Membrane from polyarylene polymer

Abstract

A dispersion comprising a polyarylene polymer comprising sulfonic acid ester functional groups and its use in the preparation of polymer electrolyte membranes.

Description

SSPU 2024 / 031MEMBRANE FROM POLYARYLENE POLYMERCross reference to related patent applications

[0001] The present application claims priorities filed on 9 September 2024 in the U.S.A, with No. 63 / 692604, and on 23 October 2024 in Europe with No. 24208272.5, the whole content of each of these applications being incorporated herein for all purposes.Technical Field

[0002] The invention relates to a liquid composition comprising polyarylene polymer having sulfonic acid functional groups and to its use in the preparation of polymer electrolyte membranes.Background Art

[0003] The use of polymer electrolyte materials as ion conducting materials in electrochemical devices is known. Polymers having proton conductivity, namely polymer electrolytes, are used as the separating membrane of electrochemical devices such as electrolysis cells, redox flow batteries and fuel cells.

[0004] Polyarylene polymer electrolytes comprising sulfonic acid functional groups are also known.

[0005] EP1935916A1 discloses polymers comprising recurring units of formulawherein A represents an amino group substituted with one or two hydrocarbon groups wherein the sum of number of carbon atoms of the hydrocarbon group or groups is 3 to 20, or a C3-C20 alkoxy group, R1 represents a hydrogen atom, a fluorine atom, a C1-C20 alkyl group, a C1-SSPU 2024 / 031C20 alkoxy group, a C6-C20 aryl group, a C6-C20 aryloxy group, a C2- C20 acyl group or a cyano group, and the C1-C20 alkyl group, the C1-C20 alkoxy group, the C6-C20 aryl group, the C6-C20 aryloxy group and the C2-C20 acyl group may be substituted with at least one substituent selected from the group consisting of a fluorine atom, a cyano group, a C1-C20 alkoxy group, a C6-C20 aryl group and a C6-C20 aryloxy group, and when multiple R1s exist, R1s may be the same groups or different groups, and the neighboring two R1s may be bonded to form a ring, m represents 1 or 2, and k represents 4-m which are obtained from the corresponding halides.

[0006] WO2014 / 208714A1 discloses a polyarylene polymer comprising recurring units of formula :in which R4is hydrogen, an alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and the substituents may be the same or different; r is 1 or 2, and d is 4-r. A represents OR5or N(R6)(R7), R5represents either hydrogen, an alkali metal, or an alkyl group having 1 to 20 carbon atoms, and R6and R7represent hydrogen or an alkyl group having 1 to 20 carbon atoms, either, and R6and R7may be the same or different. The recurring units are obtained from the corresponding dihalide monomers. The use of the polyarylene polymers in the preparation of electrolyte membranes is also disclosed.

[0007] According to the prior art disclosures, solvents that dissolve or swell the polymer are used in the preparation of liquid compositions used for the preparation of the membranes. For example, EP1721922 discloses that aprotic polar solvents can be used in the preparation of membranes.

[0008] EP2738194 (in the name of JSR Corporation) broadly discloses that a mixture of an aprotic polar solvent, in particular NMP, in an amount of 95 to 25 wt.% and of another solvent, such as methanol, in an amount from 5 to 75 wt.%, can be used to dissolve or swell the copolymer and reducingSSPU 2024 / 031 the viscosity of the composition, respectfully. However, the description of the examples provides no disclosure of the ratio of NMP and methanol used in the preparation of the electrolyte membrane.

[0009] Similarly, JP 4-949009 (Honda Motor Co., Ltd), WO 2014 / 157389 and WO 2015 / 005370 (JSR Corp, corresponding to US 2016 / 149250) broadly disclose solvent compositions comprising NMP and methanol, without however explicitly disclosing any specific ratio for such liquids.Summary of invention

[0010] The Applicant has now surprisingly found that the casting process is improved when membranes are cast from a liquid composition comprising a polyarylene polymer and a mixture of solvents comprising 70.0 wt% or more of at least one primary solvent selected notably from alcohol(s) and 30.0 wt% or less of an aprotic polar solvent.

[0011] Advantageously, the temperatures for the evaporation of the liquid phase after casting the membrane is reduced. Additionally, the membrane washing step to reduce the values of residual organic solvents in the membrane to meet the end-user requirements may be optional and - in any event - the amount of water needed is reduced.

[0012] The use of a liquid mixture comprising more than 70.0 wt% of an alcohol and less than 30.0 wt% of an aprotic polar solvent provides further advantages in the process for the manufacture of reinforced membranes in that the wetting of the reinforcement and its full impregnation are smoothly achieved. Additionally and surprisingly, the inventors have found that the viscosity of liquid compositions of the polyarylene polymer prepared with liquid mixtures comprising more than 70.0 wt.% of a primary solvent notably selected from alcohol(s) and less than 30.0 wt.% of an aprotic polar solvent have a much lower viscosity that liquid compositions comprising the same polymer but higher amounts of the aprotic polar solvent.

[0013] Furthermore, it was unexpectedly observed that the liquid composition of the invention has a very good ability to impregnate porous polymeric substrates throughout the thickness of the substrate, thus leading to theSSPU 2024 / 031 uniform distribution of Polymer (GP) through the reinforcement. Without being bound by any theory, this is considered to be provided by the good transparency of the reinforced membrane obtained with the liquid composition of the invention in comparison to the one obtained from the solutions of the prior art.Drawings

[0014] Figure 1 is a SEM image (taken at 5.0 kV with magnification 1 .8 k) of the cross-section of an ePTFE film coated with hydrocarbon ionomer using an NMP-based solution, prepared as disclosed in Comparative Example A.

[0015] Figure 2 is a SEM image (taken at 5.0 kV with magnification 2.0 k) of the cross-section of an ePTFE-reinforced film coated with hydrocarbon ionomer using an alcohol / NMP-based dispersion, prepared as disclosed in Example 4.Description of invention

[0016] In the present application:- any description, even though described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present disclosure;- where an element or component is said to be included in and / or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list;- the indeterminate article “a” in an expression like “a recurring unit” or “an alkyl alcohol” or “an aprotic polar solvent”, is intended to mean “one or more”, or “at least one” unless indicated otherwise;- the use of brackets “( )” before and after names of compounds, symbols or numbers, e.g. “Polymer (GP)”, has the mere purpose of betterSSPU 2024 / 031 distinguishing that name, symbol or number from the rest of the text; thus, said parentheses could also be omitted; and- any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges as well as the endpoints of the range and equivalents;- the proportions of recurring units in a polymer are given relative to the total moles of recurring units in the polymer;- the expression “percent by weight” (wt%) indicates the content of a specific component in a mixture, calculated as the ratio between the weight of the component and the total weight of the mixture. As used herein, the concentration of recurring units in “percent by mol” (mol%) refers to the concentration of a given type of recurring unit relative to the total number of recurring units in the polymer, unless explicitly stated otherwise;- the terminology “Cn-Cm” in reference to an organic group, wherein n and m are integers, respectively, indicates that the group may contain from n carbon atoms to m carbon atoms per group;- the expressions “proton conductive membrane” , “proton exchange membrane” , “polymer electrolyte membrane” and “electrolyte membrane” are used as synonyms and each of them is intended to indicate a semipermeable membrane designed to conduct protons, while acting as an electronic insulator and reactant barrier.

[0017] In a first object, the present invention relates to a liquid composition comprising(I) at least one polyarylene polymer [Polymer (GP)] comprising recurring units of formula (A) as defined hereafter:in whichR1is OY, with Y being H or an monovalent metal, or a C1-C20 alkoxy group, optionally substituted; p is 1 or 2;SSPU 2024 / 031 each Rx, independently of each other, is selected from the group consisting of a hydrogen atom, a fluorine atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C6-C20 aryl group, a C6-C20 aryloxy group, a C2- C20 acyl group or a cyano group, and the C1-C20 alkyl group, the C1-C20 alkoxy group, the C6-C20 aryl group, the C6-C20 aryloxy group and the C2-C20 acyl group may be substituted with at least one substituent selected from the group consisting of a fluorine atom, a cyano group, a C1-C20 alkoxy group, a C6-C20 aryl group and a C6-C20 aryloxy group, and when multiple Rxs exist the neighboring two Rxs may be bonded to form a ring; and(II) a liquid mixture comprising:- a primary solvent in an amount higher than 70.0 wt.% based on the total weight of said liquid mixture;- at least one secondary solvent in an amount of more than 1 .0 wt.% and less than 30.0 wt.% based on the total weight of said liquid mixture, said secondary solvent being selected from aprotic polar solvents; and- at least a third solvent in an amount from 0.0 wt.% and up to 30.0 wt.% based on the total weight of said liquid mixture, said third solvent being different from said primary solvent and from said secondary solvent.

[0018] A further object of the present invention is a process for the preparation of membranes comprising casting the liquid composition as defined above.

[0019] Preferably, said liquid composition is in the form of a dispersion.

[0020] In formula (A), p is preferably 1 .

[0021] Examples of the C1-C20 alkoxy group R1in formula (A) include linear, branched chain or cyclic C1-C20 alkoxy. Notable examples are for instance methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentyloxy, 2,2-methylpropoxy, cyclopentyloxy, n- hexyloxy, cyclo hexyl oxy, n-heptyloxy, 2-methylpentyloxy, n-octyloxy, 2- ethylhexyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy, n-dodecyloxy, n- tridecyloxy, n-tetradecyloxy, n-pentadecyloxy, n-hexadecyloxy, n- heptadecyloxy, n-octadecyloxy, n-nonadecyloxy and n-icosyloxy groups. Alkoxy group R1is preferably isobutoxy, 2,2-dimethylpropoxy or cyclohexyloxy. Alkoxy group R1is more preferably 2,2-dimethylpropoxy.SSPU 2024 / 031

[0022] R1in formula (A) can be OY wherein Y can be H or a monovalent metal. Suitable examples of monovalent metals are for instance alkaline metal, such as Li, Na, K, Rb, Cs. Other examples are transition metals such as Ag, Cu. Y is preferably hydrogen.

[0023] Each Rx, independently of each other, is selected from the group consisting of a hydrogen atom, a fluorine atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C6-C20 aryl group, a C6-C20 aryloxy group, a C2- C20 acyl group or a cyano group. Rxis preferably hydrogen.

[0024] Polymer (GP) may consist of one or more recurring units of formula (A) or it may comprise further recurring units.

[0025] Polymer (GP) may advantageously comprise, in addition to recurring units of formula (A), also recurring units of formula (B):in which each Ry, independently of each other, is selected from the group consisting of a fluorine atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C6-C20 aryl group, a C6-C20 aryloxy group, a C2-C30 acyl group or a cyano group, and the C1-C20 alkyl group, the C1-C20 alkoxy group, the C6-C20 aryl group, the C6-C20 aryloxy group and the C2-C20 acyl group may be substituted with at least one substituent selected from the group consisting of a fluorine atom, a cyano group, a C1-C20 alkoxy group, a C6-C20 aryl group and a C6-C20 aryloxy group, and when multiple Rys exist the neighboring two Rys may be bonded to form a ring, and q is 0 or an integer from 1 to 4.

[0026] In formula (B) q may be 0, 1 or 2; preferably 0 or 1 .

[0027] In formula (B) each Rymay be selected from the group consisting of a cyano group or a C2-C20 acyl group.

[0028] The C2-C30 acyl group may advantageously be an aromatic acyl group, preferably a group of formula -C(O)Ar wherein Ar is a C6-C20 aryl group which may be substituted with at least one selected from the groupSSPU 2024 / 031 consisting of a fluorine atom, a cyano group, a C1-C20 alkoxy group and a C6-C20 aryloxy group. Preferably Ar is phenyl, 1 -naphthyl, 2-naphthyl, 3- phenanthryl and 2-anthryl. More preferably Ar is phenyl.

[0029] One or more than one recurring unit of formula (B), different from one another, may be present in Polymer (GP).

[0030] Polymer (GP) may additionally comprise recurring units of formula (C):in whichRz1and Rz2, independently of each other, is selected from the group consisting of a fluorine atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C6-C20 aryl group, a C6-C20 aryloxy group, a C2-C20 acyl group or a cyano group, and the C1-C20 alkyl group, the C1-C20 alkoxy group, the C6-C20 aryl group, the C6-C20 aryloxy group and the C2-C20 acyl group may be substituted with at least one substituent selected from the group consisting of a fluorine atom, a cyano group, a C1-C20 alkoxy group, a C6-C20 aryl group and a C6-C20 aryloxy group, and when multiple RZ1and Rz2exist the neighboring ones may be bonded to form a ring; r and s are, independently of each other, an integer from 1 to 4; and Z is selected from the group consisting of an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, 2,2 isopropylidene group, 2,2 hexafluoroisopropylidene group.

[0031] In Polymer (GP) the amount of recurring units of formula (A) is from 0.1 to 90.0 mol% with respect to the total amount of recurring units in the polymer. The amount of recurring units of formula (A) is generally from 5.0 to 70.0 mol%, from 10.0 to 65.0 mol%, even from 25.0 to 60.0 mol%, from 35.0 to 55.0 mol%. The remainder of the units in Polymer (GP) may consist of one or more recurring units of formula (B) or of one or more recurring units of formula (B) and (C).SSPU 2024 / 031

[0032] The bonds connecting recurring units of formula (A) and / or (B) and / or (C) in Polymer (GP) may have an ortho, meta or para configuration. Preferably a meta and / or para configuration.

[0033] Polymer (GP) may conveniently consist of:- recurring units of formula (1):in which R1is as defined in formula (A);- recurring units of formula (2):in which R2is -C(O)Ar and Ar is a C6-C20 aryl group which may be substituted with at least one selected from the group consisting of a fluorine atom, a cyano group, a C1-C20 alkoxy group and a C6-C20 aryloxy group; preferably Ar is phenyl, 1-naphthyl, 2-naphthyl, 3- phenanthryl and 2-anthryl; more preferably Ar is phenyl; and- optionally recurring units of formula (3):in which A is either H or CN.

[0034] Polymer (GP) can be synthesized by known methods, such as those disclosed in EP1935916A1 , US20140154610A1 and WO2014208714A1 .

[0035] Polymer (GP) may be prepared by polymerizing a dihalo compound (I) that gives the structural unit (A) and optionally a compound (II) that gives the structural unit (B) and / or a compound (III) that gives the structural unit (C):SSPU 2024 / 031whereinRx, R1, p, Ry, q, Rz1and Rz2, Z are as defined above and each X is independently selected from the group consisting of halogens, mesylate, tosylate or triflate. Preferably, X is chlorine.

[0036] The polymerization is carried out preferably in the presence of a catalyst. Any catalyst for the polymerization of aromatic dihalide compounds may be used.

[0037] Typically, Polymer (GP) can be produced by polymerizing a monomer composition comprising the compounds (I) and optionally (II) and / or (III) in the presence of a nickel compound. Examples of the nickel compound include a zerovalent nickel compound such as bis(cyclooctadiene)- nickel(0), (ethylene)bis(triphenylphosphine)nickel(0) and tetrakis(triphenyl- phosphine)nickel(O), and a divalent nickel compound such as a nickel halide (e.g. nickel fluoride, nickel chloride, nickel bromide, nickel iodide etc.), bis(triphenylphosphine)nickel chloride, nickel carboxylate (e.g. nickel formate, nickel acetate etc.), nickel sulfate, nickel carbonate, nickel nitrate, nickel acetylacetonate and (dimethoxyethane)nickel chloride. Nickel chloride and nickel bromide are preferable.

[0038] The polymerization reaction is preferably conducted in the presence of the nickel compound and a nitrogen-containing or phosphorous-containing ligand. Examples of the nitrogen-containing ligands include 1 ,10-phenan- throline, methylenebisoxazoline and N,N'-tetramethylethylenediamine. Examples of the phosphorus-containing ligand include triphenylphosphine, tri(2-methyl)phenylphosphine, tri(3-methyl)phenylphosphine,SSPU 2024 / 031 tri(4-methyl)phenylphosphine, 1 ,5-cyclooctadiene, 1 ,3-bis(diphenyl- phosphino)propane.

[0039] The catalyst system may also include a reducing agent. Examples of the reducing agent include iron, zinc, manganese, aluminum, magnesium, sodium, and calcium. Zinc, magnesium, and manganese are preferable.

[0040] Examples of the salt other than transition metal salts that is employable in the catalyst system of the present invention include sodium compounds such as sodium fluoride, sodium chloride, sodium bromide, sodium iodide and sodium sulfate; potassium compounds such as potassium fluoride, potassium chloride, potassium bromide, potassium iodide and potassium sulfate; and ammonium compounds such as tetraethylammonium fluoride, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide and tetraethylammonium sulfate. Of these, sodium bromide, sodium iodide, potassium iodide, potassium bromide, tetraethylammonium bromide, and tetraethylammonium iodide are preferred.

[0041] The polymerization is carried out preferably in the presence of a polymerization solvent. Examples of the polymerization solvent include tetrahydrofuran, cyclohexanone, dimethyl sulfoxide, N,N-dimethyl- formamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, y-butyro- lactone and y-butyrolactam.

[0042] The polymerization reaction may be conducted in an atmosphere of an inert gas, such as nitrogen gas.

[0043] The polymerization is preferably carried out at a temperature from 0 to 200°C, more preferably 50 to 80° C. The polymerization time is typically 0.5 to 100 hours, preferably 1 to 40 hours.

[0044] After the completion of the polymerization reaction, Polymer (GP) can be isolated using known polymer isolation techniques. In an embodiment, Polymer (GP) is precipitated by mixing a solvent in which Polymer (GP) is poorly soluble with the reaction mixture.

[0045] Polymer (GP) precipitated from the reaction mixture is then separated by filtration. In an alternative embodiment, droplets of the reaction mixture are dropped, for instance by means of a nozzle, in a precipitation bath containing a solvent in which Polymer (GP) is poorly soluble. The solidSSPU 2024 / 031 particles that form are then recovered from the bath by decantation, filtration or any other known technique. Examples of the solvent in which the Polymer (GP) is insoluble or poorly soluble include water and acetone.

[0046] The precipitated polyarylene polymer may then be washed to remove any traces of the catalyst system, and other additives, and then dried.

[0047] To obtain the sulfonic acid ester as sulfonic acid groups -SOsY, with Y being H or a monovalent cation, the polyarylene polymer may undergo a thermal treatment or a chemical treatment, such a hydrolysis with an acid or an alkali or reaction with an alkaline halide. The conversion is preferably performed by means of a thermal treatment in the absence of any chemical treatment. The expression “chemical treatment” means hydrolysis with an acid or an alkali or reaction with an alkaline halide.

[0048] The thermal treatment typically comprises the step of heating Polymer (GP) to a temperature of 100 to 200°C comprises holding the polyarylene polymer at a temperature in the 100 to 200°C range for a time sufficient to achieve the conversion of the sulfonic acid ester groups into sulfonic acid groups. The heating step is generally performed for a time of 0.1 to 20.0 hours, typically a time of 1.0 to 15.0 hours, even 1.0 to 10.0 hours.

[0049] The completion of the conversion can be determined using conventional analytical means, such as1H NMR.

[0050] The ion exchange capacity of the polyarylene polymer can be controlled by changing the type, the use ratio and the combination of recurring units in the polymer. Ion-exchange capacity (IEC) refers to the total number of active sites or functional groups in a polymer that are responsible for ion exchange. In the present specification the ion exchange capacity (IEC) is defined as the number of milligrams equivalents of ions that may be exchanged per gram of dry resin.

[0051] The molar amount of recurring units of formula (A) and optionally recurring units of formula (B) and / or (C) in Polymer (GP) are selected to provide a polyarylene polymer having sulfonic acid groups (-SO3H) with an ion exchange capacity of 1 .00 to 5.50 meq / g, preferably 1 .50 to 4.50 meq / g, still more preferably 2.00 to 4.20 meq / g.

[0052] Preferably, the liquid composition comprises from about 1.0 to about 20.0 wt% of Polymer (GP) with respect to the total weight of the liquidSSPU 2024 / 031 composition, preferably from 1 .5 to 15.0 wt%, more preferably from 1 .5 to 10.0 wt%, even more preferably from 2.0 to 10.0 wt% and still more preferably from 2.5 to 8.5 wt%.

[0053] If the content of the Polymer (GP) is lower than the above range, the formation of a thickened membrane is difficult. On the other hand, if the content of Polymer (GP) exceeds the above range, film formation is difficult, and the resultant electrolyte membrane may fail to have a smooth surface.

[0054] Preferably, said primary solvent is in an amount of at least 72.0 wt.%, preferably at least 75.0 wt.%, more preferably at least 78.0 wt.%, even more preferably at least 78.5 wt.% and still more preferably at least 79.0 wt.% based on the total weight of said liquid mixture.

[0055] Preferably, said primary solvent is in an amount up to 98.9 wt.%, even more preferably up to 98.5 wt.% and still more preferably up to 98.0 wt.% based on the total weight of said liquid mixture.

[0056] Advantageously, said primary solvent is selected from solvents having dielectric constant (measured as relative permittivity at 20°C) higher than 15, boiling point lower than 110°C and surface tension lower than 40 mN / m (usually measured at 20°C, as per indication of the supplier).

[0057] Preferably, one solvent or a mixture of solvents can be used as the primary solvent in the liquid mixture.

[0058] Preferably, said primary solvent is selected from at least one protic solvent, more preferably from at least one alcohol.

[0059] Preferably said alcohol is an alkyl alcohol. More preferably, said alkyl alcohol is selected from alkyl alcohols having from 1 to 8 carbon atoms, preferably having from 1 to 4 carbon atoms.

[0060] Preferred examples of suitable alcohols are methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol, and mixtures thereof. More preferred alcohols are methanol, ethanol, n-propyl alcohol, and mixtures thereof.

[0061] Preferably, said secondary solvent is in an amount of more than 1.5 wt.%, more preferably at least 1 .75 wt.% and even more preferably at least 2.0 wt.% based on the total weight of the liquid mixture.SSPU 2024 / 031

[0062] Preferably, said secondary solvent is in an amount less than 28.0 wt.%, more preferably less than 25.0 wt.% and even more preferably less than 22.0 wt.% based on the total weight of the liquid mixture.

[0063] More preferably, said secondary solvent is in an amount from about 1 .8 wt.% and up to 21 .5 wt.%, even more preferably from about 2.0 wt.% and up to 20.0 wt.% based on the total weight of the liquid mixture.

[0064] Preferably, said secondary solvent is selected from at least one aprotic polar solvent.

[0065] Suitable aprotic polar solvents are selected from the group comprising, more preferably consisting of: N-methyl-2-pyrrolidone (NMP), N-ethyl-2- pyrrolidinone, N-butyl-2- pyrrolidone, N,N-dimethylformamide (DMF), 2- hydroxy-N,N-dimethyl- propanamide, y-butyrolactone, N,N- dimethylacetamide (DMAC), dimethylsulfoxide (DMSO), dimethylsulfone (DMSO2), methyl 5-(dimethylamino)-2-methyl-5- oxopentanoate, N- formylmorpholine, dihydrolevoglucosenone, dimethylurea, dimethylimidazolidinone, and acetonitrile; chlorine-based solvents such as dichloromethane, chloroform, 1 ,2-dichloroethane, chlorobenzene, and dichlorobenzene; alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol monoethyl ether; ketones such as acetone, methylethylketone, cyclohexanone, y-butyrolactone; ethers such as tetrahydrofuran, and 1 ,3- dioxane.

[0066] The aprotic polar solvent is more preferably selected from group consisting of N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidinone, N-butyl-2- pyrrolidone, N,N-dimethylformamide (DMF), y-butyrolactone, N,N- dimethylacetamide (DMAC), dimethylsulfoxide (DMSO), dimethylsulfone (DMSO2), methyl-5-(dimethylamino)-2-methyl-5- oxopentanoate, dihydrolevoglucosenone, dimethylurea, dimethyl- imidazolidinone, and acetonitrile; alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol monoethyl ether; ketones such as acetone, methylethylketone, cyclohexanone, y-butyrolactone; ethers such as tetrahydrofuran, and 1 ,3- dioxane.SSPU 2024 / 031

[0067] The aprotic polar solvent is even more preferably selected from group consisting of N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidinone, N- butyl-2- pyrrolidone, N,N-dimethylformamide (DMF), y-butyrolactone, N,N- dimethylacetamide (DMAC), dimethylsulfoxide (DMSO), dimethylsulfone (DMSO2), methyl-5-(dimethylamino)-2-methyl-5- oxopentanoate, cyclohexanone.

[0068] Advantageous liquid mixtures were found to comprise 80.0 to 98.0 wt% of the alkyl alcohol and 2.0 to 20.0 wt% of the aprotic polar solvent.

[0069] Very advantageous combinations of solvents are for instance:

[0070] The liquid mixture may comprise more than one aprotic polar solvent and / or more than one alkyl alcohol. Suitable combinations of aprotic polar solvents are for instance NMP and DMSO or NMP and DMSO2.

[0071] At least one third solvent can be present in the liquid mixture.

[0072] The amount of said third solvent is preferably at most 30.0 wt.%, more preferably at most 20.0 wt.%, even more preferably at most 15.0 wt.% or at most 10.0 wt.% or at most 7.0 wt.% or at most 5.0 wt.% or at most 2.5SSPU 2024 / 031 wt.% or at most 2.0 wt.% or at most 1 .5 wt.% or at most 1 .0 wt.% based on the total weight of the liquid mixture.

[0073] The amount of said third solvent is preferably at least 0.1 wt.%, more preferably at least 0.5 wt.%, even more preferably at least 1 .0 wt.% or at least 1 .5 wt.% based on the total weight of the liquid mixture.

[0074] Such at least one third solvent is preferably water.

[0075] The liquid composition of the invention may comprise further ingredients as known to the person skilled in the art.

[0076] Suitable further ingredients can be selected for example from stabilizers, chemical scavengers, recombination catalysts and the like.

[0077] Each of such further ingredients can be present in an amount below 1 wt.% based on the total weight of the liquid composition.

[0078] As said above, the liquid composition of the invention is preferably in the form of a dispersion.

[0079] Preferably, said dispersion comprises polymer (GP) in the form of powder or particles dispersed into said liquid mixture.

[0080] The dispersion may be prepared using known means for the dispersion of polymers in liquids.

[0081] Such dispersion is advantageously prepared from powders of Polymer (GP) having a particle size which is lower than 180 pm, preferably lower than 150 pm. Polymer (GP) with such particle size is preferably obtained by providing particles of Polymer (GP), grinding such particles and sieving.

[0082] The inventive dispersion comprising Polymer (GP) is used for the preparation of proton conductive membranes for electrolyzers, redox flow batteries and for fuel cells, as well as solid electrolytes for display elements, various kinds of sensors, signal transmission media, solid capacitors and the like. It may also be used in the preparation of ion exchange membranes or devices.

[0083] Surprisingly, it has been found that Polymer (GP) can be easily converted into a membrane from the dispersion disclosed above, said membrane being non porous.

[0084] A process for converting the film comprising Polymer (GP) into a polymer electrolyte membrane comprising Polymer (GP) is also an object of the invention.SSPU 2024 / 031

[0085] The expression “polymer electrolyte membrane” is used herein to refer to films of polymeric material characterized by ion exchange properties.

[0086] The polymer electrolyte membrane comprising polymer (GP) can be manufactured by a process including the step of applying the inventive dispersion on a substrate by a known coating method. Non-limiting examples of suitable coating methods are die coating, spray coating, knife coating, roll coating, roll-to-roll coating, slot die coating, spin coating and gravure coating.

[0087] Specifically, the process for the manufacture of the membrane of the invention comprises: applying the liquid composition onto a substrate, drying the applied liquid composition, thus obtaining a membrane, the resultant membrane being optionally peeled from the substrate. Thereby, the electrolyte membrane of the present invention can be obtained.

[0088] The substrate is not particularly limited. Preferred is a substrate composed of glass, more preferably borosilicate glass, or a thermoplastic resin, such as a polyethylene terephthalate (PET) film or polyimide (Kapton®) film, or a steel belt.

[0089] The electrolyte membrane comprising Polymer (GP) preferably has a dry membrane thickness of 5 to 100 pm, preferably 10 to 85 pm, more preferably 15 to 50 pm.

[0090] The electrolyte membrane of the present invention may be a single-layer membrane, or may be a multi-layer laminated membrane.

[0091] In the case of a laminated membrane, the thickness of each layer is arbitrarily determined: for example, the thickness may be such that one layer is thickened whereas another layer is thin. Each layer may be identical or different from one another.

[0092] The electrolyte membrane may comprise a reinforcement. Examples of known reinforcement are porous base materials or sheet-like fibrous materials.

[0093] The method for producing the reinforced solid polymer electrolyte membrane is not limited.

[0094] For example, such reinforced solid polymer electrolyte membrane is manufactured via a method in which a porous base material or a sheet-like fibrous material is impregnated with the inventive dispersion comprisingSSPU 2024 / 031 the Polymer (GP), or alternatively, via a method in which a membrane is formed from the liquid composition, preferably in the form of dispersion, beforehand, and the membrane is superposed on a porous base material or a sheet-like fibrous material, which are then hot pressed at a temperature below the melting point of the materials but high enough to ensure the bonding of the layers.

[0095] Preferably, the reinforced membrane is prepared by a process which comprises the step of impregnating a porous base material or a sheet-like fibrous material with the liquid composition, preferably in the form of dispersion, comprising the Polymer (GP).

[0096] The impregnated base material may be dried. Drying can be performed according to the methods known in the art, to achieve full drying or a partial drying.

[0097] The porous base material is preferably a material having a large number of pores or gaps penetrating in the thickness direction. Examples thereof include polymeric porous base materials and inorganic porous base materials composed of glass, metal oxides such as alumina or metals themselves.

[0098] The porous base material is preferably a polymeric porous base material. Specifically, preferred is a base material composed of at least one selected from the group consisting of polytetrafluoroethylene, polyolefins such as high molecular weight polyethylene, crosslinked polyethylene, polypropylene, polyimide, polyacrylonitrile, polyamideimide, polyetherimide, polyphenylene sulfide, polybenzimidazole, polyethersulfone, polyetherketone, polyetheretherketone, polyvinylidene fluoride. Preferably the porous base material comprises polytetrafluoroethylene.

[0099] Alternatively, the porous base material comprises at least one of polyethersulfone, polyetherketone, polyetheretherketone, high molecular weight polyethylene, crosslinked polyethylene, polypropylene, polyimide, polyacrylonitrile, polyamideimide, polyetherimide, polyphenylene sulfide, polybenzimidazole. More preferably polyethersulfone, polyetherketone, polyetheretherketone, polyamideimide, polyetherimide, polyphenylene sulfide and polybenzimidazole.SSPU 2024 / 031

[0100] At the end of the impregnation or casting step the liquid mixture is evaporated by drying. Drying is carried out at a temperature of 25°C to 190°C for 0.1 to 10 hours. The drying can be carried out preferably at a temperature of 60°C to 190°C, and can be continued preferably for 1 to 2 hours.

[0101] The drying may be carried out under an inert gas atmosphere such as a nitrogen atmosphere or under reduced pressure, as needed.

[0102] Optionally, after the drying, the membrane is soaked in water to remove any traces of the organic solvent present in the film obtained after the drying, so that the amount of a residual organic solvent in the resultant electrolyte membrane can be reduced.

[0103] The amount of the residual organic solvent in the electrolyte membrane thus obtained is usually not more than 0.5 wt%. Depending on soaking conditions, the amount of the residual organic solvent in the resultant membrane can be no more than 0.1 wt%.

[0104] After the pre-dried membrane or primary-dried membrane is soaked in water as described above, it is desirable that the soaked membrane is further dried at a temperature from 20°C to 100°C, conveniently at a temperature from 50°C to 80°C, for 10 to 180 minutes, preferably for 15 to 60 minutes, to obtain an electrolyte membrane.

[0105] The liquid composition of the present invention preferably comprises Polymer (GP) having a sulfonic acid ester group or a metal salt of a sulfonic acid, that is R1in formula (A) is OY, with Y being a monovalent metal or a C1-C20 alkoxy group. In such a case, the membrane formed by the above method may be subjected to an appropriate post-treatment such as hydrolysis and acid treatment, to produce the polymer electrolyte membrane of the present invention. Specifically, the above aromatic copolymer having a sulfonic acid ester group or an alkali metal salt of a sulfonic acid is formed into a membrane by such a method as described above, and the membrane thus formed is subjected to hydrolysis or acid treatment, whereby the polymer electrolyte membrane comprising the aromatic copolymer can be produced.

[0106] The reinforced polymer electrolyte membrane obtained from the dispersion of the invention is characterized by a reduced content of hot waterSSPU 2024 / 031 electrolyte extractable as well as good electrical conductivity (in particular through plane conductivity) and good mechanical stability.

[0107] The content of hot water electrolyte extractable, measured as detailed in the experimental section, is generally lower than 7 wt%, preferably lower than 5 wt%, at least comparable, if not better, than the values obtained with a membrane obtained by a standard polymer solution.

[0108] The through-plane conductivity is typically superior to the through-plane conductivity of a membrane obtained by a standard polymer solution.

[0109] The mechanical properties (and the consequent wet / dry cycling durability) of reinforced membranes obtained from the dispersion of the invention are much higher in comparison to the ones of a membrane obtained by a standard polymer solution.

[0110] The polymer electrolyte membrane may be used in a number of electrochemical devices, including but not limited to fuel cells, electrolyzers and redox flow batteries.

[0111] The polymer electrolyte membrane may also be used in filtration devices, such as microfiltration, ultrafiltration or reverse osmosis devices. The polymer electrolyte membrane may also be used as a gas separation membrane.

[0112] An object of the invention is thus also a device comprising the inventive membrane. The device may be one of a fuel cell, an electrolyzer, a redox flow battery, a filtration device or a gas separation device.

[0113] The embodiments above are intended to be illustrative and not limiting. Additional embodiments are within the inventive concepts. In addition, although the present invention is described with reference to particular embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention.

[0114] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0115] EXPERIMENTAL SECTIONSSPU 2024 / 031

[0116] The following methods were used.

[0117] Molecular weight determination Method by GPC analysis

[0118] Gel permeation chromatography (GPC) analyses were carried out using a Waters 2695 Separations Module and a Waters 2487 Dual Wavelength Absorbance detector with dimethylacetamide (0.1 M LiBr) as an eluent on two PLgel 5 pm MiniMIX-D columns (250 x 4.6 mm) and a PLgel 5 pm MiniMIX-D Guard (50 x 4.6 mm). An ultraviolet detector monitoring 270 nm was used to obtain the chromatogram. A flow rate of 0.3 ml / min and injection volume of 5 pL of a 0.2 w / v % solution in mobile phase was selected. Calibration was performed with 10 narrow molecular weight polystyrene standards (Peak molecular weight range: 371 ,000 to 580 g / mol).

[0119] In-plane conductivity

[0120] A Bekktech conductivity cell was used to measure in-plane proton conductivity (herein after referred to as ‘conductivity’) with a linear voltage sweep method using Ivium Vertex One potentiostat. All measurements took place at 80 °C in water.

[0121] Conductivity was calculated as inverse of resistivity according to the following equation:> 1 > L ° p R*W*T where L is the distance between electrodes, R is resistance, W is width of sample, and T is thickness of sample.

[0122] Ion Exchange Capacity

[0123] Ion exchange capacity was determined by first weighing the dry mass of the polymer. Subsequently, approximately 50 ml of 2M NaCI(aq) was added to the dry polymeric ionomer and allowed to stir at room temperature overnight. Finally, the solution was titrated with 0.1 M NaOH, using a standard 0.1 M NaOH(aq) titrant from ThermoFisher. A Mettler Toledo G20S Titrator was used to perform the titration, the resulting IEC was calculated using the equation below: (mmol SO3 / g polymer)SSPU 2024 / 031Ws = Weight of Polymer dispersion; C = Concentration of standard NaOH solution (mol / L); M = Moisture content; VD = Titre volume of NaOH used for the sample (mL)

[0125] Weight Loss For Leaching In Water

[0126] The percentage of weight loss, serving as a measure of membrane performance, was determined as follows. The process involved initially determining the dry weight of each membrane sample by heating it to 110°C until a stable weight is recorded. Following this, the dried sample underwent treatment in an autoclave at 120°C for 24 hours. Temperature and duration of the test were as disclosed by Yongqiang Li et at. in “Effects of melt flow index and equivalent weight on the dimensional stability and mechanical behavior of perfluorosulfonic acid ionomer membranes”, Journal of Power Sources, 478 (2020) 228734.

[0127] Once the treatment was complete, the autoclave was allowed to cool to below 50°C before the samples were removed. The dry weight of each treated sample was then measured by reheating it to 110°C until a stable weight is achieved.

[0128] To calculate the weight loss percentage for each membrane, the following formula was used:Weight toss % =

[0129] Viscosity Measurement

[0130] The viscosity of the polymer solution was determined and analyzed using a Brookfield DV2T Viscometer. Initially, the temperature of the polymer solution was assessed with a thermocouple. A spindle size that matches the sample cup and the volume of the polymer solution was chosen to enhance the precision of the measurements. The viscometer operated within a torque range of 10-100%, with a preference for torque readings of 50% or above. It was advisable to allow a stabilization period of 15-20 minutes before conducting measurements to ensure the viscometer achieves a steady state. The shear rate was ascertainable from the RPM range, typically spanning from 0.1 to 200rpm. The viscometer provided theSSPU 2024 / 031 measured viscosity, and the corresponding shear stress was calculable by multiplying this value by the shear rate.Shear rate ( 1 / s'j = RP'S " Shear Rate Constant ( SRCShear Stress = Viscosity * Shear Rate (1 / s)

[0131] Wet-Dry Cycling

[0132] Mylar subgaskets were applied to both sides of a 7 x 7 cm membrane sample and fixed between homemade gas diffusion electrodes [~0.3 mg / cm2 Pt loading on gas diffusion layer (SGL 28BC)] with a 25 cm2 active area. The assembly was placed into a Fuel Cell Technologies cell fixture. The fixture was connected to a custom Fuel Cell Testing Station with two cells in parallel per test.

[0133] One cell was fed with dry gases at the anode and cathode, while the other was fed with fully humidified gases. After 3.5 minutes, the flows were switched between the cells. When the OCV dropped below 0.5V (after showing a clear sudden drop, a symptom of failure), the sample was considered dead.

[0134] The test conditions were as follows:- Cathode: 135 nL / h air- Anode: 90 nL / h 5% H2 + 95% N2- Dew point temperature: 90°C- Cell temperature: 90°C- Preheater temperature: 95°C

[0135] Mechanical Testing:

[0136] The ASTM D882 protocol for stress-strain measurement was followed with sample width of 0.5 inches and gauge length of 4 inches with a test speed of 2 inches / minute for stress-strain measurement and 0.4inches / minute for modulus measurement. An average of three strips was measured for each ionomer membrane after equilibrating overnight at 20°C, 50% relative humidity (RH).

[0137] Through-Plane Conductivity:

[0138] A membrane electrode assembly was prepared with an active area of 12 cm2with a Pt / C electrode -0.3 mg / cm2Pt loading under hot pressing conditions of 160°C, 20 bar for 3 minutes and assembled into a cell withSSPU 2024 / 031Mylar gaskets and GDL Freudenberg H23C2. A Greenlight G40 equipped with a Baltic cell fixture with pneumatic compression was used to measure the through-plane resistance. The station was turned on and the cell was conditioned at 80°C. The cell was fed with hydrogen at a rate of 1000 seem at the anode and nitrogen at a rate of 2000sccm at the cathode.

[0139] At the start of the test, the flowing gas was adjusted to 30% RH, waiting for 1 hour to condition the cell. A voltage of 0.5V was then applied and, after 5 minutes, the electrochemical impedance spectroscopy (EIS) measurement was conducted. The frequency at the high frequency resistance (HFR) point (when the data trace intersects with the X-axis / real impedance at the highest frequencies measured on Nyquist’s plot) was identified. Then, a continuous impedance measurement was conducted at the identified frequency for 5 minutes.

[0140] The time-average resistance over 5 minutes at this frequency was recorded as the final value of resistance at 30% RH and the through-plane conductivity was calculated as described in the “in-plane conductivity” method above. This was then repeated at 50%RH, 80%RH and 100%RH.

[0141] Synthesis 1 : Polymer (GP-1)

[0142] Step 1 . To a 3-neck 250 mL round-bottom flask were added bis(triphenyl- phosphine)nickel chloride (6.73 g, 10.29 mmol), potassium iodide (10.25 g, 61.7 mmol), triphenylphosphine (16.19 g, 61.72 mmol), 2,5-dichloro benzophenone (68.58 g, 273.1 mmol), 2,6-dichlorobenzonitrile (5.22 g, 30.3 mmol), activated zinc dust (50.44 g, 771.5 mmol), and anhydrous N- methylpyrrolidone (460 mL) in a nitrogen atmosphere. The mixture was heated to 30 °C and held at temperature for 30 min before the addition of neopentyl-3,5-dichloro-benzenesulfonate (62.67 g, 210.9 mmol) at 37% solids in N-methylpyrrolidone (169 g). The mixture was then kept at 70 °C for 3 additional hours. The reaction media was diluted with N-methyl pyrrolidone (325 mL) and the mixture was filtered with Celite as a filter aid.

[0143] Step 2. The resulting reaction mixture was then transferred to a round bottomed flask, sparged with nitrogen for 30 minutes, and heated to 150 °C for 3 h. Then the polymer was coagulated into water (2000 g) and filtered. The polymer was subsequently washed 4 times with acetone, 7 times with aqueous 1 N sulfuric acid, and twice with water. The isolatedSSPU 2024 / 031 material was then dried under reduced pressure (300 torr - about 40 kPa) at 70°C for 18 hours, and afforded 72.25 g (84.8 % yield) of polymer GP-1 as a brown powder and having the following properties: Mw 199,400 g / mol I EC of 1.96 meq / g

[0144] Synthesis 2 : Polymer (GP-2)

[0145] Step 1 . To a 3-neck 250 mL round-bottom flask were added bis(triphenyl- phosphine)nickel chloride (6.58 g, 10.06 mmol), potassium iodide (10.02 g, 60.37 mmol), triphenylphosphine (15.83 g, 60.37 mmol), 2,5-dichloro benzophenone (57.92 g, 230.65 mmol), 2,6-dichlorobenzonitrile (4.41 g, 25.66 mmol), activated zinc dust (49.34 g, 754.6 mmol), and anhydrous N- methylpyrrolidone (428 mL) in a nitrogen atmosphere. The mixture was heated to 70 °C and held at temperature for 30 min before the addition of neopentyl-3,5-dichloro-benzenesulfonate (73.33 g, 246.75 mmol) at 37% solids in N-methylpyrrolidone (197.5 g). The mixture was then kept at 70 °C for 3 additional hours. The reaction media was diluted with N-methyl pyrrolidone (325 mL) and the mixture was filtered with Celite as a filter aid.

[0146] Step 2. was performed following the procedure described in Example 1 above.Polymer GP-2 as a brown powder was obtained having the following properties:MW = 211 ,000 g / mol I EC = 2.34 meq / g

[0147] Synthesis 3 : Polymer (GP-3)

[0148] Step 1 . To a 3-neck 250 mL round-bottom flask were added bis(triphenyl- phosphine)nickel chloride (6.44 g, 9.85 mmol), potassium iodide (9.81 g, 59.07 mmol), triphenylphosphine (15.49 g, 59.07 mmol), 2,5-dichloro benzophenone (47.73 g, 190.06 mmol), 2,6-dichlorobenzonitrile (3.63 g, 21.12 mmol), activated zinc dust (48.28 g, 738.4 mmol), and anhydrous N- methylpyrrolidone (416 mL) in a nitrogen atmosphere. The mixture was heated to 30 °C and held at temperature for 30 min before the addition of neopentyl-3,5-dichloro-benzenesulfonate (85.54 g, 281.09 mmol) at 36.9%SSPU 2024 / 031 solids in N-methylpyrrolidone (226.5 g). The mixture was then kept at 70 °C for 3 additional hours. The reaction media was diluted with N-methyl pyrrolidone (325 mL) and the mixture was filtered with Celite as a filter aid.

[0149] Step 2. was performed following the procedure described in Example 1 above.Polymer GP-3 as a brown powder was obtained having the following properties:MW = 195,300 g / mol I EC = 2.52 meq / g

[0150] General Procedure for the preparation of dispersions and membranes according to the present invention

[0151] The powder of the polymer prepared as described above was sieved using a 80 mesh stainless steel sieve.

[0152] Preparing the Dispersion. The alkyl alcohol and the aprotic polar solvent were added to the polymer powder. The mixture was stirred at high revolutions (1000-15000 rev / m) for 2-4 hours at 55°C until a uniform dispersion was achieved.

[0153] Casting a single layer unreinforced membrane. A glass substrate was placed on a preheated film applicator set at 40-80°C. The dispersion was placed on the glass substrate using a pipette. The membrane was cast at a speed of 5-40 mm / s, based on the desired thickness. Allow the membrane to dry until the alcohol evaporates completely, changing from milky to a light yellow color.

[0154] Casting a three-layer reinforced membrane. Cast a monolayer film as described but do not allow the alcohol to dry. Place the reinforcement material flat on the wet film that has been cast. Readjust the doctor blade height to the desired thickness to cast the second wet film layer and place it on the glass substrate, just above the reinforcement-wet film layer. Dispense the dispersion onto the substrate using a pipette. Cast another wet film layer at a speed of 5-40 mm / s. Set the temperature of the film applicator (room temperature to 100 °C) and allow the membrane to dry until the alcohol evaporates completely, changing from opaque milky to an almost transparent light yellow color.SSPU 2024 / 031[001551 Drying the Membrane. Preheat the oven to 100-150°C under continuous N2 flow and vacuum. Transfer the membrane with the substrate into the oven. Increase the temperature to 90% of the boiling point of the polar aprotic solvent used. Dry the membrane for 1 hour. Allow the membrane to cool to room temperature before peeling it off the substrate.

[0156] General Procedure for the preparation of compositions and membranes of comparison

[0157] The Polymer (GP-1) (5 g) was dissolved in 55 g of N-methylpyrrolidone at 80 °C. A portion of the prepared solution was cast on a glass plate substrate using a doctor blade then dried at 150 °C under nitrogen for 18 h. The membrane was soaked five times with deionized water for 5 min each then allowed to dry at room temperature before measuring conductivity.

[0158] Example 1

[0159] 16 g of liquid compositions having the solvent wt.% shown in the following Table 1 were prepared as follows.

[0160] To a glass vial were added 1 g of finely blended polymer powder (GP-1) prepared as disclosed above and a stir bar. The vial was then placed on a stir plate, set to 100 revolutions per minute, and heated to 50°C in the presence of the solvent composition detailed below. The total weight percentage of the polymer in each composition was maintained at 4 wt %.

[0161] The viscosities of the liquid compositions were measured and reported in the following Table 1 .Table 1(*) = of comparisonSSPU 2024 / 031

[0162] The lowest viscosity observed was at a 90 wt.% of ethanol concentration.This represented a drastic decrease in viscosity, with a percentage decrease of over 89% from the original 100 wt.% NMP solution, which highlighted the binary composition as optimal for applications requiring minimal viscosity.

[0163] Example 2A

[0164] The effect of liquid mixtures on the polymer membrane casting was evaluated as follows.

[0165] To a glass vial, 4 wt.% of polymer (GP-1 ) prepared as disclosed above was added with ethanol (EtOH) and NMP in the amounts provided in the following Table 2A.

[0166] The membranes were cast using the general procedure described above. Table 2A(*) = of comparison

[0167] It was not possible to prepare a solid membrane with mixture 5C*.

[0168] The above results showed that the conductivity of the resulting membranes increased with increasing EtOH content to the claimed amount.

[0169] Example 2B

[0170] The effect of liquid mixtures on the polymer membrane casting was evaluated as follows.SSPU 2024 / 031

[0171] To a glass vial, 4 wt.% of polymer (GP-2) prepared as disclosed above was added with ethanol (EtOH), NMP and water in the amounts provided in the following Table 2B.

[0172] The membranes were cast using the general procedure described above. Table 2B(*) = of comparison

[0173] Example 2C

[0174] The effect of liquid mixtures on the polymer membrane casting was evaluated as follows.

[0175] In a glass vial, 4 wt.% (1.5 g) of polymer (GP-2) prepared as disclosed above was added with 34.2g of ethanol (EtOH) and a mixture of NMP (0.9 g) and DMSO (0.9 g) or DMSO2 (0.9 g) in the amounts provided in the following Table 2C.

[0176] The membranes were cast using the general procedure described above. Table 2C(*) = of comparisonSSPU 2024 / 031

[0177] Example 3

[0178] The effect of primary and secondary solvent on the polymer membrane casting was evaluated as follows.

[0179] Ionomer compositions containing 4 wt.% of polymer (GP-1) were prepared using the combinations of solvents detailed in the following Table 3.

[0180] Membranes were cast using the general procedure described above.

[0181] The conductivity was evaluated using the method described above.Table 3(*) = of comparison

[0182] Comparative Example A - Preparation of NMP-solution-casted reinforced membranes

[0183] NMP-solution-casted reinforced membranes were prepared using (GP-1) according to the following method.SSPU 2024 / 031

[0184] Firstly, a 7.5 wt% solution of the ionomer was prepared using 1.125 g of ionomer and 13.875 g of NMP, dissolved overnight at 100°C. The solution was poured and spread on a glass sheet using a doctor blade at a height of 15 mil. A 4-micron thick sheet of ePTFE (Tetratex, Donaldson Company Inc.) was then placed flatly on top of the wet film that was cast. The ePTFE was sprayed with n-propanol (until it turned clear) to allow penetration of the NMP solution into ePTFE, which otherwise has a high contact angle on the ePTFE surface. The film was heated at 60°C for 15 minutes. Then, the ePTFE surface was sprayed again with n-propanol and immediately, another aliquot of ionomer dispersion was poured on top of the reinforcement and cast at 25 mil to form the three-layered film. The glass was maintained at 60°C for another 15 minutes before transferring to a preheated oven at 120°C under continuously flowing nitrogen. The oven temperature was ramped to 150°C and the film was dried for 2 hours. The dried composite film was removed from the oven and detached from the glass sheet after cooling.

[0185] Scanning electron microscopy of the film’s cross-section was used to visualize the penetration of the ionomer into the ePTFE, which was observed to be incomplete as many open pores remained visible.

[0186] The image obtained is shown in Figure 1 .

[0187] Example 4 - Preparation of reinforced membranes according to the invention

[0188] Dispersion-cast reinforced membranes were prepared using polymer (GP- 1).

[0189] Firstly, a 5 wt.% mixture of the ionomer was prepared using 0.75 g of ionomer, 1 .425 g of NMP (10wt.%), and 12.825 g of n-propanol (90wt.%), mixed overnight at room temperature. The dispersion of the hydrocarbon ionomer (5 wt.% dry content) in n-propanol / NMP (90:10 w / w) was poured and spread on a glass sheet using a doctor blade at a height of 15 mil. A 4-micron thick sheet of ePTFE (Tetratex, Donaldson Company Inc.) was then placed flatly on top of the wet film that was cast. The doctor blade’s height was readjusted to 25 mil to cast the second wet film layer. Another amount of ionomer dispersion was poured on top of the reinforcement andSSPU 2024 / 031 cast at the fixed height to form the three-layered film. The temperature of the film applicator was set 60 °C to allow a large amount of the n-propanol to evaporate. When the film turned fully transparent (approximately 20 minutes), it was dried in a preheated oven at 190°C under continuously flowing nitrogen for 1 hour. The dried composite film was removed from the oven and detached from the glass sheet after cooling.

[0190] Scanning electron microscopy of the film’s cross-section was used to visualize the penetration of the ionomer into the ePTFE, which was observed to be good as open pores were not visible in the ePTFE-ionomer region.

[0191] The image obtained is shown in Figure 2.

[0192] Young's modulus, tensile break strength and break strain of reinforced membranes obtained in Comparative Example A and in Example 4 were evaluated at 20°C on 50%RH of ePTFE-reinforced film coated with hydrocarbon ionomer. The results are reported in Table 4.Table 4 - Mechanical properties

[0193] The results showed that the mechanical properties obtained for the reinforced membranes obtained from the composition of the present invention are much higher compared with the composition of comparison.

[0194] Wet-dry cycling results of reinforced membranes obtained in Comparative Example A and in Example 4 were evaluated of ePTFE-reinforced film coated with hydrocarbon ionomer. The results are reported in Table 5.SSPU 2024 / 031Table 5 - Wet-Dry Cycling

[0195] The results showed that the long-term mechanical stability of the reinforced membranes obtained from the composition of the present invention is much higher compared with the composition of comparison. The large difference in the values for Comparative Example A (relative to the absolute values) is due to the extreme inhomogeneity of the prepared membrane.

[0196] Comparative Example B - Preparation of NMP-solution-casted reinforced membranes

[0197] NMP-solution-casted reinforced membranes were prepared using polymer (GP-1) according to the following method.

[0198] Firstly, a 7.5 wt% solution of the polymer was prepared using 1.125 g of polymer and 13.875 g of NMP, dissolved overnight at 100°C. The procedure was as disclosed in Comparative Example A.

[0199] Example 5 - Preparation of reinforced membranes according to the invention

[0200] Dispersion-cast reinforced membranes were prepared using polymer (GP- 3).

[0201] Firstly, a 5 wt.% mixture of the polymer was prepared using 0.75 g of polymer, 1.425 g of NMP (10 wt.%), and 12.825 g of ethanol (90 wt.%), mixed overnight at room temperature. The procedure was as disclosed in Example 4.SSPU 2024 / 031Table 6

Claims

SSPU 2024 / 031Claims1. A liquid composition comprising(I) at least one polyarylene polymer [Polymer (GP)] comprising recurring units of formula (A) as defined hereafter:in whichR1is OY, with Y being H or an monovalent metal, or a C1-C20 alkoxy group, optionally substituted; p is 1 or 2; each Rx, independently of each other, is selected from the group consisting of a hydrogen atom, a fluorine atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C6-C20 aryl group, a C6-C20 aryloxy group, a C2- C20 acyl group or a cyano group, and the C1-C20 alkyl group, the C1-C20 alkoxy group, the C6-C20 aryl group, the C6-C20 aryloxy group and the C2-C20 acyl group may be substituted with at least one substituent selected from the group consisting of a fluorine atom, a cyano group, a C1-C20 alkoxy group, a C6-C20 aryl group and a C6-C20 aryloxy group, and when multiple Rxs exist the neighboring two Rxs may be bonded to form a ring; and(II) a liquid mixture comprising:- a primary solvent in an amount higher than 70.0 wt.% based on the total weight of said liquid mixture;- at least one secondary solvent in an amount of more than 1 .0 wt.% and less than 30.0 wt.% based on the total weight of said liquid mixture, said secondary solvent being selected from aprotic polar solvents; and- at least a third solvent in an amount from 0.0 wt.% and up to 30.0 wt.% based on the total weight of said liquid mixture, said third solvent being different from said primary solvent and from said secondary solvent.SSPU 2024 / 0312. The liquid composition of Claim 1 , wherein Polymer (GP) comprises, in addition to recurring units of formula (A), recurring units of formula (B):in which each Ry, independently of each other, is selected from the group consisting of a fluorine atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C6-C20 aryl group, a C6-C20 aryloxy group, a C2-C30 acyl group or a cyano group, and the C1-C20 alkyl group, the C1-C20 alkoxy group, the C6-C20 aryl group, the C6-C20 aryloxy group and the C2-C20 acyl group may be substituted with at least one substituent selected from the group consisting of a fluorine atom, a cyano group, a C1-C20 alkoxy group, a C6-C20 aryl group and a C6-C20 aryloxy group, and when multiple Rys exist the neighboring two Rys may be bonded to form a ring, and q is 0 or an integer from 1 to 4.

3. The liquid composition of Claim 1 or 2, wherein Polymer (GP) comprises, in addition to recurring units of formula (A), and optionally to recurring units of formula (B), recurring units of formula (C):in whichRz1and Rz2, independently of each other, is selected from the group consisting of a fluorine atom, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C6-C20 aryl group, a C6-C20 aryloxy group, a C2-C20 acyl group or a cyano group, and the C1-C20 alkyl group, the C1-C20 alkoxy group, the C6-C20 aryl group, the C6-C20 aryloxy group and the C2-C20 acyl group may be substituted with at least one substituent selected from theSSPU 2024 / 031 group consisting of a fluorine atom, a cyano group, a C1-C20 alkoxy group, a C6-C20 aryl group and a C6-C20 aryloxy group, and when multiple RZ1and Rz2exist the neighboring ones may be bonded to form a ring; r and s are, independently of each other, an integer from 1 to 4; and Z is selected from the group consisting of an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, 2,2 isopropylidene group, 2,2 hexafluoroisopropylidene group.

4. The liquid composition according to any one of Claims 1 to 3, wherein the amount of recurring units of formula (A) is from 0.1 to 90.0 mol% with respect to the total amount of recurring units in Polymer (GP).

5. The liquid composition according to any one of Claims 1 to 4, wherein:- said primary solvent is in an amount of at least 72.0 wt.%, preferably at least 75.0 wt.%, based on the total weight of said liquid mixture, and up to 98.9 wt.%, even more preferably up to 98.5 wt.% based on the total weight of said liquid mixture; and / or- said secondary solvent is in an amount of more than 1 .5 wt.%, more preferably at least 1 .75 wt.% based on the total weight of said liquid mixture and less than 28.0 wt.%, preferably less than 25.0 wt.% based on the total weight of said liquid mixture.

6. The liquid composition according to any one of Claims 1 to 5, wherein said primary solvent is selected from solvents having dielectric constant (measured as relative permittivity at 20°C) higher than 15, boiling point lower than 110°C and surface tension lower than 40 mN / m (usually measured at 20°C, as per indication of the supplier).

7. The liquid composition according to any one of Claims 1 to 6, wherein said primary solvent is selected from at least one protic solvent, more preferably from at least one alcohol.

8. The liquid composition according to any one of Claims 1 to 5, wherein said secondary solvent is selected from at least one aprotic polar solvent,SSPU 2024 / 031 preferably selected in the group comprising: N-methyl-2-pyrrolidone (NMP), N- ethyl-2-pyrrolidinone, N-butyl-2- pyrrolidone, N,N-dimethylformamide (DMF), 2- hydroxy-N,N-dimethyl- propanamide, y-butyrolactone, N,N-dimethyl- acetamide (DMAC), dimethylsulfoxide (DMSO), dimethylsulfone (DMSO2), methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, N-formylmorpholine, dihydrolevoglucosenone, dimethylurea, dimethylimidazolidinone, and acetonitrile; chlorine-based solvents such as dichloromethane, chloroform, 1 ,2- dichloroethane, chlorobenzene, and dichlorobenzene; alkylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol monoethyl ether; ketones such as acetone, methylethylketone, cyclohexanone, y-butyrolactone; ethers such as tetrahydrofuran, and 1 ,3-dioxane.

9. The liquid composition according to any one of Claims 1 to 8, wherein said third solvent when present is in an amount of at most 20.0 wt.%, preferably at most 15.0 wt.% based on the total weight of the liquid mixture.

10. The liquid composition according to any one of Claims 1 to 9, wherein said polymer (GP) is in an amount from 1 .0 to 20.0 wt.% based on the total weight of the liquid composition.11 . The liquid composition according to any one of Claims 1 to 10, wherein said liquid composition is a dispersion comprising said polymer (GP) in the form of powder or particles dispersed into said liquid mixture.

12. A process for the manufacture of a membrane, preferably a proton conductive membrane, said process comprising:(i) providing a liquid composition according to any one of Claims 1 to 11 ,(ii) applying said liquid composition onto a substrate(iii) drying said liquid composition applied onto the substrate, thus obtaining a membrane; and(iv) optionally, separating said membrane from said substrate.SSPU 2024 / 03113. A proton conductive membrane suitable for use in electrolyzers, redox flow batteries and fuel cells; in solid electrolytes for display elements, sensors, signal transmission media, solid capacitors and the like; as a gas separation membrane; said proton conductive membrane being manufactured via the process of Claim 12.

14. The proton conductive membrane according to Claim 13, wherein said membrane is a single-layer membrane or a multi-layer laminated membrane.

15. The proton conductive membrane according to Claim 14, which is a multi-layer laminated membrane comprising a reinforcement selected from porous base materials, preferably selected from the group comprising polymeric porous base materials, glass, metal oxides such as alumina or metals; or sheet-like fibrous materials.

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