A composite material

Abstract

There is provided a composite material comprising a metal-organic framework (MOF) connected to a dynamic covalent polymer (DCP) via a permanent covalent bond. There is also provided a method of preparing a composite material and an article comprising the composite material.

Description

[0001] A Composite Material

[0002] References to Related Application

[0003] This application claims priority to Singapore application number 10202500374P filed with the Intellectual Property Office of Singapore on 10 February 2025, the contents of which is hereby incorporated by reference.

[0004] Technical Field

[0005] The present invention generally relates to a composite material. The present invention further relates to method of preparing a composite material and an article comprising the composite material.

[0006] Background Art

[0007] Metal-organic frameworks (MOFs) are 3D porous networks formed by coordination bonds between metal-containing nodes and organic ligands. Due to the customisable chemistry of MOFs, tunable selective adsorption of guest molecules can be achieved. Thus, MOFs can be used in applications such as catalysis, separation, filtration and purification.

[0008] As MOFs are crystalline, membranes made with only MOF tend to be brittle and easily damaged. Hence, conventionally, MOFs are incorporated into mixed matrix membranes (MMMs) with polymers to form self-supported membranes. Most conventional membranes are simple blends of MOFs with the polymer (see FIG. 1A, where the polymer 102 is blended with the MOF 104), some with added covalent bonds between the MOF and polymer chain (see FIG. 1B, where the MOF 106 is functionalised to form covalent linkages with the polymer 102). However, these MMMs have several drawbacks such as poor compatibility between MOF and polymer matrix, and poor homogeneity and reproducibility as a result. Additionally, damages to the MMM cannot be easily repaired.

[0009] Dynamic covalent polymers (DCPs) are a class of polymer networks bearing dynamic covalent bonds. These bonds endow DCPs with stimuli -responsive properties such as self-healing and reprocessability. Accordingly, another conventional membrane comprises MOFs incorporated into DCPs by simple mixing (see FIG. 1C, where the polymer 102 comprising the dynamic covalent bonds 108 is mixed with the MOF 104) to achieve a self-healing MMM. In yet another conventional membrane, MOFs are connected with DCP via dynamic covalent bonds (see FIG. ID, where the MOF 106 is functionalised to form dynamic covalent bonds 110 with the polymer, which comprises additional dynamic covalent bonds 108 within itself). However, these conventional membranes have drawbacks such as undesirable changes in performance after recycling. The MOF -DCP composites exhibit changes in material properties due to the inherent different reactivities of the dynamic covalent bondswithin the DCP and between the DCP and MOF. Accordingly, there is a need for a composite material that ameliorates one or more disadvantages mentioned above.

[0010] Summary

[0011] In one aspect, there is provided a composite material comprising a metal-organic framework (MOF) connected to a dynamic covalent polymer (DCP) via a permanent covalent bond.

[0012] Advantageously, the composite material is reprocessable, recyclable and self-healing due to the presence of the dynamic covalent polymer.

[0013] Further advantageously, the present composite material may be recycled via mechanical recycling by application of elevated temperature and pressure, or via chemical recycling to cleave the DCP due to the presence of the dynamic covalent bonds within the DCP.

[0014] Still further advantageously, the composite material has a high inherent structural rigidity due to the presence of the MOF. The structural rigidity of the MOF allows the composite material to stabilize defects (e.g., due to missing organic ligands), thereby increasing a total number of catalytic and absorptive sites that can be present on the metal-containing nodes. In contrast, conventional composite materials derived from small-molecule substances (such as metal-organic polyhedra or MOP) lack the crucial structural rigidity. Therefore, the conventional composite materials are prone to collapsing when defects are introduced, resulting in a reduced functionality compared to the present composite material. Thus, the present composite material may be used in more applications compared to conventional composite materials (e.g., those made from MOP).

[0015] Still further advantageously, the MOF and the DCP are coupled via permanent covalent bonds. Hence, the composite material requires the presence of both dynamic covalent bonds (within the DCP) and permanent covalent bonds (between the MOF and DCP). This makes the present composite material more stable than conventional composite materials which use non-covalent bonds (e.g., van der Waals’ interaction and / or electrostatic interaction) or non-permanent covalent bonds (e.g., dynamic covalent bonds). Due to the coupling via permanent covalent bonds, the present composite material may have no degradation or substantially no degradation for at least 10 days at a pH value of at least 10.

[0016] Still further advantageously, the composite material may have more stable properties upon reprocessing or recycling compared to composite materials that have dynamic covalent bonds between the MOF and the DCP. This is because the permanent covalent bond between the MOF and the DCP cannot be altered during reprocessing or recycling.In another aspect, there is provided a method of preparing a composite material, comprising the step of reacting a MOF with a DCP at an elevated temperature to form one or more permanent covalent bonds between the MOF and the DCP.

[0017] Advantageously, as the MOF and the DCP are prepared separately from the reacting step, the present method may provide a better control of the number of permanent covalent bonds formed compared to methods where the MOF, the DCP and the permanent covalent bond are formed together (e.g., in one pot). Therefore, the present method may be considered highly scalable and reproducible.

[0018] In another aspect, there is provided an article comprising the composite material as described herein.

[0019] Advantageously, the article may have high catalytic and absorptive / adsorptive activities due to the presence of the MOF.

[0020] Further advantageously, the article may have a high flexibility and reprocessability due to the presence of dynamic covalent bonds in the composite material.

[0021] Definitions

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

[0023] As used herein, the terms “metal-organic framework” and “MOF” refer to a three-dimensional polymeric network comprising a plurality of metal-containing nodes and organic ligands that are linked by coordination bonds. The metal-organic framework is crystalline in nature, thus the metal-organic framework is insoluble in common solvents e g., neutral (at a pH value of about 7) water and organic solvents.

[0024] As used herein, the term “dynamic covalent bond” refers to a covalent bond that can be reversibly cleaved and reformed autonomously at a temperature less than or equal to 250 °C.

[0025] As used herein, the term “dynamic covalent polymer” and “DCP” refer to a polymer that is at least partially made up of dynamic covalent bonds. Therefore, the DCP may form an eventual composite network that is cross-linked and yet malleable and / or recyclable at elevated temperatures.

[0026] As used herein, the term “permanent covalent bond” refers to a covalent bond that is stable (i.e., not cleaved or not substantially cleaved) at up to 250 °C.

[0027] 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.

[0028] Unless specified otherwise, the terms "comprising" and "comprise", and grammatical variants thereof, are intended to represent "open" or "inclusive" language such thatthey include recited elements but also permit inclusion of additional, unrecited elements.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] Detailed Disclosure of Embodiments

[0033] Exemplary, non-limiting embodiments of a composite material will now be disclosed.

[0034] The composite material comprises a MOF connected to a DCP via a permanent covalent bond.

[0035] The MOF comprises a plurality of metal-containing nodes and a plurality of organic ligands. Therefore, each MOF may be coupled to one or more DCPs via permanent covalent bonds. Accordingly, the MOF may be considered as cross-linking the DCPs via permanent covalent bonds.

[0036] The DCP may be linear, branched or cross-linked so long as the DCP has excess reactive sites which can react with the MOF to form permanent covalent bonds, and the MOF can be well-mixed with the DCP.

[0037] Where the DCP is linear, the DCP may be derived from monomers that have two reactive ends. As three or more reactive ends are required in a monomer to cross-link a polymer or form branching structures, the linear DCP may not comprise any crosslinkers and may not cross-link by itself. As the DCP is covalent in nature, it may beregarded as an organic polymer. Therefore, when the DCP is linear, the composite material may not comprise any organic cross-linkers.

[0038] Where the DCP is branched or cross-linked, the DCP may be derived additionally from monomers that have at least three reactive ends.

[0039] Advantageously, where the DCP is not cross-linked, the present composite material may have an improved permeability compared to materials comprising branching or cross-linked DCP. Guest species / substrates will need to enter pores of MOF to function, thus limited permeability due to the presence of cross-linkers could reduce efficacies of absorption, adsorption, catalysis, and other functions of the present composite material.

[0040] The DCP may comprise hydrophilic segments, hydrophobic segments or a combination of both. Where the DCP comprises both hydrophilic segments and hydrophobic segments, the composite material may show a thermo-responsive behavior when dissolved.

[0041] The plurality of metal-containing nodes in the MOF may be derived from a multivalent metal ion to allow for the formation of the three-dimensional polymeric network. The multivalent metal ion may be a metal ion to allow for the formation of the coordination bonds. The metal ion may be a main group metal ion (i.e., of a metal of any one of Groups 1, 2 and 13 to 17 in the Periodic Table of Elements), a transition metal ion (i.e., of a metal of any one of Groups 3 to 12 in the Periodic Table of Elements) or a lanthanide metal ion (i.e., of a metal having an atomic number in the range from 57 to 70). The metal ion may be formed from a metal selected from the group consisting of zirconium, zinc, nickel, manganese, copper, chromium, cadmium, iron, aluminum and combinations thereof.

[0042] The plurality of organic ligands in the MOF may form coordination bonds with the plurality of metal-containing nodes. The plurality of organic ligands may couple two or more metal-containing nodes and couple the MOF to the DCP. Therefore, each of the plurality of organic ligands may comprise two or more reactive sites such as amino moieties or carboxylic acid moieties. Each of the plurality of organic ligands may independently have two or more moieties selected from amino moieties, carboxylic acid moieties or a derivative (e.g., acyl chloride or anhydride) thereof, epoxides or a combination thereof. The plurality of organic ligands may be selected from terephthalic acid optionally functionalised with an amino, a hydroxyl or mercapto group (e.g., 2-aminoterephthalic acid, hydroxyterephthalic acid or mercaptoterephthalic acid), trimellitic acid, trimesic acid, functionalised bipyridine (e.g., 3-amino-4,4’-bipyridine), functionalised imidazole (e.g., 2-aminoimidazole or 3-amino-l,2,4-triazole) or a combination thereof.

[0043] The plurality of organic ligands in the MOF may be derived from post-synthetic modifications.The plurality of organic ligands in the MOF may comprise one or more acyl chloride moieties that are derived from post-synthetic modifications of carboxylic acid moi eties (e.g., from trimellitic acid) via reactions with a thionyl chloride.

[0044] The plurality of organic ligands in the MOF may comprise one or more anhydride moieties that are derived from post-synthetic modifications of carboxylic acid moieties (e.g., from trimellitic acid) via reactions with an acid chloride.

[0045] The plurality of organic ligands in the MOF may comprise one or more epoxide moieties that are derived from post- synthetic modifications of hydroxyl moieties (e.g., from hydroxylterephthalic acid) via reactions with epichlorohydrin.

[0046] The dynamic covalent bonds within the DCP may be selected according to reactive sites present on the organic ligands (which would determine applications and selectivities of the MOF). The dynamic covalent bonds within the DCP may be selected from the group consisting of:

[0047] o o o '' N \.s- K. J - s TT HN' HN "?n

[0048] X

[0049]

[0050] H, >, 5, ", and combinations thereof. The dynamic covalent bonds within the DCP may be selected from imine bonds, urea bonds or P-hydroxy ester bonds.

[0051] The permanent covalent bond connecting the MOF and the DCP may be a C-N bond such as an amine bond or an amide bond.

[0052] Where the DCP comprises terminal epoxide groups, the organic ligands in the MOF may comprise amine groups to form amine bonds with the terminal epoxide groups. Where the DCP comprises terminal carboxylic acid / anhydride groups, the organic ligands in the MOF may comprise amine groups to form amide bonds with the terminal carboxylic acid / anhydride groups.

[0053] Where the DCP comprises terminal amine groups, the organic ligands in the MOF may comprise:

[0054] 1) epoxide groups to react with the terminal amine groups to form amine bonds; and / or2) acyl chloride groups to react with the terminal amine groups to form amide bonds. For example, where the DCP comprises one or more p-hydroxy ester bonds formed by epoxide groups and carboxylic / anhydride groups, the DCP may comprise residual epoxide groups and / or carboxylic / anhydride groups. Therefore, the organic ligands in the MOF may comprise amine moi eties to react with:

[0055] 1) the residual epoxide groups in the DCP to form amine bonds; and / or

[0056] 2) the residual carboxylic acid / anhydride groups in the DCP to form amide bonds. In another example, where the DCP comprises one or more imine bonds formed by aldehyde groups and amine groups, the DCP may comprise residual amine groups. Therefore, the organic ligands in the MOF may comprise:

[0057] 1) epoxide groups to react with the residual amine groups to form amine bonds; and / or

[0058] 2) acyl chloride groups to react with the residual amine groups to form amide bonds. In another example, where the DCP comprises one or more urea bonds formed by amine groups and isocyanate groups, the DCP may comprise residual amine groups. Therefore, the organic ligands in the MOF may comprise:

[0059] 1) epoxide groups to react with the residual amine groups to form amine bonds; and / or

[0060] 2) acyl chloride groups to react with the residual amine groups to form amide bonds. The DCP may be derived from, polymerized from or obtained from monomers (herein termed “DCP monomers”) that comprise moieties selected from the group consisting of carboxylic acid, hydroxyl, carbonyl, amino, sulfide, sulfhydryl, amide, C=C double bond, epoxy, ester, borate, azide, C=C triple bond, phosphate or combinations thereof.

[0061] Where the DCP is made up of P-hydroxy ester bonds, the DCP monomers may comprise di / poly-acids (e.g., sebacic acid, and / or adipic acid) and di / poly-glycidyl ethers, (e.g., one or more of poly(ethylene glycol) diglycidyl ether, bisphenol A diglycidyl ether, poly(dimethylsiloxane) diglycidyl ether, 1,4-butanediol diglycidyl ether, and / or 1,6-hexanediol diglycidyl ether).

[0062] The plurality of DCP monomers may have an acid to glycidyl ether molar ratio in the range of about 0.3:1 to about 0.9:1, about 0.3:1 to about 0.7:1, about 0.3:1 to about 0.5:1, about 0.5:1 to about 0.9:1 or about 0.7:1 to about 0.9:1.

[0063] Advantageously, where the acid to glycidyl ether molar ratio is the above ranges, the DCP formed may be terminated by glycidyl ether groups which can react with amino groups on the MOF to form a cross-linked structure.When the acid to glycidyl ether molar ratio is higher than about 0.9: 1, there may be an insufficient amount crosslinks to achieve desirable gel fraction.

[0064] When the acid to glycidyl ether molar ratio is lower than about 0.3:1, the plurality of DCP monomers may form shorter oligomer or polymer chains and the composite material may be undesirably brittle.

[0065] In a particular example:

[0066] (i) the MOF may comprise amino moieties; and

[0067] (ii) the DCP may comprises one or more glycidyl ether groups as terminal groups. In another particular example, the plurality of DCP monomers may comprise:

[0068] (a) a diacid and / or a polyacid; and

[0069] (b) a diglycidyl ether and / or a polyglycidyl ether,

[0070] at an acid to glycidyl ether molar ratio in the range of about 0.3:1 to about 0.9:1. The DCP monomers may comprise moieties that are capable of forming both the dynamic covalent bonds within the DCP and the one or more permanent covalent bonds between the DCP and the MOF.

[0071] The composite material may further comprise an additive.

[0072] Where the dynamic covalent bond has a high activation energy for breaking or forming, the additive may be a catalyst that reduces the activation energy. This may allow the composite material to be reprocessed at a milder condition such as a lower temperature.

[0073] Where the dynamic covalent bond is an ester bond (for example, a P-hydroxy ester bond), the additive may be a Bronsted base such as 2-methylimidazole, 1-methylimidazole or 4-dimethylaminopyridine. The additive may alternatively be a Lewis acid such as Zn(OAc)₂ or dibutyltin dilaurate.

[0074] Where the dynamic covalent bond is an imine bond, the additive may be an organic acid such as tri fluoroacetic acid. The additive may alternatively be a Lewis acid such as scandium(III) triflate.

[0075] The MOF may have a weight percentage in the range of about 5 weight% to about 90 weight%, about 15 weight% to about 90 weight%, about 40 weight% to about 90 weight%, about 50 weight% to about 90 weight%, about 75 weight% to about 90 weight%, about 5 weight% to about 75 weight%, about 5 weight% to about 50 weight%, about 5 weight% to about 40 weight%, about 5 weight% to about 15 weight%, about 15 weight% to about 75 weight% or about 40 weight% to about 50 weight%, based on the total weight of the composite material.The DCP may have a weight percentage in the range of about 10 weight% to about 95 weight%, about 30 weight% to about 95 weight%, about 60 weight% to about 95 weight%, about 10 weight% to about 60 weight% or about 10 weight% to about 30 weight%, based on the total weight of the composite material.

[0076] Where present, the additive may have a weight percentage in the range of about 0 weight% to about 1 weight%, about 0 weight% to about 0.1 weight%, about 0 weight% to about 0.01 weight%, about 0.01 weight% to about 1 weight%, about 0.1 weight% to about 1 weight% or about 0.01 weight% to about 0.1 weight%, based on the total weight of the composite material, provided that the weight percentages of the MOF, the DCP and the additive (when present) add up to 100 weight%.

[0077] Exemplary, non-limiting embodiments of a method of preparing a composite material will now be disclosed.

[0078] The method comprises the step of reacting a MOF with a DCP at an elevated temperature to form one or more permanent covalent bonds between the MOF and the DCP

[0079] In the reacting step, the elevated temperature may be a temperature in the range of about 50 °C to about 170 °C, about 120 °C to about 170 °C, about 150 °C to about 170 °C, about 100 °C to about 150 °C, about 120 °C to about 150 °C or about 50 °C to about 120 °C.

[0080] Alternatively, the elevated temperature may comprise two or more temperature periods, where a first temperature period is held at a “start temperature” and a second temperature period is held at an “end temperature”, with subsequent temperature periods being held at “start temperature” and “end temperature” relative to each other. The “start temperature” of a preceding temperature period may be lower than the “end temperature” of the succeeding temperature period. Therefore, the reacting step may further comprise a step of ramping the elevated temperature from the start temperature to the end temperature.

[0081] The start temperature may be a temperature in the range of 50 °C to about 150 °C, about 50 °C to about 100 °C or about 100 °C to about 150 °C.

[0082] The end temperature may be a temperature in the range of 130 °C to about 170 °C, about 130 °C to about 150 °C or about 150 °C to about 170 °C, provided that the end temperature is higher than the start temperature as described above.

[0083] The first temperature period may be undertaken for a duration in the range of about 5 hours to about 15 hours, about 5 hours to about 10 hours or about 10 hours to about 15 hours.

[0084] The reacting step may be undertaken for a duration in the range of about 1 hour to about 20 hours, about 8 hours to about 20 hours, about 10 hours to about 20 hours,about 6 hours to about 20 hours, about 6 hours to about 8 hours or about 15 hours to about 17 hours. The reacting step may be undertaken overnight.

[0085] The reacting step may be undertaken using a vacuum oven.

[0086] The reacting step may be undertaken in an inert atmosphere. The reacting step may be undertaken in an argon atmosphere.

[0087] The method may further comprise a step of synthesizing the MOF before the reacting step.

[0088] The synthesizing step may comprise reacting a metal precursor with organic ligands at an elevated temperature which may be the same or different from the elevated temperature used in the reacting step.

[0089] The metal precursor may contain a metal ion to allow for the formation of the coordination bonds. The metal ion may be a main group metal ion, a transition metal ion or a lanthanide metal ion as provided above. The metal ion may be formed from a metal selected from the group consisting of zirconium, zinc, nickel, manganese, copper, chromium, cadmium, iron, aluminum and combinations thereof.

[0090] The metal precursor may be a salt of the metal in the metal-containing nodes. The salt may be a halide salt. The salt may be a fluoride, chloride, bromide, iodide salt, or combinations thereof.

[0091] In the synthesizing step, the elevated temperature may be a temperature in the range of about 50 °C to about 150 °C, about 100 °C to about 150 °C or about 50 °C to about 100 °C.

[0092] The synthesizing step may be undertaken for a duration in the range of about 8 hours to about 36 hours, about 12 hours to about 36 hours, about 24 hours to about 36 hours, about 8 hours to about 24 hours or about 8 hours to about 12 hours.

[0093] The method may further comprise a step of polymerizing DCP monomers to form the DCP before the reacting step. The polymerizing step is conducted independently from the synthesizing step (if both steps are present) and may be done before, simultaneously with or after the synthesizing step (if both steps are present). Accordingly, the DCP monomers are not reacted directly with the MOF, or otherwise the desired composite material will not be formed.

[0094] The DCP monomers may comprise moieties that are capable of forming dynamic covalent bonds. The dynamic covalent bonds may be selected from the group consisting of:

[0095]

[0096] Therefore, the DCP monomers may comprise moieties selected from the group consisting of carboxylic acid, hydroxyl, carbonyl, amino, sulfide, sulfhydryl, amide, C=C double bond, epoxy, ester, borate, azide, C=C triple bond, phosphate or combinations thereof.

[0097] Where the DCP is made up of p-hydroxy ester bonds, the DCP monomers may comprise di / poly-acids (e.g., sebacic acid, and / or adipic acid) and di / poly-glycidyl ethers, (e.g., one or more of poly(ethylene glycol) diglycidyl ether, bisphenol A diglycidyl ether, poly(dimethylsiloxane) diglycidyl ether, 1,4-butanediol diglycidyl ether, and / or 1,6-hexanediol diglycidyl ether).

[0098] The method may comprise the step of selecting the plurality of DCP monomers such that the molar ratio of the acid to the glycidyl ether may be in the range of about 0.3:1 to about 0.9:1, about 0.3:1 to about 0.7:1, about 0.3:1 to about 0.5:1, about 0.5:1 to about 0.9:1 or about 0.7:1 to about 0.9:1.

[0099] In a particular example:

[0100] (i) the MOF may comprise amino moieties; and

[0101] (ii) the DCP may comprises one or more glycidyl ether groups as terminal groups. In another particular example, the plurality of DCP monomers may comprise:

[0102] (a) a diacid and / or a polyacid; and

[0103] (b) a diglycidyl ether and / or a polyglycidyl ether,

[0104] at an acid to glycidyl ether molar ratio in the range of 0.3:1 to 0.9: 1.

[0105] The DCP monomers may comprise moieties that are capable of forming both the dynamic covalent bonds within the DCP and the one or more permanent covalent bonds between the DCP and the MOF.

[0106] Therefore, the method may further comprise:

[0107] (i) a step of synthesizing the MOF before the reacting step; and / or(ii) a step of polymerizing a plurality of DCP monomers to form the DCP before the reacting step.

[0108] The method may further comprise a step of dispersing the MOF and the DCP together (i.e., in the same reaction vessel) before the reacting step.

[0109] The dispersing step may be undertaken in the presence of a solvent.

[0110] The solvent is not particularly limited as long as it can disperse or dissolve the MOF and the DCP without reacting to the MOF or the DCP.

[0111] The method may further comprise a step of homogenizing the MOF and the DCP together (i.e., in the same vessel) before the reacting step.

[0112] The homogenizing step may be undertaken in the presence of a solvent.

[0113] The solvent is not particularly limited as long as it can homogenize the MOF and the DCP without reacting to the MOF or the DCP.

[0114] The solvent used in the dispersing step and the solvent used in the homogenizing step may be independently selected from tetrahydrofuran, ethanol, ethyl acetate, acetonitrile, dichloromethane, chloroform or a combination thereof. The solvent used in the dispersing step and the solvent used in the homogenizing step may be the same or different.

[0115] Advantageously, the homogenizing step may make the MOF dispersed better. Therefore, the composite material may have a higher homogeneity and a higher gel fraction compared to a composite material formed without the homogenizing step. The homogenizing step may comprise ultrasonicating, vortexing, shaking, heating or combinations thereof of the MOF and the DCP.

[0116] Where a solvent is used as described above, the method may further comprise a step of removing the solvent by heating before the reacting step.

[0117] Advantageously, the heating step may concentrate the reaction mixture to enable more rapid reaction. Therefore, the composite material may be formed in a shorter duration and have a higher gel fraction compared to a composite material formed without the heating step.

[0118] The heating 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 heating may be undertaken at about a boiling point of the solvent.

[0119] The heating may be undertaken for a duration in the range of about 0.2 hours to about 6 hours, about 2 hours to about 6 hours, about 3 hours to about 6 hours, about 5 hours to about 6 hours, about 0.2 hours to about 5 hours, about 0.2 hours to about 3 hours or about 0.2 hours to about 2 hours.In the reacting step, the MOF and the DCP may have a weight ratio which is suitably selected based on factors such as:

[0120] (a) molecular weight of the monomer;

[0121] (b) desired molecular weight of the dynamic covalent polymer;

[0122] (c) critical chain entanglement molecular weight of the polymer;

[0123] (d) size and shape of the MOF; and / or

[0124] (e) degree of functionalization of the MOF.

[0125] Tn the reacting step, the MOF and the DCP may have a weight ratio in the range of about 0.05:1 to about 9:1, about 0.7:1 to about 1:1, about 0.5:1 to about 0.7:1 or about 0.7:1 to about 0.8:1.

[0126] Exemplary, non-limiting embodiments of an article will now be disclosed.

[0127] The article comprises the composite material as described herein.

[0128] The article may be in the form of a film, a sheet or a membrane.

[0129] The article may be formed directly from the method as described herein. Alternatively, the article may be formed from the composite material as described herein via further reactions or modification depending on the article to be formed.

[0130] Brief Description of Drawings

[0131] 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.

[0132] FIG. 1A

[0133] [FIG. 1 A] is a schematic illustration of a conventional composite material comprising a simple mixture / blend of a metal-organic framework (MOF) with a polymer matrix.

[0134] FIG. IB

[0135] [FIG. IB] is a schematic illustration of another conventional composite material comprising a functionalised MOF which is covalently attached to a polymer matrix.

[0136] FIG. 1C

[0137] [FIG. 1C] is a schematic illustration of another conventional composite material comprising a blend of MOF with a dynamic covalent polymer (DCP).FIG. ID

[0138] [FIG. ID] is a schematic illustration of another conventional composite material comprising a functionalised MOF which is connected to a DCP via dynamic covalent bonds.

[0139] FIG. IE

[0140] [FIG. IE] is a schematic illustration of a composite material according to an embodiment of the present disclosure comprising a MOF connected to a DCP via permanent covalent bonds.

[0141] FIG. IF

[0142] [FIG. IF] shows a non-exhaustive list of possible dynamic covalent bonds which may be used according to the present disclosure.

[0143] FIG. 2

[0144] [FIG. 2] provides a synthesis scheme to make an embodiment of the composite material as shown in FIG. IE.

[0145] FIG. 3

[0146] [FIG. 3] shows camera images demonstrating thermo-responsive behavior of PEO-S-BPA aqueous solution at two different temperatures.

[0147] FIG. 4

[0148] [FIG. 4] shows

[0149]

[0150] nuclear magnetic resonance (NMR) spectra of PEO-S during the synthesis of the same.

[0151] FIG. 5

[0152] [FIG. 5] shows ¹H NMR spectra of PEO-S-BPA during the synthesis of the same.

[0153] FIG. 6

[0154] [FIG. 6] shows ¹H NMR spectra of PDMS-S during the synthesis of the same. FIG. 7

[0155] [FIG. 7] shows Fourier-transform infrared (FT-IR) spectra of PEO-S and MMM-(PEO-S)

[0156] FIG. 8

[0157] [FIG. 8] shows FT-IR spectra of PEO-S-BPA and MMM-(PEO-S-BPA).FIG. 9

[0158] [FIG. 9] shows FT-IR spectra of PDMS-S and MMM-(PDMS-S).

[0159] FIG. 10

[0160] [FIG. 10] shows FT-IR spectra of PEO-S-BPA and X-PEO-S-BPA.

[0161] FIG. 11

[0162] [FIG. 11] shows an FT-IR spectrum of PEO-FTA.

[0163] FIG. 12

[0164] [FIG. 12] shows X-ray diffraction (XRD) analysis results for various samples obtained as described herein.

[0165] FIG. 13

[0166] [FIG. 13] shows TGA curve of MMM (PEO-S-BPA) 44.4% MOF in nitrogen. FIG. 14A

[0167] [FIG. 14A] shows TGA curve of UiO-66-NH2 MOF in air.

[0168] FIG. 14B

[0169] [FIG. 14B] shows TGA curve of MMM (PEO-S-BPA)|44.4% MOF in air.

[0170] FIG. 15A

[0171] [FIG. 15 A] shows camera images of results of mechanical recycling and film forming of MMM-(PEO-S).

[0172] FIG. 15B

[0173] [FIG. 15B] shows camera images of results of mechanical recycling and film forming of MMM-(PEO-S-BPA).

[0174] FIG. 15C

[0175] [FIG. 15C] shows camera images of results of mechanical recycling and film forming of X-PEO-S-BPA

[0176] FIG. 16

[0177] [FIG. 16] shows camera images of results of inability to mechanically recycle PEO-HA.FIG. 17

[0178] [FIG. 17] shows differential scanning calorimetry (DSC) graphs for mechanical recycling of MMM-(PEO-S-BPA)|44.4% MOF.

[0179] FIG. 18

[0180] [FIG. 18] shows concentration of methylene blue (MB) vs. time during a dye adsorption process at different temperatures.

[0181] FIG. 19

[0182] [FIG. 19] shows camera images of MB samples after 24 hours of dye adsorption at different temperatures.

[0183] FIG. 20

[0184] [FIG. 20] shows concentration of MB vs. time during a dye adsorption process for MOF, MMM-(PEO-S-BPA) and X-PEO-S-BPA.

[0185] FIG. 21

[0186] [FIG. 21] shows concentration of methyl orange (MO) vs. time during a dye adsorption process for MOF, MMM-(PEO-S-BPA) and X-PEO-S-BPA.

[0187] FIG. 22

[0188] [FIG. 22] shows concentration of Rhodamine B (RB) vs. time during a dye adsorption process for MOF, MMM-(PEO-S-BPA) and X-PEO-S-BPA.

[0189] FIG. 23

[0190] [FIG. 23] shows concentration of crystal violet (CV) vs. time during a dye adsorption process for MOF, MMM-(PEO-S-BPA) and X-PEO-S-BPA.

[0191] FIG. 24

[0192] [FIG. 24] shows concentration of MB vs. time during a dye adsorption process for a mixture of MB and MO as adsorbed by MMM-(PEO-S-BPA) or X-PEO-S-BPA.

[0193] FIG. 25

[0194] [FIG. 25] shows concentration of MO vs. time during a dye adsorption process for a mixture of MB and MO as adsorbed by MMM-(PEO-S-BPA) or X-PEO-S-BPA.

[0195] FIG. 26

[0196] [FIG. 26] shows concentration of MB vs. time during a dye adsorption process for a mixture of MB and RB as adsorbed by MOF, MMM-(PEO-S-BPA) or X-PEO-S-BPA.FIG. 27

[0197] [FIG. 27] shows concentration of RB vs. time during a dye adsorption process for a mixture of MB and RB as adsorbed by MOF, MMM-(PEO-S-BPA) or X-PEO-S-BPA.

[0198] FIG. 28

[0199] [FIG. 28] shows concentration of MB vs. time during a dye adsorption process for a mixture of MB and CV as adsorbed by MOF, MMM-(PEO-S-BPA) or X-PEO-S-BPA.

[0200] FIG. 29

[0201] [FIG. 29] shows concentration of CV vs. time during a dye adsorption process for a mixture of MB and CV as adsorbed by MOF, MMM-(PEO-S-BPA) or X-PEO-S-BPA.

[0202] FIG. 30

[0203] [FIG. 30] shows camera images of various dyes before and after a 7-hour dye adsorption process by MOF.

[0204] FIG. 31

[0205] [FIG. 31] shows camera images of various dyes before and after a 7-hour dye adsorption process by MMM-(PEO-S-BPA).

[0206] FIG. 32

[0207] [FIG. 32] shows camera images of various dyes before and after a 7-hour dye adsorption process by X-PEO-S-BPA.

[0208] Detailed Description of Drawings

[0209] FIG. 2

[0210] [FIG. 2] provides a synthesis scheme to make an embodiment of the composite material as shown in FIG. IE comprising two steps: (i) polymerization of a monomer containing two terminal acid moieties and another monomer containing two terminal epoxide moieties to form a linear epoxy-acid DCP with epoxide chain ends, (ii) reaction of the polymer formed in step (i) with a MOF to form a composite material with permanent covalent bonds between the MOF and DCP. The composite material may still be reprocessed due to the dynamic covalent bonds present in the DCP.Examples

[0211] 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.

[0212] Example 1 - Preparation of MOF-DCP Composites

[0213] The general process steps for preparing metal-organic framework (MOF) - dynamic covalent polymer (DCP) mixed matrix membrane (MMM) composites (see FIG. IE for structure, where the MOF 106 is functionalised to form permanent covalent bonds 112 with the polymer 102 and the polymer comprises dynamic covalent bonds 108 within itself) are described in Table 1 below and shown in FIG. 2.

[0214] Table 1. Process steps for preparation of MOF-DCP composite

[0215] Step Process Remarks

[0216] 1 Synthesis MOF The MOF should contain at least some ligand bearing at least one functional group capable of forming a dynamic covalent bond (see FIG. IF for examples) with the polymer.

[0217] The following parameters may be varied while keeping the present invention working:

[0218] • Functional group on MOF ligand

[0219] • MOF structure and porosity

[0220] • Percentage of functionalised ligand

[0221] • MOF particle size

[0222] UiO-66-NH₂ is exemplified in this example.

[0223] 2 Synthesis of DCP The DCP should have the following properties:

[0224] • It can be a linear dynamic covalent polymer chain or a crosslinked dynamic covalent network; and

[0225] • It can react with MOF to form permanent covalent bonds

[0226] The following parameters may be varied while keeping the present invention working:

[0227] • Structure of monomers

[0228] • Ratio of monomers

[0229] • Amount of end-groups

[0230] Steps:

[0231] 1. Synthesis of dynamic covalent polymer with excess functional groups for reacting with MOF

[0232] 2. Purification of polymer

[0233] Three different types of linear epoxy-acid DCPs with epoxide chain ends are exemplified in this example. 3 Synthesis of composite The MOF and the monomers should be carefully selected such that they can be reacted to form at least one type of

[0234]

[0235] permanent covalent bond.Hie ratio of MOF to monomers may be varied while keeping the present invention working.

[0236] Composites prepared from UiO-66-NH2 and three different epoxy-acid DCPs are exemplified in this example.

[0237] Steps:

[0238] 1. Sonicate a mixture of MOF and polymer in solvent for ~40 minutes.

[0239] 2. Shake the suspension for 30 minutes to ensure homogeneity

[0240] 3. Remove solvent at 70 °C under a stream of inert gas.

[0241] 4. Heat to 120 °C under inert atmosphere for 10 hours,

[0242]

[0243] then to 160 °C.

[0244] Hence, based on FIG. 2, to make the composites from UiO-66-NH2 and three different epoxy-acid DCPs, the two steps are: (i) polymerization of diacid and diglycidyl ether-containing polymers to form a linear epoxy-acid DCP with epoxide chain ends, (ii) reaction of the polymer formed in step (i) with UiO-66-NH2 to form a composite material with permanent covalent bonds between the MOF and DCP. The detailed synthesis protocol is provided below:

[0245] Synthesis of MOF UiO-66-NH2

[0246] 6 g of ZrCU (purchased from Strem Chemicals, Massachusetts, United States of America) and 4 g of 2-aminoterephtalic acid (purchased from TCI Chemicals, Tokyo, Japan) were added to a 1 L glass bottle, followed by 250 mL of acetic acid (purchased from TCI Chemicals, Tokyo, Japan) and 250 mL of DMF (purchased from Thermo Scientific Chemicals, Massachusetts, United States of America). The mixture was stirred until all solids had dissolved, then placed into an oven at 130 °C for 24 hours. The solids formed were collected by centrifugation for 5 minutes at 8000 rpm. The solvent was decanted and the solids were redispersed in acetone, followed by centrifugation for 5 minutes at 8000 rpm. The washing process was repeated twice. The solids were then redispersed in methanol (100 mL) and heated under reflux for 10 days. The UiO-66-NH2 MOF was collected by centrifugation for 5 minutes at 8000 rpm and dried in an oven at 60 °C for 24 hours.

[0247] Synthesis of PEO-S (1:0.6)

[0248] 9.0 g of poly(ethylene glycol) diglycidyl ether (PEO-DEG, n=approx. 22, purchased from TCI, Tokyo, Japan) was weighed and placed in an oven at 60°C overnight to ensure complete melting. Subsequently, 1.0 g of sebacic acid (Sb A, purchased from Sigma- Aldrich, Singapore, reacted at 1:0.60 molar ratio of PEO-DEG: SbA) was added to the fully melted PEO-DEG, and the mixture was stirred under Ar while gradually increasing the temperature to 110°C. Once the SbA was fully dissolved anda homogeneous mixture was achieved, 2 mol% of 1 -methylimidazole (MI, 14 pl, purchased from Sigma-Aldrich, Singapore) based on the total moles of PEO-DEG was added. The temperature was further increased to 120°C, and the reaction continued until all carboxylic acid groups had reacted with the epoxide groups. The conversion of the reaction was monitored using Proton nuclear magnetic resonance (¹H NMR) spectroscopy. Upon completion of the reaction, the mixture was allowed to cool. To purify the resulting polymer, the entire sample was dissolved in water and precipitated in diethyl ether. The mixture was then centrifuged at 10,000 rpm for 10 minutes, and this purification process was repeated three times. The final precipitate was dried in a vacuum oven at 60°C overnight. The resulting epoxy-acid polymer, PEO-S, contained free epoxide groups at the chain ends, with PEO segments as hydrophilic domains and SbA segments acting as a chain extender.

[0249] For PEO-S (1:0.7), the protocol was similar, but a 1:0.7 molar ratio of PEO-DEG: SbA was used instead.

[0250] Synthesis of PEO-S-BPA

[0251] For the synthesis of PEO-S-BPA, 5.4 g of PEO-DEG was weighed and placed in an oven at 60°C overnight to ensure complete melting. Next, 1.3 g of SbA (0.77:1 mol ratio of PEO-DEG: SbA) was added to the melted PEO-DEG, and the mixture was stirred under Ar while the temperature was increased to 110°C (Sample code I). After the SbA was fully dissolved, 2 mol% of MI (8 pl) based on the total moles of PEO-DEG was added. The temperature was raised to 120°C, and the reaction continued until all epoxide groups were reacted, as confirmed by1H NMR spectroscopy (Sample code II). Upon confirmation that no epoxide groups remained, an excess amount of bisphenol A diglycidyl ether (BPA-DEG, purchased from TCI, Tokyo, Japan, 1.4 g, 0.64:1 molar ratio of BPA-DEG: SbA) was added. The reaction continued under the same conditions until the desired epoxide content was achieved (Sample code III). After cooling, the polymer was purified by dissolving in water and precipitating in diethyl ether. The purification process was repeated three times, followed by drying in a vacuum oven at 60°C overnight. The final epoxy-acid polymer, PEO-S-BPA, had free epoxide groups at the chain ends, with PEO segments as hydrophilic domains and SbA segments as chain extenders. The key difference between PEO-S-BPA and PEO-S is the end-capping of PEO-S-BPA with BPA, a bulky aromatic group. Due to the hydrophilic and hydrophobic segments in the structure of PEO-S-BPA, the aqueous polymer solution showed thermo-responsive behavior (see FIG. 3).

[0252] Synthesis of PDMS-S

[0253] The synthesis of PDMS-S involved weighing 5.4 g of poly(dimethylsiloxane), diglycidyl (ether terminated, PDMS-DEG, Mn ~ 980, purchased from Sigma-Aldrich, Singapore) and adding 0.83 g of SbA (1: 0.75 molar ratio of PDMS-DEG: SbA), followed by stirring under Ar while increasing the temperature to 110°C. Oncea homogeneous mixture was formed, 2 mol% of MI (9 pl) based on the total moles of PDMS-DEG was added. The temperature was raised to 120°C, and the reaction was allowed to proceed until all carboxylic acid groups had reacted with the epoxide groups, as monitored by1H NMR. After completion, the mixture was cooled to obtain the epoxy-acid polymer PDMS-S, containing free epoxide groups at the chain ends, with PDMS segments as hydrophobic domains and SbA segments acting as a chain extender.

[0254] Synthesis of MMM-(PEO-S)-UiO-66-NH2-Q.7

[0255] To prepare MMM-(PEO-S), 2 g of PEO-S was dissolved in 7 ml of THF (purchased from VWR, Singapore) ), followed by the addition of 1.4 g of UiO-66-NH2(1: 0.7 polymer weight: MOF weight). The mixture was ultrasonicated for 40 minutes (10 minutes of ultrasonic treatment followed by 30 seconds of vortexing, 4 times). After the UiO-66-NH2was well dispersed, the mixture was shaken for 30 minutes and heated at 70°C under a stream of argon gas to remove the solvent. Once all traces of solvent were eliminated, the sample vial was vacuumed and refilled with argon for three cycles. The sample was then heated at 120°C overnight and subsequently at 160°C for 2 hours.

[0256] Synthesis of MMM-(PEO-S-BPA)-UiQ-66-NH2-0.8

[0257] For MMM-(PEO-S-BPA), 2 g of PEO-S-BPA was dissolved in 8 ml of THF, and 1.6 g of UiO-66-NH2(1: 0.8 polymer weight: MOF weight) was added. The mixture was ultrasonicated for 40 minutes (10 minutes of ultrasonic treatment followed by 30 seconds of vortexing). After ensuring well dispersion, the mixture was shaken for 30 minutes, then heated at 70°C under a stream of argon to remove the solvent. The sample vial was vacuumed and refilled with argon for three cycles, and heated at 120°C overnight followed by 160°C for 2 hours.

[0258] Synthesis of MMM-(PDMS-S)

[0259] MMM-(PDMS-S) was synthesized by dissolving 0.25 g of PDMS-S in 1 ml of THF, followed by the addition of 0.18 g of UiO-66-NH2(1:0.7 polymer weight: MOF weight). The mixture was ultrasonicated for 30 minutes (10 minutes of ultrasonic treatment followed by 30 seconds of vortexing). After dispersion, the mixture was shaken for 30 minutes and heated at 70°C under argon to remove the solvent. The sample vial was vacuumed, purged with argon for three cycles, and heated at 120°C overnight and 160°C for 2 hours.

[0260] Additional samples were prepared as described in more detail below, where the ratio of polymer weight: MOF weight was varied from 1: 0.6 to 1:0.9.Comparative Example 1 - Synthesis of Samples without MOF or Dynamic Covalent Bond

[0261] Synthesis of PEO-HA

[0262] To investigate the effect of dynamic bonding on the structure and properties, a control sample without dynamic bonds was synthesized. 3.60 g of PEO-DEG was weighed and melted in an oven at 60°C overnight. After that 0.40 g of hexamethylene diamine (HA, purchased from TCI, Tokyo, Japan, 1: 1 molar ratio of PEO-DEG: HA) was added to the melted PEO-DEG, and the mixture was stirred at 70°C. However, after one hour, the mixture turned into an uncontrolled gel.

[0263] Synthesis of X-PEO-S-BPA

[0264] To synthesize X-PEO-S-BPA, 0.55 g of PEO-S-BPA was dissolved in 2 ml of THF, and 0.004 g of amine crosslinker tris(2-aminoethyl)amine (purchased from TCI, Tokyo, Japan) was added. The mixture was stirred and shaken for 30 minutes, after which the solvent was evaporated at 70°C. The sample vial was vacuumed, purged with argon for three cycles, and then heated at 120°C overnight.

[0265] Example 2 - Characterisation of Samples

[0266] NMR results

[0267] Solution-state ¹H NMR spectra were recorded on a JEOL ECA-II 500 (500 MHz) or a JEOL ECZL 400 (400 MHz) and were referenced to residual non-deuterated solvent peaks in CDCl₃ (dH= 7.26) of D₂O (dH= 4.79). Data are reported as follows: chemical shifts (dH, reported in ppm), integration, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, br = broad, m = multiplet), and coupling constants (J, reported to the nearest 0.1 Hz). The ¹H NMR spectra were used to quantify residual epoxide during reactions, serving as a measure of reaction conversion.

[0268] ¹H NMR spectra of PEO-S during synthesis procedure are shown in FIG. 4 and the percentage of epoxide groups remained is shown in Table 2.

[0269] Table 2. Percentage of epoxide groups remained vs. reaction time of PEO-S TIME PERCENTAGE OF EPOXIDE REMAIN

[0270] (HOUR) (%)

[0271] 0 100

[0272] 1 77

[0273] 2 45

[0274]

[0275] 2.5 26

[0276] ¹H NMR spectra of PEO-S-BPA during synthesis procedure are shown in FIG. 5 and the percentage of epoxide groups remained is shown in Table 3.Table 3. Percentage of epoxide groups remained vs. reaction time of PEO-S-BPA TIME SAMPLE COMPONENTS PERCENTAGE OF EPOXIDE (HOUR) CODE > > REMAIN (%)

[0277] 0PEO-DEG PEO-DEG1001I PEO-DEG i SbA252II PEO-DEG + SbA02.5 III PEO-DEG + SbA + 27

[0278]

[0279] BPA-DEG

[0280] *H NMR spectra of PDMS-S during synthesis procedure are shown in FIG. 6 and the percentage of epoxide groups remained is shown in Table 4.

[0281] Table 4. Percentage of epoxide groups remained vs. reaction time of PEO-S-BPA TIME PERCENTAGE OF EPOXIDE REMAIN (%)

[0282] (HOUR)

[0283]

[0284] 0 100

[0285] 1 67

[0286]

[0287] 2 48

[0288] GPC results

[0289] Gel Permeation Chromatography (GPC) was performed in HPLC grade THF using the Agilent 1260 Infinity II GPC / SEC System with refractive index detector and calibration was performed using monodisperse polystyrene standards. GPC was used to measure the number-average and weight-average molecular weights of the polymers.

[0290] The GPC results for samples prepared are shown in Table 5 below.

[0291] Table 5. GPC results for polymers

[0292] Samples Mn (g / mol) Mw (g / mol) PDI PEO-DEG 1248 1983 1.58 PEO-S 3704 5926 1.60

[0293]

[0294] PEO-S-BPA 6321 12659 2.00

[0295] Gel fraction tests

[0296] Gel fraction test was done to ensure that the MMM composite samples have completely crosslinked.Approximately 30 mg of each synthesized sample was placed in a vial, and 2 ml of THF was added. The samples were heated at 70°C for 2 hours, after which the solvent was removed, and the remaining solid was dried and weighed. The gel fraction (GF) was calculated using the formula (1):

[0297] IVf-H',

[0298] 6F — — - X 100 (1)

[0299]

[0300] where Wf is the final weight of the remaining sample and wt is the initial weight of the sample. To ensure that the gel fraction primarily resulted from crosslinking effects of MOF-NH2 and the amine crosslinker, and not the other side reactions, linear polymeric samples were subjected to the same MMM synthesis procedure without a crosslinking agent, and their GF was measured. The results are presented in Table 6.

[0301] Table 6. Gel fraction (GF) for different samples

[0302] SAMPLE Ratio of UiO-66-NH₂ UiO-66-NH₂ wt% GF(%)

[0303] 0.6 37.5 56.2 0.7 41.1 63.1 MMM (PEO-S (1:0.6))

[0304] 0.8 44.4 69.2 0.9 47.4 71.0 0.6 37.5 56.4 MMM (PEO-S (1:0.7)) 0.7 41.1 69.5 0.8 44.4 66.3 0.6 37.5 61.3 0.7 41.1 63 MMM (PEO-S-BPA)

[0305] 0.8 44.4 72.9 0.9 47.4 71.1 MMM (PDMS-S) 0.7 44.4 73.9 X-PEO-S-BPA 0 0 60.8 PEO-S 0 0 0 PEO-S-BPA 0 0 0 PDMS-S 0 0 0

[0306]

[0307] PEO-HA 0 0 86.3aRatio of MOF:polymer MMM,bwt% of MOF as w.r.t. total mass of MMM

[0308]

[0309] FTIR results

[0310] Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) was performed using a Bruker Vertex 80v spectrometer. Samples were scanned from 400 cm'1to 4000 cm'1for 64 scans.

[0311] Diminishing epoxide peaks (~800 to 900 cm'1) and appearance of MOF peaks during the formation of MMM from PEO-S, PEO-S-BPA and PDMS-S are shown in FIGs.7 to 9, respectively. FIG. 10 demonstrates the FT-IR spectra of PEO-S-BPA and X-PEO-S-BPA, while FIG. 11 shows the spectrum of PEO-HA.

[0312] XRD results

[0313] X-Ray Diffraction (XRD) data were collected using a Bruker D8-Advance X-ray powder diffractometer with Cu Ka radiation, at a resolution of 0.02° and a scan rate of 0.1-0.5 s / point. XRD confirmed the presence and structural integrity of MOF in the MMMs.

[0314] FIG. 12 demonstrates the XRD analysis results for different MMMs, indicating that MOF was successfully integrated into the membranes.

[0315] TGA results

[0316] Thermogravimetric analysis (TGA) was carried out with a TA Instruments Q500 in both air and nitrogen. 5 - 10 mg of the samples were loaded into alumina pans. TGA was run at the rate of 5 °C min'1, under an air flow of 60 mE min'1, from room temperature to 650 °C and 800 °C in air and nitrogen respectively.

[0317] FIG. 13 shows TGA of MMM (PEO-S-BPA)|44.4% MOF in nitrogen, indicating stability up to more than 200 °C.

[0318] TGA in Air: Quantification of defects in MOF

[0319] TGA of UiO-66-NH2 in air is shown in FIG. 14A. Given that UiO-66-NH2 decomposes at 300 °C, before the MOF nodes have completely dehydroxylated, the quantification linker per Zr6 node using TGA is not as accurate as with other zirconium MOFs. Therefore, the weight at 250 °C (96 weight%) was used to calculate the amount of linker. Given that the residual weight was 43.3 weight%, the weight % loss due to ligand decomposition was estimated to be 52.7 weight%, thus giving a ligand / Zr ratio of 0.82, or 4.9 linkers per Zre, which aligned well with existing literature syntheses.

[0320] TGA in Air: Quantification of MOF in MMM

[0321] Assuming that all solvent molecules are driven off from the MMM at 100 °C, the weight percentage of MOF was normalized to the dry MMM starting at 100 °C. From the TGA of the pure MOF, the molecular weight of the MOF, including coordinated water, was calculated to be approximately 1693 g / mol per Z17, node, or 282.15 per Zr atom. The calculation was based on the assumption that all uncoordinated water had been driven off at 100 °C.

[0322] The weight % of MOF in the MMMs was then calculated using the formula:

[0323] residual weight % × 282.15

[0324]

[0325] Mw[ZrO2]The TGA of MMM (PEO-S-BPA)|44.4% MOF is shown in FIG. 14B. The estimated experimental MOF weight% was calculated to be 42.4%, which was similar to the amount of MOF added.

[0326] DSC results

[0327] Differential Scanning calorimetry (DSC) was performed with a TA instrument Q20.

[0328] 3 to 5 mg of the samples were loaded into aluminum hermetic pans. First, an initial scan from room temperature to 150 °C was carried out to remove any thermal history of the samples. Then, the samples were cycled from -80 °C to 150 °C for 2 cycles. Nitrogen flow rate and heating rate were set at 50 mL min'1and 20 °C min'1respectively. DSC illustrated differences before and after crosslinking.

[0329] DSC results for polymers and MMMs are presented in Table 7.

[0330] Table 7. Tg, Tc, and Tm results from DSC test for the polymers and MMMs Sample Tg (°C) Tc (°C) Tm (°C)

[0331] Linear Poly mers

[0332] PEO-S -47.6 — 32.4

[0333] PEO-S-BPA -49.5 -15.5 25.5

[0334] PDMS-S

[0335] Crosslinked Polym ers / MMMs

[0336] X-PEO-S-BPA -44.8 -11.8 31.0

[0337] MMM (PEO-S) 41.1% MOF 40.8

[0338] MMM (PEO-S-BPA) 44.4% MOF -47.5 -12.4 36.1

[0339] MMM (PDMS-S) 44.4% MOF

[0340]

[0341] Example 3 - Mechanical Recycling Experiments

[0342] Mechanical recycling of different MMMs

[0343] Crosslinked samples, including MMM-(PEO-S), MMM-(PEO-S-BPA), MMM-(PDMS-S), and X-PEO-S-BPA, were mechanically recycled using the following procedure. The sample was placed between two PTFE non-stick sheets and formed into a film using a 0.5 mm thick mold. The samples were preheated for 10 minutes, then hot-pressed for 20 minutes at 160°C under 5 bar pressure. A control sample (PEO-HA) without dynamic bonds was also hot-pressed using a similar procedure. FIGs. 15A to 15C show the mechanical recycling of the MMMs. Samples containingcovalent adaptable networks (CANs) demonstrated good film formation and mechanical recyclability, whereas PEO-HA could not be hot-pressed, indicating that mechanical recyclability is driven by the epoxy-acid CANs (see FIG. 16).

[0344] Repeated mechanical recycling of MMM-(PEO-S-BPA)|44.4% MOF

[0345] To demonstrate the repeated mechanical recycling of MMM-(PEO-S-BPA)|44.4% MOF, the MMM was recycled 5 times, and its crosslinking and thermal properties were investigated through this process.

[0346] For each mechanical recycling, the sample was placed between two PTFE non-stick sheets and formed into a film using a 0.5 mm thick mold. The sample was preheated for 5 minutes, then hot-pressed for 5 minutes under 5 bar pressure at 160°C, followed by 20 minutes under 50 bar pressure at 160°C.

[0347] DSC and gel fraction results for the mechanical recycling of MMM-(PEO-S-BPA), in which MRU indicates mechanical recycling for X times, are reported in Table 8 and FIG. 17. Gel fraction was performed on the mechanically recycled samples using the same procedure as described in Example 2. The Tm, Tc and gel fraction of MMM-(PEO-S-BPA) did not change significantly even after 5 mechanical recycles, indicating the stability of the MMM-(PEO-S-BPA) during the recycling process. This contrasts with samples with dynamic bonds between the MOF and the dynamic covalent polymer, in which the gel fraction decreased to 0% after multiple hot-pressing cycles.

[0348] Table 8. DSC and gel fraction results for mechanical recycling of MMM-(PEO-S-BPA)|44.4% MOF

[0349] Sample Tc (°C) Tm (“C) GF

[0350] -12.4 36.1 64 ± 3

[0351] MMM-(PEO-S-BPA)-MR1 -9.6 36.2 66 ± 2 MMM-(PEO-S-BPA)-MR3 -10.0 36.3 63 ± 3

[0352]

[0353] MMM-(PEO-S-BPA)-MR5 -9.5 36.4 60 ± 7

[0354] Example 4 - Dye Adsorption Tests

[0355] Dye adsorption was monitored with Ultraviolet Visible (UV-Vis) Spectroscopy, performed on using a Shimadzu UV-2501PC spectrophotometer.

[0356] Temperature responsiveness tests

[0357] The temperature responsiveness of the synthesized MMMs was examined by studying methylene blue (MB, purchased from TCI, Tokyo, Japan) adsorption at different temperatures (FIGs. 18 and 19). Therefore, all the dye adsorptions for MMMs were done at 75 °C as an optimum temperature.

[0358] Dye adsorption tests were conducted using two approaches: single dye adsorption and mixed dye adsorption. Aqueous solutions of single dyes, including MB, methylorange (MO, purchased from TCI, Tokyo, Japan), Rhodamine B (RB, purchased from TCI, Tokyo, Japan), and crystal violet (CV, purchased from TCI, Tokyo, Japan) at 10 pM concentrations, were prepared. The mixed dye adsorption contained mixtures of MB (5 pM) with MO (5 pM), RB (5 pM), and CV (5 pM).

[0359] Single-dye adsorption

[0360] For MB dye, X-PEO-S-BPA (7.6 mg) exhibited minimal adsorption capacity, achieving only about 10% dye uptake. In contrast, the MOF (5.4 mg) fully adsorbed the MB dye. The MMM-(PEO-S-BPA) (13 mg) displayed intermediate behavior, with an adsorption efficiency of approximately 60%. For MO dye, all sorbents showed similar and high adsorption capacities, with about 80% of the dye being adsorbed. The adsorption trend for RB was similar to that of MB, where X-PEO-S-BPA exhibited low adsorption (around 30%), while MOF absorbed nearly 80% of the dye. The MMM (PEO-S-BPA) achieved an adsorption rate of approximately 60%, representing an intermediate performance between X-PEO-S-BPA and MOF. For CV dye, all sorbents exhibited similar adsorption capacities, with each adsorbing roughly 50% of the dye. The results are shown in FIGs. 20 to 23, with photographs in FIGs. 30 to 32.

[0361] Mixed-dye adsorption

[0362] In the dye mixture experiments, the MMM-(PEO-S-BPA) consistently demonstrated a uniform adsorption rate of approximately 60% for all dyes. However, the performance of X-PEO-S-BPA and MOF varied significantly depending on the specific dye and mixture composition. In the MB and MO mixture, X-PEO-S-BPA selectively adsorbed MO, leaving the MB dye unadsorbed. This selective adsorption pattern was observed in other dye mixtures as well, where X-PEO-S-BPA failed to adsorb MB but effectively adsorbed the other dyes. Conversely, MOF exhibited rapid and complete adsorption of both MB and MO dyes in the mixture, as indicated by the initial readings. However, for mixtures containing RB and CV dyes, the adsorption efficiency of MOF decreased to approximately 70% and 60%, respectively. The results are shown in FIGs. 24 to 32.

[0363] Industrial Applicability

[0364] The composite material of the disclosure may be used in a variety of applications such as membranes, adsorption, separation, catalysis or environmental remediation. 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 composite material comprising a metal-organic framework (MOF) connected to a dynamic covalent polymer (DCP) via a permanent covalent bond.

2. The composite material of claim 1, wherein the MOF comprises a main group metal ion, a transition metal ion or a lanthanide metal ion.

3. The composite material of claim 1 or 2, wherein the MOF comprises a plurality of organic ligands, each organic ligand independently having two or more moieties selected from amino moieties, carboxylic acid moieties or a derivative thereof, epoxides or a combination thereof.

4. The composite material of claim 3, wherein each organic ligand is independently selected from terephthalic acid optionally functionalised with an amino, a hydroxyl or mercapto group, trimellitic acid, trimesic acid, functionalised bipyridine, functionalised imidazole or a combination thereof.

5. The composite material of any one of claims 1 to 4, wherein the DCP comprises dynamic covalent bonds selected from the group consisting of:and combinations thereof.

6. The composite material of any one of claims 1 to 5, wherein the DCP is not cross-linked.

7. The composite material of any one of claims 1 to 6, wherein the DCP comprises one or more p-hydroxy ester bonds.

8. The composite material of any one of claims 1 to 7, wherein the permanent covalent bond connecting the MOF and the DCP is a C-N bond.

9. The composite material of any one of claims 1 to 8, further comprising an additive.

10. The composite material of any one of claims 1 to 9, wherein the MOF has a weight percentage in the range of 5 weight% to 90 weight%, based on the total weight of the composite material.

11. A method of preparing a composite material, comprising the step of reacting a MOF with a DCP at an elevated temperature to form one or more permanent covalent bonds between the MOF and the DCP.

12. The method of claim 11, further comprising:(i) a step of synthesizing the MOF before the reacting step, and / or(ii) a step of polymerizing a plurality of DCP monomers to form the DCP before the reacting step.

13. The method of claim 11 or 12, further comprising a step of homogenizing the MOF and the DCP in the presence of a solvent before the reacting step, and optionally followed by a step of at least partially removing the solvent by heating before the reacting step.

14. The method of any one of claims 11 to 13, wherein:(i) the MOF comprises amino moieties; and(ii) the DCP comprises one or more glycidyl ether groups as terminal groups.

15. The method of any one of claims 12 to 14, wherein the plurality of DCP monomers comprise:(a) a di acid and / or a polyacid; and(b) a diglycidyl ether and / or a polyglycidyl ether,at an acid to glycidyl ether molar ratio in the range of 0.3: 1 to 0.9: 1.

16. An article comprising the composite material of any one of claims 1 to 10.

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