Patent Description:
Proton exchange membrane fuel cells (PEMFCs) are considered to be clean and efficient power sources. However, the high cost and unsatisfactory durability of catalysts are major barriers for large-scale commercialization of PEMFCs. 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. <NPL>; <NPL>; <NPL>. 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.

The biggest challenge for HEMs/HEIs at present is achieving a high chemical stability at desired operation temperatures of <NUM> or more, and ideally <NUM> or more (e.g., in the presence of nucleophilic hydroxide ions). 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. <NPL>; <NPL>. 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.

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+. 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. 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. <NPL>; <NPL>; <NPL>; <NPL>; <NPL>. 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 IECs and high temperature. <NPL>; <NPL>; <NPL>; <NPL>.

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 <NUM>.

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.

A polymer is provided which comprises a reaction product of a polymerization mixture comprising.

Another polymer is provided according to claim <NUM> which comprises a reaction product of an alkylating agent and the polymer as described above comprising the reaction product of the polymerization mixture comprising the piperidone monomer.

Yet another polymer is provided according to claim <NUM> which comprises a reaction product of a base and either the polymer as described above, or the polymer comprising the reaction product of the polymerization mixture comprising the <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane salt.

An anion exchange polymer is also provided which comprises structural units of Formulae 1A or 2A, 3A, and 4A, wherein the sum of the mole fractions of the structural unit of Formula 1A or 2A and Formulae 4A is equal to the mole fraction of Formulae 3A in the polymer calculated from the amounts of monomers used in a polymerization reaction to form the polymer, and the mole ratio of the structural unit of Formula 1A or 2A to the structural unit of Formula 3A is from <NUM> to <NUM> calculated from the amounts of monomers used in the polymerization reaction, wherein the structural units of Formulae 1A, 2A, 3A and 4A have the structures:
<CHM>
<CHM>
<CHM>
and
<CHM>
wherein:.

A method of making a polymer is provided according to claim <NUM>, the method comprising: reacting the piperidone monomer, the optional <NUM>,<NUM>,<NUM>-trifluoroacetophenone monomer, and the aromatic monomer in the presence of an organic solvent and a polymerization catalyst to form a piperidine-functionalized intermediate polymer; alkylating the piperidine-functionalized intermediate polymer in the presence of an organic solvent to form a piperidinium-functionalized intermediate polymer; and reacting the piperidinium-functionalized intermediate polymer with a base to form the polymer.

A method of making an hydroxide exchange polymer membrane comprising an hydroxide exchange polymer is also provided according to claim <NUM>, the method comprising: reacting the piperidone monomer, the optional <NUM>,<NUM>,<NUM>-trifluoroacetophenone monomer, and the aromatic monomer in the presence of an organic solvent and a polymerization catalyst to form a piperidine-functionalized intermediate polymer; reacting the piperidine-functionalized intermediate polymer with an alkylating agent in the presence of an organic solvent to form a piperidinium-functionalized intermediate polymer; dissolving the piperidinium-functionalized intermediate polymer 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 ions to form the hydroxide exchange polymer membrane.

An anion exchange membrane is provided according to claim <NUM>.

A fuel cell, electrolyzer, electrodialyzer, ion-exchanger, solar hydrogen generator, desalinator, water demineralizer, device for ultra pure water production, waste water treatment system, device for the concentration of electrolyte solutions in the food, drug, chemical and biotechnology fields, electrolysis device, energy storage device, or sensor is provided according to claim <NUM>.

HEMs/HEIs formed from poly(aryl piperidinium) polymers having intrinsic hydroxide conduction channels have been discovered which simultaneously provide improved chemical stability, conductivity, water uptake, mechanical properties, and other attributes relevant to HEM/HEI performance. The poly(aryl piperidinium) polymers have an alkaline-stable cation, piperidinium, introduced into a rigid aromatic polymer backbone free of ether bonds. HEMs/HEIs 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 HEM/HEIs. The inventive HEMFCs exhibit enhanced performance and durability at relatively high temperatures.

A polymer is provided which comprises a reaction product of a polymerization mixture comprising (i) either a piperidone monomer or a <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane salt monomer, (ii) an aromatic monomer, and (iii) optionally, a trifluoroacetophenone monomer, wherein in the case that the polymerization mixture comprises the <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane salt monomer, the polymerization mixture comprises the trifluoroacetophenone monomer. This polymer is referred to herein as a piperidine-functionalized polymer.

The piperidone monomer has the formula:
<CHM>
wherein R<NUM> is alkyl, alkenyl, or alkynyl, and the alkyl, alkenyl or alkynyl are optionally substituted with fluoride. Preferably, R<NUM> is alkyl such as methyl, ethyl, propyl, butyl, pentyl, or hexyl. Preferably, the piperidone monomer comprises N-methyl-<NUM>-piperidone.

The <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane salt monomer has the formula:
<CHM>
wherein X- is an anion. Preferably, X- is a halide such as chloride, fluoride, bromide, or iodide, BF<NUM>-, or PF<NUM>-. Preferably, the <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane salt monomer comprises <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane iodide.

The aromatic monomer has the formula:
<CHM>
wherein: R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, and R<NUM> are each independently hydrogen, alkyl, alkenyl, or alkynyl, and the alkyl, alkenyl or alkynyl are optionally substituted with fluoride; and n is <NUM>, <NUM>, <NUM> or <NUM>. Preferably, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, and R<NUM> are each independently hydrogen, or alkyl optionally substituted with fluoride, such as methyl, ethyl, propyl, butyl, pentyl or hexyl or methyl, ethyl, propyl, butyl, pentyl, or hexyl substituted with fluoride. Preferably, the aromatic monomer comprises biphenyl, para-terphenyl, para-quaterphenyl or benzene.

The trifluoroacetophenone monomer has the formula:
<CHM>
wherein R<NUM>, R<NUM>, R<NUM>, R<NUM>, and R<NUM> are each independently hydrogen, alkyl, alkenyl, or alkynyl, and the alkyl, alkenyl or alkynyl are optionally substituted with fluoride. Preferably, R<NUM>, R<NUM>, R<NUM>, R<NUM>, and R<NUM> are each independently hydrogen, or alkyl optionally substituted with fluoride, such as methyl, ethyl, propyl, butyl, pentyl or hexyl or methyl, ethyl, propyl, butyl, pentyl, or hexyl optionally substituted with fluoride. Preferably, the <NUM>,<NUM>,<NUM>-trifluoroacetophenone monomer comprises <NUM>,<NUM>,<NUM>-trifluoroacetophenone.

A polymer is also provided which comprises a reaction product of an alkylating agent and the polymer comprising the reaction product of the polymerization mixture comprising the piperidone monomer. This polymer is referred to herein as a piperidinium-functionalized polymer.

Another polymer is provided which comprises a reaction product of a base and the piperidinium-functionalized polymer, or the piperidine-functionalized polymer comprising the reaction product of the polymerization mixture comprising the <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane salt. This polymer is referred to herein as a poly(aryl piperidinium) polymer.

Preferably, the base comprises an hydroxide-containing base such as sodium hydroxide or potassium hydroxide.

The poly(aryl piperidinium) polymer can also be an anion exchange polymer which comprises structural units of Formulae 1A or 2A, 3A, and 4A, wherein the sum of the mole fractions of the structural unit of Formula 1A or 2A and Formulae 4A is equal to the mole fraction of Formulae 3A in the polymer calculated from the amounts of monomers used in a polymerization reaction to form the polymer, and the mole ratio of the structural unit of Formula 1A or 2A to the structural unit of Formula 3A is from <NUM> to <NUM> calculated from the amounts of monomers used in the polymerization reaction. The structural units of Formulae 1A, 2A, 3A and 4A have the structures:
<CHM>
<CHM>
<CHM>
and
<CHM>
wherein: R<NUM> are each independently alkyl, alkenyl, or alkynyl, and the alkyl, alkenyl or alkynyl are optionally substituted with fluoride; R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, and R<NUM> are each independently hydrogen, alkyl, alkenyl, or alkynyl, and the alkyl, alkenyl or alkynyl are optionally substituted with fluoride; n is <NUM>, <NUM>, <NUM> or <NUM>; and X- is an anion such as hydroxide.

When the base comprises a hydroxide-containing base, the resulting poly(aryl piperidinium) polymer can be an hydroxide exchange polymer which has water uptake not more than <NUM>% based on the dry weight of the polymer when immersed in pure water at <NUM>, or has hydroxide conductivity in pure water at <NUM> of at least <NUM>/cm. Also, this polymer can be stable to degradation (as evidenced by no change in peak position on its <NUM>H NMR spectra) when immersed in <NUM> potassium hydroxide at <NUM> for <NUM>,<NUM> hours; be insoluble in pure water and isopropanol at <NUM>, but is soluble in a <NUM>/<NUM> mixture by weight of water and isopropanol at <NUM>; and have a tensile strength of at least <NUM> MPa and elongation at break of at least <NUM>%.

When the base comprises a hydroxide-containing base, the resulting poly(aryl piperidinium) polymer can be an hydroxide exchange polymer which has a peak power density of at least <NUM> mW/cm<NUM> when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at <NUM>% as an hydroxide exchange ionomer in the cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a <NUM>% Pt/C catalyst and catalyst loading of <NUM> Pt/cm<NUM>, and test conditions being hydrogen and oxygen flow rates of <NUM>/min, back pressure of <NUM> MPag, and anode and cathode humidifiers at <NUM> and <NUM>, respectively; or has a decrease in voltage over <NUM> hours of operation of not more than <NUM>% and an increase in resistance over <NUM> hours of operation of not more than <NUM>% when the polymer is used as an hydroxide exchange membrane of an hydroxide exchange membrane fuel cell and is loaded at <NUM>% as an hydroxide exchange ionomer in the cathodic and anodic catalyst layers of the fuel cell, the fuel cell having a <NUM>% Pt/C catalyst and catalyst loading of <NUM> Pt/cm<NUM>, and test conditions being constant current density of <NUM> mA/cm<NUM>, hydrogen and oxygen flow rates of <NUM>/min, back pressure of <NUM> MPag, and anode and cathode humidifiers at <NUM> and <NUM>, respectively.

The piperidine-functionalized polymer can be prepared by a method which comprises reacting the piperidone monomer, the optional <NUM>,<NUM>,<NUM>-trifluoroacetophenone monomer, and the aromatic monomer in the presence of an organic solvent and a polymerization catalyst.

The piperidinium-functionalized polymer can be prepared by a method which comprises alkylating the piperidine-functionalized polymer in the presence of an organic solvent.

The poly(aryl piperidinium) polymers can be prepared by a method which comprises reacting the piperidone monomer, the optional <NUM>,<NUM>,<NUM>-trifluoroacetophenone monomer, and the aromatic monomer in the presence of an organic solvent and a polymerization catalyst to form a piperidine-functionalized intermediate polymer; alkylating the piperidine-functionalized intermediate polymer in the presence of an organic solvent to form a piperidinium-functionalized intermediate polymer; and reacting the piperidinium-functionalized intermediate polymer with a base to form the poly(aryl piperidinium) polymer.

For example, a piperidone monomer such as N-methyl-<NUM>-piperidone, an optional <NUM>,<NUM>,<NUM>-trifluoroacetophenone monomer such as <NUM>,<NUM>,<NUM>-trifluoroacetophenone, and an aromatic monomer such as benzene, biphenyl, p-terphenyl or p-quaterphenyl can be placed in a stirred container and dissolved into an organic solvent. A polymerization catalyst in a solvent can then be added dropwise over up to <NUM> minutes at -<NUM> to <NUM>. Thereafter, the reaction is continued at this temperature for about <NUM> to about <NUM> hours. The resulting solution is poured slowly into an aqueous solution of ethanol. The solid obtained is filtered, washed with water and immersed in <NUM> K<NUM>CO<NUM> at room temperature for about <NUM> to <NUM> hours. Finally, the product is filtered, washed with water and dried completely under vacuum to form a piperidine-functionalized intermediate polymer.

Next, the piperidine-functionalized polymer is dissolved into an organic solvent in a stirred container. An alkylating agent is added quickly. The solution is stirred over about <NUM> to <NUM> hours at <NUM> to <NUM>. The resulting solution is added dropwise into ether. The resulting solid is filtered, washed with ether and dried completely to form the piperidinium-functionalized polymer.

The piperidinium-functionalized polymer is then subjected to anion exchange, for example in <NUM> KOH for hydroxide exchange, at about <NUM> to <NUM> for about <NUM> to <NUM> hours, followed by washing and immersion in DI water for about <NUM> to <NUM> hours under an oxygen-free atmosphere to remove residual KOH.

When the base comprises a hydroxide-containing base, the resulting poly(aryl piperidinium) polymers can be made into hydroxide exchange membranes. Such hydroxide exchange polymer membranes can be prepared by a method which comprises reacting the piperidone monomer, the optional <NUM>,<NUM>,<NUM>-trifluoroacetophenone monomer, and the aromatic monomer in the presence of an organic solvent and a polymerization catalyst to form a piperidine-functionalized intermediate polymer; reacting the piperidine-functionalized intermediate polymer with an alkylating agent in the presence of an organic solvent to form a piperidinium-functionalized intermediate polymer; dissolving the piperidinium-functionalized intermediate polymer 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 ions to form the hydroxide exchange polymer membrane.

When the base comprises a hydroxide-containing base, the resulting poly(aryl piperidinium) polymers 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 poly(aryl piperidinium) 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.

The resulting reinforced membrane can be impregnated with the poly(aryl piperidinium) polymer multiple times if desired by wetting the reinforced membrane again and repeating the dissolving, casting and drying steps.

The polymerization catalyst used in forming the piperidine-functionalized intermediate polymer can comprise trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, heptafluoro-<NUM>-propanesulfonic acid, trifluoroacetic acid, perfluoropropionic acid, heptafluorobutyric acid, or a combination thereof.

The alkylating agent used in forming the piperidinium-functionalized intermediate polymer can comprise an alkyl halide such as methyl iodide, iodoethane, <NUM>-iodopropane, <NUM>-iodobutane, <NUM>-iodopentane, <NUM>-iodohexane, or a combination thereof.

Each of the organic solvents used in the above methods can be independently selected from polar aprotic solvents (e.g., dimethyl sulfoxide, <NUM>-methyl-<NUM>-pyrrolidinone, or dimethylformamide) or other suitable solvents including, but are not limited to, methylene chloride, trifluoroacetic acid, trifluoromethanesulfonic acid, chloroform, <NUM>,<NUM>,<NUM>,<NUM>-tetrachloroethane, or a combination thereof.

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.

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 poly(aryl piperidinium) polymers as described herein.

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 poly(aryl piperidinium) polymers as described herein. Methods for preparing reinforced membranes are well known to those of ordinary skill in the art such as those disclosed in <CIT> and <CIT>, which describe reinforced membrane synthesis and materials.

The porous substrate can comprise a membrane comprised of polytetrafluoroethylene, polypropylene, polyethylene, poly(ether ketone), 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. Gore & Associates.

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.

The interior volume of the porous substrate can be rendered substantially occlusive by impregnation with the poly(aryl piperidinium) polymer.

The porous substrate can have a thickness from about <NUM> micrometer to about <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM> micrometers. Preferably, the porous substrate has a thickness from about <NUM> micrometers to about <NUM> micrometers, or from about <NUM> micrometers to about <NUM> micrometers.

A fuel cell, electrolyzer, electrodialyzer, ion-exchanger, solar hydrogen generator, desalinator, water demineralizer, device for ultra pure water production, waste water treatment system, device for the concentration of electrolyte solutions in the food, drug, chemical and biotechnology fields, electrolysis device, energy storage device, or sensor is also provided which comprises any of the poly(aryl piperidinium) polymers as described herein.

The poly(aryl piperidinium) polymers can be used in HEMFCs such as a typical fuel cell <NUM> as shown in <FIG> illustrates a typical fuel cell <NUM> with an anode portion <NUM> (illustrated on the left) and a cathode portion <NUM> (illustrated on the right) which are separated by an electrolyte membrane <NUM>. The electrolyte membrane <NUM> can be any membrane comprising any of the poly(aryl piperidinium) polymers 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) <NUM> and <NUM> serve to deliver the fuel <NUM> and oxidizer <NUM> uniformly across the respective catalyst layers <NUM> and <NUM>. 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.

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 H<NUM> or methanol. Catalysts are usually platinum (Pt), gold (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.

It can, therefore, be appreciated how an electrolyte membrane made from a poly(aryl piperidinium) polymer 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.

Although a principal application for the poly(aryl piperidinium) polymers 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 H<NUM>/O<NUM> 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.

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.

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

A poly(aryl piperidinium) was prepared from N-methyl-<NUM>-piperidone, <NUM>,<NUM>,<NUM>-trifluoroacetophenone and biphenyl (referred to as PAP-<NUM>-x, wherein x is the mole ratio of N-methyl-<NUM>-piperidone to <NUM>,<NUM>,<NUM>-trifluoroacetophenone and is from <NUM> to <NUM>). PAP-<NUM>-x was prepared by three major steps: (<NUM>) synthesis of a piperidine-functionalized polymer, (<NUM>) synthesis of a piperidinium-functionalized polymer, and (<NUM>) membrane casting and hydroxide ion exchange. The reaction scheme is depicted below:
<CHM>.

Another example of a poly(aryl piperidinium) is based on N-methyl-<NUM>-piperidone, <NUM>,<NUM>,<NUM>-trifluoroacetophenone and p-terphenyl (PAP-<NUM>-x, x is the mole ratio of N-methyl-<NUM>-piperidone to <NUM>,<NUM>,<NUM>-trifluoroacetophenone, x = <NUM> to <NUM>). The reaction scheme for preparing the polymer is as follows:
<CHM>.

Another poly(aryl piperidinium) polymer is based on N-methyl-<NUM>-piperidone, <NUM>,<NUM>,<NUM>-trifluoroacetophenone and p-quaterphenyl (PAP-<NUM>-x, wherein x is the mole ratio of N-methyl-<NUM>-piperidone to <NUM>,<NUM>,<NUM>-trifluoroacetophenone, x = <NUM> to <NUM>). The synthesis of PAP-<NUM>-x is similar to PAP-<NUM>-x and is shown in the reaction scheme below:
<CHM>.

Another poly(aryl piperidinium) polymer is based on N-methyl-<NUM>-piperidone, <NUM>,<NUM>,<NUM>-trifluoroacetophenone and benzene (PAP-<NUM>-x, x is the mole ratio of N-methyl-<NUM>-piperidone to <NUM>,<NUM>,<NUM>-trifluoroacetophenone, x = <NUM> to <NUM>). The synthesis of PAP-<NUM>-x is similar to PAP-<NUM>-x and the reaction scheme is shown below:
<CHM>.

Another poly(aryl piperidinium) polymer is based on <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane iodide, <NUM>,<NUM>,<NUM>-trifluoroacetophenone, and biphenyl (PAP-ASU-<NUM>-x, x is the mole ratio of <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane iodide and <NUM>,<NUM>,<NUM>-trifluoroacetophenone, x = <NUM> to <NUM>). The reaction scheme for the synthesis is as follows:
<CHM>.

Yet another poly(aryl piperidinium) polymer is based on <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane iodide, <NUM>,<NUM>,<NUM>-trifluoroacetophenone and p-terphenyl (PAP-ASU-<NUM>-x, wherein x is the mole ratio of <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane iodide to <NUM>,<NUM>,<NUM>-trifluoroacetophenone, x = <NUM> to <NUM>). The reaction scheme for the polymer synthesis is shown below:
<CHM>.

Another poly(aryl piperidinium) polymer is based on <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane iodide, <NUM>,<NUM>,<NUM>-trifluoroacetophenone and p-quaterphenyl (PAP-ASU-<NUM>-x, wherein x is the mole ratio of <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane iodide to <NUM>,<NUM>,<NUM>-trifluoroacetophenone, x = <NUM> to <NUM>). The polymer synthesis reaction scheme is shown below:
<CHM>.

Another poly(aryl piperidinium) polymer is based on <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane iodide, <NUM>,<NUM>,<NUM>-trifluoroacetophenone and benzene (PAP-ASU-<NUM>-x, wherein x is the mole ratio of <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane iodide to <NUM>,<NUM>,<NUM>-trifluoroacetophenone, x = <NUM> to <NUM>). The reaction scheme for the polymer synthesis is shown below:
<CHM>.

A reinforced membrane was fabricated by the following procedure. First, <NUM> PAP-<NUM>-<NUM> polymer (prepared according to the method of Example <NUM>) in iodine form was dissolved in <NUM> dimethylformamide solvent (DMF) to form a PAP solution. To improve the wettability of a <NUM> polyethylene (PE) substrate in DMF, the porous PE membrane was soaked in anhydrous ethanol for <NUM>. Meanwhile, <NUM> of ethanol and <NUM> water were added into the PAP solution and stirred for <NUM> to form a homogeneous solution. The homogeneous solution was casted onto the wetted PE membrane to prepare the reinforced membrane. The membrane was heated in an oven at <NUM> for <NUM> to remove the solvent, and the resulting reinforced membrane was further dried in a vacuum at <NUM> for <NUM>. The conversion from I- form to OH- form was achieved by leaving the membrane in <NUM> KOH for <NUM> at <NUM>. The OH-exchanged reinforced PAP/PE membrane was washed with DI water until pH of <NUM> was reached. The conductivity of the reinforced PAP/PE HEM is <NUM>/cm at <NUM> in DI water, with water content up is about <NUM>%. The thickness of the reinforced PAP/PE HEM is about <NUM>.

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=O)-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.

The term "alkyl," as used herein, refers to a linear, branched or cyclic hydrocarbon radical, preferably having <NUM> to <NUM> carbon atoms (i.e., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> carbons), and more preferably having <NUM> to <NUM> 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.

The term "alkenyl," as used herein, refers to a straight, branched or cyclic hydrocarbon radical, preferably having <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> carbons, more preferably having <NUM> to <NUM> carbon atoms, and having one or more carbon-carbon double bonds. Alkenyl groups include, but are not limited to, ethenyl, <NUM>-propenyl, <NUM>-propenyl (allyl), isopropenyl, <NUM>-methyl-<NUM>-propenyl, <NUM>-butenyl, and <NUM>-butenyl. Alkenyl groups can be unsubstituted or substituted by one or more suitable substituents, as defined above.

The term "alkynyl," as used herein, refers to a straight, branched or cyclic hydrocarbon radical, preferably having <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> carbons, more preferably having <NUM> to <NUM> 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.

The term "aryl," as used herein, 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 <NUM> to <NUM> suitable substituents, as defined above. The term "aryl" also includes heteroaryl.

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[<NUM>. <NUM>]heptanyl, bicyclo[<NUM>. <NUM>]octanyl and bicyclo[<NUM>. <NUM>]nonanyl, etc.); optionally containing <NUM> or <NUM> double bonds. Cycloalkyl groups can be unsubstituted or substituted by one or more suitable substituents, preferably <NUM> to <NUM> suitable substituents, as defined above.

The term "ether" as used herein represents a bivalent (i.e., difunctional) group including at least one ether linkage (i.e., -O-).

The term "heteroaryl," as used herein, refers to a monocyclic, bicyclic, or tricyclic aromatic heterocyclic group containing one or more heteroatoms (e.g., <NUM> to <NUM> 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., <NUM>,<NUM>-oxazolyl, <NUM>,<NUM>-oxazolyl), thiazolyl (e.g., <NUM>,<NUM>-thiazolyl, <NUM>,<NUM>-thiazolyl), pyrazolyl, tetrazolyl, triazolyl (e.g., <NUM>,<NUM>,<NUM>-triazolyl, <NUM>,<NUM>,<NUM>-triazolyl), oxadiazolyl (e.g., <NUM>,<NUM>,<NUM>-oxadiazolyl), thiadiazolyl (e.g., <NUM>,<NUM>,<NUM>-thiadiazolyl), quinolyl, isoquinolyl, benzothienyl, benzofuryl, and indolyl. Heteroaryl groups can be unsubstituted or substituted by one or more suitable substituents, preferably <NUM> to <NUM> suitable substituents, as defined above. The term "hydrocarbon" as used herein describes a compound or radical consisting exclusively of the elements carbon and hydrogen.

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 (-NO<NUM>), 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.

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

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. (e.g., <NUM> to <NUM> 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., <NUM>,<NUM>-oxazolyl, <NUM>,<NUM>-oxazolyl), thiazolyl (e.g., <NUM>,<NUM>-thiazolyl, <NUM>,<NUM>-thiazolyl), pyrazolyl, tetrazolyl, triazolyl (e.g., <NUM>,<NUM>,<NUM>-triazolyl, <NUM>,<NUM>,<NUM>-triazolyl), oxadiazolyl (e.g., <NUM>,<NUM>,<NUM>-oxadiazolyl), thiadiazolyl (e.g., <NUM>,<NUM>,<NUM>-thiadiazolyl), quinolyl, isoquinolyl, benzothienyl, benzofuryl, and indolyl. Heteroaryl groups can be unsubstituted or substituted by one or more suitable substituents, preferably <NUM> to <NUM> suitable substituents, as defined above. The term "hydrocarbon" as used herein describes a compound or radical consisting exclusively of the elements carbon and hydrogen.

Claim 1:
A polymer comprising a reaction product of a polymerization mixture comprising
(i) a piperidone monomer having the formula:
<CHM>
or
a <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane salt monomer having the formula:
<CHM>
(ii) an aromatic monomer having the formula:
<CHM>
and
(iii) optionally, a trifluoroacetophenone monomer having the formula:
<CHM>
wherein:
R<NUM> is alkyl, alkenyl, or alkynyl, and the alkyl, alkenyl or alkynyl are optionally substituted with fluoride;
R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, R<NUM>, and R<NUM> are each independently hydrogen, alkyl, alkenyl, or alkynyl, and the alkyl, alkenyl or alkynyl are optionally substituted with fluoride;
n is <NUM>, <NUM>, <NUM> or <NUM>; and
X- is an anion; and
wherein in the case that the polymerization mixture comprises the <NUM>-oxo-<NUM>-azoniaspiro[<NUM>]undecane salt monomer having the formula (<NUM>), the polymerization mixture comprises the trifluoroacetophenone monomer.