WO2024218155A1

WO2024218155A1 - Polyarylene polymers

Info

Publication number: WO2024218155A1
Application number: PCT/EP2024/060424
Authority: WO
Inventors: Nicolas TREAT; Bryan Benson; Eduardo Salvador SORIANO-JUAREZ; Wheeler LOVETT
Original assignee: Solvay Specialty Polymers Usa, Llc
Priority date: 2023-04-19
Filing date: 2024-04-17
Publication date: 2024-10-24

Abstract

A polyarylene polymer comprising sulfonic acid functional groups with high ion exchange capacity which provides films and membranes having good mechanical properties. The membranes are suitable for use as proton exchange membranes in electrochemical devices as well as filtration membranes.

Description

POLYARYLENE POLYMERS

Reference to related applications

This application claims priority to U.S. provisional application 63/460375 - filed April 19^th, 2023 - and to European patent application No. 23187888.5 - filed July 26^th, 2023 -, the whole content of each of these applications being incorporated herein by reference for all purposes.

Technical Field

[0001] The invention relates to polyarylene polymers having sulfonic acid functional groups, in particular it relates to polyarylene polymers having sulfonic acid functional groups with high ion exchange capacity and capable to provide films with good mechanical properties.

Background Art

[0002] 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. For example, perfluoroalkylsulfonic acid polymers have been used as a membrane material for fuel cells for several decades.

[0003] Polyarylene polymer electrolytes comprising sulfonic acid functional groups are also known. Polyarylene polymers comprising sulfonic acid functional groups can be obtained starting from monomers comprising sulfonate esters or sulfonamide functional groups.

[0004] EP1935916A1 discloses polymers comprising recurring units of formula

wherein 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 - 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 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.

[0005] LIS2014/0154610A1 discloses aromatic copolymers comprising a hydrophilic segment (A) and a hydrophobic segment (B), wherein the hydrophilic segment (A) comprises a structural unit having a proton conductive group, and the hydrophobic segment (B) comprises at least one structural unit selected from the group consisting of a structural unit which is a divalent structural unit having an aromatic ring and no proton conductive groups and having two bonding sites at the para-position of one ring included in the aromatic ring, and a divalent structural unit having a benzene ring. Notable example of structural units having a proton conducting group is for instance :

wherein Ar¹¹, Ar¹² and Ar¹³ are each independently a benzene ring, a condensed aromatic ring, or an aromatic group having a nitrogencontaining heterocyclic ring, which may be substituted by a halogen atom, a C1 -20 monovalent hydrocarbon group or a C1 -20 monovalent halogenated hydrocarbon group, Y and Z are each independently a direct bond, -O-, -S-, -CO-, -SO2-, -SO-, -(CH2)u-, -(CF2)u- where u is an integer of 1 to 10, -C(CH3)2-, or -C(CFS)2-, R¹⁷ is independently a direct bond, - O(CH2)_P-, -O(CF2)_P-, -(CH2)_P- or -(CF2)_P- where p is an integer of 1 to 12, R¹⁸ and R¹⁹ are each independently a hydrogen atom or a protective group, wherein at least one of all R¹⁸s and R¹⁹s which are contained in the structural unit (1 ) is a hydrogen atom, x¹ is independently an integer of 0 to 6, x² is an integer of 1 to 7, a is 0 or 1 , and b is an integer of 0 to 20.

[0006] WO2014/208714A1 discloses a polyarylene polymer comprising recurring units of formula :

in which R⁴ is 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 OR⁵ or N(R⁶)(R⁷), R⁵ represents either hydrogen, an alkali metal, or an alkyl group having 1 to 20 carbon atoms, and R⁶ and R⁷ represent hydrogen or an alkyl group having 1 to 20 carbon atoms, either, and R⁶ and R⁷ may 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. Among exemplified polymers, the following polyarylene polymer is disclosed in which the linking position of the phenylene unit comprising the sulfonic acid functionality to the main chain is situated at the para-position:

[0007] Polyarylene polymers in which the linking position of the phenylene unit comprising the sulfonic acid functionality to the main chain is situated at the para-position as those disclosed in WO2014/208714A1 are also disclosed in JP2016207609, JP2015038866 and JP2015165461 .

[0008] There is still the need to provide polyarylene polymers having sulfonic acid functional groups provided with high ion exchange capacities and which can be shaped into films having good mechanical properties. [0009] It has now been found that certain polymers whose recurring units consist of recurring units of formula (1 ):

and of recurring units of formula (2):

in which R² is -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; can be obtained which exhibit a high ion exchange capacity and can be shaped into membranes having good mechanical properties under the conditions of use. Without being bound by theory it is believed that polyarylene polymers in which the linking position of the phenylene unit comprising the sulfonic acid functionality to the main chain is situated at the meta-position may provide articles, such as films, with reduced brittleness.

Summary of invention

[0010] A first object of the invention is a polyarylene polymer, hereinafter referred to as Polymer (P), the recurring units of which consist of :

- recurring units of formula (1 ):

- recurring units of formula (2):

in which R² is -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, characterized in that it has an ion exchange capacity equal to or greater than 2.00 meq/g.

[0011 ] A further object of the invention is a method to obtain Polymer (P), said method comprising the step of heating a polymer consisting of recurring units of formula (3):

in which R¹ is a C1 -C20 alkoxy group, and

- recurring units of formula (4):

in which R² is -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; hereinafter referred to as Polymer (PP), at a temperature of 100 to 200°C to convert the C1 -C20 alkoxy group R¹ into a OH group. [0012] The invention further relates to films or membranes comprising Polymer (P) or Polymer (PP) as well as methods to prepare these membranes.

Description of invention

[0013] 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”, 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 (P)”, “Polymer (PP)”, etc... , has the mere purpose of better 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;

- 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; - as used herein, 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.

[0014] Polymer (P) consists of :

- recurring units of formula (1 ) in which R¹ is a C1 -C20 alkoxy group,

in which R² is -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.

[0015] For the sake of clarity, Polymer (P) is made of recurring units and end groups. End groups are groups that are at the very ends of a polymer chain. Polymer (P) therefore comprises recurring units and said recurring units consist of recurring units of formula (1 ) and recurring units of formula (2).

[0016] In formula (2), R² is -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 phenyl, 1 -naphthyl, 2-naphthyl, 3-phenanthryl and 2-anthryl. More preferably Ar is phenyl. For the avoidance of doubt, the expression “-C(O)Ar” identifies a ketone functional group.

[0017] Recurring units of formula (1 ) and recurring units of formula (2) may be randomly distributed in the polymer chain.

[0018] Alternatively, Polymer (P) may have a blocky structure. For instance, Polymer (P) may comprise blocks consisting of recurring units of formula (1 ) or (2) as well as blocks in which recurring units of formula (1 ) and (2) are randomly distributed.

[0019] The ion exchange capacity of Polymer (P) is equal to or greater than 2.00 meq/g as measured by ¹H NMR. The ion exchange capacity is typically from 2.00 to 5.50 meq/g, preferably from 2.00 to 5.00 meq/g, still more preferably from 2.20 to 4.40 meq/g. The method for the determination of the ion exchange capacity by ¹H NMR is detailed in the Examples.

[0020] Ion-exchange capacity (IEC) refers to the total number of active sites or functional groups in a polymer electrolyte membrane 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.

[0021 ] 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. In general, the increase in the amount of recurring units of formula (1 ) having a proton conductive group will lead to increased ion exchange capacity and increased proton conductivity, together with decreased water resistance.

[0022] The amount of recurring units of formula (1 ) is such that the polymer exhibits an ion exchange capacity equal to or greater than 2.00 meq/g. The amount of recurring units of formula (1 ) is generally from 20.0 to 90.0 mol% with respect to the total amount of recurring units in the polymer.

[0023] The amount of recurring units of formula (1 ) is generally from 25.0 to 90.0 mol%, from 30.0 to 85.0 mol%, from 35.0 to 85.0 mol%, even from 40.0 to 80.0 mol%, from 40.0 to 75.0 mol%. The remainder of the units in Polymer (P) consists of one or more recurring units of formula (2).

[0024] Polymer (P) has a weight average molecular weight, Mw, from 50000 to 500000, preferably 70000 to 400000, still more preferably 70000 to 300000. Molecular weight is measured by gel permeation chromatography utilizing polystyrene standards and dimethylacetamide as eluent as detailed in the Examples.

[0025] Polymer (P) may be in the form of a powder. The term “powder” is used herein to refer to a collection of solid particles with individual sizes. Advantageously the solid particles of Polymer (P) have an average size of nanometers to millimeters, preferably from microns to millimeters. The average particle size can be in the range of 50 microns to 20 mm, from 100 microns to 10 mm or even from 200 microns to 5 mm.

[0026] Particle size may be determined according to any method known in the art. For instance particle size can be determined by laser diffraction on a suspension in isopropanol of the collection of the particles. A MicroTrac S3500 laser diffraction instrument can be used, according to the manufacturers’ instructions or known methods.

[0027] The powder of Polymer (P) is typically free flowing.

[0028] Polymer (P) may also be in the form of a dispersion in a suitable solvent. Examples of suitable solvents are for instance polar organic solvents. Suitable solvents are for instance selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N- methyl-2-pyrrolidone.

[0029] Polymer (P) can be prepared starting from a precursor polymer, Polymer (PP), in which the sulfonic acid functional groups in recurring units of formula (1 ) are in the form of sulfonic acid ester groups.

[0030] Hence, Polymer (PP) comprises recurring units which consists of:

- recurring units of formula (3):

in which R¹ is a C1 -C20 alkoxy group, and recurring units of formula (2):

in which R² is as defined for Polymer (P). [0031 ] Polymer (PP) can be prepared by copolymerizing a compound (I) that gives the structural unit (3) and a compound (II) that gives the structural unit (2).

[0032] Notable non-limiting examples of compounds (I) are for instance those of formula (I’):

wherein R¹ is as defined above for the compounds of formula (1 ) and X¹ and X² are independently selected from the group consisting of halogens, mesylate, tosylate or triflate. Preferably, X¹ and X² are chlorine.

[0033] Similarly, compounds (II) are those of formula (II’):

wherein X³ and X⁴ are independently selected from the group consisting of halogens, mesylate, tosylate or triflate. Preferably, X³ and X⁴ are chlorine.

[0034] The polymerization is carried out preferably in the presence of a catalyst. Any catalyst for the polymerization of aromatic compounds may be used.

[0035] Typically, Polymer (PP) can be produced by polymerizing a monomer composition comprising compounds (I) and (II) 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(triphenylphosphine)nickel(0), 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.

[0036] 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- phenanthroline, methylenebisoxazoline and N,N'- tetramethylethylenediamine. Examples of the phosphorous-containing ligand include triphenylphosphine, tri(2-methyl)phenylphosphine, tri(3- methyl)phenylphosphine, tri(4-methyl)phenylphosphine, 1 ,5- cyclooctadiene, 1 ,3-bis(diphenylphosphino)propane. Triphenylphosphine and tri(2-methyl)phenylphosphine, are preferable. The ligand compounds may be used singly, or two or more kinds thereof may be used in combination.

[0037] 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. These reducing agents can be more activated by allowing these reducing agents to contact with acids such as organic acids.

[0038] 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. These may be used singly, or two or more kinds thereof may be used in combination.

[0039] Processes for the preparation of Polymer (PP) are disclosed in EP1935916A1 , US20140154610A1 and WO2014208714A1 .

[0040] The polymerization is carried out preferably in the presence of a polymerization solvent. [0041 ] Examples of the polymerization solvent include tetrahydrofuran, cyclohexanone, dimethyl sulfoxide, N,N-dimethylformamide, N,N- dimethylacetamide, N-methyl-2-pyrrolidone, y-butyrolactone and y- butyrolactam. Tetrahydrofuran, N,N-dimethylformamide, N,N- dimethylacetamide, and N-methyl-2-pyrrolidone are preferred.

[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; and the polymerization time is preferably 0.5 to 100 hours, preferably 1 to 40 hours.

[0044] After the completion of the polymerization reaction, Polymer (PP) can be isolated using known polymer isolation techniques. Polymer (PP) may be precipitated by mixing a solvent in which Polymer (PP) is poorly soluble with the reaction mixture, to precipitate the polyarylene polymer and separating the polyarylene polymer precipitated from the reaction mixture by filtration. Alternatively, droplets of the reaction mixture are dropped, for instance by means of a nozzle, in a precipitation bath containing a solvent in which Polymer (PP) is poorly soluble. Examples of the solvent in which Polymer (PP) is insoluble or poorly soluble include water, acetone, methanol, ethanol and acetonitrile. Water and acetone are preferable.

[0045] The precipitated polyarylene polymer may then be washed to remove any traces of the catalyst system, and other additives, and then dried.

[0046] Polymer (PP) may then be ground or sieved to obtain a powder comprising particles of the desired particle size as known to the person skilled in the art.

[0047] Polymer (PP) may be in the form of a powder. The solid particles of Polymer (PP) may have an average size of nanometers to millimeters, preferably from microns to millimeters. The average particle size can be in the range of 50 microns to 20 mm, from 100 microns to 10 mm or even from 200 microns to 5 mm.

[0048] The powder of Polymer (PP) is typically free flowing.

[0049] Polymer (PP) may also be in the form of a dispersion in a suitable solvent, in particular an organic solvent. Examples of suitable solvents, are for instance selected from the group consisting of tetrahydrofuran, cyclohexanone, dimethyl sulfoxide, N,N-dimethylformamide, N,N- dimethylacetamide, N-methyl-2-pyrrolidone, y-butyrolactone and y- butyrolactam, preferably dimethyl sulfoxide, N,N-dimethylformamide, N,N- dimethylacetamide, N-methyl-2-pyrrolidone.

[0050] It has surprisingly been found that conversion of the sulfonic acid ester groups in Polymer (PP) into sulfonic acid groups, to introduce proton conductive groups, can advantageously be obtained by means of a thermal treatment. Conversion of the sulfonic acid ester groups in Polymer (PP) into sulfonic acid groups takes place by heating Polymer (PP) at a temperature in the range of 100°C to 200°C. The conversion is achieved by thermal treatment in the absence of any chemical treatment, such as hydrolysis with an acid or an alkali or reaction with an alkaline halide.

[0051 ] The step of heating the Polymer (PP) to a temperature of 100 to 200°C comprises holding Polymer (PP) 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.

[0052] The process may be conveniently performed on Polymer (PP) in the form of powder. Powders may be heated to a temperature of 120 to 200 °C, more preferably from 140 to 160 °C.

[0053] Alternatively, Polymer (PP) may be dissolved in a suitable solvent and then submitted to the heat treating step at the temperature of 100 to 160°C. More preferably the polymer can be heated in solution at 130 to 160 °C, even more preferably at a temperature of 140 to 150 °C. The solution is free of any acid, alkali or alkaline halide such as Li Br.

[0054] Suitable solvents are for instance dimethyl sulfoxide, N,N- dimethylformamide, N,N-dimethylacetamide, or N-methyl-2-pyrrolidone.

[0055] Polymer (PP) may be submitted to the heat treating step at the temperature of 100 to 160°C, preferably 130 to 160°C, before being isolated from the reaction mixture, at the end of the polymerization process. The heat treating step is performed in the absence of any acid, alkali or alkaline halide. [0056] The completion of the conversion can be determined using conventional analytical means, such as ¹H NMR.

[0057] Polymer (P), because of its ion exchange capacity, may conveniently be used for the preparation of proton conductive membranes for electrolysers, 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.

[0058] Surprisingly, it has been found that Polymer (P) is characterized by good mechanical properties, in particular excellent elongation at break.

[0059] Accordingly, a further object of the invention is an article comprising Polymer (PP). Preferably the article is in the form of a film. The film generally has a thickness of 5 to 300 pm, preferably 10 to 150 pm, even 15 to 100 pm.

[0060] A process for converting the film comprising Polymer (P) into a polymer electrolyte membrane is also an object of the invention. The expression “polymer electrolyte membrane” is used herein to refer to films of polymeric material characterized by ion exchange properties, that is by the presence of ion exchange functional groups.

[0061] The process comprises the steps of: providing a film comprising Polymer (PP) and heating said film at a temperature in the range of 100 to 200°C to convert the sulfonic acid ester groups in Polymer (PP) into sulfonic acid groups.

[0062] Heating of the film of Polymer (PP) is typically performed at a temperature in the range from 140 to 160 °C. The heating step typically lasts for 1 .0 to 6.0 hours. The heating step can be conducted under vacuum or in the presence of superheated steam.

[0063] In an advantageous alternative embodiment, the process comprises preparing a solution of Polymer (PP) in an organic solvent, applying the solution on a substrate, and drying at a temperature in the range from 100 to 160 °C to obtain a film and at the same time convert the sulfonic acid ester groups in Polymer (PP) into sulfonic acid groups.

[0064] At the end of the processes described above, Polymer (PP) has been fully converted into Polymer (P) and the film comprises Polymer (P). [0065] In an alternative process for preparing a polymer electrolyte membrane comprising Polymer (P), Polymer (PP) is first submitted to a heat treatment step at a temperature in the range of 100 to 200°C to convert sulfonic acid ester groups into sulfonic acid groups, then it is shaped in the form of a film. The conversion is achieved by thermal treatment in the absence of any chemical treatment, such as hydrolysis with an acid or an alkali or reaction with an alkaline halide.

[0066] The polymer electrolyte membrane comprising polymer (P) or the film comprising Polymer (PP) can be produced by a process including the step of applying the composition prepared by mixing the polymer with a suitable solvent, on a substrate by a known method such as die coating, spray coating, knife coating, roll coating, spin coating and gravure coating.

[0067] Specifically, the composition is applied on a substrate, and the applied composition is dried to obtain a membrane, the resultant membrane being optionally peeled from the substrate. Thereby, the polymer electrolyte membrane of the present invention can be obtained.

[0068] The substrate is not particularly limited as long as being a substrate on which a common composition is applied, and for example, a substrate such as a plastic substrate and a metal substrate is used. Preferred is a substrate composed of a thermoplastic resin such as a polyethylene terephthalate (PET) film or polyimide (Kapton®) film or a steel belt.

[0069] The electrolyte membrane of the present invention preferably has a dry membrane thickness of 10 to 100 pm, preferably 15 to 85 pm, more preferably 20 to 80 pm and even 20 to 70 pm.

[0070] The electrolyte membrane of the present invention preferably has a hot water dissolution (after 24 hours at 120 °C in water) from 0.0 to 15.0 %. More preferably 0.0 to 5.0 %, particularly preferably 0.0 to 1 .0 %.

[0071] The electrolyte membrane of the present invention preferably has a conductivity, measured at 80°C in water, of 100 mS/cm or more, preferably of 150 mS/cm or more. The electrolyte membrane of the present invention preferably has a conductivity, measured at 80°C in water, of up to 500 mS/cm, preferably up to 650 mS/cm, even up to 800 mS/cm. [0072] The electrolyte membrane of the present invention preferably has a yield stress of 10 to 400 MPa, more preferably 20 to 400 MPa, particularly preferably 40 to 400 MPa.

[0073] The electrolyte membrane of the present invention preferably has an elongation at break of 4 to 400%, more preferably 4 to 100%, particularly preferably 4 to 50%. An electrolyte membrane having an elongation at break within the above range is excellent in membrane toughness.

[0074] The electrolyte membrane of the present invention may be a single-layer membrane, or may be a multi-layer laminated membrane.

[0075] In the case of the 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.

[0076] Where the laminated membrane is formed, the surface of the electrolyte membrane obtained by such methods as described above may be coated further with a composition containing the copolymer of the present invention by a known method such as die coating, spray coating, knife coating, slot die coating, roll coating, spin coating and gravure coating, the coating procedure optionally followed by drying. The film formed from a composition containing the copolymer of the present invention may be superposed on the film obtained by such methods as described above and be hot pressed.

[0077] Where the electrolyte membrane is manufactured, the use of a porous base material or a sheet-like fibrous material can produce a reinforced polymer electrolyte membrane.

[0078] Examples of the process for producing the reinforced solid polymer electrolyte membrane include a method in which a porous base material or a sheet-like fibrous material is impregnated with a composition comprising the copolymer of the present invention; a method in which the composition is applied on a porous base material or a sheet-like fibrous material; and a method in which a membrane is formed from the composition beforehand, and the membrane is superposed on a porous base material or a sheetlike fibrous material, and these are hot pressed. [0079] The porous base material is preferably a material having a large number of pores or gaps penetrating in the thickness direction. Examples thereof include organic porous base materials composed of various kinds of resins, and inorganic porous base materials composed of glass, metal oxides such as alumina or metals themselves.

[0080] The porous base material is preferably an organic porous base material. Specifically, preferred is a base material composed of at least one selected from the group consisting of polyolefins such as polytetrafluoroethylene, high molecular weight polyethylene, crosslinked polyethylene, polyethylene and polypropylene, polyimide, polyacrylonitrile, polyamideimide, polyetherimide, polyphenylene sulfide, polybenzamidazole, polyethersulfone, polyetherketone.

[0081] 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.

[0082] The polymer electrolyte membrane may also be used in filtration devices, such as microfiltration, ultrafiltration or reverse osmosis devices.

[0083] An object of the invention is thus also a filtration device comprising the inventive membrane as well as a method for filtering at least one fluid, said method comprising contacting said fluid with at least one membrane of the invention. Non limiting examples of suitable fluids are those selected from the group consisting of biologic solution, buffer solutions, oil/water emulsions, water, hydrocarbons.

[0084] The polymer electrolyte membrane may also be used as gas separation membrane.

[0085] A further object of the invention is thus a gas separation device comprising the inventive membrane as well as a method for separating at least one gas from a gaseous stream, said method comprising contacting said gaseous stream with at least one membrane of the invention.

[0086] 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 recognized that changes can be made in form and detail without departing from the spirit and scope of the invention.

[0087] EXAMPLES

[0088] Mechanical Testing:

[0089] Mechanical tests were performed on a Zwick Z010 tensile tester equipped with a 1 kN load cell and a climate chamber. Tests were performed at constant strain rate (50 mm/min), and from displacement and force signals engineering strain and stress were calculated. Tests were performed in an Espec SH-262 climate chamber, to control temperature and humidity during testing (20°C, 50 RH). Dog bone shaped samples (width 5 mm, gauge length 22 mm) were cut from the films using a die cutter.

[0090] Molecular weight determination Method - GPC

[0091 ] 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 urn minimixed - D columns (250 x 4.6 mm) and a PLgel 5um 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 I min and injection volume of 5 uL 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 I mol). The number average molecular weight Mn and weight average molecular weight Mw were reported.

[0092] Conductivity

[0093] A Bekktech conductivity cell is used to measure in-plane proton conductivity with a linear voltage sweep method using Ivium Vertex One potentiostat. All measurements take place at 80 °C in water. Conductivity was calculated as inverse of resistivity according to the following equation:

where L is the distance between electrodes, R is resistance, W is width of sample, and T is thickness of sample.

[0094] Ion Exchange Capacity [0095] Ion exchange capacity was determined using ¹H NMR (deuterated DMSO). The ratio of the integral from 7.8 - 8.2 ppm (3 H’s) and the integral from 6.75 - 7.8 ppm (8 H’s) is used to calculate the mol % of sulfonated comonomer. From this value, IEC is calculated.

[0096] Example 1 - Preparation of Polymer (PP)

[0097] To a 3-neck 250 mL round-bottom flask were added bis(triphenylphosphine)nickel chloride (1.447, 2.21 mmol), potassium iodide (2.204 g, 13.28 mmol), triphenylphosphine (3.483g, 13.28 mmol), activated zinc dust (10.85 g, 166 mmol), neopentyl-3,5-dichlorobenzenesulfonate (17.54 g, 59.04 mmol) at 37.02% solids in NMP and anhydrous N- methylpyrrolidinone (72 mL) in a nitrogen atmosphere. The mixture was heated to 50°C and held at temperature for 30 min prior to the addition of 2,5-dichlorobenzenophenone (14.825 g , 59.04 mmol) at 31.7% solids in N- methylpyrrolidone (46.6g). The mixture was then heated to 70°C and kept at temperature for 3 additional hours. The reaction media was diluted with 116 mL of N-methylpyrrolidone and the mixture was filtered with Celite as a filter aid and then coagulated into 1230 g of methanol and filtered. The resulting polymer washed a filtered with methanol containing 5% HCI four times prior to washing and filtering with methanol four times. The isolated material was then dried under reduced pressure (40 kPa) at 80°C for 18h, affording 21.875 g (91.15% yield) of Polymer (PP) as a beige powder.

[0098] Example 2 - Film of Polymer (PP)

[0099] Polymer (PP) of Example 1 (5.07g) was subsequently dissolved in 55.2 g of NMP at 80 °C. A portion of the prepared solution was cast on a glass plate substrate using a doctor blade and then dried at 80 °C for 1 h and then in an oven at 80 °C under nitrogen for 18h. The membrane was soaked five times in deionized water for 5 min each and then allowed to dry at room temperature before measuring conductivity.

[00100] Example 3 - Conversion of Polymer (P) from Polymer (PP) in powder form and casting into film

[00101 ] Polymer (PP) of Example 1 was placed in an oven at 160°C for 30 min. After heating, the sample was removed from the oven and subsequently dissolved into N-methylpyrrolidone to afford a 7% polymer solids solution. The solution was then cast at 80 °C on a glass plate using a doctor blade and then dried at 80 °C for 1 h and then in an oven at 120 °C under nitrogen for 18 h. The membrane was soaked five times in deionized water for 5 min each and then allowed to dry at room temperature before measuring conductivity. Conversion of the sulfonic acid ester groups into sulfonic acid groups is monitored using ¹H NMR (in deuterated DMSO).

[00102] Example 4 - Preparation of Polymer (P) from Polymer (PP) in solution and casting of Polymer (P) into a film

[00103] A portion of polymer solution from Example 2 was taken and heated at 140°C for three hours. The solution was then cast at 80 °C on a glass plate using a doctor blade and then dried at 80 °C for 1 h and then in an oven at 120°C under nitrogen for 18h. The membrane was soaked five times in deionized water for 5 min each and then allowed to dry at room temperature before measuring conductivity. Conversion of the sulfonic acid ester groups into sulfonic acid groups is monitored using ¹H NMR (in deuterated DMSO).

[00104] Example 5 - Conversion of Polymer (P) from Polymer (PP) during casting into a film

[00105] A portion of polymer solution from Example 2 was taken and then cast at 80 °C on a glass plate using a doctor blade and then placed in an oven at 120°C under nitrogen, which was ramped to 150 °C and held for at 150°C for 18 h. The membrane was soaked five times in deionized water for 5 min each and then allowed to dry at room temperature before measuring conductivity. Conversion of the sulfonic acid ester groups into sulfonic acid groups is monitored using ¹H NMR (in deuterated DMSO).

[00106] The ion exchange capacity (IEC) values measured in the films of Polymer (P) in Examples 3 to 5 as well as their conductivity measured at 80°C are reported in Table 1 . Table 1 also provides the IEC and conductivity of a film of Nation® 212 perfluorosulfonic acid as a reference.

Table 1

[00107] The results in Table 1 relating to Example 3 show that Polymer (PP) in powder form can be converted into Polymer (P) by heating. Polymer (PA) can then be shaped into a film which is characterized by high conductivity.

[00108] The conversion of Polymer (PP) into Polymer (P) can also be easily performed in solution (Example 4). The film obtained by casting of the solution also exhibits high conductivity and IEC.

[00109] Advantageously, as shown by Example 5 Polymer (PP) can be converted into Polymer (PA) during the process of making the film, in particular during the drying of the cast solution.

Claims

1. A polyarylene polymer the recurring units of which consist of : recurring units of formula (1 ):

- recurring units of formula (2):

in which R² is -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, said polyarylene polymer being characterized in that it has an ion exchange capacity equal to or greater than 2.00 meq/g.

2. The polyarylene polymer of claim 1 in which R² is -C(O)Ar and Ar is phenyl.

3. The polyarylene polymer of claim 1 or 2 in which the ion exchange capacity is from 2.00 meq/g to 5.50 meq/g.

4. The polyarylene polymer of any one of claims 1 to 3 in which the amount of recurring units of formula (1 ) is from 20 to 90 mol%, from 25 to 90 mol%, from 30.0 to 85.0 mol%, from 35.0 to 85.0 mol%, even from 40.0 to 80.0 mol%, from 40.0 to 75.0 mol% with respect to the total amount of recurring units in the polyarylene polymer.

5. The polyarylene polymer of any one of claims 1 to 4 which has a weight average molecular weight of from 50000 to 500000, preferably 70000 to 400000, more preferably 70000 to 300000, as measured by gel permeation chromatography.

6. The polyarylene polymer of any one of claims 1 to 5 which is in the form of a powder.

7. A dispersion comprising the polyarylene polymer of any one of claims 1 to 5 and a solvent, preferably a polar organic solvent.

8. The dispersion of claim 7 in which the solvent is selected from the group consisting of dimethyl sulfoxide, N,N-dimethylformamide, N,N- dimethylacetamide, N-methyl-2-pyrrolidone.

9. A film comprising the polyarylene polymer of any one of claims 1 to 5.

10. A polyarylene polymer the recurring units of which consists of:

- recurring units of formula (3): in which R¹ is a C1 -C20

, ■ recurring units of formula (2):

in which R² is as defined for Polymer (P), in which recurring units of formula (3) and of formula (2) are randomly distributed in the polymer chain.

11 . The polyarylene polymer of claim 10 which is in the form of a powder.

12. A dispersion comprising the polyarylene polymer of claim 10 and a solvent, preferably a polar organic solvent.

13. The dispersion of claim 12 in which the solvent is selected from the group consisting of tetrahydrofuran, cyclohexanone, dimethyl sulfoxide, N,N- dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, y- butyrolactone and Y-butyrolactam, preferably dimethyl sulfoxide, N,N- dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone.

14. A process of making the film of claim 9 comprising the steps of: dissolving the polyarylene polymer of any one of claims 1 to 5 in a solvent to obtain a dispersion or providing the dispersion of claim 7 or 8; casting said dispersion and drying.

15. A process of making the film of claim 9, said process comprising the steps of dissolving a polyarylene polymer the recurring units of which consists of:

- recurring units of formula (3):

in which R¹ is a C1 -C20 alkoxy group, and

- recurring units of formula (2):

in which R² is as defined for Polymer (P) in an organic solvent; and i) heating the solution to a temperature of 100°C to 200°C to convert the sulfonic acid ester groups into sulfonic acid groups, casting the solution to form a film and drying; or ii) casting the solution to form a film and heating the cast film to a temperature of 100°C to 200°C to convert the sulfonic acid ester groups into sulfonic acid groups and drying.

16. A process of making the film of claim 9, said process comprising the steps of providing a solution of the polyarylene polymer of claim 10 in a polar organic solvent, heating the solution at a temperature of 100 to 200°C to convert the sulfonic acid ester groups into sulfonic acid groups, recovering the polymer comprising sulfonic acid groups, forming a solution, casting the solution and drying.

17. The process of any one of claims 15 and 16 wherein the step of heating is performed for a time of 0.1 to 20.0 hours, of 1.0 to 15.0 hours, of 1.0 to 10.0 hours.

18. An electrochemical device, a filtration device or a gas separation device comprising the film of claim 9.