Functional polymers and applications

Abstract

The present application relates to a polymer (such as a polymer of intrinsic microporosity). This comprises a polymeric backbone comprising contorted aromatic moieties and at least one side group as defined herein.

Description

[0001] Functional polymers and applications

[0002] Field

[0003] The present disclosure relates to polymers of intrinsic microporosity (PIMs). The present disclosure relates more particularly, but not necessarily exclusively, to PIMs which may be used in ion-exchange membranes, separation membranes for molecular and ion separations, or ion-conducting ionomer binders used in membrane electrode assemblies in electrochemical devices.

[0004] Background

[0005] Ion-conducting polymer membranes are a component in a wide range of separation processes, such as electrodialysis and diffusion dialysis and electrochemical devices for energy conversion and storage, including fuel cells, electrolyzers, and redox flow batteries. In these devices, membranes are a semi- permeable separator isolating anodic and cathodic compartments from one another, while allowing selective transport of small ions for charge balancing during operation. Similarly, ionomers act as catalysts binders in membrane electrode assemblies that stabilize catalysts while facilitating ion transport. Membranes and ionomers that concurrently deliver high ionic conductivity and high charge- and size-based selectivity are desirable to facilitate improvement of efficiency, energy / power density, and lifetime of these low-carbon technologies towards significant cost reduction as required for more widespread deployment.

[0006] However, all existing membranes suffer from the trade-off between conductivity and selectivity for ion transport. At present, most commercial ion-conducting membranes are based on ion exchange polymers comprising ionic groups chemically bonded to their hydrophobic polymer backbones or side chains, such as perfluorosulfonic acid polymers. However, despite their fast ion conduction, selectivity towards ions of different sizes and charge remains unsatisfactory. Moreover, the benchmark membrane material, Nation™, is expensive.

[0007] It is desirable to provide an improved membrane and / or otherwise to obviate and / or mitigate one or more of the disadvantages with known membranes, whether identified herein or otherwise; and / or to provide an alternative.

[0008] Summary

[0009] According to a first aspect, there is provided a polymer of intrinsic microporosity comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising a carboxylic acid and an oxadiazole moiety; wherein the or each side group is attached to the polymeric backbone by said oxadiazole moiety.

[0010] According to a second aspect, there is provided a method of preparing a polymer of intrinsic microporosity comprising

[0011] (a) providing a precursor polymer comprising a polymeric backbone comprising contorted aromatic moieties (optionally as defined in relation to the first aspect); and at least one side group comprising an amidoxime.

[0012] (b) adding the precursor to an anhydride or adding the anhydride to the precursor.

[0013] According to a third aspect, there is provided a polymer of intrinsic microporosity obtained or obtainable by the method of the second aspect.

[0014] According to a fourth aspect, there is provided is an ion-exchange membrane or resin comprising a polymer of intrinsic microporosity according to the first or third aspect. According to a fifth aspect, there is provided is use of a polymer of intrinsic microporosity according the first or third aspect in an ion-exchange membrane or resin.

[0015] According to a sixth aspect, there is provided an ion-exchange membrane comprising a polymer of intrinsic microporosity comprising a backbone comprising contorted aromatic moieties; and at least one side group comprising a phosphonic acid and a perfluorinated phenyl group; wherein the or each side group is attached to the backbone by said perfluorinated phenyl group.

[0016] According to a seventh aspect, there is provided a battery, comprising an anode and a cathode; wherein the anode and cathode are separated by an ion-exchange membrane according to the fourth or sixth aspect of the invention.

[0017] According to an eighth aspect, there is provided a kit of parts for a battery, wherein the kit comprises an anode, a cathode, and an ion-exchange membrane according to the fourth or sixth aspect of the invention.

[0018] According to a ninth aspect, there is provided a polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising wherein R is an aliphatic or aromatic carboxylic acid group; wherein p is from 1 to 100;

[0019] According to a tenth aspect, there is provided a polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising wherein the or each side group is attached to the polymeric backbone; and wherein the polymeric backbone further comprises moiety pendant therefrom (optionally wherein said moiety is between adjacent contorted aromatic moieties), where R1-R5 are optionally substituted by hydrogen, fluoride, and CF3.

[0020] According to an eleventh aspect, there is provided an ion-exchange membrane comprising a polymer according to the ninth or tenth aspect.

[0021] According to a twelfth aspect, there is provided use of an ion-exchange membrane according to the eleventh aspect in electrodialysis.

[0022] According to a thirteenth aspect, there is provided use of an ion-exchange membrane according to the eleventh aspect in a redox flow battery.

[0023] According to a fourteenth aspect, there is provided use of an ion-exchange membrane according to the eleventh aspect in ion separation, such as separation of Li+from Mg2+, e.g. in an aqueous solution thereof.

[0024] According to a fifteenth aspect, there is provided an electrodialysis ion-exchange membrane comprising a polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising C(=NOH)NH2 or COOH.

[0025] According to a sixteenth aspect, there is provided use of a polymer of formula as an electrodialysis ion-exchange membrane.

[0026] According to a seventeenth aspect, there is provided a method of preparing a polymer (such as a polymer of intrinsic microporosity), suitably a polymer according to the ninth or tenth aspect, the method comprising polymerisation of: a monomer A comprising a contorted aromatic moiety CA1; a monomer B comprising a side group Sia or side group precursor SP; to provide a polymer comprising a polymeric backbone comprising contorted aromatic moieties and said at least one side group or side group precursor; optionally wherein the method comprises polymerisation of said monomer B comprising a side group precursor SPand wherein the method further comprises modifying the side group precursor SPof the polymeric backbone to form a side group Sia.

[0027] Description of the Figures

[0028] Figure 1 shows a. synthesis routes and b-c structural characterization including1H NMR (b),13C NMR (c) of the model compound, DABD-SA, prepared following the synthesis routes. Figure 2 shows examples of cPIMs. a. synthetic routes, b-d structural characterization including1H NMR (b),13C NMR (c) and FT-IR (c) spectra. These characterization results confirmed the claimed chemical structures of the polymers.

[0029] Figure 3 shows porosity characterization of cPIMs (Examples 2-4). a. N2 sorption isotherms at 77K, b. CO2 adsorption isotherms at 273K. b Pore size distribution based on DFT calculations of CO2 adsorption isotherms. These results confirm the microporous structure of the polymers.

[0030] Figure 4 shows ion transport properties of cPIMs (Examples 2-4). a. Ionic conductivity in 1 M aqueous KCI. b Upper bound plot for ferro / ferricyanide permeability versus apparent ionic conductivity, showing that the performance of our cPIMs outperform all existing membranes.

[0031] Figure 5 shows cell resistance and power density cell voltage and power density versus current density for redox flow batteries assembled with cPIM-PA, Nation 212 and sPEEK. Catholyte: 6.67 mL mixed solution of 0.75 M K4Fe(CN)e and 0.75 M Na4Fe(CN)e in deionized water at pH 7; anolyte: 5 mL 1 .1 M 2,6-D2PEAQ in mixed supporting electrolyte of 0.5 M KCI and 0.5 M NaCI at pH 7..

[0032] Figure 6 shows cycling stability. Redox flow batteries assembled with cPIM-PA (Example 3) membrane demonstrated stable cycling performance with 10-100 times lower capacity fate rate compared with conventional membranes. Catholyte: 6.67 mL mixed solution of 0.75 M K4Fe(CN)e and 0.75 M Na4Fe(CN)e in deionized water at pH 7; anolyte: 5 mL 1 .1 M 2,6-D2PEAQ in mixed supporting electrolyte of 0.5 M KCI and 0.5 M NaCI at pH 7. Volumetric capacity is based on the total volume of catholyte and anolyte.

[0033] Figure 7 shows porosity and proton conductivity of pPIM-SBI-PFB. a. Photo of a pPIM-SBI-PFB membrane, b.19F NMR spectra of pPIM-SBI-PFB before and after the introduction of phosphoric acid groups, c. N2 adsorption isotherms at 77K. d CO2 adsorption isotherms at 273K. e Proton conductivity of pPIM-SBI-PFB measured in deionised water.

[0034] Figure 8 shows experimental apparatus for electrodialysis tests, (a) The picture of a lab-scale electrodialysis setup for ion separation, (b) The diagram of an electrodialysis (ED) process for monovalent / divalent ion separation.

[0035] Figure 9 shows electrodialysis separation performance of AO-PIM-1 membrane for monovalent / divalent ion separation, (a) Li ion permeation rate and Li / Mg selectivity of AO-PIM-1 for Li / Mg separation under different current densities, (b) K ion permeation rate and K / Mg selectivity of AO-PIM-1 for K / Mg separation under different current densities, (c) Na ion permeation rate and Na / Mg selectivity of AO- PIM-1 for Na / Mg separation under different current densities, (d) Permeation rate of salt ions through AO-PIM-1 as a function of hydrated diameter of ions, (e) Selectivity of monovalent ions over Mg2+ions, (f) Ion permeation rate and selectivity of AO-PIM-1 membrane for separation of mixed ions (KCI, NaCI, LiCI, MgCI2, 0.1 M each).

[0036] Figure 10 shows lithium extraction in a laboratory-scale electrodialysis stack, a, Photos of one piece of AO-PIM-1 membrane and two pieces of AEM membranes, b, Photo of the membrane assembled in the electrodialysis stack, c, Photo of one electrodialysis stack in operation, d, Ion concentration profiles of concentrate chamber, with feed solution of KCI / NaCI / LiCI / MgCh (0.1 M), and derived e, Ion permeation rates and selectivity, f, X-ray diffraction pattern of U2CO3 product. The inset photo shows the purified U2CO3 solid, g, Ion concentration profiles of concentrate chamber, with simulated salt-lake brine solution as feed solution, h, Ion permeation rates and selectivity derived from (g). i, Compositions of initial feed solution and concentrate solution after testing for 8 h.

[0037] Figure 11 shows ion separation performance of ether-free AO-PIM membranes, a, Ion permeation rates of binary salt mixtures for PIM-SBI-OH-AO, PIM-SBI-OMe-AO and PIM-SBI-OMe-CN. b, Monovalent / divalent ion selectivity of PIM-SBI-OH-AO, PIM-SBI-OMe-AO and PIM-SBI-OMe-CN membranes, c, Ion permeation rate and selectivity of PIM-SBI-OH-AO membrane for feed solution of KCI / NaCI / LiCI / MgCL mixtures (0.1 M each).

[0038] Figure 12 shows electrodialysis performance of fluorinated AO-PIM membrane, (a) The concentration of K+and Mg2+in concentrate chamber as a function of time, (b) The concentration of Na+and Mg2+in concentrate chamber as a function of time, (c) The concentration of Li+and Mg2+in concentrate chamber as a function of time, (d) Permeation rate and selectivity of SBI-OH-5F-AO for ion separation.

[0039] Figure 13 shows electrodialysis separation performance of EO-functionalized PIM membranes, (a) The concentration of Li+and Mg2+in concentrate chamber as a function of time, (b) The concentration of Mg2+in concentrate chamber as a function of time, (c) Permeation rate and selectivity of the four membranes for Li+and Mg2+separation.

[0040] Figure 14 shows electrodialysis separation performance of carboxylic acid-functionalized PIM membranes, (a) The concentration of Li+and Mg2+in concentrate chamber as a function of time for cPIM-1 membrane, (b) The concentration of Li+and Mg2+in concentrate chamber as a function of time for cPIM-1-0Me membrane., (c) Li ion permeation rate and Li / Mg selectivity of cPIM-1 and cPIM-OMe.

[0041] Figure 15 shows properties of ether-free AO-PIM membranes, (a) Ion conductivity in 1 M KOH. (b) KOH permeation through the membrane, (c) Crossover profiles of K4Fe(CN)e.

[0042] Figure 16 shows performance of ether-free AO-PIM membranes in organic flow batteries, (a) Membrane resistance, (b) Polarization curve with state-of-charge (SOC) at 20%, 50%, and 100%.

[0043] Figure 17 shows anion exchange membrane properties, (a) Hydroxide conductivity as a function of temperature, (b) Water uptake as a function of temperature, (c) Swelling ratio as a function of temperature.

[0044] Figure 18 shows correlation between ion conductivity and hydration number as a function of comonomer content, (a) Hydroxide conductivity, (b) Hydration number.

[0045] Figure 19 shows AEM electrolyser performance, (a) Comparison of AEM membranes with different backbone structures, (b) Comparison of AEM membranes with different contorted monomer content at 80°C. (c) Comparison of AEM membranes with different thickness at 80°C. (d) Comparison of AEM membranes with different concentration of KOH, membrane thickness was 15 pm. (e) Long-term durability tests of PAP-15BzMA-TP membrane. Test condition: Anode: 2 mg / cm2RuO2 with 10% ionomer (commercial PAP-BP-60) Cathode: 0.7 mg / cm2Pt Ru / C with 25% ionomer (commercial PAP- BP-60) AEM: Homemade PAP-15BzMA-TP 60 pm. Electrolyte solution in most cases: 1 M KOH.

[0046] Definitions

[0047] Unless otherwise defined herein, terms have their usual meaning, e.g. as defined in the IUPAC Compendium of Chemical Terminology (2019), version 3.0.1 , informally known as the "Gold Book".

[0048] The following definitions apply for terms used herein.

[0049] The term “at least one” is synonymous with “one or more”, i.e. one, two, three, four, five, six, or more.

[0050] As used herein the term “about” generally encompasses or refers to a range of values that one skilled in the art would consider equivalent to the recited values (i.e. having substantially the same function or result and / or achieving those in the same way). Where the term “about” is used in relation to a numerical value, it can represent (in increasing order of preference) a 10%, 5%, 2%, 1 % or 0% deviation from that value.

[0051] The term “monomer” or “repeating unit” is one of the art. For the avoidance of any doubt, monomers are molecules that can be bonded to other molecules to form a polymer or a copolymer comprising units of the monomer.

[0052] The term “polymer” as used herein may refer to a molecule comprising two or more (such as three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, or ten or more) monomer units. A polymer may comprise many monomer units, such as 100 or more monomer units (which may be denoted using subscripts, e.g. “n”).

[0053] The term “copolymer” is one of the art. It refers to a polymer comprising two or more different monomers that are polymerised in a process known as copolymerisation. The term “polymer of intrinsic microporosity” (PIM) refers to a class of microporous polymer which is characterized by a large volume of interconnected pores which are less than 2 nm in diameter. The pore size is typically measured using gas adsorption technology, for example using the Brunauer- Emmett-Teller (BET) method or the Barrett-Joyner-Halenda (BJH) method.

[0054] Gas sorption is a standard technique for characterizing porosity and pore size distribution in PIMs, following methods. The porosity and pore size distribution may be determined according to industrial standard ISO 15901-2:2022(en). Molecular simulation and positron annihilation lifetime spectroscopy (PALS) may also be used to support gas sorption results. The Apparent BET surface area of PIMs is typically in the range of from 100 to 2000 m2g-1and preferably in the range of from 400 to 1000 m2g-1.

[0055] The term “polymeric backbone” is one of the art. For the avoidance of any doubt, the backbone of a polymer is the main chain of a polymer from which other chains, long or short or both, depend. The main chain may be understood as being the highest molecular weight linear chain (continuous chain) of the polymer.

[0056] The term “chain” is one of the art. Polymer chains can exhibit various configurations, including linear, branched, or cross-linked structures, depending on the type of polymerization process and the presence of branching agents, cross-linking agents, etc. during polymerisation and post-polymerization modifications.

[0057] In some examples, microporosity may be provided with polymeric backbones having substantially restricted or prohibited rotation in conjunction with the polymeric backbone comprising contorted aromatic moieties. Substantially restricted or prohibited rotation may be achieved through the use of fused ring structures, cross-linked / network / framework structures or backbones with steric hinderance. Here, rotation of constituent moieties making up the polymeric backbone are substantially restricted or prohibited from rotation around the main chain of the polymeric backbone. In general terms, this may be understood as restricting or prohibiting conformation changes that would otherwise allow the constituent moieties of the polymer backbone (particularly the contorted aromatic moieties) to pack efficiently.

[0058] The degree of steric hindrance is typically characterized by dihedral angle analysis, in which there is a significant energy barrier to overcome for the dihedral angle between the two planar rings to change.

[0059] The term “contorted aromatic” (otherwise known as contorted polycyclic aromatic hydrocarbon) refers to a polycyclic aromatic hydrocarbon (PAH, having at least two rings) which is unable to adopt a planar configuration. The planarity of the aromatic rings may be disrupted by the introduction of bulky moieties with steric hindrance, the presence of one or more spiro moieties, bridged moieties or the presence of non-planar fused rings in the contorted aromatic. The introduction of one or more of these prevent the aromatic ring system from aligning in a planar arrangement. As a result, the aromatic ring(s) adopt a non-planar, contorted conformation. The resultant conformation of the contorted aromatic compound may be helical, twisted (e.g. when spiro moieties are present) or otherwise have bulky protrusions (e.g. non-planar fused rings, bridges or pendant bulky moieties with steric hindrance) extending outside of a plane of the remainder of the aromatic group.

[0060] The term “side group” or “pendant group” is also one of the art. These refer to moieties attached to or hanging from the backbone main chain of a polymer.

[0061] The term “aromatic” moiety, ring or group refers to a cyclic moiety (i.e. in the shape of a ring). An aromatic is an unsaturated monocyclic or polycyclic ring system obeying Huckel’s rule, having from 5 to 20 carbon atoms. An aromatic group is optionally a “Ce-14 aromatic group” and is an aromatic group constituted by 6, 7, 8, 9, 10, 11 , 12, 13 or 14 carbon atoms and includes condensed ring groups such as monocyclic ring group, or bicyclic ring group and the like.

[0062] As used herein, “groups connected by a spiro system” means that the chemical groups mentioned are joined by a spiro moiety, having one single common atom connecting two rings. For example, the wording “at least two aromatic rings are connected a spiro system” refers to a spiro system (having two rings with only one common atom connecting the two rings) connecting the at least two aromatic rings. For example, the at least two aromatic rings may be connected by spiro [4.4] nonane to which the aromatic groups may be fused.

[0063] The term “linker” as used herein may refer to at least one bond or group that links two moieties together. For example, as used herein, the term linker refers to at least one bond or group that links moieties present in the backbone together.

[0064] The term “moiety” as used herein refers to a distinct and identifiable part within a compound, polymer, reagent, etc. A compound or reagent comprising a moiety may consist of the moiety. For example, if an anhydride comprises the following moiety: , then the anhydride may be (consist of) oxolane-2, 5-dione (also known as succinic anhydride). Alternatively, the moiety may represent a specific fragment or substructure (e.g. of a polymer of a larger compound). In such cases, the moiety may be attached to the remainder (e.g. of the polymer or larger compound) at any available position understood from the drawn structure as bearing a hydrogen atom, unless the positioning of attachment is otherwise represented herein using “wavy” bonds, black dots (•) or asterisks (*). The moiety may be attached at multiple positions (e.g. to form fused rings).

[0065] Thus the term “linker moiety” is used herein to refer to a group that links the contorted aromatic moieties so as to form the polymeric backbone. Therefore on the linker moiety there may be a single bond attaching to the contorted aromatic moiety, or two or more bonds from the linker moiety attaching to the contorted aromatic moiety in multiple locations. This may be represented herein by a single and dashed bond as follows: - (comprising one bond of attachment, two bonds, or more). A linker moiety may comprise, for example, several carbon atoms (e.g. it may be a ring, e.g. cyclopentane). In such instances, where there are multiple points of attachment denoted using the single and dashed bond notation, it will be appreciated that two bonds could extend from one carbon atom (e.g. there may be a double bond) and this may restrict / prevent rotation in the polymeric backbone as described above. Alternatively or additionally, a bond may extend from one carbon atom and another bond may extend from another carbon atom. These carbon atoms may be understood as framework atoms which make up the main structure of the linker moiety. Thus, the single and dashed bonds may be understood as denoting one or more points of attachment to the framework atoms of the linker moiety. Similar comments apply if heteroatoms are present in the linker moiety.

[0066] For example, in the following structure: where the contorted aromatic moiety is:

[0067] The linker moiety is: which attaches to the contorted aromatic moiety in four locations, two on each side.

[0068] The term “oxadiazole moiety” is used herein to refer to a five-membered heterocyclic ring containing two nitrogen atoms and one oxygen atom in the ring. Examples of oxadiazoles include 1 ,2,3-oxadiazole, 1 ,2,4-oxadiazole, 1 ,2,5-oxadiazole and 1 ,3,4-oxadiazole.

[0069] As used herein, the term “anhydride” means to refer to a compound that contains two acyl groups (independently having the formula R-C=O) bonded to the same oxygen atom. A “cyclic anhydride” is formed when the R groups are linked and thereby form a ring structure comprising the oxygen atom and the two R groups. Cyclic anhydrides can have different ring sizes (e.g. 5, 6, 7, 8 or more ring atoms, including the oxygen thereof). The R groups may be the same or different. Examples of cyclic anhydrides include succinic anhydride, phthalic anhydride and maleic anhydride. Other anhydrides are defined elsewhere herein.

[0070] An aliphatic group contains carbon chains that may be straight or branched, and may contain single, double, or triple bonds between carbon atoms. Aliphatic groups can be saturated, consisting of only single bonds, or unsaturated, containing one or more multiple bonds (e.g. double bonds).

[0071] A heteroaromatic group is an aromatic group having, in addition to carbon atoms, at least one (e.g. from one to four, e.g. 1 , 2, 3 or 4) ring heteroatoms which are optionally each independently selected from O, S, N, P and Si (or combinations thereof).

[0072] The term “alkyl” refers to an optionally substituted saturated hydrocarbon group (having carbon and hydrogen atoms). It may be straight-chain or branched, and the number of carbon atoms can vary. Examples include methyl, ethyl, propyl, butyl, and the like. Suitable chain lengths include, for example, C1-20 alkyl, or C1-15 alkyl, such as C1-10 alkyl.

[0073] The term “alkenyl” refers to an unsaturated hydrocarbon group that contains at least one carbon-carbon double bond. It may be straight-chain or branched, and the number of carbon atoms can vary. Examples include vinyl, allyl, butenyl, and the like. Suitable chain lengths include, for example, C1-20 alkenyl, or Ci- 15 alkenyl, such as C1-10 alkenyl.

[0074] The term “aryl” refers to a aromatic moiety (as defined above), such as benzene. It has a cyclic structure containing conjugated double bonds. Examples include phenyl, naphthyl, and the like.

[0075] The term “haloalkyl” refers to an alkyl group in which one or more of the hydrogen atoms is replaced by a halogen atom(s). Examples of halogens include fluorine, chlorine, bromine, iodine, etc. Examples of haloalkyl groups include chloromethyl, bromoethyl, trifluoromethyl, and the like. Suitable chain lengths include, for example, C1-20 haloalkyl, or C1-15 haloalkyl, such as C1-10 haloalkyl.

[0076] The term “haloaryl” refers to an aryl group in which one or more of the hydrogen atoms is replaced by a halogen atom. Examples of halogens include fluorine, chlorine, bromine, and iodine. Examples of haloaryl groups include chlorophenyl, bromonaphthyl, trifluoromethylphenyl, and the like.

[0077] The term “alkoxy” refers to an alkyl group attached to an oxygen atom. It may be straight-chain or branched, and the number of carbon atoms can vary. Examples include methoxy, ethoxy, propoxy, and the like. Suitable chain lengths include, for example, C1-20 alkoxy, or C1-15 alkoxy, such as C1-10 alkoxy.

[0078] The term “carboxylic acid” refers to compounds containing of a carboxyl functional group (-COOH). Carboxylic acids can be either aliphatic or aromatic in nature. The carboxyl group can attract and interact with positively charged ions (e.g. present in an electrolyte, aqueous or nonaqueous, surrounding a polymer of intrinsic microporosity). The oxygen atoms in the carboxyl group have lone pairs of electrons, which can form electrostatic interactions with cations, such as alkali metal ions (e.g., Na+, K+, Li+, Ca2+, Zn2+, Mg2+and AP+)

[0079] The term “phosphonic acid” refers to compounds containing of a phosphonic acid functional group (- PO(OH)2). Phosphonic acids can be either aliphatic or aromatic in nature. The phosphonic acid functional group can attract and interact with positively charged ions (e.g. present in an electrolyte, aqueous or nonaqueous, surrounding a polymer of intrinsic microporosity). The oxygen atoms in the phosphonic acid functional group have lone pairs of electrons, which can form electrostatic interactions with cations, such as alkali metal ions (e.g., Na+, K+, Li+, Ca2+,Zn2+, Mg2+and Al3+)

[0080] Whenever a group is described as being "optionally substituted", that group may be unsubstituted or substituted with one or more substituents individually and independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl, heterocyclyl, aryl(alkyl), heteroaryl(alkyl), heterocyclyl(alkyl) and halogen.

[0081] The phrasing “comprises a [named] group” is used herein to mean that it comprises the named moiety, and optionally other moieties. For example, “comprises a phenyl moiety ” is used herein to mean that a phenyl moiety is present but further moieties can also be present.

[0082] Detailed Description

[0083] According to a first aspect, there is provided a polymer of intrinsic microporosity comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising a carboxylic acid and an oxadiazole moiety; wherein the or each side group is attached to the polymeric backbone by said oxadiazole moiety.

[0084] It has been found that, when used in ion-exchange membranes or resins, the polymers disclosed herein show excellent properties in relation to transport of protons and small cations, whilst prohibiting crossover of the large ions and molecules. The ion-exchange membranes claimed herein outperform other membranes (such as Nation™ membranes) in terms of the trade-off between ionic conductivity and selectivity, providing opportunities to improve device performance particularly energy and power density, and device lifetime. It has been found that ion-exchange membranes or resins as disclosed herein may significantly reduce the overall cost of aqueous batteries whilst improving the lifetime and power output.

[0085] Suitably, each contorted aromatic moiety comprises a ring system with at least two aromatic rings, for example at least three aromatic rings, such as at least four aromatic rings or at least five aromatic rings, optionally wherein the ring system includes one or more heteroatoms, such as nitrogen.

[0086] For example, the at least two aromatic rings may be phenyl rings, for example at least three phenyl rings, such as at least four phenyl rings or at least five phenyl rings, which may optionally include one or more heteroatoms, such as nitrogen.

[0087] Suitably, each contorted aromatic moiety may comprise about 10 to 100 carbon atoms, optionally about 10 to 75 carbon atoms, optionally about 10 to 50 carbon atoms.

[0088] Suitably, the at least two aromatic rings may be connected by:

[0089] (a) a spiro system;

[0090] (b) a fused ring system;

[0091] (c) a bridged ring system; or

[0092] (d) a single bond and / or a double bond; or a combination thereof.

[0093] Suitably, the at least two aromatic rings may be connected by a spiro system as follows, which may be optionally substituted:

[0094] Suitably, the at least two aromatic rings are connected by a fused ring system, wherein the fused ring system comprises one ring fused to said at least two aromatic rings, such as an optionally substituted cyclopentane.

[0095] Suitably, the at least two aromatic rings may be connected by a bridged ring system, wherein the bridged ring system is carbocyclic, such as one of the following, which may be optionally substituted: or heterocyclic (e.g. heterocyclic equivalents of the aforementioned carbocyclic rings, comprising one or more heteroatoms), optionally comprising one or more (e.g. two) nitrogen atoms, such as the following, which may be optionally substituted: optionally wherein the bridged ring system is fused to said at least two aromatic rings.

[0096] Suitably, each contorted aromatic moiety may be independently selected from the following, which may be optionally substituted: w eren te oc otsn cate poss e attacment pontsn te poymerc ac one. For example, each contorted aromatic moiety may be optionally substituted: wherein R 1, R2, R3 and R4 are eachnepenenty seecte rom hydrogen, C1-10 alkyl, C1-10alkenyl or C6-14 aryl, optionally wherein R1, R2, R3 and R4 are each independently selected from H, CH3 or tert-butyl; or optionally wherein R1 and R2 and / or R3 and R4 are taken, together with the intervening atoms to which they are attached, to independently form a ring (e.g. a 6 membered ring, optionally aromatic, optionally fused to one or more additional rings which are optionally aromatic), optionally wherein R1and R2and / or R3and R4are taken, together with the intervening atoms to which they are attached, to independently form (i.e., to form benzene) and / or

[0097] For example, each contorted aromatic moiety may be optionally substituted:

[0098] (cCA5’) wherein R5 and Re are each independently hydrogen or C1-3 alkyl, optionally CH3.

[0099] For example, each contorted aromatic moiety may be optionally substituted: wherein R7 and Ra are each independently selected from hydrogen or C1-10 haloalkyl, optionally fluoroalkyl such as (CF2)nCF3 wherein n is from 1 to 9, such as 1 , 3, 5 or 7; or wherein R7 and Re are taken, together with the intervening atoms to which they are attached, to form a perfluorinated ring, optionally a six membered ring,

[0100] E F

[0101] F, V F

[0102] F~T r

[0103] F-CH HC--FF optionally wherein R7and R8are taken together to form

[0104] For example, each contorted aromatic moiety may be optionally substituted: (cCA7’) wherein R9, R10, R11 and R12 are each independently selected from hydrogen, fluorine, phenyl, C1-15 alkyl, C1-15 haloalkyl, C1-15 alkenyl or C1-15 haloalkenyl; optionally wherein R9 and R10 are each independently selected from hydrogen or fluorine, or optionally wherein R9 and R10 are taken, together with the intervening atoms to which they are attached, to form optionally substituted with one or more electron withdrawing groups, such as a trihalogenated methyl group, e.g. CF3 groups, such as optionally wherein Rn and R12 are each independently selected from hydrogen, fluorine, phenyl or C1-5 alkyl, such as methyl, ethyl or isopropyl; optionally wherein Rn and R12 are both the same.

[0105] For example, each contorted aromatic moiety may be optionally substituted:

[0106] (cCA8’) wherein Rn and R14 are each independently selected from hydrogen, C1-10 alkyl or C1-10 haloalkyl, optionally wherein R13 and R14 are each independently selected from hydrogen or (CH2)n(CH3) wherein n is from 1 to 9, for example 1 , 3, 5 or 7, optionally substituted with one or more fluoro atoms, for example (CF2)nCF3 wherein n is from 1 to 9, for example 1 , 5 or 7; optionally wherein R13 and R14 are the same or wherein R13 and R14 are taken together to form

[0107] For example, each contorted aromatic moiety may be optionally substituted:

[0108] (cCA1 T) wherein R15, R16, R17 and Ria are each independently selected from hydrogen or C1-10 alkyl, such as C1- 5 alkyl, for example methyl, ethyl or isopropyl. optionally wherein R15, R16, R17 and Ria are the same.

[0109] Suitably, contorted aromatic moieties may be linked by a linker moiety to form the backbone.

[0110] Suitably, the backbone may be adapted to prevent free rotation of each contorted aromatic moiety relative to said backbone, optionally wherein the linker moiety is adapted to prevent free rotation of each contorted aromatic moiety relative to the said backbone (e.g. wherein the linker moiety bonds to at least two locations on each contorted aromatic moiety).

[0111] Suitably, the or each side group is attached by the oxadiazole moiety to:

[0112] (a) the or each contorted aromatic moiety; or (b) the linker moiety.

[0113] Suitably, the or each side group is attached by the oxadiazole moiety to:

[0114] (a) polymer comprising a polyethylene backbone, such as polyacrylonitrile, a polyamidoxime or a residue thereof, or (b) a covalent organic framework.

[0115] Suitably, the polymer is of formula: wherein:

[0116] CA is said contorted aromatic moiety,

[0117] Li is said linker moiety, each Si or S2 is independently said side group or hydrogen, nitrile, amine, amide, carboxylic acid or amidoxime; with the proviso that at least one of Si and S2 is said side group, and n is at least 2 (optionally at least 100).

[0118] R

[0119] Suitably, each Si or S2 may be independently , or hydrogen, nitrile, amine, amide, carboxylic acid or amidoxime; and wherein R is an aliphatic or aromatic carboxylic acid group.

[0120] Suitably, Li may comprise an optionally substituted phenyl group.

[0121] For example, Li may be optionally substituted:

[0122] For example, the polymer may be of formula:

[0123] Suitably, the or each R is independently:

[0124] (a) a monocarboxylic acid of formula Y-COOH, wherein Y is an alkyl (optionally interrupted by one or more oxygen atoms), haloalkyl (optionally a fluoroalkyl) or aryl group (such as comprising one phenyl group or two or more phenyl groups); or

[0125] (b) a dicarboxylic acid of formula HOOC-Y’-COOH, wherein Y’ is an aryl group.

[0126] For example, the or each R may be independently selected from: wherein m is 2, 3 or 4 wherein R19, R20, R21 and R22 are each independently H or F

[0127]

[0128] For example, the polymer may be of formula: wherein n is at least 2 (optionally at least 100).

[0129] For example, the polymer may be of formula: wherein n is at least 2 (optionally at least 100).

[0130] For example, the polymer may be of formula: wherein n is at least 2 (optionally at least 100).

[0131] The polymer may comprise a repeat unit of molecular weight of from about 500 to about 1500 g mol’1, such as from about 700 to about 1000 g mol’1.

[0132] The polymers of the present invention may have a molecular weight of from about 1000 g mol-1to about 1000,000 g mol-1, such as from about 10,000 g mol-1to about 500,000 g mol-1, such as from about 100,000 g mol1to 300,000 g mol1. The molecular weight of the polymers may be measured, for example, by Gel Permeation Chromatography (GPC).

[0133] According to a second aspect, there is provided a method of preparing a polymer of intrinsic microporosity comprising

[0134] (a) providing a precursor polymer comprising a polymeric backbone comprising contorted aromatic moieties (optionally as defined in any preceding claim); and at least one side group comprising an amidoxime.

[0135] (b) adding the precursor to an anhydride or adding the anhydride to the precursor.

[0136] Suitably, said adding may be in the presence of an alkali reagent.

[0137] The alkali reagent may be selected from a hydroxide or an ethoxide; optionally a sodium or potassium hydroxide or ethoxide; or mixtures thereof

[0138] Suitably, the anhydride and the alkali reagent are at a molar ratio from about 1 :1 to about 1 :3, such as from about 1 :1 to about 1 :2, or about 1 :2 to about 1 :3, preferably about 1 :2 to about 1 :2.5.

[0139] Suitably, the anhydride and the precursor polymer are provided at a molar ratio of from about 2:1 to about 12:1 , such as from about 2:1 to about 6:1 , or from about 2:1 to about 8:1 , for example about 2:1 to about 10:1 , preferably about 4:1 to about 6:1 .

[0140] The method may further comprise adjusting to a pH of from 1 to 2 after said (b).

[0141] Suitably, the precursor polymer is of formula: wherein CA is a contorted aromatic moiety;

[0142] Li is a linker moiety;

[0143] S3 is hydrogen or said side group and n is at least 2 (optionally at least 100).

[0144] The anhydride is suitably a cyclic anhydride, optionally comprising a ring having at least 5 ring atoms, optionally at least 6 ring atoms, optionally at least 7 ring atoms;, optionally wherein the anhydride comprises one or more moieties of formula , which may be optionally substituted in the ring thereof to replace a carbon with one or more heteroatoms, such as oxygen.

[0145] The anhydride may comprise least one phenyl group, such as two phenyl groups or three phenyl groups, for example four phenyl groups or five phenyl groups (e.g. pendant or fused to the remainder of the anhydride).

[0146] The anhydride may be optionally substituted with one or more halogens, for example fluorine.

[0147] The anhydride may be selected from one of the following, which may be optionally substituted

[0148]

[0149] According to a third aspect, there is provided a polymer of intrinsic microporosity obtained or obtainable by the method disclosed herein.

[0150] According to a fourth aspect, there is provided an ion-exchange membrane comprising said polymer of intrinsic microporosity.

[0151] According to a fifth aspect, there is provided a use of a polymer of intrinsic microporosity disclosed herein in an ion-exchange membrane or resin.

[0152] Methods of preparing such ion-exchange membranes are known in the art. For example, the polymers may be prepared using strip casting.

[0153] For example, polymers may be dissolved in DMSO or NMP to afford a homogeneous solution with polymer concentration in the range of from about 1 to about 20 wt.%, preferably from about 2 to about 8 wt.%.

[0154] The solutions may then be centrifuged at 12,000 rpm for 10 min or filtered through a pad of glass wool to remove impurities. The solutions may then be poured into glass Petri dishes or blade-casted on a glass plate. After the formation of uniform liquid films on glass plates or Petri dishes, the liquid films may be kept in an oven at elevated temperatures (from about 60 to about 120 °C) to allow solvent evaporation for about 24 h. Afterwards, polymer films may be peeled off upon immersion in water and optionally stored in deionised water.

[0155] According to a sixth aspect, there is provided an ion-exchange membrane comprising a polymer of intrinsic microporosity comprising a backbone comprising contorted aromatic moieties; and at least one side group comprising a phosphonic acid and a perfluorinated phenyl group; wherein the or each side group is attached to the backbone by said perfluorinated phenyl group. The polymer may be a copolymer of formula: wherein CA is a contorted aromatic moiety, wherein Si is a side group comprising a perfluorinated phenyl substituted with a phosphonic acid, wherein each of RT, R2 and R3 are independently hydrogen or optionally substituted alkyl, haloalky I, aryl or haloaryl (e.g. optionally wherein the aryl is bicyclic); optionally wherein each R3 is independently a perfluorinated phenyl; wherein m is from 0 to 1000 (preferably from 100 to 500) and wherein n is from 0 to 1000 (preferably from 100 to 500).

[0156] Rr may be hydrogen or a Ci-io haloalkyl group, optionally CF3.

[0157] R2 may be hydrogen or a Ci-io haloalkyl group, optionally CF3.

[0158] R3 may be optionally substituted C1-10 alkyl, C1-10 haloaryl or C6-20 aryl, e.g. perfluorinated phenyl .

[0159] For example, R3 may be selected from optionally substituted:

[0160] Si may be

[0161] Suitably, each contorted aromatic moiety may comprise a ring system with at least two aromatic rings, for example at least three aromatic rings, such as at least four aromatic rings or at least five aromatic rings, optionally wherein the ring system includes one or more heteroatoms.

[0162] For example, the at least two aromatic rings are phenyl rings, for example at least three phenyl rings, such as at least four phenyl rings or at least five phenyl rings.

[0163] Each contorted aromatic moiety may comprise about 10 to 100 carbon atoms, optionally about 10 to 75 carbon atoms, optionally about 10 to 50 carbon atoms.

[0164] Suitably, the at least two aromatic rings are connected by:

[0165] (a) a spiro system;

[0166] (b) a fused ring system;

[0167] (c) a bridged ring system; or

[0168] (d) a single bond and / or double bond. or a combination thereof.

[0169] For example, the at least two aromatic rings may be connected by a spiro system as follows, which may be optionally substituted:

[0170] For example, the at least two aromatic rings may be connected by a fused ring system, wherein the fused ring system comprises one ring fused to said at least two aromatic rings, such as an optionally substituted cyclopentane.

[0171] For example, the at least two aromatic rings may be connected by a bridged ring system, wherein the bridged ring system is carbocyclic, such as one of the following, which may be optionally substituted: or heterocyclic (e.g. heterocyclic equivalents of the aforementioned carbocyclic rings, comprising one or more heteroatoms), optionally comprising one or more nitrogen atoms (e.g. two), such as the following, which may be optionally substituted: optionally wherein the bridged ring system is fused to said at least two aromatic rings.

[0172] Suitably, each contorted aromatic moiety may comprise one of the following, which may be optionally substituted:

[0173] wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0174] For example, each contorted aromatic moiety may be optionally substituted: wherein R1, R2, R3 and R4are each independently selected from hydrogen, C1-10 alkyl, Ci-ioalkenyl or Ce-i4aryl, optionally wherein R1, R2, R3 and R4are each independently selected from: H, CH3 or tert-butyl; or optionally wherein Ri and R2 and / or R3 and R4 are taken, together with the intervening atoms to which they are attached, to independently form a ring (e.g. a 6 membered ring, optionally aromatic, optionally fused to one or more additional rings which are optionally aromatic), optionally wherein R1and R2and / or R3and R4are taken, together with the intervening atoms to which they are attached, to independently form (i.e., to form benzene) and / or wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy

[0175] (preferably OCH3).

[0176] For example, each contorted aromatic moiety may be optionally substituted:

[0177] (pCA5’) wherein R5 and Re are each independently hydrogen or C1-3 alkyl, optionally CH3; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0178] For example, each contorted aromatic moiety may be optionally substituted: wherein R7 and Rs are each independently selected from hydrogen or C1-10 haloalkyl, optionally fluoroalkyl such as (CF2)nCF3 wherein n is from 1 to 9, such as 1 , 3, 5 or 7 or wherein R7 and Rs are taken, together with the intervening atoms to which they are attached, to form a perfluorinated ring, optionally a six membered ring, optionally wherein R7and R8are taken together to form wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3). For example, each contorted aromatic moiety may be optionally substituted: wherein R9, R10, R11 and R12 are each independently selected from hydrogen, fluorine, phenyl, C1-15 alkyl, C1-15 haloalkyl, C1-15 alkenyl or C1-15 haloalkenyl; optionally wherein R9 and R10 are each independently selected from hydrogen or fluorine, or optionally wherein R9 and R10 are taken, together with the intervening atoms to which they are attached, to form optionally substituted with one or more electron withdrawing groups, such as a trihalogenated methyl group, e.g. CF3 groups, such as optionally wherein Rn and R12 are each independently selected from hydrogen, fluorine, phenyl or C1-5 alkyl, such as methyl, ethyl or isopropyl; optionally wherein Rn and R12 are both the same; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0179] For example, each contorted aromatic moiety may be optionally substituted: wherein Rn and R14 are each independently selected from hydrogen, C1-10 alkyl or C1-10 haloalkyl, optionally wherein R13 and R14 are each independently selected from hydrogen or (CH2)n(CH3) wherein n is from 1 to 9, for example 1 , 3, 5 or 7, optionally substituted with one or more fluoro atoms, for example (CF2)nCF3 wherein n is from 1 to 9, for example 1 , 5 or 7; optionally wherein R13 and R14 are the same or wherein R13 and R14 are taken together to form * * wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0180] For example, each contorted aromatic moiety may be optionally substituted: wherein R15, R16, R17 and Ris are each independently selected from hydrogen or C1-10 alkyl, such as Cis alkyl, for example methyl, ethyl or isopropyl. optionally wherein R15, R16, R17 and Ris are the same; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0181] Suitably, contorted aromatic moieties may be linked by a linker moiety to form the backbone.

[0182] Suitably, the backbone may be adapted to prevent free rotation of each contorted aromatic moiety relative to said backbone, optionally the linker moiety may be adapted to prevent free rotation of each contorted aromatic moiety relative to the said backbone (e.g. wherein the linker moiety bonds to at least two locations on each contorted aromatic moiety).

[0183] Suitably, the or each side group is attached by the perfluorinated phenyl group to:

[0184] (a) the or each contorted aromatic moiety; or (b) the linker moiety.

[0185] Suitably, the or each side group is attached by the oxadiazole moiety to:

[0186] (a) polymer comprising a polyethylene backbone, such as polyacrylonitrile, a polyamidoxime or a residue thereof, or (b) a covalent organic framework.

[0187] For example, the linker moiety is a single bond alkoxy.

[0188] For example, the ion-exchange membrane of the sixth aspect may comprise a polymer of formula:

[0189]

[0190] Suitably, the polymer may be obtained by addition of a suitable phosphonated polymer precursor to tri(trimethylsilyl)phosphite or by addition of tri(trimethylsilyl)phosphite to a suitable phosphonated polymer precursor.

[0191] For example, the polymer precursor may be of formula

[0192] The polymer may comprise at least one repeat unit of molecular weight of from about 400 to about 1500 g mol1, such as from about 600 to about 1000 g mol1.

[0193] The polymer may have a molecular weight of from about 1000 g mol1to about 1000,000 g mol1, such as from about 10,000 g mol-1to about 500,000 g mol-1, such as from about 100,000 g mol-1to 300,000 g mol-1. The molecular weight of the polymers may be measured, for example, by Gel Permeation Chromatography (GPC).

[0194] The ion-exchange membranes of the present invention may have an ionic conductivity of from about 5 mS cm'1to about 100 mS cm'1, such as from about 10 mS cm'1to about 50 mS cm'1, for example from about 25 mS cnr1to about 40 mS cm1. The ion conductivity of the ion-exchange membrane may be measured, for example, by electrochemical impedance spectroscopy in an aqueous electrolyte or deionised water.

[0195] The ion-exchange membranes of the present invention may have an area-specific resistance of from about 0.05 Ohm cm2to about 2.0 Ohm cm2, such as about 0.1 Ohm cm2to about 1 .0 Ohm cm2, such as about 0.3 Ohm cm2to about 0.8 Ohm cm2, for example about 0.5 Ohm cm2to about 0.7 Ohm cm2. The area-specific resistance of the ion-exchange membrane may be measured, for example, by electrochemical impedance spectroscopy in an aqueous electrolyte or deionised water.

[0196] According to a seventh aspect of the present invention, there is provided a battery, comprising an anode and a cathode; wherein the anode and cathode are separated by an ion-exchange membrane according to the fourth or sixth aspect.

[0197] According to an eighth aspect, there is provided a kit of parts for a battery, wherein the kit comprises an anode, a cathode, and an ion-exchange membrane according to the fourth or sixth aspect.

[0198] Features described above in relation to one of the foregoing aspects apply equally, mutatis mutandis, to the other aspects. For example, features described above in relation to the polymer of the first aspect of the invention apply equally to the method of preparing a polymer according to the second aspect, mutatis mutandis.

[0199] According to a ninth aspect, there is provided a polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising wherein R is an aliphatic or aromatic carboxylic acid group; wherein p is from 1 to 100; wherein wherein

[0200] It has been found that, when used in ion-exchange membranes or resins, the polymers disclosed herein show excellent properties in relation to transport of protons and small cations, whilst prohibiting crossover of the large ions and molecules. The ion-exchange membranes claimed herein outperform other membranes (such as Nation™ membranes) in terms of the trade-off between ionic conductivity and selectivity, providing opportunities to improve device performance particularly energy and power density, and device lifetime. It has been found that ion-exchange membranes or resins as disclosed herein may significantly reduce the overall cost of aqueous batteries whilst improving the lifetime and power output.

[0201] Each contorted aromatic moiety may be as defined according to the first aspect; and / or The polymeric backbone may be as defined according to the first aspect;

[0202] R may be as defined according to the first aspect.

[0203] Each side group may be between an adjacent pair of contorted aromatic moieties and collectively these form the backbone, optionally wherein each side group bonds twice to an adjacent contorted aromatic moiety (e.g. which, when taken together with the atoms on the contorted aromatic moiety to which the side group is bonded, forms a ring); or

[0204] The side group may be pendant to the polymeric backbone; and / or Each side group may bond twice to an adjacent contorted aromatic moiety (e.g. which, when taken together with the atoms on the contorted aromatic moiety to which the side group is bonded, forms a ring).

[0205] Suitably, the polymer may be a copolymer of formula: or wherein each of CAi and CA2 are each independently a contorted aromatic moiety (which may be the same or different), or a linear aromatic moiety (which may be the same or different), wherein Sia is said side group, wherein said side group may be bonded by one bond or two bonds; wherein each of Ria, R2a and Rsa are each independently hydrogen or optionally substituted alkyl, haloalkyl, optionally substituted aryl or haloaryl (e.g. optionally wherein the aryl is bicyclic); optionally wherein each Rsa is independently a perfluorinated phenyl or 2,4-di trifluoromethyl phenyl; or wherein Ria is absent, wherein m is from 0 to 1000 (preferably from 100 to 500) and wherein n is from 0 to 1000 (preferably from 100 to 500); wherein at least one of m and n is 1 ; and wherein the sum of m and n is at least 10, optionally at least 200, optionally at least 500, such as at least 800, optionally at least 1000; wherein when said group is connected to the polymeric backbone by two bonds (optionally to form a ring), Ria is absent.

[0206] Suitably, the polymer may be a copolymer of formula: wherein A1 is an aromatic group comprising at least one phenyl group, such as two or three phenyl groups; wherein CA1 is a contorted aromatic moiety; wherein each of Sia and S2a are each independently said side groups (which may be the same or different); wherein said side groups may be bonded by one bond or two bonds; wherein Ria and R2a are each independently absent, hydrogen or optionally substituted alkyl, haloalkyl, optionally substituted aryl or haloaryl (e.g. optionally wherein the aryl is bicyclic); wherein m is from 1 to 1000 (preferably from 100 to 500); wherein n is from 1 to 1000 (preferably from 100 to 500); wherein the sum of m and n is at least 10, optionally at least 200, optionally at least 500, such as at least 800, optionally at least 1000; wherein when said side group bonds twice to an adjacent contorted aromatic moiety (optionally to form a ring), Ria is absent.

[0207] Suitably, each contorted aromatic may comprise a pendant moiety (substituting any available hydrogen), wherein the pendant moiety is:

[0208] (a) fluorinated alkyl, optionally (CF2)3CFs; and / or

[0209] (b) alkoxy, optionally OCH3; and / or

[0210] (c) hydroxyl.

[0211] Ria may be hydrogen or a C1-10 haloalky I group, optionally CF3.

[0212] R2a may be hydrogen or a C1-10 haloalkyl group, optionally CF3.

[0213] Rsa may be optionally substituted C1-10 alkyl, C1-10 haloaryl or optionally substituted C6-20 aryl, e.g. perfluorinated phenyl or 2,4-di trifluoromethyl phenyl.

[0214] Rsa may be selected from optionally substituted:

[0215] Suitably, each contorted aromatic moiety may comprise a ring system with at least two aromatic rings, for example at least three aromatic rings, such as at least four aromatic rings or at least five aromatic rings, optionally wherein the ring system includes one or more heteroatoms.

[0216] For example, the at least two aromatic rings may be phenyl rings, for example at least three phenyl rings, such as at least four phenyl rings or at least five phenyl rings.

[0217] Suitably, each contorted aromatic moiety may comprise about 10 to 100 carbon atoms, optionally about 10 to 75 carbon atoms, optionally about 10 to 50 carbon atoms.

[0218] Suitably, the at least two aromatic rings may be connected by:

[0219] (a) a spiro system;

[0220] (b) a fused ring system;

[0221] (c) a bridged ring system; or

[0222] (d) a single bond and / or double bond. or a combination thereof.

[0223] For example, the at least two aromatic rings may be connected by a spiro system as follows, which may be optionally substituted:

[0224] For example, the at least two aromatic rings may be connected by a fused ring system, wherein the fused ring system comprises one ring fused to said at least two aromatic rings, such as an optionally substituted cyclopentane.

[0225] For example, the at least two aromatic rings may be connected by a bridged ring system, wherein the bridged ring system is carbocyclic, such as one of the following, which may be optionally substituted: or heterocyclic (e.g. heterocyclic equivalents of the aforementioned carbocyclic rings, comprising one or more heteroatoms), optionally comprising one or more nitrogen atoms (e.g. two), such as the following, which may be optionally substituted: optionally wherein the bridged ring system is fused to said at least two aromatic rings.

[0226] Suitably, each contorted aromatic moiety may comprise one of the following, which may be optionally substituted:

[0227] wherein the attachment point may be any suitable substitution of H on the aromatic ring system, and optionally, as shown by the black dots; wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0228] Suitably, each contorted aromatic moiety may comprise one of the following, which may be optionally substituted:

[0229]

[0230] wherein each R29 is independently selected from fc wherein n is from 1 to 20. and wherein the attachment point may be any suitable substitution of hydrogen on the aromatic ring system.

[0231] Suitably, the polymeric backbone may further comprise an aromatic group, optionally wherein the polymeric backbone further comprises one or more of the following: wherein the attachment point may be any suitable substitution of H on the aromatic ring system.

[0232] For example, each contorted aromatic moiety may be optionally substituted: wherein Ri, R2, R3 and R4are each independently selected from hydrogen, C1-10 alkyl, C1-10 alkenyl or Ce-i4aryl, optionally wherein Ri, R2, R3 and R4 are each independently selected from: H, CH3 or tert-butyl; or optionally wherein R1 and R2 and / or Rsand R4 are taken, together with the intervening atoms to which they are attached, to independently form a ring (e.g. a 6 membered ring, optionally aromatic, optionally fused to one or more additional rings which are optionally aromatic), optionally wherein R1and R2and / or R3and R4are taken together with the intervening atoms to which they are attached, to independently form (i.e., to form benzene) and / or wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy

[0233] (preferably OCH3).

[0234] For example, each contorted aromatic moiety may be optionally substituted: wherein R5 and Re are each independently hydrogen or C1-3 alkyl, optionally CH3; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0235] For example, each contorted aromatic moiety may be optionally substituted: wherein R7 and Rs are each independently selected from hydrogen or C1-10 haloalkyl, optionally fluoroalkyl such as (CF2)nCF3 wherein n is from 0 to 9, such as 1 , 3, 5 or 7 or wherein R7 and Rs are taken, together with the intervening atoms to which they are attached, to form a perfluorinated ring, optionally a six membered ring, optionally wherein R7and R8are taken together to form wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3). For example, each contorted aromatic moiety may be optionally substituted: wherein R9, R10, R11 and R12 are each independently selected from hydrogen, fluorine, phenyl, C1-15 alkyl, C1-15 haloalkyl, C1-15 alkenyl or C1-15 haloalkenyl; optionally wherein R9 and R10 are each independently selected from hydrogen or fluorine, or optionally wherein R9 and R10 are taken, together with the intervening atoms to which they are attached, to form optionally substituted with one or more electron withdrawing groups, such as a trihalogenated methyl group, e.g. CF3 groups, and / or such as optionally wherein Rn and R12 are each independently selected from hydrogen, fluorine, phenyl or C1-5 alkyl, such as methyl, ethyl or isopropyl; optionally wherein Rn and R12 are both the same; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0236] For example, each contorted aromatic moiety may be optionally substituted: wherein Rn and R14 are each independently selected from hydrogen, C1-10 alkyl or C1-10 haloalkyl, optionally wherein R13 and R14 are each independently selected from hydrogen or (CH2)n(CH3) wherein n is from 1 to 9, for example 1 , 3, 5 or 7, optionally substituted with one or more fluoro atoms, for example (CF2)nCF3 wherein n is from 1 to 9, for example 1 , 5 or 7; optionally wherein R13 and R14 are the same or wherein R13 and R14 are taken together to form wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0237] For example, each contorted aromatic moiety may be optionally substituted: wherein R15, R16, R17 and Ris are each independently selected from hydrogen or C1-10 alkyl, such as C1- 5 alkyl, for example methyl, ethyl or isopropyl. optionally wherein R15, R16, R17 and Ris are the same; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0238] Suitably, the contorted aromatic moieties may be linked by a linker moiety to form the backbone.

[0239] Suitably, the backbone may be adapted to prevent free rotation of each contorted aromatic moiety relative to said backbone, optionally wherein the linker moiety is adapted to prevent free rotation of each contorted aromatic moiety relative to the said backbone (e.g. wherein the linker moiety bonds to at least two locations on each contorted aromatic moiety).

[0240] Suitably, the or each side group is attached to:

[0241] (a) the or each contorted aromatic moiety; or (b) the linker moiety; or (c) the aromatic group.

[0242] For example, the linker moiety may comprise an optionally substituted phenyl group or heteroaryl group, optionally wherein the linker moiety is optionally substituted: optionally, wherein the linker moiety is wherein each Si is independently said side group, optionally wherein Si is wherein p is from 1 to 100.

[0243] Suitably, the linker moiety may be a single bond or or C1-3 alkyl or C1-3 alkoxy, preferably wherein the linker moiety is a single bond.

[0244] Suitably, the polymeric backbone may comprise a continuous main chain: of carbon atoms, and / or which is substantially ether free, and / or which does not comprise C-O-C moieties.

[0245] Suitably, CA1 and CA2 may be the same; or CA1 and CA2 may be different.

[0246] For example, each contorted aromatic moiety may comprise:

[0247] For example, the contorted aromatic moiety may comprise (e.g. optionally wherein one of CA1 or CA2 comprises):

[0248] Suitably, the polymer may be of formula wherein m is from 1 to 1000 (preferably from 100 to 500); wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500); wherein p is from 1 to 100.

[0249] Suitably, the polymer may be of formula

[0250] wherein n is from 1 to 1000 (preferably from 100 to 500); wherein m is from 1 to 1000 (preferably from 100 to 500); wherein x is from 1 to 1000 (preferably from 100 to 500) and wherein y is from 1 to 1000 (preferably from 100 to 500).

[0251] Suitably, the polymeric backbone may comprise a hydrocarbon core (such as an aromatic hydrocarbon core) with the remainder of the polymeric backbone pendant therefrom, optionally wherein the hydrocarbon core comprises a contorted aromatic moiety and / or wherein the hydrocarbon core comprises one of the following, which may be optionally substituted:

[0252] wherein the remainder of the polymeric backbone is pendant and substitutes any available hydrogen; and optionally, wherein the optional substituents of the hydrocarbon core may comprise one or more contorted aromatic moieties and / or side groups as defined according to the ninth aspect

[0253] Suitably, the polymer may be of formula

[0254] wherein n is from 1 to 1000 (preferably from 100 to 500); wherein m is from 1 to 1000 (preferably from 100 to 500); wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500).

[0255] Suitably, the polymer may be of formula

[0256] wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500).

[0257] According to a tenth aspect, there is provided a polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising wherein the or each side group is attached to the polymeric backbone; and wherein the polymeric backbone further comprises moiety pendant therefrom (optionally wherein said moiety is between adjacent contorted aromatic moieties), where R1-R5 are optionally substituted by hydrogen, fluoride, and CF3.

[0258] Suitably, each contorted aromatic moiety may be as defined according to the first aspect and / or the ninth aspect.

[0259] Suitably, the polymer may be of formula

[0260] wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500).

[0261] According to an eleventh aspect, there is provided an ion-exchange membrane comprising a polymer according to the ninth or tenth aspect.

[0262] According to a twelfth aspect, there is provided use of an ion-exchange membrane according to the eleventh aspect in electrodialysis.

[0263] According to a thirteenth aspect, there is provided use of an ion-exchange membrane according to the eleventh aspect in a redox flow battery.

[0264] According to a fourteenth aspect, there is provided use of an ion-exchange membrane according to the eleventh aspect in ion separation, such as separation of Li+from Mg2+, e.g. in an aqueous solution thereof.

[0265] Suitably, the ion-exchange membrane may be an anion-exchange membrane and wherein said side group comprises

[0266] For example, the anion-exchange membrane may be used in a water electrolyser, a fuel cell, a CO2 electrochemical electrolyser and / or a bipolar membrane.

[0267] Suitably, the ion-exchange membrane may be a zwitterion-exchange membrane comprising the polymer according to the ninth or tenth aspect, wherein said side group comprises

[0268] According to a fifteenth aspect, there is provided, an electrodialysis ion-exchange membrane comprising a polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising C(=NOH)NH2 or COOH.

[0269] Suitably, the ion-exchange membrane may be an electrodialysis ion-exchange membrane, wherein

[0270] (a) each contorted aromatic moiety is as defined according to the first or ninth aspects; and / or (b) the contorted aromatic moieties are linked by a linker moiety to form the backbone; optionally wherein the linker moiety is as defined according to the first aspect.

[0271] Suitably, the polymer in the ion-exchange membrane may be of formula

[0272] (Illa) (Illb) wherein CA is a contorted aromatic moiety;

[0273] Li is a linker moiety; and n is at least 2 (optionally at least 100). optionally, wherein the polymer is of formula

[0274] According to a sixteenth aspect, there is provided use of a polymer of formula as an electrodialysis ion-exchange membrane.

[0275] According to a seventeenth aspect, there is provided a method of preparing a polymer (such as a polymer of intrinsic micro porosity), suitably a polymer according to the ninth or tenth aspect, the method comprising polymerisation of: a monomer A comprising a contorted aromatic moiety CAi; a monomer B comprising a side group Sia or side group precursor SP; to provide an polymer comprising a polymeric backbone comprising contorted aromatic moieties and said at least one side group or side group precursor; optionally wherein the method comprises polymerisation of said monomer B comprising a side group precursor SPand wherein the method further comprises modifying the side group precursor SPof the polymeric backbone to form a side group Sia. For example, each contorted aromatic moiety may be as defined according to the first or ninth aspects, optionally wherein the contorted aromatic moiety is selected from one of the following:

[0276]

[0277] Suitably, monomer B may comprise a side group precursor SPselected from one of the following:

[0278] wherein R1-R5 are each independently selected from hydrogen, fluoride, and CF3; such as

[0279] Suitably, the method may further comprise polymerization of a monomer C comprising an aromatic group A1; optionally wherein A1 is a contorted aromatic moiety as defined in the seventeenth aspect and / or optionally wherein A1 is selected from one of the following:

[0280]

[0281] Suitably, monomer B may comprise a side group Sia selected from one of the following:

[0282] Suitably, polymerization may be performed in the presence of an acid (optionally a sulfonic acid such as trifluoromethanesulfonic acid or methane sulfonic acid; and / or trifluoroacetic acid) and / or an organic solvent such as a chlorinated solvent, optionally wherein wherein polymerization is performed in the presence of:

[0283] (a) trifluoromethanesulfonic acid, trifluoroacetic acid, and dichloromethane; or

[0284] (b) methane sulfonic acid, and dichloromethane.

[0285] Suitably, the side group or side group precursor may comprise the following moiety: and wherein modifying the side group precursor forms a side group selected from:

[0286] Suitably, the method may further comprise a second modification of amidoxime groups with an optionally substituted anhydride to form a side group comprising a carboxylic acid and an oxadiazole moiety, optionally wherein the anhydride is a cyclic anhydride, optionally comprising a ring having at least 5 ring atoms, optionally at least 6 ring atoms, optionally at least 7 ring atoms, optionally wherein the anhydride comprises one or more moieties of formula , which may be optionally substituted in the ring thereof to replace a carbon with one or more heteroatoms, such as oxygen, e.g. optionally wherein the anhydride is

[0287] For example, the anhydride may comprise at least one phenyl group, such as two phenyl groups or three phenyl groups, for example four phenyl groups or five phenyl groups (e.g. pendant or fused to the remainder of the anhydride).

[0288] Suitably, the anhydride may be optionally substituted with one or more halogens, for example fluorine.

[0289] For example, the anhydride may be selected from any one of the following:

[0290]

[0291] Suitably, the side group precursor may comprise the following moiety: and wherein modifying the side group precursor forms a side group selected from:

[0292] Examples

[0293] Experimental methods

[0294] Membrane fabrication

[0295] Polymers were dissolved in DMSO or NMP to afford a homogeneous solution with polymer concentration in the range of 1~20 wt.% (preferably 2-8 wt.%). The solutions were centrifuged at 12,000 rpm for 10 min or filtered through a pad of glass wool to remove impurities. The solutions were then poured into glass Petri dishes or blade-casted on a glass plate. After the formation of uniform liquid films on glass plates or Petri dishes, they were kept in an oven at elevated temperatures (60-120 °C) to allow solvent evaporation for 24 h. Afterwards, polymer films were peeled off upon immersion in water and stored in deionised water.

[0296] Nuclear magnetic resonance (NMR)

[0297] 1H and13C NMR spectra were collected at 60 °C using Jeol 400 MHz and Bruker Avance III HD 600 MHz spectrometers, respectively. 3-6 vol.% TFA was used in1H NMR measurements to shift water peak.

[0298] Fourier-transform infrared (FT-IR) spectroscopy

[0299] FT-IR spectroscopy was performed on a Perkin-Elmer Spectrum 100 FTIR spectrometer with polymer membrane samples mounted on a zinc-selenium / diamond plate.

[0300] N2 / CO2 physisorption

[0301] Low-pressure gas physisorption was performed using a Micromeritics 3Flex surface characterization analyser. Each sample was degassed at 110 °C under vacuum for 12 h, and then loaded into the apparatus and in situ degassed at 110 °C for another 12 h. Nitrogen adsorption isotherms were measured at 77 K, and CO2 adsorption isotherms were measured at 273 K. Electrochemical Impedance Spectroscopy (EIS) Membrane samples were treated in 1M aqueous KOH overnight to deprotonate carboxylic acid groups; membranes were then soaked in 1M aqueous KCl with multiple change of solutions before measurements. The membranes were sandwiched between two stainless steel electrodes and sealed with coin cells (Type 2032) for measurement at elevated temperatures. The ionic conductivity was calculated according to the following equation: σ = L / (Rm× A) where Rm is the ionic resistance, L is membrane thickness and A is the active membrane area (2.00 cm2). Crossover measurement Redox molecule crossover tests were performed using stirred H-shaped cells. Membranes were sandwiched between two crosslinked polydimethylsiloxane O-rings and placed in the middle 2 of H- shaped cells. The effective area of the membrane samples in the H-shaped cell was 1.54 cm. Feed and permeate solutions were stirred to alleviate concentration polarization near membrane surfaces. Aliquots were taken from the permeate solution, diluted with 2 wt.% aqueous HNO3, and subjected to ICP-MS measurements to quantify iron concentration. Permeation rate (flux) of ions and redox molecules across the membrane follows Fick’s first law: J=V / A(∂C / ∂t) where J is the permeation rate (mol cm-2s-1), V is the solution volume (mL), A is the effective membrane area (1.54 cm2), C is the concentration of the permeate solution (mol cm-3) and t is diffusion time (s). As C2 << C1 and C1 – C2 ≈ C1, under the assumption that boundary resistances next to the membrane are negligible, Fick’s first law can be simplified as: J=D(C1-C2) / l=DC1 / l where D is the permeability (cm2s-1), C1is the concentration of the feed solution (mol cm-3) and l is membrane thickness (cm). It should be noted that permeability used throughout the thesis corresponds to the diffusion coefficient of a solute in the membrane phase. Redox flow battery full-cell tests Cell hardware was assembled into a zero-gap flow cell configuration using cell hardware (Scribner Associates). Electrodes employed a stack of three or four sheets of graphite papers (Sigra 2cet 39AA, Fuel Cell Store) with a nominal thickness of 0.28 o mm and an effective geometric area of 7 cm. Graphite papers were thermally treated in the air at 400 C for 24 h before use. Hydroxide and carboxyl groups can be introduced through the thermal treatment and facilitate the on-surface redox reaction of redox −1- active species in aqueous solutions. Electrolytes were fed into the cell at a flow rate of 60 ml min controlled by a peristaltic pump (Cole-Parmer). Galvanostatic cycling tests were performed using an electrochemical station (Biologic SP-150 potentiostat) at constant current density / room temperature. Nafion membranes were heated to 80 °C in deionized water for 20 min and then soaked in 6% hydrogen peroxide solution for 35 min. After pretreatment, Nafion 212 membranes were stored in 0.1 M KOH aqueous solution. Example 1: Precursor Compound DABD-SA DMSO (20 mL) was added to DABD (0.30 g, 0.74 mmol) and succinic anhydride (0.32 g, 3.2 mmol). The mixture was stirred at room temperature for 3 h and potassium ethoxide (0.53g, 6.3 mmol) added to the solution. The mixture was vigorously stirred for 1.5 h and then poured into 400 mL water. Hydrochloric acid was added dropwise to adjust the pH to 1-2. The precipitate was filtered, washed with water and dried at 110°C under vacuum to afford a cream-colour powder (0.32g, 76%). The structural characterisation is shown in Figure 1, as follows:1H NMR (500 MHz, (CD3 2.89 (s, 4H).1)2SO): δ (ppm) 12.48 (br s, 2H), 6.99 (s, 4H), 6.86 (s, 4H), 3.29 (s, 4H) and3C NMR (125 MHz, (CD3)2SO): δ (ppm) 179.9, 172.7, 160.0, 140.1, 136.1, 125.1, 116.5, 106.6, 30.0 and 21.7.

[0302] AO-PIM-1 solution (2.01 g, 3.8 mmol repeating units, 2 wt.% in DMSO) was added to succinic anhydride in one portion (1 .53 g, 15.3 mmol). The mixture was stirred at 30 °C for 4 h and then potassium ethoxide was added (5.12g, 60.8 mmol). The mixture was vigorously stirred at room temperature for 1 h and then poured into 400 mL water. Hydrochloric acid was added dropwise to the solution until pH was adjusted to 1-2. The precipitate was filtered, suspended in 0.5M aqueous H2SO4 and heated to reflux for 4 h. The powder was collected by filtration, washed with deionised water until the pH of the washing solution became neutral and dried in air at 1 10°C to yield cPIM-SA (2.35 g, 85%) as a yellow powder.

[0303] Example 3: cPIM

[0304] AO-PIM-1 solution (1 .01 g, 1 .9 mmol repeating units, 2 wt.% in DMSO) was added to phthalic anhydride in one portion (1 .22 g, 8.2 mmol). The mixture was stirred at 30 °C for 4 h and then potassium ethoxide was added (2.56 g, 30.4 mmol). The mixture was vigorously stirred at room temperature for 1 h and then poured into 200 mL water. Hydrochloric acid was added dropwise to the solution until pH was adjusted to 1-2. The precipitate was filtered, suspended in 0.5M aqueous H2SO4 and heated to reflux for 4 h. The powder was collected by filtration, washed with deionised water until the pH of the washing solution became neutral and dried in air at 110°C to yield cPIM-SA (1 .37 g, 88%) as a yellow powder.

[0305] Example 4: cPI

[0306] AO-PIM-1 solution (0.50 g, 0.95 mmol repeating units, 2 wt.% in DMSO) was added to diphenic anhydride in one portion (0.85 g, 3.8 mmol). The mixture was stirred at 30 °C for 4 h and then potassium ethoxide was added (1 .28 g, 15.2 mmol). The mixture was vigorously stirred at room temperature for 1 h and then poured into 100 mL water. Hydrochloric acid was added dropwise to the solution until pH was adjusted to 1-2. The precipitate was filtered, suspended in 0.5M aqueous H2SO4 and heated to reflux for 4 h. The powder was collected by filtration, washed with deionised water until the pH of the washing solution became neutral and dried in air at 110 °C to yield cPIM-SA (0.67 g, 75%) as a yellow powder.

[0307] The structural characterisation for each of Examples 2-4 is shown in Figure 2. The chemical structures of Examples 2-4 and their nanoscale porosities are characterized in Figure 3.

[0308] Example 5 pPIM-SBI-PFB

[0309] A solution of PIM-SBI-PFB (1 .6 g, 3.11 mmol) in DMAc (20 mL) was added to tris(trimethy lsilyl)phosphite (6.251 g, 21 mmol) dropwise. The reaction solution was then heated to 180°C for 12h. The reaction solution was cooled down to room temperature and precipitated in water and collected in filtration. The resulting white fibrous product was suspended in 2 wt% phosphoric acid solution and heated to reflux, followed by washing with abundant water. The polymer was then collected by filtration, dried at 120°C to yield pPIM-SBI-PFB (1 .33 g, 72%). The porosity and proton conductivity of pPIM-SBI-PFB are shown in Figure 7.

[0310] Example 6: Property Studies

[0311] The ion transport functions for each of Examples 2-4 are shown in Figure 4, and the performance of Examples 2-4 in aqueous organic redox flow batteries are shown in Figures 5 and 6. The resulting ion conductive membranes exhibited high ionic conductivity and ultrahigh selectivity towards redox-active species. The ion transport performance of these membranes appeared far above the upper bound limits for both commercial ion exchange membranes and conventional PIM membranes reported in the literature,1resulting in the energy efficiency and cycling stability of electrochemical devices being significantly improved.

[0312] For example, cPIM-PA (Example 3) gave an ionic conductivity of 13.8 mS cm-1and a ferrocyanide permeability of 4 x 10-14cm2s-1, several orders of magnitude lower than the value for Nation™ membranes (10-9cm2s-1). The cPIM-PA membrane also delivered a low high-frequency area-specific cell resistance of 1.2 Ohm cm2and a high peak power density of 192 mW cm-2in an anthraquinone|ferrocyanide RFB, superior to an otherwise-identical RFB based on Nation™ 212 membrane (1.5 Ohm cm2, 159 mW cm-2) and sulfonated poly(ether ether ketone) membrane (sPEEK, 2.2 Ohm cm2, 116 mW cm2). The high selectivity of cPIM-PA (example 3) enabled ultrahigh cycling stability of the RFB using nearly capacity-balanced anolyte and catholyte, showing a decay rate as low as 0.014%. The decay rate is 10-100 times lower than that of otherwise-identical RFBs based on the benchmark Nation™ 212 membrane and the sPEEK membrane. Postmortem analysis of the electrolytes confirmed membrane crossover as the major decay mechanism. Such a combination of high cycling stability and high energy density demonstrated here exceeds all previously reported RFB systems. In addition, high energy efficiency was demonstrated and appeared superior to previously reported energy- dense RFBs based on conventional membranes owing to the low ionic resistance of the cPIM-APA membrane.

[0313] Example 7: Synthesis of PIM-1

[0314] PIM-1 : 5,5',6,6'-Tetrahyroxy-3,3,3,‘3'-tetramethyl-1 ,1 '-spirobisindane (TTSBI) (3.40 g, 10.0 mmol) and

[0315] 2, 3, 5, 6- tetrafluoroterephthalonitrile (TFTPN) (2.00 g, 10.0 mmol) were added to a 250 mL three-neck- round-bottomed flask and pre-flashed with nitrogen, before being dissolved in anhydrous DMAc (18.0 mL). Once a clear solution formed, the flask was placed under reflux at 150°C, followed by the addition of K2CO3 fine powder (3 x 1.17 g, 25.4 mmol) over 5 minutes, where the resulting solution increases significantly in viscosity 0.5 h. Subsequently, three portions of toluene (3 x 2 mL) are added over 10 mins, and the solution is left to stir for 1 h. The polymer solution is poured into methanol (200 mL) and left to stir. After filtering and drying overnight, the solid is dissolved in chloroform and re precipitated in methanol. Finally, the polymer is refluxed in water overnight to remove any residual salts and dried in a vacuum oven at 110°C for 12h to give PIM-1 as a yellow powder at 94% yield.

[0316] Example 8: Synthesis of AO-PIM-1

[0317] To a 1 L reactor flask was added 20 g of PIM-1 dissolved in 800 mL of THF. Once dissolved, the solution was set to reflux at 69 °C under argon using a waterless condenser. Hydroxylamine (200 mL) was added dropwise using a dropping funnel to allow the precipitate to redissolve. Stirring was maintained for a further 20 h, and the solution was precipitated in ethanol (3 L). The AO-PIM-1 polymer was filtered under vacuum and washed thoroughly with DI water and ethanol, followed by drying overnight to give AO- PIM-1 at 93% yield.

[0318] Example 9: Synthesis of SBI-OH

[0319] In a 500 ml round bottom flask under nitrogen flow, 200 g (870 mmol) of bisphenol A (BPA) was added and the flask heated to 135 °C to melt the solid. Then, 10 ml of methanesulfonic acid (MSA) was added and the solution stirred for 6h. The mixture was cooled to room temperature and then poured into vigorously stirred water for 2 h. The yellow precipitate was collected by filtration and dried overnight under vacuum. The yellow solid was recrystallized from a 1 :1 water / ethanol mixture to yield 3, 3,3', 3'- Tetramethyl-1 ,1 '-spirobisindane-6,6'-diol (SBI-OH) as white crystals which were dried overnight under vacuum at 100 °C.

[0320] In a 200 ml round bottom flask submerged in an ice bath, 20 g (65 mmol) of SBI-OH was dissolved in acetone under mechanical stirring. 45 g of potassium carbonate was added, and the mixture stirred for 30 min. Then 41 g (325 mmol) of dimethyl sulfate was added dropwise and the reaction was stirred for 12 h. The mixture was poured onto ice under stirring and the white precipitate collected by filtration. The white solids were washed repeatedly with water. The product was purified by recrystallisation from petroleum ether to obtain SBI-OMe as white crystals.

[0321] Example 11 : Synthesis of PIM-SBI-OMe-CN

[0322] In a 100 ml round bottom flask with a magnetic stirrer, 1.70 g (13 mmol) of 4-formylbenzonitrile was dissolved in 20ml dichloromethane (DCM). 3.06 g (10mmol) of SBI-OMe was added to form a clear dark brown solution. Then 5 ml of methanesulfonic acid (MSA) was added dropwise. The reaction was left to stir for 30 minutes when a viscous solution was formed. The solution was poured into stirred methanol to precipitate a fibrous white polymer (PIM-SBI-OMe-CN). The polymer was washed repeatedly with water to remove residual acid and finally washed with methanol before drying overnight in air at 100 °C. The dried polymer was dissolved in THF and precipitated in methanol to obtain the purified polymer as a white powder.

[0323] Example 12: Synthesis of PIM-SBI-OH-CN

[0324] In a 100 ml round bottom flask with a magnetic stirrer, 1.70 g (13 mmol) of 4-formylbenzonitrile was dissolved in 20ml dichloromethane (DCM). 3.06 g (10mmol) of SBI-OH was added. Then 3 ml of methanesulfonic acid (MSA) was added dropwise. The reaction was left to stir for 5 minutes when a viscous solution was formed. The solution was poured into stirred water to precipitate a fibrous white polymer (PIM-SBI-OH-CN). The polymer was washed repeatedly with water to remove residual acid and finally washed with a 1 :1 water / methanol solution before drying overnight in air at 100 °C. The dried polymer was dissolved in THF and precipitated in methanol to obtain the purified polymer as a white powder.

[0325] Example 13: Synthesis of PIM-SBI-OMe-5F-CN

[0326] In a 100 ml round bottom flask with a magnetic stirrer, 1.45 g (11.05 mmol) of 4-formylbenzonitrile and 0.38 g of 2,3,4,5,6-pentafluorobenzaldehdye (1.95 mmol) were dissolved in 20ml dichloromethane (DCM). 3.36 g (10mmol) of SBI-OMe was added to form a clear brown solution. Then 5 ml of methanesulfonic acid (MSA) was added dropwise. The reaction was left to stir for 30 minutes when a viscous solution was formed. The solution was poured into stirred methanol to precipitate a fibrous white polymer (PIM-SBI-OMe-5F-CN). The polymer was washed repeatedly with water to remove residual acid and finally washed with methanol before drying overnight in air at 100 °C. The dried polymer was dissolved in THF and precipitated in methanol to obtain the purified polymer as a white powder.

[0327] Example 14: Synthesis of PIM-SBI-OH-5F-CN

[0328]

[0329] In a 100 ml round bottom flask with a magnetic stirrer, 1.45 g (11.05 mmol) of 4-formylbenzonitrile and 0.38 g of 2,3,4,5,6-pentafluorobenzaldehdye (1.95 mmol) were dissolved in 20ml dichloromethane (DCM). 3.06 g (10mmol) of SBI-OH was added to form a clear brown solution. Then 3 ml of methanesulfonic acid (MSA) was added dropwise. The reaction was left to stir for 5 minutes when a viscous solution was formed. The solution was poured into stirred methanol to precipitate a fibrous white polymer (PIM-SBI-OH-5F-CN). The polymer was washed repeatedly with water to remove residual acid and finally washed with a 1 :1 water / methanol solution before drying overnight in air at 100 °C. The dried polymer was dissolved in THF and precipitated in methanol to obtain the purified polymer as a white powder.

[0330] Example 15: Synthesis of PIM-SBI-OMe-2CF3-CN

[0331] In a 100 ml round bottom flask with a magnetic stirrer, 1.45 g (11.05 mmol) of 4-formylbenzonitrile and 0.45 g of 3,5-Bis(trifluoromethyl)benzaldehyde (1.95 mmol) were dissolved in 20ml dichloromethane (DCM). 3.36 g (10mmol) of SBI-OMe was added to form a clear brown solution. Then 5 ml of methanesulfonic acid (MSA) was added dropwise. The reaction was left to stir for 30 minutes when a viscous solution was formed. The solution was poured into stirred methanol to precipitate a fibrous white polymer (PIM-SBI-OMe-2CF3-CN). The polymer was washed repeatedly with water to remove residual acid and finally washed with a 1 :1 water / methanol solution before drying overnight in air at 100 °C. The dried polymer was dissolved in THF and precipitated in methanol to obtain the purified polymer as a white powder.

[0332] Example 16: Synthesis of AO-PIM polymers

[0333] I dropping funnel, 2 g of PIM polymer was dissolved in 80 ml of DMSO. The polymer solution was heated to 100 °C under stirring. Then, 30 ml of hydroxylamine (NH2OH) was added dropwise via the dropping funnel. On complete addition, the reaction mixture was left to stir overnight at 100 °C before allowing to cool to room temperature. Once cooled, the precipitated polymer was obtained by filtration and washed repeatedly with water before drying overnight in an oven.

[0334] Example 17: Synthesis of carboxylate PIM polymers cPIM-1 : To a 1 L round-bottomed flask containing PIM-1 (10 g) as a fine powder, DI water (250 mL), glacial acetic acid (83 mL) and concentrated sulfuric acid (250 mL) were added in sequence. The reaction flask was refluxed at 150°C for 48 h. The solution was then cooled, and vacuum filtered directly. The powder was washed abundantly with DI water, with the pH being checked throughout. The powder was then transferred to a 1 L round-bottomed flask containing 0.1 M aqueous sulfuric acid (500 mL) and heated to reflux overnight. The powder was then filtered, washed abundantly with DI water, and dried overnight to give cPIM-1 as a dark orange powder at 95% yield. cPIM-1 -OMe: To a two-neck round bottomed flask containing cPIM-1 (0.5 g, 1 .00 mmol), K2CO3 (1.11 g, 8.02 mmol) and anhydrous DMF (12.5 mL) were mixed and stirred at room temperature under argon atmosphere. An excess of Me-I (1 .42 g, 10.03 mmol) was added in the dark under vigorous stirring. The solution was left to stir overnight and was precipitated in DI water. The polymer was washed abundantly in DI water at least twice, filtered under vacuum and dried overnight to give cPIM-1-OMe as a yellow powder at 90 % yield.

[0335] Example 19: Synthesis of 5

[0336] The combined solutions of sodium hydroxide (6.42 g, 0.161 mol) in water (10 mL) and methoxypolyethylene glycol (mPEG) (44.1 g, 0.126 mol) in THF (10 mL) were added in sequence to a 250 ml round bottomed flask cooled in an ice bath and stirred for 30 mins. The solution of TsCI (25.54 g, 0. 134 mol) in THF (30 mL) was added dropwise over 15 mins. After, the reaction mixture was allowed to warm to room temperature and stirring was maintained for a further 15h. Aqueous sulfuric acid (6M, 50 mL) was added to the reaction mixture which was then extracted with DCM (2 x 50 mL). The organic layers were combined, washed with water (3 x 50 mL) and dried over anhydrous Na2SO4 followed by gravity filtration. The filtrate was concentrated under vacuum to give 5 (41 .52 g, 0.08 mol, 66.7 %) as a light-yellow oil.

[0337] Example 20: Synthesis of 6

[0338] Nal (8.79 g, 58.6 mmol) was added in the dark, with vigorous stirring, to 5 (10.51 g, 13.6 mmol) dissolved in anhydrous acetone (50 mL), and the resulting yellow mixture was stirred for 24 h under reflux at about 60°C. A yellow solid eventually settled down in the reaction flask. After evaporating acetone using a rotary evaporator, DCM (60 mL) and DI water (40 mL) were added to the solid left behind in the flask. The mixture was stirred for 30 min at RT. The organic and aqueous phases were separated, and the organic phase was extracted with 5% aqueous Na2S20s solution (3 x 50 mL). The organic phase was further washed with saturated NaHCOs solution (3 x 50 mL) and with DI water (3 x 50 mL) and dried over sodium sulphate. The sodium sulphate was removed by gravity filtration and DCM was evaporated under vacuum. The product was further dried in a vacuum oven at 50 °C to obtain 8.95 g of a yellow oil of ether-containing monomer (6), used in the next reaction without further purification.

[0339] Example 21 : Synthesis of oliqoether-functionalized PIM polymers

[0340] PIM-EO: cPIM-1 (0.50 g, 1 .00 mmol) was added to a 100 mL two-neck round-bottomed flask pre-flashed with argon and dissolved using anhydrous DMF (12.5 mL) at room temperature. Once dissolved, fine K2CO3 (1.1 1 g, 8.02 mmol) was added in one portion, followed by the addition of ether-containing monomer (1 .35 g, 3.01 mmol). The solution was gradually heated from 40°C, increasing by 20°C every 0.5 h until it reached 100°C, and was left to stir overnight. The solution is then cooled to room temperature and precipitated in DI water and washed at least twice with excess DI water. The polymer was filtered under vacuum and dried at 100°C overnight to give PIM-EO as a brown powder at 80% yield.

[0341] Example 22: Synthesis of oliqoether-functionalized PIM polymers

[0342] PIM-OMeo.67-EOo.33: c-PIM-1 (0.50 g, 1.00 mmol) was added to a 100 mL two-neck round-bottomed flask pre-flashed with argon and dissolved using anhydrous DMF (12.5 mL) at room temperature. Once dissolved, fine K2CO3 (1 .1 1 g, 8.02 mmol) was added in one portion, followed by the addition of ether- containing monomer (0.45 g, 1.00 mmol). The solution was gradually heated from 40°C, increasing by 20°C every 0.5 h until it reached 100°C, and was left to stir overnight. The solution is then cooled to room temperature and an excess of Me-I (1.42 g, 10.03 mmol) was added in the dark. Stirring was continued for an additional 12 hours, after which the solution was precipitated in DI water and washed at least twice with excess DI water. The polymer was filtered under vacuum and dried at 100°C overnight to give PIM-OMeo.67-EOo.33 (90% yield) as a dark yellow powder.

[0343] Example 23: Synthesis of oligoether-functionalized PIM polymers

[0344] PIM-OMeo.83-EOo.17: cPIM-1 (0.50 g, 1 .00 mmol) was added to a 100 mL two-neck round-bottomed flask pre-flashed with argon and dissolved using anhydrous DMF (12.5 mL) at room temperature. Once dissolved, fine K2CO3 (1 .1 1 g, 8.02 mmol) was added in one portion, followed by the addition of ether- containing monomer (0.23 g, 0.50 mmol). The solution was gradually heated from 40°C, increasing by 20°C every 0.5 h until it reached 100°C, and was left to stir overnight. The solution is then cooled to room temperature and an excess of Me-I (1.42 g, 10.03 mmol) was added in the dark. Stirring was continued for an additional 12 hours, after which the solution was precipitated in DI water and washed at least twice with excess DI water. The polymer was filtered under vacuum and dried at 100°C overnight to give PIM-OMeo.83-EOo.17 as a yellow powder (83 % yield).

[0345] Example 24: Synthesis of oligoether-functionalized PIM polymers

[0346] PIM-OMe0.90-EO0.10: cPIM-1 (0.50 g, 1 .00 mmol) was added to a 100 mL two-neck round-bottomed flask pre-flashed with argon and dissolved using anhydrous DMF (12.5 mL) at room temperature. Once dissolved, fine K2CO3 (1 .1 1 g, 8.02 mmol) was added in one portion, followed by the addition of ether- containing monomer (0.1 1 g, 0.25 mmol). The solution was gradually heated from 40°C, increasing by 20°C every 0.5 h until it reached 100°C, and was left to stir overnight. The solution is then cooled to room temperature and an excess of Me-I (1.42 g, 10.03 mmol) was added in the dark. Stirring was continued for an additional 12 hours, after which the solution was precipitated in DI water and washed at least twice with excess DI water. The polymer was filtered under vacuum and dried at 100°C overnight to give PIM-OMe0.90-EO0.10 (89% yield) as a yellow powder.

[0347] Example 25: Synthesis of oligoether-functionalized PIM polymers PIM-COOHo ,67“EOO,33- CPIM-1 (0.50 g, 1.00 mmol) was added to a 100 mL two neck round bottomed flask pre-flashed with argon and dissolved using anhydrous DMF (12.5 mL) at room temperature. Once dissolved, fine K2CO3 (1 .1 1 g, 8.02 mmol) was added in one portion, followed by the addition of ether- containing monomer (0.45 g, 1.00 mmol). The solution was gradually heated from 40°C, increasing by 20°C every 0.5 h until it reached 100°C, and was left to stir overnight. The solution was precipitated in DI water and washed at least twice with excess DI water. The polymer was filtered under vacuum and dried at 100°C overnight to give PIM-COOH0.67-EO0.33 (89% yield) as a yellow powder.

[0348] Example 26: Synthesis of oligoether-functionalized PIM polymers

[0349] PIM-COOH0.83-EO0.17: cPIM-1 (0.50 g, 1.00 mmol) was added to a 100 mL two-neck round-bottomed flask pre-flashed with argon and dissolved using anhydrous DMF (12.5 mL) at room temperature. Once dissolved, fine K2CO3 (1 .1 1 g, 8.02 mmol) was added in one portion, followed by the addition of ether- containing monomer (0.23 g, 0.50 mmol). The solution was gradually heated from 40°C, increasing by 20°C every 0.5 h until it reached 100°C, and was left to stir overnight. The solution is then cooled to room temperature and an excess of Me-I (1.42 g, 10.03 mmol) was added in the dark. Stirring was continued for an additional 12 hours, after which the solution was precipitated in DI water and washed at least twice with excess DI water. The polymer was filtered under vacuum and dried at 100°C overnight to give PIM-COOH0.83-EO0.17 (89% yield) as a yellow powder.

[0350] Example 27: Synthesis of oligoether-functionalized PIM polymers

[0351] PIM-COOHo .90-EO0.10: cPIM-1 (0.50 g, 1.00 mmol) was added to a 100 mL two-neck round-bottomed flask pre-flashed with argon and dissolved using anhydrous DMF (12.5 mL) at room temperature. Once dissolved, fine K2CO3 (1 .1 1 g, 8.02 mmol) was added in one portion, followed by the addition of ether- containing monomer (0.1 1 g, 0.25 mmol). The solution was gradually heated from 40°C, increasing by 20°C every 0.5 h until it reached 100°C, and was left to stir overnight. The solution is then cooled to room temperature and an excess of Me-I (1.42 g, 10.03 mmol) was added in the dark. Stirring was continued for an additional 12 hours, after which the solution was precipitated in DI water and washed at least twice with excess DI water. The polymer was filtered under vacuum and dried at 100°C overnight to give PIM-COOH0.90-EO0.10 (89% yield) as a yellow powder.

[0352] Example 28: Electrodialysis experiments

[0353] This study uses two kinds of lab-scale ED stack equipped with polymers of intrinsic microporosity (PIMs) and anion-exchange membranes placed in parallel (Fig. 8). For small electrodialysis stack, the effective area of each membrane is 2 cm2. In the stack, 1 cm-thick channels separate two neighbouring membranes. For large electrodialysis stack with effective membrane area of 189 cm2, 1 mm-thick channels separate two neighbouring membranes. The ED stack was operated in a galvanostatic mode controlled by a direct current supply. The voltage was recorded every 20 mins for small-scale ED stack and every 1 hour for large-scale ED stack.

[0354] In the electrodialysis experiments, the mixed ion (K+, Na+, Li+, and Mg2+) solution and DI water were pumped into dilute and concentrate chambers separately, with a volumetric flow rate of 40 mL / min. The Na2SO4 was pumped into electrode chamber, with volumetric flow rate of 80 mL / min. The electrodialysis experiments were performed in a batch mode in which the effluent streams were circulated back to the respective tanks. For small electrodialysis stack with effective area of each membrane 2 cm2, the experiment normally took 2 hours in total. For small electrodialysis stack with effective membrane area of 2 cm2, the experiment normally took 2 hours in total with current density 1 or 1.5 or 2 or 2.5 or 3 mA / cm2. While for large electrodialysis stack with effective membrane area of 189 cm2, the experiment normally took 8 hours in total with current density 2 mA / cm2. Samples were collected every 20 mins for small electrodialysis stack and every 1 hour for large electrodialysis stack to measure the concentration of each cation by using Inductively coupled plasma mass spectrometry (ICP-MS).

[0355] Calculation

[0356] The permeation rate is defined as the mole of a specific ion i extracted per membrane area per time. The permeation rate of i, Pi t(mol m-2h-1) from time 0 to time t can be calculated using the following equation:

[0357] Where Ci trefers to the concentration of i ion in time t in the concentration chamber (mol / L), Vc tand Vco referto the volume of the concentrate chamber (L) at time t and 0, and A is the area of the membrane (m2).

[0358] The selectivity of membranes to other cations M+(K+, Na+, Li+) over Mg2+into concentrate chambers is defined as the ratio of the ion fluxes normalized by their initial concentrations, at time t: rM M9

[0359] Where PM tand PMg,tarethe permeation rate o and Mg2+at time t (mol m -2h’1), CMand CMgare the feed concentrations of M+(K+, in the dilute chamber (mol / L).

[0360] Example 29: Electrodialysis separation performance of AO-PIM-1 membrane

[0361] The electrodialysis performance of PIM membranes was evaluated in laboratory scale electrodialysis cells with an effective area of 2 cm2. The current density was varied in the range of 1-3 mA cm-2. Binary salt mixtures were prepared and evaluated, including KCI / MgCL, NaCI / MgCh, and LiCI / MgCh. The concentrations of ions were quantified by ICP-MS. Firstly, AO-PIM-1 membrane was tested for Li / Mg, K / Mg, and Na / Mg binary ion separation under different current densities (1 , 1 .5, 2, 2.5, 3 mA cm-2). As shown in Fig. 9a, AO-PIM-1 could achieve optimal performance and high ion selectivity under 2 mA cm-2. Under high current densities (3 mA cm2), only Li+but also Mg2+exhibited higher permeation rate through membrane, resulting in lower selectivity (only around 50). We also evaluated the separation performance of AO-PIM-1 for binary K / Mg and Na / Mg mixtures under different current densities. Under higher current density, the permeation rate of K+was higher (1 .02 mol nr2h-1), with an impressively high K / Mg selectivity of 1500 at current density 2 mA / cm2(Fig. 9b). AO-PIM membrane also gave high Na+permeation rate 0.4 mol nr2h1and Na / Mg selectivity up to 300 under current density 2 mA / cm2(Fig. 9c). These results demonstrate that pristine AO-PIM-1 could have effective separation for monovalent ions and divalent ions.

[0362] Pristine AO-PIM membranes show a size-exclusion phenomenon (Fig. 9d), with fast diffusion of smaller monovalent alkali metal cations (K+, Na+, Li+) with permeation rates of 0.2-1 .0 mol m-2h-1while rejecting larger divalent cations (Mg2+) with slower permeation rates around 10-2mol m-2h-1. Based on the permeations rates, we derived the selectivity of monovalent ions over Mg2+(Fig. 9e). AO-PIM-1 membrane showed excellent monovalent / divalent ion selectivity, with K7Mg2+selectivity at 1500, Na+ / Mg2+selectivity at 300, and Li+ / Mg2+selectivity about 230. The difference in selectivity can be attributed to the size-sieving of salt ions through the subnanometer channels in PIM polymer membranes.

[0363] The selective ion separation performance was further confirmed using a salt mixture of KCI / NaCI / LiCI / MgCh (Fig. 9f). The monovalent / divalent ion selectivity is relatively lower than that of binary mixtures, due to the competitive ion transport between small cations through the channels. K+ions showed the highest permeation rate (0.46 mol nr2h1) with high K / Mg selectivity of 420. Na+had slightly lower permeation rate (0.36 mol nr2tr1) with Na / Mg selectivity of 330. As K+and Na+ions showed competitive transport with Li+, the permeation rate of Li+was 0.13 mol nr2h-1and Li / Mg selectivity of 120. The performance of AO-PIM-1 in binary mixtures with varied Mg2+ / Li+mass ratios (10, 20, 40, 60, and 80) were also investigated. Selective separation of Li+and Mg2+were achieved under all mass ratios of Li+to Mg2+, and when the mass ratio of Mg / Li was 20, the Li / Mg selectivity was the highest (around 240). The AO-PIM-1 membrane also maintained reasonably high selectivity (>100) with the electrolyte concentration increased from 0.05M to 1 M. Example 30: Electrodialysis separation performance of AO-PIM-1 membrane in stack

[0364] To demonstrate the upscaling potential of and recyclability of PIM membranes for lithium extraction, a large sheet of AO-PIM-1 membrane was prepared and paired with two pieces of AEM membranes for the electrodialysis tests (Fig. 10a). These membranes were assembled into one lab-scale electrodialysis stack with an effective area of 189 cm2(Fig. 10b and 10c). The performance of AO-PIM-1 membrane was evaluated with KCI / NaCI / LiCI / MgCh mixed solution with initial concentration of 0.1 M for each ion. After testing for 10 hours, K+concentration increased to over 0.3 mol L-1. The final concentrations of Na+and Li+were about half of the K+, and Li+was slightly lower than that of Na+. Mg2+ions showed negligible change with time compared to K+, Na+, and Li+(Fig. 10d). Fig. 10e shows the permeation rate and selectivity of AO-PIM-1 for ion separation using the large-area stack. The results in the stack still demonstrated preferential transport of K+, Na+and Li+with high selectivity towards Mg2+. The Li / Mg selectivity was still as high as 100, the resulting permeate salt mixtures contain KCI, NaCI, and LiCI. The final product solution was evaporated to enhance Li+concentration to over 3 mol L1. Lithium can be precipitated easily using Na2CO3, resulting in the production of high purity battery-grade U2CO3 with purity up to 99.6 wt% based on ICP measurement. The X-ray diffraction pattern of precipitated U2CO3 product is shown in Fig. 10f. These results confirmed that AO-PIM-1 has the potential to be scaled up with great promise for electrodialysis.

[0365] Table 1 : Nominal Ionic Composition of Hypersaline Brine from Salt-Lake Reservoirs (diluted 2 times) and product solution after one stage electrodialysis process.

[0366] Further experiments were conducted to test the performance of AO-PIM-1 membranes with salt mixtures with similar compositions to hypersaline brine extracted from salt-lake reservoirs (Fig. 10g, Table 1). The volume of feed simulated salt-lake brine solution to the dilute chamber was 1 L while the volume of feed solution (DI water) to the concentrate chamber was 200 mL. After 8 hours of continuous testing, Na+concentration could reach around 0.7 mol / L with K+concentration increased up to 0.075 mol / L. The concentration of Li+could be enriched to 1.17 g / L (0.17 mol / L) and Mg2+was 2.65 g / L (0.11 mol / L). Li+transport was relatively slow due to the low initial concentration and competition transport, yet the Li / Mg selectivity is still as high as 30 despite the initial high Mg2+ / Li+mass ratio (~65) (Fig. 10h). The overall monovalent / divalent ion selectivity is still high. These mixed salt tests prove that AO-PIM-1 still provides good selectivity for lithium extraction with Mg2+ / Li+ratio reduced evidently. The ionic composition of product solution after 8 hours of testing is shown in Fig. 10i, indicating that the mass ratio of Mg / Li could be significantly reduced from 65 to around 2, which allows further precipitation of the lithium to U2CO3 directly.

[0367] Example 31 : Electrodialysis separation performance of ether-free-backbone AO-PIM membranes

[0368] Another group of PIM membranes prepared by superacid-catalysed Friedel-Crafts reactions, including PIM-SBI-OH-CN and PIM-SBI-OMe-CN and modified polymers with amidoxime groups (PIM-SBI-OH- AO, and PIM-SBI-OMe-AO) were evaluated. PIM-SBI-OH-AO polymer demonstrated high monovalent ion permeation rates in electrodialysis (Fig. 11 a) as well as remarkable monovalent / divalent ion selectivity in binary mixtures, for example, K / Mg selectivity at 1850, Na / Mg selectivity at 1650, and Li / Mg selectivity about 485 (Fig. 11 b). The membrane maintained high ion selectivity in KCI / NaCI / LiCI / MgCh salt mixtures (Fig. 11 c). The control sample PIM-SBI-OMe-AO with methyl group protection showed much lower ion permeation rates and poor selectivity. In contrast, PIM-SBI-OMe-CN shows negligible selectivity and slow ion transport which is two orders of magnitude lower due to the hydrophobic nature.

[0369] Example 32: Electrodialysis separation performance of fluorinated AO-PIM membranes

[0370] In this example, the performance of electrodialysis with two kinds of membranes was investigated. The first one is one co-polymer PIM-SBI-OH-5F-AO with AO group and fluorinated contents to increase the stability of the membrane. Another one is SBI-OMe-AO with OH group was instituted by OMe group. Fig. 12 (a), (b) and (c) show the data of separation of binary salt solutions, with the concentration of K+and Mg2+, Na+and Mg2+, Li+and Mg2+in concentrate chamber as a function of time, respectively. The typical operation conditions and performance data are presented in Table 2. Similar to AO-PIM-1 , the A0-PIM-5F-0H membrane enable selective transport of monovalent ions while blocking large Mg ions. For AO-PIM-5F-OH, the membrane show high permeation rate for monovalent ions (K+: 0.153 mol nr2h1; Na+: 0.13 mol nr2h1; and Li+0.038 mol nr2h1), with a high selectivity for K / Mg (selectivity=632), Na / Mg (selectivity=338) and Li / Mg (selectivity=250).

[0371] Table 2. Summary of AO-PIM-5F-OH and SBI-OMe-AO for ion separation

[0372] Example 33: Electrodialysis separation performance of ether-functionalized PIM membranes

[0373] In this example, four PIM-EO membranes (PIM-EO, PIM-OMeo 67-EOo 33, PIM-OMeoss-EOo .17 and PIM- COOH067-EO033) were tested to explore Li / Mg separation. Fig. 13(a) and Fig. 13(b) show the concentration of Li+and Mg2+in concentrate chamber as a function of time. It can be seen from the figure that Li+concentration could increase to 2.07 mol / L with PIM-EO30 membrane, the increment was nearly twice of those for the other two membranes. While for PIM-OMei .0-EO0.5, the Li+concentration was much lower than that of the other three membranes. Fig. 13(c) shows permeation rate and selectivity of the four membranes for Li+and Mg2+separation. The typical operation conditions and performance data are presented in Table 3. Although PIM-EO exhibited a high Li+permeation rate, the Li / Mg selectivity for PIM-EO was the lowest (only 14) compared with the selectivity of other three membranes. PIM-OMeo 67-EOo 33 also showed low Li / Mg selectivity (only 24) due to its low permeation rate. As PIM-OMeo ss-EOo 17 and PIM-COOH067-EO033 have high Li+permeation rate and low Mg2+permeation rate, the selectivity of the two membranes for Li / Mg separation could reach 71 and 122, respectively.

[0374] Table 3. Summary of PIM-EO membranes for ion separation Example 34: Electrodialysis separation performance

[0375] To explore the effect of carboxylic acid group on Li and Mg separation, cPIM-1 and cPIM-1-OMe membranes were tested in electrodialysis system. Fig. 14(a) and 14(b) shows the Li+and Mg2+concentrations in concentrate chamber as a function of time for the two membranes. cPIM-1 with COOH group showed high Li+concentration up to 0.16 mol / L after 20 min operation, while effectively blocking the transport of Mg2+. After the carboxylic acid groups were protected with methyl group, the ion permeation rate decreased significantly. The permeation rate and selectivity of cPIM-1 and cPIM-1-OMe for Li+and Mg2+separation is shown in Fig. 14(c). The typical operation conditions and performance data are presented in Table 4. cPIM-1 demonstrated a high Li+permeation rate of 0.25 mol nr2h-1and Li / Mg selectivity over 400. In contrast, cPIM-1-OMe exhibited Li+permeation rate of 0.006 mol nr2h-1and negligible Li+ / Mg2+selectivity. This result shows that COOH groups play important roles in facilitating the transport of monovalent salt ions.

[0376] Table 4. Summary of cPIM-1 and cPIM-OMe membranes for ion separation

[0377] Example 35: Flow battery performance of ether-free AO-PIM membranes their application in aqueous organic flow batteries. SBI-OH and SBI-OMe were copolymerized and converted to amidoxime groups, to form a copolymer SBI-OH(x)-OMe-AO with varied ratio of functional groups (where x is the molar ratio of the OH groups in percentage, e.g. 50, 60, 70, 80). For the polymer SBI-OH-AO, the membrane shows high conductivity in KOH (up to 27 mS cm1) but low selectivity due to the deprotonation of the hydroxyl groups and swelling. After introducing comonomer with methyl group protection, the membranes still maintain high conductivity of 18 mS cm1at 30°C, and enhanced selectivity (Figure 15). The diffusivity of K4Fe(CN)e is below I O10cm2s1. The resulting membranes show low resistance in flow batteries and gives high power density (Figure 16).

[0378] Example 36: Synthesis of benzo-methanoanthracene (BzMA)

[0379] 15 g (160 mmol) of Norbornene, 10 g of Anthracene (56.2 mmol), and a magnetic stir bar were added to a 100 ml high-pressure reactor. The mixture was then heated to 235 °C, reaching a maximum pressure of 24 bars for 4 hours. Subsequently, the excess norbornene was removed by vacuum, and the resulting grey solid benzo-methanoanthracene (BzMA) was purified by column chromatography.

[0380] Example 37: Synthesis of PAP-BzMA

[0381] 2.84g (25.1 mmol) N-methyl-4-piperidone, 0.78 g (2.868 mmol) BzMA and 3.73 g (16.25 mmol) p- terphenyl (TP) were dissolved in 85.4ml (133.84 mmol) dichloromethane (DCM) using a three-neck round bottom flask with a magnetic stirrer bar at room temperature under N2 atmosphere. 1.8ml (23.9 mmol) trifluoracetic acid (TFA) and 22.6ml (256.23 mmol) trifluoromethanesulfonic acid (TFSA) were then added dropwise slowly at 0 °C. The solution turned dark blue after adding TFSA and was continuously stirred at 0 °C for 4-7 hours. When the solution became too viscous for the stirrer bar to rotate, it was slowly poured into room temperature ammonia solution while stirring overnight. The resulting white solid was washed three times with DI water until pH 7 and dried at 100 °C overnight.

[0382] A suspension of PAP-15BzMA-TP (1g) in DMSO (20 mL) was prepared in a flask, and the solution was stirred at room temperature for 30 minutes. Following that, K2CO3 (0.39 g) and iodomethane (1 mL) were added to the mixture, and the reaction was continuously stirred at room temperature for 24 hours in the absence of light. Ethyl acetate was then introduced to the resulting thick solution. The resulting light-yellow precipitate was filtered, washed three times with water, and subsequently dried in an oven at 80°C under vacuum for 24 hours.

[0383] Example 38: Synthesis of PAP-15EA

[0384] 2.84g (25.1 mmol) N-methyl-4-piperidone, 0.59 g (2.868 mmol) ethanoanthracene (EA) and 3.73 g (16.25 mmol) p-terphenyl (TP) were dissolved in 85.4ml (133.84 mmol) dichloromethane (DCM) using a three-neck round bottom flask with a magnetic stirrer bar at room temperature under N2 atmosphere. 1.8ml (23.9 mmol) trifluoracetic acid (TFA) and 22.6ml (256.23 mmol) trifluoromethanesulfonic acid (TFSA) were then added dropwise slowly at 0 °C. The solution turned dark blue after adding TFSA and was continuously stirred at 0 °C for 4-7 hours. When the solution became too viscous for the stirrer bar to rotate, it was slowly poured into room temperature ammonia solution while stirring overnight. The resulting white solid was washed three times with DI water until pH 7 and dried at 100 °C overnight.

[0385] A suspension of PAP-15EA (1g) in DMSO (20 mL) was prepared in a flask, and the solution was stirred at room temperature for 30 minutes. Following that, K2CO3 (0.39 g) and iodomethane (1 mL) were added to the mixture, and the reaction was continuously stirred at room temperature for 24 hours in the absence of light. Ethyl acetate was then introduced to the resulting thick solution. The resulting light-yellow precipitate was filtered, washed three times with water, and subsequently dried in an oven at 80°C under vacuum for 24 hours.

[0386] Example 39: Synthesis of PAP-15SBI-0Me

[0387] 2.84g (25.1 mmol) N-methyl-4-piperidone, 0.96 g (2.868 mmol) SBI-OMe and 3.73 g (16.25 mmol) p- terphenyl (TP) were dissolved in 85.4ml (133.84 mmol) dichloromethane (DCM) using a three-neck round bottom flask with a magnetic stirrer bar at room temperature under N2 atmosphere. 1.8ml (23.9 mmol) trifuoroacetic acid (TFA) and 22.6ml (256.23 mmol) trifluoromethanesulfonic acid (TFSA) were then added dropwise slowly at 0 °C. The solution turned dark blue after adding TFSA and was continuously stirred at 0 °C for 4-7 hours. When the solution became too viscous for the stirrer bar to rotate, it was slowly poured into room temperature ammonia solution while stirring overnight. The resulting white solid was washed three times with DI water until pH 7 and dried at 100 °C overnight.

[0388] A suspension of PAP-15SBI(-OMe)-TP (1g) in DMSO (20 mL) was prepared in a flask, and the solution was stirred at room temperature for 30 minutes. Following that, K2CO3 (0.39 g) and iodomethane (1 mL) were added to the mixture, and the reaction was continuously stirred at room temperature for 24 hours in the absence of light. Ethyl acetate was then introduced to the resulting thick solution. The resulting light-yellow precipitate was filtered, washed three times with water, and subsequently dried in an oven at 80°C under vacuum for 24 hours.

[0389] Example 40: Synthesis of BzMAfCLfg) High pressure

[0390] O+or Microwave

[0391] F F F F 200 °C, 4h

[0392] 1 H,1 H,2H-Nonafluorohex-1 -ene (22 g, 89.04 mmol), dicyclopentadiene (4.1 g, 31.01 mmol) and a magnetic stir bar were added into a 100 ml high-pressure reactor. The mixture was then heated to 200 °C, reaching a maximum pressure of 10 bar for 4 h (Finished at 1 bar). The resultant product in the form of yellow liquid oil was subjected to distillation under reduced pressure, and afford Norbornene-C4Fg. The distillation occurred at 78 °C, yielding a colorless liquid consisting of a mixture of endo / exo-isomers.

[0393] 32.9 g (80 mmol) of Norbornene-C4Fg, 5 g of Anthracene (23.1 mmol), and a magnetic stir bar were added to a 100 ml high-pressure reactor. The mixture was then heated to 235 °C, reaching a maximum pressure of 0 bars for 4 hours. Subsequently, the excess norbornene-CeFn was removed by vacuum, and the resulting grey solid was purified by column chromatography.

[0394] Example 41 : Synthesis of PAP-15BzMA(C4F9)-TP

[0395] 2.84g (25.1 mmol) N-methyl-4-piperidone, 1.41 g (2.868 mmol) BzMA(C4Fg) and 3.73 g (16.25 mmol) p-terphenyl (TP) were dissolved in 85.4ml (133.84 mmol) dichloromethane (DCM) using a three-neck round bottom flask with a magnetic stirrer bar at room temperature under N2 atmosphere. 1.8ml (23.9 mmol) trifluoracetic acid (TFA) and 22.6ml (256.23 mmol) trifluoromethanesulfonic acid (TFSA) were then added dropwise slowly at 0 °C. The solution turned dark blue after adding TFSA and was continuously stirred at 0 °C for 4-7 hours. When the solution became too viscous for the stirrer bar to rotate, it was slowly poured into room temperature ammonia solution while stirring overnight. The resulting white solid was washed three times with DI water until pH 7 and dried at 100 °C overnight.

[0396] A suspension of PAP-15BzMA(C4Fg)-TP (1 g) in DMSO (20 mL) was prepared in a flask, and the solution was stirred at room temperature for 30 minutes. Following that, K2CO3 (0.39 g) and iodomethane (1 mL) were added to the mixture, and the reaction was continuously stirred at room temperature for 24 hours in the absence of light. Ethyl acetate was then introduced to the resulting thick solution. The resulting light-yellow precipitate was filtered, washed three times with water, and subsequently dried in an oven at 80°C under vacuum for 24 hours.

[0397] Example 42: Membrane properties

[0398] The membrane properties, including ion exchange capacity, hydroxide conductivity, water uptake, swelling ratio, and mechanical properties were measured. The results are shown in Figure 17 and Table 6. Generally, the introduction of twisted backbone structures into conventional PAP polymer design led to formation of highly interconnected microporous water channels within the PIM-PAP membranes. Figure 17 shows the key properties of newly-developed membranes. Generally, the membranes with enhanced free volume showed higher water uptake and higher degree of swelling. The large and well- connected ionic channels are believed to promote the transport of hydroxide ions. Therefore, PAP- 15BzMA-TP reached a promising conductivity of 194.35 mS / cm at 80 °C, showing a 41 % improvement compared with the well-reported poly(terphenyl piperidinium) (PAP-TP). The optimized ratio for the PAP- BzMA-TP series AEM is in the range of 15%. Therefore, with the content of BzMA increasing to 20%, the conductivity starts to decrease. Due to the excessive water adsorption of the 45% BzMA copolymer in PAP-45BzMA AEM, it showed a lower hydroxide conductivity of 148.32 mS / cm at 80 °C. As shown in Table 3, these membranes generally show high mechanical strength.

[0399] Table 6. Summary of anion exchange membrane properties.

[0400] Figure 18 shows the typical hydroxide conductivity and hydration number as a function of the fraction of contorted monomer. Generally, the introduction of contorted PIM monomer enhances the hydroxide conductivity. However, as the water uptake and hydration number increases, the interchain distance increases which led to the decrease of hydroxide conductivity. The optimal ratio of contorted monomer is around 15%.

[0401] The addition of the BzMA(C4Fg) series fluorinated BzMA monomer can effectively enhance the phase separation of the AEM. When combined with the microporous structure, the fluorinated PAP- 15BzMA(C4Fg)-TP exhibits higher hydroxide conductivity.

[0402] Example 43: Anion exchange membrane water electrolyzer performance

[0403] AEM and ionomer with well-defined mass transport pathway and high ion-conductivity by using ether- free PIM-PAP series ionic microporous polymers. The high conductivity and mass transport can be attributed to the highly interconnected channels and water-clusters formed within the hydrophilic micropores of high free volume. The electrochemical performance of such ion-conductivity microporous membranes was evaluated in a laboratory anion exchange membrane water electrolyzer.

[0404] Firstly, the water electrolysis performance of commercially available PAP-TP-85 AEM and PAP-BP-60 ionomers, developed by Versogen (USA) were verified. As shown in Figure 19, the commercial PAP membranes showed great performance, reaching 4 A cm2at 80 °C and exhibiting very low resistance, around 0.054 Ohm cm2. Compared to commercial PAP membranes, our PAP-15BzMA-TP AEM membrane could reach a higher current density of 7.5 A cm2at 80 °C under the same conditions, which is superior to that of the commercial PAP membranes. With higher loading of contorted monomers in the AEM membrane, the electrolyser performance is slightly weakened due to the lower hydroxide conductivity. The electrolyser performance can be further enhanced by reducing the membrane thickness. With the membrane thickness decreased from 65 to 15 pm, the current density can be enhanced from 4 to 11 .27 A cm-2. Furthermore, the electrolysis performance in varied KOH concentration was also tested. The high-conductivity membrane enabled the high performance of electrolyser at low concentration of KOH. Durability tests suggest that the electrolyser can be operated stable for about 400 h. These results demonstrate great potential of newly developed polymer membranes to further improve the performance in energy conversion and storage. Furthermore, these polymers can also be used as ionomers for catalysts binders.

[0405] References

[0406] 1. Wang, A., etal., Ion-Selective Microporous Polymer Membranes with Hydrogen-Bond and Salt-Bridge Networks for Aqueous Organic Redox Flow Batteries. Adv. Mater. 2023, 35, 2210098. https: / / doi.Org / 10.1002 / adma.202210098

[0407] Aspects of the present invention are set out in the following numbered clauses.

[0408] 1 . A polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising a carboxylic acid and an oxadiazole moiety; wherein the or each side group is attached to the polymeric backbone by said oxadiazole moiety.

[0409] 2. The polymer according to clause 1 , wherein each contorted aromatic moiety comprises a ring system with at least two aromatic rings, for example at least three aromatic rings, such as at least four aromatic rings or at least five aromatic rings, optionally wherein the ring system includes one or more heteroatoms. 3. The polymer according to clause 2, wherein the at least two aromatic rings are phenyl rings, for example at least three phenyl rings, such as at least four phenyl rings or at least five phenyl rings.

[0410] 4. The polymer according to any preceding clause wherein each contorted aromatic moiety comprises about 10 to 100 carbon atoms, optionally about 10 to 75 carbon atoms, optionally about 10 to 50 carbon atoms.

[0411] 5. The polymer according to any one of clauses 2 to 4, wherein the at least two aromatic rings are connected by:

[0412] (a) a spiro system;

[0413] (b) a fused ring system;

[0414] (c) a bridged ring system; or

[0415] (d) a single bond and / or a double bond; or a combination thereof.

[0416] 6. The polymer according to clause 5, wherein the at least two aromatic rings are connected by a spiro system as follows, which may be optionally substituted:

[0417] 7. The polymer according to clause 5, wherein the at least two aromatic rings are connected by a fused ring system, wherein the fused ring system comprises one ring fused to said at least two aromatic rings, such as an optionally substituted cyclopentane.

[0418] 8. The polymer according to clause 5, wherein the at least two aromatic rings are connected by a bridged ring system, wherein the bridged ring system is carbocyclic, such as one of the following, which may be optionally substituted: or heterocyclic (e.g. heterocyclic equivalents of the aforementioned carbocyclic rings, comprising one or more heteroatoms), optionally comprising one or more (e.g. two) nitrogen atoms, such as the following, which may be optionally substituted: optionally wherein the bridged ring system is fused to said at least two aromatic rings.

[0419] 9. The polymer according to any preceding clause wherein each contorted aromatic moiety is independently selected from the following, which may be optionally substituted:

[0420] wherein the block dots indicate possible attachment points in the polymeric backbone.

[0421] 10. The polymer according to clause 5, wherein each contorted aromatic moiety is optionally substituted: wherein Ri, R2, R3 and R4 are each independently selected from hydrogen, C1-10 alkyl, C1-10 alkenyl or Ce-i4 aryl, optionally wherein R1, R2, R3 and R4 are each independently selected from H, CH3 or tert-butyl; or optionally wherein R1 and R2 and / or R3 and R4 are taken, together with the intervening atoms to which they are attached, to independently form a ring (e.g. a 6 membered ring, optionally aromatic, optionally fused to one or more additional rings which are optionally aromatic), optionally wherein R1and R2and / or R3and R4are taken, together with the intervening atoms to which they are attached, to independently form (i.e., to form benzene) and / or

[0422] 11. The polymer according clause 5, wherein each contorted aromatic moiety is optionally substituted:

[0423] (cCA5’) wherein R5 and Re are each independently hydrogen or C1-3 alkyl, optionally CH3.

[0424] 12. The polymer according to clause 5, wherein each contorted aromatic moiety is optionally substituted: wherein R7 and Rs are each independently selected from hydrogen or C1-10 haloalkyl, optionally fluoroalkyl such as (CF2)nCF3 wherein n is from 1 to 9, such as 1 , 3, 5 or 7 or wherein R7 and Rs are taken, together with the intervening atoms to which they are attached, to form a perfluorinated ring, optionally a six membered ring,

[0425] E V F Fnxr-FF-CH HC-F optionally wherein R7and R8are taken together to form 13. The polymer according to clause 5, wherein each contorted aromatic moiety is optionally substituted: wherein R9, R10, R11 and R12 are each independently selected from hydrogen, fluorine, phenyl, C1-15 alkyl, C1-15 haloalky I , C1-15 alkenyl or C1-15 haloalkenyl; optionally wherein R9 and R10 are each independently selected from hydrogen or fluorine, or optionally wherein R9 and R10 are taken, together with the intervening atoms to which they are attached, to form optionally substituted with one or more electron withdrawing groups, such as a trihalogenated methyl group, e.g. CF3 groups, such as optionally wherein Rn and R12 are each independently selected from hydrogen, fluorine, phenyl or C1-5 alkyl, such as methyl, ethyl or isopropyl; optionally wherein Rn and R12 are both the same.

[0426] 14. The polymer according to clause 5, wherein each contorted aromatic moiety is optionally substituted:

[0427] (cCA8’) wherein Rn and R14 are each independently selected from hydrogen, C1-10 alkyl or C1-10 haloalkyl, optionally wherein R13 and R14 are each independently selected from hydrogen or (CH2)n(CH3) wherein n is from 1 to 9, for example 1 , 3, 5 or 7, optionally substituted with one or more fluoro atoms, for example (CF2)nCF3 wherein n is from 1 to 9, for example 1 , 5 or 7; optionally wherein R13 and R14 are the same or wherein R13 and R14 are taken together to form

[0428] 15. The polymer according to clause 5, wherein each contorted aromatic moiety is optionally substituted:

[0429] (cCA1 T) wherein R15, R16, R17 and Ris are each independently selected from hydrogen or C1-10 alkyl, such as C1- 5 alkyl, for example methyl, ethyl or isopropyl optionally wherein R15, R16, R17 and Ris are the same.

[0430] 16. The polymer according to any preceding clause, wherein contorted aromatic moieties are linked by a linker moiety to form the backbone.

[0431] 17. The polymer according to any preceding clause, wherein the backbone is adapted to prevent free rotation of each contorted aromatic moiety relative to said backbone, optionally wherein the linker moiety of clause 16 is adapted to prevent free rotation of each contorted aromatic moiety relative to the said backbone (e.g. wherein the linker moiety bonds to at least two locations on each contorted aromatic moiety).

[0432] 18. The polymer according to clause 16 or clause 17, wherein the or each side group is attached by the oxadiazole moiety to:

[0433] (a) the or each contorted aromatic moiety; or (b) the linker moiety.

[0434] 19. The polymer according to any one of clauses 16 to 18, wherein the polymer is of formula: wherein:

[0435] CA is said contorted aromatic moiety,

[0436] Li is said linker moiety, each Si or S2 is independently said side group or hydrogen, nitrile, amine, amide, carboxylic acid or amidoxime; with the proviso that at least one of Si and S2 is said side group, and n is at least 2 (optionally at least 100).

[0437] 20. The polymer according to any preceding clause, wherein the polymer comprises a repeat unit of molecular weight of from about 500 to about 1500 g mol1, such as from about 700 to about 1000 g mol1. 21 . The polymer according to clause 19 or clause 20, wherein each Si or S2 is independently 'nM / , or hydrogen, nitrile, amine, amide, carboxylic acid or amidoxime; and wherein R is an aliphatic or aromatic carboxylic acid group.

[0438] 22. The polymer according to any one of clauses 19 to 21 , wherein Li comprises an optionally substituted phenyl group.

[0439] 23. The polymer according to any of clauses 19 to 22, wherein Li is optionally substituted:

[0440] 24. The polymer according to any one of clauses 19 to 23, wherein the polymer is of formula:

[0441] 25. The polymer according to any one of clauses 21 to 24, wherein the or each R is independently:

[0442] (a) a monocarboxylic acid of formula Y-COOH, wherein Y is an alkyl (optionally interrupted by one or more oxygen atoms), haloalkyl (optionally a fluoroalkyl) or aryl group (such as comprising one phenyl group or two or more phenyl groups).

[0443] (b) a dicarboxylic acid of formula HOOC-Y’-COOH, wherein Y’ is an aryl group.

[0444] 26. The polymer according to any of one of clauses 21 to 25, wherein the or each R is independently selected from:

[0445] COOH COOH wherein m is 2, 3 or 4 wherein R19, R20, R21 and R22 are each independently H or F mer according to any preceding clause, wherein the polymer is of formula: wherein n is at least 2 (optionally at least 100). 28. The polymer according to any one of clauses 1 to 26, wherein the polymer is of formula: wherein n is at least 2 (optionally at least 100).

[0446] 29. The polymer according to any one of clauses 1 to 26, wherein the polymer is of formula: wherein n is at least 2 (optionally at least 100).

[0447] 30. A method of preparing a polymer (such as a polymer of intrinsic microporosity) comprising

[0448] (a) providing a precursor polymer comprising a polymeric backbone comprising contorted aromatic moieties (optionally as defined in any preceding clause); and at least one side group comprising an amidoxime.

[0449] (b) adding the precursor to an anhydride or adding the anhydride to the precursor.

[0450] 31 . The method according to clause 30, wherein said adding is in the presence of an alkali reagent.

[0451] 32. The method according to clause 30 or clause 31 , wherein the alkali reagent is selected from a hydroxide or an ethoxide; optionally a sodium or potassium hydroxide or ethoxide; or mixtures thereof 33. The method according to clause 31 or 32, wherein the anhydride and the alkali reagent are at a molar ratio from about 1 :1 to about 1 :3, such as from about 1 :1 to about 1 :2, or about 1 :2 to about 1 :3, preferably about 1 :2 to about 1 :2.5.

[0452] 34. The method according to any one of clauses 30 to 33, wherein the anhydride and the precursor polymer are provided at a molar ratio of from about 2:1 to about 12:1 , such as from about 2:1 to about 6:1 , or from about 2:1 to about 8:1 , for example about 2:1 to about 10:1 , preferably about 4:1 to about 6:1.

[0453] 35. The method according to any one of clauses 30 to 34, further comprising adjusting to a pH of from 1 to 2 after said (b).

[0454] 36. The method according to any one of clauses 30 to 35, wherein the precursor polymer is of formula: wherein CA is a contorted aromatic moiety;

[0455] Li is a linker moiety;

[0456] S3 is hydrogen or said side group and n is at least 2 (optionally at least 100).

[0457] 37. The method according to any one of clauses 30 to 36, wherein the anhydride is a cyclic anhydride, optionally comprising a ring having at least 5 ring atoms, optionally at least 6 ring atoms, optionally at least 7 ring atoms;, optionally wherein the anhydride comprises one or more moieties of formula , which may be optionally substituted in the ring thereof to replace a carbon with one or more heteroatoms, such as oxygen.

[0458] 38. The method according to any one of clauses 30 to 37, wherein the anhydride comprises at least one phenyl group, such as two phenyl groups or three phenyl groups, for example four phenyl groups or five phenyl groups (e.g. pendant or fused to the remainder of the anhydride).

[0459] 39. The method according to any one of clauses 30 to 38, wherein the anhydride is optionally substituted with one or more halogens, for example fluorine.

[0460] 40. The method according to any one of clauses 30 to 39 wherein the anhydride is selected from one of the following, which may be optionally substituted

[0461]

[0462] 41 . A polymer (such as a polymer of intrinsic microporosity) obtained or obtainable by the method according to any one of clauses 30 to 40.

[0463] 42. An ion-exchange membrane or resin comprising a polymer (such as a polymer of intrinsic microporosity) according to any one of clauses 1 to 29 or 41 .

[0464] 43. Use of a polymer (such as a polymer of intrinsic microporosity) according to any one of clauses 1 to 29 or clause 41 in an ion-exchange membrane or resin.

[0465] 44. An ion-exchange membrane comprising a polymer (such as a polymer of intrinsic microporosity) comprising a backbone comprising contorted aromatic moieties; and at least one side group comprising a phosphonic acid and a perfluorinated phenyl group; wherein the or each side group is attached to the backbone by said perfluorinated phenyl group.

[0466] 45. The ion-exchange membrane according to clause 44, wherein the polymer is a copolymer of formula: wherein CA is a contorted aromatic moiety, wherein Si is a side group comprising a perfluorinated phenyl substituted with a phosphonic acid, wherein each of RT, R2 and R3 are independently hydrogen or optionally substituted alkyl, haloalkyl, aryl or haloaryl (e.g. optionally wherein the aryl is bicyclic); optionally wherein each R3 is independently a perfluorinated phenyl; wherein m is from 0 to 1000 (preferably from 100 to 500) and wherein n is from 0 to 1000 (preferably from 100 to 500).

[0467] 46. The ion-exchange membrane according to clause 45, wherein Rr is hydrogen or a C1-10 haloalkyl group, optionally CF3.

[0468] 47. The ion-exchange membrane according to clause 45 or clause 46, wherein R2 is hydrogen or a C1-10 haloalkyl group, optionally CF3.

[0469] 48. The ion-exchange membrane according to any one of clauses 45 to 47, wherein R3 is optionally substituted C1-10 alkyl, C1-10 haloaryl or Ce-2o aryl, e.g. perfluorinated phenyl . 49. The ion-exchange membrane of clause 48, wherein R3 is selected from optionally substituted:

[0470] 50. The ion-exchange membrane according to any one of clauses 45 to 49, wherein Si is

[0471] 51. The ion-exchange membrane according to any of clauses 44 to 50, wherein each contorted aromatic moiety comprises a ring system with at least two aromatic rings, for example at least three aromatic rings, such as at least four aromatic rings or at least five aromatic rings, optionally wherein the ring system includes one or more heteroatoms.

[0472] 52. The ion-exchange membrane according to clause 51 , wherein the at least two aromatic rings are phenyl rings, for example at least three phenyl rings, such as at least four phenyl rings or at least five phenyl rings.

[0473] 53. The ion-exchange membrane according to any of clauses 44 to 52, wherein each contorted aromatic moiety comprises about 10 to 100 carbon atoms, optionally about 10 to 75 carbon atoms, optionally about 10 to 50 carbon atoms.

[0474] 54. The ion-exchange membrane according to any one of clauses 51 to 53, wherein the at least two aromatic rings are connected by:

[0475] (a) a spiro system;

[0476] (b) a fused ring system;

[0477] (c) a bridged ring system; or

[0478] (d) a single bond and / or double bond. or a combination thereof.

[0479] 55. The ion-exchange membrane according to clause 54, wherein the at least two aromatic rings are connected by a spiro system as follows, which may be optionally substituted:

[0480] 56. The ion-exchange membrane according to clause 54, wherein the at least two aromatic rings are connected by a fused ring system, wherein the fused ring system comprises one ring fused to said at least two aromatic rings, such as an optionally substituted cyclopentane.

[0481] 57. The ion-exchange membrane according to clause 54, wherein the at least two aromatic rings are connected by a bridged ring system, wherein the bridged ring system is carbocyclic, such as one of the following, which may be optionally substituted: or heterocyclic (e.g. heterocyclic equivalents of the aforementioned carbocyclic rings, comprising one or more heteroatoms), optionally comprising one or more nitrogen atoms (e.g. two), such as the following, which may be optionally substituted: optionally wherein the bridged ring system is fused to said at least two aromatic rings.

[0482] 58. The ion-exchange membrane according to any one of clauses 44 to 57, wherein each contorted aromatic moiety comprises one of the following, which may be optionally substituted:

[0483] wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0484] 59. The ion-exchange membrane according to clause 54, wherein each contorted aromatic moiety is optionally substituted: wherein R1, R2, R3 and R4are each independently selected from hydrogen, C1-10 alkyl, C1-10 alkenyl or Ce-i4 aryl, optionally wherein R1, R2, R3 and R4are each independently selected from:

[0485] H, CH3 or tert-butyl; or optionally wherein R1 and R2 and / or R3 and R4are taken, together with the intervening atoms to which they are attached, to independently form a ring (e.g. a 6 membered ring, optionally aromatic, optionally fused to one or more additional rings which are optionally aromatic), optionally wherein R1and R2and / or R3and R4are taken together with the intervening atoms to which they are attached, to independently form (i.e., to form benzene) and / or wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0486] 60. The ion-exchange membrane according clause 54, wherein each contorted aromatic moiety is optionally substituted: wherein R5 and Ra are each independently hydrogen or C1-3 alkyl, optionally CH3; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0487] 61 . The ion-exchange membrane according to clause 54, wherein each contorted aromatic moiety is optionally substituted: wherein R7 and Ra are each independently selected from hydrogen or C1-10 haloalkyl, optionally fluoroalkyl such as (CF2)nCF3 wherein n is from 1 to 9, such as 1 , 3, 5 or 7 or wherein R7 and Ra are taken, together with the intervening atoms to which they are attached, to form a perfluorinated ring, optionally a six membered ring,

[0488] E V F

[0489] Fn r~FF-CH HC-F optionally wherein R7and R8are taken together to form ; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0490] 62. The ion-exchange membrane according to clause 54, wherein each contorted aromatic moiety is optionally substituted: wherein R9, R10, R11 and R12 are each independently selected from hydrogen, fluorine, phenyl, C1-15 alkyl, C1-15 haloalky I , C1-15 alkenyl or C1-15 haloalkenyl; optionally wherein R9 and R10 are each independently selected from hydrogen or fluorine, or optionally wherein R9 and R10 are taken, together with the intervening atoms to which they are attached, to form optionally substituted with one or more electron withdrawing groups, such as a trihalogenated methyl group, e.g. CF3 groups, such as optionally wherein Rn and R12 are each independently selected from hydrogen, fluorine, phenyl or C1-5 alkyl, such as methyl, ethyl or isopropyl; optionally wherein Rn and R12 are both the same; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0491] 63. The ion-exchange membrane according to clause 54, wherein each contorted aromatic moiety is optionally substituted: wherein Rn and R14 are each independently selected from hydrogen, C1-10 alkyl or C1-10 haloalkyl, optionally wherein R13 and R14 are each independently selected from hydrogen or (CH2)n(CH3) wherein n is from 1 to 9, for example 1 , 3, 5 or 7, optionally substituted with one or more fluoro atoms, for example (CF2)nCF3 wherein n is from 1 to 9, for example 1 , 5 or 7; optionally wherein R13 and R14 are the same or wherein R13 and R14 are taken together to form wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0492] 64. The ion-exchange membrane according to clause 54, wherein each contorted aromatic moiety is optionally substituted:

[0493] (pCA11’) wherein R15, R16, R17 and Ris are each independently selected from hydrogen or C1-10 alkyl, such as C1-

[0494] 5 alkyl, for example methyl, ethyl or isopropyl. optionally wherein R15, R16, R17 and Ris are the same; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0495] 65. The ion-exchange membrane according to any one of clauses 44 to 64, wherein contorted aromatic moieties are linked by a linker moiety to form the backbone.

[0496] 66. The ion-exchange membrane according to any one of clauses 44 to 65, wherein the backbone is adapted to prevent free rotation of each contorted aromatic moiety relative to said backbone, optionally wherein the linker moiety of clause 65 is adapted to prevent free rotation of each contorted aromatic moiety relative to the said backbone (e.g. wherein the linker moiety bonds to at least two locations on each contorted aromatic moiety).

[0497] 67. The ion-exchange membrane according to clause 65 or clause 66, wherein the or each side group is attached by the perfluorinated phenyl group to:

[0498] (a) the or each contorted aromatic moiety; or (b) the linker moiety.

[0499] 68. The ion-exchange membrane according to any one of clauses 65 to 67, wherein the linker moiety is a single bond or .

[0500] 69. The ion-exchange membrane according to any one of clauses 44 to 54 or 65 to 68, wherein the polymer is of formula:

[0501] 70. The ion-exchange membrane according to any one of clauses 44 to 69, wherein the polymer is obtained by addition of a suitable phosphonated polymer precursor to tri(trimethylsilyl)phosphite or by addition of tri(trimethylsilyl)phosphite to a suitable phosphonated polymer precursor.

[0502] 71. The ion-exchange membrane according to clause 70, wherein polymer precursor is of formula

[0503] 72. The ion-exchange membrane according to any one of clauses 44 to 71 , wherein the polymer comprises at least one repeat unit of molecular weight of from about 400 to about 1500 g mol1, such as from about 600 to about 1000 g mol1. 73. A battery, comprising an anode and a cathode; wherein the anode and cathode are separated by an ion-exchange membrane according to clause 42 or any one of clauses 44 to 72.

[0504] 74. A kit of parts for a battery, wherein the kit comprises an anode, a cathode, and an ion-exchange membrane according to clause 42 or any one of clauses 44 to 72.

[0505] 75. A polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising wherein R is an aliphatic or aromatic carboxylic acid group; wherein p is from 1 to 100; wherein Gi is C(NH2)=NOH; C(=O)OH or S(=O)2OH;

[0506] 76. The polymer according to clause 75, wherein

[0507] (a) each contorted aromatic moiety is as defined by any of clauses 2 to 15; and / or

[0508] (b) the polymeric backbone is as defined according to clauses 16 or 17;

[0509] (c) R is as defined according to clauses 25 to 26.

[0510] 77. The polymer according to clause 75 or clause 76, wherein:

[0511] (a) each side group is between an adjacent pair of contorted aromatic moieties and collectively these form the backbone, optionally wherein each side group bonds twice to an adjacent contorted aromatic moiety (e.g. which, when taken together with the atoms on the contorted aromatic moiety to which the side group is bonded, forms a ring); or

[0512] (b) the side group is pendant to the polymeric backbone; and / or

[0513] (c) each side group bonds twice to an adjacent contorted aromatic moiety (e.g. which, when taken together with the atoms on the contorted aromatic moiety to which the side group is bonded, forms a ring).

[0514] 78. The polymer according to any one of clauses 75 to 77, wherein the polymer is a copolymer of formula: or wherein each of CAi and CA2 are each independently a contorted aromatic moiety (which may be the same or different), or a linear aromatic moiety (which may be the same or different), wherein Sia is said side group, wherein said side group may be bonded by one bond or two bonds; wherein each of Ria, R2a and Rsa are each independently hydrogen or optionally substituted alkyl, haloalkyl, optionally substituted aryl or haloaryl (e.g. optionally wherein the aryl is bicyclic); optionally wherein each Rsa is independently a perfluorinated phenyl or 2,4-di trifluoromethyl phenyl; or wherein Ria is absent, wherein m is from 0 to 1000 (preferably from 100 to 500) and wherein n is from 0 to 1000 (preferably from 100 to 500); wherein at least one of m and n is 1 ; and wherein the sum of m and n is at least 10, optionally at least 200, optionally at least 500, such as at least 800, optionally at least 1000; wherein when said group is connected to the polymeric backbone by two bonds (optionally to form a ring), Ria is absent.

[0515] Clause 79. The polymer according to any one of clauses 75 to 77, wherein the polymer is a copolymer of formula: wherein A1 is an aromatic group comprising at least one phenyl group, such as two or three phenyl groups; wherein CA1 is a contorted aromatic moiety; wherein each of Sia and S2a are each independently said side groups (which may be the same or different); wherein said side groups may be bonded by one bond or two bonds; wherein Ria and R2a are each independently absent, hydrogen or optionally substituted alkyl, haloalkyl, optionally substituted aryl or haloaryl (e.g. optionally wherein the aryl is bicyclic); wherein m is from 1 to 1000 (preferably from 100 to 500); wherein n is from 1 to 1000 (preferably from 100 to 500); wherein the sum of m and n is at least 10, optionally at least 200, optionally at least 500, such as at least 800, optionally at least 1000; wherein when said side group bonds twice to an adjacent contorted aromatic moiety (optionally to form a ring), Ria is absent.

[0516] 80. The polymer according to any one of clauses 75 to 79, wherein each contorted aromatic comprises a pendant moiety (substituting any available hydrogen), wherein the pendant moiety is:

[0517] (a) fluorinated alkyl, optionally (CF2)3CFs; and / or

[0518] (b) alkoxy, optionally OCH3; and / or

[0519] (c) hydroxyl.

[0520] 81. The polymer according to any one of clauses 78 to 80, wherein Ria is hydrogen or a C1-10 haloalkyl group, optionally CF3.

[0521] 82. The polymer according to any one of clauses 78 to 81 , wherein R2a is hydrogen or a C1-10 haloalkyl group, optionally CF3. 83. The polymer according to any one of clauses 78 to 82, wherein Rsa is optionally substituted Ci- 10 alkyl, C1-10 haloaryl or optionally substituted C6-20 aryl, e.g. perfluorinated phenyl or 2,4-di trifluoromethyl phenyl.

[0522] 84. The polymer of clause 83, wherein Rsa is selected from optionally substituted:

[0523] 85. The polymer according to any one of clauses 75 to 84, wherein each contorted aromatic moiety comprises a ring system with at least two aromatic rings, for example at least three aromatic rings, such as at least four aromatic rings or at least five aromatic rings, optionally wherein the ring system includes one or more heteroatoms.

[0524] 86. The polymer according to clause 85, wherein the at least two aromatic rings are phenyl rings, for example at least three phenyl rings, such as at least four phenyl rings or at least five phenyl rings.

[0525] 87. The polymer according to any of one clauses 75 to 87, wherein each contorted aromatic moiety comprises about 10 to 100 carbon atoms, optionally about 10 to 75 carbon atoms, optionally about 10 to 50 carbon atoms.

[0526] 88. The polymer according to any one of clauses 85 to 87, wherein the at least two aromatic rings are connected by:

[0527] (a) a spiro system;

[0528] (b) a fused ring system;

[0529] (c) a bridged ring system; or

[0530] (d) a single bond and / or double bond. or a combination thereof.

[0531] 89. The polymer according to clause 88, wherein the at least two aromatic rings are connected by a spiro system as follows, which may be optionally substituted:

[0532] 90. The polymer according to clause 88, wherein the at least two aromatic rings are connected by a fused ring system, wherein the fused ring system comprises one ring fused to said at least two aromatic rings, such as an optionally substituted cyclopentane.

[0533] 91 . The polymer according to clause 88, wherein the at least two aromatic rings are connected by a bridged ring system, wherein the bridged ring system is carbocyclic, such as one of the following, which may be optionally substituted: or heterocyclic (e.g. heterocyclic equivalents of the aforementioned carbocyclic rings, comprising one or more heteroatoms), optionally comprising one or more nitrogen atoms (e.g. two), such as the following, which may be optionally substituted: optionally wherein the bridged ring system is fused to said at least two aromatic rings.

[0534] 92. The polymer according to any one of clauses 75 to 91 , wherein each contorted aromatic moiety comprises one of the following, which may be optionally substituted:

[0535] wherein the attachment point may be any suitable substitution of H on the aromatic ring system, and optionally, as shown by the black dots; wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0536] 93. The polymer according to any one of clauses 75 to 91 , wherein each contorted aromatic moiety comprises one of the following, which may be optionally substituted:

[0537]

[0538] wherein each R29 is independently selected from wherein n is from 1 to 20. and wherein the attachment point may be any suitable substitution of hydrogen on the aromatic ring system.

[0539] 94. The polymer according to any one of clauses 75 to 93; wherein the polymeric backbone further comprises an aromatic group, optionally wherein the polymeric backbone further comprises one or more of the following: wherein the attachment point may be any suitable substitution of H on the aromatic ring system.

[0540] 95. The polymer according to clause 92, wherein each contorted aromatic moiety is optionally substituted: wherein Ri, R2, R3 and R4are each independently selected from hydrogen, C1-10 alkyl, C1-10 alkenyl or Ce-i4aryl, optionally wherein R1, R2, R3 and R4are each independently selected from:

[0541] H, CH3 or tert-butyl; or optionally wherein Ri and R2 and / or R3 and R4 are taken, together with the intervening atoms to which they are attached, to independently form a ring (e.g. a 6 membered ring, optionally aromatic, optionally fused to one or more additional rings which are optionally aromatic), 0 optionally wherein R1and R2and / or R3and R4are taken, together with the intervening atoms to which they are attached, to independently form (i.e., to form benzene) and / or wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0542] 96. The polymer according clause 92, wherein each contorted aromatic moiety is optionally substituted: wherein R5 and Re are each independently hydrogen or C1-3 alkyl, optionally CH3; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0543] 97. The polymer according to clause 92, wherein each contorted aromatic moiety is optionally substituted: wherein R7 and Rs are each independently selected from hydrogen or C1-10 haloalkyl, optionally fluoroalkyl such as (CF2)nCF3 wherein n is from 0 to 9, such as 1 , 3, 5 or 7 or wherein R7 and Rs are taken, together with the intervening atoms to which they are attached, to form a perfluorinated ring, optionally a six membered ring, optionally wherein R7and R8are taken together to form wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3). 98. The polymer according to clause 92, wherein each contorted aromatic moiety is optionally substituted: wherein R9, R10, R11 and R12 are each independently selected from hydrogen, fluorine, phenyl, C1-15 alkyl, C1-15 haloalkyl, C1-15 alkenyl or C1-15 haloalkenyl; optionally wherein R9 and R10 are each independently selected from hydrogen or fluorine, or optionally wherein R9 and R10 are taken, together with the intervening atoms to which they optionally substituted with one or more electron withdrawing groups, such as a trihalogenated methyl group, e.g. CF3 groups, and / or such as optionally wherein Rn and R12 are each independently selected from hydrogen, fluorine, phenyl or C1-5 alkyl, such as methyl, ethyl or isopropyl; optionally wherein Rn and R12 are both the same; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0544] 99. The polymer according to clause 92, wherein each contorted aromatic moiety is optionally substituted: wherein Rn and R14 are each independently selected from hydrogen, C1-10 alkyl or C1-10 haloalkyl, optionally wherein R13 and R14 are each independently selected from hydrogen or (CH2)n(CH3) wherein n is from 1 to 9, for example 1 , 3, 5 or 7, optionally substituted with one or more fluoro atoms, for example (CF2)nCF3 wherein n is from 1 to 9, for example 1 , 5 or 7; optionally wherein Rn and Ri4 are the same or wherein Rn and Ri4 are taken together to form wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0545] 100. The polymer according to clause 92, wherein each contorted aromatic moiety is optionally substituted: wherein R15, R16, R17 and Ria are each independently selected from hydrogen or C1-10 alkyl, such as C1- 5 alkyl, for example methyl, ethyl or isopropyl. optionally wherein R15, R16, R17 and Ria are the same; and wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).

[0546] 101 . The polymer according to any one of clauses 75 to 100, wherein the contorted aromatic moieties are linked by a linker moiety to form the backbone.

[0547] 102. The polymer according to any one of clauses 75 to 101 , wherein the backbone is adapted to prevent free rotation of each contorted aromatic moiety relative to said backbone, optionally wherein the linker moiety of clause 101 is adapted to prevent free rotation of each contorted aromatic moiety relative to the said backbone (e.g. wherein the linker moiety bonds to at least two locations on each contorted aromatic moiety).

[0548] 103. The polymer according to clause 101 or clause 102, wherein the or each side group is attached to:

[0549] (a) the or each contorted aromatic moiety; or

[0550] (b) the linker moiety; or

[0551] (c) the aromatic group as defined in clause 94.

[0552] 104. The polymer according to any one of clauses 101 to 103, wherein the linker moiety comprises an optionally substituted phenyl group or heteroaryl group, optionally wherein the linker moiety is optionally substituted: optionall wherein each Si is independently said side group, optionally wherein Si is wherein p is from 1 to 100. 105. The polymer according to any one of clauses 101 to 103, wherein the linker moiety is a single bond or alkoxy, preferably wherein the linker moiety is a single bond.

[0553] 106. The polymer according to any one of clauses 75 to 105 wherein the polymeric backbone comprises a continuous main chain: of carbon atoms, and / or which is substantially ether free, and / or which does not comprise C-O-C moieties.

[0554] 107. The polymer according to any one of clauses 78 or 80 to 106, wherein:

[0555] (a) CA1 and CA2 are the same; or

[0556] (b) CA1 and CA2 are different.

[0557] 108. The polymer according to any one of clauses 78 or 80 to 107, wherein each contorted aromatic moiety comprises:

[0558] 109. The polymer according to any one of clauses 78 or 80 to 107, wherein the contorted aromatic moiety comprises (e.g. optionally wherein one of CA1 or CA2 comprises):

[0559] 110. The polymer according to any of clauses 75 to 108, wherein the polymer is of formula wherein m is from 1 to 1000 (preferably from 100 to 500); wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500); wherein p is from 1 to 100. The polymer according to any of clauses 75 to 108, wherein the polymer is of formula

[0560] wherein n is from 1 to 1000 (preferably from 100 to 500); wherein m is from 1 to 1000 (preferably from 100 to 500); wherein x is from 1 to 1000 (preferably from 100 to 500) and wherein y is from 1 to 1000 (preferably from 100 to 500).

[0561] 112. The polymer according to any of clauses 75 to 109, wherein the polymeric backbone comprises a hydrocarbon core (such as an aromatic hydrocarbon core) with the remainder of the polymeric backbone pendant therefrom, optionally wherein the hydrocarbon core comprises a contorted aromatic moiety and / or wherein the hydrocarbon core comprises one of the following, which may be optionally substituted:

[0562] wherein the remainder of the polymeric backbone is pendant and substitutes any available hydrogen; and optionally, wherein the optional substituents of the hydrocarbon core may comprise one or more contorted aromatic moieties and / or side groups as defined in any of clauses 75 to 111 . The polymer according to any one of clauses 75 to 112 of formula

[0563] wherein n is from 1 to 1000 (preferably from 100 to 500); wherein m is from 1 to 1000 (preferably from 100 to 500); wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500).

[0564] 114. The polymer according to any of clauses 75 to 112 of formula

[0565] wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500).

[0566] 115. A polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising wherein the or each side group is attached to the polymeric backbone; and wherein the polymeric backbone further comprises moiety pendant therefrom (optionally wherein said moiety is between adjacent contorted aromatic moieties), where R1-R5 are optionally substituted by hydrogen, fluoride, and CF3.

[0567] 116. The polymer according to clause 115, wherein each contorted aromatic moiety is as defined in any of clauses 2 to 15, 80, 85 to 93 and 95 to 101 .

[0568] 117. The polymer according to clause 115 or clause 116, which is of formula

[0569] wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500).

[0570] 118. An ion-exchange membrane comprising the polymer according to any of clauses 75 to 117.

[0571] 119. Use of an ion-exchange membrane according to clause 118 in electrodialysis.

[0572] 120. Use of an ion-exchange membrane according to clause 118 in a redox flow battery.

[0573] 121. Use of an ion-exchange membrane according to 118 in ion separation, such as separation of

[0574] Li+from Mg2+, e.g. in an aqueous solution thereof.

[0575] 122. The ion-exchange membrane of clause 118, wherein the ion-exchange membrane is an anion- exchange membrane and wherein said side group comprises $ / \ or dl + .

[0576] 123. Use of an anion-exchange membrane according to clause 122 in a water electrolyser, a fuel cell, a CO2 electrochemical electrolyser and / or a bipolar membrane.

[0577] 124. The ion-exchange membrane of clause 118, wherein the ion-exchange membrane is a zwitterion-exchange membrane comprising the polymer according to any of clauses 75 to 117, wherein said side group comprises

[0578] 125. An electrodialysis ion-exchange membrane comprising a polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising C(=NOH)NH2 or COOH.

[0579] 126. The ion-exchange membrane of clause 118, wherein the ion-exchange membrane is an electrodialysis ion-exchange membrane, wherein

[0580] (a) each contorted aromatic moiety is as defined in any one of clauses 2 to 15 or 85 to 93 or 95 to 101 ; and / or

[0581] (b) the contorted aromatic moieties are linked by a linker moiety to form the backbone; optionally wherein the linker moiety is as defined in clauses 16 to 18 or 22 to 23.

[0582] 127. The ion-exchange membrane according to clause 125 or 126, wherein the polymer is of formula

[0583]

[0584] (Illa) (lllb) wherein CA is a contorted aromatic moiety;

[0585] Li is a linker moiety; and n is at least 2 (optionally at least 100). optionally, wherein the polymer is of formula

[0586] 128. Use of a polymer of formula as an electrodialysis ion-exchange membrane.

[0587] 129. A method of preparing a polymer (such as a polymer of intrinsic microporosity), suitably a polymer according to any of clauses 75 to 117, the method comprising polymerisation of: a monomer A comprising a contorted aromatic moiety CAi; a monomer B comprising a side group Sia or side group precursor SP; to provide an polymer comprising a polymeric backbone comprising contorted aromatic moieties and said at least one side group or side group precursor; optionally wherein the method comprises polymerisation of said monomer B comprising a side group precursor SPand wherein the method further comprises modifying the side group precursor SPof the polymeric backbone to form a side group Sia.

[0588] 130. The method according to clause 129, wherein each contorted aromatic moiety is as defined in any one of clauses 2 to 15 or 85 to 93 or 95 to 100, optionally wherein the contorted aromatic moiety is selected from one of the following:

[0589]

[0590] wherein R1-R5 are each independently selected from hydrogen, fluoride, and CF3; such as

[0591] 132. The method according to any one of clauses 129 to 131 , wherein the method further comprises polymerization of a monomer C comprising an aromatic group A1; optionally wherein A1 is a contorted aromatic moiety as defined in clause 130; and / or optionally wherein A1 is selected from one of the following:

[0592]

[0593] 133. The method according to any of clauses 129 to 132, wherein monomer B comprises a side group Sia selected from one of the following:

[0594] 134. The method of any of clauses 129 to 133, wherein polymerization is performed in the presence of an acid (optionally a sulfonic acid such as trifluoromethanesulfonic acid or methane sulfonic acid; and / or trifluoroacetic acid) and / or an organic solvent such as a chlorinated solvent, optionally wherein wherein polymerization is performed in the presence of:

[0595] (a) trifluoromethanesulfonic acid, trifluoroacetic acid, and dichloromethane; or

[0596] (b) methane sulfonic acid, and dichloromethane.

[0597] 135. The method according to any one of clauses 129 to 134, wherein the side group or side group precursor comprises the following moiety: and wherein modifying the side group precursor forms a side group selected from:

[0598] 136. The method of any of clauses 129 to 135, further comprising a second modification of amidoxime groups with an optionally substituted anhydride to form a side group comprising a carboxylic acid and an oxadiazole moiety, optionally wherein the anhydride is a cyclic anhydride, optionally comprising a ring having at least 5 ring atoms, optionally at least 6 ring atoms, optionally at least 7 ring atoms, optionally wherein the anhydride comprises one or more moieties of formula , which may be optionally substituted in the ring thereof to replace a carbon with one or more heteroatoms, such as oxygen, e.g. optionally wherein the anhydride

[0599] 137. The method according to clause 136, wherein the anhydride comprises at least one phenyl group, such as two phenyl groups or three phenyl groups, for example four phenyl groups or five phenyl groups (e.g. pendant or fused to the remainder of the anhydride).

[0600] 138. The method according to clause 136 or 137, wherein the anhydride is optionally substituted with one or more halogens, for example fluorine.

[0601] 139. The method according to any one of clauses 136 to 138, wherein the anhydride is selected from any one of the following:

[0602]

[0603] 140. The method according to any one of clauses 129 to 134, wherein the side group precursor comprises the following moiety: and wherein modifying the side group precursor forms a side group selected from:

[0604] Any listing or discussion of an apparently prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or common general knowledge. All references disclosed herein are to be considered to be incorporated herein by reference.

[0605] Those skilled in the art will recognise or be able to ascertain using no more than routine experimentation many equivalents to the specific embodiments described herein. The scope of the present embodiments described herein is not intended to be limited to the above description, but rather is as set forth in the appended claims. Those of ordinary skill in the art will appreciate that various changes and modifications to this description may be made without departing from the spirit or scope of the present disclosure, as defined in the following claims.

Claims

Claims1 . A polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprisingwherein R is an aliphatic or aromatic carboxylic acid group; wherein p is from 1 to 100; wherein wherein2. The polymer according to claim 1 , wherein the polymer is a copolymer of formula:orwherein each of CA1 and CA2are each independently a contorted aromatic moiety (which may be the same or different), or a linear aromatic moiety (which may be the same or different), wherein Sia is said side group, wherein said side group may be bonded by one bond or two bonds; wherein each of Ria, R2a and Rsa are each independently hydrogen or optionally substituted alkyl, haloalkyl, optionally substituted aryl or haloaryl (e.g. optionally wherein the aryl is bicyclic); optionally wherein each Rsa is independently a perfluorinated phenyl or 2,4-di trifluoromethyl phenyl; or wherein Ria is absent, wherein m is from 0 to 1000 (preferably from 100 to 500) and wherein n is from 0 to 1000 (preferably from 100 to 500); wherein at least one of m and n is 1 ; and wherein the sum of m and n is at least 10, optionally at least 200, optionally at least 500, such as at least 800, optionally at least 1000; wherein when said group is connected to the polymeric backbone by two bonds (optionally to form a ring), Ria is absent.

3. The polymer according to claim 1 , wherein the polymer is a copolymer of formula:wherein Ai is an aromatic group comprising at least one phenyl group, such as two or three phenyl groups; wherein CAi is a contorted aromatic moiety; wherein each of Sia and S2a are each independently said side groups (which may be the same or different); wherein said side groups may be bonded by one bond or two bonds; wherein Ria and R2a are each independently absent, hydrogen or optionally substituted alkyl, haloalkyl, optionally substituted aryl or haloaryl (e.g. optionally wherein the aryl is bicyclic); wherein m is from 1 to 1000 (preferably from 100 to 500); wherein n is from 1 to 1000 (preferably from 100 to 500); wherein the sum of m and n is at least 10, optionally at least 200, optionally at least 500, such as at least 800, optionally at least 1000; wherein when said side group bonds twice to an adjacent contorted aromatic moiety (optionally to form a ring), Ria is absent.

4. The polymer according to any preceding claim, wherein:(a) each contorted aromatic moiety comprises one of the following, which may be optionally substituted:wherein the attachment point may be any suitable substitution of H on the aromatic ring system, and optionally, as shown by the black dots; wherein each Ro is independently selected from H, OH, C1-3 alkyl (preferably CH3) or C1-3 alkoxy (preferably OCH3).(b) each contorted aromatic moiety comprises one of the following, which may be optionally substituted:wherein n is from 1 to 20. and wherein the attachment point may be any suitable substitution of hydrogen on the aromatic ring system.

5. The polymer according to any one of clauses 75 to 93; wherein the polymeric backbone further comprises an aromatic group, optionally wherein the polymeric backbone further comprises one or more of the following:wherein the attachment point may be any suitable substitution of H on the aromatic ring system.

6. The polymer according to any preceding claim, wherein:(a) the contorted aromatic moieties are linked by a linker moiety to form the backbone; and / or(b) the backbone is adapted to prevent free rotation of each contorted aromatic moiety relative to said backbone, optionally wherein the linker moiety is adapted to prevent free rotation of each contorted aromatic moiety relative to the said backbone (e.g. wherein the linker moiety bonds to at least two locations on each contorted aromatic moiety).

7. The polymer according to claim 4 wherein the linker moiety comprises an optionally substituted phenyl group or heteroaryl group, optionally wherein the linker moiety is optionally substituted:optionally, wherein the linker moiety iswherein p is from 1 to 100 or wherein the linker moiety is a single bond oralkoxy, preferably wherein the linker moiety is a single bond.

8. The polymer according to any of claims 1 to 5, wherein the polymer is of formulawherein m is from 1 to 1000 (preferably from 100 to 500); wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500); wherein p is from 1 to 100.

9. The polymer according to any preceding claim, wherein the polymer is of formulawherein n is from 1 to 1000 (preferably from 100 to 500); wherein m is from 1 to 1000 (preferably from 100 to 500); wherein x is from 1 to 1000 (preferably from 100 to 500) and wherein y is from 1 to 1000 (preferably from 100 to 500).

10. The polymer according to any preceding claim, wherein the polymer is of formulawherein n is from 1 to 1000 (preferably from 100 to 500); wherein m is from 1 to 1000 (preferably from 100 to 500); wherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500).11 . The polymer according to any preceding claim, wherein the polymer is of formulawherein x is from 1 to 1000 (preferably from 100 to 500); wherein y is from 1 to 1000 (preferably from 100 to 500).

12. A polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprisingwherein the or each side group is attached to the polymeric backbone; and wherein the polymeric backbone further comprisesmoiety pendant therefrom (optionally wherein said moiety is between adjacent contorted aromatic moieties), where R1-R5 are optionally substituted by hydrogen, fluoride, and CF3.

13. An ion-exchange membrane comprising a polymer according to any of claims 1 to 10..

14. Use of an ion-exchange membrane according claim 11 in:(a) electrodialysis; or(b) a redox flow battery; or(c) ion separation, such as separation of Li+from Mg2+, e.g. in an aqueous solution thereof.

15. An electrodialysis ion-exchange membrane comprising a polymer (such as a polymer of intrinsic microporosity) comprising a polymeric backbone comprising contorted aromatic moieties; and at least one side group comprising C(=NOH)NH2 or COOH.

16. Use of a polymer of formulaas an electrodialysis ion-exchange membrane.

17. A method of preparing a polymer (such as a polymer of intrinsic microporosity), suitably a polymer according to any of claims 1 to 10, the method comprising polymerisation of: a monomer A comprising a contorted aromatic moiety CAi; a monomer B comprising a side group Sia or side group precursor SP; to provide an polymer comprising a polymeric backbone comprising contorted aromatic moieties and said at least one side group or side group precursor; optionally wherein the method comprises polymerisation of said monomer B comprising a side group precursor SPand wherein the method further comprises modifying the side group precursor SPof the polymeric backbone to form a side group Sia.

18. The method according to claim 17, wherein monomer B comprises a side group precursor SPselected from one of the following:wherein R1-R5 are each independently selected from hydrogen, fluoride, and CF3; such as19. The method according to claim 17 or 18, wherein the side group or side group precursor comprises the following moiety:and wherein modifying the side group precursor forms a side group selected from:

20. The method according to any of claims 17 to 18, wherein the side group precursor comprises the following moiety:and wherein modifying the side group precursor forms a side group selected from:

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