Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F257/00—Macromolecular compounds obtained by polymerising monomers on to polymers of aromatic monomers as defined in group C08F12/00
  • C08F257/02—Macromolecular compounds obtained by polymerising monomers on to polymers of aromatic monomers as defined in group C08F12/00 on to polymers of styrene or alkyl-substituted styrenes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F259/00—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00
  • C08F259/08—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00 on to polymers containing fluorine
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F279/00—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00
  • C08F279/02—Macromolecular compounds obtained by polymerising monomers on to polymers of monomers having two or more carbon-to-carbon double bonds as defined in group C08F36/00 on to polymers of conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F287/00—Macromolecular compounds obtained by polymerising monomers on to block polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F290/00—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups
  • C08F290/08—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups on to polymers modified by introduction of unsaturated side groups
  • C08F290/12—Polymers provided for in subclasses C08C or C08F
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/06—Oxidation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/42—Introducing metal atoms or metal-containing groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • 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
  • C08G77/42—Block-or graft-polymers containing polysiloxane sequences
  • C08G77/442—Block-or graft-polymers containing polysiloxane sequences containing vinyl polymer sequences
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2666/00—Composition of polymers characterized by a further compound in the blend, being organic macromolecular compounds, natural resins, waxes or and bituminous materials, non-macromolecular organic substances, inorganic substances or characterized by their function in the composition
  • C08L2666/02—Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/003—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/04—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to rubbers

Definitions

• the present invention relates to polymeric materials, in particular to proton-conducting polymers for use in fuel cells.
• 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 be used in improved proton conducting materials, for example, for use in fuel cells.
• Fig. 1 shows the molecular structure of trimethoxysilyl methacrylate
• TSMA TSMA
• Fig. 2 is a schematic representation of an example polymer according to the present invention.
• Novel proton-conductive membranes are prepared that include thermoplastic polymers (including rubbers) that are stable at high temperatures and have excellent mechanical properties.
• thermoplastic polymers including rubbers
• organic polymer chains, or monomers thereof are activated, by attachment of alkoxysilyl groups to the polymer chains through graft- copolymerization.
• Fig. 1 shows the molecular formula of an example compound, methacryloxypropyltrimethoxysilane or trimethoxysilyl methacrylate (TSMA).
• Fig. 2 illustrates a representative structure of a grafted polymer chain, such as the structure of SBS- g-TSMA or PVDF- g-TSMA.
• the thicker line 10 represents a polymer chain
• the line 12 represents a grafted methacrylate backbone
• S represents a silane group such as trimethoxysilyl.
• An activated polymer can be dissolved in certain solvents together with one or more other silanes, allowing copolymerization.
• a polymer (or a monomer or oligomer) including an alkoxysilyl group can be co- polymerized with one or more other silanes, such as alkoxysilanes including tetraethoxysilane (TEOS), and sulfonated phenyltriethoxysilane (SPTEOS), and hydrolyzed by water with acid as a catalyst.
• TEOS tetraethoxysilane
• SPTEOS sulfonated phenyltriethoxysilane
• a polymer including an alkoxysilyl group can be co- polymerized with tetraethoxysilane (TEOS) and/or sulfonated phenyltriethoxysilane (SPTEOS), and hydrolyzed by water with acid as a catalyst.
• TEOS tetraethoxysilane
• SPTEOS sulfonated phenyltriethoxysilane
• other proton conducting components such as H 3 PO 4 , imidazole, benzimidazole, and 2- phenyl imidazole, can be added and further stirred, again typically for several hours.
• the sols can be cast, for example in petri dishes, and heated in dry- oven at 60°C for several days to form gels or cure and evaporate the solvents.
• Polymers which can be introduced into improved proton electrolyte membranes according to this invention include poly(vinylidine fluoride) (PVDF), poly(vinylidine fluoride-hexafluoropropylene) (PVDF-HFP), poly(styrene butadiene) copolymers (SBR), styrene-butadiene-styrene block copolymer (SBS), poly(tetrafluoroethylene-hexafluoropropylene) (PTFE-HFP), poly(bis(trifluoroethoxy)phosphazene), poly(bis(trifluoroethoxy)phosphazene) mixed -substitute polymers (PNF rubber), poly(butadiene) rubber (PBR), poly(3-chlorobutadiene) rubber (PCBR), poly(
• Example grafted polymers include PVDF-HFP-g-MPTEOS (mercaptopropyltriethoxysilane), PVDF-g-VTEOS (vinyl triethoxysilane), and SBS-g-MPMDMOS (methacryloxypropylmethyldimethoxysilane). Polymers can also be grafted with two or more different silane species, for example as in PVDF-HFP-g-MPTEOS/TEOS/SPTEOS (sulfonated phenyltriethoxysilane) or SBS-g-MPMDMOS/TEOS.
• Organosilicon precursors grafted to polymer chains according to this invention can have the following formula: A-R-Si(E 3-x B x ) where A is a functional group, R is a linking group, E is a first substituent group, and B is a second substituent group.
• functional groups include vinyl, acrylate, or methacrylate groups. Functional groups may be polymerizable with each other, or copolymerizable with other components, such as other organosilicon precursors. Other examples of functional groups include hydroxyl (OH), halogen (-X), thiol (-SH), epoxy ring, amines (such as -NH 2 ), and the like, allowing grafting on to a pre-existing polymer.
• linking groups include alkyl chains (such as alkyls from C ⁇ to C 20 ), and other flexible chains. Linking groups may include one or more carbon atoms, double bonds, oxygen atoms, rings (such as phenyl groups) or other atoms, and may be straight or branched.
• first substituent groups include' alkyl groups, such as methyl or ethyl, alkenyl groups, and the like.
• second substituent groups include alkyloxy groups, such as ethoxy or methoxy groups.
• specific examples include (3-acryloxypropyl) dimethylmethoxysilane, (3-acryloxypropyl) methyldimethoxysilane, (3- acryloxypropyl) trimethoxysilane, 3 -(N-allylamino)propyltrimethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, butenyltriethoxysilane, docosenyltriethoxysilane, (methacryloxymethyl)dimethylethoxysilane, methacryloxymethyltriethoxysilane, methacryloxymethyltrimethoxysilane, methacryloxypropyldimethylethoxysilane, methacryloxypropyldimethylmethoxysilane, methacryloxypropylmetliyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, methacryloxypropyltriethoxysilane,
• One example method for grafting an organosilicon to a polymer chains is a radical polymerization, for example one that is initiated by a chemical initiator or UV photografting.
• Conventional polymer grafting techniques known in the polymer chemistry art can be adapted for use in preparing materials according to the present invention.
• compounds according to the present invention are not limited to those prepared by the above mentioned techniques.
• the polymer can be treated by ozone first, and then the ozone-activated polymer provides a co-polymerization reaction with an organosilicon precursor, such as those listed above.
• Other pre- treatments of a suitable treatable polymer include chemical treatment (for example with an initiator), UV or other radiation exposure, and the like.
• a polymer can be provided with functional groups (such as hydroxyl groups, halides, acid groups, and the like), so that silanes or silane-containing sidechains can be grafted to the polymer without the need for any particular polymer pre-treatment.
• functional groups such as hydroxyl groups, halides, acid groups, and the like
• PVDF-HFP-g-MPTEOS Synthesis of PVDF-HFP-g-MPTEOS : A PVDF-HFP powder with an average molecular weight of about 450000 was dissolved in N-methyl-2- pyrrolidone (NMP) with a concentration of 75 g /L. A continuous O 3 /O 2 flow, where the ozone was generated by an ozone generator, was bubbled through in a flow rate of 300 L/H at room temperature. The treatment time can be 20 to 60 minutes to give the ozone content of about 2 x 10 "4 mol per gram of polymer.
• NMP N-methyl-2- pyrrolidone
• the polymer solution was cooled in an ice bath quickly, and the ozone-treated PVDF-HFP polymer was precipitated by excess ethanol, filtered, and dried under reduced pressure at room temperature.
• 1 g of the ozone-treated PVDF-HFP was mixed with the amount of methacryloxypropyltriethoxysilane (MPTEOS) from 1 g to 3 g in 20 ml of MPTEOS.
• MPTEOS methacryloxypropyltriethoxysilane
• PVDF-g-MPTEOS copolymer as precipitate, and remove the homopolymer of MPTEOS. After filtration, the PVDF-HFP-g-MPTEOS copolymer was washed three times with large amounts of ethanol to remove all MPTEOS homopolymer.
• EXAMPLE 2 Synthesis of PVDF-g-VTEOS: The PVDF powders was dissolved in N- methyl-2-pyrrolidone (NMP) with a concentration of 75 g /L. A continuous O 3 /O 2 flow, where the ozone was generated by an ozone generator, was bubbled through in a flow rate of 300 L/H at room temperature.
• NMP N- methyl-2-pyrrolidone
• the treatment time can be 20 to 60 minutes to give an ozone content of about 2 x 10 "4 mol per gram of polymer.
• the polymer solution was cooled in an ice bath quickly, and the ozone-treated PVDF polymer was precipitated by excess ethanol, filtered, and dried under reduced pressure at room temperature. 1 g of the ozone-treated PVDF was mixed with the amount of vinyltrimethoxysilane
• VTEOS VTEOS
• NMP N-methyl methacrylate
• the reactor flask was placed in a thermostated oil bath at 100°C with stirring for 3 hours under the protection of N 2 , and then cooled into an ice bath.
• the mixture of the reaction was treated by an excess ethanol to get the PVDF- g-VTEOS copolymer was precipitate, and remove the homopolymer of VTEOS.
• the PVDF-g-VTEOS copolymer was washed with a large amount of ethanol three times to remove all VTEOS homopolymer.
• SBS-g-MPMDMOS Styrene-Butadiene-Styrene block copolymer
• THF tetrahydrogenfuran
• BPO initiator benzoyl peroxide
• PSB-g-MPTEOS 1 g of Polystyrene butadiene) copolymers (SBR), was dissolved in 20 ml toluene completely by stirring in a three-neck flask with a condenser and a gas line. 1.5 g of methacryloxypropyltriethoxysilane (MPTEOS) and 0.1 g initiator Benzoyl peroxide (BPO, 4 x 10 "4 mol) were added to the solution. The reaction flask was put into oil bath and kept at 80°C for at least 6 hours under the protection of Ar.
• MPTEOS methacryloxypropyltriethoxysilane
• BPO Benzoyl peroxide
• PVDF-HFP-g-MPTEOS copolymer tetraethoxysilane (TEOS) and sulfonated phenyltriethoxysilane (SPTEOS) were dissolved in certain amount of ethyl acetate.
• the weight ratio of PVDF-HFP-g-MPTEOS copolymer to total of TEOS and SPTEOS can be from 20 / 80 to 80 / 20, and that of TEOS to SPTEOS from 10/90 to 90 /10.
• 0.5 N HC1 aqueous solution was added and stirred. The amount of water added can be 4 moles to one mole of total Si in the solution.
• EXAMPLE 6 Manufacture of proton conducting hybrid inorganic-organic membranes: SBS-g-MPMDMOS copolymer and tetraethoxysilane (TEOS) were dissolved in certain amount of THF.
• the weight ratio of SBS-g- MPMDMOS copolymer to TEOS can be from 20 / 80 to 80 / 20.
• 0.5 N HC1 aqueous solution was added to the solution and stirred.
• the amount of water added can be 4 moles to one mole of total Si in the solution. After stirring for 3 hours for complete hydrolysis, H 3 PO 4 85% aqueous solution was added and further stirred for at least 6 hours.
• ACID GROUPS Acid group species can also be attached to the network, for example, inorganic acid groups such as sulfonic acid group (-SO 3 H), phosphoric acid groups (-PO 3 H), boronic acid (-B(OH) ), and the like, and/or organic acid groups such as a carboxylic acid groups (-COOH).
• the dissociable proton may be replaced by another ion, such as an alkali metal ion, other metal ion, ammonium ion, or the like.
• Membranes formed according to the present invention can provide sufficient thermal stability to be used above 120°C, even if the membranes have included acid groups such as -SO 3 H groups.
• Acid-containing silanes can be used in a copolymerization reaction with other compounds described herein.
• Acid containing silanes include silanes such as PETHS (PO(OH) 2 -C2H 4 -Si(OH) 3 , phosphoryl ethyl trihydroxyl silane, and alkyloxy analogs), acid-substituted phenyl trialkyloxy silanes (such as SPS (Si(EtO) 3 -Ph-SO 2 OH), and the like.
• Acid-containing silanes may further include a functional group as discussed above, such as a polymerizable group, and/or a group allowing grafting to an organic polymer chain. Acid-containing silanes may also include organic acid groups, such as carboxylic acid groups. Other species that can be attached to the network include amide groups, such as bissulfonylamide groups.
• APPLICATIONS Proton conducting materials can be used as membranes in fuel cells.
• a fuel cell according to the present invention includes a positive electrode, a negative electrode, and a proton-conducting membrane formed from proton conducting ma described elsewhere. The dimensions of the membrane will be determined by the configuration of the fuel cell, as is well known.
• Proton conducting materials can be produced in a form suitable for use as a membrane without further processing, or formed as a tape or sheet that can be cut to a desired shape, or further processed.
• Proton conducting materials can include or be disposed on one or more reinforcing sheets, such as a web material.
• a thermally stable material for example in the form of a web or grid, may be included within a membrane or on its surface so as to improve the mechanical properties of the membrane.
• aNafion grid may be included to reduce membrane brittleness.
• an example fuel cell according to the present invention includes a positive electrode, a negative electrode, and a membrane therebetween formed from a proton conducting material described herein.
• Proton electrolyte membranes or other forms of the polymer conducting materials described herein can be used in fuel cells, hydrogen separation/purification, reforming/partial oxidation of hydrocarbon fuels, contaminant removal, gas sensing, and other processes relevant to energy storage and conversion.
• Membranes with high proton conductivity but with little or no dependence on humidity in the temperature range from 100 to 200°C are can be used in PEM fuel cells with much higher energy efficiency and tolerance of anode catalyst to carbon monoxide poisoning.
• Proton conducting materials according to the present invention can further include particles such as metal-containing particles (such as nanometer-sized hygroscopic metal oxides), polymers dispersed through the membrane for improved mechanical properties, main-chain polymers having electron lone pair providing atoms within the main chain, acid-group substituted polymers (such as polymers including inorganic acid groups such as -H 3 PO ) and dopants such as proton-conductive inorganic compounds, such as Zr(HPO 4 ) 2 'H 2 O, silicotungstic acid (SiO 2 T2WO 3 ' 26H O), other compounds including acid groups (such as inorganic acids such as -SO 3 H, -PO 3 H 2 ), groups such as -SO NHSO 2 CF 3 , and -
• particles such as metal-containing particles (such as nanometer-sized hygroscopic metal oxides), polymers dispersed through the membrane for improved mechanical properties, main-chain polymers having electron lone pair providing atoms within the main chain,
• organosilanes such as two or more flexibly interconnected silane groups, for example two silane groups interconnected through an alkyl chain having 2 - 20 carbon atoms, can be used in preparation of the membrane, for example to improve mechanical properties.
• bisalkyloxysilyl terminated polymers, oligomers, and/or short organic chains can be used, for example silanes of the form Si(A 3-x B x ) - R - Si(A 3-x B x ), where A can be an alkyloxy group, hydrogen, or other substituent, and B can be an alkyl group, and where R is a flexible chain.
• flexible chains include polypropylene oxide, polytetraethylene oxide, poly(l- butene), polyethylene, polypropylene, polyvinylidene fluoride, polystyrene, polytetrafluoroethylene, polyvinylchloride, and polyvinylalcohol.
• examples include bis(alkyloxysilyl)- terminated polymer compounds.
• flexible chains include straight chain alkyl groups with 2 - 20 carbon atoms, polyethylene oxide (PEO), polypropylene oxide (PPO) and polytetramethylene oxides (PTMO), derivatives thereof, other chains comprising carbon, hydrogen, and optionally oxygen, and other chains.
• Proton conducting materials according to the present invention can further comprise small molecules analogous to the terminal groups discussed above in relation to silane precursors, such as imidazole and its derivatives (including 2- ethyl, 4-methylimidazole and benzimidazole), or other nitrogen-containing heterocycles and their derivatives. Such compounds can be added to improve the proton conductivity of the materials.
• CsHSO 4 cesium hydrogen sulfate
• CsH 2 PO cesium hydrogen phosphate

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
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• 2004
  • 2004-05-28 WO PCT/US2004/016896 patent/WO2005001037A2/en not_active Ceased
  • 2004-05-28 US US10/558,522 patent/US7935735B2/en not_active Expired - Fee Related
  • 2004-05-28 JP JP2006533486A patent/JP4990624B2/ja not_active Expired - Fee Related

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