Random sulfonated poly (arylene ether sulfone) and sulfonated poly(arylene either ketone) membranes for proton exchange fuel cells

Abstract

Proton exchange membranes (PEMs) are disclosed, comprising a copolymer, the copolymer comprising: (i) a sulfonated monomer comprising a sulfonated (arylene ether sulfone), a sulfonated (arylene ether ketone), or a combination thereof, and (ii) a hydrophobic monomer, wherein the copolymer has a degree of sulfonation of about 10% to about 50%. The copolymer may further comprise (iii) a non-sulfonated monomer comprising a non-sulfonated arylene ether ketone, a non-sulfonated arylene ether sulfone, or a combination thereof. PEMs derived from such copolymers have proton conductivities on par with, or exceeding, NATION®, with lower methanol permeability, and higher normalized selectivity, when compared the NATION® 117. The PEMs are useful for preparing membrane electrode assemblies and fuel cells comprising the same.

Description

RANDOM SULFONATED POLY (ARYLENE ETHER SULFONE) AND SULFONATED POLY(ARYLENE EITHER KETONE) MEMBRANES FOR PROTON EXCHANGE FUEL CELLSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 603,255, filed November 28, 2023, the entire contents of which are incorporated herein by reference in their entirety for any and all purposes.BACKGROUND

[0002] Proton exchange membranes (PEMs) are a crucial aspect in developing direct methanol fuel cells (DMFC)s. PEMs serve a dual function: (1) as a conductor matrix for protons; and (2) as an insulator barrier for methanol. NAFION® is the conventional material of choice for PEMs. However, NAFION® has the drawbacks of a high methanol crossover, elevated price, and processability issues stemming from its nature as a perfluorinated polymer. Thus, there is great interest in development of electrolytic membranes with the ability to surpass the performance of NAFION® while overcoming the aforementioned disadvantages.SUMMARY

[0003] In one aspect, which may be combined with any other aspect or embodiment, the present disclosure relates to a proton exchange membrane (PEM), comprising: a copolymer, the copolymer comprising: (i) a sulfonated monomer comprising a sulfonated (arylene ether sulfone), a sulfonated (arylene ether ketone), or a combination thereof, and (ii) a hydrophobic monomer, wherein the copolymer has a degree of sulfonation of about 10% to about 50%. In some embodiments, the copolymer further comprises (iii) a non-sulfonated monomer comprising a non-sulfonated arylene ether ketone, a non-sulfonated arylene ether sulfone, or a combination thereof. In some embodiments, the copolymer is a random copolymer.

[0004] In some embodiments, the degree of sulfonation is about 20% to about 30%.

[0005] In some embodiments, the sulfonated monomer is a monomer derived from a sulfonated poly(arylene ether sulfone). In some embodiments, the sulfonated monomer comprises a sulfonated biphenyl sulfone. In some embodiments, the sulfonated monomer is a sulfonated poly(arylene ether ketone). In some embodiments, the sulfonated monomer comprises a monomer derived from a sulfonated benzophenone. In some embodiments, the sulfonated monomer is a monomer derived from 4,4’ -di chlorodiphenylsulfone, a monomer derived from 4,4’-dichlorobenzophenone, or a combination thereof.

[0006] In some embodiments, the hydrophobic monomer comprises a monomer unit derived from 2,2-bis(4-hydroxyphenyl) propane (BP A), a monomer unit derived from 4,4’- dihydroxyphenyl (BP), or a combination thereof. In some embodiments, the hydrophobic monomer comprises a monomer unit derived from BPA.

[0007] In some embodiments, the non-sulfonated arylene ether ketone is a benzophenone and the non-sulfonated arylene ether sulfone is a diphenyl sulfone.

[0008] In some embodiments, the average distance between sulfonic groups is less than or equal to 0.5 nm.

[0009] In some embodiments, the PEM has a proton conductivity at 50°C of 0.10 S cm'1or greater. In some embodiments, the PEM has a proton conductivity at 80°C of 0.15 S cm'1or greater. In some embodiments, the proton conductivity at 80°C is 0.20 S cm'1or greater.

[0010] In some embodiments, the PEM has an effective proton mobility at at 80°C of greater than 0.050 x 10'5cm2s'1V'1. In some embodiments, the PEM has a methanol permeability of less than or equal to 1.5 x 10'6cm2s'1.

[0011] In another aspect, which may be combined with any other aspect or embodiment, the present disclosure relates to a membrane electrode assembly (MEA), comprising: an anode; a cathode; and a PEM according to any of the embodiments disclosed herein, disposed between the anode and the cathode.

[0012] In another aspect, which may be combined with any other aspect or embodiment, the present disclosure relates to a fuel cell comprising: an electrochemical cell comprising a membrane electrode assembly, wherein the membrane electrode assembly comprises: an anode; a cathode; and a PEM according to any of the embodiments disclosed herein,disposed between the anode and the cathode. In some embodiments, the fuel cell is a direct methanol fuel cell.

[0013] Additional aspects and / or embodiments of the invention will be provided, without limitation, in the detailed description of the present technology set forth below. The following detailed description is exemplary and explanatory, but it is not intended to be limiting.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Various objects, aspects, features, and advantages of the disclosure will become more apparent and better understood by referring to the detailed description taken in conjunction with the accompanying figures.

[0015] FIG. 1 shows FTIR spectra of random sulfone and ketone 25% sulfonated polymers.

[0016] FIG. 2 shows a thermogravimetric analysis (TGA) plot (top) and derivative plot (bottom) for random sulfone and ketone 25% sulfonated polymers.

[0017] FIG. 3A is a plot of water uptake value (%) for random sulfone and ketone 25% sulfonated polymers.

[0018] FIG. 3B is a plot of ion exchange capacity (meq g'1) for random sulfone and ketone 25% sulfonated polymers.

[0019] FIG. 3C is a plot of water content ([H2O] / [ionic domain]) for random sulfone and ketone 25% sulfonated polymers.

[0020] FIG. 4 shows AFM images for: (A) SPAEK A 25 (25 pm); (B) SPAEK A 25 (100 nm); (C) SPAEA A 25 (25 pm); and (D) SPAES A 25 (100 nm).

[0021] FIG. 5 shows small angle x-ray scattering (SAXS) (top) and wide angle x-ray scattering (WAXS) (bottom) profiles for random sulfone and ketone 25% sulfonated polymers.

[0022] FIG. 6A is a plot of proton conductivities (S cm’1) at 50°C and 80°C for random sulfone and ketone 25% sulfonated polymers, compared to NAFION® 117. See Kang & Kim 2015.

[0023] FIG. 6B is a plot of methanol permeability (Pxieon,X106cm2 / s) for random sulfone and ketone 25% sulfonated polymers, compared to NAFION® 117. See Wang et al. 2011

[0024] FIG. 6C is a plot of effective proton mobility (geir, 10'5cmV-V1) at 50°C and 80°C for random sulfone and ketone 25% sulfonated polymers.

[0025] FIG. 6D is a plot of normalized selectivity at 50°C and 80°C, relative to NAFION® 117, for random sulfone and ketone 25% sulfonated polymers.

[0026] Reference will now be made in detail to some specific embodiments contemplated by the present disclosure. While various embodiments are described herein, it will be understood that it is not intended to limit the present technology to the described embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the technology as defined by the appended claims.DETAILED DESCRIPTION

[0027] Before the present disclosure is further described, it is to be understood that the disclosure is not limited to the particular embodiments set forth herein, and it is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.Definitions

[0028] The following terms are used throughout as defined below.

[0029] As used herein and in the appended claims, singular articles such as “a” and “an” and “the” and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential.

[0030] As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, “about” will mean up to plus or minus 10% of the particular term - for example, “about 10 wt.%” would be understood to mean “9 wt.% to 11 wt.%.” It is to be understood that when “about” precedes a term, the term is to be construed as disclosing “about” the term as well as the term without modification by “about” - for example, “about 10 wt.%” discloses “9 wt.% to 11 wt.%” as well as disclosing “10 wt.%.”

[0031] The phrase “and / or” as used in the present disclosure will be understood to mean any one of the recited members individually or a combination of any two or more thereof - for example, “A, B, and / or C” would mean “A, B, C, A and B, A and C, B and C, or the combination of A, B, and C.”

[0032] Generally, reference to a certain element such as hydrogen or H is meant to include all isotopes of that element. For example, if an R group is defined to include hydrogen or H, it also includes deuterium and tritium. Compounds comprising radioisotopes such as tritium, C14, P32and S35are thus within the scope of the present technology. Procedures forinserting such labels into the compounds of the present technology will be readily apparent to those skilled in the art based on the disclosure herein.

[0033] In general, “substituted” refers to an organic group as defined below (e.g., an alkyl group) in which one or more bonds to a hydrogen atom contained therein are replaced by a bond to non-hydrogen or non-carbon atoms. Substituted groups also include groups in which one or more bonds to a carbon(s) or hydrogen(s) atom are replaced by one or more bonds, including double or triple bonds, to a heteroatom. Thus, a substituted group is substituted with one or more substituents, unless otherwise specified. In some embodiments, a substituted group is substituted with 1, 2, 3, 4, 5, or 6 substituents.Examples of substituent groups include: halogens (z.e., F, Cl, Br, and I); hydroxyls; alkoxy, alkenoxy, aryloxy, aralkyloxy, heterocyclyl, heterocyclylalkyl, heterocyclyloxy, and heterocyclylalkoxy groups; carbonyls (oxo); carboxylates; esters; urethanes; oximes; hydroxylamines; alkoxyamines; aralkoxyamines; thiols; sulfides; sulfoxides; sulfones; sulfonyls; pentafluorosulfanyl (z.e., SFs), sulfonamides; amines; N-oxides; hydrazines; hydrazides; hydrazones; azides; amides; ureas; amidines; guanidines; enamines; imides; isocyanates; isothiocyanates; cyanates; thiocyanates; imines; nitro groups; and nitriles (z.e., CN).

[0034] Substituted ring groups such as substituted cycloalkyl, aryl, heterocyclyl, and heteroaryl groups also include rings and ring systems in which a bond to a hydrogen atom is replaced with a bond to a carbon atom. Therefore, substituted cycloalkyl, aryl, heterocyclyl and heteroaryl groups may also be substituted with substituted or unsubstituted alkyl, alkenyl, and alkynyl groups as defined below.

[0035] Alkyl groups include straight chain and branched chain alkyl groups having from 1 to 12 carbon atoms, and typically from 1 to 10 carbons or, in some embodiments, from 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Alkyl groups may be substituted or unsubstituted.Examples of straight chain alkyl groups include, but are not limited to, groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl groups. Examples of branched alkyl groups include, but are not limited to, isopropyl, iso-butyl, sec-butyl, tertbutyl, neopentyl, isopentyl, and 2,2-dimethylpropyl groups. Representative substituted alkyl groups may be substituted one or more times with substituents such as those listed above, and include without limitation haloalkyl (e.g., trifluoromethyl), hydroxyalkyl,thioalkyl, aminoalkyl, alkylaminoalkyl, dialkylaminoalkyl, alkoxyalkyl, carboxyalkyl, and the like.

[0036] Cycloalkyl groups include mono-, bi- or tricyclic alkyl groups having from 3 to 12 carbon atoms in the ring(s), or, in some embodiments, 3 to 10, 3 to 8, or 3 to 4, 5, or 6 carbon atoms. Cycloalkyl groups may be substituted or unsubstituted. Exemplary monocyclic cycloalkyl groups include, but not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. In some embodiments, the cycloalkyl group has 3 to 8 ring members, whereas in other embodiments the number of ring carbon atoms range from 3 to 5, 3 to 6, or 3 to 7. Bi- and tricyclic ring systems include both bridged cycloalkyl groups and fused rings, such as, but not limited to, bicyclo[2.1.1]hexane, adamantyl, decalinyl, and the like. Substituted cycloalkyl groups may be substituted one or more times with, non-hydrogen and non-carbon groups as defined above. However, substituted cycloalkyl groups also include rings that are substituted with straight or branched chain alkyl groups as defined above. Representative substituted cycloalkyl groups may be mono-substituted or substituted more than once, such as, but not limited to, 2,2-, 2,3-, 2,4- 2,5- or 2,6-disubstituted cyclohexyl groups, which may be substituted with substituents such as those listed above.

[0037] Cycloalkylalkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of an alkyl group is replaced with a bond to a cycloalkyl group as defined above. Cycloalkylalkyl groups may be substituted or unsubstituted. In some embodiments, cycloalkylalkyl groups have from 4 to 16 carbon atoms, 4 to 12 carbon atoms, and typically 4 to 10 carbon atoms. Substituted cycloalkylalkyl groups may be substituted at the alkyl, the cycloalkyl or both the alkyl and cycloalkyl portions of the group. Representative substituted cycloalkylalkyl groups may be mono-substituted or substituted more than once, such as, but not limited to, mono-, di- or tri-substituted with substituents such as those listed above.

[0038] Alkenyl groups include straight and branched chain alkyl groups as defined above, except that at least one double bond exists between two carbon atoms. Alkenyl groups may be substituted or unsubstituted. Alkenyl groups have from 2 to 12 carbon atoms, and typically from 2 to 10 carbons or, in some embodiments, from 2 to 8, 2 to 6, or 2 to 4 carbon atoms. In some embodiments, the alkenyl group has one, two, or three carboncarbon double bonds. Examples include, but are not limited to vinyl, allyl, -CH=CH(CH3),-CH=C(CH3)2, -C(CH3)=CH2, -C(CH3)=CH(CH3), -C(CH2CH3)=CH2, among others.Representative substituted alkenyl groups may be mono-substituted or substituted more than once, such as, but not limited to, mono-, di- or tri-substituted with substituents such as those listed above.

[0039] Cycloalkenyl groups include cycloalkyl groups as defined above, having at least one double bond between two carbon atoms. Cycloalkenyl groups may be substituted or unsubstituted. In some embodiments the cycloalkenyl group may have one, two or three double bonds but does not include aromatic compounds. Cycloalkenyl groups have from 4 to 14 carbon atoms, or, in some embodiments, 5 to 14 carbon atoms, 5 to 10 carbon atoms, or even 5, 6, 7, or 8 carbon atoms. Examples of cycloalkenyl groups include cyclohexenyl, cyclopentenyl, cyclohexadienyl, cyclobutadienyl, and cyclopentadienyl.

[0040] Cycloalkenylalkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of the alkyl group is replaced with a bond to a cycloalkenyl group as defined above. Cycloalkenylalkyl groups may be substituted or unsubstituted. Substituted cycloalkenylalkyl groups may be substituted at the alkyl, the cycloalkenyl or both the alkyl and cycloalkenyl portions of the group. Representative substituted cycloalkenylalkyl groups may be substituted one or more times with substituents such as those listed above.

[0041] Alkynyl groups include straight and branched chain alkyl groups as defined above, except that at least one triple bond exists between two carbon atoms. Alkynyl groups may be substituted or unsubstituted. Alkynyl groups have from 2 to 12 carbon atoms, and typically from 2 to 10 carbons or, in some embodiments, from 2 to 8, 2 to 6, or 2 to 4 carbon atoms. In some embodiments, the alkynyl group has one, two, or three carboncarbon triple bonds. Examples include, but are not limited to -C=CH, -C=CCH3, -CH2C=CCH3, and -C=CCH2CH(CH2CH3)2, among others. Representative substituted alkynyl groups may be mono-substituted or substituted more than once, such as, but not limited to, mono-, di- or tri-substituted with substituents such as those listed above.

[0042] Aryl groups are cyclic aromatic hydrocarbons that do not contain heteroatoms. Aryl groups herein include monocyclic, bicyclic and tricyclic ring systems. Aryl groups may be substituted or unsubstituted. Thus, aryl groups include, but are not limited to, phenyl, azulenyl, heptalenyl, biphenyl, fluorenyl, phenanthrenyl, anthracenyl, indenyl, indanyl, pentalenyl, and naphthyl groups. In some embodiments, aryl groups contain 6-14 carbons,and in others from 6 to 12 or even 6-10 carbon atoms in the ring portions of the groups. In some embodiments, the aryl groups are phenyl or naphthyl. The phrase “aryl groups” includes groups containing fused rings, such as fused aromatic-aliphatic ring systems (e.g., indanyl, tetrahydronaphthyl, and the like). Representative substituted aryl groups may be mono-substituted (e.g., tolyl) or substituted more than once. For example, monosubstituted aryl groups include, but are not limited to, 2-, 3-, 4-, 5-, or 6-substituted phenyl or naphthyl groups, which may be substituted with substituents such as those listed above.

[0043] Aralkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of an alkyl group is replaced with a bond to an aryl group as defined above. Aralkyl groups may be substituted or unsubstituted. In some embodiments, aralkyl groups contain 7 to 16 carbon atoms, 7 to 14 carbon atoms, or 7 to 10 carbon atoms. Substituted aralkyl groups may be substituted at the alkyl, the aryl or both the alkyl and aryl portions of the group. Representative aralkyl groups include but are not limited to benzyl and phenethyl groups and fused (cycloalkylaryl)alkyl groups such as 4-indanylethyl. Representative substituted aralkyl groups may be substituted one or more times with substituents such as those listed above.

[0044] Heterocyclyl groups include aromatic (also referred to as heteroaryl) and nonaromatic ring compounds containing 3 or more ring members, of which one or more is a heteroatom such as, but not limited to, N, O, and S. Heterocyclyl groups may be substituted or unsubstituted. In some embodiments, the heterocyclyl group contains 1, 2, 3 or 4 heteroatoms. In some embodiments, heterocyclyl groups include mono-, bi- and tricyclic rings having 3 to 16 ring members, whereas other such groups have 3 to 6, 3 to 10, 3 to 12, or 3 to 14 ring members. Heterocyclyl groups encompass aromatic, partially unsaturated and saturated ring systems, such as, for example, imidazolyl, imidazolinyl and imidazolidinyl groups. The phrase “heterocyclyl group” includes fused ring species including those comprising fused aromatic and non-aromatic groups, such as, for example, benzotri azolyl, 2,3-dihydrobenzo[l,4]dioxinyl, and benzo[l,3]dioxolyl. The phrase also includes bridged polycyclic ring systems containing a heteroatom such as, but not limited to, quinuclidyl. The phrase includes heterocyclyl groups that have other groups, such as alkyl, oxo or halo groups, bonded to one of the ring members, referred to as “substituted heterocyclyl groups”. Heterocyclyl groups include, but are not limited to, aziridinyl, azetidinyl, pyrrolidinyl, imidazolidinyl, pyrazolidinyl, thiazolidinyl, tetrahydrothiophenyl,tetrahydrofuranyl, dioxolyl, furanyl, thiophenyl, pyrrolyl, pyrrolinyl, imidazolyl, imidazolinyl, pyrazolyl, pyrazolinyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, thiazolinyl, isothiazolyl, thiadiazolyl, oxadiazolyl, piperidyl, piperazinyl, morpholinyl, thiomorpholinyl, tetrahydropyranyl, tetrahydrothiopyranyl, oxathiane, dioxyl, dithianyl, pyranyl, pyridyl, pyrimidinyl, pyridazinyl, pyrazinyl, triazinyl, dihydropyridyl, dihydrodithiinyl, dihydrodithionyl, homopiperazinyl, quinuclidyl, indolyl, indolinyl, isoindolyl,azaindolyl (pyrrolopyridyl), indazolyl, indolizinyl, benzotri azolyl, benzimidazolyl, benzofuranyl, benzothiophenyl, benzthiazolyl, benzoxadi azolyl, benzoxazinyl, benzodithiinyl, benzoxathiinyl, benzothiazinyl, benzoxazolyl, benzothiazolyl, benzothiadi azolyl, benzo [1,3] dioxolyl, pyrazolopyridyl, imidazopyridyl (azabenzimidazolyl), tri azol opyridyl, isoxazolopyridyl, purinyl, xanthinyl, adeninyl, guaninyl, quinolinyl, isoquinolinyl, quinolizinyl, quinoxalinyl, quinazolinyl, cinnolinyl, phthalazinyl, naphthyridinyl, pteridinyl, thianaphthyl, dihydrobenzothiazinyl, dihydrobenzofuranyl, dihydroindolyl, dihydrobenzodioxinyl, tetrahydroindolyl, tetrahydroindazolyl, tetrahydrobenzimidazolyl, tetrahydrobenzotriazolyl, tetrahydropyrrolopyridyl, tetrahydropyrazolopyridyl, tetrahydroimidazopyridyl, tetrahydrotriazolopyridyl, and tetrahydroquinolinyl groups. Representative substituted heterocyclyl groups may be mono-substituted or substituted more than once, such as, but not limited to, pyridyl or morpholinyl groups, which are 2-, 3-, 4-, 5-, or 6-substituted, or disubstituted with various substituents such as those listed above.

[0045] Heteroaryl groups are aromatic ring compounds containing 5 or more ring members, of which, one or more is a heteroatom such as, but not limited to, N, O, and S. Heteroaryl groups may be substituted or unsubstituted. Heteroaryl groups include, but are not limited to, groups such as pyrrolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, thiophenyl, benzothiophenyl, furanyl, benzofuranyl, indolyl, azaindolyl (pyrrolopyridinyl), indazolyl, benzimidazolyl, imidazopyridinyl (azabenzimidazolyl), pyrazolopyridinyl, triazolopyridinyl, benzotri azolyl, benzoxazolyl, benzothiazolyl, benzothiadi azolyl, imidazopyridinyl, isoxazolopyridinyl, thianaphthyl, purinyl, xanthinyl, adeninyl, guaninyl, quinolinyl, isoquinolinyl, tetrahydroquinolinyl, quinoxalinyl, and quinazolinyl groups. Heteroaryl groups include fused ring compounds in which all rings are aromatic such as indolyl groups and include fused ring compounds in which only one of the rings is aromatic, such as 2,3-dihydroindolyl groups. Representative substituted heteroaryl groups may be substituted one or more times with various substituents such as those listed above.

[0046] Heterocyclylalkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of an alkyl group is replaced with a bond to a heterocyclyl group as defined above. Heterocyclylalkyl groups may be substituted or un substituted. Substituted heterocyclylalkyl groups may be substituted at the alkyl, the heterocyclyl or both the alkyl and heterocyclyl portions of the group. Representative heterocyclyl alkyl groups include, but are not limited to, morpholin-4-yl-ethyl, furan-2-yl-methyl, imidazol-4-yl-methyl, pyri din-3 -yl-m ethyl, tetrahydrofuran-2-yl-ethyl, and indol-2-yl-propyl. Representative substituted heterocyclylalkyl groups may be substituted one or more times with substituents such as those listed above.

[0047] Heteroaralkyl groups are alkyl groups as defined above in which a hydrogen or carbon bond of an alkyl group is replaced with a bond to a heteroaryl group as defined above. Heteroaralkyl groups may be substituted or unsubstituted. Substituted heteroaralkyl groups may be substituted at the alkyl, the heteroaryl or both the alkyl and heteroaryl portions of the group. Representative substituted heteroaralkyl groups may be substituted one or more times with substituents such as those listed above.

[0048] Groups described herein having two or more points of attachment (i.e., divalent, trivalent, or polyvalent) within the compound of the present technology are designated by use of the suffix, “ene.” For example, divalent alkyl groups are alkylene groups, divalent aryl groups are arylene groups, divalent heteroaryl groups are divalent heteroarylene groups, and so forth. Substituted groups having a single point of attachment to the compound of the present technology are not referred to using the “ene” designation. Thus, e.g., chloroethyl is not referred to herein as chloroethylene.

[0049] Alkoxy groups are hydroxyl groups (-OH) in which the bond to the hydrogen atom is replaced by a bond to a carbon atom of a substituted or unsubstituted alkyl group as defined above. Alkoxy groups may be substituted or unsubstituted. Examples of linear alkoxy groups include but are not limited to methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, and the like. Examples of branched alkoxy groups include but are not limited to isopropoxy, sec-butoxy, tert-butoxy, isopentoxy, isohexoxy, and the like. Examples of cycloalkoxy groups include but are not limited to cyclopropyloxy, cyclobutyloxy,cyclopentyloxy, cyclohexyloxy, and the like. Representative substituted alkoxy groups may be substituted one or more times with substituents such as those listed above.

[0050] The terms “alkanoyl” and “alkanoyloxy” as used herein can refer, respectively, to - C(O)-alkyl groups and -O-C(O)-alkyl groups, each containing 2-5 carbon atoms. Similarly, “aryloyl” and “aryloyloxy” refer to -C(O)-aryl groups and -O-C(O)-aryl groups.

[0051] The terms "aryloxy" and “arylalkoxy” refer to, respectively, a substituted or unsubstituted aryl group bonded to an oxygen atom and a substituted or unsubstituted aralkyl group bonded to the oxygen atom at the alkyl. Examples include but are not limited to phenoxy, naphthyloxy, and benzyloxy. Representative substituted aryloxy and arylalkoxy groups may be substituted one or more times with substituents such as those listed above.

[0052] The term “carboxylate” as used herein refers to a -COOH group.

[0053] The term “ester” as used herein refers to -COOR70and -C(O)O-G groups. R70is a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl, aralkyl, heterocyclylalkyl or heterocyclyl group as defined herein. G is a carboxylate protecting group. Carboxylate protecting groups are well known to one of ordinary skill in the art. An extensive list of protecting groups for the carboxylate group functionality may be found in Protective Groups in Organic Synthesis, Greene, T.W.; Wuts, P. G. M., John Wiley & Sons, New York, NY, (3rd Edition, 1999) which can be added or removed using the procedures set forth therein and which is hereby incorporated by reference in its entirety and for any and all purposes as if fully set forth herein.

[0054] The term “amide” (or “amido”) includes C- and N-amide groups, i.e., -C(O)NR71R72, and -NR71C(O)R72groups, respectively. R71and R72are independently hydrogen, or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclylalkyl or heterocyclyl group as defined herein. Amido groups therefore include but are not limited to carbamoyl groups (-C(O)NH2) and formamide groups (-NHC(O)H). In some embodiments, the amide is -NR71C(O)-(CI-5 alkyl) and the group is termed "carbonylamino," and in others the amide is -NHC(O)-alkyl and the group is termed "alkanoylamino."

[0055] The term “nitrile” or “cyano” as used herein refers to the -CN group.

[0056] Urethane groups include N- and O-urethane groups, i.e., -NR73C(O)OR74and -OC(O)NR73R74groups, respectively. R73and R74are independently a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclylalkyl, or heterocyclyl group as defined herein. R73may also be H.

[0057] The term “amine” (or “amino”) as used herein refers to -NR75R76groups, wherein R75and R76are independently hydrogen, or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclylalkyl or heterocyclyl group as defined herein. In some embodiments, the amine is alkylamino, dialkylamino, arylamino, or alkylarylamino. In other embodiments, the amine is NH2, methylamino, dimethylamino, ethylamino, diethylamino, propylamino, isopropylamino, phenylamino, or benzylamino.

[0058] The term “sulfonamido” includes S- and N-sulfonamide groups, i.e., -SO2NR78R79and -NR78SO2R79groups, respectively. R78and R79are independently hydrogen, or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclylalkyl, or heterocyclyl group as defined herein. Sulfonamido groups therefore include but are not limited to sulfamoyl groups (-SO2NH2). In some embodiments herein, the sulfonamido is -NHSCh-alkyl and is referred to as the "alkylsulfonylamino" group.

[0059] The term “thiol” refers to -SH groups, while “sulfides” include -SR80groups, “sulfoxides” include -S(O)R81groups, “sulfones” include -SO2R82groups, and “sulfonyls” include -SO2OR83. R80, R81, R82, and R83are each independently a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein. In some embodiments the sulfide is an alkylthio group, -S-alkyl.

[0060] The term “urea” refers to -NR84-C(O)-NR85R86groups. R84, R85, and R86groups are independently hydrogen, or a substituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, aryl, aralkyl, heterocyclyl, or heterocyclylalkyl group as defined herein.

[0061] The term “amidine” refers to -C(NR87)NR88R89and -NR87C(NR88)R89, wherein R87, R88, and R89are each independently hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein.

[0062] The term “guanidine” refers to -NR90C(NR91)NR92R93, wherein R90, R91, R92and R93are each independently hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein.

[0063] The term “enamine” refers to -C(R94)=C(R95)NR96R97and -NR94C(R95)=C(R96)R97, wherein R94, R95, R96and R97are each independently hydrogen, a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein.

[0064] The term “halogen” or “halo” as used herein refers to bromine, chlorine, fluorine, or iodine. In some embodiments, the halogen is fluorine. In other embodiments, the halogen is chlorine or bromine.

[0065] The term “hydroxyl” as used herein can refer to -OH or its ionized form, -O . A “hydroxyalkyl” group is a hydroxyl-substituted alkyl group, such as HO-CH2-.

[0066] The term “imide” refers to -C(O)NR98C(O)R", wherein R98and R" are each independently hydrogen, or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein.

[0067] The term “imine” refers to -CR100(NR101) and -N(CR100R101) groups, wherein R100and R101are each independently hydrogen or a substituted or unsubstituted alkyl, cycloalkyl, alkenyl, alkynyl, aryl aralkyl, heterocyclyl or heterocyclylalkyl group as defined herein, with the proviso that R100and R101are not both simultaneously hydrogen.

[0068] The term “nitro” as used herein refers to an -NO2 group.

[0069] The term “trifluorom ethyl” as used herein refers to -CF3.

[0070] The term “trifluorom ethoxy” as used herein refers to -OCF3.

[0071] The term “azido” refers to -N3.

[0072] The term “trialkyl ammonium” refers to a -N(alkyl)s group. A trialkylammonium group is positively charged and thus typically has an associated anion, such as halogen anion.

[0073] The term “isocyano” refers to -NC.

[0074] The term “isothiocyano” refers to -NCS.

[0075] The term “pentafluorosulfanyl” refers to -SFs.

[0076] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 atoms refers to groups having 1, 2, or 3 atoms. Similarly, a group having 1-5 atoms refers to groups having 1, 2, 3, 4, or 5 atoms, and so forth.

[0077] As understood by one of ordinary skill in the art, “molecular weight” (also known as “relative molar mass”) is a dimensionless quantity but is converted to molar mass by multiplying by 1 gram / mole or by multiplying by 1 Da - for example, a compound with a weight-average molecular weight of 5,000 has a weight-average molar mass of 5,000 g / mol and a weight-average molar mass of 5,000 Da.

[0078] As understood by one of ordinary skill in the art, “degree of sulfonation” (“DoS”) (expressed as a fraction or as a percentage) refers to the total moles of sulfonated monomeric units used in the polymerization to produce the copolymer, divided by the total moles of all monomeric units used in the polymerization to produce the copolymer. For instance, in a copolymer with a degree of sulfonation of 25%, the sulfonated monomers constitute 25% of all monomer units used in the polymerization to produce the copolymer.Polymers for Proton Exchange Membranes (PEMs)

[0079] Among the materials proposed as candidates for NAFION® replacement, the poly(arylene ether) polymers stand out for their high thermal stability, good oxidative stability, and elevated solvent resistance. Although these properties make them attractivePEM candidates, their protonic conductivity is considered low. Sulfonation is one method to overcome this problem and impart more conductivity to the poly(arylene) ethers. Sulfonation can be accomplished pre-polymerization (“pre-sulfonation”) or postpolymerization (“post-sulfonation”). Post-sulfonation methods commonly require attaching sulfonic groups to specific sites on the polymer structure using a sulfonating agent.However, it is somewhat difficult to control the extent of sulfonation using this method, due to steric effects (e.g., hindrance) surrounding the desired sulfonation location or potential side reactions. For example, some post-sulfonation processes for it has been poly(arylene ether sulfones) (PAES) are attended by undesired reactions, such as chain scissoring and crosslinking.

[0080] Compared with the post-sulfonation approach, pre-sulfonation (z.e., direct sulfonation) may be a more effective way to obtain specific polymers with controlled sulfonation levels by reacting sulfonated monomers with other desired moieties. This method may permit realization of conductivities equal to or greater than 0.1 S cm'1at 50°C, which is considered a standard value for NAFION®. Further, direction sulfation may enable PEMs with high conductivities rivaling or exceeding that of NAFION® while having low methanol permeabilities, which is highly desirable for direct methanol fuel cell (DMFC) applications.Sulfonated Poly(arylene) Ether Polymers

[0081] Proton exchange membranes (PEMs) according to the present disclosure comprise a copolymer, the copolymer comprising (i) a sulfonated monomer comprising a sulfonated (arylene ether sulfone), a sulfonated (arylene ether ketone), or a combination thereof, and (ii) a hydrophobic monomer.

[0082] In some embodiments, the sulfonated monomer comprising a sulfonated (arylene ether sulfone) or sulfonated (arylene ether ketone) has the structure of Formula (I):wherein X1is C=O or O=S=O. In some embodiments, X1is C=O. In some embodiments, X1is O=S=O. In some embodiments, the sulfonated monomer comprises a compound of Formula (I), wherein X1is C=O, O=S=O, or a combination thereof. In some embodiments, the sulfonated monomer comprises a sulfonated diphenyl sulfone, a sulfonated benzophenone, or a combination thereof. In some embodiments, the sulfonated monomer unit comprises a sulfonated monomer unit derived from 4,4’ -di chlorodiphenyl sulfone (DCDPS), 4,4’ -di chlorobenzophenone (DCBP), or a combination thereof. In some embodiments, the sulfonated monomer comprises a compound similar to a compound of Formula (I) but for having sulfonate groups at different positions on the phenyl rings than shown in Formula (I).

[0083] In some embodiments, the hydrophobic monomer comprises a compound ofFormula (II):(II), wherein R1and R2are each independently hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, alkenyl, cycloalkenyl, cycloalkenylalkyl, alkynyl, aryl, aralkyl, heterocyclyl, heteroaryl, heterocyclylalkyl, or heteroaralkyl. In some embodiments, R1and R2are each independently methyl. In some embodiments, the hydrophobic monomer unit comprises a monomer unit derived from bisphenol A (BP A), 4,4’-dihydroxyphenyl (BP), or a combination thereof.

[0084] In some embodiments, the hydrophobic monomer is a monomer derived from a variant of a biphenyl compound (e.g., hexestrol, di ethylstilbestrol (DES), dienestrol, or any combination thereof).

[0085] In some embodiments, the copolymer further comprises a non-sulfonated monomer comprising a non-sulfonated arylene ether ketone, a non-sulfonated arylene ether sulfone, or a combination thereof. In some embodiments, the non-sulfonated monomer has a structure according to Formula (III):(HI), wherein X2is C=0 or O=S=O. In some embodiments, X2is C=O. In some embodiments, X2is O=S=O. In some embodiments, the non-sulfonated monomer comprises a sulfonated diphenyl sulfone, a non-sulfonated benzophenone, or a combination thereof. In some embodiments, the non-sulfonated monomer unit comprises a monomer unit derived from 4,4’-dichlorodiphenyl sulfone (DCDPS), 4,4’-dichlorobenzophenone (DCBP), or a combination thereof.

[0086] In some embodiments, the copolymer has a degree of sulfonation of less than or equal to 90%, less than or equal to 88%, less than or equal to 85%, less than or equal to 82%, less than or equal to 80%, less than or equal to 75%, less than or equal to 70%, less than or equal to 65%, less than or equal to 60%, less than or equal to 55%, less than or equal to 50%, less than or equal to 45%, less than or equal to 40%, less than or equal to 35%, less than or equal to 30%, less than or equal to 25%, less than or equal to 20%, less than or equal to 15%, less than or equal to 10%, less than or equal to 5%, or any range or value therein between.

[0087] In some embodiments, the copolymer has a degree of sulfonation of at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, or any range or value therein between.

[0088] In some embodiments, the copolymer has a degree of sulfonation of 5% to 80%, 5% to 75%, 5% to 70% 5% to 65%, 5% to 60%, 5% to 55%, 5% to 50%, 5% to 45%, 5% to 40%, 5% to 35%, 5% to 30%, 5% to 25%, 5% to 20%, 10% to 80%, 10% to 75%, 10% to 70%, 10% to 65%, 10% to 60%, 10% to 55%, 10% to 50%, 10% to 45%, 10% to 40%, 10% to 35%, 10% to 30%, 10% to 25%, 10% to 20%, 15% to 80%, 15% to 75%, 15% to 70%, 15% to 65%, 15% to 60%, 15% to 55%, 15% to 50%, 15% to 45%, 15% to 40%, 15% to 35%, 15% to 30%, 15% to 25%, 15% to 20%, 20% to 80%, 20% to 75%, 20% to 70%, 20% to 65%, 20% to 60%, 20% to 55%, 20% to 50%, 20% to 45%, 20% to 40%, 20% to 35%, 20% to 30%, 20% to 25%, 25% to 80%, 25% to 75%, 25% to 70%, 25% to 65%, 25% to 60%, 25% to 55%, 25% to 50%, 25% to 45%, 25% to 40%, 25% to 35%, 25% to 30%, 30%to 80%, 30% to 75%, 30% to 70%, 30% to 65%, 30% to 60%, 30% to 55%, 30% to 50%, 30% to 45%, 30% to 40%, 30% to 35%, 35% to 80%, 35% to 75%, 35% to 70%, 35% to 65%, 35% to 60%, 35% to 55%, 35% to 50%, 35% to 45%, 35% to 40%, 40% to 80%, 40% to 75%, 40% to 70%, 40% to 65%, 40% to 60%, 40% to 55%, 40% to 50%, 40% to 45%, or any range or value therein.

[0089] In some embodiments, the copolymer is a random polymer. In some embodiments, the copolymer is a block copolymer. In some embodiments, the copolymer has a structure according to Formula (IV) below.X OO or O"5"O(IV)

[0090] In some embodiments, n is at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, at least 75, at least 80, at least 85, at least 90, at least 95, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 450, at least 500, at least 600, at least 700, at least 800, at least 900, at least 1000, at least 2000, at least 3000, at least 4000, at least 5000, at least 10000, at least 15000, at least 20000, or greater.

[0091] In some embodiments, the hydrophobic monomer is present within the copolymer at a concentration, by fraction of all monomer units, of greater than or equal to about 10%, greater than or equal to about 15%, greater than or equal to about 20%, greater than or equal to about 25%, greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, greater than or equal to about 50%, greater than or equal to about 55%, greater than or equal to about 60%, greater than or equal to about 65%, greater than or equal to about 70%, greater than or equal to about 75%, greater than or equal to about 80%, greater than or equal to about 85%, greater than or equal to about 90%, or any range or value therein between.

[0092] In some embodiments, the hydrophobic monomer is present within the copolymer at a concentration, by fraction of all monomer units, of less than or equal to about 90%, lessthan or equal to about 85%, less than or equal to about 80%, less than or equal to about 75%, less than or equal to about 70%, less than or equal to about 65%, less than or equal to about 60%, less than or equal to about 55%, less than or equal to about 50%, less than or equal to about 45%, less than or equal to about 40%, less than or equal to about 35%, less than or equal to about 30%, less than or equal to about 25%, less than or equal to about 20%, less than or equal to about 15%, less than or equal to about 10%, or any range or value therein between.

[0093] In some embodiments, the hydrophobic monomer is present within the copolymer at a concentration, by fraction of all monomer units, of about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, or any range or value therein.

[0094] In some embodiments, the sulfonated monomer unit is present within the copolymer at a concentration, by fraction of all monomer units, of greater than or equal to about 5%, greater than or equal to about 10%, greater than or equal to about 15%, greater than or equal to about 20%, greater than or equal to about 25%, greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, greater than or equal to about 50%, or any range or value therein between.

[0095] In some embodiments, the sulfonated monomer unit is present within the copolymer at a concentration, by fraction of all monomer units, of less than or equal to about 50%, less than or equal to about 45%, less than or equal to about 40%, less than or equal to about 35%, less than or equal to about 30%, less than or equal to about 25%, less than or equal to about 20%, less than or equal to about 15%, less than or equal to about 10%, less than or equal to about 5%, or any range or value therein between.

[0096] In some embodiments, the sulfonated monomer is present within the copolymer at a concentration, by fraction of all monomer units, of about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, or any range or value therein between.

[0097] In some embodiments, the non-sulfonated monomer unit is present within the copolymer at a concentration, by fraction of all monomer units, of greater than or equal to about 5%, greater than or equal to about 10%, greater than or equal to about 15%, greaterthan or equal to about 20%, greater than or equal to about 25%, greater than or equal to about 30%, greater than or equal to about 35%, greater than or equal to about 40%, greater than or equal to about 45%, greater than or equal to about 50%, or any range or value therein between.

[0098] In some embodiments, the non-sulfonated monomer unit is present within the copolymer at a concentration, by fraction of all monomer units, of less than or equal to about 50%, less than or equal to about 45%, less than or equal to about 40%, less than or equal to about 35%, less than or equal to about 30%, less than or equal to about 25%, less than or equal to about 20%, less than or equal to about 15%, less than or equal to about 10%, less than or equal to about 5%, or any range or value therein between.

[0099] In some embodiments, the non-sulfonated monomer is present within the copolymer at a concentration, by fraction of all monomer units, of about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, or any range or value therein between.Molecular Weight

[0100] In some embodiments, the copolymer has a weight average molecular weight (Mw) of at least t least about 5,000 g / mol, at least about 6,000 g / mol, at least about 7,000 g / mol, at least about 8,000 g / mol, at least about 9,000 g / mol, at least about 10,000 g / mol, at least about 15,000 g / mol, at least about 20,000 g / mol, at least about 25,000 g / mol, at least about 30,000 g / mol, at least about 35,000 g / mol, at least about 40,000 g / mol, at least about 45,000 g / mol, at least about 50,000 g / mol, at least about 60,000 g / mol, at least about 70,000 g / mol, at least about 80,000 g / mol, at least about 90,000 g / mol, at least about 100,000 g / mol, at least about 150,000 g / mol, at least about 200,000 g / mol, at least about 250,000 g / mol, at least about 300,000 g / mol, at least about 350,000 g / mol, at least about 400,000 g / mol, at least about 450,000 g / mol, at least about 500,000 g / mol, at least about 550,000 g / mol, at least about 600,000 g / mol, at least about 650,000 g / mol, at least about 700,000 g / mol, at least about 750,000 g / mol, at least about 800,000 g / mol, at least about 850,000 g / mol, at least about 900,000 g / mol, at least about 950,000 g / mol, at least about 1,000,000 g / mol, or any range or value therein between.

[0101] In some embodiments, the copolymer has a weight average molecular weight (Mw) of no greater than about 1,000,000 g / mol, no greater than about 950,000 g / mol, nogreater than about 900,000 g / mol, no greater than about 850,000 g / mol, no greater than about 800,000 g / mol, no greater than about 750,000 g / mol, no greater than about 700,000 g / mol, no greater than about 650,000 g / mol, no greater than about 600,000 g / mol, no greater than about 550,000 g / mol, no greater than about 500,000 g / mol, no greater than about 450,000 g / mol, no greater than about 400,000 g / mol, no greater than about 350,000 g / mol, no greater than about 300,000 g / mol, no greater than about 250,000 g / mol, no greater than about 200,000 g / mol, no greater than about 150,000 g / mol, no greater than about 100,000 g / mol, no greater than about 90,000 g / mol, no greater than about 80,000 g / mol, no greater than about 70,000 g / mol, no greater than about 60,000 g / mol, no greater than about 50,000 g / mol, no greater than about 45,000 g / mol, no greater than about 40,000 g / mol, no greater than about 35,000 g / mol, no greater than about 30,000 g / mol, no greater than about 25,000 g / mol, no greater than about 20,000 g / mol, no greater than about 15,000 g / mol, no greater than about 10,000 g / mol, no greater than about 9,000 g / mol, no greater than about 8,000 g / mol, no greater than about 7,000 g / mol, no greater than about 6,000 g / mol, no greater than about 5,000 g / mol, or any range or value therein between.

[0102] In some embodiments, the copolymer has a weight average molecular weight (Mw) of about 5,000 g / mol to 1,000,000 g / mol, about 5,000 g / mol to about 500,000 g / mol, about 5,000 g / mol to about 100,000 g / mol, about 5,000 g / mol to about 50,000 g / mol, about 5,000 g / mol to about 25,000 g / mol, about 5,000 g / mol to about 10,000 g / mol, about 5,000 g / mol to about 9,000 g / mol, or any range or value therein between.Distance Between Sulfonic Groups

[0103] In some embodiments, the copolymer has an average distance between sulfonic groups, as determined by SAXS or WAXS, of less than or equal to 0.8 nm, less than or equal to 0.75 nm, less than or equal to 0.7 nm, less than or equal to 0.65 nm, less than or equal to 0.60 nm, less than or equal to 0.55 nm, less than or equal to 0.50 nm, less than or equal to 0.48 nm, less than or equal to 0.45 nm, less than or equal to 0.42 nm, less than or equal to 0.40 nm, less than or equal to 0.38 nm, less than or equal to 0.35 nm, or any range or value therein between.Proton Conductivity

[0104] In some embodiments, the copolymer has a proton conductivity of greater than or equal to 0.1 S • cm’1, greater than or equal to 0.15 S • cm’1, greater than or equal to 0.2 S- cm'1, greater than or equal to 0.25 S cm’1, greater than or equal to 0.30 S cm’1, greater than or equal to 0.35 S cm'1, greater than or equal to 0.40 S cm'1, greater than or equal to 0.45 S cm'1, greater than or equal to 0.50 S cm'1, or any range or value therein between. In some embodiments, the proton conductivity is measured at 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C.Effective Proton Mobility

[0105] In some embodiments, the copolymer has an effective proton mobility of greater than or equal to 0.01 x 10'5cm2s'*- V'1, greater than or equal to 0.015 x 10'5cm2s'J- V'1, greater than or equal to 0.020 x 10'5cm2- s'1- V'1, greater than or equal to 0.025 x 10'5cm2- s'1- V'1, greater than or equal to 0.030 x 10'5cm2- s'1- V'1, greater than or equal to 0.035 x 10'5cm2?1-?1, greater than or equal to 0.040 x 1O'5cm2^1?'1, greater than or equal to 0.045 x 10'5cm2^1-"?'1, greater than or equal to 0.050 x 10'5ernes'1-"?'1, greater than or equal to 0.055 x 10'5ernes'1- V'1, greater than or equal to 0.060 x 10'5cm2^1?'1, greater than or equal to 0.065 x 10'5cm2^1-"?'1, greater than or equal to 0.070 x 10'5cm2^1-"?'1, greater than or equal to 0.075 x 10'5cm2- s'1- V'1, greater than or equal to 0.080 x 10'5cm2s'J- V'1, greater than or equal to 0.085 x 10'5cm2- s'1- V'1, greater than or equal to 0.090 x 10'5cm2- s'1- V'1, greater than or equal to 0.095 x 10'5cm2- s'1- V'1, greater than or equal to 0.10 x 10'5cm2- s'1- V'1, or any range or value therein between. In some embodiments, the effective proton mobility is measured at 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C.Methanol Permeability

[0106] In some embodiments, the copolymer has a methanol permeability Pueoii) of less than or equal to 1.5 * 10'6ernes’1, less than or equal to 1.4 * 10'6ernes'1, less than or equal to 1.3 x 10'6cm2- s'1, less than or equal to 1.2 x 10'6cm2- s'1, less than or equal to 1.1 x 10'6cm2- s'1, less than or equal to 1.0 x 10'6cm2- s'1, less than or equal to 0.9 x 10'6cm2- s'1, less than or equal to 0.8 x 10'6cm2s'1, less than or equal to 0.7 x 10'6cm2s'1, less than or equal to 0.6 x 10'6cm2s'*, less than or equal to 0.5 x 10'6cm2s'*, less than or equal to 0.45 x 10'6ernes'1, less than or equal to 0.40 x 10'6ernes'1, less than or equal to 0.35 x 10'6cm2s'*, less than or equal to 0.30 x 1O'6ernes'1, less than or equal to 0.25 x 1O'6cm2s' less than or equal to 0.20 x 10'6cm2- s'1, less than or equal to 0.15 x 10'6cm2s'1, less than or equal to 0.10 x 10'6cm2- s'1, less than or equal to 0.05 x 10'6cm2- s'1, or any range or value therein between. In some embodiments, the effective methanol mobility is measured at 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, or 65°C.Normalized Selectivity

[0107] In some embodiments, the copolymer has a normalized selectivity (determined as disclosed in Example 1), relative to NAFION® 117, of greater than 1, greater than or equal to about 1.1, greater than or equal to about 1.2, greater than or equal to about 1.3, greater than or equal to about 1.4, greater than or equal to about 1.5, greater than or equal to about 1.6, greater than or equal to about 1.7, greater than or equal to about 1.8, greater than or equal to about 1.9, greater than or equal to about 2.0, greater than or equal to about 2.5, greater than or equal to about 3.0, greater than or equal to about 3.5, greater than or equal to about 4.0, greater than or equal to about 4.5, greater than or equal to about 5.0, greater than or equal to about 5.5, greater than or equal to about 6.0, greater than or equal to about 6.5, greater than or equal to about 7.0, greater than or equal to about 7.5, greater than or equal to about 8.0, greater than or equal to about 8.5, greater than or equal to about 9.0, greater than or equal to about 9.5, greater than or equal to about 10, greater than or equal to about 15, greater than or equal to about 20, or any range or value therein between.Methods of Making Copolymers

[0108] In another aspect, which may be combined with any other aspect or embodiment, the present disclosure relates to methods of making copolymers comprising: (i) a sulfonated monomer comprising a sulfonated (arylene ether sulfone), a sulfonated(arylene ether ketone), or a combination thereof, and (ii) a hydrophobic monomer. In some embodiments, the present disclosure relates to methods of making copolymers comprising: (i) a sulfonated monomer comprising a sulfonated (arylene ether sulfone), a sulfonated (arylene ether ketone), or a combination thereof; (ii) a hydrophobic monomer; and (iii) a non-sulfonated monomer comprising a non-sulfonated (arylene ether sulfone), a nonsulfonated (arylene ether ketone), or a combination thereof.

[0109] In some embodiments, the methods of making copolymers comprise polymerizing: (i) a sulfonated monomer comprising a sulfonated (arylene ether sulfone), a sulfonated (arylene ether ketone), or a combination thereof, with (ii) a hydrophobic monomer, to obtain the copolymer. In some embodiments, the methods of making copolymers comprise polymerizing the following monomers with one another: (i) a sulfonated monomer comprising a sulfonated (arylene ether sulfone), a sulfonated (arylene ether ketone), or a combination thereof; (ii) a hydrophobic monomer; and (iii) a non- sulfonated monomer comprising a non-sulfonated (arylene ether sulfone), a non-sulfonated (arylene ether ketone), or a combination thereof, to obtain the copolymer.

[0110] In some embodiments, the sulfonated monomer is pre-sulfonated (z.e., directly sulfonated), such that it has sulfonic groups before the polymerization reaction. In some embodiments, the sulfonated monomer is post-sulfonated (z.e., sulfonated after polymerization).Membrane Electrode Assemblies and Fuel Cells

[0111] In another embodiment, which may be combined with any other aspect or embodiment, the present disclosure relates to a membrane electrode assembly (MEA), comprising: an anode; a cathode; and a PEM disposed between the anode and the cathode, wherein the PEM is the PEM according to any of the embodiments disclosed above.

[0112] In some embodiments, the PEM has a thickness of greater than or equal to about 10 pm, greater than or equal to about 20 pm, greater than or equal to about 30 pm, greater than or equal to about 40 pm, greater than or equal to about 50 pm, greater than or equal to about 60 pm, greater than or equal to about 70 pm, greater than or equal to about 80 pm, greater than or equal to about 90 pm, greater than or equal to about 100 pm, greater than or equal to about 150 pm, greater than or equal to about 200 pm, greater than or equal to about 250 pm, greater than or equal to about 300 pm, greater than or equal to about 350qm, greater than or equal to about 400 qm, greater than or equal to about 450 qm, greater than or equal to about 500 qm, greater than or equal to about 550 qm, greater than or equal to about 600 qm, greater than or equal to about 650 qm, greater than or equal to about 700 qm, greater than or equal to about 750 qm, greater than or equal to about 800 qm, greater than or equal to about 850 qm, greater than or equal to about 900 qm, greater than or equal to about 950 qm, greater than or equal to about 1 mm, or any range or value therein between.

[0113] In some embodiments, the PEM has a thickness of less than or equal to about 1 mm, less than or equal to about 950 qm, less than or equal to about 900 qm, less than or equal to about 850 qm, less than or equal to about 800 qm, less than or equal to about 750 qm, less than or equal to about 700 qm, less than or equal to about 650 qm, less than or equal to about 600 qm, less than or equal to about 550 qm, less than or equal to about 500 qm, less than or equal to about 450 qm, less than or equal to about 400 qm, less than or equal to about 350 qm, less than or equal to about 300 qm, less than or equal to about 250 qm, less than or equal to about 200 qm, less than or equal to about 150 qm, less than or equal to about 100 qm, less than or equal to about 90 qm, less than or equal to about 80 qm, less than or equal to about 70 qm, less than or equal to about 60 qm, less than or equal to about 50 qm, less than or equal to about 40 qm, less than or equal to about 30 qm, less than or equal to about 20 qm, or any range or value therein between.

[0114] In another aspect, which may be combined with any other aspect or embodiment, the present disclosure relates to a fuel cell comprising an electrochemical cell comprising a membrane electrode assembly, the membrane electrode assembly comprising: an anode; a cathode; and a PEM disposed between the anode and the cathode, wherein the PEM is the PEM according to any of the embodiments disclosed above. In some embodiments, the fuel cell is a direct methanol fuel cell (DMFC).

[0115] Reference will now be made in detail to some specific examples demonstrating the technology of the disclosure. While various experimental examples are described herein, it will be understood that it is not intended to limit the present technology to the described embodiments.EXAMPLESExample 1. Synthesis and Characterization of SPAES and SPAEK

[0116] To test the viability of SPAES and SPAEK as polymer materials for PEMs, two sulfonated poly(arylene) series polymers based on sulfone and ketone units (SPAES and SPAEK, respectively) were synthesized and characterized as follows. The polymers were created to achieve a random structure, starting with a pre-sulfonated unit.Materials

[0117] 4,4’-Dichlorobiphenyl sulfone (DCDPS, 98.0+%) and 2,2-bis(4- hydroxyphenyl) propane (BPA, 99.0+%) were obtained from TCL America and dried at 60 °C prior to use. N,N-dimethylacetamide (DMAc, 99%), 2-propanol (IP A, 99.5%), sulfuric acid (20% fuming, 18-24% free SO3), and 4,4’-dichlorobenzophenone (DCBP, 99%) were purchased from Alfa Aesar and were used without further purification. Toluene (ACS grade), methanol (99.8%, extra dry), and sulfuric acid (ACS grade) were obtained from Fisher Scientific. Potassium carbonate (K2CO3, 98%) was obtained from Acros Organics.Synthesis of Sulfonated Unit

[0118] To a 250 mL three-necked flask with a nitrogen inlet / outlet, 28.7 g of DCDPS or DCBP was added and dissolved in 60 mL of fuming sulfuric acid. The solution was heated to 110°C for 6 hours. The reaction mixture was cooled to room temperature, and 400 mL of cold water was added. Then, 180 g of NaCl was added, and the disodium salt of SDCDPS precipitated as a white powder. The precipitate was recovered by filtration, dissolved in 400 mL of cold deionized water, and treated with a 2 M solution of NaOH to a pH of 6-7.

[0119] An excess amount of NaCl (60 g) was added again to salt out the sodium form of the monomer. The final product (white needle crystals) was filtered and recrystallized from methanol and deionized water (9: 1 (v / v)).Synthesis of Sulfone / Ketone Based Random Polymers

[0120] Scheme 1 shows the procedure followed to prepare the 25% sulfonated random poly(arylene ether sulfone) (SPAES A 25) or 25% sulfonated random poly(arylene ether ketone) (SPAEK A 25). All monomers were dried before use. All syntheses were performed in triplicate. Temperatures were controlled using a sensor-monitored heating mantle.

[0121] First, 5.5 mmol of BP A, 2.25 mmol of DCDPS or DCBP, 2.5 mmol of SDCDPS or SDCBP (rapidly weighed) were added to a 250 mL three-necked flask with a stirrer, a nitrogen inlet, and a Dean-Stark trap. Potassium carbonate (11.8 mmol) and sufficient DMAc were added to afford a 20% (w / v) solid concentration. Toluene (DMAc / toluene, 2: 1 (v / v)) was used as an azeotroping agent. The reaction mixture was refluxed at 150 °C for 4 h to dehydrate the system. The temperature was raised slowly to 165 °C for controlled toluene removal. The reaction was allowed to proceed for 24 h, over which the reaction solution became very viscous. The solution was then cooled to room temperature and diluted with enough DMAc to allow filtering. After filtration, most of the salts were removed, and the copolymer was isolated by coagulation in 2-propanol. The precipitated copolymer was washed several times with deionized water to remove the residual salts. Finally, the precipitated copolymer was dried at 60 °C for 48 h.Scheme 1. Synthesis of SPAEK A25 and SPAES A25 Random PolymersX; C"Q or Q-S--0CharacterizationFourier Transform Infrared (FTIR) Spectroscopy

[0122] To perform qualitative screening of intermediate steps and the final copolymer, FTIR spectroscopy was performed. Spectra were obtained using a Bruker ALPHA Platinum FT-IR spectrometer with a diamond attenuated total reflection (ATR)holder and a wavenumber range of 500-4000 cm’1, using 100 scans with a 4 cm’1resolution.Thermogravimetric Analysis (TGA)

[0123] TGA was performed using TA Instruments TGA Q50 thermogravimetric analyzer to assess the thermal stability of copolymer membranes. Briefly, samples weighing 20-30 mg were heated from 25 °C to 800 °C under a nitrogen atmosphere using a heating rate of 10 °C min1.Oxidative Stability

[0124] To evaluate the oxidative stability of the composite membranes, Fenton's test, which consists of an accelerated oxidative degradation method, was performed. From previously dried membranes, duplicates were immersed in 10 mL Fenton's reagent (4 ppm Fe(SO4)2-7H2O in 3 wt.% H2O2 aqueous solution) at 60 °C for 72 h. Every 24 h, the Fenton’s solution was replaced, and the residual weight (RW) was measured after removing the excess solution from the sample when the period ended. The RW was calculated as shown below:RIV(wt %) = 2=="’' initialIon Exchange Capacity

[0125] IEC is obtained by immersing pre-dried membranes into 1 M NaCl solution for 24 h. After this period, the membrane is removed from the solution, and the solution is titrated with 0.01 M NaOH solution until neutral pH is obtained. The IEC is determined using the ion mole ratio per dry membrane weight, as shown below. Samples were analyzed in triplicates.Water Uptake, Swelling Ratio, and Water Content

[0126] The water absorption capabilities for the SPAES and SPAEK polymers were determined by gravimetric methods. The water uptake is the weight difference between dry and wet membranes. First, dry membranes are weighed and placed into deionized water for 24 h at room temperature. Then, the wet membrane is blotted dry and weighed again. Water uptake is determined as shown below:100

[0127] Water content (X) describes the number of water molecules surrounding an ionic domain and is calculated as shown below:10 x Water Uptake18 x IECAtomic Force Microscopy (AFM)

[0128] Phase images of the membranes were obtained using an Agilent AFM 550 in AC imaging mode at room temperature. Silicon scanning probe microscopy cantilevers were used for the noncontact test. Measurements were performed for dry membrane samples and 48-hour hydrated samples. All images were obtained with a resolution of 256 and a scanning speed of 2.01 lines / second.

[0129] Small-angle x-ray scattering (SAXS) was used to analyze morphological differences between the different membranes and to determine the interatomic distances.SAXS experiments were performed on dried samples under vacuum at 25°C, with an x-ray exposure time of 1 min. SAXS profiles were obtained normal to the plane of the membranes using a SAXSpace (Anton Paar) system with CuKa as the radiation source, operated at 50 mA and 40 kV. The scattering patterns were collected using image plates as detectors and a PerkinElmer CYCLONE® Plus image plate reader. Then, the data were corrected and converted to one-dimensional intensity using SAXSTREAT® software and SAXSQUANT® software, respectively.

[0130] The interstitial distance between atoms was calculated using Bragg's law (shown below), wherein d is the distance between atoms and q is the scattering vector.2TT d = — qProton Conductivity, Effective Proton Mobility, and Methanol Permeability

[0131] Proton conductivity (c) was obtained using a Fuel Test System, 850e multirange, equipped with an 885 Fuel Cell Potentiostat (Scribner Associates Inc), using apreviously reported procedure. See M. Perez -Perez & D. Suleiman, J. AppL Pofym. Sci. 133S (2016); Aviles-Barreto, & D. Suleiman, 129 J. Appl. Polym. Sci. 2294 (2013).

[0132] Proton conductivity (o) is calculated as shown in the Equation below, wherein L (cm) is the membrane thickness and A (cm2) is the membrane area. Real impedance (Q) is obtained from the x-intercept of the Nyquist plot.

[0133] Once proton conductivity is calculated, the effective proton mobility ( / / <) is calculated using the [ionic domain], Faraday's constant (F), and cr.

[0134] Methanol permeability (PMBOH) is measured at room temperature using a side-by-side diffusion cell. Previously hydrated membranes are placed between the two compartments of the cell. The donor compartment is filled with a 2 M methanol solution, while the acceptor compartment is filled with DI water. The concentration of methanol is obtained using FTIR by monitoring the C-0 stretch at 1014 cm’1, and the permeability coefficient is obtained from the slopeCb^-)Vb LVS. t. Diffusion in-plane sheet geometryapproximation is used. Here, CA (M) and CB (M) are methanol concentration at donor and acceptor compartments, respectively, L is the membrane thickness (cm), A is the membrane cross-sectional area (cm2), D is methanol diffusion coefficient (cm2 / s), and P (cm2 / s) is the permeability.

[0135] Once the proton conductivity and methanol permeability values are determined, the selectivity of the membranes is calculated by dividing the proton conductivity by the methanol permeability ratio. The membrane selectivity is normalized using the reported values for the state-of-the-art commercial NAFION® 117 at 50 °C, as shown below.Example 2. Fourier Transform Infrared Spectroscopy

[0136] FTIR spectra of SPAES A 25, SPAEK A 25, SDCDPS, and SDCBP are shown in FIG. 1. Starting from the sulfonated monomer units (SDCDPS and SDCBP), the signals at 1021 cm'1and 1090 cm'1were assigned to the SChNa group's symmetric and asymmetric stretching, respectively. The stretching signal at 1168 cm'1also confirms the units' sulfonation. The 1010 cm'1bands observed for the SPAES A 25 and SPAEK A 25 polymers confirm the creation of the arylene-oxygen-arylene bonds, which indicates that the sulfonated and non-sulfonated units are incorporated into the polymers. From this analysis, the isopropyl signal corresponding to the BPA unit is present at 1393 cm'1. Ketone and sulfone characteristic bands are identified at -1650 cm'1for the C=O stretch and at 1308 cm'1and 1151 cm'1, corresponding to the symmetric and asymmetric stretch of O=S=O groups. The data confirm the presence of the sulfonated and non-sulfonated monomer units in the polymers.Example 3. Thermogravimetric Analysis

[0137] Thermal stability of the synthesized polymers was studied by TGA.Referring to FIG. 2, the data showed five main transitions for the sulfone-based polymer and four for the ketone-based polymer. (See Table 1.) Transitions below 300°C for these polymers are related to the decomposition of the sulfonic groups. The transitions near 400 °C can be associated with the degradation of aliphatic groups from BPA. The degradation of sulfonic groups on SPAES A 25 occurs in three steps, compared to only two SPAEK A 25. The increase in number of degradation steps for SPAES A 25 suggests increased ionic domain interactions that prevent these groups from undergoing a single-step degradation, as observed in sulfonated SIBS, or a two-step degradation, as observed in the ketone-based polymer (SPAEK A 25). Transitions at 498 °C and 484 °C correspond to thermal degradation of the polymer backbone for SPAES A 25 and SPAEK A 25, respectively. In the last step, a 14°C difference is also observed for the backbone degradation of the sulfone- based polymer versus the ketone-based polymer, suggesting that sulfones have a stabilizing effect on the polymeric main chain. At 500°C, both polymers retain over 50% of theirinitial weight, which makes them good candidates for PEMFC operated at elevated temperatures.Table 1. Thermal transition temperatures for SPAES A 25 and SPAEK A 25 polymers.Example 4. Oxidative Stability

[0138] The Fenton’s test was used to determine oxidative stability for the random copolymers. Referring to Table 2, it is apparent that the action of the oxidative species destroyed the sulfone-based polymer, while the ketone-based polymer retained approximately 89% of its initial weight. Structurally, the more crystalline behavior of the poly(aryl) ether ketone appears to play a protective role for the polymer as a whole. From water capabilities analysis, the difference in water uptake between polymers may explain the remaining weight results. The sulfone-based polymer water uptake was three times higher than that observed for the ketone polymer, implying that oxidative species could have had easier access to the polymer matrix, facilitating the oxidative attack of carbon linkages. Additionally, the ion exchange capacity difference between the polymers is related to the oxidative attack effectiveness due to the aqueous Fenton's reagent's swelling of ionic groups.Table 2. Remaining weight (%) after 72 hours for random SPAEK A 25 and SPAES A 25 polymers at 60°C.Example 5. Ion Exchange Capacity (IEC), Water Uptake, and Water Content

[0139] IEC, water uptake, and water content tests were performed for the two random polymers. The results are shown in FIG. 3A, FIG. 3B, and FIG. 3C. Referring to FIG. 3A, a clear difference in the water uptake behavior is observed between the two polymers. The sulfone-based polymer (SPAES A 25) exhibits three times the ability to absorb water as compared to the ketone-based polymer (SPAEK 25). From a chemical structural view, sulfone-based polymers are more suitable for hydrophilic environments because they form more hydrogen bonds with water than ketones. Oroujzadeh and Mehdipour-Ataei reported that the presence of sulfone groups on a polymeric backbone lowers the general density of the polymer, allowing more solvent interactions in a limited space. (See M. Oroujzadeh, M. & S. Mehdipour-Ataei, 33 Polym. Adv. TechnoL 2896 (2022).

[0140] FIG. 3B presents the ion exchange capacity (IEC) for the SPAES A 25 and SPAEK A 25. SPAES A 25 exhibits approximately double the IEC observed for SPAEK A 25, but both are low. Two explanations are considered. First, the ionic domains possibly are inaccessible to counter-ion substitution in the IEC experiment. Second, the pre-sulfonated units possibly were not fully sulfonated. The presence of ionic domains that cannot exchange protons influences the test outcome, thereby causing underestimation in the degree of sulfonation. For example, Yang and Manthiram prepared a series of 44 to 58% sulfonated poly(ether ketones). For their results, IEC values ranged from 1.36 to 1.74 meq. g’1, but the maximum water uptake was 5.3%. Interestingly the obtained conductivity was lower than Nafion® at 80 °C, which supports the rationale expressed above. (See B. Yang & A. Manthiram, 6 Electrochem. Solid-State Lett. A229 (2003).)

[0141] The water content per ionic domain were calculated based on the water uptake and ion exchange capacity of the membranes (FIG. 3C). Consistent with the water uptake results, the sulfone-based polymer obtained a higher water content than the ketone- based polymer. The L values represent a complex number often used to predict high proton conductivities. As a rule, proton conductivity increases with L values, as the water is bound to ionic domains and facilitates proton conduction. However, there is a limit where elevated water content on the membrane becomes bulk water incapable of permitting proton transport, thus dissolving the available acid sites for conduction.Example 6. Atomic Force Microscopy

[0142] AFM can be used to analyze phase segregation on a given material.Referring now to FIG. 4, there appear to be two distinct phase segregation patterns in the random sulfone-and ketone-based polymers. First, a clear distinction between hydrophilic (dark regions) and hydrophobic (bright regions) was observed for a 25 pm * 25 pm scanning area ((A) and (C)). These results agree with the water uptake and oxidative stability results because the ketone-based polymer has an intercalated-like shape at this scale, making the polymer chains less accessible to water.

[0143] For the small scan area (100 nm x 100 nm; (B) and (D)), the morphology is more uniform over this scale. This result suggests a poorly-segregated microphase.However, a slight difference is observed between the SPAEK (B) and SPAES (D) polymers. For SPAEK, the hydrophilic domains appear to be concentrated on the upper part of the image, separated by hydrophobic continuous sections, suggesting a generally intercalated phase, even at this smaller length scale. On the other hand, for SPAES (D), the hydrophilic domains are more evenly distributed across the scan area, even when no interconnection can be observed. These findings, combined with the water absorption tests, explain why sulfone-based polymers present a more favorable platform for higher proton conductivity than ketone-based polymers.Example 7. Small Angle X-Ray Scattering and Wide Angle X-Ray Scattering

[0144] Referring now to FIG. 5 (top), SAXS analysis found two characteristic peaks for both random polymers. First, two distinct peaks are observed in the 0.1-0.2 nm'1region, indicating inter-atomic distances of 42.34 nm and 50.72 nm for the ketone and sulfone polymers, respectively. Additionally, two peaks appear in the 8-16 nm'1WAXS region (see FIG. 5 (bottom)), providing nearly the same Bragg's distances as observed in the SAXS experiments (0.4841 nm and 0.49 nm for ketone and sulfone polymers, respectively). These results are summarized in Table 3.Table 3. Scattering Vector (q) and Braggs Distance (d) for Random Sulfone and Ketone 25% Sulfonated Polymers

[0145] From a chemical structure perspective, the first peaks (SAXS) are attributed to the characteristic ionomers on the polymer, biphenyl ketones or sulfones, separated by BPA units. The elevated poly(ketone) crystallinity has been widely reported over poly(sulfone) polymers. Despite this fact, the synthesis route chosen for these experiments places a BPA unit between dichloro ketone / sulfone units and sulfonated units. This BPA intercalation is why the characteristic ionomer mean distance is comparable between the two polymers, even though the two polymers have important structural differences.

[0146] From the second Bragg's distance (from WAXS), it is possible that this mean distance represents the SO3H group separation, indicative of the sulfonated units distributed across the polymer backbone. Along these lines, the peak intensities for SPAEK A 25 and SPAES A 25 are similar, indicative of similarities in sulfonation between the polymers. However, with respect to phase segregation, the SO3H mean separation being shorter in the sulfone-based polymer could indicate a less phase-segregated membrane.

[0147] Another important consideration is the packing of the polymeric structure. Due to the rigid nature of the poly(arylene ether) polymers, they are expected to have smaller ionic clusters, like those found in SAXS analysis (Table 3). The cluster size reported for SPEEK is about 1 nm and 5 nm for NAFION®. When comparing the cluster size of the instant SPAES and SPAEK polymers with SPEEK and NAFION®, it is possible that the cluster sizes of < 0.50 nm for the SPAES AND SPAEK polymers may play an important role in distributing water across the membrane. Further, even when the structure of the ketone and sulfone-based polymers is similar, the presence of the sulfone alters the packing trend of the backbone. Thus, the combination of interactions between ionic groups promotes a higher water content across the backbone for the sulfone versus the ketone, which creates a more suitable environment for proton conduction.Example 8. Proton Conductivity, Effective Proton Mobility, and Methanol Permeability

[0148] The proton transport properties and methanol permeabilities of the SPAES AND SPAEK polymers were studied at 50°C and 80°C and are presented in FIGs. 6A-6D. Referring to FIG. 6A, as expected, the proton conductivity was higher for the sulfonebased-polymer at 50°C and 80°C. The improved phase segregation for the SPAES A 25 polymer favored the proton conductivity over the SPAEK polymer and NAFION® 117. It has been previously reported that NAFION® possesses a lamellar structure separating the hydrophobic domains, allowing an improved interconnection of its hydrophilic groups. From the AFM results (Example 6), the SPAES polymer appears to have a better-organized phase behavior, facilitating the presence of water near the ionic conducting groups and, therefore, higher proton conduction.

[0149] From the water absorption tests (Example 5), the obtained X values showed differences between the SPAES and SPAEK polymers. However, despite the higher water content observed for the sulfone polymer, both materials follow the vehicular proton transport mechanism. (See Z. Zuo, et al, 4 Polymers 1627 (2012).

[0150] This result has important implications for effective proton mobility, which measures the tortuosity of the ionic channels. The effective proton mobilities are shown in FIG. 6C. SPAES A 25 achieved a higher effective proton mobility (0.065 x 10'5cm2s'1V'1at 80 °C) than SPAEK A 25. Having similar distances between sulfonic groups (see Table 4), the intercalated morphology (see FIG. 4) suggests a greater tortuosity for the protons to travel through the ketone polymeric matrix, when compared to NAFION® (5 x 10'4and 8 x 10'4cm2s'1V'1at 50°C and 80°C, respectively). This comparison supports the morphological impedance both polymeric structures present to the proton mobilities, particularly in the case of the ketone-based polymer.

[0151] Referring to FIG. 6B, both polymers achieved methanol permeability in the range of 10'6cm2s'1. However, the ketone-based polymer showed the lowest permeability — less than 0.25 x 10'6cm2s'1. The results obtained for SPAEK A 25 comport with reported values for SPEEK, which are lower than those for NAFION®. (See S. Xue G. Yin, 42 Eur. Polym. J. 776 (2006). As a possible explanation for this behavior, perfluorinated polymers have a highly hydrophobic backbone and an incredibly large hydrophilic sulfonic group composition in their microstructure. Sulfonic groups thus aggregate to form ion clusters in the presence of water, creating well-connected water channels. The SPAEK A 25 membrane's main chain is less hydrophobic, and the sulfonic acid group is less acidic than in the NAFION® membrane. Thus, there is less nanoseparation and a bigger hydrophobic-hydrophilic interface corresponding to highly dispersed sulfonic groups through the backbone of SPAEK A 25. Accordingly, compared toNAFION® membranes, the water-filled channels of SPAEK A 25 membrane may be more branched and present more dead-end pockets.

[0152] The membranes selectivity is presented in FIG. 6D. The best selectivity was obtained for the SPAEK A 25, achieving values near 5.8. Temperature does not appear to affect the selectivity. For the SPAES A 25 polymer, the temperature seems affect selectivity, as SPAES A 25 achieves its highest selectivity at 80°C. Both studied polymers achieve a selectivity superior to that observed for NAFION® 117. However, considering the thermal stability, proton conductivity, and comparable methanol permeability with NAFION®, SPAEK A 25 could be a viable candidate for DMFC, with higher oxidative stability.

[0153] The selectivity of both the sulfone- and ketone-based polymers exceeds reported values for NAFION®, and both could be viable candidates for DMFCs with specific modifications for proton conduction (SPAEK A 25) and oxidative stability (SPAES A 25).

[0154] The present technology is not to be limited in terms of the particular aspects described in this application, which are intended as single illustrations of individual aspects of the present technology. Many modifications and variations of this present technology can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatuses within the scope of the present technology, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the present technology. It is to be understood that this present technology is not limited to particular methods, reagents, compounds compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0155] The methods illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising”, “including,” containing”, etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intentionin the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof. It is recognized that various modifications are possible within the scope of the disclosure claimed. Thus, it should be understood that although the present disclosure has been specifically disclosed by preferred embodiments and optional features, modification and variation of the disclosure embodied therein herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this disclosure.

[0156] The disclosure has been described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the methods. This includes the generic description of the methods with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein. The present technology is not to be limited in terms of the particular embodiments described in this application, which are intended as single illustrations of individual aspects of the present technology. Many modifications and variations of this present technology can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatuses within the scope of the present technology, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the present technology. It is to be understood that this present technology is not limited to particular methods, reagents, compounds compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0157] One skilled in the art readily appreciates that the present disclosure is well adapted to carry out the objects and obtain the ends and advantages mentioned, as well as those inherent therein. Modifications therein and other uses will occur to those skilled in the art. These modifications are encompassed within the spirit of the disclosure and are defined by the scope of the claims, which set forth non-limiting embodiments of the disclosure.

[0158] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0159] All references, articles, publications, patents, patent publications, and patent applications cited herein are incorporated by reference in their entireties for all purposes.

[0160] However, mention of any reference, article, publication, patent, patent publication, and patent application cited herein is not, and should not be taken as, an acknowledgment or any form of suggestion that they constitute valid prior art or form part of the common general knowledge in any country in the world.

[0161] The present technology may include, but is not limited to, the features and combinations of features recited in the following lettered paragraphs, it being understood that the following paragraphs should not be interpreted as limiting the scope of the claims as appended hereto or mandating that all such features must necessarily be included in such claims:A. A proton exchange membrane (PEM), comprising: a copolymer comprising:(i) a sulfonated monomer comprising a sulfonated (arylene ether sulfone), a sulfonated (arylene ether ketone), or a combination thereof; and(ii) a hydrophobic monomer, wherein the copolymer has a degree of sulfonation of about 10% to about 50%.B. The PEM of Paragraph A, wherein the copolymer is a random copolymer.C. The PEM of Paragraph A or Paragraph B, wherein the sulfonated monomer is a monomer derived from a sulfonated poly(arylene ether sulfone).D. The PEM of Paragraph C, wherein the sulfonated monomer comprises a sulfonated biphenyl sulfone.E. The PEM of Paragraph A or Paragraph B, wherein the sulfonated monomer is monomer derived from a sulfonated poly(arylene ether ketone).F. The PEM of Paragraph E, wherein the sulfonated monomer comprises a monomer derived from a sulfonated benzophenone.G. The PEM of any one of Paragraphs A-F, wherein the sulfonated monomer is a monomer derived from 4,4’-dichlorodiphenylsulfone, a monomer derived from 4,4’- dichlorobenzophenone, or a combination thereof.H. The PEM of Paragraph G, wherein the hydrophobic monomer comprises a monomer unit derived from 2,2-bis(4-hydroxyphenyl) propane (BP A), a monomer unit derived from 4,4’-dihydroxyphenyl (BP), or a combination thereof.I. The PEM of Paragraph H, wherein the hydrophobic monomer comprises a monomer unit derived from BPA.J. The PEM of any one of Paragraphs A-I, wherein the copolymer further comprises (iii) a non-sulfonated monomer comprising a non-sulfonated arylene ether ketone, a nonsulfonated arylene ether sulfone, or a combination thereof.K. The PEM of Paragraph J, wherein the non-sulfonated arylene ether ketone is a benzophenone and the non-sulfonated arylene ether sulfone is a diphenyl sulfone.L. The PEM of any one of Paragraphs A-K, wherein the degree of sulfonation is about 20% to about 30%.M. The PEM of any one of Paragraphs A-L, wherein the average distance between sulfonic groups is less than or equal to 0.5 nm.N. The PEM of any one of Paragraphs A-M, wherein the PEM has a proton conductivity at50°C of 0.10 S cm'1or greater.O. The PEM of any one of Paragraphs A-N, wherein the PEM has a proton conductivity at80°C of 0.15 S cm'1or greater.P. The PEM of Paragraph O, wherein the proton conductivity at 80°C is 0.20 S cm'1or greater.Q. The PEM of any one of Paragraphs A-P, wherein the PEM has an effective proton mobility at 80°C of greater than 0.050 x 10'5cm2s'1V'1.R. The PEM of any one of Paragraphs A-Q, wherein the PEM has a methanol permeability of less than or equal to 1.5 x 10'6cm2s'1.S. A membrane electrode assembly (MEA), comprising: an anode; a cathode; and a PEM disposed between the anode and the cathode, wherein the PEM is the PEM of any one of Paragraphs A-R.T. A fuel cell comprising: an electrochemical cell comprising the membrane electrode assembly of Paragraph S.U. The fuel cell of Paragraph T, wherein the fuel cell is a direct methanol fuel cell.

[0162] Other embodiments are set forth in the following claims, along with the full scope of equivalents to which such claims are entitled.

Claims

WHAT IS CLAIMED IS:

1. A proton exchange membrane (PEM), comprising: a copolymer comprising:(i) a sulfonated monomer comprising a sulfonated (arylene ether sulfone), a sulfonated (arylene ether ketone), or a combination thereof; and(ii) a hydrophobic monomer, wherein the copolymer has a degree of sulfonation of about 10% to about 50%.

2. The PEM of claim 1, wherein the copolymer is a random copolymer.

3. The PEM of claim 1, wherein the sulfonated monomer is a monomer derived from a sulfonated poly(arylene ether sulfone).

4. The PEM of claim 3, wherein the sulfonated monomer comprises a sulfonated biphenyl sulfone.

5. The PEM of claim 1, wherein the sulfonated monomer is monomer derived from a sulfonated poly(arylene ether ketone).

6. The PEM of claim 5, wherein the sulfonated monomer comprises a monomer derived from a sulfonated benzophenone.

7. The PEM of claim 1, wherein the sulfonated monomer is a monomer derived from 4,4’- di chlorodiphenylsulfone, a monomer derived from 4,4’ -dichlorobenzophenone, or a combination thereof.

8. The PEM of claim 7, wherein the hydrophobic monomer comprises a monomer unit derived from 2,2-bis(4-hydroxyphenyl) propane (BP A), a monomer unit derived from 4,4’-dihydroxyphenyl (BP), or a combination thereof.

9. The PEM of claim 8, wherein the hydrophobic monomer comprises a monomer unit derived from BPA.

10. The PEM of claim 1, wherein the copolymer further comprises (iii) a non-sulfonated monomer comprising a non-sulfonated arylene ether ketone, a non-sulfonated arylene ether sulfone, or a combination thereof.

11. The PEM of claim 10, wherein the non-sulfonated arylene ether ketone is a benzophenone and the non-sulfonated arylene ether sulfone is a diphenyl sulfone.

12. The PEM of claim 1, wherein the degree of sulfonation is about 20% to about 30%.

13. The PEM of claim 1, wherein an average distance between sulfonic groups is less than or equal to 0.5 nm.

14. The PEM of claim 1, wherein the PEM has a proton conductivity at 50°C of 0.10 S cm'1or greater.

15. The PEM of claim 1, wherein the PEM has a proton conductivity at 80°C of 0.15 S cm'1or greater.

16. The PEM of claim 15, wherein the proton conductivity at 80°C is 0.20 S cm'1or greater.

17. The PEM of claim 1, wherein the PEM has an effective proton mobility at 80°C of greater than 0.050 x 10'5cm2s'1V'1.

18. The PEM of claim 1, wherein the PEM has a methanol permeability of less than or equal to 1.5 x 10'6cm2s'1.

19. A membrane electrode assembly (MEA), comprising: an anode; a cathode; and a PEM disposed between the anode and the cathode, wherein the PEM is the PEM of any one of claims 1-18.

20. A fuel cell comprising: an electrochemical cell comprising the membrane electrode assembly of claim 19.

21. The fuel cell of claim 20, wherein the fuel cell is a direct methanol fuel cell.

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