Patent Application
20170114196
Multi-use membranes (use as AEM, H3PO4-doped HT membranes, HT-HyS electrolysis membranes, membranes as separators for redox-flow batteries)
mixing a halomethylated polymer with a basic polymer (eg PBI: F6PBI or PBIOO) in a dipolar aprotic solvent such as DMSO or DMAc, NMP, etc.
Covalent crosslinking by heating to 80-180° C. for 2-24 hours (1- or 2-sided imidazolization)
Optional subsequent sulfonation of the polymer films by incorporation in 60-90% H2SO4 at T=25-180° C. for 0.5-24 hours (see sulfuric acid-treated HyS electrolysis membranes)→both ionically and covalently crosslinked blend membranes are obtained)
Blending a partially phosphonated polymer (neutralized with an amine) with a PBI (preferably PBIOO, ABPBI, F6PBI or Celazol® Hozol®), adding a bisphenol or bisthiophenol (e.g., 4,4′-diphenol or TBBT and others), Addition of an amine until bis(thio)phenol is completely neutralized (color change of the solution), doctoring the solution and evaporating the solvent at 90-170° C., followed by 1-24 hours of heating at 100-200° C. for covalent crosslinking of F by thiolate or phenolate groups (nucleophilic substitution)
Mixing a halomethylated polymer with a PBI (preferably ABPBI, F6PBI or PBIOO) in DMAc, cooling to 0-5° C., admixing any tertiary amine (eg TEA, DABCO, ABCO), rapid homogenization and doctoring, evaporation at 60-150° C., post-treatment in sulfuric acid (60-90% H2SO4), washing of the film→covalent-ionically cross-linked acid-base blend membrane
Mixing of a halomethylated polymer with a PBI (F6PBI or PBIOO) in DMAc, cooling to 0-5° C., addition of an amine (eg TEA, DABCO, ABCO) and a diiodoalkane, rapid homogenization and doctoring, evaporation at 90°−130° C., post-treatment in sulfuric acid (60-90% H2SO4), washing of the film→covalent-ionically cross-linked acid base blend membrane
mixing a halomethylated polymer with a PBI (F6PBI or PBIOO) in DMAc, cooling to 0-5° C., adding a sulfonated polymer and a monoamine (NMM), rapid homogenization and knife coating or casting, evaporation at 80-150° C., aftertreatment in diamine (TMEDA, DABCO) or in monoamine (NMM) at RT-100° C., washing of the film→Covalent-ionically cross-linked acid base blend membranes.
Mixing a halomethylated polymer with a PBI (F6PBI or PBIOO) in DMAc, cooling to 0-5° C., adding (sulfonated polymer and) an N-alkylated or arylated benz)imidazole (Melm or EtMelm), rapid homogenization and doctoring or casting, evaporation at 80-150° C., washing the film→Covalent-ionically cross-linked acid-base blends.
Phosphoric acid-doped polybenzimidazole (PBI) for use in fuel cells is based on the work of Savinell et al1. The advantage of the PBI/H3PO4 composite membranes is that the phosphoric acid takes over the H+-conduction instead of water2, which makes it possible to apply this type of membrane at fuel cell operating temperatures between 100 and 200° C. The disadvantage of this type of membrane is the possible bleeding out of the phosphoric acid from the composite membrane as the fuel cell temperature falls below 100° C. and condensing product water floats phosphoric acid molecules out of the membrane3. The liberated phosphoric acid can then cause severe corrosion damage in the fuel cell system. A further disadvantage of H3PO4-doped PBI membranes is the chemical degradation of the PBI in the fuel cell4. Several strategies have been implemented in the R & D of this type of membrane to reduce the degradation of PBI in fuel cell operation. One strategy is the preparation of acid-base blend membranes from PBI and acidic polymers, whereby the acidic polymer takes over the task of an ionic crosslinker by proton transfer from the acidic polymer to the PBI-imidazole. Acid base blend membranes have been researched and developed in the working group of the inventors5 and partly modified in cooperation with the working group of Q. Li at the Danish Technical University (DTU) for medium temperature membranes within the framework of an EU project. It was found that the base-excess acid-base blend membranes exhibited better chemical stability than pure PBI, which can be attributed to the ionic crosslinking sites in the blend membranes6. In the working group, base-acid blend membranes were prepared from different PBIs such as PBIOO and F6PBI with phosphonated poly(pentafluorstyrene)7 and doped with H3PO48. The membranes (blend membrane of 50% by weight of PBIOO and 50% by weight of PWN) showed a mass loss of only 2% after 144 hours in Fenton's reagent, whereas pure PBIOO had a mass loss of 8% after the same storage period in Fenton's reagent. Another way to increase the chemical stability of PBI-type membranes is the preparation of covalently cross-linked PBI membranes described by Q. Li et al. and other research groups. The PBI can be crosslinked with a low molecular weight crosslinker, for example bisphenol A bisepoxide9, divinyl sulfone10 or a high molecular weight crosslinker, such as chloromethylated PSU11 or bromomethylated polyether ketone12. Further attempts to increase the stability of PBI membranes include the preparation of PBI membranes modified with nanoparticles13, or the preparation of partially sulfonated PBI, which is cross-linked intra- or intermolecularly by proton transfer from the acidic group to the imidazole group14,15. It has also already been reported that PBI is grafted onto the side chain containing phosphonic acid groups, forming ionic crosslinking sites between the basic PBI main chain and the acid side chains16,17. Of the PBI membranes of the prior art, the blended membranes of PBI and poly (2,3,5,6-tetrafluorstyrene-4-phosphonic acid) synthesized by us show the best stability against radical degradation (determined ex situ by the Fenton Test8). The literature also contains blends of polybenzimidazole and dialkylated polybenzimidazole, which are used as stable anion exchange membranes18, 19, 20. A variety of different polymers are currently used as backbone polymers for the production of novel AEMs: among others, ethylene-tetrafluoroethylene, polyetherether ketones, polyethersulfone, poly (ether sulfone ketone), polyethylene, polyphenylene oxide, polystyrene, polyvinyl acetate, poly (vinylbenzyl chloride), polyvinylidene fluoride. Table 1 shows a comprehensive compilation of relevant non-commercial AEMs, which are also compared to the benchmark membrane Tokuyama A201. The 28 μm thick commercial Tokuyama membrane A201 (development cords A006) has a hydroxide conductivity of approx. 40 mS·cm−1 (23° C. and RH=90%) according to the manufacturer21. The corresponding IEC value is 1.7 meq·g−1. The benchmark membrane was characterized for the purposes of the present invention under the same measuring conditions.
In the framework of this invention, PBI blend membranes, which are covalently and/or ionically cross-linked, are described, which are produced with halomethylated and optionally sulfonated and/or phosphonated polymers and are tailor-made in terms of their properties. If desired, the blend membranes are additionally covalently crosslinked, for example by the addition of a low molecular weight and/or a macromolecular crosslinker. Depending on the chosen composition, the membranes can be used in electrochemical processes as low-temperature cation exchange membranes, low-temperature anion exchange membranes (temperature range unpressurized to 100° C. or under pressure up to 150° C.) or doped with protonic conductors such as phosphoric acid and/or phosphonic acids, they can be used in the medium temperature range up to 220° C. Examples of electrochemical processes in which these membranes are to be used are:
A) low-temperature hydrogen fuel cells or electrolysis (0-100° C. depressurized or 0-130° C. under pressure)
(B) low-temperature direct fuel cells with fuels from the chemical group of alcohols such as methanol, ethanol, ethanediol, glycerol or ether fuels such as dimethyl ether or diethyl ether or various glymes (glyme, diglyme, triglyme . . . )
C) Intermediate temperature fuel cells or electrolysis (0-220° C.)
D) Intermediate temperature depolarized electrolysis (eg SO2 electrolysis)
E) Redox-flow batteries (for example all-vanadium, iron-chromium, etc.)
In the following, exemplary membrane types which are suitable for the respective electrochemical applications are described.
The anion exchange membranes consist of the following components:
A) a polybenzimidazole (PBI) as a matrix polymer, the following polybenzimidazoles being exemplified as ABPBI, PBI Celazole, p-PBI, F6PBI, SO2PBI and PBIOO. The recurring occurrence of the benzimidazole moiety in the main chain or side chain of the polymer is characteristic of the polybenzimidazoles used.
B) a halomethylated polymer (main chain selected from the group of polystyrenes and polystyrene copolymers, aryl main chain polymers (for example, polyether sulfones, polyether ketones, polysulfones, polybenzimidazoles, polyimides, polyphenylene oxides, polyphenylenesulfides) and any combinations as random copolymers, block copolymers, alternating copolymers), which carry the functional group —CR2HaI with R=HaI, alkyl radical, aryl radical and HaI=Cl, Br, I.
C) an alkyl halide (monohaloalkane, dihaloalkane, oligohaloalkane, monobenzyl halide, dibenzyl halide, tribenzyl halide, etc.), diiodopropane, diiodobutane, diiodopentane, diiodohexane diiodheptane, diiodoctane, diiodononane, diiododecane, etc.
D) optionally a monoalkylated polybenzimidazole
E) any polymer having cation exchange groups, eg, SO3X, PO3X2, COOX, SO2X and X═H, alkali metal, alkaline earth metal, ammonium, imidazolium, pyridinium.
The anion exchange groups of the blend are in molar excess over the other functional groups such as, for example, cation exchange groups. The anion exchange polymer blend membranes can thereby obtain the anion exchange groups in the following ways:
a) The solution of the mixture of the above polymers in a dipolar aprotic solvent (NMP, DMAc, DMF, DMSO, NEP, sulfolane, etc.), a basic nitrogen compound, such as for example, tertiary amine NR3 (R=alkyl, aryl), Pyridine, (tetralkyl) guanidine, alkyl or aryl imidazole. The chemical compound containing tertiary nitrogen may contain one or more tertiary nitrogen atoms. The tertiary nitrogen compound may also be an oligomer (eg, a polyvinylpyridine). Thereafter, the polymer solution is doctored, sprayed or cast on a substrate, and the solvent is evaporated. Thereafter, the resulting membrane is aftertreated:
b) The mixture of the above polymers in a dipolar aprotic solvent is stirred or poured and the solvent removed. Thereafter, the nitrogen groups of the resulting membrane are quaternized by immersing them in a tertiary amine, an amine solution or a mixture of various tertiary amines. The aftertreatment of the membrane is then carried out in the following manner:
Surprisingly, it has been found that homogeneous, mechanically and chemically very stable anion exchange membranes can be produced by means of the described processes, which are substantially more stable than anion exchange membranes of the prior art.
Base Excess PBI Blend Membranes (Covalently or Covalent-Ionically Cross-Linked) for Doping with Phosphoric Acid or Phosphonic Acids for Application in Electrochemical Processes in the Temperature Range from 100 to 220° C.
These membranes consist of a molar excess of a polybenzimidazole wherein the polybenzimidazole may be differently cross-linked to limit its phosphoric acid or water uptake. The membranes may consist of the following components:
a) a polybenzimidazole (PBI) as a matrix polymer (as example ABPBI, PBI Celazole, p-PBI, F6PBI, SO2PBI, PBIOO and any other polybenzimidazoles)
b) a halomethylated polymer (main chain selected from the group of polystyrenes and polystyrene copolymers, aryl main chain polymers (for example, polyether sulfones, polyether ketones, polysulfones, polybenzimidazoles, polyimides, polyphenylene oxides, polyphenylenesulfides) and any combinations as random copolymers, block copolymers, alternating copolymers), which carries the functional group —CR2HaI with R=HaI, alkyl radical, aryl radical and HaI═Cl, Br, I.
c) an alkyl halide (monohaloalkane, dihaloalkane, oligohaloalkane, monobenzyl halide, dibenzyl halide, tribenzyl halide, etc.), diiodopropane, diiodobutane, diiodopentane, diiodohexane diiodheptane, diiodoctane, diiodononane, diiododecane, etc.
d) optionally a monoalkylated polybenzimidazole
e) any polymer having cation exchange groups, eg, SO3X, PO3X2, COOX, SO2X and X═H, alkali metal, alkaline earth metal, ammonium, imidazolium, pyridinium.
Covalently cross-linked PBI blend membranes can consist of components a), b), c), d) and optionally a polymeric sulfinate RSO2X, covalent-ionically cross-linked membranes additionally contain cation exchange polymers which are listed under e).
After membrane production, the membranes are doped with phosphoric acid or phosphonic acid. The phosphoric acid/phosphonic acid absorption can be controlled by the concentration of the acid, by the bath temperature and by the residence time of the membrane in the phosphoric acid/phosphonic acid bath.
A covalently cross-linked PBI is obtained, for example, by:
a) mixture of the PBI with a halomethylated polymer wherein the halomethylated polymer reacts with one or both N-atoms of the imidazole group of the PBI by alkylation (
b) mixing the PBI with a monoalkylated PBI, a tertiary diamine (eg DABCO), a diiodoalkane (eg diiodobutane) and a polymeric sulfinate. There are various possibilities for the formation of a polymeric network of these components, which are listed in
A covalent-ionically cross-linked membrane is obtained as follows below:
a) a phosphonated and/or sulfonated polymer is added to the polymer mixture before evaporation of the solvent.
b) the polymer components of the membrane are subsequently sulfonated by aftertreatment of the membrane in a sulfuric acid bath of varying concentrations (30-100% H2SO4, depending on the reactivity of the polymers in the blend). Protonation of the imidazole groups of the PBI by the sulfonic acid groups subsequently introduced leads to ionic crosslinking sites.
c) If the polymer mixture also contains highly fluorinated aromatic polymers whose F atoms can be replaced nucleophilically by phosphonic acid groups (for example by the phosphonation reaction from7), the membrane is introduced into a solution containing tris(trimethylsilyl) phosphite. A part of the aromatic F is replaced by phosphonic acid silyl ester groups, which can be readily hydrolyzed to free phosphonic acid groups by boiling with water. Nucleophile-replaceable aromatic F bonds can also be replaced by other functional groups, for example by thiol groups, which can be used in a further step for crosslinking.
Surprisingly, it has been found that homogeneous, mechanically and chemically very stable intermediate temperature cation exchange membranes can be produced by means of the described processes which are more stable than intermediate-temperature cation exchange membranes of the prior art (for example, doped pure polybenzimidazoles).
These membranes consist of the following blend components:
a) cation exchange membranes with the sulfonic acid group SO3X or the phosphonic acid group PO3X2 (X═H, alkali metal, alkaline earth metal, ammonium, imidazolium, pyridinium)
b) a polybenzimidazole (PBI) as a matrix polymer (as example ABPBI, PBI Celazole, p-PBI, F6PBI, SO2PBI, PBIOO and any other polybenzimidazoles)
c) A halomethylated polymer (any main chain selected from the group of polystyrenes and polystyrene copolymers, aryl main chain polymers (for example, polyether sulfones, polyether ketones, polysulfones, polybenzimidazoles, polyimides, polyphenylene oxides, polyphenylene sulfides) and any combinations as random copolymers, block copolymers, alternating copolymers), which carry the functional group —CR2HaI with R=HaI, alkyl radical, aryl radical and HaI═Cl, Br, I.
d) optionally an alkyl halide (monohaloalkane, dihaloalkane, oligohaloalkane, monobenzyl halide, dibenzyl halide, tribenzyl halide, etc.), diiodopropane, diiodobutane, diiodopentane, diiodohexane diiodheptane, diiodoctane, diiodononane, diiododecane, etc.
e) optionally a monoalkylated polybenzimidazole
In these membranes, the acidic groups are in molar excess so that these membranes are cation-conductive. The blend membranes are covalently crosslinked when they contain the components a), b), c) and optionally d) and e). By reacting the blend components b) and c) with one another (and optionally d) and e)), quaternary positively charged nitrogen groups are formed which form ionic crosslinking sites with the acid anions: [SO3]−+[NR4] (R=alkyl, aryl) which form stronger electrostatic interactions with one another than when only ionic crosslinking sites form between the acidic groups and protonated benzimidazolium groups, as would be the case in the mixture between the acidic polymer and the non-alkylated PBI. It is expected that the crosslinking sites [SO3]−+[NR4] (R=alkyl, aryl) together with the covalent crosslinking of the blend components b) and c) (and optionally still d) and e)) in redox-flow batteries (RFB) reduce the permeability of the membranes for metal cations, which minimizes the efficiency losses of the RFB application.
Surprisingly, it has been found that homogeneous, mechanically and chemically very stable low-temperature cation exchange membranes which are more stable than low-temperature cation exchange membranes of the prior art (for example acid-base blend membranes of cation exchange polymers with weak polymeric bases) can be produced by means of the described processes. In particular, it is surprising that the membranes of the invention are more stable than conventional aromatic acidic polymers, in particular also for use in redox-flow batteries in which the membranes are subjected to strongly oxidizing conditions.
Membranes are claimed which can be used in various electrochemical processes depending on the proportion of the respective main blend components. The main membrane types and their respective fields of application are listed in the tabular overview below (Table 2).
1cation conductor
2anion conductor
3proton conductor via (poly)phosphoric and/or phosphonic acid
Surprisingly, it was found that the membranes can be used either as cation exchange, anion exchange or intermediate temperature membranes, depending on the proportion of the various blend components listed in Table 2. In particular, it is surprising that multi-layered membranes (from alternating cation-exchange and anion-exchange layers) can also be produced, which have outstanding properties, particularly in the case of use in redox flow batteries, such as extremely high chemical stability and very low cation permeabilities.
0.75 g of the polybenzimidazole F6PBI is used as a 4% solution in N, N-dimethylacetamide (DMAc) as a 10 wt % solution in DMAc with 0.321 g of bromomethylated polyphenylene oxide (PPOBr, degree of bromination 1.7 CH2Br per PPO repeat unit) (the chemical structure of the blend components is depicted in
The membrane is then characterized as follows:
1.4 g of F6PBI are mixed as a 5% solution in DMAc with 0.3 g of PARBr1 as a 5% solution in DMAc and 0.3 g of the sulfonated polymer sPPSU as well as 0.488 g of 1-ethyl-2-methylimidazole (the polymer structures are shown in
After homogenization, a membrane is doctored on a glass plate from this solution, and the solvent is stripped off at 140° C. in a convection drying oven. The membrane is then peeled off under water and after-treated as follows: 48 hours of 10% HCl at 90° C., then 48 hours of deionized water at 60° C.
Doping with 85% H3PO4 (259% doping degree), the conductivity curve is presented in
0.5 g of F6PBI are mixed as a 5% solution in DMAc with 0.5 g of PPOBr as a 5% solution in DMAc and 0.107 g of the sulfonated polymer sPPSU and 1.08 ml of the tertiary amine N-methylmorpholine (the polymers of the blending componentsare depicted in
After homogenization, a membrane is doctored on a glass plate from this solution, and the solvent is stripped off at 140° C. in a convection drying oven. The membrane is then removed under water and after-treated as follows: 48 hours of 10% HCl at 90° C., then 48 hours of deionized water at 60° C. Reaction of a small part of the CH2Br groups with the imidazole-N—H under alkylation produces covalent crosslinking bridges.
The membrane is then characterized as follows:
Thickness 105 μm
0.12 g of F6PBI are mixed as a 5% solution in DMAc with 0.12 g of PARBr1 as a 5% solution in DMAc and 2 g of the sulfonated polymer sPPSU and 0.195 g of 1-ethyl-2-methylimidazole (the polymers of the blending components are shown in
After homogenization, a membrane is doctored on a glass plate from this solution, and the solvent is stripped off at 140° C. in a convection drying oven. The membrane is subsequently removed under water and treated as follows: 48 hours of 10% HCl at 90° C., then 48 hours of demineralized water at 60° C. Covalent cross-linking bridges are formed by reaction of a small part of the CH2Br groups with the imidazole N—H via alkylation.
The membrane is then characterized as follows:
0.8 g of F6PBI are mixed as a 5% solution in DMAc with 1.2 g of PARBr1 as a 5% solution in DMAc and 0.12 g of the sulfonated polymer sPPSU and 1.95 g of 1-ethyl-2-methylimidazole (the polymer blend components are depicted in
After homogenization, a membrane is doctored on a glass plate from this solution, and the solvent is stripped off at 140° C. in a forced-air drying cabinet. The membrane is then removed under water and after-treated as follows: 48 hours of 10% HCl at 90° C., then 48 hours of deionized water at 60° C. Reaction of a small part of the CH2Br groups with the imidazole-N—H under alkylation produces covalent crosslinking bridges.
The membrane is then characterized as follows:
0.162 g of F6PBI are mixed as a 5% solution in DMAc with 0.243 g of PAK 18r as a 5% solution in DMAc and 0.081 g of the sulfonated polymer sPPSU and 0.45 ml of the tertiary monoamine N-methylmorpholine (polymeric acid base blends).
After homogenization, a membrane is poured from this solution into a petri dish, and the solvent is stripped off at 80° C. in a forced-air drying cabinet. Subsequently, the membrane is removed under water and treated as follows: 48 hours in a mixture of 50/50 DABCO/EtOH at 80° C., then 48 hours in deionised water at 90° C. Reaction of a small part of the CH2Br groups with the imidazole-N—H under alkylation produces covalent crosslinking bridges. The membrane is further covalently cross-linked by the diamine.
0.15 g of F6PBI are mixed as a 5% solution in DMAc with 0.10 g of PPOBr as a 5% solution in DMAc and 0.26 ml of the imidazole compound 1-methylimidazole (polymer blends)
64-PPO-50-PBIOO-Melm:
0.125 g of F6PBI are mixed as a 5% solution in DMAc with 0.125 g of PPOBr as a 5% solution in DMAc and 0.33 ml of the imidazole compound 1-methylimidazole (polymer blends)
67-PPO-50-PBIOO-EtMelm:
0.125 g of F6PBI are mixed as a 5% solution in DMAc with 0.125 g of PPOBr as a 5% solution in DMAc and 0.47 ml of the imidazole compound 1-ethyl-2-methylimidazole (polymer blends)
After homogenization, a membrane is poured onto a petri dish from the polymer solution, and the solvent is stripped off at 80° C. in a circulating air drying cabinet. Subsequently, the membranes are removed under water and rinsed in demineralised water at 90° C. for 48 hours. Reaction of a small part of the CH2Br groups with the imidazole-N—H under alkylation produces covalent crosslinking bridges. The membranes are characterized as follows:
37-PPO-50-F6PBI-NMM-TMEDA:
0.2025 g of F6PBI are mixed as a 5% solution in DMAc with 0.2025 g of PPOBr as a 5% solution in DMAc and 0.44 ml of the tertiary monoamine N-methylmorpholine (covalently cross-linked polymer blends).
After homogenization, a membrane is poured from the solution onto a petri dish, and the solvent is stripped off at 80° C. in a re-circulated drying cabinet. Subsequently, the membrane is removed under water and after-treated as follows: 48 hours in TMEDA (1 d RT, 1 d 50° C.), then 48 hours in demineralized water at 90° C. Reaction of a small part of the CH2Br groups with the imidazole-N—H under alkylation produces covalent crosslinking bridges. The membrane is further covalently cross-linked by the diamine.
40-PPO-50-F6PBI-SAC-5-NMM-TMEDA:
0.2025 g of F6PBI is added as a 5% solution in DMAc with 0.2025 g of PPOBr as a 5% solution in DMAc and 0.02025 g of the sulfonated polymer as a 5% solution in DMAc and 0.59 ml of the tertiary monoamine N-methylmorpholine (covalently cross-linked polymer blends)
After homogenization, a membrane is poured from the solution onto a petri dish, and the solvent is stripped off at 80° C. in a re-circulated drying cabinet. Subsequently, the membrane is stripped under water and treated as follows: 48 hours in TMEDA (1 d RT, 1 d 50° C., then 48 hours in demineralised water at 60° C. By reaction of a small part of the CH2—Br groups with the imidazole —NH under alkylation, covalent crosslinking bridges are formed.
The TGA traces of the membranes in 65% O2 are presented in
0.2025 g of F6PBI are added as a 5% solution in DMAc with 0.2025 g of PPOBr as a 5% solution in DMAc and, depending on the membrane, with 0.02025 g of SAC (44-PPO-50-F6PBI-SAC-5-NMM DABCO), 0.0405 g SAC (45-PPO-50-F6PBI-SAC-10-NMM-DABCO) or 0.06075 g SAC (46-PPO-50-F6PBI-SAC-15-NMM-DABCO) 5% solution in DMAc and 0.59 ml of the tertiary monoamine N-methylmorpholine (ionic-covalently cross-linked acid-base blends).
The TGA traces of the membranes in 65% O2 are presented in
0.2025 g of F6PBI are added as a 5% solution in DMAc with 0.2025 g of PPOBr as a 5% solution in DMAc and, depending on the membrane, with 0.02025 g of SAC (71-PPO-50-F6PBI-SAC-5-NMM), 0.0805 g SAC (72-PPO-50-F6PBI-SAC-10-NMM), 0.0605 g SAC PPO-50-F6PBI-SAC-20-NMM), or 0.5 g of the tertiary monoamine N-methylmorpholine (ionical-covalently crosslinked acid base-blends) After homogenization, a membrane is poured from the solution onto a petri dish, and the solvent is stripped off at 80° C. in a re-circulated drying cabinet. Subsequently, the membrane is stripped under water and treated as follows: 48 hours in 15% NMM in EtOH (1 d RT, 1 d 50° C.), then 48 hours in demineralised water at 90° C. Reaction of a small part of the CH2Br groups with the imidazole-N—H under alkylation produces covalent crosslinking bridges. The oxygen atom belonging to the morpholine also contributes to further chain-crossing hydrogen bonds within the membrane.
The TGA traces of the membranes in 65% O2 are presented in
Table 8 shows the compositions of various AEM blends, and Table 9 shows some of their properties.
1Structural formula (repeat unit) of PPOBr and F6PBI is depicted in Figure 5
2Structural formula (repeat unit) of PARBr1 and sPPSU is depicted in Figure 8
3Structural formula (repeat unit) of PBIOO and PVBCl is depicted in Figure 21
1value after storage in 1 molar KOH at 90° C. for 10 days (240 hours)
2Start of decomposition of the polymer (determined by TGA-FTIR coupling)
It can be clearly seen from Table 9 that all the AEM blend membranes studied have better chemical stability both after the KOH immersion and in the TGA experiment than the commercial benchmark membrane Tokuyama A201.
Due to their excellent properties, conductivity and long-term stability in alkaline media, the membranes are particularly suitable for sensors, especially ion-selective sensors and ion-selective applications, and for alkaline fuel cells.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 009 170.8 | Jun 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2015/000294 | 6/12/2015 | WO | 00 |
