WO2019079513A1

WO2019079513A1 - Polymers having stable cationic pendant groups for use as anion exchange membranes and ionomers

Info

Publication number: WO2019079513A1
Application number: PCT/US2018/056370
Authority: WO
Inventors: Yushan Yan; Lan Wang; Junhua Wang; Bingjun Xu; Yun Zhao
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-10-17
Filing date: 2018-10-17
Publication date: 2019-04-25
Anticipated expiration: 2020-04-17

Abstract

SEBS block copolymers or norbornene-pyrrolidinium random or block copolymers with pendant cationic groups are provided which have an alkaline-stable cation introduced into a rigid aromatic polymer backbone free of ether bonds. Hydroxide exchange membranes or hydroxide exchange ionomers formed from these polymers exhibit superior chemical stability, hydroxide conductivity, decreased water uptake, good solubility in selected solvents, and improved mechanical properties in an ambient dry state as compared to conventional hydroxide exchange membranes or ionomers. Hydroxide exchange membrane fuel cells comprising the SEBS block copolymers or norbornene-pyrrolidinium random or block copolymers with pendant cationic groups exhibit enhanced performance and durability at relatively high temperatures.

Description

POLYMERS HAVING STABLE CATIONIC PENDANT GROUPS FOR USE AS ANION EXCHANGE MEMBRANES AND IONOMERS

GOVERNMENT LICENSE RIGHTS

[0001]This invention was partly made with Government support under grant DE- 0006964 and DE-AR0000771 awarded by Office of Energy Efficiency and Renewable Energy of the United States Department of Energy. The Government has certain rights in the invention.

FIELD OF THE INVENTION

[0002] Anion exchange polymers capable of forming anion-exchange

membranes (AEMs) and ionomers (AEIs) are provided for use in anion exchange membrane fuel cells (AEMFCs). More specifically, hydroxide exchange polymers are provided which are capable of forming hydroxide-exchange membranes (HEMs), hydroxide exchange membrane electrolyzers (HEMEL), and ionomers (HEIs) for use in hydroxide exchange membrane fuel cells (HEMFCs).

BACKGROUND OF THE INVENTION

[0003] Proton exchange membrane fuel cells (PEMFCs) are considered to be clean and efficient power sources. Steele et al., Nature 2001 , 414, 345. However, the high cost and unsatisfactory durability of catalysts are major barriers for large-scale commercialization of PEMFCs. Borup et al., Chem Rev 2007, 107, 3904. By switching the polymer electrolyte from an "acidic" condition to a "basic" one, HEMFCs are able to work with non-precious metal catalysts and the catalysts are expected to be more durable. Other cheaper fuel cell components are also possible such as metal bipolar plates. Varcoe, et al., Fuel Cells 2005, 5, 187; Gu et al., Angew Chem Int Edit 2009, 48, 6499; Gu et al. , Chem Commun 2013, 49, 131 . However, currently available HEMs and HEIs exhibit low alkaline/chemical stability, low hydroxide conductivity, high water uptake, and low mechanical integrity under dry conditions, especially after wet-dry cycles.

[0004]The biggest challenge for HEMs/HEIs at present is achieving a high chemical stability at desired operation temperatures of 80 °C or more, and ideally 95 °C or more (e.g., in the presence of nucleophilic hydroxide ions). Varcoe et al., Energ Environ Sci 2014, 7, 3135. The most commonly encountered cationic functional groups (e.g., benzyl trimethyl ammonium and alkyl chain ammonium) can undergo a number of degradation processes in the presence of hydroxide ions nucleophiles by direct nucleophilic substitution and Hofmann elimination. Moreover, the polymer backbone of most base polymers for HEM/HEI applications (e.g., polysulfone and poly(phenylene oxide)) unavoidably contains ether linkages along the backbone, which makes the HEMs/HEIs potentially labile under high pH conditions. Lee et al., Acs Macro Lett 2015, 4, 453; Lee et al. , Acs Macro Lett 2015, 4, 814. The strongly nucleophilic hydroxide ions attack these weak bonds and degrade the polymer backbone. Thus, alternative cationic groups, organic tethers, and polymer backbones are needed to enhance chemical stability of HEMs/HEIs.

[0005] Another concern regarding current HEMs/HEIs is their hydroxide conductivity. In comparison to Nafion, HEMs have intrinsically lower ionic conductivities under similar conditions, because the mobility of OH^" is lower than that of H⁺. Hibbs et al., Chem Mater 2008, 20, 2566. Greater ion-exchange capacity (IEC) is needed for HEMs/HEIs to achieve greater hydroxide conductivity. However, high IEC usually leads to a membrane having high water uptake (i.e. , a high swelling ratio), decreasing the morphological stability and mechanical strength of the membrane, especially after repeated wet-dry cycles. This highly swollen state when wet is a major reason for decreased flexibility and brittleness of HEMs when dry. The removal of the trade-off between high hydroxide conductivity and low water uptake has been a major setback in designing high-performance HEMs/HEIs. Pan et al., Energ Environ Sci 2013, 6, 2912. Chemical cross-linking, physical reinforcement, side-chain polymerization, and block- copolymer architecture have been tried to reduce water uptake while maintaining acceptable hydroxide conductivity, but these techniques bring challenging problems, e.g., reduced mechanical flexibility, decreased alkaline stability, and/or increased cost. Gu et al., Chem Commun 2011 , 47, 2856; Park et al., Electrochem Solid St 2012, 15, B27; Wang et al., Chemsuschem 2015, 8, 4229; Ran et al., Sci Rep-Uk 4;

Tanaka et al., J Am Chem Soc 2011 , 133, 10646. Additionally, almost all side-chain or block-copolymer HEMs are based on flexible aliphatic polymer chains due to limited available synthesis methods. As a result, the membranes still cannot provide morphological stability (low swell ratio) at high lECs and high temperature. Wang et al., Chemsuschem 2015, 8, 4229; Ran et al., Sci Rep-Uk 20 4, 4; Marino et al.,

Chemsuschem 2015, 8, 513; Li et al, M. Macromolecules 2015, 48, 6523.

[0006] An additional obstacle to using HEMs is achievement of mechanical flexibility and strength in an ambient dry state. Most HEMs exhibit low mechanical strength and are very brittle in a completely dry state especially after being completely swollen. It is difficult to obtain and handle thin membranes that are large in size as needed for commercial use of HEMs. Without good mechanical properties, the ionomers cannot form and keep an adequate triple phase structure in the fuel cell electrode at high temperature, such as at or above 80 °C. Li et al., J Am Chem Soc 2013, 135, 10124.

[0007]Another highly desirable feature of an HEI is that the polymer be soluble in a mixture of lower boiling alcohol and water but insoluble in pure alcohol or water so that the HEIs can be readily incorporated into an electrode catalyst layer yet not be dissolved away by water or alcohol.

[0008] PEMFCs have recently been deployed as zero-emission power sources in commercially sold automobiles, with demonstrated long driving range and short refuelling time, which are two features preferred for customer acceptance. However, PEMFCs use platinum electrocatalysts and are not yet cost competitive with gasoline engines. Major approaches to PEMFC cost reduction include development of low- platinum-loading, high power density membrane electrode assemblies (MEAs), and platinum-group-metal-free (PGM-free) cathode catalysts. A fundamentally different pathway to low cost fuel cells is to switch from PEMFCs to hydroxide exchange membrane fuel cells (HEMFCs) that, due to their basic operating environment, can work with PGM-free anode and cathode catalysts, and thus are potentially economically viable. To replace PEMFCs, however, HEMFCs have to provide a performance that matches PEMFCs, performance which in turn requires highly active anode and cathode catalysts as well as the highly chemically stable, ionically conductive, and mechanically robust hydroxide exchange membranes (HEMs)/hydroxide exchange ionomers (HEIs) to build an efficient triple phase boundary and thus drastically improve the utilization of the catalyst particles and reduce the internal resistance.

[0009] HEMs/HEIs are typically composed of organic cations tethered on a polymer backbone, with OH- being the balancing anion. A chemically stable HEM/HEI requires a stable organic cation and a stable polymer backbone. These hydroxide conductive organic cations have been obtained by introducing quaternary ammonium, imidazolium, guanidinium, phosphonium, sulfonium, ruthenium and cobaltocenium using chloromethylation of aromatic rings or bromination on the benzylic methyl groups of the polymers. Various polymer backbone structures-poly(olefin)s, poly(styrene)s poly(phenylene oxide)s, poly(phenylene)s, poly(arylene ether)s-have been investigated recently. Most HEMs/HEIs based on traditional cation groups (such as benzyl trimethyl ammonium) and aromatic polymer backbones (such as polysulfone) have low alkaline/chemical stability, low hydroxide conductivity, high water uptake, and poor mechanical properties when dry. Most membranes and ionomers are not thermoplastic materials in which the glass transition temperature (T_g) is greater than thermal degradation temperature (Td). Therefore, these materials could not provide efficient triple phase boundary through use of a hot press method to improve fuel cell performance.

SUMMARY OF THE INVENTION

[0010] In one aspect of the invention, an anion exchange polymer is provided. The anion exchange polymer can comprise either a styrene-ethylene-butylene-styrene (SEBS)-type block copolymer or a norbornene-pyrrolidinium random or block copolymer.

[0011]The SEBS block copolymer can comprise the structure A-B-A, wherein each A is independently a polystyrene-containing block comprising structural units of Formulae 1 and 2 or Formulae 1 and 3, and B is a polyalkylene block comprising polyethylene structural unit 4 and polybutylene structural unit 5. The structural units of Formulae 1 , 2, 3, 4 and 5 ha

wherein: D is a nitrogen-containing heterocycle comprising an optionally substituted pyrrole, pyrroline, pyrazole, pyrazoline, imidazole, imidazoline, triazole, pyridine, triazine, pyrazine, pyridazine, pyrimidine, azepine, quinoline, piperidine, pyrrolidine, pyrazolidine, imidazolidine, azepane, isoxazole, isoxazoline, oxazole, oxazoline, oxadiazole, oxatriazole, dioxazole, oxazine, oxadiazine, isoxazolidine, morpholine, thiazole, isothiazole, oxathiazole, oxathiazine, or caprolactam, wherein each substituent is independently alkyl, alkenyl, alkynyl, aryl, or aralkyl; Ri , R6 and R7 are each independently alkylene; R2, R3, R₄, and R5 are each independently alkyl, alkenyl, aryl, or alkynyl; q is 0, 1 , 2, 3, 4, 5, or 6; m, n, xi , and x₂ are each independently a mole fraction from about 0.01 to about 0.99; X^" is an anion; and Z is N or P.

[0012]The norbornene-pyrrolidinium random or block copolymer can comprise structural units of Formulae 6 and 7 or Formulae 6 and 8, wherein Formulae 6, 7 and 8 have the structure:

wherein: p is 1 , 2, 3, 4, 5, 6, 7 or 8; R12 and R13 are each independently halide, alkyl, alkenyl, alkynyl or aryl and the alkyl, alkenyl, alkynyl or aryl are optionally substituted with halide; and X^" is an anion. [0013] In another aspect of the invention, a method of making the SEBS block copolymer is provided. The method comprises: reacting an acylating agent and an SEBS polymer in the presence of an organic solvent and a polymerization catalyst to form an acylated SEBS polymer; reacting the acylated SEBS polymer and a deacylating agent in the presence of an organic solvent to form a deacylated SEBS polymer; and reacting the deacylated SEBS polymer and either a quaternary ammonium or phosphonium compound or the nitrogen-containing heterocycle in the presence of an organic solvent to form the SEBS block copolymer. The quaternary ammonium or phosphonium compound has the formula:

the SEBS polymer comprises the structural units of Formulae 1 , 4 and 5; the acylated SEBS polymer comprises the structural units of Formulae 1 , 2A, 4 and 5; the deacylated SEBS polymer comprises the structural units of Formulae 1 , 2B, 4 and 5; and the formulae 2A and

; and

wherein Ri₄ is alkylene, and X is an anion.

[0014] In yet another aspect of the invention, a method of making the norbornene-pyrrolidinium random or block copolymer is provided. The method comprises reacting norbornene, a haloalkylnorbornene, or a combination thereof in the presence of an organic solvent and a polymerization catalyst to form a norbornene polymer; and reacting the norbornene polymer with a secondary amine or a nitrogen- containing heterocycle in the presence of an organic solvent to form the norbornene- pyrrolidinium random or block copolymer. The secondary amine has the formula H N R15R16 wherein R15 and R16 are each independently alkyl; the norbornene polymer comprises structural units of formulae 6 and 7A; and the structural unit having formula 7A has the structure:

wherein X is a halide.

[0015] In another aspect of the invention, an hydroxide exchange polymer is provided, the polymer comprising a poly(norbornene-pyrrolidinium) backbone free of ether linkages or a styrene-ethylene-butylene-styrene (SEBS) backbone free of ether linkages, and having water uptake not more than 150% based on the dry weight of the polymer when immersed in pure water at room temperature, or having hydroxide conductivity in pure water at room temperature of at least 20 mS/cm, wherein at least one of the following: the polymer is stable to degradation (as evidenced by no change in conductivity) when immersed in 1 M potassium hydroxide at 80 °C for 500 hours; or the polymer has a tensile strength of at least 40 MPa and/or elongation at break of at least 100%; or the polymer has a tensile strength of at least 60 MPa and/or elongation at break of at least 150%.

[0016] Another hydroxide exchange polymer is also provided, the polymer comprising a poly(norbornene-pyrrolidinium) backbone free of ether linkages or a styrene-ethylene-butylene-styrene (SEBS) backbone free of ether linkages, and having: a peak power density of at least 160 mW/cm² when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at 20% as an hydroxide exchange ionomer in cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a 50% Pt/C catalyst and catalyst loading of 0.4 mg Pt/cm2, and test conditions being hydrogen and oxygen flow rates of 0.6 LJmin, no back pressure, cell temperature of 60 °C, and anode and cathode humidifiers at 65 °C and 65 °C, respectively; or a decrease in voltage over 5.5 hours of operation of not more than 20% and an increase in resistance over 5.5 hours of operation of not more than 20% when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at 20% as an hydroxide exchange ionomer in cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a 50% Pt/C catalyst and catalyst loading of 0.4 mg Pt/cm², and test conditions being constant current density of 400 mA/cm², hydrogen and oxygen flow rates of 0.6 L/min, no back pressure, cell temperature of 60 °C, and anode and cathode humidifiers at 65 °C and 65 °C, respectively.

[0017] In yet another aspect of the invention, a method of making an anion exchange polymer membrane comprising the anion exchange polymer as described herein is provided, the method comprising: dissolving the SEBS block copolymer or the norbornene-pyrrolidinium random or block copolymer in a solvent to form a polymer solution; casting the polymer solution to form a polymer membrane; and exchanging anions of the polymer membrane with hydroxide, bicarbonate, or carbonate ions or a combination thereof to form the anion exchange polymer membrane. [0018] An anion exchange membrane configured and sized to be suitable for use in a fuel cell is also provided, the membrane comprising the anion exchange polymer as described herein.

[0019] An anion exchange membrane fuel cell is provided, the fuel cell comprising the anion exchange polymer as described herein.

[0020] Also provided is a reinforced electrolyte membrane configured and sized to be suitable for use in a fuel cell, the membrane comprising a porous substrate impregnated with the anion exchange polymer as described herein.

[0021] Other objects and features will be in part apparent and in part pointed out hereinafter.

BRI EF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 illustrates an exemplary hydroxide exchange membrane fuel cell;

[0023] Figure 2 depicts an ¹ H NMR spectrum of a SEBS-COCsBr polymer;

[0024] Figure 3 depicts an ¹ H NMR spectrum of a SEBS-C6Br polymer; and

[0025] Figure 4 depicts a graph of SEBS- CeQN HEMFC performance (SEBS- C6QN membrane, 5 μιη and AS-4 ionomer) when tested at 60 °C under these test conditions: ionomer (20 wt%), 0.4 mg Pt cm-2 on both anode and cathode, humidifier temperatures of 65 °C and 65 °C for H2 and 02, respectively, gas flow rate of 0.6 L min-1 and no back pressure.

[0026] Corresponding reference characters indicate corresponding parts throughout the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] HEMs/HEIs formed from functionalized polymers with various pendant cationic groups and having intrinsic hydroxide conduction channels have been discovered which simultaneously provide improved chemical stability, conductivity, water uptake, good solubility in selected solvents, mechanical properties, and other attributes relevant to HEM/HEI performance. The functionalized polymers have an alkaline-stable cation, introduced into a rigid aromatic polymer backbone free of ether bonds. The attachment of the pendant side chains to the rigid aromatic polymer backbone of the polymer allows fine tuning of the mechanical properties of the membrane and incorporation of alkaline stable cations, such as imidazoliums, phosphoniums and ammoniums, provides enhanced stability to the polymer.

HEMs/HEIs formed from these polymers exhibit superior chemical stability, anion conductivity, decreased water uptake, good solubility in selected solvents, and improved mechanical properties in an ambient dry state as compared to conventional HEM/HEIs. The inventive HEMFCs exhibit enhanced performance and durability at relatively high temperatures.

[0028] In one aspect of the invention, an anion exchange polymer is provided. The anion exchange polymer can comprise either a styrene-ethylene-butylene-styrene (SEBS)-type block copolymer or a norbornene-pyrrolidinium random or block copolymer.

[0029]The SEBS block copolymer can comprise the structure A-B-A, wherein each A is independently a polystyrene-containing block comprising structural units of Formulae 1 and 2 or Formulae 1 and 3, and B is a polyalkylene block comprising polyethylene structural unit 4 and polybutylene structural unit 5. The structural units of Formulae 1 , 2, 3, 4 and 5 have the structures:

wherein:

D is a nitrogen-containing heterocycle comprising an optionally substituted pyrrole, pyrroline, pyrazole, pyrazoline, imidazole, imidazoline, triazole, pyridine, triazine, pyrazine, pyridazine, pyrimidine, azepine, quinoline, piperidine, pyrrolidine, pyrazolidine, imidazolidine, azepane, isoxazole, isoxazoline, oxazole, oxazoline, oxadiazole, oxatriazole, dioxazole, oxazine, oxadiazine, isoxazolidine, morpholine, thiazole, isothiazole, oxathiazole, oxathiazine, or caprolactam, wherein each substituent is independently alkyl, alkenyl, alkynyl, aryl, or aralkyl;

Ri , R6 and R7 are each independently alkylene;

R2, R3, R4, and R5 are each independently alkyl, alkenyl, aryl, or alkynyl;

q is O, 1 , 2, 3, 4, 5, or 6;

m, n, xi, and x₂ are each independently a mole fraction from about 0.01 to about 0.99;

X^" is an anion; and

Z is N or P.

[0030] In the SEBS block copolymer, the ratio of the mole fraction of the structural units of Formulae 1 and 2 or Formulae 1 and 3 in the polymer to the mole fraction of the structural unit of Formulae 4 and 5 in the polymer is from about 0.01 to about 0.99, preferably from about 0.2 to about 0.8, and more preferably from about 0.4 to about 0.6.

[0031] In any of the structural units described herein, preferred mole fractions (e.g., for m, n, x, y, z, xi, X2, zi or z2) can be from about 0.05 to about 0.95, from about 0.05 to about 0.9, from about 0.05 to about 0.8, from about 0.05 to about 0.7, or from about 0.05 to about 0.6, from about 0.05 to about 0.5, or from about 0.05 to about 0.4, from about 0.05 to about 0.3, or from about 0.05 to about 0.2. All combinations of these ranges of mole fractions can be combined for the structural units of any anion exchange polymer as described herein.

[0032] In the structural unit of formula 2, preferred substituents can include, for example, where (1 ) Ri and R6 are each independently C1-C22 alkylene, R2, R3, R4, and Rs are each independently C1-C6 alkyl, q is 0, 1 , 2, 3, 4, 5, or 6, X2 is from about 0.01 to about 0.99, and Z is N or P; or (2) Ri and R6 are each independently C1-C6 alkylene, R2, R3, R4, and R5 are each independently C1-C6 alkyl, q is 0, 1 , 2, or 3, X2 is from about 0.01 to about 0.99, and Z is N or P; or (3) Ri and R6 are each independently C8-C22 alkylene; R2, R3, R4, and R5 are each independently C1-C6 alkyl; q is 0, 1 , 2, or 3, X2 is from about 0.01 to about 0.99, and Z is N or P; or (4) Ri and R6 are each independently C2-C6 alkylene, R2, R3, R4, and R5 are methyl, q is 1 , X2 is from about 0.01 to about 0.99, and Z is N; or (5) Ri and R6 are n-hexylene, R₂, R3, R₄, and R5 are methyl, q is 1 , X2 is from about 0.01 to about 0.99, and Z is N.

[0033] In the structural unit of formula 3, preferred substituents can include, for example, where (1 ) R7 is C1-C22 alkylene, X2 is from about 0.01 about 0.99, and the nitrogen-containing heterocycle D comprises a fully substituted pyrrole, pyrroline, pyrazole, pyrazoline, imidazole, imidazoline, triazole, pyridine, triazine, pyrazine, pyridazine, pyrimidine, azepine, or quinoline, wherein each substituent is independently alkyl or aryl; (2) R7 is C1 -C6 alkylene, X2 is from about 0.01 to about 0.99, and the nitrogen-containing heteroc cle D comprises an imidazole having the formula:

wherein Rs, R9, R10, and Rn are each independently optionally substituted alkyl, alkenyl, alkynyl, or aryl; (3) R7 is C7-C22 alkylene, X2 is from about 0.01 to about 0.99, and the nitrogen-containing heterocycle D comprises the imidazole of formula 10 wherein Rs, R9, and Rio are each independently C1-C6 alkyl, and R11 is 2,4,6- alkylphenyl; or (4) R7 is n-hexylene, X2 is from about 0.01 to about 0.99, and the nitrogen-containing heterocycle D comprises 1 -butyl-2-mesityl-4,5-dimethyl-1 /-/- imidazole which has the formula:

[0034] In the structural unit of formula 4, preferred ranges of n can be from about 0.05 to about 0.95, from about 0.1 to about 0.9, from about 0.2 to about 0.8, from about 0.3 to about 0.7, or from about 0.4 to about 0.6.

[0035] In the structural unit of formula 5, preferred ranges of m can be from about 0.05 to about 0.95, from about 0.1 to about 0.9, from about 0.2 to about 0.8, from about 0.3 to about 0.7, or from about 0.4 to about 0.6.

[0036]The norbornene-pyrrolidinium random or block copolymer can comprise structural units of Formulae 6 and 7 or Formulae 6 and 8, wherein Formulae 6, 7 and 8 have the structure:

wherein: p is 1 , 2, 3, 4, 5, 6, 7 or 8; R12 and R13 are each independently halide, alkyl, alkenyl, alkynyl or aryl and the alkyl, alkenyl, alkynyl or aryl are optionally substituted with halide; and X- is an anion.

[0037] In the norbornene-pyrrolidinium random or block copolymer, the ratio of the mole fraction of the structural unit of Formula 7 or 8 to the mole fraction of the structural unit of Formula 6 in the anion exchange polymer is from about 0.01 to 1 .

[0038] In the structural unit of formula 7, preferred substituents can include, for example, where R12 and R13 are each independently C1-C22 alkyl, C1-C6 alkyl such as methyl, ethyl, n-propyl, n-butyl, n-pentyl or n-hexyl, or Cs-C22 alkyl.

[0039] In the structural unit of formula 8, preferred ranges of p can be 1 , 2 or 3.

[0040] In the structural unit of formula 7 or 8, preferred substituents for the anion X^" can comprise a halide, BF₄ ^~, PF6^", CO3^2" or HCO3^", and more preferably a halide,

[0041] In any of the anion exchange polymers described herein, the anion X or X- can comprise a halide, BF₄ ^~ PF6^~, CO3^2" or HCO3-, and more preferably a halide, CO3^2"

[0042] An SEBS block copolymer as described herein can be prepared by a method which comprises reacting the SEBS polymer and an acylating agent in the presence of an organic solvent and a polymerization catalyst to form an acylated SEBS polymer; reacting the acylated SEBS polymer and a deacylating agent in the presence of an organic solvent to form a deacylated SEBS polymer; and reacting the deacylated SEBS polymer with the quaternary ammonium or phosphonium compound or the nitrogen-containing heterocycle in the presence of an organic solvent to form the SEBS block copolymer. The SEBS block copolymer can be reacted with a base to exchange the anion of the SEBS block copolymer for the anion of the base.

[0043]The reaction scheme with use of the quaternary ammonium or

phosphonium compound is depicted below:

deacylating agent

[0044]The SEBS polymer can comprise the structural units of Formulae 1 , 4 and A representative SEBS polymer has the formula:

wherein: m, n, x, y, and z are each independently from about 0.01 to about 0.99; and X^" is an anion.

[0045]The acylated SEBS polymer can comprise the structural units of Formulae 1 , 2A, 4 and 5. A representative acylated SEBS polymer has the formula:

wherein: Ri₄ is alkylene; m, n, x1 , x2, y, z1 , and z2 are each independently from about 0.01 to about 0.99; and X^" is an anion.

[0046] The formul

wherein Ri₄ is alkylene, and X is an anion.

[0047]The deacylated SEBS polymer can comprise the structural units of Formulae 1 , 2B, 4 and 5. A representative deacylated SEBS polymer has the formula:

wherein: Ri₄ is alkylene; m, n, x1 , x2, y, z1 and z2 ar eeach independently from about 0.01 to about 0.99; and X- is an anion.

[0048]The formul

wherein Ri₄ is alkylene, and X is an anion.

[0049] The acylating agent can comprise an acyl halide.

[0050] The deacylating agent can comprise triethylsilane, hydrogen, hydrazine, diphenylsilane, aluminium nickel alloy, or dimethylmonochlorosilane.

[0051]The nitrogen-containing heterocycle comprises an optionally substituted pyrrole, pyrroline, pyrazole, pyrazoline, imidazole, imidazoline, triazole, pyridine, triazine, pyrazine, pyridazine, pyrimidine, azepine, quinoline, piperidine, pyrrolidine, pyrazolidine, imidazolidine, azepane, isoxazole, isoxazoline, oxazole, oxazoline, oxadiazole, oxatriazole, dioxazole, oxazine, oxadiazine, isoxazolidine, morpholine, thiazole, isothiazole, oxathiazole, oxathiazine, or caprolactam, wherein each substituent is independently alkyl, alkenyl, alkynyl, aryl, or aralkyl. Preferably, the nitrogen- containing heterocycle is unsaturated such as pyrrole, pyrroline, pyrazole, pyrazoline, imidazole, imidazoline, triazole, pyridine, triazine, pyrazine, pyridazine, pyrimidine, azepine, or quinoline, and each substitutable position of the heterocycle is substituted independently with alkyl (e.g., methyl, ethyl, propyl, n-butyl) or aryl groups (e.g., phenyl with alkyl substituents). For example, the nitrogen-containing heterocycle can comprise an imidazole having the formula 10 wherein Rs, R9, Rio.and Rn are each independently optionally substituted alkyl, alkenyl, alkynyl, or aryl. An example of such as imidazole is 1 -butyl-2-mesityl-4,5-dimethyl-1 /-/-imidazole-imidazole. [0052]The quaternary ammonium or phosphonium compound has the formula:

wherein: Ri and R6 are each independently alkylene; R2, R3, R₄, and R5 are each independently alkyl, alkenyl, aryl, or alkynyl; q is 0, 1 , 2, 3, 4, 5, or 6; X- is an anion; and Z is N or P.

[0053] Preferably, Ri and R6 are each independently C1-C22 alkylene, such as C1-C6 alkylene (e.g. , ethylene, n-propylene, n-pentylene or n-hexylene), or Cs-C22 alkylene; R2, R3, R4, and R5 are each independently C1-C6 alkyl such as methyl, ethyl, n-propyl, n-butyl, isobutyl, tert-butyl, pentyl and hexyl; q is 1 , 2, 3, 4, 5, or 6; X^" is a halide; and Z is N.

[0054] The base used in the methods described herein can comprise an hydroxide-containing base such as sodium hydroxide or potassium hydroxide; a bicarbonate-containing base such as sodium bicarbonate or potassium bicarbonate; or a carbonate-containing base such as sodium carbonate or potassium carbonate.

[0055]The acylation of SEBS can be a Friedel-Crafts acylation reaction.

[0056] The portion of the reaction scheme with use of the nitrogen-containing heterocycle is depicted below:

[0057] For example, the SEBS polymer and an acylating agent such as a haloalkanoyi halide (e.g., 6-bromohexanoyl chloride) can be placed in a stirred container and dissolved or dispersed into an organic solvent such as methylene chloride. A polymerization catalyst such as aluminium chloride in a solvent can then be added dropwise over up to 60 minutes at -78 to 60 °C. Thereafter, the reaction is continued at this temperature for about 1 to about 120 hours. The resulting solution is poured slowly into an aqueous solution of ethanol. The product obtained is filtered, washed with water and ethanol and dried completely under vacuum to form an acylated SEBS polymer (such as an SEBS polymer having haloalkanoyi substituents on at least a portion of the styrene of the SEBS polymer).

[0058] Next, the acylated SEBS polymer is dissolved into an organic solvent in a stirred container. A deacylating agent (such as triethylsilane) in the presence of an organic solvent (such as trifluoroacetic acid) is added quickly, and the solution is stirred at 0 to 100 °C for about 1 to about 120 hours. The resulting solution is poured slowly into an aqueous solution of ethanol. The product obtained is filtered, washed with water and ethanol and dried completely under vacuum to form the deacylated SEBS polymer (such as an SEBS polymer having haloalkyl substituents on at least a portion of the styrene of the SEBS polymer).

[0059] Next, the deacylated SEBS polymer is dissolved into an organic solvent in a stirred container. The quaternary ammonium or phosphonium compound or the nitrogen-containing heterocycle is added quickly. The solution is stirred over about 1 to 48 hours at 0 to 100°C. The resulting viscous solution is added dropwise into ethanol to form a solid. The solid is washed with ether and dried completely under vacuum to form the SEBS block copolymer.

[0060] Then, the SEBS block copolymer can be subjected to anion exchange, for example in 1 M KOH for hydroxide exchange, at about 20 to 100 °C for about 12 to 48 hours, followed by washing and immersion in Dl water for about 12 to 48 hours under an oxygen-free atmosphere to remove residual KOH to form the anion- exchanged SEBS block copolymer.

[0061] The norbornene-pyrrolidinium random or block copolymers can be prepared by a method which comprises reacting the norbornene, the

haloalkylnorbornene or a combination thereof in the presence of an organic solvent and a polymerization catalyst to form a norbornene polymer; and reacting the norbornene polymer with the secondary amine or the nitrogen-containing heterocycle in the presence of an organic solvent to form the norbornene-pyrrolidinium random or block copolymer. Then, the norbornene-pyrrolidinium random or block copolymer can be reacted with a base to form the anion-exchanged norbornene-pyrrolidinium random or block copolymer.

[0062]The haloalkylnorbornene can be prepared by a method which comprises reacting maleic anhydride with cyclopentadiene in the presence of an organic solvent to form nadic anhydride; reacting nadic anhydride with a reducing agent (such as lithium aluminium hydride) in the presence of an organic solvent to form 4,5- di(hydroxylmethyl)norbornene; and reacting the 4,5-di(hydroxylmethyl) norbornene with a halide salt (such as phosphorus tribromide) to form the haloalkylnorbornene. The reaction scheme is depicted below:

 [0063]The secondary amine has the formula H N R15R16 wherein R15 and R16 are each independently alkyl, such as lower alkyl.

[0064]The norbornene polymer comprises structural units of formulae 6 and 7A.

[0065]The structural unit having formula 7A has the structure:

wherein X is a halide.

[0066] For example, the norbornene or haloalkylnorbornene monomer such as 4,5-di(dibromomethyl)norbornene can be placed in a stirred container and dissolved or dispersed into an organic solvent such as anhydrous tetrahydrofuran under nitrogen. A polymerization catalyst such as Grubbs' catalyst (second generation) is added quickly at -78 to 60 °C. Thereafter, the reaction is continued at this temperature for about 1 to about 120 hours with stirring. The resulting solution is added dropwise to ethanol. The product obtained is filtered, washed with ethanol and dried completely under vacuum to form the norbornene polymer.

[0067] Next, the norbornene polymer is dissolved into an organic solvent such as chloroform in a stirred container. The quaternary ammonium compound or the nitrogen-containing heterocycle (such as piperidine) is added dropwise. The solution is stirred over about 1 to 48 hours at 0 to 100°C. To the resulting solution is added a reductant (such as p-Tos-HNNhb) and refluxed for 12 to 48 hours. The polymer solution is added dropwise into ethanol. The solid is filtered, washed and dried completely under vacuum to form the norbornene-pyrrolidinium random or block copolymer.

[0068] Then, the norbornene-pyrrolidinium random or block copolymer can be subjected to anion exchange, for example in 1 M KOH for hydroxide exchange, at about 20 to 100 °C for about 12 to 48 hours, followed by washing and immersion in Dl water for about 12 to 48 hours under an oxygen-free atmosphere to remove residual KOH and form the anion-exchanged norbornene-pyrrolidinium random or block copolymer.

[0069] Another aspect of the invention provides a hydroxide exchange polymer comprising a poly(norbornene-pyrrolidinium) backbone free of ether linkages or a styrene-ethylene-butylene-styrene (SEBS) backbone free of ether linkages, and having water uptake not more than 150% based on the dry weight of the polymer when immersed in pure water at room temperature, or having hydroxide conductivity in pure water at room temperature of at least 20 mS/cm, wherein at least one of the following: the polymer is stable to degradation (as evidenced by no change in conductivity) when immersed in 1 M potassium hydroxide at 80 °C for 500 hours; or

the polymer has a tensile strength of at least 40 MPa and/or elongation at break of at least 100%; or

the polymer has a tensile strength of at least 60 MPa and/or elongation at break of at least 150%.

[0070] Yet another aspect of the invention provides hydroxide exchange polymer comprising a poly(norbornene-pyrrolidinium) backbone free of ether linkages or a styrene-ethylene-butylene-styrene (SEBS) backbone free of ether linkages, and having: a peak power density of at least 160 mW/cm² when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at 20% as an hydroxide exchange ionomer in cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a 50% Pt/C catalyst and catalyst loading of 0.4 mg Pt/cm², and test conditions being hydrogen and oxygen flow rates of 0.6 LJmin, no back pressure, cell temperature of 60 °C, and anode and cathode humidifiers at 65 °C and 65 °C, respectively; or

a decrease in voltage over 5.5 hours of operation of not more than 20% and an increase in resistance over 5.5 hours of operation of not more than 20% when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at 20% as an hydroxide exchange ionomer in cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a 50% Pt/C catalyst and catalyst loading of 0.4 mg Pt/cm², and test conditions being constant current density of 400 mA/cm², hydrogen and oxygen flow rates of 0.6 L/min, no back pressure, cell temperature of 60 °C, and anode and cathode humidifiers at 65 °C and 65 °C, respectively.

For example, the peak power density can be at least 200 or 400 mW/cm² for the hydroxide exchange polymer described herein.

For the hydroxide exchange polymers described herein, a decrease in voltage over 60 hours of operation can be not more than 20% and an increase in resistance over 60 hours of operation can be not more than 20% when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at 20% as an hydroxide exchange ionomer in cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a 50% Pt/C catalyst and catalyst loading of 0.4 mg Pt/cm², and test conditions being constant current density of 200 mA/cm², hydrogen and oxygen flow rates of 0.6 L/min, no back pressure, cell temperature of 60 °C, and anode and cathode humidifiers at 65 °C and 65 °C, respectively.

The pyrrolidinium linkages can comprise hydroxide, bicarbonate, or carbonate anions, or a combination thereof

The pyrrolidinium linkages can be derived from a norbornene polymer and a secondary amine or a nitrogen-containing heterocycle as described herein.

[0071]Any of the random or block copolymers as described herein can be made into anion exchange membranes such as hydroxide exchange membranes. Such hydroxide exchange polymer membranes can be prepared by any of the preparation methods described herein by dissolving the random or block copolymer in a solvent and casting the polymer solution to form a polymer membrane before exchanging anions of the polymer membrane with hydroxide ions to form the hydroxide exchange polymer membrane.

[0072] Any of the random or block copolymers as described herein can be made into reinforced hydroxide exchange membranes as described below. Such reinforced hydroxide exchange membranes can be prepared by a method which comprises wetting a porous substrate in a liquid to form a wetted substrate; dissolving the functionalized polymer in a solvent to form a homogeneous solution; applying the solution onto the wetted substrate to form the reinforced membrane; drying the reinforced membrane; and exchanging anions of the reinforced membrane with hydroxide ions to form the reinforced hydroxide exchange polymer membrane. The solution can be applied to the wetted substrate by any known membrane formation technique such as casting, spraying, or doctor knifing.

[0073]The resulting reinforced membrane can be impregnated with the random or block polymer multiple times if desired by wetting the reinforced membrane again and repeating the dissolving, casting and drying steps.

[0074] The polymerization catalyst used in the methods as described herein can comprise trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoro-1- propanesulfonic acid, trifluoroacetic acid, perfluoropropionic acid, heptafluorobutyric acid, or a combination thereof.

[0075] Each of the organic solvents used in the above methods can be independently selected from polar aprotic solvents (e.g., dimethyl sulfoxide, 1 -methyl-2- pyrrolidinone, 1 -methyl-2-pyrrolidone, 1 -methyl-2-pyrrolidone, or dimethylformamide) or other suitable solvents including, but are not limited to, methylene chloride,

trifluoroacetic acid, trifluoromethanesulfonic acid, chloroform, 1 , 1 ,2,2-tetrachloroethane, dimethylacetamide or a combination thereof.

[0076]The solvent in the dissolving step can comprise methanol, ethanol, n- propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, a pentanol, a hexanol, dimethyl sulfoxide, 1 -methyl-2pyrrolidone, dimethylformamide, chloroform, ethyl lactate, tetrahydrofuran, 2-methyltetrahydrofuran, water, phenol, acetone, or a combination thereof.

[0077] The liquid used to wet the porous substrate can be a low boiling point solvent such as a lower alcohol (e.g., methanol, ethanol, propanol, isopropanol) and/or water. Preferably, the liquid is anhydrous ethanol.

[0078]An anion exchange membrane such as a hydroxide exchange membrane is also provided. The membrane is configured and sized to be suitable for use in a fuel cell and comprises any of the random or block copolymers as described herein.

[0079]A reinforced electrolyte membrane such as a reinforced hydroxide exchange membrane is also provided to increase the mechanical robustness of the anion exchange membrane for stability through numerous wet and dry cycles (relative humidity cycling) in a fuel cell. The membrane is configured and sized to be suitable for use in a fuel cell, and comprises a porous substrate impregnated with any of the random or block copolymers as described herein. Methods for preparing reinforced membranes are well known to those of ordinary skill in the art such as those disclosed in U.S. Patent Nos. RE37.656 and RE37.701 , which are incorporated herein by reference for their description of reinforced membrane synthesis and materials.

[0080]The porous substrate can comprise a membrane comprised of polytetrafluoroethylene, polypropylene, polyethylene, poly(ether ketone),

polyaryletherketone, poly(aryl piperidinium), poly(aryl piperidine), polysulfone, perfluoroalkoxyalkane, or a fluorinated ethylene propylene polymer, or other porous polymers known in the art such as the dimensionally stable membrane from Giner for use in preparing reinforced membranes for fuel cells. Such porous substrates are commercially available, for example, from W.L. Gore & Associates.

[0081] The porous substrate can have a porous microstructure of polymeric fibrils. Such substrates comprised of polytetrafluoroethylene are commercially available. The porous substrate can comprise a microstructure of nodes interconnected by fibrils.

[0082]The interior volume of the porous substrate can be rendered substantially occlusive by impregnation with the random or block copolymer.

[0083] The porous substrate can have a thickness from about 1 micron to about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100 microns. Preferably, the porous substrate has a thickness from about 5 microns to about 30 microns, or from about 7 microns to about 20 microns.

[0084]An anion exchange membrane fuel cell is also provided which comprises any of the random or block copolymers as described herein.

[0085]The functionalized polymers can be used in HEMFCs such as a typical fuel cell 10 as shown in Figure 1. Figure 1 illustrates a typical fuel cell 10 with an anode portion 12 (illustrated on the left) and a cathode portion 14 (illustrated on the right) which are separated by an electrolyte membrane 16. The electrolyte membrane 16 can be any membrane comprising any of the random or block copolymers as described herein, and can be a reinforced membrane. Supporting members are not illustrated. The anode portion carries out an anode half-reaction which oxidizes fuel releasing electrons to an external circuit and producing oxidized products. The cathode portion carries out a cathode half-reaction which reduces an oxidizer consuming electrons from the external circuit. The gas diffusion layers (GDLs) 18 and 20 serve to deliver the fuel 22 and oxidizer 24 uniformly across the respective catalyst layers 26 and 28. Charge neutrality is maintained by a flow of ions from the anode to the cathode for positive ions and from cathode to anode for negative ions. The dimensions illustrated are not representative, as the electrolyte membrane is usually selected to be as thin as possible while maintaining the membrane's structural integrity.

[0086] In the case of the illustrated hydroxide exchange membrane fuel cell (HEMFC), the anode half-reaction consumes fuel and OH^" ions and produces waste water (as well as carbon dioxide in the case of carbon containing fuels). The cathode half reaction consumes oxygen and produces OH^" ions, which flow from the cathode to the anode through the electrolyte membrane. Fuels are limited only by the oxidizing ability of the anode catalyst and typically include hydrogen gas, methanol, ethanol, ethylene glycol, and glycerol. Preferably, the fuel is H₂ or methanol. Catalysts are usually platinum (Pt), silver (Ag), or one or more transition metals, e.g., Ni. In the case of a PEMFC, the anode half-reaction consumes fuel and produces H⁺ ions and electrons. The cathode half reaction consumes oxygen, H⁺ ions, and electrons and produces waste water, and H⁺ ions (protons) flow from the anode to the cathode through the electrolyte membrane.

[0087] It can, therefore, be appreciated how an electrolyte membrane made from a random or block copolymer as described herein significantly improves fuel cell performance. First, greater fuel cell efficiency requires low internal resistance, and therefore, electrolyte membranes with greater ionic conductivity (decreased ionic resistance) are preferred. Second, greater power requires greater fuel cell currents, and therefore, electrolyte membranes with greater ion-current carrying capacity are preferred. Also, practical electrolyte membranes resist chemical degradation and are mechanically stable in a fuel cell environment, and also should be readily

manufactured.

[0088] Although a principal application for the random or block copolymers is for energy conversion such as in use in anion exchange membranes, hydroxide exchange membranes, anion exchange membrane fuel cells, and hydroxide exchange membrane fuel cells, the anion/hydroxide exchange ionomers and membranes can be used for many other purposes such as use in fuel cells (e.g., hydrogen/alcohol/ammonia fuel cells); electrolyzers (e.g., water/carbon dioxide/ammonia electrolyzers), electrodialyzers; ion-exchangers; solar hydrogen generators; desalinators (e.g., desalination of sea/brackish water); demineralization of water; ultra-pure water production; waste water treatment; concentration of electrolyte solutions in the food, drug, chemical, and biotechnology fields; electrolysis (e.g., chlor-alkali production and H2/02 production); energy storage (e.g., super capacitors, metal air batteries and redox flow batteries); sensors (e.g. , pH/RH sensors); and in other applications where an anion-conductive ionomer is advantageous.

[0089] Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.

EXAMPLES

[0090]The following non-limiting examples are provided to further illustrate the present invention.

EXAMPLE 1

[0091]A low Tg thermoplastic HEM/HEI was prepared from a commercial triblock polymer known as styrene ethylene butylene styrene (SEBS) and a long side chain quaternary ammonium cation. SEBS-C6QN was prepared by four major steps: (1 ) Friedel-Crafts acylation of SEBS (SEBS-COCsBr), (2) reduction of acylated SEBS (SEBS-CeBr), (3) membrane casting and amination of SEBS-C6Br with trimethylamine (SEBS-C6QN), and (4) hydroxide ion exchange. The reaction scheme is depicted below:

32 1 . NMe₃

2. Base

Γ0092Κ1 ) Synthesis of SEBS-COCsBr polymer. To a 1000 mL three-necked flask equipped with overhead mechanical stirrer, SEBS (10 g) and 6-bromohexanoyl chloride (10 g) were dissolved into methylene chloride (500 mL). Aluminium chloride (5.5 g) was then added slowly at -20 °C. Thereafter, the reaction was continued at this temperature for 2 h. The resulting viscous solution was poured slowly into ethanol. The white fibrous product was filtered, washed with water and ethanol, and then dried completely at 40 °C under vacuum. The yield of the polymer was 95%. ¹ H NMR (CDC , δ, ppm): (see Figure 2).

[0093] (2) Synthesis of SEBS-CeBr polymer. To a 500 mL one-necked flask equipped with magnetic bar, SEBS-COCsBr (5.0 g) was dissolved into methylene chloride (250 mL). Trifluoroacetic acid (50 mL) and triethylsilane (20 mL) was added quickly. The solution was stirred over 12 h at 60 °C. The resulting viscous solution was added dropwise into ethanol. The white fibrous product was filtered, washed with ethanol and dried completely at 40 °C under vacuum. The yield of the polymer was 98%. ¹H NMR (CDC , δ, ppm): 7.08-6.35 (Ar-H), 3.38 (-CH₂Br), 2.51 (Ar-CH₂-), 1.84- 1 .33 (-CH₂-, sidechain), 1 .25-1 .21 (-CH2-, -CH-, backbone), 0.84-0.81 (-CH3, backbone), (see Figure 3). [0094] (3) Preparation of SEBS-C6QN membrane. Membrane was prepared by dissolving the SEBS-C6Br polymer (1.0 g) in toluene (20 ml_) by casting on a clear glass plate at 80 °C for 8 h. The membrane was peeled off from the glass plate and soaked in 45% trimethylamine aqueous solution at room temperature for 24 h. The membrane in hydroxide form were obtained by ion exchange in 1 M KOH at room temperature for 24 h, followed by washing and immersion in Dl water for 48 h under Ar to remove residual KOH.

[0095] SEBS-CeQN membrane was stable in 1 M KOH at 80 °C for 500 h.

SEBS-C6QN membrane at room temperature showed 98% water uptake, 13% swelling ratio and 30 mS/cm hydroxide conductivity in water. SEBS-C6QN membrane was insoluble in methylene chloride, chloroform, toluene, tetrahydrofuran, acetone, ethyl ether, ethanol, methanol, 2-propanol, hexanes, dimethyl sulfoxide, N-Methyl-2- pyrrolidone, dimethylformamide, or water.

[0096] (4) Hydroxide exchange membrane fuel cell (HEMFC) performance. An hydroxide exchange polymer comprising SEBS-C6QN membrane, and having: a peak power density of at least 160 mW/cm² when the SEBS-C6QN is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and AS- 4 commercial ionomer is loaded at 20% as an hydroxide exchange ionomer in cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a 50% Pt/C catalyst and catalyst loading of 0.4 mg Pt/cm², and test conditions being hydrogen and oxygen flow rates of 0.6 L/min, no back pressure, cell temperature of 60 °C, and anode and cathode humidifiers at 65 °C and 65 °C, respectively. See Figure 4.

EXAMPLE 2

[0097]Another example of a low Tg thermoplastic HEM/HEI is based on SEBS and long side chain quaternary imidazolium cation. Briefly, SEBS-C6IM was prepared by four major steps: (1 ) Friedel-Crafts acylation of SEBS (SEBS-COCsBr), (2) reduction of acylated SEBS (SEBS-CeBr), (3) amination of SEBS-CeBr with 1 -butyl-2-mesityl-4,5- dimethyl-1 H-imidazole (SEBS-C6IM), and (4) membrane casting and hydroxide ion exchange. The reaction scheme for preparing the polymer is as follows:

[0098] (1 ) Synthesis of SEBS-COCsBr polymer. SEBS-COCsBr polymer was prepared by Friedel-Crafts acylation of SEBS as in Example 1 .

[0099] (2) Synthesis of SEBS-CeBr polymer. SEBS-CeBr polymer was prepared by reduction of acylated SEBS as in Example 1 .

[00100] (3) Synthesis of 1 -butyl-2-mesityl-4,5-dimethyl-1 H-imidazole. To a mixture of mesitaldehyde (19.25 g, 129.9 mmol) and ammonium acetate (50.13 g, 650.0 mmol) in 300 ml methanol was added a solution of 2, 3-butanedione (1 1 .19 g, 129.9 mmol) in 50 ml methanol dropwise via an additional funnel within 1 hour. The reaction was stirred at room temperature for 7 days and then the solvent was removed. The residue was partitioned between saturated aqueous NaHC03 solution and methylene chloride. The organic phase was removed under vacuum and the solid residue was washed with hot diethyl ether. The solid was filtrated, collected and dried under vacuum affording a white fine powder of 2-mesityl-4,5-dimethyl-1 H-imidazole as the product (15.1 g, 54.2%). H NMR (400 MHz, CDCI3), δ (ppm) = 2.10 (6H, s), 2.20 (6H, s), 2.23 (3H, s), 6.87 (2H, s).

[00101] To a suspension of 4,5-dimethyl-2-(2,4,6-trimethylphenyl) imidazole (1 1.6 g, 54.1 mmol) in dry THF (150 ml) was added lithium hydride (1 .30 g, 54.2 mmol) in three equal portions under nitrogen flow at 0 °C. The mixture was stirred at 0 °C for 30 min and then stirred at room temperature for 1 hour. Then the mixture was cooled to 0 °C and 1 -iodobutane (10.0 g, 54.3 mmol) was charged to the reaction mixture under nitrogen. The reaction was stirred at room temperature for 18 hours and then the mixture was diluted with ether and washed by brine. The organic phase was dried over anhydrous Na2S04 and the solvent was removed under vacuum affording a viscous brown liquid of 1 -butyl-2-mesityl-4,5-dimethyl-1 H-imidazole as the product (13.1 g, 89.7%). H NMR (400 MHz, CDCI3), δ (ppm) = 0.79 (3H, t, J = 4 Hz), 1.15- 1 .19 (2H, m), 1 .40- 1 .42 (2H, m), 2.01 (6H, s), 2.18 (3H, s), 2.20 (3H, s), 2.30 (3H, s), 3.47 (2H, t, J = 4 Hz), 6.87 (2H, s).

[00102] (4) Synthesis of SEBS-Cel M. SEBS-C6-I M membrane was prepared by dissolving the SEBS-C6Br polymer (1.0 g) in toluene (20 mL) by casting on a clear glass plate at 80 °C for 8 h. The membrane was peeled off from the glass plate and refluxed with 1 g of 1-butyl-2-mesityl-4,5-dimethyl-1 H-imidazole in THF for 24 h. The membrane in hydroxide form was obtained by ion exchange in 1 M KOH at room temperature for 24 h, followed by washing and immersion in Dl water for 48 h under Ar to remove residual KOH.

[00103] (5) SEBS-C6I M membrane casting and hydroxide exchange.

Membrane was prepared by dissolving the SEBS-C6IM polymer (1.0 g) in NMP (20 mL) by casting on a clear glass plate at 80 °C for 8 h. The membrane (in bromide form) was peeled off from the glass plate in contact with deionized (Dl) water. The membrane in hydroxide form were obtained by ion exchange in 1 M KOH at room temperature for 24 h, followed by washing and immersion in Dl water for 48 h under Ar to remove residual KOH. EXAMPLE 3

[00104] Another low Tg thermoplastic HEM/HEI is based on ring opening metathesis polymerization (ROMP) of norbornene derivatives and quaternization of amine into ammonium cation. Poly-pyrrolidinium-norbornene (PPNB) was synthesized by four major steps: (1 ) ROMP of norbornene (4,5-di(bromomethyl)norbornene, or mixture with norbornene), (2) quaternization of poly-di(bromomethyl)norbornene, (3) C=C double bond reduction and (4) membrane casting and hydroxide ion exchange. The reaction scheme is shown below, wherein step (a) is the preparation of 4,5- di(bromomethyl)norbornene via Diels-Alder reaction, reduction and bromination: a)

UAIH4

b)

R = Me, -(CH₂)_nMe (n = 1-11)

[00105] (1 ) Synthesis of 4,5-di(bromomethyl)norbornene. To a 200 ml_ round bottom flask charged with magnetic bar, maleic anhydride (10 g) were dissolved into ethyl acetate (100 ml_). Freshly distilled cyclopentadiene (8.5 ml_) was then added dropwise at 0 °C. Thereafter, the reaction was continued at room temperature for 24 h. The EtOAc of resulting solution was removed via rotovap and the white crystalline product was filtrated and washed with hexanes. After drying over vacuum, the analytical pure nadic anhydride was collected with 85% yield.

[00106] Nadic anhydride (10.0 g, 61 mmol) was further reduced with LJAIH4 (4.32 g, 122 mmol) in THF (200 ml_) at room temperature (RT) for 5.5 h. After workup and solvent removal gave 4,5-di(hydroxylmethyl)norbornene in 95% yield.

[00107] Bromination was carried out by slowly dropping PBr3 (2.2 ml_) into a THF solution (100 ml_) of 4,5-di(hydroxylmethyl)norbornene (5.4 g) at 0 °C. The reaction was allowed to stir at 0 °C for 4 h after addition. After quenching and washing with water (3 washes of 10 ml_), the organic phase was combined and dried over vacuum to give the 4,5-di(bromomethyl)norbornene monomer in 90% yield.

[00108] (2) Synthesis of PPNB-Br. To an oven-dried 100 ml_ one-necked flask equipped with magnetic bar, 4,5-di(bromomethyl)norbornene (5.6 g) and norbornene (1.9 g) was dissolved into anhydrous THF (100 ml_) under nitrogen protection. Grubbs' catalyst 2^nd generation (34 mg) was added quickly. The solution was stirred over 4 h at RT. The resulting viscous solution was added dropwise into ethanol. The white fibrous product was filtered, washed with ethanol and dried completely at 40 °C under vacuum. The yield of the polymer was 98%.

[00109] (3) Synthesis of PPNB-Pip. To a 50 mL one-necked flask equipped with magnetic bar, PPNB-Br (7.4 g) was dissolved into chloroform (100 mL). A chloroform solution (10 ml) of piperidine (2 mL) was added dropwise. The solution was stirred over 12 h at 40 °C. The resulting viscous, solution was added p-Tos-HNNH₂ (4 g) and refluxed for 24 h. Thereafter, the polymer solution was added dropwise into ethanol. The solid was filtered, washed with ether and dried completely at 60 °C under vacuum. The yield of the polymer PPNB-Pip was 93%.

The other PPNBs can be synthesized in the same fashion by adding corresponding dialkylamine (HNMe₂, HNEt₂, HNPr₂... ).

[00110] (4) PPNB-Pip membrane casting and hydroxide exchange.

Membrane was prepared by dissolving the PPNB-Pip polymer (1 .0 g) in NMP (20 mL) by casting on a clear glass plate at 80 °C for 8 h. The membrane (in iodide form) was peeled off from the glass plate in contact with deionized (Dl) water. The membrane in hydroxide form were obtained by ion exchange in 1 M KOH at room temperature for 24 h, followed by washing and immersion in Dl water for 48 h under Ar to remove residual KOH.

DEFINITIONS

[00111] The term "suitable substituent," as used herein, is intended to mean a chemically acceptable functional group, preferably a moiety that does not negate the activity of the inventive compounds. Such suitable substituents include, but are not limited to halo groups, perfluoroalkyl groups, perfluoroalkoxy groups, alkyl groups, alkenyl groups, alkynyl groups, hydroxy groups, oxo groups, mercapto groups, alkylthio groups, alkoxy groups, aryl or heteroaryl groups, aryloxy or heteroaryloxy groups, aralkyl or heteroaralkyl groups, aralkoxy or heteroaralkoxy groups, HO— (C=0)— groups, heterocylic groups, cycloalkyl groups, amino groups, alkyl - and dialkylamino groups, carbamoyl groups, alkylcarbonyl groups, alkoxycarbonyl groups,

alkylaminocarbonyl groups, dialkylamino carbonyl groups, arylcarbonyl groups, aryloxycarbonyl groups, alkylsulfonyl groups, and arylsulfonyl groups. Those skilled in the art will appreciate that many substituents can be substituted by additional substituents.

[00112] The term "alkyl," as used herein, refers to a linear, branched or cyclic hydrocarbon radical, preferably having 1 to 32 carbon atoms (i.e., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 39, 30, 31 , or 32 carbons), and more preferably having 1 to 18 carbon atoms. Alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, secondary- butyl, and tertiary-butyl. Alkyl groups can be unsubstituted or substituted by one or more suitable substituents.

[00113] The term "alkenyl," as used herein, refers to a straight, branched or cyclic hydrocarbon radical, preferably having 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 39, 30, 31 , or 32 carbons, more preferably having 1 to 18 carbon atoms, and having one or more carbon-carbon double bonds. Alkenyl groups include, but are not limited to, ethenyl, 1 -propenyl, 2-propenyl (allyl), iso-propenyl, 2-methyl-1 -propenyl, 1-butenyl, and 2-butenyl. Alkenyl groups can be unsubstituted or substituted by one or more suitable substituents, as defined above.

[00114] The term "alkynyl," as used herein, refers to a straight, branched or cyclic hydrocarbon radical, preferably having 2, 3, 4, 5, 6, 7, 8, 9, 10, 1 1 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 39, 30, 31 , or 32 carbons, more preferably having 1 to 18 carbon atoms, and having one or more carbon-carbon triple bonds. Alkynyl groups include, but are not limited to, ethynyl, propynyl, and butynyl. Alkynyl groups can be unsubstituted or substituted by one or more suitable

substituents, as defined above.

[00115] The term "aryl" or "ar," as used herein alone or as part of another group (e.g., aralkyl), means monocyclic, bicyclic, or tricyclic aromatic radicals such as phenyl, naphthyl, tetrahydronaphthyl, indanyl and the like; optionally substituted by one or more suitable substituents, preferably 1 to 5 suitable substituents, as defined above. The term "aryl" also includes heteroaryl.

[00116] "Arylalkyl" or "aralkyl" means an aryl group attached to the parent molecule through an alkylene group. The number of carbon atoms in the aryl group and the alkylene group is selected such that there is a total of about 6 to about 18 carbon atoms in the arylalkyl group. A preferred arylalkyl group is benzyl. [00117] The term "cycloalkyl," as used herein, refers to a mono, bicyclic or tricyclic carbocyclic radical (e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclopentenyl, cyclohexenyl, bicyclo[2.2.1 ]heptanyl, bicyclo[3.2.1 ]octanyl and bicyclo[5.2.0]nonanyl, etc.); optionally containing 1 or 2 double bonds. Cycloalkyl groups can be unsubstituted or substituted by one or more suitable substituents, preferably 1 to 5 suitable substituents, as defined above.

[00118] The term "-ene" as used as a suffix as part of another group denotes a bivalent radical in which a hydrogen atom is removed from each of two terminal carbons of the group, or if the group is cyclic, from each of two different carbon atoms in the ring. For example, alkylene denotes a bivalent alkyl group such as ethylene (- CH2CH2-) or isopropylene (-CH2(CH3)CH2-). For clarity, addition of the -ene suffix is not intended to alter the definition of the principal word other than denoting a bivalent radical. Thus, continuing the example above, alkylene denotes an optionally

substituted linear saturated bivalent hydrocarbon radical.

[00119] The term "ether" as used herein represents a bivalent (i.e.,

difunctional) group including at least one ether linkage (i.e., -0-).

[00120] The term "heteroaryl," as used herein, refers to a monocyclic, bicyclic, or tricyclic aromatic heterocyclic group containing one or more heteroatoms (e.g. , 1 to 3 heteroatoms) selected from O, S and N in the ring(s). Heteroaryl groups include, but are not limited to, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, thienyl, furyl, imidazolyl, pyrrolyl, oxazolyl (e.g., 1 ,3-oxazolyl, 1 ,2-oxazolyl), thiazolyl (e.g. , 1 ,2-thiazolyl, 1 ,3- thiazolyl), pyrazolyl, tetrazolyl, triazolyl (e.g. , 1 ,2,3-triazolyl, 1 ,2,4-triazolyl), oxadiazolyl (e.g., 1 ,2,3-oxadiazolyl), thiadiazolyl (e.g., 1 ,3,4-thiadiazolyl), quinolyl, isoquinolyl, benzothienyl, benzofuryl, and indolyl. Heteroaryl groups can be unsubstituted or substituted by one or more suitable substituents, preferably 1 to 5 suitable substituents, as defined above.The term "hydrocarbon" as used herein describes a compound or radical consisting exclusively of the elements carbon and hydrogen.

[00121] The term "substituted" means that in the group in question, at least one hydrogen atom bound to a carbon atom is replaced with one or more substituent groups such as hydroxy (-OH), alkylthio, phosphino, amido (-CON(RA)(RB), wherein RA and RB are independently hydrogen, alkyl, or aryl), amino(-N(RA)(RB), wherein RA and RB are independently hydrogen, alkyl, or aryl), halo (fluoro, chloro, bromo, or iodo), silyl, nitro (-N02), an ether (-ORA wherein RA is alkyl or aryl), an ester (-OC(O)RA wherein RA is alkyl or aryl), keto (-C(O)RA wherein RA is alkyl or aryl), heterocyclo, and the like. When the term "substituted" introduces or follows a list of possible substituted groups, it is intended that the term apply to every member of that group. That is, the phrase "optionally substituted alkyl or aryl" is to be interpreted as "optionally substituted alkyl or optionally substituted aryl." Likewise, the phrase "alkyl or aryl optionally substituted with fluoride" is to be interpreted as "alkyl optionally substituted with fluoride or aryl optionally substituted with fluoride."

[00122] When introducing elements of the present invention or the preferred embodiments(s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. The terms "comprising", "including" and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[00123] In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

[00124] As various changes could be made in the above products and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

WHAT IS CLAIMED IS:

1 . An anion exchange polymer comprising either:

(a) a styrene-ethylene-butylene-styrene (SEBS) block copolymer of the structure A-B-A, wherein each A is independently a polystyrene-containing block comprising structural units of Formulae 1 and 2 or Formulae 1 and 3, and B is a polyalkylene block comprising polyethylene structural unit 4 and polybutylene structural unit 5, wherein the the structures:

wherein:

Ri , R6 and R7 are each independently alkylene;

R2, R3, R4, and R5 are each independently alkyl, alkenyl, aryl, or alkynyl;

q is O, 1 , 2, 3, 4, 5, or 6;

m, n, xi and X2 are each independently mole fractions of from about 0.01 to about 0.99;

X^" is an anion; and

Z is N or P; or (b) a norbornene-pyrrolidinium random or block copolymer comprising structural units of Formulae 6 and 7 or Formulae 6 and 8, wherein Formulae 6, 7 and 8 have the structure:

wherein:

p is 1 , 2, 3, 4, 5, 6, 7 or 8;

Ri2 and R13 are each independently halide, alkyl, alkenyl, alkynyl or aryl and the alkyl, alkenyl, alkynyl or aryl are optionally substituted with halide; and

X^" is an anion.

The anion exchange polymer of claim 1 , comprising the SEBS block copolym

3. The anion exchange polymer of claim 2, wherein the ratio of the mole fraction of the structural units of Formulae 1 and 2 or Formulae 1 and 3 in the polymer to the mole fraction of the structural unit of Formulae 4 and 5 in the polymer is from about 0.01 to about 1 .

4. The anion exchange polymer of any one of claims 1 -3, wherein at least one of the following:

in the structural unit of formula 2, one of the following:

Ri and R6 are each independently C1-C22 alkylene, R2, R3, R₄, and R5 are each independently C1-C6 alkyl, q is 0, 1 , 2, 3, 4, 5, or 6, X2 is from about 0.01 to about 0.99, and Z is N or P; or

Ri and R6 are each independently C1-C6 alkylene, R2, R3, R₄, and R5 are each independently C1-C6 alkyl, q is 0, 1 , 2, or 3, X2 is from about 0.01 to about 0.99, and Z is N or P; or

Ri and R6 are each independently C8-C22 alkylene; R2, R3, R₄, and R5 are each independently C1-C6 alkyl; q is 0, 1 , 2, or 3, X2 is from about 0.01 to about 0.99, and Z is N or P; or

Ri and R6 are each independently C2-C6 alkylene, R2, R3, R₄, and R5 are methyl, q is 1 , X2 is from about 0.1 1 to about 0.99, and Z is N; or

Ri and R6 are n-hexylene, R2, R3, R₄, and R5 are methyl, q is 1 , X2 is from about 0.01 to about 0.99, and Z is N; and/or

in the structural unit of formula 3, one of the following:

R7 is C1-C22 alkylene, X2 is from about 0.01 to about 0.99, and the nitrogen-containing heterocycle D comprises a fully substituted pyrrole, pyrroline, pyrazole, pyrazoline, imidazole, imidazoline, triazole, pyridine, triazine, pyrazine, pyridazine, pyrimidine, azepine, or quinoline, wherein each substituent is independently alkyl or aryl; or

R7 is C1-C6 alkylene, X2 is from about 0.01 to about 0.99, and the nitrogen-containing heterocycle D comprises an imidazole having the formula:

wherein Rs, R9, R10, and Rn are each independently optionally substituted alkyl, alkenyl, alkynyl, or aryl; or

R7 is C7-C22 alkylene, X2 is from about 0.01 to about 0.99, and the nitrogen-containing heterocycle D comprises the imidazole of formula 10 wherein Rs, R9, and R10 are each independently C1 -C6 alkyl, and Rn is 2,4,6-alkylphenyl; or

R7 is n-hexylene, x₂ is from about 0.01 to about 0.99, and the nitrogen- containing heterocycle D comprises 1-butyl-2-mesityl-4,5-dimethyl-1 /-/-imidazole which has the formula

5. The anion exchange polymer of any one of claims 1 -3, wherein: in the structural unit of formula 2, one of the following:

Ri and R6 are each independently C1-C22 alkylene, R2, R3, R₄, and R5 are each independently C1-C6 alkyl, q is 0, 1 , 2, 3, 4, 5, or 6, X2 is from about 0.01 to about 0.99, and Z is N or P; or Ri and R6 are each independently C1-C6 alkylene, R2, R3, R4, and R5 are each independently C1-C6 alkyl, q is 0, 1 , 2, or 3, x₂ is from about 0.01 to about 0.99, and Z is N or P; or

Ri and R6 are each independently C8-C22 alkylene; R2, R3, R4, and R5 are each independently C1-C6 alkyl; q is 0, 1 , 2, or 3, X2 is from about 0.01 to about 0.99, and Z is N or P; or

Ri and R6 are each independently C2-C6 alkylene, R2, R3, R4, and R5 are methyl, q is 1 , X2 is from about 0.01 to about 0.99, and Z is N; or

Ri and R6 are n-hexylene, R2, R3, R4, and R5 are methyl, q is 1 , X2 is from about 0.01 to about 0.99, and Z is N.

6. The anion exchange polymer of any one of claims 1 -3, wherein:

in the structural unit of formula 3, one of the following:

R7 is C1-C22 alkylene , X2 is from about 0.01 to about 0.99, and the nitrogen-containing heterocycle D comprises a fully substituted pyrrole, pyrroline, pyrazole, pyrazoline, imidazole, imidazoline, triazole, pyridine, triazine, pyrazine, pyridazine, pyrimidine, azepine, or quinoline, wherein each substituent is independently alkyl or aryl;

R7 is C1-C6 alkylene X2 is from about 0.01 to about 0.99, and the nitrogen-containing heterocycle D comprises an imidazole having the formula:

wherein Rs, R9, R10, and Rn are each independently optionally substituted alkyl, alkenyl, alkynyl, or aryl.

R7 is C7-C22 alkylene, X2 is from about 0.01 to about 0.99, and the nitrogen-containing heterocycle D comprises the imidazole of formula 10 wherein Rs, R9, and R10 are each independently C1 -C6 alkyl, and Rn is 2,4,6-alkylphenyl; Px7 is n-hexylene, x₂ is from about 0.01 to about 0.99, and the nitrogen- containing heterocycle D comprises 1-butyl-2-mesityl-4,5-dimethyl-1 /-/-imidazole which has the formula

7. The anion exchange polymer of any one of claims 1 -6, wherein if the

polystyrene-containing block comprises structural units of Formulae 1 and 2, then at least one of the following: Z is P; at least one of R3, R₄ and R5 is not methyl; or Ri is not branched C₄-Ci₄ alkylene.

8. The anion exchange polymer of claim 1 , comprising the norbornene- pyrrolidinium random or block copolymer of (b).

9. The anion exchange polymer of claim 8, wherein the ratio of the mole fraction of the structural unit of Formula 7 or 8 to the mole fraction of the structural unit of Formula 6 in the anion exchange polymer is from about 0.01 to 1 .

10. The anion exchange polymer of any one of claims 1 , 8 and 9, wherein at least one of the following:

in the structural unit of formula 7, one of the following:

R12 and Ri3 are each independently C1-C22 alkyl; or R12 and Ri3 are each independently C1-C6 alkyl; or

R12 and Ri3 are each independently C8-C22 alkyl; or Ri2 and R13 are n-hexyl;

R12 and Ri 3 are methyl; and/or

in the structural unit of formula 8, p is 1 , 2 or 3; and/or

in the structural unit of formula 7 or 8, one of the following:

X- comprises a halide, BF₄ ^", PF6^~, CO3^2" or HCO3-; or

X- comprises a halide, CO3^2" or HCO3-.

1 1. A method of making the SEBS block copolymer of any one of claims 1 -4, the method comprising:

reacting an acylating agent and an SEBS polymer in the presence of an organic solvent and a polymerization catalyst to form an acylated SEBS polymer;

reacting the acylated SEBS polymer and a deacylating agent in the presence of an organic solvent to form a deacylated SEBS polymer; and

reacting the deacylated SEBS polymer and either a quaternary ammonium or phosphonium compound or the nitrogen-containing heterocycle in the presence of an organic solvent to form the SEBS block copolymer,

wherein:

the quaternary ammonium or phosphonium compound has the formula:

the SEBS polymer comprises the structural units of Formulae 1 , 4 and 5;

the acylated SEBS polymer comprises the structural units of Formulae 1 , 2A, 4 and 5;

the deacylated SEBS polymer comprises the structural units of Formulae 1 , 2B, 4 and 5; and

the formulae 2A and 2B have the structure:

wherein Ri₄ is alkylene, and X is an anion.

The method of claim 1 1 , wherein at least one of the following:

the acylating agent comprises an acyl halide; and/or

the deacylating agent comprises triethylsilane, hydrogen, hydrazine, enylsilane, aluminium nickel alloy, or dimethylmonochlorosilane; and/or the SEBS polymer has the formula:

and the acylated SEBS polymer has the formula:

and the deacylated SEBS polymer having the formula:

wherein:

Ri4 is alkylene;

m, n, xi , X2, y, zi and z₂ are each independently a mole fraction from about 0.01 to about 0.99; and

X^" is an anion.

13. A method of making the norbornene-pyrrolidinium random or block copolymer of any one of claims 1 and 8-10, comprising:

reacting norbornene, a haloalkylnorbornene, or a combination thereof in the presence of an organic solvent and a polymerization catalyst to form a norbornene polymer; and

reacting the norbornene polymer with a secondary amine or a nitrogen- containing heterocycle in the presence of an organic solvent to form the norbornene- pyrrolidinium random or block copolymer,

wherein:

the secondary amine has the formula H N R15R16 wherein R15 and R16 are each independently alkyl;

the norbornene polymer comprises structural units of formulae 6 and 7A; and the structural unit having formula 7A has the structure:

wherein X is a halide.

14. The method of any one of claims 1 1 -13, wherein the polymerization catalyst comprises tnfluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoro-1 - propanesulfonic acid, trifluoroacetic acid, perfluoropropionic acid, heptafluorobutyric acid, or a combination thereof.

15. The method of any one of claims 1 1 -14, wherein each of the organic solvents independently comprises dimethyl sulfoxide, 1 -methyl-2-pyrrolidinone, 1 -methyl-2- pyrrolidone, dimethylformamide, methylene chloride, trifluoroacetic acid,

tnfluoromethanesulfonic acid, chloroform, 1 , 1 ,2,2-tetrachloroethane,

dimethylacetamide, or a combination thereof.

16. An hydroxide exchange polymer comprising a poly(norbornene-pyrrolidinium) backbone free of ether linkages or a styrene-ethylene-butylene-styrene (SEBS) backbone free of ether linkages, and having water uptake not more than 150% based on the dry weight of the polymer when immersed in pure water at room temperature, or having hydroxide conductivity in pure water at room temperature of at least 20 mS/cm, wherein at least one of the following:

the polymer is stable to degradation (as evidenced by no change in conductivity) when immersed in 1 M potassium hydroxide at 80 °C for 500 hours; or

17. The polymer of claim 16 wherein the polymer is stable to degradation (as evidenced by no change in conductivity) when immersed in 1 M potassium hydroxide at 80 °C for 500 hours.

18. The polymer of claim 16 or 17, wherein the polymer has a tensile strength of at least 40 MPa and/or elongation at break of at least 100%.

19. The polymer of claim 16 or 17, wherein the polymer has a tensile strength of at least 60 MPa and/or elongation at break of at least 150%.

20. An hydroxide exchange polymer comprising a poly(norbornene-pyrrolidinium) backbone free of ether linkages or a styrene-ethylene-butylene-styrene (SEBS) backbone free of ether linkages, and having:

a peak power density of at least 160 mW/cm² when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at 20% as an hydroxide exchange ionomer in cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a 50% Pt/C catalyst and catalyst loading of 0.4 mg Pt/cm², and test conditions being hydrogen and oxygen flow rates of 0.6 LJmin, no back pressure, cell temperature of 60 °C, and anode and cathode humidifiers at 65 °C and 65 °C, respectively; or

21. The polymer of claim 20 wherein either: the peak power density is at least 400 mW/cm²; or

a decrease in voltage over 60 hours of operation is not more than 20% and an increase in resistance over 60 hours of operation is not more than 20% when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at 20% as an hydroxide exchange ionomer in cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a 50% Pt/C catalyst and catalyst loading of 0.4 mg Pt/cm², and test conditions being constant current density of 200 mA/cm², hydrogen and oxygen flow rates of 0.6 L/min, no back pressure, cell temperature of 60 °C, and anode and cathode humidifiers at 65 °C and 65 °C, respectively.

22. The polymer of any one of claims 16-21 , wherein the pyrrolidinium linkages comprise hydroxide, bicarbonate, or carbonate anions, or a combination thereof.

23. The polymer of any one of claims 16-22, wherein the pyrrolidinium linkages are derived from a norbornene polymer and a secondary amine or a nitrogen-containing heterocycle,

wherein:

the norbornene polymer comprises structural units of formulae 6 and 7A; and the structural units having formula 6 and 7A have the structure:

wherein X is a halide.

24. The polymer of any one of claims 16-23, wherein at least one of the following: the peak power density is at least 200 mW/cm²; or

25. The polymer of any one of claims 16-24, wherein the peak power density is at least 400 mW/cm².

26. The polymer of any one of claims 16-24, wherein a decrease in voltage over 60 hours of operation is not more than 20% and an increase in resistance over 60 hours of operation is not more than 20% when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at 20% as an hydroxide exchange ionomer in cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a 50% Pt/C catalyst and catalyst loading of 0.4 mg Pt/cm², and test conditions being constant current density of 200 mA/cm², hydrogen and oxygen flow rates of 0.6 L/min, no back pressure, cell temperature of 60 °C, and anode and cathode humidifiers at 65 °C and 65 °C, respectively.

27. A method of making an anion exchange polymer membrane comprising the anion exchange polymer of any one of claims 1 -10, the method comprising:

dissolving the SEBS block copolymer or the norbornene-pyrrolidinium random or block copolymer in a solvent to form a polymer solution;

casting the polymer solution to form a polymer membrane; and

exchanging anions of the polymer membrane with hydroxide, bicarbonate, or carbonate ions or a combination thereof to form the anion exchange polymer membrane.

28. The method of claim 27, wherein the solvent in the dissolving step comprises methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, a pentanol, a hexanol, dimethyl sulfoxide, 1 -methyl-2-pyrrolidone, dimethylformamide, chloroform, ethyl lactate, tetrahydrofuran, 2-methyltetrahydrofuran, water, phenol, acetone, or a combination thereof.

29. An anion exchange membrane configured and sized to be suitable for use in a fuel cell and comprising the polymer of any one of claims 1 -10 and 16-26.

30. An anion exchange membrane fuel cell comprising the polymer of any one of claims 1 -10 and 16-26.

31. A reinforced electrolyte membrane configured and sized to be suitable for use in a fuel cell, the membrane comprising a porous substrate impregnated with the polymer of any one of claims 1 -10 and 16-26.

32. The membrane of claim 31 , wherein the porous substrate comprises a membrane comprised of polytetrafluoroethylene, polypropylene, polyethylene, poly(ether) ketone, polyaryletherketone, poly(aryl piperidinium), poly(aryl piperidine), polysulfone, perfluoroalkoxyalkane, or a fluorinated ethylene propylene polymer, and the membrane is optionally a dimensionally stable membrane.

33. The membrane of claim 31 or 32, wherein at least one of the following:

the porous substrate has a porous microstructure of polymeric fibrils; or an interior volume of the porous substrate is rendered substantially occlusive by impregnation with the polymer; or

the porous substrate comprises a microstructure of nodes interconnected by fibrils; or

the porous substrate has a thickness from about 1 micron to about 100 microns; or

the membrane is prepared by multiple impregnations of the substrate with the polymer; or

the membrane is prepared by:

wetting the porous substrate in a liquid to form a wetted substrate; dissolving the polymer in a solvent to form a homogeneous solution; applying the solution onto the wetted substrate to form the reinforced membrane; and

drying the membrane.