Tetra-coordinated Boronic Acid Functionalized Polymers

Description

1 / 88 Polymers functionalized with tetracoordinate boronic acid. Related Orders

[001] This application claims priority over U.S. Provisional Patent Application 63 / 444,772, filed February 10, 2023, and U.S. Provisional Patent Application 63 / 624,533, filed January 24, 2024, each of which is incorporated herein by reference in its entirety. Fundamentals of the Invention

[002] In electrochemical cells, such as hydrogen fuel cells and water electrolysis systems, proton exchange membranes (PEMs) are used to selectively transport protons. Proton exchange membranes (PEMs) are semipermeable membranes that transport protons (H+) while being impermeable to gases. PEMs are generally composed of a porous structure with highly acidic functional groups. For example, polyfluorosulfonic acid-based PEMs, such as Nafion™ (The Chemours Company, Wilmington, Delaware) and No present documentvion® (Solvay SA Corporation, Brussels, Belgium), contain a porous poly(tetrafluoroethylene) (PTFE) structure with pendant sulfonic acid side groups. The readily dissociable sulfonic acid groups act as proton transport agents in the membrane. In cells a Petition 870250090980, dated 06 / 10 / 2025, page 9 / 112 2 / 88 Hydrogen fuel, hydrogen gas (H2) splits at the anode into protons (H+) and electrons. The protons undergo an EMP and combine with oxygen gas (O2) at a cathode to produce water, while the electrons flow through an external circuit to produce electricity. In water electrolysis systems, electricity splits the water at the anode into oxygen gas (O2) and protons (H+). The protons undergo an EMP and combine with electrons at the cathode to produce hydrogen gas (H2).

[003] A membrane electrode array (MEA) may include a PEM positioned between a first catalyst layer and a second catalyst layer. The catalyst layers are electrically conductive electrodes (anode and cathode) with embedded electrochemical catalysts, such as metals, metal alloys, or metal oxides. The catalysts may be bonded to a solid catalyst support, which is usually a high surface area electrically conductive carbon (e.g., graphite or graphene). The electrochemical catalysts reduce the activation energy required to carry out electrochemical reactions at the electrodes, such as the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) in water electrolysis applications and the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (HOR) in fuel cell applications. Petition 870250090980, dated 06 / 10 / 2025, page 10 / 112 3 / 88

[004] In some applications, the catalyst layer includes a supported catalyst mixed with an ionomer, an ion-conducting polymer. The ionomer binds the catalysts at the electrode, binds the catalyst layer to the PEM, and provides a pathway for cations (e.g., protons), thus improving cationic conductivity. In some MEAs, the catalyst layers are formed separately from the PEM and arranged over the PEM in the MEA stack. In other MEAs, the catalyst layers are coated over the PEM to form catalyst-coated membranes (CCMs).

[005] Applications in water electrolysis and fuel cells involve strong chemical oxidation and reduction processes under acidic conditions and at ambient to high temperatures. Therefore, PEMs and ionomers, and the molecular functional groups present in them, responsible for proton transport properties, must remain robust under the severe conditions of redox stress reactions. However, conventional polymers used in PEMs and as ionomers, such as Nafion™ No present documentvion®, mainly contain sulfonic acid functional groups as proton transport agents. Sulfonic acid functional groups have limited capacity to withstand the redox stress of electrochemical operations, mainly due to the intrinsic physicochemical properties of sulfur. Furthermore, the acid groups Petition 870250090980, dated 06 / 10 / 2025, page 11 / 112 4 / 88 sulfonic acids participate in secondary redox reactions, promoting catalyst poisoning by platinum group metals and depolymerization of polymer matrices. Brief Description of the Drawings

[006] The attached drawings illustrate various embodiments and form part of the descriptive report. The embodiments illustrated are merely examples and do not limit the scope of the description. Throughout the drawings, identical or similar reference numbers designate identical or similar elements.

[007] Figure 1A shows an illustrative reaction scheme for the synthesis of a PBI polymer functionalized with boronic acid.

[008] Figure 1B shows an illustrative reaction scheme for the synthesis of a boronic acid-functionalized PBI polymer by borylation.

[009] Figure 2A shows an illustrative reaction scheme for the synthesis of a boronic acid-functionalized polystyrene polymer by borylation.

[0010] Figure 2B shows an illustrative reaction scheme for the synthesis of a boronic acid-functionalized polymer using a vicinal diol.

[0011] Figure 3A shows an illustrative reaction scheme for the synthesis of a boronic acid functionalized polymer replacing a sulfonic acid group. Petition 870250090980, dated 06 / 10 / 2025, page 12 / 112 5 / 88 suspended by a group of boronic acid.

[0012] Figure 3B shows an illustrative reaction scheme for the synthesis of a boronic acid-functionalized polymer by replacing a pendant sulfonic acid group with a boronic acid group.

[0013] Figures 4A-4C show illustrative reaction schemes for synthesizing a fluoroboric acid functionalized polymer by performing a fluoride treatment of a boronic acid functionalized polymer.

[0014] Figures 5A and 5B show alternative illustrative reaction schemes for synthesizing a fluoroboric acid functionalized polymer by performing a fluoride treatment of a boronic acid functionalized polymer.

[0015] Figures 6 and 7 show illustrative reaction schemes for the synthesis of a PBI polymer functionalized with fluoroboric acid, performing a fluorine treatment on a PBI polymer functionalized with boronic acid.

[0016] Figures 8 and 9 show alternative illustrative reaction schemes for synthesizing a fluoroboric acid-functionalized PBI polymer by performing a fluoride treatment of a boronic acid-functionalized PBI polymer.

[0017] Figures 10A and 10B show illustrative reaction schemes for synthesizing a polymer functionalized with Petition 870250090980, dated 06 / 10 / 2025, page 13 / 112 6 / 88 fluoroboric acid polystyrene, performing a fluoride treatment of a polystyrene polymer functionalized with boronic acid.

[0018] Figures 11A and 11B show illustrative reaction schemes for synthesizing a fluoroboric acid functionalized polymer by performing a fluoride treatment of a boronic acid functionalized polymer.

[0019] Figures 12 and 13 show alternative illustrative reaction schemes for synthesizing a fluoroboric acid functionalized polymer by performing a fluoride treatment of a boronic acid functionalized polymer.

[0020] Figure 14 shows another illustrative reaction scheme for synthesizing a polymer functionalized with fluoroboric acid.

[0021] Figure 15 shows an illustrative proton exchange membrane water electrolysis system incorporating polymer PEMs functionalized with fluoroboric acid and / or ionomers.

[0022] Figure 16 shows an illustrative proton exchange membrane fuel cell, including polymer PEMs functionalized with fluoroboric acid and / or ionomers. Detailed Description

[0023] A polymer molecule functionalized with Petition 870250090980, dated 06 / 10 / 2025, page 14 / 112 7 / 88 Tetra-coordinated boronic acid includes a main chain, a side chain or a side group attached to the main chain, and a pendant tetra-coordinated boronic acid group on a side chain or side group. The pendant tetra-coordinated boronic acid group includes a tetra-coordinated boron atom with a formal negative charge and counterbalanced by a cation (e.g., a proton). The tetra-coordinated boronic acid-functionalized polymer can be formed by post-polymerization functional modification of a boronic acid-functionalized polymer, such as a boronic acid-functionalized PBI polymer, polystyrene polymer, or PTFE polymer.

[0024] Tetra-coordinated boronic acid functionalized polymers, as described herein, can be used in electrochemical cell applications, such as in PEMs, ionomers, catalyst layers, and membrane electrode assemblies (MEAs). Ionomers and PEMs based on tetra-coordinated boronic acid functionalized polymers reduce or eliminate catalyst poisoning compared to sulfonic acid functionalized polymers. In some examples, tetra-coordinated boronic acid functionalized polymers comprise tetra-coordinated boronic acid functionalized PTFE polymers, which are highly effective PTFE polymers for PEM and ionomer applications while maintaining the Petition 870250090980, dated 06 / 10 / 2025, page 15 / 112 8 / 88 characteristics of Nation™ and in the present documentvion® remain intact, while reducing or eliminating the controversial issues of catalyst poisoning and depolymerization (polymer instability). Unlike conventional polymers comprising pendant sulfonic acid groups, tetra-coordinated boronic acid-functionalized polymers remain stable without polymer decompaction (i.e., depolymerization) under the demanding electrochemical conditions of water electrolysis and hydrogen fuel cells.

[0025] Several definitions will now be provided to aid in understanding various aspects of the present description. As used herein, each term or expression, for example, alkyl, m, n, etc., when used more than once, is intended to be independent of its definition elsewhere in this description. In case of conflict with any patent application or patent incorporated herein by reference, this specification, including the definitions, shall prevail.

[0026] As used in this document, polymer refers to a substance comprising polymer molecules of the same or different species of polymer, including a mixture of polymer molecules of the same species of polymer which may differ from other polymer molecules in the same sample in length. Petition 870250090980, dated 06 / 10 / 2025, page 16 / 112 9 / 88 chain, and / or particular structural arrangement (e.g., irregularities in the orientation of monomer units, end groups, and / or in the locations and / or lengths of any side chains or side groups). Polymer includes homopolymers, copolymers, terpolymers, interpolymers, and so forth.

[0027] As used in this document, polymer molecule or macromolecule refers to a molecule of high relative molecular weight whose structure comprises a relatively large repetition of units (e.g., about 100 or more monomer units) derived, actually or conceptually, from molecules of low relative molecular weight (e.g., monomeric molecules).

[0028] As used in this document, polymerization refers to the process of converting a monomer, or a mixture of monomers, into a polymer.

[0029] As used in this document, oligomer refers to a substance composed of oligomer molecules.

[0030] As used in this document, an oligomer molecule refers to a molecule of intermediate relative molecular mass, whose structure comprises a relatively small repetition of units (e.g., about 5 to about 100 monomer units). Petition 870250090980, dated 06 / 10 / 2025, page 17 / 112 10 / 88 derived, actually or conceptually, from molecules of lower relative molecular mass (e.g., monomeric molecules).

[0031] As used in this document, oligomerization refers to the process of converting a monomer or a mixture of monomers into an oligomer.

[0032] The principles, concepts, and characteristics described herein with reference to polymers, polymer molecules, and polymerization apply equally to oligomers, oligomer molecules, and oligomerization, respectively. Therefore, all uses of the terms polymer, polymer molecule, and polymerization described herein may be replaced by the terms oligomer, oligomer molecule, and oligomerization, respectively, without departing from the scope of the description herein.

[0033] As used in this document, ionomer refers to a polymer composed of ionomer molecules.

[0034] As used herein, ionomer molecule refers to a polymer molecule in which a small but relatively significant proportion of the constitutional units have ionizable or ionic pendant groups (including the ion-exchange groups described herein), or both. In general, Petition 870250090980, dated 06 / 10 / 2025, page 18 / 112 11 / 88 No more than approximately 15 mole percent of the constitutional units have ionizable or ionic pendant groups.

[0035] As used in this document, “monomer” refers to a substance composed of monomeric molecules.

[0036] As used in this document, “monomer molecule” refers to a molecule that can undergo polymerization or oligomerization to form a polymer molecule or an oligomer molecule. A monomer molecule contributes constituent units to the essential structure of a polymer molecule or an oligomer molecule.

[0037] As used in this document, “copolymer” refers to a polymer derived from more than one type of monomer.

[0038] As used in this document, “constitutional unit” refers to an atom or group of atoms (with dangling atoms or groups, if any) comprising a part of the structure of a polymer molecule (or oligomer molecule, block or chain).

[0039] As used in this document, “repeating unit” refers to the constitutional unit whose repetition constitutes a polymer molecule (or oligomer molecule, block or chain). Petition 870250090980, dated 06 / 10 / 2025, page 19 / 112 12 / 88 As used in this document, "monomer unit" refers to the largest constitutional unit contributed by a single monomer molecule to the structure of a polymer molecule or an oligomer molecule.

[0040] As used in this document, “block” refers to a portion of a polymer molecule (or oligomer molecule) comprising many constitutional units and exhibiting at least one feature that is not present in adjacent portions.

[0041] As used in this document, “chain” refers to all or part of a polymer molecule (or oligomer molecule or block), comprising a linear or branched sequence of constitutional units between two boundary constitutional units, each of which may be a terminal group, a branching point or an otherwise designated feature of the polymer molecule.

[0042] As used in this document, “main chain” or “main structure” refers to the chain of a polymer molecule to which all other chains (long, short, or both) can be considered to be attached (e.g., a side chain).

[0043] As used in this document, “side chain” refers to an oligomeric (short chain) or polymeric (long chain) unfolding of the main chain of Petition 870250090980, dated 06 / 10 / 2025, p. 20 / 112 13 / 88 a polymer molecule.

[0044] As used in this document, “side group” or “pendant group” refers to a split, neither oligomeric nor polymeric, of a chain (e.g., a main chain).

[0045] The principles, concepts and characteristics described in this document with reference to side chains apply equally to side groups. Consequently, any use of the term side chain may be replaced by the term side group without departing from the scope of this description.

[0046] As used in this document, “crosslinking” refers to a small region in a polymer molecule from which at least four chains emanate. A crosslink is generally formed by reactions involving sites or groups on existing polymer molecules or by interactions between existing polymer molecules.

[0047] The term “crosslinked” refers to the state in which polymer molecules, which were previously separate polymer molecules, are linked to each other at different points on their ends, usually by covalent bonds.

[0048] As used in this document, a “catalyst particle” refers to a particle in “black” or pure form (i.e., excluding any catalyst carrier to which the catalyst particle may be attached). Petition 870250090980, dated 06 / 10 / 2025, p. 21 / 112 14 / 88 (linked and excluding any catalyst additives) that increases the rate of a reaction without modifying the overall standard Gibbs free energy change in the reaction. A catalyst particle may be an individual molecule (including, but not limited to, a monomer molecule), a group of molecules, a crystalline structure (e.g., as in a metal oxide), a polymer molecule, or an oligomer molecule. A catalyst particle may have any suitable size and shape, such as a microparticle, a nanoparticle, or a nanotube. A catalyst particle may include, for example, a metal, a metal alloy, a metal oxide, a metal halide (e.g., a metal chloride), or a composite including at least one of a metal, a metal alloy, a metal oxide, or a metal halide.

[0049] As used herein, an “electrocatalyst particle” or “electrochemical catalyst particle” refers to a catalyst particle that reduces the activation energy required to carry out electrochemical reactions and / or increases the rate of electrochemical reactions, such as OER, HER, HOR and / or ORR. Suitable electrocatalyst particles may include, without limitation, metals such as platinum group metals (PGMs) (e.g., platinum, palladium, iridium, ruthenium, osmium and rhodium), transition metals (e.g., silver, gold, Petition 870250090980, dated 06 / 10 / 2025, page 22 / 112 15 / 88 cobalt, copper, iron, nickel, rhenium and mercury) and post-transition metals (e.g., bismuth and tin), metal alloys (e.g., PGM-transition metal based alloys and platinum-ruthenium based alloys), metal oxides (e.g., PGM oxides, such as iridium(IV) oxide, ruthenium(IV) oxide, iridium-ruthenium oxide, platinum(IV) oxide, magnesium oxide and cerium(IV) oxide), metal halides (e.g., platinum(IV) chloride, iridium(III) chloride, platinum(IV) bromide, iridium(III) bromide and / or metal composites, metal alloys, metal oxides and / or metal halides.

[0050] As used herein, a “catalyst support” refers to a substance, excluding a catalyst particle, that can be used to support catalyst particles (e.g., a substance or material to which catalyst particles can be attached or on which catalyst particles can be supported). Examples of catalyst supports include, without limitation, carbon-based materials (e.g., carbon black, graphite, carbon nanotubes, graphene and / or boron-functionalized carbon materials described herein), titanium dioxide, Sb-doped SnO2 nanoparticles, tin-doped indium oxide (ITO) and / or the ion-exchange modified catalyst supports described in the International Patent Application. Petition 870250090980, dated 06 / 10 / 2025, page 23 / 112 16 / 88 PCT / US2022 / 046105, filed on October 7, 2022, the contents of which are incorporated herein by reference in their entirety.

[0051] As used in this document, a catalyst refers to a catalyst particle as well as to a catalyst particle together with a catalyst carrier on which the catalyst particle is supported or to which the catalyst particle is attached. A catalyst may also include catalyst additives, such as promoters (such as, but not limited to, metalloids).

[0052] As used in this document, an electrocatalyst or electrochemical catalyst refers to an electrocatalyst particle in black or pure form, as well as to an electrocatalyst particle together with a catalyst carrier on which the electrocatalyst particle is supported or to which the catalyst particle is attached. An electrocatalyst may also include catalyst additives, such as promoters.

[0053] As used in this document, metal includes alkali metals, alkaline earth metals, transition metals, lanthanides, actinides and post-transition metals.

[0054] As used in this document, transition metals refer to elements in the d-block of the periodic table (Groups 3 to 12 inclusive). Petition 870250090980, dated 06 / 10 / 2025, page 24 / 112 17 / 88

[0055] As used in this document, “post-transition metals” refers to aluminum, gallium, indium, tin, thallium, lead, bismuth, and polonium.

[0056] As used in this document, “metalloids” refers to boron, silicon, germanium, arsenic, antimony, tellurium and astatine.

[0057] As used in this document, “platinum group metals” or “PGMs” refers to platinum, palladium, iridium, ruthenium, osmium and rhodium.

[0058] As used in this document, “aliphatic” compounds are saturated or unsaturated hydrocarbons, acyclic or cyclic, branched or unbranched, unsubstituted or wholly or partially substituted by one or more substituents or functional groups. As will be understood by those skilled in the art, the term “aliphatic” includes, but is not limited to, alkyl, alkenyl, and alkynyl moieties. Illustrative aliphatic groups include, but are not limited to, for example, methyl, ethyl, n-propyl, isopropyl, allyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, tert-pentyl, n-hexyl, and sec-hexyl moieties.

[0059] As used in this document, the term “alkyl” receives its common meaning in the art and may include saturated aliphatic groups, including linear chain alkyl groups, chain alkyl groups Petition 870250090980, dated 06 / 10 / 2025, p. 25 / 112 18 / 88 branched, cycloalkyl (alicyclic) groups, alkyl-substituted cycloalkyl groups, and cycloalkyl-substituted alkyl groups. A similar convention applies to other generic terms such as alkenyl, alkynyl, and the like. Furthermore, as used herein, the terms alkyl, alkenyl, alkynyl, and the like include both fully or partially substituted and unsubstituted groups.

[0060] In some embodiments, a linear or branched alkyl chain may have from 1 to 30 carbon atoms in its main chain and, in some cases, from 1 to 20 or less. In some embodiments, a linear or branched alkyl chain has from 1 to 10 carbon atoms in its main chain (e.g., C1-C10 for linear chain, C3-C10 for branched chain), has 6 or fewer carbon atoms, or has 4 or fewer carbon atoms. Cycloalkyls may have from 3 to 10 carbon atoms in their ring structure or, in some cases, from 3 to 5, 6, or 7 carbon atoms in the ring structure. Examples of noncyclic alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, n-butyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, n-heptyl, noctyl, n-decyl, n-undecyl, and dodecyl. Examples of cyclic alkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, and cyclohexyl. Petition 870250090980, dated 06 / 10 / 2025, p. 26 / 112 19 / 88

[0061] The terms alkenyl and alkynyl refer to unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but containing at least one double or triple bond, respectively. Alkenyl groups include, but are not limited to, ethenyl, propenyl, butenyl, 1-methyl-2-buten-1-yl and the like. Non-limiting examples of alkynyl groups include ethinyl, 2-propynyl (propargyl), 1-propynyl and the like.

[0062] The term heteroalkyl refers to an alkyl group in which one or more hydrogen atoms bonded to any carbon of the alkyl group or one or more carbon atoms are replaced by a heteroatom. A heteroatom is any atom other than carbon. In some examples, a heteroatom is an atom selected from the group consisting of N, O, P, B, S, Si, Sb, Al, Sn, As, Se, and Ge. Examples of heteroalkyl groups include, without limitation, methoxy, ethoxy, propoxy, isopropoxy, methylthio, ethylthio, propylthio, isopropylthio, n-butylthio, methoxymethyl, and cyano groups.

[0063] The terms heteroalkenyl and heteroalkynyl refer to unsaturated aliphatic groups analogous in length and possible substitution to the heteroalkyls described above, but containing at least one double or triple bond, respectively.

[0064] The term aryl refers to carbocyclic groups Petition 870250090980, dated 06 / 10 / 2025, p. 27 / 112 20 / 88 Aromatic compounds, unsubstituted or fully or partially substituted, having a single ring (e.g., phenyl), multiple rings (e.g., biphenyl), or multiple fused rings, in which at least one ring is aromatic (e.g., 1,2,3,4-tetrahydronaphthyl, naphthyl, anthryl, or phenanthryl). That is, at least one ring may have a conjugated Pi electron system, while other adjacent rings may be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, and / or heterocyclyls. “Carbocyclic aryl groups” refers to aryl groups in which the aromatic ring atoms are carbon atoms. Carbocyclic aryl groups include monocyclic aryl groups and polycyclic or fused compounds (e.g., two or more adjacent ring atoms are common to two adjacent rings), such as the naphthyl group. Examples of aryl groups include, but are not limited to, phenyl, naphthyl, tetrahydronaphthyl, indanyl, and indenyl.

[0065] The term “heteroaryl” refers to aryl groups comprising at least one heteroatom as a ring atom, such as a heterocycle. Non-limiting examples of heteroaryl groups include, without limitation, pyridyl, pyrazinyl, pyrimidinyl, pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, isooxazolyl, thiadiazolyl, oxadiazolyl, thiophenyl, furanyl, quinolinyl, and isoquinolinyl.

[0066] The terms “alcoxi” or “alcoxi”, in the manner of Petition 870250090980, dated 06 / 10 / 2025, p. 28 / 112 21 / 88 of this document, used, refer to an alkyl group with an oxygen radical attached to it and have the general formula R—O. Examples of alkoxy groups include, without limitation, methoxy, ethoxy, propyloxy and tert-butoxy groups.

[0067] The term aryloxy refers to an aryl group with an oxygen radical attached to it. An example of an alkoxy group includes, without limitation, a phenoxy group.

[0068] Any of the previous groups may be optionally replaced, in whole or in part. Examples of substituents include, without limitation, aliphatic, alicyclic, heteroaliphatic, heteroalicyclic, halogens, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxyl, amino, nitro, sulfhydryl, imino, amido, phosphonate, phosphinate, carbonyl, carboxyl, alkyloxycarbonyl, silyl, ether, alkylthio, heteroalkylthio, heteroarylthio, sulfonyl, sulfonamido, ketone, aldehyde, ester, heterocyclyl, aromatic or heteroaromatic fractions, —CF3, —CN, aryl, aryloxy, per-haloalkoxy, aralkoxy, heteroaryl, heteroaryloxy, heteroarylalkyl, heteroaralkoxy, azido, amino, halide, alkylthio, oxo, acylalkyl, carboxylic esters, -carboxamido, acyloxy, aminoalkyl, alkylaminoaryl, alkylaryl, alkylaminoalkyl, alkoxyaryl, arylamino, aralkylamino, alkylsulfonyl, -carboxamidoalkylaryl, carboxamidoaryl, hydroxyalkyl, haloalkyl, Petition 870250090980, dated 06 / 10 / 2025, p. 29 / 112 22 / 88 alkylaminoalkylcarboxy-, aminocarboxamidoalkyl-, cyano, alkoxyalkyl, perhaloalkyl, arylalkyloxyalkyl, (e.g., SO4(R')2), a phosphate (e.g., POUR')3), a silane (e.g., Si(R')4), a urethane (e.g., R'O(CO)NHR') and the like. In addition, substituents may be selected from F, Cl, Br, I, —OH, —NO2, —CN, —NCO, —CF3, —CH2CF3, —CHCl2, —CH2ORx, —CH2CH2ORx, —CH2N(Rx)2, —CH2SO2CH3, —C(O)Rx, —O2(Rx), —CON(Rx)2, —OC(O)Rx, — C(O)OC(O)Rx, —OCO2Rx, —OCON(Rx)2, —N(Rx)2, —S(O)2Rx, —OCO2Rx, —NRx(CO)Rx, —NRx(CO)N(Rx)2, wherein each occurrence of Rx includes independently, but without limitation, hydrogen, aliphatic, alicyclic, heteroaliphatic, heteroalicyclic, aryl, heteroaryl, alkylaryl or alkylheteroaryl, wherein any of the aliphatic, alicyclic, heteroaliphatic, heteroalicyclic, alkylaryl or alkylheteroaryl substituents described above and herein may be wholly or partially substituted or unsubstituted, branched or unbranched, cyclic or acyclic, and wherein any of the aryl or heteroaryl substituents described above and herein may be wholly or partially substituted or unsubstituted.

[0069] Tetra-coordinated boronic acid functionalized polymers, such as fluoroboric acid functionalized polymers, as described in this document. Petition 870250090980, dated 06 / 10 / 2025, page 30 / 112 23 / 88 described, can be used in PEM and ionomer applications. In some examples, tetra-coordinated boronic acid functionalized polymers are synthesized by post-polymerization functional modification of PEM polymers, such as polybenzimidazole (PBI) polymers, sulfonic acid-functionalized PTFE polymers, polystyrene polymers, and / or boronic acid-functionalized derivatives of any of the above polymers.

[0070] Polybenzimidazole (PBI) polymers are a class of polymers composed of PBI polymer molecules. PBI polymer molecules have a repeating unit that includes a benzimidazole unit as at least part of a back chain. The benzimidazole unit comprises a benzimidazole moiety or a derivative thereof. Benzimidazole is a heterocyclic aromatic organic compound that has a phenyl group and an imidazole group sharing two carbon atoms in their ring structures. The overall structure of benzimidazole is shown in the following Formula (I): H aN NZ(D

[0071] An example of a PBI polymer with a unit of Petition 870250090980, dated 06 / 10 / 2025, page 31 / 112 24 / 88 benzimidazole per repeating unit in a main chain is poly(2,5-benzimidazole) (AB-PBI), shown below as Formula (II), and examples of PBI polymers with two benzimidazole units per repeating unit in a main chain are poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (m-PBI), shown below as Formula (III), and 4F-PBI (a fluorinated derivative of m-PBI), shown below as Formula (IV). (II): AB-PBI (III): m-PBI

[0072] Other examples of PBI polymers include, without Petition 870250090980, dated 06 / 10 / 2025, page 32 / 112 25 / 88 limitation, poly{2,6-(2,6-naphthylidene)-1,7-di-hydrobenzo[1,2d;4,5-d']diimidazole}; poly 2,2'-(2,6-naphthylidene)-5,5'bibenzimidazole; poly-2,2'-(2,6-pyridine)-5,5'bibenzimidazole; poly-2,2'-(2,5-pyridine) 5,5'bibenzimidazole; poly-2,2'-(2,2'-bipyridine-5,5')-5,5'bibenzimidazole); poly-2,2'-(3,5-pyrazole)-5,5'bibenzimidazole; poly-2,2'-(m-phenylene) -5,5'-bibenzimidazole; poly-2,2'-(pyridylene-3, 5)-5,5'-bibenzimidazole; poly2,2'-(furylene-2,5)-5,5'-bibenzimidazole; poly-2.2(naphthalene-1,6)-5,5'-bibenzimidazole; poly-2,2'(biphenylene-4,4)-5,5'-bibenzimidazole; poly-2,2'-amylene5,5'-bibenzimidazole; poly-2,2'-octamethylene-5,5'bibenzimidazole; poly-2,6-(m-phenylene)-diimidazolebenzene; poly-2,2'-cyclohexenyl-5,5'-bibenzimidazole; poly-2,2'-(mphenylene)-5.5'di(benzimidazole)ether; poly-2,2'-(m-phenylene)5,5-di(benzimidazole)sulfide; poly-2,2'-(m-phenylene)-5,5di(benzimidazole)sulfone; poly-2,2'-(m-phenylene)-5,5di(benzimidazole)methane; poly-2,2-(m-phenylene)-5,5(di(benzimidazole)propane 2,2); poly-2,2-(m-phenylene)-5',5di(benzimidazole)ethylene-1,2; and derivatives of any of the foregoing (including substituted (e.g., fluorinated) and / or branched derivatives). In some examples, a PBI polymer is a copolymer comprising one or more additional repeating units, which may or may not include a benzimidazole unit in a back chain, in a Petition 870250090980, dated 06 / 10 / 2025, page 33 / 112 26 / 88 side chain, or both.

[0073] Polytetrafluoroethylene (PTFE) polymers are a class of polymers composed of tetrafluoroethylene polymer molecules and derivatives thereof, and are produced by the polymerization of tetrafluoroethylene. PTFE polymer molecules have a carbon backbone with two fluorine atoms bonded to each carbon and derivatives thereof.

[0074] Polychlorotrifluoroethylene (PCTFE) polymers are derived from PTFE and are homopolymers of chlorotrifluoroethylene (CTFE) with the molecular formula (CF2CClF)ne and its derivatives. PCTFE is similar to PTFE (such as Teflon), except that it contains a chlorine atom in each repeating unit. The presence of this chlorine atom makes PCTFE a unique thermoplastic polymer with diverse applications. However, PCTFE has a hydrophobic back chain and is not ion-conductive, therefore it is not suitable for electrochemical applications. PCTFE polymer derivatives include substituent groups (e.g., side chains or side groups) in place of chlorine atoms. PCTFE derivatives may be fully or partially substituted. PCTFE polymer derivatives include, without limitation, modified and functionalized PCTFE polymers, including any of the modified or functionalized PCTFE polymers (e.g., polymers Petition 870250090980, dated 06 / 10 / 2025, page 34 / 112 27 / 88 of acid-functionalized and ion-exchange functionalized PCTFEs) described in US Provisional Application 63 / 532,262, filed on August 11, 2023, which is incorporated herein by reference in its entirety.

[0075] Sulfonic acid-functionalized PTFE polymers are derived from PTFE polymers and have a PTFE back chain and a side chain or side group with one or more pendant sulfonic acid groups. In some examples, the side chain is a long side chain (LSC) with at least two ether linkages and four or more polyfluorinated carbon units (e.g., —CF2— and / or —CF3). In other examples, the side chain is a short side chain (SSC) with one ether linkage and two polyfluorinated carbon units. In other examples, the side chain is a medium side chain (MSC) with one ether linkage and four polyfluorinated carbon units. In some examples, a PTFE polymer functionalized with sulfonic acid has the general formula [(CF2CF2)m(CFACF2)n]x, where A is a side chain comprising one or more pendant sulfonic acid groups, and en and nex are positive and are selected based on application, equivalent weight, molecular weight, etc.In some examples, m varies from 4 to 7 and n is 1. In some examples, side chain A is an LSC, MSC, or SSC. Examples of acid-functionalized PTFE polymers. Petition 870250090980, dated 06 / 10 / 2025, p. 35 / 112 28 / 88 sultonic acid LSCs include, without limitation, polymers of the Nation™ series (available from Chemours Company in various configurations and grades, including Nation-H, Nation HP, Nation 117, Nation 115, Nation 212, Nation 211, Nation NE1035, Nation XL, etc.) and any combination, derivative, grade, or configuration thereof. Examples of PTFE polymers functionalized with sultonic acid SSCs include, but are not limited to, polymers of the No present documentvion® series (available from Solvay SA in different configurations and grades, including No present documentvion® E98-05, No present documentvion® PW98, No present documentvion® PW87S, etc.), Gore-Select® (available from WL Gore & Associates, Inc.), Flemion™ (available from Asahi Glass Company), Pemion+™ (available from Ionomr Innovations, Inc.) and any combination, derivative, grade or configuration thereof. Examples of PTFE polymers functionalized with sulfonylurea MSC include, but are not limited to, polymers produced by 3M™ Company. In some examples, a PTFE polymer is a copolymer comprising one or more repeating units. In some examples, a PTFE polymer may be doped and / or crosslinked with itself and / or with another polymer.

[0076] Polymers functionalized with sultonic acid include, without limitation, polyfluorosultonic acid polymers and non-fluorinated sultonic acid polymers. Examples of sultonic acid polymers Petition 870250090980, dated 06 / 10 / 2025, page 36 / 112 29 / 88 Polyfluorosulfonic acids include, without limitation, PTFE polymers functionalized with sulfonic acid and PCTFE polymers functionalized with sulfonic acid. Examples of non-fluorinated sulfonic acid polymers include, without limitation, poly(styrene sulfonic acid) polymers, sulfonated aromatic polymers (e.g., sulfonated poly(ether ketone) polymers (SPEEK), sulfonated poly(aryl ether sulfone) polymers (SPAES), sulfonated poly(arylene ether ketone) polymers (SPAEK), sulfonated polysulfone polymers (SPSF), sulfonated polyimide polymers (SPI) and sulfonated polystyrene (SPS), sulfonated polyphenylene and any other sulfonated polymer, including sulfonated derivatives of polymers described herein.

[0077] Polystyrene polymers are polymers composed of polystyrene polymer molecules. Polystyrene polymer molecules have a repeating unit that includes alternating carbon centers bonded to a phenyl group. Examples of polystyrene polymers include, without limitation, polystyrene, poly(styrene sulfonic acid) (e.g., poly(4-styrene sulfonic acid)), polyhalostyrene, poly(3-trifluoromethyl styrene), poly(4-acetoxy styrene), poly(4-allyl styrene), poly(4-cyanostyrene), poly(4-dimethylsilyl styrene), poly(4-hydroxystyrene), poly(alpha-methyl styrene), poly(4-methyl styrene), poly(4-methoxystyrene), poly(4-[tercPetição 870250090980, dated 06 / 10 / 2025, page 37 / 112 30 / 88 butoxycarbonyl]oxystyrene), poly(4-tert-butyl styrene), poly(4-[N,N-di(trimethylsilyl)aminomethyl]-styrene), poly(4-vinylbenzoic acid), poly(n-butyl 4-vinylbenzoate), poly(tert-butyl 4-vinylbenzoate), poly(2-ethylhexyl 4-vinylbenzoate), poly(methyl 4-vinylbenzoate), poly(vinylbenzyl chloride), poly(4-vinylbenzyl-N-methylphthalimide), poly(vinylcyclohexane) and derivatives of any of the foregoing (including substituted (e.g., fluorinated) and / or branched derivatives). In some examples, a polystyrene polymer is a copolymer comprising one or more additional repeating units, which may or may not include a carbon center bonded to a phenyl group.

[0078] Aromatic polymers include any polymers that have aromatic rings in a main chain and / or in side chains or side groups. Examples of aromatic polymers include, without limitation, polystyrene polymers, polycarbonate polymers (polyphenylene polymers (e.g., poly(1,4-phenylene), poly(1,4-phenylene-ethylene), poly(1,3-phenylene-methylene), poly(p-phenylene vinylidene), poly(p-phenylene vinylene), poly(1,4-phenylene oxide), poly(1,4-phenylene sulfide)), poly(ether sulfone), polyaryletherketone polymers, polysulfone polymers, poly(ethylene terephthalate), aromatic polyester polymers, poly(oxy-1,4-phenylene carbonyl-1,4-phenylene), poly[(dimethylmethylene)bis(4,1-phenylene) Petition 870250090980, dated 06 / 10 / 2025, page 38 / 112 31 / 88 carbonate], phenolic resins, poly[(ethylazanediyl)ethyleneazanediyl-1,3-phenylene], polyoxydiphenylenepyromellitimide (Kapton®, manufactured by EI du Pont de Nemours and Company), poly(imide ester) polymers, aromatic polyimide polymers, lignin and derivatives of any of the above (including substituted (e.g., fluorinated) and / or branched derivatives).

[0079] Natural polymers (also called biopolymers) include, without limitation, cellulose, lignin, chitin, and derivatives of any of the above, including any of the polymers described in U.S. Patent 11,331,631, issued May 17, 2022, and U.S. Patent 11,594,747, issued February 28, 2023, each of which is incorporated herein by reference in its entirety.

[0080] Boronic acid-functionalized polymers can be used for the synthesis of tetra-coordinated boronic acid-functionalized polymers, as described in more detail below. A boronic acid-functionalized polymer molecule includes a main chain polymer and a boronic acid group pendant on the main chain or on a side chain or side group. The boronic acid group has the general formula —B(OH)2 or =B(OH)2, where the boron atom is covalently bonded to one or two hydroxyl groups and by one or two covalent bonds to Petition 870250090980, dated 06 / 10 / 2025, page 39 / 112 32 / 88 main chain or side chain, with three covalent linkages in total. Examples of boronic acid-functionalized polymers include, without limitation, PBI polymer derivatives, sulfonic acid-functionalized PTFE polymers, sulfonic acid-functionalized PCTFE polymers, sulfonic acid-functionalized polymers, polystyrene polymers, and cellulose polymers functionalized with boronic acid groups. Illustrative reaction schemes for the synthesis of boronic acid-functionalized polymers will now be described.

[0081] In some examples, a boronic acid-functionalized polymer is formed by post-polymerization functional modification of a polymer molecule. Several examples of post-polymerization functional modification will now be described.

[0082] In some examples, a boronic acid-functionalized PBI polymer is synthesized by post-polymerization functional modification of a PBI polymer, coupling a boronic acid-functionalized linker to a secondary nitrogen atom in the benzimidazole moiety of the PBI polymer. The boronic acid-functionalized linker has an X linking group as a terminal or side group and a boronic acid group as a terminal and / or side group, where the X linking group is a methyl group (—CH3), a formyl group (—C(=O)H), or a group Petition 870250090980, dated 06 / 10 / 2025, page 40 / 112 33 / 88 sulfonyl (—S(=O) 2H) . In some examples, the ligand functionalized with boronic acid has the general formula XRB(OH)2, where R is an alkyl chain of length m, where m varies from 0 to 30 (or from 0 to 20, or from 0 to 12, or from 0 to 10, or from 0 to 8, or from 0 to 6) and has one or more side groups A, each of which can independently be hydrogen (H), a hydroxyl group (OH), a fluoro group (F), a chlorine group (Cl), a boronic acid group, a dialkylamino group (NR'2, where R' can represent hydrogen or an organic combining group, such as a methyl group (CH3)), a cyano group (CN), a carboxylic acid group (COOH), a carboxylic amide group, an ester group, an alkyl group, an alkoxy group, or an aryl group. In some examples, the boronic acid-functionalized ligand has one or more pendant boronic acid groups as a side group instead of or in addition to a terminal group.

[0083] In the reaction, the X linking group of the boronic acid-functionalized ligand binds to the secondary nitrogen of the benzimidazole moiety, thus forming a side chain with a pendant boronic acid group. The charge of the boronic acid groups can be controlled by adjusting the molar ratio of the boronic acid-functionalized ligand to the benzimidazole moiety in the PBI polymer.

[0084] Figure 1A shows an illustrative reaction scheme for the synthesis of a functionalized PBI polymer. Petition 870250090980, dated 06 / 10 / 2025, page 41 / 112 34 / 88 with boronic acid. As shown, a PBI polymer molecule is combined with a boronic acid-functionalized ligand to produce a boronic acid-functionalized PBI polymer molecule. Any boronic acid-functionalized ligand described herein may be used. It will be acknowledged that the PBI polymer molecule in Figure 1A is merely representative and the reaction scheme in Figure 1A may be carried out using any other suitable PBI polymer.

[0085] In other examples of post-polymerization functional modification, an aromatic polymer is converted into a boronic acid-functionalized polymer by borylation of an aromatic ring in the main chain, or in a side chain or side group. In some examples, the aromatic ring may be borylated directly by reaction with a borylation agent. Any suitable borylation agent may be used, including but not limited to, a boronic acid, a borate ester of general formula B(OR1)3 and / or a boronic ester of general formula R2B(OR1)2, wherein each R1 is independently an alkyl or aryl group with 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 6 carbon atoms or 1 to 4 carbon atoms, wholly or partially substituted or unsubstituted, branched or unbranched, and R2 is an alkyl, alkenyl, alkynyl or aryl group with 1 to 20 carbon atoms, 1 to 10 carbon atoms, Petition 870250090980, dated 06 / 10 / 2025, p. 42 / 112 35 / 88 to 6 carbon atoms or 1 to 4 carbon atoms, totally or partially substituted or unsubstituted, branched or unbranched. Other suitable borylation agents may be used. Illustrative examples of borylation agents include, without limitation, trialkyl borates (e.g., trimethyl borate, triethyl borate), bis(pinacolate)diboron, bis(catecholate)diborane, pinacol borate, bis(2,4-dimethylpentane-2,4-glycolate)diboron, bis(hexyleneglycolate)diboron, bis(neopentylglycolate)diboron, vinylic boronic acid and derivatives thereof. Aromatic ring borylation reactions may also include metal-catalyzed CH borylation reactions, including, but not limited to, Suzuki-Miyaura metal-catalyzed coupling reactions, which use transition metals to directly convert a CH bond into a CB bond.

[0086] Borylation of the aromatic ring produces an intermediate protected boronic acid group (e.g., —B(OR1)2). In these examples, a hydrolysis step can be performed to remove the protecting R1 groups, thus producing a pendant boronic acid group with the general formula —B(OH)2. In other examples, the hydrolysis step can be performed in situ during the borylation step (e.g., by combining the borylation agent and water in a single-vessel process). The charge of the boronic acid groups in Petition 870250090980, dated 06 / 10 / 2025, page 43 / 112 36 / 88 Polymer activity can be controlled by controlling the molar ratio of the borylation agent to the aromatic rings in the polymer. In other examples, the aromatic group (Ar) in the polymer molecule may first be converted into an active intermediate Ar-X for the subsequent borylation reaction, where X is a halo group (e.g., an iodine (I), bromine (Br), or chlorine (Cl) group) or a metal (where Ar-X is formed by a methylation reaction of the aromatic ring). In some examples, X is lithium (Li).

[0087] Figure 1B shows an illustrative reaction scheme for the synthesis of a boronic acid-functionalized PBI polymer by borylation. As shown, a PBI polymer molecule is combined with a borylation agent. The aromatic ring of the benzimidazole unit is borylated to produce a protected boronic acid intermediate group, which is then hydrolyzed to produce a pendant boronic acid group. Any suitable borylation agent can be used in place of boric acid, and the reaction scheme of Figure 1B can be carried out using any other suitable PBI polymer.

[0088] Figure 2A shows an illustrative reaction scheme for the synthesis of a boronic acid-functionalized polystyrene polymer by borylation. As shown, a polystyrene polymer molecule is combined with a borylation agent. An aromatic ring of Petition 870250090980, dated 06 / 10 / 2025, page 44 / 112 37 / 88 polystyrene repeating unit is borylated to produce a protected boronic acid group intermediate, which is then hydrolyzed to produce a pendant boronic acid group. Any suitable borylation agent can be used and the reaction scheme of Figure 2A can be carried out using any other suitable polystyrene polymer.

[0089] In further examples of post-polymerization functional modification of a polymer, a polymer with a vicinal diol in a side group or in a side chain is combined with boric acid (B(OH)3). The boric acid reacts with the vicinal hydroxyl groups to form a cyclic boronic acid group with only one hydroxyl group. Any suitable polymer with a vicinal diol can be used, including polysaccharides, cellulose, and 1,2-dihydroxyphenyl polymers.

[0090] Figure 2B shows an illustrative reaction scheme for the synthesis of a boronic acid-functionalized polymer using a vicinal diol. As shown, a polymer molecule with a pendant 1,2-dihydroxyphenyl group is combined with boric acid to produce a boronic acid-functionalized polymer with a pendant boronic acid group. In some examples, the polymer molecule includes a PTFE backbone and the ligand is an LSC, MSC, or SSC. Other configurations are also contemplated by the ligand. Although Figure 2B shows only one ligand, Petition 870250090980, dated 06 / 10 / 2025, page 45 / 112 38 / 88 The polymer molecule may have any other suitable number of side chains, linkers, and 1,2-dihydroxyphenyl groups. Furthermore, the 1,2-dihydroxyphenyl group may be part of a side chain or side group of any other polymer described herein, including, but not limited to, a PBI polymer, a sulfonic acid-functionalized polymer, a polystyrene polymer, or an aromatic polymer. In some examples, cellulose polymers and / or polysaccharides may be used to crosslink a boronic acid-functionalized polymer.

[0091] In further examples of post-polymerization functional modification of a polymer, a polymer molecule functionalized with sulfonic acid is converted into a polymer molecule functionalized with boronic acid by coupling a common boronic acid group to a pendant sulfonic acid group via a sulfonamide linkage. The reaction scheme includes several steps.

[0092] In a first step, the sulfonic acid group is activated in sulfonyl chloride (—S(=O)Cl), sulfonyl fluoride (—S(=O)F), or a sulfonic ester. For example, the polymer molecule functionalized with sulfonic acid can be combined with hydrochloric acid (HCl) or hydrofluoric acid (HF), which performs a substitution reaction to replace the hydroxyl group of the sulfonic acid group with a sulfonic acid group. Petition 870250090980, dated 06 / 10 / 2025, page 46 / 112 39 / 88 chloride, thus forming a sulfonyl chloride or sulfonyl fluoride group. Other suitable chloride and / or fluoride reagents may be used including, but not limited to, thionyl chloride, sulfuryl chloride, oxalyl chloride, thionyl fluoride and sulfuryl fluoride. A sulfonic ester has the general formula —S(=O2)OR, where R is hydrogen or an alkyl or aryl group, wholly or partially substituted or unsubstituted, with one to twenty, one to ten, one to eight, one to six or one to four carbon atoms, such as, but not limited to, a methyl, ethyl, propyl or butyl group. Examples of sulfonic ester reagents include, but not limited to, dimethyl sulfate or a dialkyl sulfate.

[0093] In a second step, a bifunctional boronic amino acid ligand is coupled to sulfonyl chloride, sulfonyl fluoride, or sulfonic ester. The bifunctional boronic amino acid ligand comprises an amino group as a terminal or side group, a boronic acid group as a terminal or side group, and an R group, where R is an alkyl chain of length m, where m ranges from 0 to 30 (or from 0 to 20, or from 0 to 12, or from 0 to 10, or from 0 to 8, or from 0 to 6) and has one or more A side groups, each of which may independently be hydrogen (H), a hydroxyl group (OH), a fluoro group (F), a chlorine group (Cl), a boronic acid group, a dialkylamino group (NR' 2, wherein Petition 870250090980, dated 06 / 10 / 2025, page 47 / 112 40 / 88 R' can represent hydrogen or an organic combining group, such as a methyl group (CH3) ), a cyano group (CN) , a carboxylic acid group (COOH), a carboxylic amide group, an ester group, an alkyl group, an alkoxy group, or an aryl group. In the second step, a primary or secondary amine in the bifunctional aminoboronic acid ligand couples orthogonally to the sulfonyl chloride, sulfonyl fluoride, or sulfonic ester, thus linking the aminoboronic acid ligand to the polymer backbone via a sulfonamide linkage. The resulting polymer molecule has a pendant boronic acid group linked to the polymer backbone (e.g., a PTFE backbone) via the ligand (e.g., via the sulfonamide linkage).

[0094] In an alternative reaction scheme, in the second step, an aromatic boronic acid of general formula ArB(OR)2 reacts with sulfonyl chloride, sulfonyl fluoride, or sulfonic ester by an electrophilic aromatic substitution reaction. In the aromatic boronic acid of general formula ArB(OR)2, each R is independently hydrogen or an alkyl or aryl group, wholly or partially substituted or unsubstituted, with one to twenty, one to ten, one to eight, one to six, or one to four carbon atoms, such as, but not limited to, a methyl, ethyl, propyl, or butyl group. Aromatic boronic acid is a protected form of boronic acid. Petition 870250090980, dated 06 / 10 / 2025, page 48 / 112 41 / 88 In this reaction scheme, the aryl group of the aromatic boronic acid couples directly to the sulfur atom of the sulfonyl chloride, sulfonyl fluoride, or sulfonic ester, forming a protected aromatic boronic acid intermediate group coupled to the polymer by a sulfonic bond. In a third step, the protecting R groups are removed to produce a free aromatic boronic acid group of general formula ArB(OH)2. For example, a hydrolysis step can be performed to remove the protecting R groups, thus producing a pendant boronic acid group with general formula —B(OH)2, coupled to the main chain via an aromatic ligand and a sulfonic bond. In other examples, the hydrolysis step can be performed in situ during the borylation step (e.g., by combining the borylation agent and water in a single-vessel process).

[0095] Figure 3A shows an illustrative reaction scheme for the synthesis of a boronic acid-functionalized polymer by coupling a boronic acid group to a pendant sulfonic acid group via a sulfonamide linkage. Any sulfonic acid-functionalized polymer molecule can be used as a starting reagent, including, but not limited to, a polyfluorosulfonic acid-functionalized PTFE polymer molecule or a sulfonic acid-functionalized PCTFE polymer molecule. In a first Petition 870250090980, dated 06 / 10 / 2025, page 49 / 112 In step 42 / 88, a pendant sulfonic acid group of the sulfonic acid-functionalized polymer molecule is activated in sulfonyl chloride, such as by combination with hydrogen chloride. However, the sulfonic acid group can be activated in sulfonyl chloride using any other chloride activating agent. Alternatively, the sulfonic acid group can be activated in sulfonyl fluoride or in a sulfonic ester. In a second step, the intermediate molecule of sulfonyl chloride-functionalized polymer is combined with an amino boronic acid ligand, which couples to the sulfonyl chloride via a sulfonamide linkage. In the example in Figure 3A, the aminoboronic acid ligand has the formula H2N(CH)2B(OH)2. However, any other aminoboronic acid ligand can be used, including any aminoboronic acid ligand described herein.

[0096] Figure 3B shows an illustrative reaction scheme for the synthesis of a boronic acid-functionalized polymer, coupling a boronic acid group to a sulfonic acid group pendant via a sulfone linkage. In the second step, a sulfonyl chloride-functionalized polymer molecule is combined with phenylboronic acid, of general formula PhB(OR)2, where each R is independently hydrogen or an alkyl or aryl group, totally or partially substituted or unsubstituted, with one to twenty, one to ten, one Petition 870250090980, dated 06 / 10 / 2025, page 50 / 112 43 / 88 to eight, one to six, or one to four carbon atoms, such as, but not limited to, a methyl, ethyl, propyl, or butyl group. Phenylboronic acid couples to sulfonyl chloride via a sulfonic bond to form a protected intermediate molecule of phenylboronic acid-functionalized polymer. In a third step, the protecting R groups are removed from the phenylboronic acid-functionalized polymer intermediate molecule, as described above, to produce a polymer molecule with a pendant phenylboronic acid group, of general formula PhB(OH)2, coupled to the polymer backbone via a sulfonic bond. In the example in Figure 3B, any other aromatic boronic acid can be used in place of phenylboronic acid. Additionally, aromatic boronic acid can be combined with sulfonyl fluoride or a sulfonic ester instead of sulfonyl chloride.

[0097] In the examples described above, a boronic acid-functionalized polymer is synthesized by post-polymerization functional modification of a polymer. In other examples, a boronic acid-functionalized polymer is synthesized by polymerization reactions using a boronic acid-functionalized monomer. For example, a monomer used to form a polymer, such as a tetrafluoroethylene (TFE) monomer, a benzimidazole monomer, a styrene polymer, or a monomer Petition 870250090980, dated 06 / 10 / 2025, page 51 / 112 44 / 88 functionalized with sulfonic acid can be modified by pre-polymerization with a boronic acid group, after which the functionalized monomer is polymerized to form a boronic acid-functionalized polymer. The monomer can be functionally modified with a boronic acid group in any way, including using any reaction scheme described in this document for the functional modification of a polymer with a boronic acid group.

[0098] In some examples, boronic acid-functionalized polymers are used to synthesize tetra-coordinated boronic acid-functionalized polymers, including fluoroboric acid-functionalized polymers. Tetra-coordinated boronic acid-functionalized polymers, as described herein, take advantage of the unique chemical bonding properties of boron. Boron has three valence electrons and a ground-state electronic configuration of 1s²2s²2p¹. Boron forms neutral, trigonal, and trivalent compounds, such as boric acid (B(OH)a), boronic acid (RB(OH)₂ or R₁R₂B(OH)), and boronic acid groups (a boronic acid in which R is part of a main or side chain of a polymer), in which boron has three covalent bonds through sp2 hybridization. The sp2 hybridized boron atom contains an empty p orbital, which makes boron compounds trivalent and strongly electron-deficient, with two fewer electrons. Petition 870250090980, dated 06 / 10 / 2025, p. 52 / 112 45 / 88 of a stable octet electronic configuration. Thus, boric acid and boronic acids are Lewis acids and readily accept an electron pair on the boron atom. The addition of an anion, such as fluoride (e.g., by treatment with fluorine) or another anion, creates the octet electronic configuration, forming highly stable, tetravalent, tetrahedral boron compounds with a negative charge and four covalent bonds. Tetravalent boron can also be called, synonymously, tetra-coordinated boron. Polymers can be functionalized with functional groups that have tetra-coordinated boron, such as tetra-coordinated boronic acid groups (e.g., fluoroboric acid groups). Functional groups, including tetra-coordinated boron, have a formal negative charge and are therefore intrinsically ionic and acidic and can function as cation transport agents in electrochemical cell applications.

[0099] Polymer molecules functionalized with tetra-coordinated boronic acid have a main chain and a tetra-coordinated boronic acid group in a side chain and / or side group. A tetra-coordinated boronic acid group has the general formula — BFmXn(OH)(3-mn), where B has four covalent bonds and is covalently linked to a main chain, side chain, or side group of the polymer; men are, each independently, 0, 1, 2, or Petition 870250090980, dated 06 / 10 / 2025, page 53 / 112 46 / 88 3; the sum of m+n is 1, 2, or 3; and X is an anion other than fluoride. In some examples, X is a conjugate base derived from a compound of the general formula HX (a Bronsted-Lowry acid) such as, but not limited to, alkylsulfonic acids of general formula RSO2(OH) where R is an alkyl group (e.g., methanesulfonic acid (CH3SO3H), vinylsulfonic acid, perfluorooctanesulfonic acid, taurine), arylsulfonic acids of general formula ArSO2(OH) where Ar is an aryl group (e.g., benzenesulfonic acid (C6H5SO3H), p-toluenesulfonic acid (C7H7SO3H)), alkylarylsulfonic acids (e.g., alkylbenzenesulfonic acids); Sulfuric acid (H2SO4) (e.g., ammonium bisulfate ((NH4)HSO4), pyridinium bisulfate, any nitrogen bisulfate heterocycle, alkylammonium bisulfates, and sulfamic acid), phosphoric acids, phosphinic acids, carboxylic acids, phenols, and derivatives of any of the foregoing.X can be derived from small molecule and polymeric Bronsted-Lowry acids. In the case of polymeric Bronsted-Lowry acids, the chemistry will bring about crosslinking, providing a wider range of applications. Tetra-coordinated boronic acid functionalized polymers encompass a wide range of polymers, including, without limitation, tetra-coordinated PTFE polymers functionalized with boronic acid, tetra-coordinated PCTFE polymers functionalized with... Petition 870250090980, dated 06 / 10 / 2025, page 54 / 112 47 / 88 boronic acid, boronic acid-functionalized tetra-coordinated polystyrene polymers, boronic acid-functionalized tetra-coordinated cellulose polymers and boronic acid-functionalized tetra-coordinated PBI polymers.

[00100] In some examples, a tetra-coordinated boronic acid-functionalized polymer molecule is synthesized by a nucleophilic substitution reaction between a pendant boronic acid group of a boronic acid-functionalized polymer molecule and a fluoride reagent (described below) and / or the compound HX (described above). The boron atom accepts a fluoride anion (F-) from the fluoride reagent and / or an X- anion from HX and, depending on the reaction stoichiometry, replaces the fluoride anion Fe- or the X- anion with one or more hydroxyl groups by a nucleophilic substitution reaction. Due to the tetra-coordinated boron atom, a tetra-coordinated boronic acid group in a tetra-coordinated boronic acid-functionalized polymer molecule has a formal negative charge and is counterbalanced by a proton.

[00101] The degree of anionic charge on the boronic acid groups, and therefore the pKa of the resulting tetra-coordinated boronic acid functionalized polymer, can be adjusted as desired based on the stoichiometry of the reagents. For example, when the molar ratio between HX and Petition 870250090980, dated 06 / 10 / 2025, page 55 / 112 48 / 88 boronic acid groups are 3 or more to 1 (>3:1), the resulting tetra-coordinated boronic acid group has the formula —BX3. Where HX is the limiting reagent, the pKa of the resulting tetra-coordinated boronic acid-functionalized polymer will be higher than where HX is not limiting. For example, where the molar ratio of HX to boronic acid groups is 2 to 1 (2:1), the resulting tetra-coordinated boronic acid group has the formula —BX2(OH). Where the molar ratio of HX to boronic acid groups is 1 to 1 (1:1), the resulting tetra-coordinated boronic acid group has the formula —BX(OH)2.

[00102] In some examples, the tetracoordinated boronic acid-functionalized polymer is a fluoroboric acid-functionalized polymer. A fluoroboric acid-functionalized polymer molecule has a polymer backbone and a fluoroboric acid group in a side chain and / or side group. A fluoroboric acid group includes a tetracoordinated boron atom covalently bonded to at least one fluorine atom and has the general formula —BFmXn(OH)(3-mn), where m is 1, 2, or 3; n is 0, 1, or 2; and the sum of m+n is 1, 2, or 3. In some examples, the fluoroboric acid group has the formula —BF3, —BF2(OH), or —BF(OH)2, and in some examples, one or two hydroxyl groups are replaced by an X- anion. Due to the tetracoordinated boron atom, a fluoroboric acid group in a Petition 870250090980, dated 06 / 10 / 2025, p. 56 / 112 49 / 88 A polymer molecule functionalized with fluoroboric acid has a formal negative charge and can be counterbalanced by a cation, such as H+, Li+, Na+, Al3+, Ni2+, or any other suitable cation, including cations used in battery applications. Polymers functionalized with fluoroboric acid include, without limitation, PTFE polymers functionalized with fluoroboric acid, PCTFE polymers functionalized with fluoroboric acid, polystyrene polymers functionalized with fluoroboric acid, cellulose polymers functionalized with fluoroboric acid, and PBI polymers functionalized with fluoroboric acid.

[00103] A PTFE polymer molecule functionalized with fluoroboric acid includes a PTFE back chain, a side group or side chain attached to the PTFE back chain, and a fluoroboric acid group on or attached to the side group or side chain. In some examples, a PTFE polymer molecule functionalized with fluoroboric acid is a derivative of a PTFE polymer molecule functionalized with sulfonic acid (for example, a PTFE polymer functionalized with polyfluorosulfonic acid, such as a Nafion™ polymer or No present documentvion®) in which one or more pendant sulfonic acid groups have been substituted for or attached to one or more fluoroboric acid groups.

[00104] A functionalized PCTFE polymer molecule Petition 870250090980, dated 06 / 10 / 2025, p. 57 / 112 50 / 88 with fluoroboric acid includes a PCTFE backbone, a side group or side chain attached to the PTFE backbone (e.g., in place of a chlorine atom), and a fluoroboric acid group on or attached to the side group or side chain. Thus, a PCTFE polymer molecule includes polymers in which one or more chlorine atoms in the PCTFE backbone have been replaced by a side chain or side group including one or more fluoroboric acid groups.

[00105] A fluoroboric acid functionalized polystyrene polymer molecule includes a polystyrene back chain and a fluoroboric acid group coupled directly to the polystyrene back chain (e.g., to a phenyl group of the polystyrene back chain) or indirectly via a linker (e.g., a side group or side chain coupled to the phenyl group). In some examples, a fluoroboric acid functionalized polystyrene polymer molecule is a derivative of a sulfonic acid functionalized polystyrene polymer molecule (e.g., a sulfonic acid polystyrene polymer (CH2CHC6H4SO3H)n) in which one or more pendant sulfonic acid groups have been substituted or to which one or more fluoroboric acid groups have been added.

[00106] A functionalized PBI polymer molecule Petition 870250090980, dated 06 / 10 / 2025, page 58 / 112 51 / 88 with fluoroboric acid includes a polybenzimidazole (PBI) backbone and a fluoroboric acid group coupled directly to the PBI backbone (e.g., to an aromatic group) or via a linker (e.g., a side group or side chain coupled to the PBI backbone). In some examples, a fluoroboric acid-functionalized PBI polymer is crosslinked with another polymer, such as another PBI polymer, a PTFE polymer, or a poly(phosphoric acid) (PPA) polymer. In some examples, the fluoroboric acid-functionalized PBI polymer comprises a PPA-doped PBI polymer (PPAPBI).

[00107] A fluoroboric acid-functionalized cellulose polymer molecule includes a cellulosic back chain, a side group or side chain attached to the back chain, and a fluoroboric acid group on or attached to the side group or side chain. In some examples, a fluoroboric acid-functionalized cellulose polymer molecule is a derivative of a sulfonic acid-functionalized cellulose polymer molecule or a boronic acid-functionalized cellulose polymer molecule, in which one or more pendant sulfonic acid groups or boronic acid groups have been replaced by a side chain or side group including one or more fluoroboric acid groups. Petition 870250090980, dated 06 / 10 / 2025, page 59 / 112 52 / 88

[00108] In some examples, a fluoroboric acid-functionalized polymer molecule is synthesized by performing a fluorine treatment on a boronic acid-functionalized polymer molecule. Any boronic acid-functionalized polymer molecule described herein may be used. The fluorine treatment functionalizes the boronic acid-functionalized polymer molecule at the boronic acid group with a fluoroboric acid group with a tetra-coordinated boron atom. The fluorine treatment may be performed in any suitable manner.

[00109] In some examples, the fluoride treatment comprises combining a boronic acid-functionalized polymer molecule with a fluoride reagent. In some examples, the reagent compound comprises hydrogen fluoride (HF), lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF), potassium bifluoride (KHF2), cesium fluoride (CsF), ammonium fluoride (NH4F), ammonium bifluoride (NH4F2), or a tetraalkylammonium fluoride (having the general formula NR4F, wherein each R is independently hydrogen or an alkyl or aryl group wholly or partially substituted or unsubstituted with one to twenty, one to ten, one to eight, one to six, or one to four carbon atoms, such as, but not limited to, a methyl, ethyl, propyl, or butyl group). In some examples, the treatment Petition 870250090980, dated 06 / 10 / 2025, pages 60 / 112 Fluoride treatment (53 / 88) is carried out with two or more different fluoride reagents (e.g., HF and NaF, HF and LiF, etc.). Fluoride treatment adds a fluoride group to a pendant boronic acid group to form a fluoroboric acid group, in which the boron atom is tetra-coordinated and covalently bonded to the fluoride group. Depending on the stoichiometry of the reaction, fluoride treatment may also replace one or more hydroxyl groups of the pendant boronic acid group with a fluoride group.

[00110] The fluoride compound combines with a boronic acid group of the boronic acid-functionalized polymer molecule to form a pendant fluoroboric acid group. One or more hydroxyl groups of the boronic acid group are replaced by fluoride from the fluoride compound, and a fourth fluoride group is added. Thus, the boron atom becomes tetra-coordinated, so that the pendant fluoroboric acid group has a formal negative charge and is counterbalanced by a cation (e.g., H+, Li+, Na+, K+, Cs+, NH4+, or NR4+).

[00111] In some examples where the countercation is not hydrogen (for example, when the fluoride compound is one or more of LiF, NaF, KF, KHF2, CsF, NH4F, NH4F2, or NR4F), the fluoride treatment may be followed by a protonation step to replace the countercation with a proton (H+). The protonation step can be carried out in Petition 870250090980, dated 06 / 10 / 2025, pp. 61 / 112 54 / 88 any suitable method. In some examples, the protonation step is performed by combining the fluoroboric acid-functionalized polymer molecule with a strong acid. Examples of suitable strong acids include, but are not limited to, hydrochloric acid (HCl), sulfuric acid (H2SO4), methanesulfonic acid (CH3SO3H), and trifluoroacetic acid (CF3CO2H). After the protonation step, the pendant fluoroboric acid group is counterbalanced by a proton (H+).

[00112] In other examples of fluoride treatment, the hydrogen atom of one or more hydroxyl groups of the pendant boronic acid group is replaced by a fluoroboric acid group. In these examples, the fluoride treatment comprises combining the boronic acid-functionalized polymer molecule with a fluoroboric compound of formula BFm(OH)(3-m), where m is 1, 2, or 3 (e.g., fluorodihydroxyboric acid (BF(OH)2), difluorohydroxyboric acid (BF2(OH)), and / or boron trifluoride (BF3)). In other examples, the fluoride treatment may also include combining the boronic acid-functionalized polymer molecule with a boronic acid RB(OH)2 and fluoride reagent (e.g., HF) in situ in a single-vessel process, with the fluoride reagent as the limiting reagent, where R is an alkyl or aryl group (e.g., 1 to 20, 1 to 10, 1 to 8, 1 to 6, 1 to 4, or 1 to 3 carbon atoms), branched or unbranched, wholly or partially Petition 870250090980, dated 06 / 10 / 2025, pp. 62 / 112 55 / 88 replaced or not replaced.

[00113] In examples where the reaction results in a tetra-coordinated boronic acid group with one or two remaining hydroxyl groups, the same reaction can be repeated or a different reaction can be performed to replace one or both remaining hydroxyl groups with a fluoride group or an anionic group X-, in the manner described above. In other examples, the conversion of a boronic acid group into a tetra-coordinated boronic acid group can be performed using multiple reagents in the same step (e.g., at least two of the compound XH, a fluoride reagent, a fluoroboronic compound, or a boronic acid).

[00114] Illustrative reaction schemes for synthesizing a fluoroboric acid functionalized polymer using a boronic acid functionalized polymer as starting material will be described below.

[00115] Figures 4A-4C show illustrative reaction schemes for synthesizing a fluoroboric acid functionalized polymer by performing a fluoride treatment of a boronic acid. Any boronic acid functionalized polymer described in this document may be used, including but not limited to a boronic acid functionalized PBI polymer, a boronic acid functionalized PTFE polymer, or a boronic acid functionalized polystyrene polymer. Petition 870250090980, dated 06 / 10 / 2025, pp. 63 / 112 56 / 88

[00116] In the example in Figure 4A, the fluoride treatment comprises combining the boronic acid-functionalized polymer molecule with hydrogen fluoride or sodium fluoride as the fluoride reagent. The fluoride groups of the fluoride reagent replace the hydroxyl groups of the boronic acid group. The resulting product is a fluoroboric acid-functionalized polymer molecule with a pendant fluoroboric acid group. The fluoroboric acid group has a tetra-coordinated boron atom covalently bonded to the main chain or to a side chain or side group and to three fluorine atoms. Thus, the fluoroboric acid group has a formal negative charge and is intrinsically ionic and acidic, being counterbalanced by a cation derived from the fluoride reagent. Where the fluoride reagent is HF, the cation is a proton.When the fluoride reagent is NaF (or any other fluoride reagent), a protonation step is performed after fluoride treatment to replace the countercation with a proton. However, in some examples, the protonation step is omitted so that the fluoroboric acid group is counterbalanced by the cation derived from the fluoride reagent.

[00117] The degree of fluorine charge on the boronic acid groups and on the boronic acid-functionalized polymer molecule, and therefore the pKa of the resulting fluoroboric acid-functionalized polymer, can be adjusted in the manner Petition 870250090980, dated 06 / 10 / 2025, pp. 64 / 112 57 / 88 desired based on the stoichiometry of the reagents. Fluorine is the most electronegative element and therefore the acidity of fluoroboric acid increases with the increase in the number of fluorine atoms covalently bonded to the boron atom. As shown in the example in Figure 4A, the molar ratio of the fluoride reagent to the boronic acid groups is three or more to one (> 3:1), resulting in a trifluoroboric acid group. The presence of three fluorine atoms covalently bonded to the tetra-coordinated boron atom in the resulting polymer structure makes trifluoroboric acid the most acidic fluoroboric acid (the lowest pKa). Thus, by the reaction scheme in Figure 4A, the boronic acid-functionalized polymer can be converted into a fluoroboric acid-functionalized polymer, a superacidic and strongly proton-conducting polymer that is intrinsically ionic with tetra-coordinated anionic boron atoms.

[00118] The versatile chemistry of the fluoride treatment process allows the synthesis of fluoroboric acid groups that are less acidic than the trifluoroboric acid group in Figure 4A. For example, the molar ratio between the fluoride reagent (e.g., HF) and the boronic acid group can be less than 3:1, so that the fluoride reagent is the limiting reagent. The pKa of the resulting fluoroboric acids will be higher (less acidic) than the superacidic trifluoroboric acid. Petition 870250090980, dated 06 / 10 / 2025, pp. 65 / 112 58 / 88 and smaller (more acidic) than the weakly acidic boronic acid group of the initial boronic acid-functionalized polymer molecule. The pKa can be controlled to a desired level for many applications, including electrochemical processes for ammonia production. For example, when the molar ratio between the fluoride reagent and the boronic acid group is approximately 1:1, one fluorine atom covalently bonds to the boron atom, as shown in the reaction scheme in Figure 4B. When the molar ratio between the fluoride reagent and the boronic acid group is approximately 2:2, two fluorine atoms covalently bond to the boron atom, as shown in the reaction scheme in Figure 4C. Any suitable molar ratio between the fluoride reagent and the boronic acid group can be used, such as 3:1 or higher, 2.5:1, 2:1, 1.5:1, 1:1, 0.5:1, or any other suitable ratio.

[00119] Figures 5A and 5B show alternative illustrative reaction schemes for synthesizing a fluoroboric acid functionalized polymer by performing a fluorine treatment of a boronic acid functionalized polymer. Any boronic acid functionalized polymer described herein may be used, including but not limited to a boronic acid functionalized PBI polymer, a boronic acid functionalized PTFE polymer, or a boronic acid functionalized polystyrene polymer. Petition 870250090980, dated 06 / 10 / 2025, pp. 66 / 112 59 / 88 boronic acid.

[00120] In the example in Figure 5A, the fluorine treatment comprises combining the boronic acid-functionalized polymer molecule with boron trifluoride (BF3) to produce a proton-superconducting dibasic fluoroboric acid-functionalized polymer molecule. Boron trifluoride can be used in its diethyl ether and / or tetrahydrofuran complexes. A fluoroboric acid group replaces one hydrogen atom of both hydroxyl groups of the boronic acid group. The presence of three fluorine atoms covalently bonded to the tetra-coordinated boron atom in the resulting polymer structure makes it a superacidic fluoroboric acid. Thus, the boronic acid group is converted into a proton-superconducting dibasic acid using boron trifluoride. The dibasic acid exhibits twice the ion exchange capacity (IEC) compared to monobasic acids. A higher IEC increases proton conductivity, thus increasing the efficiency of an ionomer and a PEM.The additional fluorine atoms also help modulate the hydrophobic-hydrophilic balance and hydrogen bonding networks in polymers, further facilitating proton transport.

[00121] The degree of fluorine charge on the boronic acid group and on the boronic acid-functionalized polymer, and therefore the pKa of the boronic acid-functionalized polymer. Petition 870250090980, dated 06 / 10 / 2025, pp. 67 / 112 The resulting 60 / 88 fluoroboric polymer can be adjusted as desired based on the stoichiometry of the reagents. As shown in the example in Figure 5A, the molar ratio between the boron trifluoride and boronic acid groups is two or more to one (> 2:1). The presence of three fluorine atoms covalently bonded to the tetravalent boron atom in the resulting polymer structure makes it the most acidic fluoroboric acid (the lowest pKa). Thus, according to the reaction scheme in Figure 5A, the boronic acid-functionalized polymer can be converted into a superacidic, strongly proton-conducting, intrinsically ionic fluoroboric acid-functionalized polymer with tetra-coordinated anionic boron atoms.

[00122] The versatile chemistry of fluorine treatment allows the synthesis of a fluoroboric acid-functionalized polymer that is less acidic than the trifluoroboric acid-functionalized polymer in Figure 5A. For example, the molar ratio between boron trifluoride and boronic acid groups can be less than 2:1, so that boron trifluoride is the limiting reagent, resulting in a product with an intermediate pKa. When the molar ratio between boron trifluoride and boronic acid groups is approximately 1:1, only one hydrogen atom of a boronic acid group is replaced by a fluoroboric acid group, as shown in Figure 5B. The pKa can be controlled down to a level Petition 870250090980, dated 06 / 10 / 2025, pp. 68 / 112 61 / 88 desired using any suitable molar ratio between the boron trifluoride and boronic acid groups, such as 2:1 or greater, 1.5:1, 1:1, 0.5:1 or any other suitable ratio.

[00123] Figures 6 and 7 show illustrative reaction schemes for the synthesis of a fluoroboric acid-functionalized PBI polymer, performing a fluorine treatment on a boronic acid-functionalized PBI polymer. In the example in Figure 6, the fluorine treatment comprises combining the boronic acid-functionalized polymer molecule with hydrogen fluoride or sodium fluoride as the fluoride reagent. The fluoride groups of the fluoride reagent replace the hydroxyl groups of the boronic acid group. The resulting product is a fluoroboric acid-functionalized polymer molecule with a pendant trifluoroboric acid group. The trifluoroboric acid group has a tetra-coordinated boron atom covalently bonded to a side chain and three fluorine atoms. Thus, the fluoroboric acid group has a formal negative charge and is intrinsically ionic and acidic, being counterbalanced by a cation.

[00124] The degree of fluorine charge in the boronic acid groups and in the boronic acid-functionalized PBI polymer, and therefore the pKa of the resulting fluoroboric acid-functionalized PBI polymer, can be adjusted as desired based on the stoichiometry of the reagents. In the manner Petition 870250090980, dated 06 / 10 / 2025, pp. 69 / 112 62 / 88 as shown in the example in Figure 6, the molar ratio of HF or NaF to boronic acid groups is equal to or greater than about 6:1, either in one step or in multiple steps, resulting in one trifluoroboric acid group in place of each boronic acid group.

[00125] In other examples, HF is the limiting reagent, so the pKa of the resulting fluoroboric acids will be higher (less acidic) than the superacidic trifluoroboric acid of Figure 6 and lower (more acidic) than the weakly acidic boronic acid group of the PBI polymer functionalized with initial boronic acid. For example, when the molar ratio between the fluoride reagent and the boronic acid groups is approximately 2:1, one fluorine atom covalently bonds to each boron atom of the boronic acid groups attached to the PBI repeating unit, as shown in the reaction scheme of Figure 7. When the molar ratio between the fluoride reagent and the boronic acid groups is approximately 4:2, or when another stage of fluorine treatment is carried out, another fluorine atom covalently bonds to each boron atom.Any suitable molar ratio between the fluoride reagent and the boronic acid groups may be used, such as 6:1 or higher, 5:1, 4:1, 3:1, 2:1, 1:1, or any other suitable ratio.

[00126] Figures 8 and 9 show alternative illustrative reaction schemes for synthesizing a PBI polymer. Petition 870250090980, dated 06 / 10 / 2025, pp. 70 / 112 63 / 88 functionalized with fluoroboric acid, performing a fluorine treatment of a boronic acid-functionalized PBI polymer. The reaction scheme in Figure 8 is similar to the reaction schemes in Figures 6 and 7, except that in the reaction scheme in Figure 8, the boronic acid group is directly bonded to an aromatic group in the PBI repeating unit. In the example in Figure 8, the fluorine treatment comprises combining the boronic acid-functionalized polymer molecule with hydrogen fluoride or sodium fluoride as a fluorine reagent (followed by protonation with HCl). The fluoride groups of the fluorine reagent replace the hydroxyl groups of the boronic acid group. The resulting product is a fluoroboric acid-functionalized polymer molecule with a pendant trifluoroboric acid group. The trifluoroboric acid group has a tetra-coordinated boron atom covalently bonded to a side chain and three fluorine atoms.Thus, the fluoroboric acid group has a formal negative charge and is intrinsically ionic and acidic, being counterbalanced by a cation.

[00127] The degree of fluorine charge in the boronic acid groups and in the boronic acid-functionalized PBI polymer, and therefore the pKa of the resulting fluoroboric acid-functionalized PBI polymer, can be adjusted as desired based on the stoichiometry of the reagents. In the manner Petition 870250090980, dated 06 / 10 / 2025, pp. 71 / 112 64 / 88 as shown in the example in Figure 8, the molar ratio of HF or NaF to boronic acid groups is equal to or greater than approximately 3:1, resulting in a trifluoroboric acid group.

[00128] In other examples, the fluoride reagent is the limiting reagent, so the pKa of the resulting fluoroboric acids will be higher (less acidic) than the superacidic trifluoroboric acid of Figure 8 and lower (more acidic) than the weakly acidic boronic acid group of the starting boronic acid-functionalized PBI polymer. For example, when the molar ratio between the fluoride reagent and the boronic acid groups is approximately 1:1, a fluorine atom covalently bonds to the boron atom of the boronic acid group, as shown in the reaction scheme of Figure 9. When the molar ratio between the fluoride reagent and the boronic acid groups is approximately 2:2, or when another stage of fluorine treatment is carried out, another fluorine atom covalently bonds to the boron atom.Any suitable molar ratio between the fluoride reagent and the boronic acid groups may be used, such as 3:1 or higher, 2.5:1, 2:1, 1.5:1, 1:1, 0.5:1, or any other suitable ratio.

[00129] Figures 10A and 10B show illustrative reaction schemes for the synthesis of a fluoroboric acid-functionalized polystyrene polymer, performing a fluoride treatment of a polymer of Petition 870250090980, dated 06 / 10 / 2025, pp. 72 / 112 65 / 88 Boronic acid-functionalized polystyrene. In the example in Figure 10A, the fluoride treatment comprises combining the boronic acid-functionalized polystyrene polymer molecule with hydrogen fluoride or sodium fluoride as a fluoride reagent. The fluoride groups of the fluoride reagent replace the hydroxyl groups of the boronic acid group. The resulting product is a fluoroboric acid-functionalized polymer molecule with a pendant trifluoroboric acid group. The trifluoroboric acid group has a tetra-coordinated boron atom covalently bonded to a side chain and three fluorine atoms. Thus, the fluoroboric acid group has a formal negative charge and is intrinsically ionic and acidic, being counterbalanced by a cation.

[00130] The degree of fluorine charge on boronic acid groups and on the boronic acid-functionalized polystyrene polymer, and therefore the pKa of the resulting fluoroboric acid-functionalized polystyrene polymer, can be adjusted as desired based on the stoichiometry of the reagents. As shown in the example in Figure 10A, the molar ratio of HF or NaF to boronic acid groups is equal to or greater than about 3:1, resulting in a trifluoroboric acid group.

[00131] In other examples, the fluoride reagent is the limiting reagent, so the pKa of the acids Petition 870250090980, dated 06 / 10 / 2025, pp. 73 / 112 The resulting 66 / 88 fluoroboric acid will be larger (less acidic) than the superacidic trifluoroboric acid of Figure 10A and smaller (more acidic) than the weakly acidic boronic acid group of the starting boronic acid-functionalized polystyrene polymer. For example, when the molar ratio between the fluoride reagent and the boronic acid groups is approximately 1:1, a fluorine atom covalently bonds to the boron atom of the boronic acid group, as shown in the reaction scheme of Figure 10B. When the molar ratio between the fluoride reagent and the boronic acid groups is approximately 2:2, or when another stage of fluorine treatment is carried out, another fluorine atom covalently bonds to the boron atom. Any suitable molar ratio between the fluoride reagent and the boronic acid groups may be used, such as 3:1 or higher, 2.5:1, 2:1, 1.5:1, 1:1, 0.5:1, or any other suitable ratio.

[00132] Figures 11A and 11B show illustrative reaction schemes for the synthesis of a fluoroboric acid-functionalized polymer by performing a fluoride treatment of a boronic acid-functionalized polymer. In the example in Figure 11A, the fluoride treatment comprises combining a boronic acid-functionalized polymer molecule with hydrogen fluoride or sodium fluoride as the fluoride reagent. The boronic acid-functionalized polymer molecule is a derivative of Petition 870250090980, dated 06 / 10 / 2025, pp. 74 / 112 67 / 88 A sulfonic acid-functionalized polymer molecule, which has a boronic acid group in place of a sulfonic acid group. The boronic acid group is linked to a main chain by a ligand through a sulfonamide linkage. The fluoride groups of the fluoride reagent replace the hydroxyl groups of the boronic acid group. The resulting product is a fluoroboric acid-functionalized polymer molecule, possessing a pendant trifluoroboric acid group, linked to the main chain by a ligand through a sulfonamide linkage. The trifluoroboric acid group has a tetra-coordinated boron atom covalently bonded to a side chain and three fluorine atoms. Thus, the fluoroboric acid group has a formal negative charge, is intrinsically ionic and acidic, and is counterbalanced by a cation.

[00133] The degree of fluorine charge on the boronic acid groups and on the boronic acid-functionalized polymer, and therefore the pKa of the resulting fluoroboric acid-functionalized polymer, can be adjusted as desired based on the stoichiometry of the reagents. As shown in the example in Figure 11A, the molar ratio of HF or NaF to boronic acid groups is equal to or greater than about 3:1, resulting in a trifluoroboric acid group.

[00134] In other examples, the fluoride reagent is the limiting reagent, so the pKa of the acids Petition 870250090980, dated 06 / 10 / 2025, pp. 75 / 112 The resulting 68 / 88 fluoroboric acid will be larger (less acidic) than the superacidic trifluoroboric acid of Figure 11A and smaller (more acidic) than the weakly acidic boronic acid group of the starting boronic acid-functionalized polystyrene polymer. For example, when the molar ratio between the fluoride reagent and the boronic acid groups is approximately 1:1, a fluorine atom covalently bonds to the boron atom of the boronic acid group, as shown in the reaction scheme of Figure 11B. When the molar ratio between the fluoride reagent and the boronic acid groups is approximately 2:2, or when another stage of fluorine treatment is carried out, as shown in Figure 11B, another fluorine atom covalently bonds to the boron atom. Any suitable molar ratio between the fluoride reagent and the boronic acid groups may be used, such as 3:1 or higher, 2.5:1, 2:1, 1.5:1, 1:1, 0.5:1, or any other suitable ratio.

[00135] Figures 12 and 13 show alternative illustrative reaction schemes for synthesizing a fluoroboric acid-functionalized polymer by performing a fluoride treatment of a boronic acid-functionalized polymer. In the example in Figure 12, the boronic acid-functionalized polymer is a derivative of a sulfonic acid-functionalized polymer, having a boronic acid group attached to the main chain by a ligand. Petition 870250090980, dated 06 / 10 / 2025, pp. 76 / 112 69 / 88 via a sulfonamide linkage. However, any other boronic acid-functionalized polymer may be used, including but not limited to boronic acid-functionalized PBI polymer, boronic acid-functionalized PTFE polymer, boronic acid-functionalized PCTFE polymer, or boronic acid-functionalized polystyrene polymer.

[00136] In the example in Figure 12, the fluorine treatment comprises combining the boronic acid-functionalized polymer molecule with boron trifluoride (BF3) to produce a proton-superconducting dibasic fluoroboric acid-functionalized polymer molecule. Boron trifluoride can be used in its diethyl ether and / or tetrahydrofuran complexes. A trifluoroboric acid group replaces one hydrogen atom of both hydroxyl groups of the boronic acid group. The presence of three fluorine atoms covalently bonded to the tetra-coordinated boron atom in the resulting polymer structure makes it a superacidic fluoroboric acid. Thus, the boronic acid group is converted into a proton-superconducting dibasic acid using boron trifluoride. The dibasic acid exhibits twice the ion exchange capacity compared to monobasic acids.

[00137] The degree of fluorine charge in the boronic acid groups and in the boronic acid-functionalized polymer, and, Petition 870250090980, dated 06 / 10 / 2025, pp. 77 / 112 70 / 88 therefore, the pKa of the resulting fluoroboric acid functionalized polymer can be adjusted as desired based on the stoichiometry of the reagents. As shown in the example in Figure 12, the molar ratio of BF3 to boronic acid groups is equal to or greater than approximately 2:1, resulting in two trifluoroboric acid groups.

[00138] In other examples, BF3 is the limiting reagent, so the pKa of the resulting fluoroboric acids will be higher (less acidic) than the superacidic trifluoroboric acid of Figure 12 and lower (more acidic) than the weakly acidic boronic acid group of the starting boronic acid-functionalized polystyrene polymer. For example, when the molar ratio of BF3 to boronic acid groups is approximately 1:1, a trifluoroboric group covalently bonds to an oxygen atom of the boronic acid group, as shown in the reaction scheme of Figure 13. When the molar ratio of BF3 to boronic acid groups is approximately 2:2, or another stage of fluoride treatment is carried out, as shown in Figure 13, another trifluoroboric acid group covalently bonds to the other oxygen atom of the boronic acid group.Any suitable molar ratio of BF3 to boronic acid groups may be used, such as 2:1 or higher, 1.5:1, 1:1, 0.5:1, or any other suitable ratio.

[00139] Figure 14 shows another reaction scheme. Petition 870250090980, dated 06 / 10 / 2025, pp. 78 / 112 Figure 71 / 88 illustrates the synthesis of a fluoroboric acid-functionalized polymer. As shown, the boronic acid-functionalized polymer is a derivative of a sulfonic acid-functionalized polymer. However, any other boronic acid-functionalized polymer may be used, including but not limited to a boronic acid-functionalized PBI polymer, a boronic acid-functionalized PTFE polymer, or a boronic acid-functionalized polystyrene polymer.

[00140] In the example in Figure 14, the boronic acid-functionalized polymer molecule is combined with a fluoroboric acid (BF(OH)2) to produce a fluoroboric acid-functionalized polymer molecule. A fluoroboric acid group replaces a hydrogen atom of one or both hydroxyl groups of the boronic acid group, depending on the stoichiometry of the reaction. The presence of the fluorine atom covalently bonded to the tetra-coordinated boron atom in the resulting polymer structure results in an acidic fluoroboric acid group. Thus, the boronic acid group of the initial polymer molecule is converted into a proton-conducting fluoroboric acid group using a fluoroboric acid reagent. In other examples, the fluoroboric acid reagent has the formula BF2(OH) or RBF(OH), where R is an alkyl or aryl group.

[00141] The degree of fluorine charge in the polymer Petition 870250090980, dated 06 / 10 / 2025, pp. 79 / 112 72 / 88 functionalized with boronic acid, and therefore the pKa of the resulting fluoroboric acid-functionalized polymer can be adjusted as desired based on the type and stoichiometry of the reagents.

[00142] The tetra-coordinated boronic acid functionalized polymers described herein, including fluoroboric acid functionalized polymers, can be used in proton exchange membranes and ionomers for water electrolysis and fuel cell applications.

[00143] Figure 15 shows an illustrative water electrolysis system with a 1500 proton exchange membrane (PEM 1500 water electrolysis system) incorporating tetra-coordinated PEMs and / or boronic acid-functionalized polymer ionomers. The PEM 1500 water electrolysis system uses electricity to split water into oxygen (O2) and hydrogen (H2) through an electrochemical reaction. The configuration of the PEM 1500 water electrolysis system is merely illustrative and not limiting, since other suitable configurations, as well as other suitable water electrolysis systems, may incorporate tetra-coordinated boronic acid functionalized polymers.

[00144] As shown in Figure 15, the PEM 1500 water electrolysis system includes a set of membrane electrodes 1502 (MEA 1502), transport layers Petition 870250090980, dated 06 / 10 / 2025, pages 80 / 112 73 / 88 porous plates 1504-1 and 1504-2 (e.g., gas diffusion layers), bipolar plates 1506-1 and 1506-2, and an electrical power supply 1508. The PEM 1500 water electrolysis system may also include additional or alternative components not shown in Figure 15, which may function as a specific implementation.

[00145] MEA 1502 includes a PEM 1510 positioned between a first catalyst layer 1512-1 and a second catalyst layer 1512-2. PEM 1510 electrically isolates the first catalyst layer 1512-1 from the second catalyst layer 1512-2, providing selective conductivity of cations such as protons (H+), and being impermeable to gases such as hydrogen and oxygen. PEM 1510 can be implemented by a tetra-coordinated polymer functionalized with boronic acid (for example, a polymer functionalized with fluoroboric acid), as described in this document, or by any other suitable polymer.

[00146] The first catalyst layer 1512-1 and the second catalyst layer 1512-2 are electrically conductive electrodes that include solid catalyst supports bonded with electrocatalyst particles (not shown), such as platinum group metals, metal alloys and / or metal oxides. The first catalyst layer 1512-1 and the second catalyst layer 1512-2 may also include one or more ionomers mixed with the Petition 870250090980, dated 06 / 10 / 2025, pp. 81 / 112 74 / 88 Solid catalyst supports and electrochemical catalyst particles. The ionomers can be implemented by a tetra-coordinated polymer functionalized with boronic acid (e.g., a polymer functionalized with fluoroboric acid), in the manner described herein, or by any other suitable ionomer.

[00147] MEA 1502 is positioned between the porous transport layers 1504-1 and 1504-2, which in turn are positioned between the bipolar plates 1506-1 and 1506-2, with the flow channels 1514-1 and 1514-2 located between the bipolar plates 1506 and the porous transport layers 1504.

[00148] In MEA 1502, the first catalyst layer 1512-1 functions as an anode and the second catalyst layer 1512-2 functions as a cathode. When the PEM 1500 water electrolysis system is powered by the power supply 1508, an oxygen evolution reaction (OER) occurs in the first layer / anode of catalyst 1512-1, facilitated by the electrocatalysts attached to the solid catalyst supports in the first layer / anode of catalyst 1512-1. The OER is represented by the following electrochemical half-reaction: H2O ^ O2 + 4 H++ 4 e

[00149] Protons are conducted from the first catalyst / anode layer 1512-1 to the second layer of Petition 870250090980, dated 06 / 10 / 2025, pp. 82 / 112 75 / 88 catalyst / cathode 1512-2 through PEM 1510, and electrons are conducted from the first layer of catalyst / anode 15121 to the second layer of catalyst / cathode 1512-2 through a conductive pathway around PEM 1510. PEM 1510 allows the transport of protons (H+) and water from the first layer of catalyst / anode 1512-1 to the second layer of catalyst / cathode 1512-2, but is impermeable to oxygen and hydrogen. In the second layer of catalyst / cathode 1512-2, protons combine with electrons in a hydrogen evolution reaction (HER), facilitated by electrocatalysts attached to the solid catalyst supports in the second layer of catalyst / anode 1512-2. HER is represented by the following electrochemical half-reaction: H+ + 4 e-^ 2 H2

[00150] OER and HER are two complementary electrochemical reactions for the separation of water by electrolysis, represented by the following general water electrolysis reaction: H2O ^ 2 H2 + O2

[00151] Figure 16 shows an illustrative 1600 proton exchange membrane fuel cell (PEM 1600 fuel cell) including tetracoordinated boronic acid-functionalized PEMs and / or polymeric ionomers (e.g., PEMs and / or polymeric ionomers). Petition 870250090980, dated 06 / 10 / 2025, pp. 83 / 112 76 / 88 functionalized with fluoroboric acid). The PEM 1600 fuel cell produces electricity as a result of electrochemical reactions. In this example, the electrochemical reactions involve the reaction of hydrogen gas (H2) and oxygen gas (O2) to produce water and electricity. The configuration of the PEM 1600 fuel cell is merely illustrative and not limiting.

[00152] As shown in Figure 16, the PEM 1600 fuel cell includes a membrane electrode array 1602 (MEA 1602), porous transport layers 16041 and 1604-2 (e.g., gas diffusion layers), and bipolar plates 1606-1 and 1606-2. An electrical load 1608 can be electrically connected to the MEA 1602 and driven by the PEM 1600 fuel cell. The PEM 1600 fuel cell may also include additional or alternative components not shown in Figure 16, as may be appropriate for a specific implementation.

[00153] MEA 1602 includes a PEM 1610 positioned between a first catalyst layer 1612-1 and a second catalyst layer 1612-2. The PEM 1610 electrically isolates the first catalyst layer 1612-1 from the second catalyst layer 1612-2, while providing selective conductivity of cations such as protons (H+) and is impermeable to gases such as hydrogen and oxygen. The PEM 1610 can be implemented by any appropriate PEM in this document. Petition 870250090980, dated 06 / 10 / 2025, pp. 84 / 112 77 / 88 described.

[00154] The first catalyst layer 1612-1 and the second catalyst layer 1612-2 are electrically conductive electrodes that include solid catalyst supports that bind electrocatalyst particles (not shown), such as platinum metals, metal alloys and / or metal oxides. The first catalyst layer 1612-1 and the second catalyst layer 1612-2 may also include one or more ionomers mixed with the solid catalyst supports and electrochemical catalyst particles. The ionomers may be implemented by any suitable polymers or ionomers described herein, including any tetra-coordinated boronic acid functionalized polymers described herein, or by any other suitable ionomers.

[00155] MEA 1602 is positioned between the porous transport layers 1604-1 and 1604-2, which in turn are positioned between the bipolar plates 1606-1 and 1606-2, with flow channels 1614 located between them. In MEA 1602, the first catalyst layer 1612-1 functions as a cathode and the second catalyst layer 1612-2 functions as an anode. The first catalyst / cathode layer 1612-1 and the anode 1612-2 are electrically connected to the load 1608, and the electricity generated by the PEM fuel cell 1600 drives the load 1608. Petition 870250090980, dated 06 / 10 / 2025, pages 85 / 112 78 / 88

[00156] During the operation of the PEM 1600 fuel cell, hydrogen gas (H2) flows to the anode side of the PEM 1600 fuel cell and oxygen gas (O2) flows to the cathode side of the PEM 1600 fuel cell. In the second catalyst / anode layer 1612-2, hydrogen molecules are catalytically split into protons (H+) and electrons (e-) according to the following hydrogen oxidation reaction (HOR), which is facilitated by the electrocatalyst particles attached to the solid catalyst supports in the second catalyst / anode layer 1612-2: 2 H2 ^ 4 H+ + 4 e

[00157] Protons are conducted from the anode 1612-2 to the first catalyst / cathode layer 1612-1 through the PEM 1600, and electrons are conducted from the second layer of catalyst / anode 1612-2 for the first layer of catalyst / cathode 1612-1 around the PEM 1610 through a conductive path and load 1608.In the first catalyst / cathode layer 1612-1, protons and electrons combine with oxygen gas according to the following oxygen reduction reaction (ORR), which is facilitated by the electrochemical catalyst particles attached to the solid catalyst supports in the first catalyst / anode layer 1612-1. O2 + 4 H++ 4 e- ^ 2 H2O

[00158] Thus, the general electrochemical reaction for the Petition 870250090980, dated 06 / 10 / 2025, pages 86 / 112 The 79 / 88 PEM 1600 fuel cell is: H2 + O2 ^ 2 H2O

[00159] In the overall reaction, the PEM 1600 fuel cell produces water in the first catalyst / cathode layer 1612-1. Water can flow from the first catalyst / cathode layer 1612-1 to the second catalyst / anode layer 1612-2 through the PEM 1610 and can be removed through outlets on the cathode and / or anode side of the PEM 1600 fuel cell. The overall reaction generates electrons at the anode that drive the charge 1608.

[00160] In the examples in Figures 14 and 15, MEA 1502 and MEA 1602 include the 1512 / 412 catalyst layers formed on PEM 1510 / 410. In alternative configurations, the 1512 / 412 catalyst layers can be coated onto PEM 110 / 410 to form a catalyst-coated membrane (CCM). For example, the 1512 / 212 catalyst layers can be formed in a single-vessel or step-by-step process and sprayed onto PEM 1510 / 410.

[00161] Several examples and embodiments have been described and illustrated in this document. However, it will be evident that various modifications and alterations can be made, and additional embodiments can be implemented, without departing from the scope of the following claims. For example, certain features of an embodiment described in this document may be Petition 870250090980, dated 06 / 10 / 2025, p. 87 / 112 80 / 88 combined with or replaced by features of another embodiment described in this document. The description and drawings should therefore be considered in an illustrative and not restrictive sense.

[00162] The advantages and features of the present description can be further described by the following examples: Example 1. A method for creating a boronic acid-functionalized tetra-coordinated polymer molecule, comprising: reacting a pendant boronic acid group of a boronic acid-functionalized polymer molecule with a fluoride reagent and / or a compound having the general formula HX, wherein HX is a Bronsted-Lowry acid.

[00163] Example 2. The method of example 1, wherein the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized polybenzimidazole (PBI) polymer molecule.

[00164] Example 3. The method of example 1, wherein the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized aromatic polymer molecule.

[00165] Example 4. The method of example 1, wherein the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized PTFE polymer molecule. Petition 870250090980, dated 06 / 10 / 2025, pp. 88 / 112 81 / 88

[00166] Example 5. The method of example 1, wherein the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized PCTFE polymer molecule.

[00167] Example 6. The method of example 1, wherein the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized cellulose polymer molecule.

[00168] Example 7. The method of any of the preceding examples, wherein: the method comprises reacting the pendant boronic acid group with the fluoride reagent; and the fluoride reagent comprises hydrogen fluoride (HF), lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF), potassium bifluoride (KHF2), cesium fluoride (CsF), ammonium fluoride (NH4F), ammonium bifluoride (NH4F2), or a tetraalkylammonium fluoride with the general formula NR4F, wherein each R is independently hydrogen or a substituted or unsubstituted alkyl or aryl group.

[00169] Example 8. The method of example 7, wherein: the method comprises reacting the pendant boronic acid group with the fluoride reagent; and the fluoride reagent comprises boron trifluoride.

[00170] Example 9. The method of any of the preceding examples, wherein the method comprises reacting the Petition 870250090980, dated 06 / 10 / 2025, pp. 89 / 112 82 / 88 group of boronic acid pendant with Bronsted-Lowry acid and Bronsted-Lowry acid comprises an alkylsulfonic acid, an arylsulfonic acid, or an alkylarylsulfonic acid.

[00171] Example 10. The method of any of the preceding examples, wherein the method comprises reacting the pendant boronic acid group with Bronsted-Lowry acid and the Bronsted-Lowry acid comprises sulfuric acid or a derivative thereof.

[00172] Example 11. The method of any of the preceding examples, wherein the method comprises reacting the pendant boronic acid group with Bronsted-Lowry acid and the Bronsted-Lowry acid comprises a phosphoric acid, a phosphinic acid or a derivative thereof.

[00173] Example 12. The method of any of the preceding examples, wherein the method comprises reacting the pendant boronic acid group with Bronsted-Lowry acid and the Bronsted-Lowry acid comprises a carboxylic acid, a phenol or a derivative thereof.

[00174] Example 13. The method of any of the preceding examples, comprising additionally creating the functionalized polymer molecule with boronic acid.

[00175] Example 14. The method of example 13, in which creating the boronic acid-functionalized polymer molecule comprises functionalizing a polymer molecule. Petition 870250090980, dated 06 / 10 / 2025, pages 90 / 112 83 / 88 with a boronic acid group.

[00176] Example 15. The method of example 14, wherein the polymer molecule comprises a PBI polymer.

[00177] Example 16. The method of example 14, wherein the polymer molecule comprises an aromatic polymer molecule.

[00178] Example 17. The method of example 14, wherein the polymer molecule comprises a PTFE polymer molecule.

[00179] Example 18. The method of example 14, wherein the polymer molecule comprises a PCTFE polymer molecule.

[00180] Example 19. The method of example 14, wherein the polymer molecule comprises a cellulose polymer molecule.

[00181] Example 20. The method of example 14, wherein the polymer molecule comprises a polymer molecule functionalized with sulfonic acid.

[00182] Example 21. The method of example 14, in which functionalizing the polymer molecule with the boronic acid group involves borylating an aromatic ring in a repeating unit of the main chain.

[00183] Example 22. The method of example 21, wherein the polymer molecule comprises a PBI polymer molecule or a polystyrene polymer molecule. Petition 870250090980, dated 06 / 10 / 2025, pages 91 / 112 84 / 88

[00184] Example 23. The method of example 14, in which functionalizing the polymer molecule with the boronic acid group comprises linking a boronic acid-functionalized ligand to a secondary nitrogen in a repeating unit of the main chain.

[00185] Example 24. The method of example 23, in which the secondary nitrogen is included in a benzimidazole unit of the main chain.

[00186] Example 25. The method of any of Examples 14 to 24, in which functionalizing the polymer molecule with the boronic acid group comprises: activating a sulfonic acid group of a sulfonic acid-functionalized polymer molecule to a sulfonyl chloride, sulfonyl fluoride, or sulfonyl ester; and linking an amino group of an amino boronic acid ligand to the sulfonyl chloride, sulfonyl fluoride, or sulfonyl ester.

[00187] Example 26. The method of any of examples 14 to 25, in which functionalizing the polymer molecule with the boronic acid group comprises: activating a sulfonic acid group of a sulfonic acid-functionalized polymer molecule to a sulfonyl chloride, sulfonyl fluoride, or sulfonyl ester; linking an aromatic boronic acid to the sulfonyl chloride, sulfonyl fluoride, or sulfonyl ester; and protonating the aromatic boronic acid.

[00188] Example 27. A polymer molecule Petition 870250090980, dated 06 / 10 / 2025, pages 92 / 112 85 / 88 functionalized with tetra-coordinated boronic acid comprising: a main chain; and a tetra-coordinated boronic acid group attached to the main chain, the tetra-coordinated boronic acid group having the general formula — BFmXn(OH)(3-mn), where B has four covalent bonds and is covalently linked to a polymer main chain, side chain, or side group; m and n are each independently 0, 1, 2, or 3; the sum of m+n is 1, 2, or 3; And X is an anion other than fluoride.

[00189] Example 28. The tetra-coordinated boronic acid functionalized polymer molecule of example 27, wherein the tetra-coordinated boronic acid comprises a fluoroboric acid group, where m is 1, 2 or 3; n is 0, 1, or 2; and the sum of m+n is 1, 2, or 3.

[00190] Example 29. The tetra-coordinated boronic acid functionalized polymer molecule of example 28, wherein the fluoroboric acid group comprises a trifluoroboric acid group with the general formula —BF3.

[00191] Example 30. The tetra-coordinated boronic acid functionalized polymer molecule of example 28, in which the fluoroboric acid group has the formula —BF2OH.

[00192] Example 31. The tetra-coordinated boronic acid functionalized polymer molecule of example 28, in which the fluoroboric acid group has Petition 870250090980, dated 06 / 10 / 2025, pp. 93 / 112 86 / 88 the formula —BF(OH)2.

[00193] Example 32. The tetra-coordinated boronic acid functionalized polymer molecule of any of Examples 27 to 31, wherein the main chain comprises a repeating unit that includes a benzimidazole unit.

[00194] Example 33. The tetra-coordinated boronic acid functionalized polymer molecule of example 32, in which the boron atom is linked to a secondary amine of the benzimidazole unit via a ligand.

[00195] Example 34. The tetra-coordinated boronic acid functionalized polymer molecule of any of Examples 27 to 31, wherein: the main chain comprises a repeating unit that includes an aromatic ring; and the boron atom is covalently bonded to the aromatic unit.

[00196] Example 35. The tetra-coordinated boronic acid functionalized polymer molecule of example 34, wherein the main chain comprises polystyrene.

[00197] Example 36. The tetra-coordinated boronic acid functionalized polymer molecule of any of Examples 27 to 35, in which the tetra-coordinated boronic acid group is linked, directly or indirectly, to the main chain by a bond of Petition 870250090980, dated 06 / 10 / 2025, pp. 94 / 112 87 / 88 sulfonamide or a sulfone linkage.

[00198] Example 37. The tetra-coordinated boronic acid functionalized polymer molecule of any of Examples 27 to 36, wherein: the main chain comprises PTFE with a side chain; the side chain is a long side chain, a medium side chain, or a short side chain; and the boron atom is covalently bonded to the side chain.

[00199] Example 38. The tetra-coordinated boronic acid functionalized polymer molecule of any of Examples 27 to 37, where X is a conjugate base of a Bronsted-Lowry acid.

[00200] Example 39. The tetra-coordinated boronic acid functionalized polymer molecule of any of Examples 27 to 38, wherein the Bronsted-Lowry acid comprises an alkylsulfonic acid, an arylsulfonic acid, an alkylarylsulfonic acid, sulfuric acid, a phosphoric acid, a phosphinic acid, a carboxylic acid, a phenol, or a derivative of any of the foregoing.

[00201] Example 40. A membrane electrode assembly comprising: a first catalyst layer; a second catalyst layer; and a proton exchange membrane positioned between the first catalyst layer and the second catalyst layer; wherein at least one Petition 870250090980, dated 06 / 10 / 2025, pages 95 / 112 88 / 88 between the first catalyst layer, second catalyst layer and the proton exchange membrane is formed by a polymer molecule comprising a main chain and a tetra-coordinated boronic acid group attached to the main chain, the tetra-coordinated boronic acid group having the general formula —BFmXn(OH)(3-mn), where B has four covalent bonds and is covalently linked to a polymer main chain, side chain or side group; men are each independently 0, 1, 2 or 3; the sum of m+n is 1, 2 or 3; and X is an anion other than fluoride. Petition 870250090980, dated 06 / 10 / 2025, pp. 96 / 112

Claims

1 / 10 CLAIMS 1. A method for creating a tetra-coordinated boronic acid functionalized polymer molecule, characterized in that it comprises: reacting a pendant boronic acid group of a boronic acid functionalized polymer molecule with a fluoride reagent and / or a compound having the general formula HX, wherein HX is a Brønsted-Lowry acid.

2. A method according to claim 1, characterized in that the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized polybenzimidazole (PBI) polymer molecule.

3. Method according to claim 1, characterized in that the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized aromatic polymer molecule.

4. Method according to claim 1, characterized in that the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized PTFE polymer molecule.

5. Method according to claim 1, characterized in that the boronic acid-functionalized polymer molecule comprises a PCTFE polymer molecule functionalized with boronic acid.

6. Method according to claim 1, characterized in that the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized cellulose polymer molecule.

7. Method according to claim 1, characterized in that: the method comprises reacting the pendant boronic acid group with the fluoride reagent; and the fluoride reagent comprises hydrogen fluoride (HF), lithium fluoride (LiF), sodium fluoride (NaF), potassium fluoride (KF), potassium bifluoride (KHF2), cesium fluoride (CsF), ammonium fluoride (NH4F), ammonium bifluoride (NH4F2) or a tetraalkylammonium fluoride having the general formula NR4F, wherein each R is independently hydrogen or a substituted or unsubstituted alkyl or aryl group.

8. Method according to claim 7, characterized in that: the method comprises reacting the pendant boronic acid group with the fluoride reagent; and the fluoride reagent comprises boron trifluoride.

9. Method according to claim 1, the method being characterized in that it comprises reacting the pendant boronic acid group with the Brønsted-Lowry acid and the Brønsted-Lowry acid comprises an alkylsulfonic acid, an arylsulfonic acid or an alkylarylsulfonic acid.

10. Method according to claim 1, the method being characterized in that it comprises reacting the pendant boronic acid group with Brønsted-Lowry acid, and the Brønsted-Lowry acid comprises sulfuric acid or a derivative thereof.

11. Method according to claim 1, the method being characterized in that it comprises reacting the pendant boronic acid group with Brønsted-Lowry acid, and the Brønsted-Lowry acid comprises a phosphoric acid, a phosphinic acid or a derivative thereof.

12. Method according to claim 1, the method being characterized in that it comprises reacting the pendant boronic acid group with Brønsted-Lowry acid, and the Brønsted-Lowry acid comprises a carboxylic acid, a phenol or a derivative thereof.

13. Method according to claim 1, characterized in that it further comprises creating the boronic acid-functionalized polymer molecule.

14. Method according to claim 13, characterized in that the creation of the boronic acid-functionalized polymer molecule comprises the functionalization of a polymer molecule with a boronic acid group.

15. Method according to claim 14, characterized in that the polymer molecule comprises a PBI polymer molecule.

16. Method according to claim 14, characterized in that the polymer molecule comprises an aromatic polymer molecule.

17. Method according to claim 14, characterized in that the polymer molecule comprises a PTFE polymer molecule.

18. Method according to claim 14, characterized in that the polymer molecule comprises a polymer molecule functionalized with sulfonic acid.

19. Method according to claim 14, characterized in that the polymer molecule comprises a PCTFE polymer molecule functionalized with boronic acid.

20. Method according to claim 1, characterized in that the boronic acid-functionalized polymer molecule comprises a boronic acid-functionalized cellulose polymer molecule.

21. Method, according to claim 14, characterized in that the functionalization of the polymer molecule with the boronic acid group comprises subjecting an aromatic ring in a repeating unit of a main chain of the polymer molecule to borylation.

22. Method according to claim 19, characterized in that the polymer molecule comprises a PBI polymer molecule or a polystyrene polymer molecule.

23. Method according to claim 14, characterized in that the functionalization of the polymer molecule with the boronic acid group comprises linking a boronic acid-functionalized ligand to a secondary nitrogen in a repeating unit of a backbone of the polymer molecule.

24. Method according to claim 23, characterized in that the secondary nitrogen is included in a benzimidazole unit of the main chain.

25. Method according to claim 14, characterized in that the functionalization of the polymer molecule with the boronic acid group comprises: activating a sulfonic acid group of a sulfonic acid-functionalized polymer molecule to a sulfonyl chloride, sulfonyl fluoride or sulfonyl ester; and linking an amino group of an amino boronic acid ligand to sulfonyl chloride, sulfonyl fluoride or sulfonyl ester.

26. A method according to claim 14, characterized in that the functionalization of the polymer molecule with the boronic acid group comprises: activating a sulfonic acid group of a sulfonic acid-functionalized polymer molecule to a sulfonyl chloride, sulfonyl fluoride, or sulfonyl ester; linking an aromatic boronic acid to the sulfonyl chloride, sulfonyl fluoride, or sulfonyl ester; and subjecting the aromatic boronic acid to protonation.

27. A tetra-coordinated boronic acid functionalized polymer molecule, characterized in that it comprises: a main chain; and a tetra-coordinated boronic acid group attached to the main chain, the tetra-coordinated boronic acid group having the general formula —BFmXn(OH)(3-mn) wherein the boron atom (B) has four covalent bonds and is covalently bonded to a polymer main chain, side chain or side group; m and n are each independently 0, 1, 2 or 3; the sum of m+n is 1, 2 or 3; and X is an anion other than fluoride.

28. Polymer molecule functionalized with tetra-coordinated boronic acid, according to claim 27, characterized in that the tetra-coordinated boronic acid comprises a fluoroboric acid group where m is 1, 2 or 3; n is 0, 1 or 2; and the sum of m+n is 1, 2 or 3.

29. A tetra-coordinated boronic acid functionalized polymer molecule according to claim 28, characterized in that the fluoroboric acid group comprises a trifluoroboric acid group having the general formula —BF3.

30. A tetra-coordinated boronic acid functionalized polymer molecule according to claim 28, characterized in that the fluoroboric acid group has the formula —BF2OH.

31. A tetra-coordinated boronic acid functionalized polymer molecule according to claim 28, characterized in that the fluoroboric acid group has the formula —BF(OH)2.

32. Tetra-coordinated boronic acid functionalized polymer molecule according to claim 27, characterized in that the main chain comprises a repeating unit that includes a benzimidazole unit.

33. Tetra-coordinated boronic acid functionalized polymer molecule according to claim 32, characterized in that the boron atom is linked to a secondary amine of the benzimidazole unit by means of a ligand. Petition 870250070535, dated 11 / 08 / 2025, pp. 50 / 54 8 / 10 34. A tetra-coordinated boronic acid functionalized polymer molecule according to claim 27, characterized in that: the main chain comprises a repeating unit that includes an aromatic ring; and the boron atom is covalently bonded to the aromatic unit.

35. Tetra-coordinated boronic acid functionalized polymer molecule according to claim 34, characterized in that the main chain comprises polystyrene.

36. A polymer molecule functionalized with tetra-coordinated boronic acid, according to claim 27, characterized in that the tetra-coordinated boronic acid group is linked, directly or indirectly, to the main chain or to a side chain by a sulfonamide linkage or a sulfone linkage.

37. Tetra-coordinated boronic acid functionalized polymer molecule according to claim 27, characterized in that: the main chain comprises PTFE having a side chain; the side chain is a long-sided chain, a medium-sided chain or a short-sided chain; and the boron atom is covalently bonded to the side chain. Petition 870250070535, dated 11 / 08 / 2025, page 51 / 54 9 / 10 38. A polymer molecule functionalized with tetra-coordinated boronic acid, according to claim 27, characterized in that X is a conjugate base of a Brønsted-Lowry acid.

39. A tetra-coordinated boronic acid functionalized polymer molecule according to claim 38, characterized in that the Brønsted-Lowry acid comprises an alkylsulfonic acid, an arylsulfonic acid, an alkylarylsulfonic acid, sulfuric acid, a phosphoric acid, a phosphinic acid, a carboxylic acid, a phenol, or a derivative of any of the foregoing.

40. Membrane electrode assembly, characterized in that it comprises: a first catalyst layer; a second catalyst layer; and a proton exchange membrane positioned between the first catalyst layer and the second catalyst layer; wherein at least one of the first catalyst layer, the second catalyst layer and the proton exchange membrane is formed by a polymer molecule comprising a main chain and a tetra-coordinated boronic acid group attached to the main chain, the tetra-coordinated boronic acid group having the general formula — Petition 870250070535, dated 11 / 08 / 2025, page 52 / 54 10 / 10 BFmXn (OH) (3-mn) where B has four covalent bonds and is covalently linked to a polymer main chain, side chain or side group; m and n are each independently 0, 1, 2 or 3; the sum of m+n is 1, 2 or 3; and X is an anion different from fluoride. Petition 870250070535, dated 11 / 08 / 2025, pp. 53 / 54

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