Composites and Composite Membranes

Description

SUMMARY

Claimed are the following types of composite membranes:

1. Composites or composite membranes by addition of a metal salt, e. g. ZrOCl₂, in a solvent, e.g. DMSO, to a solution of one or more polymers in an organic solvent or in aqueous systems as well as the subsequent precipitation in the matrix of the hence produced composite membrane by post-treatment in an acid or in a salt solution, e.g. phosphoric acid.

2. Composites or composite membranes by subsequent ion exchange of finished polymer membranes with a suitable salt cation, e.g. ZrO₂⁺, whereas the polymer membrane if necessary is swollen prior to ion exchange with an organic solvent or a mixture of organic solvent with water as well as the subsequent precipitation of a sparingly soluble salt, e.g. of Zr₃(PO₄)₄, in the membrane by post-treatment in an acid or in a salt solution, e.g. phosphoric acid.

3. Composites or composite membranes by addition of nano-size Zr₃(PO₄)₄-powder to a polymer solution.

4. Claimed are also composites or composite membranes, which are produced as in 1. and/or 2 and/or 3, whereas additionally hetero polyacids are incorporated into the polymermorphologie or the membrane morphologie.

Claimed are also processes to produce polymers and membranes according to the invention.

STATE-OF-THE-ART

Composite membranes from organic polymers and inorganic fillers have been described often, and in fact in journals as well as in patents. A patent example, which contains also many hints to other developments in composite membranes, is a US patent of Lynntech, Inc.¹. In this patent however no composite membranes are described, whose organic phase is ionically and/or covalently cross-linked, as is the case in the present invention. In²composite membranes from Nafion® and zirconiumphosphate are described, where the zirconiumphosphate has been incorporated subsequently into the membrane by 1) ion exchange H⁺ against ZrO²⁺ in the Nafion®-membrane, 2) Soaking of the ion-exchanged Nafion®-membrane in phosphoric acid and precipitation of ZrO²⁺-ions in the membrane matrix as Zr-phosphates. Disadvantage of the method is however that only as much Zr-phosphate can be precipitated in the membrane, as are SO₃H-groups in the Nafion®-matrix. Also own developments in this field have been filed as patent: first composite-membranes from organic polymers and organic polymer blends containing cation exchange groups and/or basic groups alternatively non-ionic precursors of cation exchange groups, whereas acid-base-blends are preferred, and inorganic compounds, whereas the inorganic compounds are incorporated in the membrane matrix as organometalic compounds (such as e.g. metal acetylacetonates, metal alkoxides) and are hydrolysed in the membrane matrix to the respective metaloxide or metalhydroxide^3,4. The materials according to the invention respectively processes to produce the polymers and membranes according to the invention as described in this invention have not been described in the above mentioned own patent applications. A further group of composite membranes are composites from sulfonated poly(etherketones) and the hetero polyacids phosphoric tungsten acid hydrate H₃PW₁₂O₄₀x29 H₂O (TPA) and molybdatophosphoric acid hydrate H₃PMo₁₂O₄₀x29 H₂O (MPA) as well as the disodium salt of TPA (Na-TPA)⁵. In this publication no ionically and/or covalently cross-linked ionomer membranes have been described as is the case in the present invention. ¹U.S. Pat. No. 6,059,943, O. J. Murphy, A. J. Cisar, Lynntech, Inc. (2000)²C. Yang, et al., Electrochem. Solid St. Lett. 4(4) A31-A34 (2001)³Jochen Kerres, German patent application 10021106 from Feb. 5, 2000⁴Jochen Kerres, Thomas Häring, German patent application 10021104 from Feb. 5, 2000⁵S. M. J. Zaidi, S. D. Mikhailenko, G. P. Robertson, M. D. Guiver, S. Kaliaguine, J. Memb. Sci. 173, 17-34 (2000)

DESCRIPTION

It has been found surprisingly, that composites oder composite membranes made from polymer metal salt or polymer metal oxide or polymer metal hydroxide can be produced with the following method method 1 in the most general embodiment:

- I.1. Making of a solution of one or more polymers of the type A (polymer with cation exchange groups or their non-ionic precursors) and if necessary one or more polymers of the type B (polymers with N-basic groups and/or anion exchange groups) and if necessary of type C (polymers with cross-linking groups such as sulfinate groups and/or unsaturated groups) and/or polymers of the type D (polymers with cation exchange groups or their non-ionic precursors and anion exchange groups and/or basic N-groups and/or cross-linking groups) in a solvent L1 and if necessary a if necessary nano-sized metal oxide powder, metal salt powder or metal hydroxide powder(8);
- I.2. Making of a solution of one or more metal salts Me⁺X⁻ (10) in a suitable solvent L2 (11), if necessary by addition of a (hetero)polyacid or their alkali metal salt (9);
- I.3. Mixing of solutions from 1. and 2.;
- I.4. Casting or spraying of a thin film of the mixture of 3. on a support (foil or textile or nonwoven or glass plate or metal plate);
- I.5. Evaporation of the solvents L1 and L2 at elevated temperature and if necessary reduced pressure;
- I.6. Separation of the composite film from the support;
- I.7. Soaking of the composite film in the following liquids:
  - I.7a aqueous solution of a basic metal hydroxide MOH or an amine or ammonia N(R₂)₃at temperatures from 0° C. to 100° C., at which precipitation of a sparingly soluble metal oxide Me_mO_nor metal hydroxide Me_m(OH)_nor mixed metal oxide-hydroxide Me_mO_n*xH₂O in the membrane matrix takes place;
  - I.7b aqueous solution of an inorganic acid HY at temperatures from 0° C. to 100° C., which precipitates a sparingly soluble metal salt Me_mY_nin the membrane matrix;
  - I.7c water at temperatures from 0° C. to 100° C.,
  - I.7d aqueous solution of a metal salt MY at temperatures from 0° C. to 100° C., which precipitates a sparingly soluble metal salt Me_mY_nby Ion exchange in the membrane matrix.

Furthermore it has been found surprisingly, that composites or composite membranes made from polymer metal salt or polymer metal oxide or polymer metal hydroxide can be produced with the following method method II in the most general embodiment:

- II.1. Making of a solution of one or more polymers of the type A (polymer with cation exchange groups or their non-ionic precursors) and if necessary one or more polymers of the type B (polymers with N-basic groups and/or anion exchange groups) and if necessary of type C (polymers with cross-linking groups such as sulfinate groups and/or unsaturated groups) and/or polymers of the type D (polymers with cation exchange groups or their non-ionic precursors and anion exchange groups and/or basic N-groups and/or cross-linking groups) and if necessary addition of a cross-linker (e.g. Alkylation cross-linker (e.g. α,ω-dihalogenalkane)) or radical starter in a solvent L1 and if necessary a if necessary nano-sized metal oxide powder, metal salt powder or metal hydroxide powder and/or a (hetero)polyacid;
- II.2. Casting or spraying of a thin film of the mixture of 1. on a support (foil or textile or nonwoven or glass plate or metal plate);
- II.3. Evaporation of the solvent L1 at elevated temperature and if necessary reduced pressure; during the solvent evaporation takes place if necessary the cross-linking of the cross-linker;
- II.4. Separation of the composite film from the support;
- II.5. Soaking of the composite film in the following liquids:
  - II.5a water or mixture of water with organic solvent L1 at temperatures from 0° C. to 100° C.;
  - II.5b aqueous solution or solution of one or more metal salts Me⁺X⁻ or solution of one or more metal salts Me⁺X⁻ in a mixture of water and organic solvent L2 at temperatures from 0° C. to 100° C.; in doing so ion exchange takes place: Polymer-R⁻C⁺+Me⁺X⁻→Polymer-R⁻Me⁺+C⁺X⁻
    - Me⁺ represents any 1- to 4-valent metal cation or metal oxycation, X⁻ represents any ^anion, R⁻ represents any Polymer-fixed-anion, C⁺ represents any counter ion (any cation)
  - II.5c water at temperatures from 0° C. to 100° C.;
  - II.5d aqueous solution of a basic metal hydroxide MOH at temperatures from 0° C. to 100° C., at which precipitation of a sparingly soluble metal oxide Me_mO_nor metal hydroxide Me_m(OH)_nin the membrane matrix takes place;
  - II.5e water at temperatures from 0° C. to 100° C.;
  - II.5f aqueous solution of an inorganic acid HY at temperatures from 0° C. to 100° C., which precipitates a sparingly soluble metal salt Me_mY_nin the membrane matrix;
  - II.5g aqueous solution of a metal salt MY at temperatures from 0° C. to 100° C., which precipitates a sparingly soluble metal salt Me_mY_nby ion exchange in the membrane matrix,
  - II.5h water at temperatures from 0° C. to 100° C.;
  - II.5i one-time or several times repetition of the procedure 5a to 5h.

Thereby it has been found surprisingly, that the production processes Method I and Method II can be combined as follows:

First the composite film is produced according to Method I. Then the process is carried out according to methode II starting from II.5. Thereby multinary composite films are formed, which due to the incorporation of inorganic components into the various areas of the polymermorphologie show very good mechanical and thermal stability as well as very good ion conductivity and in use in direct methanol fuel cells also very good methanol retention. The advantages of the composite membranes produced according to Method I or Method II or a combination of Method I with Method II are:

- the by ion exchange precipitation in the polymer matrix incorporated if necessary self-proton conducting inorganic substances according to Method II, II.5 are mainly incorporated in the ion conducting channels. There they increase the proton conductivity of the membrane also at temperatures >100° C., because the inorganic substances especially at temperatures >100° C. increase the water retention capacity of the composite membrane and show also in part a self proton conductivity (such as e.g. heteropolyacids, vanadineoxide, zirconiumphosphate);
- the composite membranes produced according to Method I or Method II or a combination of Method I with Method II show great mechanical stability, because the network of the inorganic component(s) reaches out over the entire morphology. Furthermore the inorganic components increase the thermal stability of the composite membranes substantially;
- the composite membranes exhibit due to the inorganic components in the membrane matrix a very low methanol cross-over, which increases the efficiency of the membranes if used in direct methanol fuel cells (DMFC) considerably, whereby the efficiency is increased especially at temperatures >100° C. by the inorganic component(s) due to their good water retention capacity. If a DMFC is run at temperatures >100° C., the efficiency is increased also by the faster electrode kinetic in this temperature range (middle temperature-DMFC). The MeOH-retention is especially pronounced for composite membranes according to the invention, where the inorganic compound is incorporated into the ion-conducting channels (such as e.g. for II.5). The MeOH-retention of composite membranes produced according to II.5 can be surprisingly further increased, if the ion exchange precipitation process is repeated several times.
- It has been found surprisingly, that soaking of a membrane in a mixture of water and organic solvent (II.5.a) before the ion exchange precipitation process leads to a proportional increase of the ion conductivity of the membrane compared to the proportion of the organic solvent in the solvent/water mixture.
- It has been found surprisingly, that heteropolyacids in the membrane matrix are better retained, if a sparingly soluble inorganic phase is present in the composite membrane. If no inorganic phase is present in the membrane, the hetero polyacids are rinsed out for the greater part during the post-treatment step in water, acids and/or aqueous base.
- It has been complementary detected, that especially oxide- or salt-polymer-composite(blend)membranes, which contain ionical cross-linking places in the organopolymercomponent, exhibit a very high MeOH-retention, as compared to the corresponding pure organopolymer(blend)membranes.
- It has been found surprisingly, that in the polymerphase covalently and/or ionically cross-linked oxide- or salt-polymer-composite(blend)membranes show a especially good swelling stability also at temperatures >70° C., as compared to the corresponding pure organopolymer(blend)membranes.
- If polymer mixtures according to the invention, e.g. a sulfonated polymer (e.g. sulfonated PEK in the imidazole ion salt form SO₃⁻ImH⁺) and a basic polymer (e.g. polybenzimidazole PBI Celazol®), are mixed in a dipolar-aprotic solvent, e.g. N-methylpyrrolidinone, in addition with heteropolyacids, surprisingly there is no significant precipitation of polyelectrolyte complexes of basic polymer and heteropolyacid, as it could be expected.

The components of the composite membranes according to the invention are defined as follows:

(1) Main Chains (Backbones) of Polymers According to the Invention:

As polymer main chains all polymers are possible. Preferred as main chains are however:

- polyolefines such as polyethylene, polypropylene, polyisobutylene, polynorbornene, polymethylpentene, poly(1,4-isoprene), poly(3,4-isoprene), poly(1,4-butathene), poly(1,2-butathene)
- styrol(co)polymers such as polystyrole, poly(methylstyrol), poly(α,β,β-trifluorstyrol), poly(pentafluorostyrol)
- perfluorinated ionomeres such as Nation® or the SO₂Hal-precursor of Nafion® (Hal represents F, Cl, Br, I), Dow®-Membrane, GoreSelect®-Membrane.
- N-basic polymers such as polyvinylcarbazole, polyethylenimine, poly(2-vinylpyridine), poly(3-vinylpyridine), poly(4-vinylpyridine)
- (Het)arylmain chain polymers containing the construction units from FIG. 1.

Especially preferred are (Het)arylmain chain polymers such as:

- polyetherketone such as polyetherketone PEK Victrex®, polyetheretherketone PEEK Victrex®, polyetheretherketoneketone PEEKK, polyetherketonetherketoneketone PEKEKK Ultrapek®
- polyethersulfones such as Polysulfon Udel®, Polyphenylsulfon Radel R®, polyetherethersulfones Radel A®, polyethersulfone PES Victrex®
- poly(benz)imidazole such as PBI Celazol® and other oligomers and polymers containing the (benz)imidazole-unit, in which the (benz)imidazole group can be present in the main chain or in the side chain
- polyphenylenether such as poly(2,6-dimethyloxyphenylen), poly(2,6-diphenyloxyphenylen)
- polyphenylensulfide and copolymers
- poly(1,4-phenylene) or poly(1,3-phenylene), which can be modified in the side chain with benzoyl-, naphtoyl- or o-phenyloxy-1,4-benzoylgroups, m-phenyloxy-,1,4-benzoylgroups or p-phenyloxy-1,4-benzoylgroups,
- poly(benzoxazole) and copolymers
- poly(benzthiazole) and copolymers
- poly(phtalazinone) and copolymers
- polyaniline and copolymers
- polythiazoles
- polypyrroles

(2) Polymers of Typ A (Polymers with Cation Exchange Groups or Their Non-Ionic Precursors):

Polymertyp A comprises all polymers, composed from the above mentioned Polymermain chains (1) and the following cation exchange groups or their non-ionic precursors:

SO₃H, SO₃Me; PO₃H₂, PO₃Me₂; COOH, COOMe

SO₂X, POX₂, COX with X represents Hal, OR₂, N(R₂)₂, anhydride radical, N-imidazolee radical

N-pyrazole radical

- 1. Preferred as functional groups are SO₃H, SO₃Me; PO₃H₂, PO₃Me₂respectively SO₂X, POX₂. Especially preferred as functional groups are the strong acidic sulfonic acid groups or their non-ionic precursors. As polymermain chains preferred are aryl main chain polymers. Especially preferred are poly(etherketones) and poly(ethersulfones).

(3) Polymers of Typ B (Polymere with N-Basic Groups and/or Anion Exchange Groups):

Polymertyp B comprises all polymers, composed from the above mentioned (1) and from the following anion exchange groups or their non-ionic precursor (with primary, secondary or tertiary basic N):

N(R₂)₃⁺Y⁻, P(R₂)₃⁺Y⁻, whereat R₂radicals can be the same or different from each other;

N(R₂)₂(primary, secondary or tertiary amines);

Polymere with N-basic (Het)aryl- and Heterocyclic groups as in FIG. 2.

As polymer main chains preferred are (Het)aryl main chain polymers such as poly(etherketones), poly(ethersulfones) and poly(benzimidazolee). As basic groups preferred are primary, secondary and tertiary amino groups, pyridylgroups and imidazolee groups.

(4) Polymers of Typs C (Polymers with Cross-Linking Groups such as Sulfinate Groups and/or Unsaturated Groups):

Polymertyp C comprises all polymers composed from the above mentioned polymer main chains (1) and cross-linking groups. Cross-linking groups are e.g.:

- 4a) alkene groups: polymer-C(R₁₃)═C(R₁₄R₁₅) with R₁₃, R₁₄, R₁₅═R₂or R₄
- 4b) polymer-Si(R₁₆R₁₇)—H with R₁₆, R₁₇═R₂or R₄
- 4c) polymer-COX, polymer-SO₂X, polymer-POX₂
- 4d) sulfmate groups polymer-SO₂Me
- 4e) polymer-N(R₂)₂with R₂≠H.

Thereby one or more of the mentioned cross-linking groups can be present on the polymer main chain. The cross-linking can be carried out according to the following reactions known from the literature:

- (I) group 4a) by addition of peroxides;
- (II) group 4a) with group 4b) by Pt-catalysis via hydrosilylation;
- (III) group 4d) with dihalogenalkane- or dihalogenaryl cross-linking agents (e.g. Hal-(CH₂)_x-Hal, x represents a number between 3 and 20) by S-alkylation of the sulfinate group;
- (IV) group 4e) with dihalogenalkane- or dihalogenaryl cross-linking agents (e.g. Hal-(CH₂)_x-Hal, x represents a number between 3 and 20) by alkylation of the tertiary basic N-group
- (V) group 4d) and group 4e) with dihalogenalkane- or dihalogenaryl cross-linking agents(e.g. Hal-(CH₂)_x-Hal, x represents a number between 3 and 20) by S-alkylation of the sulfinate group and alkylation of the tertiary basic N-group
- (VI) group 4c) by reaction with diamines.

Thereby the cross-linking reactions (III), (IV) and (V) are preferred, especially the cross-linking reaction (III).

(5) Polymers of Typ D (Polymers with Cation Exchange Groups and Anion Exchange Groups and/or Basic N-Groups and/or Cross-Linking Groups):

Polymertyp D comprises all polymers carrying the main chains from (1), which can carry different groups: cation exchange groups or their non-ionic precursors as in (2) and anion exchange groups or primary, secondary or tertiary N-basic groups as in (3) and/or the cross-linking groups as in (4).

The following combinations are possible:

- Polymer D1: polymer with cation exchange groups or their non-ionic precursors and with anion exchange groups or with N-basic groups
- Polymer D2: polymer with cation exchange groups or their non-ionic precursors and with cross-linking groups
- Polymer D3: polymer with anion exchange groups and with cross-linking groups
- Polymer D4: polymer with cation exchange groups or their non-ionic precursors and with anion exchange groups and with cross-linking groups

(6) Typs of Membranes:

(6.1) Covalently Cross-Linked (Blend)Membranes:

The covalently cross-linked (blend)membranes can consist of the following components:

(6.1.1) blend membranes from:

(6.1.1.1) polymer A: main chain (1) with cation exchange groups (2)

- +polymer C: main chain (1) with cross-linking groups (4)
- +cross-linking agent or cross-linking starter

(6.1.1.2) polymer D2: main chain (1) with cation exchange groups (2) and cross-linking groups (4)

- +Polymer C: main chain (1) with cross-linking groups (4)
- +cross-linking agent or cross-linking starter

(6.1.2) polymer D2: main chain (1) with cation exchange groups (2) and cross-linking groups (4)

- +cross-linking agent or cross-linking starter

As main chains (1) aryl main chain polymers are preferred aril especially poly(etherketones) or poly(ethersulfones), as cation exchange groups (2) SO₃H-groups or phosphonic acid groups or their non-ionic precursors, and as cross-linking groups (4) SO₂Me-groups. As cross-linking agents dihalogenalkane- or dihalogenaryl compounds are preferred. Especially preferred as cross-linking agents are Hal-(CH₂)_x-Hal, x represents a number between 3 and 20, with Hal=I, Br, Cl, F.

(6.2) Ionically Cross-Linked (Blend)Membranes:

The ionically cross-linked (blend)membranes can consist of the following components:

(6.2.1) blend membranes from:

(6.2.1.1) polymer A: main chain (1) with cation exchange groups (2)

- +polymer B: main chain (1) with anion exchange groups or with N-basic groups (3)

oder

(6.2.1.2) polymer D1: main chain (1) with cation exchange groups (2) and anion exchange groups or with N-basic groups (3)

- +polymer B: main chain (1) with anion exchange groups or with N-basic groups (3)

(6.1.2) polymer D1: main chain (1) with cation exchange groups (2) and anion exchange groups or with N-basic groups (3)

As main chain (1) aryl main chain polymers are preferred and especially poly(etherketones) or poly(ethersulfones), as cation exchange groups (2) SO₃H-groups or phosphonic acid groups or their non-ionic precursors.

(6.3) Covalent-Ionically Cross-Linked (Blend)Membranes:

The covalently-ionically cross-linked (blend) membranes can consist of the following components:

(6.3.1) blend membranes from:

(6.3.1.1) polymer A: main chains (1) with cation exchange groups (2)

- +polymer C: main chains (1) with cross-linking groups (4)
- +polymer B: main chains (1) with anion exchange groups or with N-basic groups (3)
- +cross-linking agent or cross-linking starter

(6.3.1.2) polymer D2: main chains (1) with cation exchange groups (2) and cross-linking groups (4)

- +polymer B: main chains (1) with anion exchange groups or with N-basic groups (3)
- +cross-linking agent or cross-linking starter

(6.3.1.3) polymer D1: main chains (1) with cation exchange groups (2) and anion exchange groups or with N-basic groups (3)

- +polymer C: main chains (1) with cross-linking groups (4)
- +cross-linking agent or cross-linking starter

(6.3.1.4) polymer A: main chains (1) with cation exchange groups (2)

- +polymer B: main chains (1) with anion exchange groups or with N-basic groups (3)
- +cross-linking agent or cross-linking starter

(6.3.2) polymer D4: membranes from main chains (1) with cation exchange groups (2) and anion exchange groups or with N-basic groups (3) and cross-linking groups (4)

- +cross-linking agent or cross-linking starter

As main chains (1) aryl main chain polymers are preferred and especially poly(etherketones) or poly(ethersulfones), as cation exchange groups (2) SO₃H-groups or phosphonic acid groups or their non-ionic precursors, and as cross-linking groups(4) SO₂Me-groups. As cross-linking agents dihalogenalkane- or dihalogenaryl compounds are preferred. Especially preferred as cross-linking agents are Hal-(CH₂)_x-Hal, x represents a number between 3 and 20, with Hal=I, Br, Cl, F.

(7) Solvent L1:

(7.1) Protic Solvents:

Water, alcoholes (e.g. methanol, ethanol, n-propanol, i-propanol, tert. butanol); aqueous and/or alcoholic metal salt solutions, aqueous and/or alcoholic low-molecular polymer solutions conataining cation exchange groups;

(7.2) Dipolar-Aprotic Solvents:

acetone, methylethylketone (MEK), acetonitrile (ACN), N-methylformamide, N,N-dimethylformamide (DMF), N-methylacetamide, N,N-dimethylacetamide (DMAc), N-methylpyrrolidinone (NMP), dimethylsulfoxide (DMSO), sulfolane;

(7.3) Ether Solvents:

tetrahydrofurane, oxane, dioxane, glyme, diglyme, triglyme, tetraglyme, diethylether, di-tert. Butylether.

(8) Metal Oxide Powder, Metal Salt Powder or Metal Hydroxide Powder, Especially Preferred are Nano-Sized Powder:

- Phyllosilicate based on montmorillonite, smectite, illite, sepiolite, palygorskite, muscovite, allevardite, amesite, hectorite, talc, fluorhectorite, saponite, beidelite, nontronite, stevensite, bentonite, mica, vermiculite, fluorvermiculite, halloysite, fluor containing synthetical talc types or blends of two or more of the above-mentioned phyllosilicates.
- Natural and synthetical, if necessary ion exchanged zeolithes, especially ZSM-5 zeolith and klinopthiolites
- Addionally the carbonates are suitable such as e.g. MgCO₃xH₂O and La(CO₃)₂xH₂O as well as oxycarbonates and the proton conducting perowskitic oxides such as e.g. strontium-barium-ceroxide, barium-calcium-niobate etc. as ceramic components.
- Water containing particles, carrying OH-groups on their surface, preferably based on Al₂O₃(bayerite, pseudoböhmite, gibbsite=hydrargillite, diaspor, böhmit), as well as vanadium- or tungsten-based oxides (V₂O₅, VO_x, WO_x) or alloys from these oxides:

Al₂O₃*xH₂O
x = 1-10

V₂O₅*xH₂O
x = 1-10

VO_x*yH₂O
y = 1-10
x = 1.5-3

WO_x*yH₂O
y = 1-10
x = 2-3

- ion exchanged, especially preferred are protonated alloys of oxides, which form in their original composition the β-aluminate structure. This class of compounds is formed from alloys of the below mentioned oxides. The formulae of composition describe the range, in which the starting compound, the β-aluminate, is formed.

As preferred component Me in Me₂O Na or K is used. The produced, alkali containing compounds have to be ion exchanged before they can be used for the membrane. In doing so the alkali ion is removed and the protonated form is generated.

- zMe₂o-xMgO-yAl₂O₃, _zMe₂O-xZnO-yAl₂O₃, zMe₂O-xCoO-yAl₂O₃,
- zMe₂O-xMnO-yAl₂O₃, zMe₂O-xNiO-yAl₂O₃, zMe₂O-xCrO-yAl₂O₃,
- zMe₂O-xEuO-yAl₂O₃, zMe₂O-xFeO-yAl₂O₃,
- zMe₂O-xSmO-yAl₂O₃
- with Me=Na, K, z=0.7-1.2.

(with x=0.1-10, y=0.1-10), stable until appr. 300° C.

- Other suitable ceramic powders contain the components MgO, ZnO, CoO, MnO, NiO, CrO, EuO, FeO, SmO. Further suitable oxides are based on the elements Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ce, Ta, W, Sm, Eu, Gd, Yb, La
- Other suitable, in part sparingly soluble metal salts are: phosphates and hydrogenphosphates as well as acidic and entirely neutralised diphosphates of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ce, Ta, W, Sm, Eu, Gd, Yb, La.
- Also siliciumdioxide in its different modifications is suitable as ceramic component. Especially preferred are highly dispersed siliciumdioxides, e.g. from the Aerosile® group.

Especially preferred are the oxides TiO₂, ZrO₂and Al₂O₃and the sparingly soluble metal phosphates Zr₃(PO₄)₄and ZrP₂O₇and zirconhydrogenphosphates.

(⁹) (Hetero)polyacids and Their Salts:

As (Hetero)polyacids can be used: polyphosphoric acid and heteropolyacids such as phosphor-tungsten-acid hydrate H₃PW₁₂O₄₀x29H₂O (TPA) and molybdatophosphoricacid hydrat H₃PMo₁₂O₄₀x29H₂O (MPA) as well as the alkalimetalsalts of heteropolyacids such as e.g. the disodiumsalt of TPA (Na-TPA).

(10) Metal Salts Me⁺X⁻ and Covalent Metal Compounds:

The metal salts are salts of transition metal cations (e.g. of metals Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Sn, Nb, Mo, Ce, Ta, W, Sm, Eu, Gd, Yb, La) or transition metal oxycations such as ZrO²⁺, TiO²⁺, and anions of mineral acids, such as e.g. Hal⁻ (Hal=F, Cl, Br, I) or SO₄²⁻, which are in solvents L2 (see below) soluble. As metal salts are especially preferred ZrOCl₂, ZrOSO₄, TiOCl₂, TiOSO₄, ZrCl₄or TiCl₄.

(11) Organic Solvent L2:

As organic solvent for the metal salts (10) mainly dipolar-aprotic solvents are suitable. As solvent L2 is DMSO especially preferred.

(13) Cation Exchange Counter Ions C⁺:

As C⁺ are in principal all dissociating cations suitable. Preferred are however alkalimetal cations or primary, secondary or tertiary ammoniumions or pyrazolium- or imidazoleiumions as well as pyridiniumions.

(14) Basic Metal Hydroxides MOH or Amines:

Suitable basic metal hydroxides are the alkali hydroxides or the alkaline-earth hydroxides, thereby NaOH and KOH are preferred. Suitable amines are ammonia or triethylamine.

(15) Sparingly Soluble Metal Oxides Me_mO_n:

All in (8) mentioned oxides are in principle suitable as sparingly soluble metal oxides. Preferred are however the in part water-containing oxides, which form by reaction of compounds (10) with the aqueous bases (14). Thereby are especially preferred TiO₂or ZrO₂.

Sparingly Soluble Metal Hydroxides Me_m(OH)_n:

All in (8) mentioned hydroxides are in principle suitable as sparingly soluble metal hydroxides.

Mineral Acid HY:

Mono-, di- or polyphosphoric acid or heteropolyacids or sulfuric acid are suitable as mineral acids. Preferred is however ortho-phosphoric acid.

Examples of Application

1. Acid-Base-Blend-Composite-Membranes by Addition of a Solution of ZrOCl₂*8H₂O in Dimethylsulfoxide to the Polymer Solution

Preparations:

In this work blend membranes from sulfonated poly(etherketon) PEK (S-PEK; IEC=1.8 meq SO₃H/g Polymer) and PBI (IEC=6.5 meq basic N/g Polymer) as acid respective base component are produced. Another base (imidazolee) is used to neutralise S-PEK. As inorganic material, which is incorporated into the membranes, ZrOCl₂*8H₂O has been chosen. S-PEK and Imidazole are used as 10% solutions in NMP. A 9.5% PBI solution in DMAc was made. Due to the solubility and mixability with polymer solutions ZrOCl₂*8H₂O was dissolved in DMSO (also 10%).

solution 1:
S-PEK
10% in NMP

solution 2:
PBI
9.5% in DMAc

solution 3:
imidazolee
10% in NMP

solution 4:
ZrOCl₂*8H₂O
10% in DMSO

To produce clear membranes, all solutions have been filtered to seperate floating particles.

Membrane Production:

S-PEK solution was neutralised with imidazolee (solution 3), then PBI (solution 2) added and stirred. Then ZrOCl₂*8H₂O was added and stirred. For comparaison a membrane was made(CPM2) from a solution without addition of ZrOCl₂*8H₂O. The polymer solution was cast on a glassplate and coated with a doctor knife (1.0 mm notch). The glass plate was immediately stored in a drying oven at 120° C. for 3 h and then over night a vacuum applied. The glass plate was cooled to room temperature and finally to remove the membrane placed for some minutes in water. The membrane was cut into 3 sections and marked as A, B or C. The sections have been post-treated as followed:

- A: in 10% NaOH at 70° C., 24 h; then in DI water at 70° C., 24 h
- B: in 10% NaOH at 70° C., 24 h; rinsed with water; in 10% H₃PO₄, 70° C., 24 h; then in DI water at 70° C., 24 h
- C: in 10% H₃PO₄, 70° C., 24 h; then in DI water at 70° C., 24 h

The reference membrane CPM2 was treated as C, because it does not contain inorganic material.

The following membranes according to Table 1 were made:

TABLE 1

Membrane composition

S-PEK
Imidaz-
PBI
ZrOCl₂*8H₂O
ZrOCl₂*8H₂O

[g]
ole# [g]
[g]
[g]
%

CPM1
2.0015
0.8025
0.1906
0.3038
12*

CPM4
2.0017
0.8011
0.1915
0.6030
21.6*

CPM2
2.0019
0.8004
0.1962
0
0

(Refer-

ence)

#To neutralise the poly(etherketonsulfonic acid) SPEK

*Based to S-PEK and PBI

Results:

Swelling:

FIG. 3 shows the temperature dependant swelling of CPM1 and the reference membrane in water. At 60° C. both membranes show almost no temperature dependence. Between 60° C. and 90° C. however the water up-take of CPM1 rises circa 10% and of the reference membrane circa 20%. The swelling behaviour of the membranes treated by different ways is similar. The membrane treated by method A shows the least swelling, that by method C takes up about 10% more water.

If the quantity of ZrOCl₂*8H₂O is doubled (CPM4), the membrane reacts as follows: between 25° C. and 90° C. almost no water is taken up.

FIG. 4 shows the swelling behaviour of CPM4. The swelling of the membrane is between 28% and 45%.

The presence of the inorganic components causes apparently and surprisingly a stabilisation of the swelling over a wide temperature range.

In both cases (CPM1 and CPM4) the membrane sections treated with NaOH show the least swelling followed by those treated in H₃PO₄. The biggest water up-take capacity show the membranes post-treated in NaOH and then in H₃PO₄.

Determination of residue with TGA:

With thermal gravimetric analysis (TGA) the residues of the mentioned membranes have been measured. First small membrane sections are dried at 100° C. for 3 days in a drying oven. Then they are cut for the thermo balance. They are heated with a heating rate of 20K/min. under oxygen.

Table 2 shows the calculated and experimentally found residues of the membranes.

TABLE 2

Residues of membranes

Residue

Theo. ZrO(PO₃)₂or

(TGA) %
Theo. ZrO₂%
ZrP₂O₇%

CPM1
A
5.4
5.0
11.1

B
7.9

C
14.8

CPM4
A
8.1
9.4
16.1

B
24.2

C
15.9

CPM2 Reference
0
0
0

*A: treated NaOH,

*B: treated NaOH/H₃PO₄,

C: treated H₃PO₄

Membranes of the row A, post-treated in NaOH and according to equation 1 contain ZrO₂as residue, show a good match of the calculated value with the experimental result. (CPM1-A: 5.0%/5.4%; CPM4-A: 9.4%/8.1%).

When the zirkonoxidaquat, which is formed according to eq (1) during post-treatment, is treated with phosphoric acid (membrane section B), first an adsorption takes place⁶, which is slowly superposed by the formation of zirconphosphate (eq.2). The adsorption compound contains (formally) ZrO₂and P₂O₅, which releases on rinsing (formally) P₂O₅. ⁶E. Wedekind, H. Wilke, Koll.-Z. 34 [1924] 283/9, 284

During the annealing of the zirconphosphate as residue according to⁷remains zirkonylmetaphosphate ZrO(PO₃)₂. J. H. De Boer⁸however understands the residue as diphosphate (ZrP₂O₇). Independently from the different views both formulae are identical for the explanation of the analytical results. As a result the residue of the B row is ZrO(PO₃)₂or ZrP₂O₇. ⁷G. v. Hevesy, K. Kimura, Z.anorg.Ch. 38 [1925] 774/6; J. Am. Soc. 47 [1925] 2540/4⁸J. H. De Boer, Z. Anorg. Ch. 144 [1925] 190/6

Based on the assumption that (formally) P₂O₅is rinsed out partly during post-treatment, the experimentally found residue for CPM1-B of 7.9% corresponds to a value between pure ZrO₂and ZrO(PO₃)₂. However the high residue for CPM4B can not be explained in this way. The zirconphosphate (membrane section C) directly obtained with H₃PO₄from the solutions of Zr salts behaves differently. Due to the great stability of the ZrO²⁺ ion and the practical non-existence of Zr⁴⁺ ions in aqueous solutions G. v. Hevesy and K. Kimura⁷consider the formula ZrO(H₂PO₄)₂as propable. In this case P₂O₅(formally) can not be rinsed out⁶. The zirkonyldihydrogenphosphate transforms on annealing to metaphosphate ZrO(PO₃)₂. The observed residues for CPM1C and CPM4C compare well with the theoretical value for ZrO(PO₃)₂(CPM1-C: 14.8%/11.1%, CPM4-C: 15.9%/16.1%). ⁷G. v. Hevesy, K. Kimura, Z.anorg.Ch. 38 [1925] 774/6; J. Am. Soc. 47 [1925] 2540/4⁶E. Wedekind, H. Wilke, Koll.-Z. 34 [1924] 283/9, 284

The reference membrane CPM2 does not show a residue due to no inorganic components.

Ionic Capacity and Specific Resistance

The ionic capacity of a membrane is determined by soaking a membrane piece in an aqueous saturated sodium chloride solution. An ion exchange takes place Na⁺ ion diffusing into the membrane, and displacing H⁺ ions. The protons present in solution are titrated with NaOH to the equivalence point. From the consumed quantity of NaOH the direct ion capacity can be (IEC_direct) calculated. It corresponds to the number of free protons in the membrane. If overtitrated with NaOH, the ionic interaction of the membrane is broken. The overtitrated NaOH determined by backtitration corresponds to the quantity of ionic interaction and contributes to the total ion capacity (IEC_overall).

Table 3 shows the experimental and theoretical ion capacity of the membranes CPM1, CPM2 and CPM4.

TABLE 3

Ion capacity and specific resistance

IEC theo.
IEC exp.

meq SO₃H/g
meq SO₃H/g
Spec. resistance

direct
overall
direct
overall
Ω * cm

CPM1
A*
0.99

1.55

0.84

2.05

28.25

B

1.05
2.21
26.42

C
0.95
2.22
0.96
2.59
34.82

CPM4
A

0.94

1.48

0.58

1.96

10.5

B

0.63
2.62
19.4

C
0.85
2.67
0.8
2.53
29.3

CPM2 Reference.
1.06
1.64
0.96
1.52
39.6

*A: treated NaOH,

*B: treated NaOH/H₃PO₄,

C: treated H₃PO₄

For the calculation of the theoretical ion capacity of the row A (NaOH post-treatment) zircondioxide according to eq. (2) is taken into account among S-PEK and PBI in the matter balance, and for the row C (H₃PO₄post-treatment) ZrO(H₂PO₄)₂according to eq (3). Moreover the protons of dihydrogenphosphate are taken into account for the total ion capacity. There is no calculation for membranes of the row B (NaOH—H₃PO₄post-treatment) because from eq. (2) is not known how much (formally) P₂O₅is rinsed out. The IEC of this row of membranes must be intermediate compared to the IEC of the row A and C.

Good agreement between the theoretical and experimental IEC show membranes with inorganic component (CPM1 and CPM4) as well as the reference membrane without zircon compound (CPM2). Solely for the membranes post-treated with NaOH (row A) greater differences (marked in bold) are found.

Striking is the big difference between the IEC_directand IEC_overall, of CPM1-C and CPM4-C (circa 1.5 meq SO₃H/g/g) as compared to the reference membrane (circa 0.6 meq SO₃H). It is ascribed to the zircondihydrogenphosphate contained in these membranes, which releases both protons only in neutral to strongly basic medium⁹, and are therfore only taken into account during the determination of the total ion capacity. ⁹Holleman, Wiberg, Lehrbuch der Anorganischen Chemie, 91.-100. [1985] 653

These additional protons provided by the dihydrogenphosphate should decrease strongly the ionic resistance of the membrane. The resistance of membranes of row C should therefore be smaller than those of row A and B. The experimental fact however show a reversed picture. The reason of this discrepancy lies in the routine sample preparation for the determination of the membrane impedancy. For this purpose the membranes are cut into small pieces (ca. 1.5cm×1.5cm) and conditioned in 1N H₂SO₄. In this acidic medium the specific resistance is determined.

According to¹⁰zirconium sulphate Zr(SO₄)₂*4H₂O is formed from a solution containing ZrO₂and excess H₂SO₄. This exists in aqueous solution as a complex zirconium oxide sulphuric acid having the formula H₂[ZrO(SO₄)₂] and dissociates under liberation of protons according to equation 4. ¹⁰Gmelin, Handbuch Syst. Nr. 42 [1958] 337

Presumably the same reaction occurs in the membranes of the series A and partially also in in the series B. In both cases the sulphuric acid is bound in the membrane matrix and leads to a strong decrease of resistance. Due to the fact that sulphuric acid is a strong acid the effect is the more marked.

The experimentally determined membrane impedance reflects therefore not the actual ionic resistance, because it is falsified by the presence of sulphuric acid.

It is unclear whether the ions formed by the dissociation remain in the membrane and perpetuate the state of high protone conductivity, or are washed out with time.

The sparingly soluble zirconium dihydrogen phosphate in CPM1-C and CPM4-C is not influenced by this reaction¹⁰[5]. In the dihydrogen phosphate protons are present, they are however tightly bound and have less influence onto the proton conductivity than zirconium oxide sulfuric acid. ¹⁰Gmelin, Handbuch Syst. Nr. 42 [1958] 337

It is certain that composite membranes of this type have a smaller ionic resistance than a entirely organic membrane.

Summary:

- 1) The composite membranes have a lower ionic resistance than the membranes without inorganic components
- 2) the specific resistance of the A- and B-series is lower than the C-series because of the included zirconium phosphate. It is unclear whether the ions which are formed by dissociation are washed out of the membrane
- 3) The membranes of the C-series contain zirconium dihydrogen phosphate which strongly increases the overall ion-capacity. It is assumed that the protons of the dihydrogen phosphate partially contribute to proton conductivity. This effect is indicated by a lower specific resistance compared to the membrane without inorganic components (CPM1C, CPM4C compared to CPM2.
- 4) The high inorganic share in CPM4 leads to a constant swelling over a large temperature range.

Remarks:

- 1) Optical appearance of the membranes:

a)
S-PEK/Imidazolee/PBI/ZrOCl₂*8H₂O:
clear, transparent

b)
S-PEEK/Imidazole/PBI/ZrOCl₂*8H₂O:
clear, transparent

c)
S-PSU/ZrOCl₂*8H₂O
cloudy

d)
PSU/ZrOCl₂*8H₂O
cloudy

- 2) ZrOCl₂*8H₂O-DMSO-solution crystallizes with time. Repeating experiments of membrane preparation where the solution over the deposit is occupied, show that the membranes contain no zirconium and phosphorus (according to WDX method), and form no thermogravimetric residue.
  - For this reason the solution should always be prepared freshly.
- 3) Mechanical stability:
  - As could be ascertained via sensoric test, composite membranes, particularly in the system polyetherketone, are very stable. Over a broad mixing range no significant disadvantages, compared to entirely organic membranes, are recognizable. Only CPM4, containing an increased portion in zirconium compound, shows higher brittleness than CPM1.

2. Composite Membranes via Subsequent Ion-Exchange/Precipitation in Preformed Arylene Main Chain Blend Membranes

Investigated Membranes:

Membrane

composition
R_sp^H+(0.5N HCl)

[Nr.]
Type
[g]
[Ω * cm]^b

1025H
Covalently
4,066 PEK(SO₃H)_0.4^e
53.7

cross-linked^c
1.8 PSU(SO₂Li)^f

1025I
Covalently
4,066 PEK(SO₃H)_0.4^e
27

cross-linked
1.8 PSU(SO₂Li)^f

1030C
Covalently
2 PEEK(SO₃H)₁^g
35.9

cross-linked
2.3 PSU(SO₂Li)^f

810H
Ionically
4.5 PEK(SO₃H)_0.4
27.2

cross-linked^d
0.3 PBI^h

0.3 PSU-[C(OH)(4-

diethylaminophenyl)₂]ⁱ

a Impedance, measured between 2 Nafion ® 117 membranes in water

^bImpedance, measured between 2 Nafion ® 117 membranes in 0.5N HCl

^cCross-linking via alkylation of sulfinate groups with 1,4-diiodbutane¹¹

^dIonical cross-linking via proton transfer of SO₃H-group onto basic imidazole-N

^esulfonated poly(etherketon)e Victrex ®

^fsulfinated PSU, prepared via reaction of lithiated PSU with SO₂¹²

^gsulfonated poly(etherethe rketon)e Victrex ®

^hPolybenzimidazole Celazol ®

ⁱprepared via reaction of lithiated PSU with bis(diethylamino)benzophenone¹³

¹¹Jochen Kerres, Wei Cui, Martin Junginger, J. Memb. Sci. 139, 227-241 (1998)

¹²J. Kerres, W. Cui, S. Reichle, J. Polym. Sci.: Part A: Polym. Chem. 34, 2421-2438 (1996)

¹³J. Kerres, A. Ullrich, M. Hein, J. Polym. Sci.: Part A: Polym. Chem. 39, 2874-2888 (2001)

Preparation of Post-Treatment-Solution:

- 1. ZrOCl₂is dissolved in the following mixtures to a 1 molar solution:
  - Mixture 1: Water/NMP 70/30
  - Mixture 2: Water/NMP 50/50
  - Mixture 3: Water/NMP 30/70
- 2. 10% ige phosphoric acid is prepared via mixing of 85% phosphoric acid with water

Membrane-Posttreatment:

- 1. The membranes are immersed at room temperature for 24 h in the referring 1M ZrOCl₂-solution to exchange the H⁺-ions of the sulfonic acid group with ZrO²⁺-ions.
- 2. The membranes are immersed at room temperature for 24 h in deionized water to remove all residual ZrOCl₂from the membrane matrix.
- 3. The membranes are immersed at room temperature for 24 h in 10% phosphoric acid to precipitate Zr₃(PO₄)₄in the membrane matrix.
- 4. The membranes are immersed for 24 h in deionized water, to remove excess phosphoric acid out of the membrane matrix.

Results of Resistance Measurements of the Membranes with the Respective Posttreatment:

R_sp^H+(0.5N HCl)
R_sp^H+(0.5N HCl)
R_sp^H+(0.5N HCl)
R_sp^H+(0.5N HCl)

Reference
Mixture 1
Mixture 2
Mixture 3

membrane
[Ω * cm]
[Ω * cm]
[Ω * cm]
[Ω * cm]

810 H
53.7
24.4
15.35
8.07

1025 I
27
49.5
6.62
8.48

1025 H
27.2
51.3
27.3
5

1030 C
35.9
33.03
48.12
10.2

From the table can be seen (apart from run-offs) that the resistance of the membranes is decreasing with an increasing portion of NMP in the lmolar ZrOCl₂-solution The run-offs can result from the fact that the membrane-posttreatment was performed at room temperature, leading to limited accessibility of the membrane for the ion-exchange and precipitation reaction.

2. Composite Membranes via Subsequent Ion-Exchange/Precipitation in Preformed Binary Arylene Main-Chain Polymer Blend Membranes, into which Nano-Scaled Zirconium Phosphate “ZrP” was Mixed Prior to Membrane Preparation

a Preparation of Composite Membranes via Mixture of ZrP-Powder in Polymer Solutions, which Contain an Acidic (sPEK) and a Basic Polymer (PBI)

The polymer solutions are prepared in mass relation as indicated in the table. Subsequently the anorganic “ZrP” powder is added to the polymer solution.

PBI

SPEKH* (IEC =

sPEKH
soln.

Anorganic

Name
1.8)/g
PBI** g
Soln. (15%)
(12.1%)
Propylamine
component/g
wt %

ZrP 1a
2.25
0.15
15
1.25
1.5
ZrP*** 0.12
5

ZrP 1b
2.25
0.15
15
1.25
1.5
ZrP 0.24
10

ZrP 1c
2.25
0.15
15
1.25
1.5
ZrP 0.48
20

ZrP 1d
2.25
0.15
15
1.25
1.5
ZrP 0.72
30

*sulfonated polyetherketone (Producer: Victrex), IEC = 1.8 meq SO₃H/g

**Polybenzimidazole Celazol (Producer: Celanese)

***ZrP: finely dispersed layered zirconium phosphate, prepared via precipitation from

ZrOCl₂, from the group of Prof. Linkov, University of the Western Cape, South Africa

(30 g soln. for 2 membranes) onto one plate

4.5 g sPEKH (IEC = 1.8)
30 g soln. (15%)

3 ml propylamine

0.3 g PBI (10%)
3 g soln. (10%)

All solutions are warmed onto the magnetic stirrer prior to casting and are processed when warm.

800 μm-doctor knife, 2 membranes per glass plate, 2 h at 130° C./800 mbar, then vacuum 2 h/130° C., remove in H₂O, 2 d posttreatment with 10% HCl at 90° C., neutral-washing and post-treatment at 60° C. in H₂O.

The sensoric check of the membranes yields:

Name
Appearance
Homogeneous eity
Stability

ZrP 1a
brown, slightly turbid
slightly inhomogeneous eous
good

ZrP 1b
brown, slightly turbid
slightly inhomogeneous eous
good

ZrP 1c
brown, slightly turbid
slightly inhomogeneous eous
medium

ZrP 1d
brown, slightly turbid
slightly inhomogeneous eous
medium

b Change of the Membrane-Conductivity via Subsequent Introduction of Zirconium Compounds

Pieces of the membranes are swollen for 24 h at 60° C. in a solution of 30% NMP/70% H₂O The so-treated membranes are immersed in a 1 M ZrOCl₂solution and again treated for 24 h at 60° C. to exchange the H⁺-ions of the sulfonic acid groups with Zr⁴⁺. The membranes are washed with H₂O and are subsequently cut into 2 similarly big pieces (A+B). The Membranes A are treated in a 10% H₃PO₄-soln for 24 h at 60° C. (column “H” in table), the Membranes B referring in 10% NaOH (column “N” in table). The pieces are again washed with H₂O and heated for 24 h at 60° C. with 10% HCl to, transform them into the SO₃H-form. After the washing with H₂O small pieces are cut off to measure with them the swelling (25-, 40-, 60- and 90° C.), conductivity (only in HCl) and IEC. The further membrane pieces are again immersed in ZrOCl₂at 60° C. for 24 h, then treatment analogous to the first sequence.

- “0” means: respective property of the membrane before ZrOCl₂—H₃PO₄— or ZrOCl₂—NaOH-posttreatment
- “1” means: respective property of the membrane after the 1. ZrOCl₂—H₃PO₄— or ZrOCl₂-NaOH-posttreatment
- “2” means: respective property of the membrane after the 2. ZrOCl₂—H₃PO₄— or ZrOCl₂-NaOH-posttreatment

Zr₃(PO₄)₄
ZrP 1 a
ZrP 1 b
ZrP 1 c
ZrP 1 d

Swelling 0 25° C.
39.36 [%]
35.14
35.48
31.03

Swelling 0 40° C.
43.62
40.54
35.48
34.48

Swelling 0 60° C.
47.87
44.16
43.01
35.63

Swelling 0 90° C.
104.26
98.20
92.47
81.61

Spec. resistance 0
7.79 [Ohm · cm]
9.35
6.86
9.11

[HCl]
(78)
(67)
(70)
(73)

IEC directly
1.25
1.28
1.29
1.27

IEC overall
1.80
2.02
2.17
2.37

Swelling 1 25° C.
44.66
54.24
44.93
54.0
43.10
46.0
41.44
44.0

Swelling 1 40° C.
48.54
59.32
45.65
56.0
44.83
56.0
44.14
56.0

Swelling 1 60° C.
48.54
66.10
45.65
62.0
45.69
58.0
44.14
62.0

Swelling 1 90° C.
48.54
98.31
47.10
98.0
45.69
88.0
44.14
90.0

Spec. resistance 1
16.99
7.32
15.27
9.75
15.06
6.69
10.69
7.68

IEC directly
0.40
/
0.38
1.30
0.35
1.18
0.38
1.30

IEC overall
3.87
/
2.75
2.28
2.62
1.97
2.95
2.04

Swelling 2 25° C.
42.03
43.88
41.94
44.32
38.33
45.0
/
47.27

Swelling 2 40° C.
42.03
48.98
41.94
48.86
43.33
51.0
/
50.91

Swelling 2 60° C.
43.48
50.0
41.94
48.86
45.0
51.0
/
56.36

Zr₃(PO₄)₄
ZrP 1 a
ZrP 1 b
ZrP 1 c
ZrP 1 d
Zr₃(PO₄)₄
ZrP 1 a
ZrP 1 b
ZrP 1 c

Swelling 2 90° C.
43.48
54.08
43.55
61.36
45.0
61.0
/
69.09

Spec. resistance 2
14.47
10.39
14.82
6.48
11.27
23.21
14.32
7.01

IEC directly
1.71
0.08
1.97
0.07
1.82
0.09
1.76
0.08

IRC overall
5.13
0.25
5.83
0.21
5.20
0.17
5.88
0.17

H
N
H
N
H
N
H
N

4. Composite Membranes via Subsequent Ion-Exchange/Precipitation in Preformed Ternary Arylene Main-Chain Polymer Blend Membranes, into which was Mixed a Zirconium Phosphate “ZrP” as Nano-Scaled Powder Prior to Membrane Preparation

a Preparation of Composite Membranes via Mixture of ZrP-Powder in Polymer Solutions, Containing an Acidic Polymer (sPEK) and Two Basic Polymers (PBI and PSU-Ortho-Sulfone-(C(OH)(4-diethylaminophenyl)₂)

The polymer solutions are prepared in the mass relations which are indicated in the table. Subsequently the inorganic “ZrP” powder is added to the polymer solution.

Propyl-

sPEKH
PBI soln.
Amin/
inorg.
wt % in
A 1105

Name
sPEKH*/g
PBI/g
Soln.(15%)/g
(11.47%)/g
ml
component/g
Membrane
(15%)****

ZrP
2.25
0.15
15
1.31
1.5
ZrP*** 0.12
5
1

2a

ZrP
2.25
0.15
15
1.31
1.5
ZrP 0.24
10
1

2b

ZrP
2.25
0.15
15
1.31
1.5
ZrP 0.48
20
1

2c

ZrP
2.25
0.15
15
1.31
1.5
ZrP 0.72
30
1

2d

*sulfonated Polyetherketone (Producer: Victrex), IEC = 1.8 meq SO₃H/g

**Polybenzimidazole Celazol (Producer: Celanese)

***ZrP: finely dispersed layered zirconium phosphate, prepared via precipitation from

****ZrOCl₂, from the group of Prof. Linkov, University of the Western Cape, South Africa structure-formula:

Composition of the Standard Membrane 504 without ZrP)

sPEKH(IEC =

sPEKH
PBI soln.

Name
1.8)/g
PBI g
Soln.(15%)
(11.47%)
Propylamine
A 1105 (15%)

St 1a
2.25
0.15
15
1.31
1.5
1

St 1b
2.25
0.15
15
1.31
1.5
1

(30 g soln. for 2 membranes) onto one plate

4.5 g sPEKH (IEC = 1.8)
30 g soln. (15%)

3 ml propylamine

0.3 g PBI (11.47%)
2.61 g soln. (10%)

All solutions are warmed onto the magnetic stirrer prior to casting and are processed when warm.

60-doctor knife, 2 membranes per glass plate, 2 h at 130° C./800 mbar, then vacuum 2 h/130° C., remove in H₂O, 2 d posttreatment with 10% HCl at 90° C., neutral-washing and 1 post-treatment at 60° C. in H₂O

The sensoric check of the membranes yields:

Name
Appearance
Homogene eity
Stability

ZrP 2a
light-brown, slightly
homogeneous
good

turbid

ZrP 2b
light-brown, slightly
homogeneous
medium

turbid

ZrP 2c
light-brown, slightly
homogeneous
bad

turbid

ZrP 2d
light-brown, slightly
homogeneous
bad

turbid

St 1a
green, transparent
homogeneous
very good

St 1b
green, transparent
homogeneous
very good

b Change of the Membrane-Conductivity via Subsequent Introduction of Zirconium Compounds

- “0” means: respective property of the membrane before ZrOCl₂—H₃PO₄-posttreatment
- “1” means: respective property of the membrane after the 1. ZrOCl₂—H₃PO₄-posttreatment

A 504 Stand. 1
St 1a
A 504 Stand. 2
St 1b

Swelling 0 25° C.
25.40 [%]
Swelling 0 25° C.
22.55 [%]

Swelling 0 40° C.
26.98
Swelling 0 40° C.
23.53

Swelling 0 60° C.
30.16
Swelling 0 60° C.
24.51

Swelling 0 90° C.
45.24
Swelling 0 90° C.
38.24

Spec. resistance 0
41.42 [Ohm · cm]
Spec.
43.88

[HCl]
(53)
resistance 0
[Ohm · cm]

[HCl]
(40)

IEC directly
1.17
IEC directly
1.14

IEC overall
1.59
IEC overall
1.74

Zr₃(PO₄)₄
ZrP 2a
ZrP 2b
ZrP 2c
ZrP 2d

Swelling 0 25° C.
26.94 [%]
23.21
26.14
22.45

Swelling 0 40° C.
30.05
26.79
29.55
26.53

Swelling 0 60° C.
30.57
28.57
32.95
34.69

Swelling 0 90° C.
47.15
39.29
45.45
38.78

Spec. resistance 0
52.50
40.87
48.16
45.23

[HCl]
[Ohm · cm]
(63)
(56)
(66)

(50)

IEC directly
1.14
1.13
1.18
1.06

IEC overall
1.88
2.15
2.42
1.59

Swelling 1 25° C.
/
/
61.34
/
45.83
/
/
/

Swelling 1 40° C.
/
/
89.08
/
45.83
/
/
/

Swelling 1 60° C.
/
/
89.08
/
45.83
/
/
/

Swelling 1 90° C.
/
/
89.08
/
45.83
/
/
/

Spec. resistance 1
/
/
87.61
/
151.29
/
/
/

IEC directly
/
/
1.32
/
1.40
/
/
/

IEC overall
/
/
3.50
/
4.03
/
/
/

H
N
H
N
H
N
H
N

5. Composite Membranes via Subsequent Ion-Exchange/Precipitation in Preformed Ionically and/or Covalently Cross-Linked Arylene Main-Chain Polymer Blend Membranes 5.1 Membrane Preparation 5.1.1 Membrane 1202

The following polymers are mixed as 15 wt % solutions in N-methylpyrrolidinore (NMP):

- 4.222 g sulfochlorinated PEKEKK Ultrapek (IEC=3 meq SO₃H/g polymer (hydrolysed))
- 5.52 g PSU-SO₂Li (1 group per repeating unit)

After the homogenisation 0.7 ml diiodbutane are syringed into the polymer solution. After that a thin film of the polymer solution is cast onto a glass plate with a doctor knife to a thin film. The solvent is evaporated in a vacuum drying oven following the following method:

- 1) 2 hours at 90° C. and 800 mbar
- 2) 3 hours at 130° C. and 150-50 mbar

Subsequently the glass plate with the membrane is removed from the drying oven, and after cooling down it is immersed in a water bath. There the membrane comes off the glass plate. The membrane is posttreated in the following manner:

- 1) 48 h at 25° C. in 10% NaOH
- 2) 48 h at 90° C. in 7% HCl
- 3) 48 h at 60° C. in H₂O