis(triethoxysilyl)octane (Oc) were dissolved in ethanol by stirring.
• S 3-(trihydroxysilyl)-l- propane sulfonic acid
• Si3Tri 5-(4-(2-(trimethoxysilyl)ethyl)benzylthio)-lH-l,2,3- triazole
• M bis(3-methyldimethoxysilyl)propyl)polypropylene oxide
• the water amount added was 4 times of the total Si in mole.
• T The membranes were dried at 60°C for 3 days, at 80°C for 3 hours, and then at 100°C for 1 hour to evaporate the organic solvents and water.
• the samples were labeled by their mole composition as x M-y Oc -z SiFP-m S, where x, y, z, and m represent the moles of Si from M, Oc, SiFP, and S, respectively.
• the value of x is 2-4, y is 1-2, z is 2-6, and m is 2-6.
• These membranes are thermally stable up to 240 °C in dry air.
• the proton conductivity varied from 10 "7 S/cm to 10 "1 S/cm from room temperature to 160°C in low relative humidity.
• Example compounds according to the present invention include heterocycles, such as nitrogen containing heterocycles.
• Heterocycles can be 5- or 6- membered single ring structures, larger ring structures, multiple ring structures, or some other ring structure, and each heterocycle may include, for example, 1, 2, 3, or more nitrogen atoms. In other examples, one or more other atoms providing a lone pair of electrons may be included in a ring structure.
• New thermally stable heterocycle containing compounds can replace water in a polymer electrolyte membrane fuel cell (PEM FC) system, allowing higher operation temperature.
• PEM FC polymer electrolyte membrane fuel cell
• an improved PEM comprises a polymer membrane, an acid group, and a compound including two or more nitrogen-containing heterocycles interconnected by organic chains.
• the acid group may be part of a free acid molecule, or be bound to the polymer membrane.
• the polymer membrane may include a polymer according to the present invention, a polymer according to one of our co- pending applications, or a polymer known in the art, such as NafionTM.
• nitrogen-containing heterocycles include pyrazine, pyrazole, pyridazine, pyridine, pyrimidine, and pyrrole, and fused ring structures such as pynolizine, quinazoline, quinoline, quinolizine, quinoxaline, phenanthroline, phenazine, cinnoline, phthalazine, and the like.
• pynolizine quinazoline, quinoline, quinolizine, quinoxaline, phenanthroline, phenazine, cinnoline, phthalazine, and the like.
• Nitrogen-containing heterocycles may further include oxygen, sulfur, selenium, other chalcogenides, or other non-carbon elements within a ring structure.
• Nitrogen containing heterocycles may be halogenated, for example fluorinated.
• Heterocycles may be nitrogen-containing, oxygen-containing, or sulfur-containing.
• Compounds according to the present invention may include heterocycles, the heterocycles including one or more non-carbon atoms such as nitrogen, oxygen, sulfur and/or other non-carbon atoms.
• Heterocycles may be aromatic or non-aromatic, though aromatic heterocycles are prefened.
• Heterocycles may be halogenated, for example, fluorinated. Other substituents are discussed below.
• Heterocycles may be substituted in one or more substitutable positions, for example with a group selected from: hydroxy, amino, hydrogen, halogen (chloro-, fluoro-, iodo-, bromo-), methyl or other alkyl, aromatic, alkenyl, methoxy or other alkoxy, nitro, nitrobenzyl or other aromatic derivative, ester, sulfone, ketone, thio, thiol, amyl, allyl, allylthio, allyloxy, cyano, silyl, or other group or combination of groups. If there is more than one substituent, the substituents may be the same or different. Substituents may be chosen so as to lower pKa.
• Example compounds according to the present invention include a nitrogen containing heterocycle having a pKa of equal to or less than 7 (conesponding to imidazole), for example having a pKa of equal to or less than approximately 5.2 (conesponding to pyridine), for example, a pKa equal to or less than approximately 2.4 (conesponding to lH-l,2,4-triazole), for example, a pKa equal to or less than approximately 1.2 (conesponding to lH-l,2,3-triazole).
• Tables of pKa for various heterocycles are ?known in the chemical art, and will not be reproduced here.
• the pKa used may be for the heterocycle ring structure alone, or for a molecule or analogous moiety containing the heterocycle (for example, a polymer side chain).
• a heterocycle pKa is chosen so as to be equal to or less than the approximate pH of the PEM environment.
• Example polymers according to the present invention may further include inorganic acid groups bound to a polymer backbone, and/or other proton solvent groups such as imidazole and derivatives thereof, such as fluorinated imidazole, for example as described in our co-pending patent applications.
• Example PEMs according to the present invention may further include free acid molecules, water, insoluble inorganic acid salts, and the like to enhance proton conductivity, for example as described in our co-pending applications.
• Acid groups for example as part of free acid molecules or acid groups attached to a polymer backbone, are known in the chemical arts and further discussed in our co-pending applications.
• PEMs at least in part including (or synthesized using) compounds disclosed herein.
• PEMs including polymers discussed here provide high proton conductivity in a dry atmosphere and at higher temperatures; good mechanical properties; and high thermal stability.
• PCT/US2004/ 016896 and PCT/US2004/016897 are incorporated herein in their entirety.

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