A method of preparing a polymeric matrix

Abstract

There is provided a method of preparing a polymeric matrix comprising a step of polymerizing a mixture comprising a salt monomer, a crosslinker and an initiator in the presence of water and an organic solvent, wherein the salt monomer is a metal salt of an organic acid comprising at least one C=C bond, and wherein the crosslinker comprises at least 9 ethoxy groups and at least two C=C bonds. There is also provided a polymeric matrix obtained or obtainable from the method as described herein and a device comprising the polymeric matrix.

Description

[0001] A Method Of Preparing A Polymeric Matrix

[0002] References to Related Application

[0003] This application claims priority to Singapore application number 10202400304P filed with the Intellectual Property Office of Singapore on 1 February 2024, the contents of which is hereby incorporated by reference.

[0004] Technical Field

[0005] The present invention generally relates to a method of preparing a polymeric matrix. The present invention further relates to a polymeric matrix obtained or obtainable from the method as described herein and a device comprising the polymeric matrix.

[0006] Background Art

[0007] Recently, sodium ion batteries (SIB) have gained significant interest as potential candidates for the replacement of lithium ion batteries (LIB) as energy storage devices. SIB as energy storage devices afford users with many advantages such as ability to transport device at a voltage of OV, ability for device to be used at higher temperature range without the risk of thermal runaway, faster charging rates and relatively lower cost due to the greater abundances of sodium precursors.

[0008] Conventional SIBs have cations and anions that move freely across the battery. However, conventional SIBs have lower specific charge / discharge densities, shorter cycles to failure compared with LIBs. In addition, due to sodium ions being about 25% larger than lithium ions, battery volume changes would occur in conventional SIBs as ions migrate between electrodes. Further, the larger sodium ions present in the conventional SIBs would lead to sluggish ion mobility and result in a reduction in overall cell ionic conductivity. A lower overall cell ionic conductivity would lead to a reduction in sodium ion conductivity and subsequently lead to a decline in maximum current density.

[0009] Accordingly, there is a need for a battery material that ameliorates one or more disadvantages mentioned above.

[0010] Summary

[0011] In one aspect, there is provided a method of preparing a polymeric matrix, the method comprising a step of polymerizing a mixture comprising a salt monomer, a crosslinker and an initiator in the presence of water and an organic solvent, wherein the salt monomer is a metal salt of an organic acid comprising at least one C=C bond, and wherein the crosslinker comprises at least 9 ethoxy groups and at least two C=C bonds. Advantageously, the method may be performed in situ in a battery, thus additional isolation or purification steps arc not required. As the polymeric matrix may work as an electrolyte, the method may be used to prepare a battery electrolyte efficiently in a single-step manner.

[0012] Further advantageously, the polymeric matrix is polymerized from the salt monomer, thus it comprises salt moictics but docs not require an additional step to form the salt moictics (c.g., via neutralization of acid moictics with an excess amount of base). In conventional batteries, where an excess amount of base is used, some base (such as hydroxides) may be trapped in the polymeric matrix and become attached to metal cations. Therefore, the present polymeric matrix may be made in situ in a battery without concerns of residual hydroxides while conventional batteries require additional works to remove the residual hydroxides. The presence of hydroxides is detrimental to performances of the battery as it corrodes electrodes in the battery and there is no feasible means to remove hydroxides while keeping metal cations in the battery, which arc a crucial and integral part of the battery, thus the present method is advantageous over conventional methods by using the salt monomer.

[0013] Still further advantageously, the organic solvent used in the method may form intcrmolccular hydrogen bonds with water. Therefore, when the polymeric matrix is made into a battery, the organic solvent would prevent water molecules from attacking electrodes and producing undesirable by-products that would lead to degradation of the battery. The battery would have a small electrochemical stability window of about 1.23 V in the absence of the organic solvent. Where the organic acid is present, the electrochemical stability window would be increased to about 3 to 4 V. In addition, the organic solvent may also serve as a solvating agent for the salt monomer and prevent reduction of water molecules at anode in the battery.

[0014] Still further advantageously, the salt monomer comprises at least one C~C bond. The C=C bond may be polymerized to form an alkyl chain in a very efficient manner (c.g., via UV treatment) compared with other polymerizable moictics. For example, polymerization of amine / carboxylic acid moictics generally requires heating which is not possible to form aqueous electrolytes due to the presence of water. Polymerization of isocyanate / alcohol (to form polyurethane) is also incompatible with water due to side reactions between isocyanate with water to form carbamic acid groups and carbon dioxide. Polymerization of amine / epoxy moictics is generally undertaken at room temperature and requires a long duration of a few hours.

[0015] Still further advantageously, the crosslinker comprises at least 9 ethoxy groups, which stabilizes the polymeric matrix. Where the crosslinkcr comprises less than 9 ethoxy groups, the mixture would turn cloudy before the polymerizing step. A minimum of 9 ethoxy groups is required to create a minimum free volume within the polymeric matrix that arc inter-connected to achieve necessary percolation chnncls for ion movement while preventing agglomeration of the polymeric matrix. Still further advantageously, the polymeric matrix docs not comprise chloride or fluoride ions, thus degradation products of the polymeric matrix arc relatively less toxic.

[0016] In another aspect, there is provided a polymeric matrix obtained or obtainable from the method as described herein.

[0017] Advantageously, the polymeric matrix comprises metal ions that are permanently immobilized onto it. The metal ions may improve conductivity and transference capability of the polymeric matrix.

[0018] Further advantageously, the polymeric matrix comprises at least 9 ethoxy groups. The ethoxy groups may serve as an emulsifier that promotes mixing between the metal ions and the polymeric matrix.

[0019] In another aspect, there is provided a device comprising the polymeric matrix as described herein.

[0020] Advantageously, during charging or discharging of the device, only sodium ions are mobile, resulting in a significant improvement in ionic conductivity compared with conventional devices with free anions.

[0021] Definitions

[0022] The following words and terms used herein shall have the meaning indicated:

[0023] The word “substantially” does not exclude “completely” e.g. a composition which is “substantially free” from Y may be completely free from Y. Where necessary, the word “substantially” may be omitted from the definition of the invention.

[0024] Unless specified otherwise, the terms "comprising" and "comprise", and grammatical variants thereof, are intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, unrecited elements.

[0025] The term "about" as used herein typically means + / - 5 % of the stated value, more typically + / - 4 % of the stated value, more typically + / - 3 % of the stated value, more typically, + / - 2 % of the stated value, even more typically + / - 1 % of the stated value, and even more typically + / - 0.5 % of the stated value.

[0026] Throughout this disclosure, certain embodiments may be disclosed in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the disclosed ranges. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

[0027] Certain embodiments may also be described broadly and generically herein. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the disclosure. This includes the generic description of the embodiments with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein.

[0028] Detailed Disclosure of Embodiments

[0029] Exemplary, non-limiting embodiments of a method of preparing a polymeric matrix will now be disclosed.

[0030] The method comprises the step of polymerizing a mixture comprising a salt monomer, a crosslinker and an initiator in the presence of water and an organic solvent, wherein the salt monomer is a metal salt of an organic acid comprising at least one C=C bond, and wherein the crosslinker comprises at least 9 ethoxy groups and at least two C=C bonds.

[0031] The method may not comprise additional isolation or purification steps.

[0032] Therefore, the method may consist of or consist essentially of the step of polymerizing a mixture comprising a salt monomer, a crosslinker and an initiator in the presence of water and an organic solvent.

[0033] In the method, the salt monomer may be a lithium salt, a sodium salt, a potassium salt, a magnesium salt, a zinc salt, or a combination thereof. The salt monomer may be a sodium salt.

[0034] The organic acid may be a carboxylic acid, a sulfonic acid, an acrylic acid, a methacrylic acid or a combination thereof.

[0035] The C=C bond in the salt monomer may be polymerized to form alkyl chains. As a C=C bond is present in an acrylic acid and a methacrylic acid, the salt monomer does not require a separate C=C bond if the organic acid is acrylic acid or methacrylic acid.

[0036] The salt monomer may be selected from the group consisting of sodium 3- [(trifluoromethane)sulfonamidosulfonyl]propyl methacrylate, sodium methacrylate (SMA), sodium acrylate, 2- acrylamido-2-methyl- 1 -propanesulfonic acid sodium salt, sodium 2-methyl-2-propene-l -sulfonate, lithium 3-

[0037] [(trifluoromethane)sulfonamidosulfonyl]propyl methacrylate, lithium methacrylate (LMA), lithium acrylate, 3-sulfopropyl methacrylate potassium salt or combinations thereof.

[0038] The crosslinker may crosslink the alkyl chains formed from the salt monomer.

[0039] As the crosslinkcr comprises at least 9 ethoxy groups, the crosslinkcr may be regarded as a derivative of polyethylene glycol (PEG) or polyethylene oxide (PEG).

[0040] The number of ethoxy groups is not particularly limited as long as the crosslinker is a liquid at room temperature.

[0041] The number of ethoxy groups may be in the range of about 9 to about 30, about 9 to about 20, about 9 to about 15, about 15 to about 20 or about 15 to about 30.

[0042] The crosslinker may be selected from the group consisting of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, trimethylolpropane ethoxylate triacrylate, trimethylolpropane ethoxylate trimethacrylate, bisphenol A polyethylene glycol diether dimethacrylate, polyethylene glycol monomethyl ether methacrylate or combinations thereof.

[0043] As a C=C bond is present in an acrylic acid and a methacrylic acid, the crosslinker may comprise two acrylic moieties, methacrylic moieties, or a combination thereof.

[0044] The crosslinker and the salt monomer may have a molar ratio in the range of about 0.03:1 to about 8: 1, about 1:1 to about 8: 1 or about 0.03: 1 to about 1: 1. Where the molar ratio between the crosslinker and the salt monomer is high (e.g., above 1:1, above 2: 1 or about 3:1), the polymeric matrix may have a high ion conductivity of at least 3 x 10'4S ■ cm1, at least 4 x 10"4S • cm'1or at least 5 x 10'4S ■ cm1.

[0045] The initiator may be a photoinitiator or a thermal initiator. The initiator may be a Type 1 photoinitiator or a Type 11 photoinitiator.

[0046] The initiator may be selected from the group consisting of methyl benzoylformate, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone (HMPP), azobisisobutyronitrile and combinations thereof.

[0047] The initiator may have a weight percentage in the range of about 0.1 weight% to about 20 weight%, about 1 weight% to about 20 weight%, about 10 weight% to about 20 weight%, about 0.1 weight% to about 10 weight% or about 0.1 weight% to about 1 weight%, based on the total weight of the combination of the salt monomer and the crosslinker.

[0048] The organic solvent may be a non-volatile liquid. Therefore, the organic solvent is ideal for battery electrolyte applications as it is not easily lost due to evaporation. The organic solvent may have a boiling point of at least about 100 °C, about 150 °C or about 200 °C. The organic solvent may be miscible with water at room temperature to form a homogeneous mixture that docs not phase separate when made to stand still for at least about 1 hour, about 2 hours or about 3 hours.

[0049] The organic solvent may have a dipole moment of at least about 2.0 D, about 2.5 D or about 3.0 D.

[0050] The organic solvent may be non-flammable.

[0051] The organic solvent may be a carbonate, a sulfite, a phosphite, a sulfone or a combination thereof.

[0052] The organic solvent may be selected from the group consisting of fluoroethylene carbonate, propylene carbonate, ethylene carbonate (EC), dimethyl carbonate, diethyl carbonate, ethylene sulfite, 1,3-propylene sulfite, ethylene phosphite, sulfolane, polyethylene glycol dimethyl ether (PEGDME, with an Mnof about 250) and combinations thereof.

[0053] Water and the organic solvent may have a molar ratio in the range of about 0.2:1 to about 10: 1, about 1:1 to about 10:1 or about 0.2: 1 to about 1:1.

[0054] The mixture may further comprise additives.

[0055] The additives may be polythiols, nano-ceramic fillers or a combination thereof.

[0056] Advantageously, the polythiols may promote a more complete reaction by consuming all C=C bonds in the mixture with thiol moieties.

[0057] Advantageously, the nano-ceramic fillers may strengthen the polymeric matrix.

[0058] The additives may be selected from the group consisting of dipentaerythritol hexakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropi onate), pendant acrylate / methacrylate (e.g., tetrahydrofurfuryl methacrylate) and combinations thereof.

[0059] Where polythiols are present as addtives, the polythiols may have a weight percentage in the range of about 0.1 weight% to about 3 weight%, about 1 weight% to about 3 weight% or about 0.1 weight% to about 1 weight%, based on the total weight of the mixture.

[0060] Tn the mixture, water and the organic solvent may have a combined volume percentage in the range of about 30 volume% to about 65 volume%, about 50 volume% to about 65 volume%, about 30 volume% to about 50 volume%, about 40 volume% to about 50 volume%, about 40 volume% to about 45 volume%, about 45 volume% to about 50 volume%, about 50 volume% to about 60 volume% or about 50 volume% to about 55 volume%, based on the total volume of the mixture. A higher combined volume percentage of water and the organic solvent leads to higher ion conductivity. However, where the combined volume percentage of water and the organic solvent is too high, the polymeric matrix may have a liquid phase that is more likely to leak out over time and the polymeric matrix would have a poor mechanical strength. The combined volume percentage of water and the organic solvent of the present polymeric matrix advantageously balances the ion conductivity and the mechanical strength of the polymeric matrix.

[0061] The mixture may comprise sodium methacrylate, polyethylene glycol dimcthacrylatc (with about 14 repeating units of ethylene glycol) and 2-hydroxy-2- mcthylpropiophcnonc, wherein sodium methacrylate and polyethylene glycol dimcthacrylatc have a molar ratio in the range of about 2 to about 3; and sodium methacrylate and 2-hydroxy-2-methylpropiophenone have a molar ratio in the range of about 3 to about 4.

[0062] Where the initiator is a photoinitiator, the polymerizing step may be undertaken in the presence of light.

[0063] The light may be UV radiation having an intensity in the range of about 100 mW / cm2to about 200 mW / cm2, about 100 mW / cm2to about 150 mW / cm2or about 150 mW / cm2to about 200 mW / cm2. The light may be UV radiation having an intensity of about 125 mW / cm2.

[0064] Where the initiator is the photoinitiator, the polymerizing step may be undertaken at room temperature.

[0065] Where the initiator is the photoinitiator, the polymerizing step may be undertaken for a duration in the range of about 5 minutes to about 20 minutes, about 5 minutes to about 10 minutes or about 10 minutes to about 20 minutes. The polymerizing step may be undertaken for a duration of about 10 minutes.

[0066] Where the initiator is a thermal initiator, the polymerizing step may be undertaken at a temperature in the range of about 50 °C to about 100 °C, about 70 °C to about 100 °C or about 50 °C to about 70 °C. The polymerizing step may be undertaken at a temperature of about 70 °C.

[0067] Where the initiator is the thermal initiator, the polymerizing step may be undertaken for a duration in the range of about 0.5 hour to about 2 hours, about 1 hour to about 2 hours or about 0.5 hour to about 1 hour. The polymerizing step may be undertaken for a duration of about 1 hour.

[0068] Where the initiator is the thermal initiator, the polymerizing step may be undertaken in a sealed system, such as a vacuum bag.

[0069] Exemplary, non-limiting embodiments of a polymeric matrix will now be disclosed. The polymeric matrix is obtained or obtainable from the method as described herein.

[0070] The polymeric matrix may comprise a polymer having the following structure:

[0071] Exemplary, non-limiting embodiments of a device will now be disclosed.

[0072] The device comprises the polymeric matrix as described herein.

[0073] The device may be an electrochemical device.

[0074] The device may be a battery.

[0075] The device may be a free standing / solid state battery. Therefore, the device docs not require a structural casing as support.

[0076] Brief Description of Drawings

[0077] The accompanying drawings illustrate a disclosed embodiment and serves to explain the principles of the disclosed embodiment. It is to be understood, however, that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention.

[0078] FIG. 1

[0079] [FIG. 1] shows an illustration of an embodiment of the polymeric matrix as described herein.

[0080] FIG. 2A

[0081] [FIG. 2A] shows an illustration of solvation of a sodium cation in the polymeric matrix as described herein. FIG. 2B

[0082] [FIG. 2BJ shows an illustration of water molecule anchoring by polar solvent in the polymeric matrix as described herein.

[0083] FIG. 3

[0084] [FIG. 3] shows a representative synthetic scheme of an embodiment of the polymeric matrix as described herein.

[0085] FIG. 4

[0086] [FIG. 4J shows infrared spectra of several embodiments of the polymeric matrix as described herein in comparison with comparative examples.

[0087] Examples

[0088] Non-limiting examples of the invention will be further described in greater detail by reference to specific Examples, which should not be construed as in any way limiting the scope of the invention.

[0089] Example 1 - Preparation of A Polymeric Matrix

[0090] An exemplary structure of the polymeric matrix according to the present disclosure is provided in FIG. 1. In the exemplary structure, there may be solvation of sodium cations and anchoring of watering molecules by polar solvents as shown in FIGs. 2A and 2B. The exemplary structure was prepared by mechanically blending weighed components in a one-pot system and cured. A representative synthetic scheme is shown in FIG. 3.

[0091] Generally, a mixture of an organic solvent and water was prepared in a separate bottle with a mass ratio of about 4:6. Subsequently, a salt monomer, a crosslinker and an initiator were added to the mixture, where the initiator had a weight percentage of about 10 wcight% based on the total weight of the solid components. The mixture was blended mechanically until the salt monomer was fully dissolved and the mixture was fully homogeneous. The mixture was subsequently cast into a silicone mold, followed by curing via UV initiation using a UV radiation source which was more than 30 mM for about 10 minutes under an inert atmosphere where a photoinitiator was used. The reagents tested are listed below.

[0092] A list of the representative compounds used is provided below:

[0093] Salt monomer - Sodium methacrylate (SMA, purchased from Tokyo Chemical Industry, Tokyo, Japan).

[0094] Salt (comparative) - Sodium triflatc (NaTRF, purchased from Tokyo Chemical Industry, Tokyo, Japan) and sodium trifluoroacctatc (NaTFA, purchased from Tokyo Chemical Industry, Tokyo, Japan). Crosslinkcr - Polyethylene glycol dimcthacrylatc (PEGDMA, n = 14, purchased from Tokyo Chemical Industry, Tokyo, Japan).

[0095] Initiator - 2-hydroxy-2-methylpropiophenone (HMPP, purchased from Sigma Aldrich, Singapore).

[0096] Organic solvent - Ethylene carbonate (EC, purchased from Sigma Aldrich, Singapore).

[0097] Water - Deionised water (purchased from millipore filtered water, Singapore).

[0098] To investigate the impact of the chemical composition on the ion conductivities (1C) and electrochemical stability window (ECV) of the polymeric matrix formed, various examples and comparative examples were prepared as listed in Table 1.

[0099] Table 1. Formulation used to prepare a polymeric matrix

[0100] To determine the impact of the molar ratio between the crosslinker and the sodium ion on the present polymeric matrix, sample Al was prepared with a higher crosslinker-to-sodium ratio as compared with samples DI and D2, but with the same concentration of sodium ion. To determine the impact of the concentration of sodium ion, sample D3 was prepared with a higher concentration of sodium ion as compared with sample DI, but with the same crosslinker-to-sodium ratio. To determine the impact of counterion mobility within the polymeric matrix on the properties of the polymeric matrix, comparative samples Cl and Fl were prepared with sodium salts that did not have reactive coupling sites (NaTRF and NaTFA) as a basis for comparison with sample D2.

[0101] Example 2 - Infrared Analysis of Polymeric Matrix

[0102] The samples prepared as listed in Example 1 were characterized using FTIR-ATR spectroscopy to explore bonds formed within the polymeric matrix. The characterization was performed with a detector in contact with the far side of the samples (c.g., further away from UV source), so as to determine the completeness of the UV-drivcn photo-polymerization. FIG. 4 reveals the FTIR spectrums of samples DI, D2, D3 and Al, measured in the range of 400 to 4000 cm'1. Commercially purchased PEGDMA (n = 14) and SMA precursors were subjected to FTIR analysis without further purification procedures. The measurements were performed to serve as baseline for comparisons with the representative samples of the present polymeric matrix to determine the difference in bonds within each specimen.

[0103] It could be observed in FIG. 4 that pure PEGDMA (n = 14) possessed a medium absorbance peak at 1641 cm1. This peak was attributed to C'-C bond stretching of the two methacrylate terminals located at the end of the PEGDMA chains. This peak was absent in the FTIR spectra of samples DI, D2, D3 and Al. Thus, it was concluded that most, if not all, of the methacrylate anions of SMA have been successfully bonded to the polymeric matrix via the double bond sites of PEGDMA (n = 14).

[0104] Example 3 - Ionic Conductivities and Storage Moduli of Polymeric Matrix

[0105] Table 2. Ionic conductivities and storage modulus of polymeric matrices prepared

[0106] The ionic conductivities and storage moduli of the polymeric matrices prepared arc listed in Table 2 above. By comparing samples Al and DI, it could be observed that the ionic conductivity of DI was significantly higher than that of Al. This could be attributed to sample Al containing 35 volumc% (as percentage of total volume of the polymeric matrix) of liquid electrolyte as compared with 46 volumc% in DI despite having the same concentration of sodium ion of 2.558 M. Thus, more percolation channels were established within the polymeric matrix of DI, resulting in a higher ionic conductivity. The lower loading of PEGDMA (n = 14) within sample DI also implied that the crosslinking density of the polymeric matrix was lower, thus leading to an increase in free volume within the gel and more percolation channels formed, causing a higher ionic conductivity recorded. Samples C 1 and Fl were prepared using sodium salts NaTRF and NaTFA, respectively, with the remaining formulation basis being the same as DI. It could be observed that both samples possessed lower ionic conductivities and storage moduli as compared to DI. This demonstrated that sample DI, with methacrylate anion immobilized via physical bonding to the polymeric matrix through polymerization, resulted in a polymeric matrix with higher ionic conductivity as only the sodium ions moved under an applied voltage. This feature of a non-mobilc anion was not present in the polymeric matrices of samples Cl and Fl, thus lowering the measured ionic conductivities. The storage moduli of both Cl and Fl were lower than that of DI, which demonstrated that the crosslinking of methacrylate anion to the polymeric matrix had a positive strengthening impact on the polymeric matrix.

[0107] By comparing samples D2 and D3, it could be observed that a higher concentration of sodium salt in D3 resulted in poorer ionic conductivity as compared to D2. This could be accounted for due to sample D2 containing 54 volumc% of liquid electrolyte as compared to 40 volumc% in D3, thus more percolation channels were established in the polymeric matrix of D2 as compared to D3, resulting in higher ionic conductivity for sample D2. Likewise, D2 had the lowest measured storage modulus due to the highest volume percentage of electrolyte within the polymeric matrix. The significantly higher recorded ionic conductivity for sample D2 as compared to the rest of the samples, despite having the same concentration of sodium salt of 2.558 M, could be due to the lower crosslinkcr-to-sodium ratio. The lower loading of crosslinkcr PEGDMA (n = 14) within the sample D2 resulted in lower crosslinking density within the polymeric matrix, thus allowing more free volume to form more connected percolation channels, resulting in higher recorded ionic conductivity.

[0108] It could also be observed that D5 possessed a slightly higher onset temperature as compared to D2. Sample D5 was prepared with a significantly higher loading of AMF as compared to D2. AMF as an ionic liquid had innate higher thermal degradation temperature, which led to more energy required to degrade the polymeric network. The higher requirement of energy led to an increase in degradation temperature for D5.

[0109] Industrial Applicability

[0110] The polymeric matrix of the disclosure may be used in a variety of electro-chemical devices. The polymeric matrix of the disclosure may be used in applications such as electric vehicles, personal mobility devices, mobile phones, maritime, rail systems, micro-batteries, wearables or ion exchange membranes.

[0111] It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.

Claims

Claims1. A method of preparing a polymeric matrix, the method comprising a step of polymerizing a mixture comprising a salt monomer, a crosslinker and an initiator in the presence of water and an organic solvent, wherein the salt monomer is a metal salt of an organic acid comprising at least one C=C bond, and wherein the crosslinker comprises at least 9 ethoxy groups and at least two C=C bonds.

2. The method of claim 1, wherein the method consists of the step of polymerizing a mixture comprising a salt monomer, a crosslinkcr and an initiator in the presence of water and an organic solvent.

3. The method of claim 1 or 2, wherein the salt monomer is selected from the group consisting of a lithium salt, a sodium salt, a potassium salt, a magnesium salt, a zinc salt, and combinations thereof.

4. The method of any one of claims 1 to 3, wherein the organic acid is selected from the group consisting of a carboxylic acid, a sulfonic acid, an acrylic acid, a methacrylic acid, and combinations thereof.

5. The method of any one of claims 1 to 4, wherein the crosslinker is selected from the group consisting of polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, trimethylolpropane ethoxylate triacrylate, trimethylolpropane ethoxylate trimethacrylate, bisphenol A polyethylene glycol diether dimethacrylate, polyethylene glycol monomethyl ether methacrylate, and combinations thereof.

6. The method of any one of claims 1 to 5, wherein the initiator is selected from the group consisting of methyl benzoylformate, 2,2-dimcthoxy-2-phcnylacctophcnonc, 2- hydroxy-2-mcthylpropiophcnonc (HMPP), azobisisobutyronitrile, and combinations thereof.

7. The method of any one of claims 1 to 6, wherein the organic solvent is selected from the group consisting of fluoroethylene carbonate, propylene carbonate, ethylene carbonate (EC), dimethyl carbonate, diethyl carbonate, ethylene sulfite, 1,3-propylene sulfite, ethylene phosphite, sulfolane, polyethylene glycol dimethyl ether (PEGDME) and combinations thereof.

8. The method of any one of claims 1 to 7, wherein the crosslinker and the salt monomer have a molar ratio in the range of about 0.03: 1 to about 8:1.

9. The method of any one of claims 1 to 8, wherein the initiator has a weight percentage in the range of about 0.1 weight% to about 20 weight%, based on the total weight of the combination of the salt monomer and the crosslinker.

10. The method of any one of claims 1 to 9, wherein water and the organic solvent have a molar ratio in the range of about 0.2:1 to about 10:1.

11. The method of any one of claims 1 to 10, wherein the mixture further comprises an additive.

12. The method of any one of claims 1 to 11, wherein water and the organic solvent have a combined volume percentage in the range of about 30 volume% to about 65 volume% based on the total volume of the mixture.

13. The method of any one of claims 1 to 12, wherein: the mixture comprises sodium methacrylate, polyethylene glycol dimethacrylate and 2-hydroxy-2-methylpropiophenone; sodium methacrylate and polyethylene glycol dimethacrylate have a molar ratio in the range of about 2 to about 3 ; and sodium methacrylate and 2-hydroxy-2-methylpropiophenone have a molar ratio in the range of about 3 to about 4.

14. The method of any one of claims 1 to 13, wherein the initiator is a photoinitiator.

15. The method of claim 14, wherein the polymerizing step is undertaken in the presence of UV radiation having an intensity in the range of about 100 mW / cm2to about 200 mW / cm2.

16. The method of any one of claims 1 to 13, wherein the initiator is a thermal initiator.

17. The method of claim 16, wherein the polymerizing step is undertaken at a temperature in the range of about 50 °C to about 100 °C.

18. A polymeric matrix obtained or obtainable from the method of any one of claims 1 to 17.

19. The polymeric matrix of claim 18, wherein the polymeric matrix comprises a polymer having the following structure:

20. A device comprising the polymeric matrix of claim 18 or 19.

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