Initiator-induced composite porous membrane fabrication method

Abstract

The present invention relates to a method for producing a membrane, wherein the method is a simple and cost-effective membrane production method. The method comprises the steps of mixing at least one monomer and / or oligomer with a pore- forming agent, adding an initiator and a substrate, and activating the initiator. The invention further relates to a membrane comprising a substrate coated with a cross-linked monomers and / or cross-linked oligomers having radical polymerizable functional groups and use thereof.

Description

[0001] 84424PC01

[0002] 1

[0003] INITIATOR-INDUCED COMPOSITE POROUS MEMBRANE FABRICATION METHOD

[0004] Technical field of the invention

[0005] The present invention relates to a method for producing a membrane, specifically a cost-efficient and simple method to fabricate membranes for a membrane contactor and separation process. The initiator-induced phase separation is applied for the pore formation of the membrane. By fusing the photopolymer with the fibrous substrate, membranes with various thicknesses and geometries with mechanical strength can be obtained. In particular, the present invention relates to a method for producing a membrane comprising the steps of: a) providing at least one monomer and / or oligomer, b) optionally, mixing the at least one monomer and / or oligomer with a cross-linker, c) adding at least one pore-forming agent to the mixture comprising the monomer and / or oligomer, d) adding an initiator and at least one substrate, followed by e) activating the initiator.

[0006] Background of the invention

[0007] Although membrane technologies are well-established in the water industry, there is an urgent need for future membrane fabrication methods to become more versatile and sustainable, and to expand their applications across various fields. The future development of membrane production methods should focus on several key aspects: scalability through simple and reliable production methods; more sustainable production by reducing or eliminating harmful substances; and cost reduction for standard membrane products.

[0008] The production of membranes today relies on a limited selection of methods and materials that have limited the use of membranes in applications. The most common method for producing commercial porous polymer membranes involves separating homopolymer solutions into phases, a process commonly referred to as phase inversion. A typical phase inversion process can be conducted by immersing 84424PC01

[0009] 2 the polymer solution in a non-solvent bath, known as non-solvent-induced phase separation (NIPS). Through the exchange of solvent, phase separation is induced, and pores can be formed in the polymer matrix. In this method, phase separation can also be triggered by changing the temperature or by evaporating the solvents. Interfacial polymerization is another common method for the fabrication of nanofiltration (NF) and reverse osmosis (RO) membranes. In the instance of polyamide membrane fabrication, porous substrates soaked in an aqueous amine solution are treated with a non-polar solvent containing acyl chloride, initiating polymerization on the substrate surface.

[0010] The process of membrane fabrication currently requires extensive use of costly and potentially hazardous solvents, such as DMSO and DMF (WO16081541 Al). This not only challenges the adherence to tightening environmental regulations but also escalates the overall cost of production. Moreover, expanding the versatility of membranes necessitates advancements in their stability and surface characteristics. For instance, hydrophobic membranes are essential for various contactor processes, including membrane distillation and oil-water separation. Conversely, membranes with high hydrophilicity are sought after for their high flux and anti-fouling capabilities, enhancing their performance in numerous applications.

[0011] Photopolymerization is increasingly recognized in the realm of membrane fabrication, owing to its straightforwardness and scalability. The process enables the formation of membranes with just a few minutes of UV light exposure, streamlining production. It involves the curing of liquid monomers or oligomers when exposed to a light source of a particular wavelength, leading to the creation of thermoset polymers. This method is widely used to manufacture materials for various applications, including thin films, coatings, 3D printing, dental applications, and electronics, among others.

[0012] There have been reports of utilizing photopolymerization in mixtures of photopolymers and pore-forming agents, leading to a process where the mixture undergoes polymerization-induced phase separation (PIPS) (US2022288538 Al). By removing the pore forming agents, materials with microporous structures can be obtained. With this technique, the porosity and surface properties of the materials can be tuned by varying the ratio between the polymer and the poreforming agent and changing the composition of the starting material. 84424PC01

[0013] 3

[0014] Hence, an improved membrane fabrication method would be advantageous, and in particular a more efficient and cost-effective membrane fabrication method would be advantageous.

[0015] Summary of the invention

[0016] Thus, an object of the present invention relates to providing a simple and cost- effective membrane fabrication method suitable for scaling. In particular, it is an object of the present invention to provide a membrane fabrication method that solves the above-mentioned problems of the prior art with high costs, complex manufacturing processes and use of harmful substances, such as DMSO and DMF. The present invention offers high versatility in the composition, membrane geometry, pore size, and porosity of membranes. This approach allows for wide range of surface functionalities with varied hydrophobicity, hydrophilicity, and functional groups, catering to a broad spectrum of applications. The resulting membranes from present invention have superior chemical and thermal stability. Another object of the present invention relates to obtaining a membrane that is more resistant to mechanical stress than asymmetrical membranes obtained using the methods described in the prior art. The membrane of the present invention is preferably symmetrical.

[0017] The membrane fabrication method of the present invention results in a membrane best described as a fiber-reinforced polymer composite material. What sets this invention apart is the innovative fusion of the induced polymerization process, by using a non-polymerizable pore forming agent, such as C4-C12 alcohol as poreforming agent, and the fibrous substrate. At the same time, the polymer interpenetrated into the fibrous substrate to create a uniform membrane material. The porous nature is achieved via a polymerization-induced phase separation process, preferably using UV, between the polymers and the non-polymerizable pore forming agent, such as C4-C12 alcohol, and the fibrous substrate provides the strength and the final structure of the membrane.

[0018] This invention can cover a wide range of polymer and fibrous materials. The polymers that can be used in this method are e.g., polyacrylate, polyurethane, polydimethylsiloxane, etc. and the fibrous substrate can include ceramic fibers, glass fibers, polymer fibers, such as polypropylene (PP), polyethylene (PE), cellulose fibers, etc. Different non-polymerizable pore forming agents can be used 84424PC01

[0019] 4 for the pore-forming process. Depending on the membrane application, the desired functionalities can be achieved (such as high hydrophobicity) by changing the combination of the different components. Different membrane porosity can be achieved by varying the proportion of the pore forming agent. The present method can produce membranes in a more efficient and economical way, furthermore, the method does not require a large solvent consumption like the traditional methods. The present invention stands out due to its simplicity and eco-friendliness when juxtaposed with other membrane fabrication methods. Additionally, it offers a more cost-efficient solution while ensuring robustness and adaptability in operation.

[0020] Thus, one aspect of the invention relates to a method for producing a membrane comprising the steps of: a) providing at least one monomer and / or oligomer, b) optionally, mixing the at least one monomer and / or oligomer with a cross-linker, c) adding at least one pore-forming agent to the mixture comprising the monomer and / or oligomer, d) adding an initiator and at least one substrate, followed by e) activating the initiator.

[0021] Another aspect of the present invention relates to a membrane comprising a substrate coated with a porous polymer composed of cross-linked monomers and / or cross-linked oligomers having radical polymerizable functional groups, such as acryloyls, epoxides, and isocyanates.

[0022] Yet another aspect of the present invention is to provide use of the membrane according to the invention for electrochemical membrane processes, such as electrodialysis, electro filtration or electro osmosis, for concentration gradient, such as dialysis, gas separation or pervaporation, for thermal gradient, such as membrane distillation, membrane assisted crystallization or thermally assisted reverse osmosis, for pressure gradient, such as reverse osmosis, nanofiltration, ultrafiltration, microfiltration, oil water separation, or dairy separation. 84424PC01

[0023] 5

[0024] Brief description of the figures

[0025] Figure 1 shows images of membranes generated using the membrane fabrication method of the present invention. A) Image of a hydrophobic flat sheet membrane fabricated using the invented method, composed of cellulose fibrous substrate with a 40wt% resin to 60wt% porogen (1-decanol) ratio. B) Photograph showing the contact angle of water droplets on the surface of the produced hydrophobic flat sheet membrane.

[0026] Figure 2 shows stress-strain curve for the cellulose fiber supported and unsupported membranes, synthesized with 40wt% / 60wt% resin to 1-decanol ratio.

[0027] Figure 3 shows stress-strain curves for the cellulose fiber supported membranes produced with 45wt%, 40wt% and 35wt% resin composition. The test for each membrane has been repeated 2 to 3 times to minimize deviation.

[0028] Figure 4 shows the impact of the resin to porogen ratio on membrane structure as determined by capillary flow porometry. A) Membrane thickness variation ranging from 150 pm to 300 pm. B) Relationship between resin to porogen ratio and membrane porosity, showing a decrease in porosity from 78% to 68% as the resin to porogen ratio increases from 35wt% / 65wt% to 45wt% / 55wt%. C) Triple determination capillary flow porometry using Porofill as a wetting agent for samples Ml, M2, and M3 (from left to right). The gas flow through the membrane pores increases due to the increase of the pressure and de-wetting of the pores. D): Corresponding pore size diameters derived from Figure 4C. The membrane pore size distribution is characterized by the gas flow percentage increase at a specified applied pressure. E) Uniformity of pore size distribution across membranes with various resin to porogen ratios, where the difference between maximum and mean pore sizes remains within 100 nm, the mean pore size decreases, dropping from about 800 nm to 500 nm with an increase of resin to porogen ratio from 35wt% / 65wt% to 45wt% / 55wt%.

[0029] Figure 5 shows performance evaluation of membranes with different resin to porogen ratios using Direct Contact Membrane Distillation (DCMD). Graphs A), C), and E) depict the flux in liters of permeate per square meter of membrane area per hour (LMH) over time in minutes (x-axis), illustrating an increase in flux from 5.4-17.8 LMH to 7.44-26.7 LMH as the temperature rises from 50°C to 80°C for membranes Ml to M3, respectively. Graphs B), D), and F) show the permeate conductivity in pS / cm over time in minutes, demonstrating a reduction to below 2 84424PC01

[0030] 6 pS / cm indicating nearly 100% salt removal, which emphasizes the excellent desalination capabilities of the membranes.

[0031] Figure 6 shows flux and permeate conductivity of the membrane generated using ceramic fiber as the fibrous substrate (thickness: 2mm) during membrane distillation under varying temperatures. A) Flux of the membrane in LMH over time, showing an increase from approximately 3 LMH to 11 LMH as the feed temperature rises from 50°C to 90°C. B) Permeate conductivity measured in pS / cm, indicating a reduction from approximately 66000 pS / cm in the initial feed solution to about 2 pS / cm, demonstrating the membrane's excellent desalination capabilities by nearly removing 100% of the salt ions.

[0032] Figure 7 shows performance of the membrane generated using a non-woven polypropylene fiber as the fibrous substrate in a membrane distillation (MD) process. A) The membrane maintained a stable flux of approximately 7 LMH throughout the test period, showing consistent performance at a heater temperature of 70°C. B) High desalination capability is demonstrated with initial feed solution conductivity of about 66000 pS / cm reduced to below 10 pS / cm after the distillation process, indicating effective salt removal.

[0033] Figure 8 shows results of evaluating surface properties of membranes surfaces. A) The contact angle for the membrane surface from ceramic fiber exceeds 140°, demonstrating significant hydrophobicity. B) Similarly, the membrane surface from cellulose fiber also shows a contact angle above 140°, and C) the membrane surface from polypropylene fiber shows a contact angle around 139°, confirming the achievement of a hydrophobic surface using the present invention.

[0034] Figure 9 shows pore size analysis of membranes generated using cellulose or ceramic fibers as the fibrous substrate, as determined by capillary flow porometry. The data reveals that membranes incorporating cellulose fiber have a mean pore size of approximately 650 nm, with a maximum pore size within 700 nm. In contrast, membranes made with ceramic fiber feature smaller pores, with a mean pore size around 55.84 nm and a maximum pore size of about 182.7 nm.

[0035] Figure 10 shows contact angle measurement illustrating the hydrophilicity of the membrane surface obtained using the method of the present invention. The contact angle is approximately 76°, confirming the successful creation of a hydrophilic surface.

[0036] Figure 11 shows comparison of water flux in the hydrophilic membranes with different resin to porogen ratios of 40wt% / 60wt% (60 / 40) and 60wt% / 40wt% 84424PC01

[0037] 7

[0038] (40 / 60). The membrane with a 40% resin to porogen ratio shows a significantly higher water flux, approximately 367.7 LMH bar1, compared to the 60% resin to porogen ratio which demonstrates about 28.2 LMH bar1.

[0039] Figure 12 shows images of two nonwoven materials: A) Glass fiber and B) melt blown polypropylene, highlighting differences in fiber packing and surface texture. Figure 13 shows the effect of the porogen (polypropylene glycol (PPG)) concentration on membrane pore size. As the porogen loading increases from 60wt% to 80wt%, the average pore size grows from 85 nm to 333 nm.

[0040] Figure 14 shows the permeate flux and conductivity of a membrane generated using 70% of the porogen (polypropylene glycol (PPG)). A) Permeate flux vs. time for the membrane in a crossflow MD module (50 g L- 1NaCI; feed / permeate 70 / 15 °C), showing a stable flux of ~10 LMH over 8 h. B) Permeate conductivity vs. time during the same run, stabilizing at ~40 pS cm- 1while the feed is 67090 pS cm- 1, corresponding to ~99.94% salt rejection.

[0041] Figure 15 shows pictures of a membrane used in a pressure filtration experiment using bovine heamoglobin (BH) as the target solute. A) Picture of the membrane on the active filtration side with a red heamoglobin coat. B) Picture of the permeate side of membrane without signs of heamoglobin passing through.

[0042] Figure 16 shows results from a pressure filtration experiment using RuBisCo as the target solute. A) SDS-PAGE of spinach juice feed. B) SDS-PAGE of filtered spinach juice with clear signs of filtration of green particulates and unwanted compounds. C) SDS-PAGE baseline of RuBisCo bands. D) Flux graph of filtration of spinach juice at 2.5bar.

[0043] The present invention will now be described in more detail in the following.

[0044] Detailed description of the invention

[0045] Definitions

[0046] Prior to discussing the present invention in further details, the following terms and conventions will first be defined:

[0047] Pore-forming agent

[0048] A "pore-forming agent" is a substance used to create pores within a material, often to enhance permeability or other properties. These agents are commonly used in the production of membranes, ceramics, and metallic porous materials. With respect to membrane technology, pore-forming agents are used to improve 84424PC01

[0049] 8 the permeability and selectivity of membranes for filtration and separation processes. In the present context, a pore-forming agent is an agent that is mixable but inert towards the monomer and / or oligomer and cross-linker used to generate the membrane.

[0050] In here, pore-forming agent and porogen are used interchangeably.

[0051] Initiator

[0052] In membrane production, an "initiator" is a substance used to start the polymerization process for forming the membrane material. For example, initiators help create active sites on monomers, leading to the formation of polymer chains and thereby producing the polymeric materials used in membranes

[0053] Initiators can be thermal initiatiors, photoinitiators, and / or redox initiators. In an embodiment, the initiator is a photoinitiator or a thermal initiator A photoinitiator may be a UV initiator

[0054] Monomer

[0055] In membrane production, a "monomer" is a small molecule that can chemically bind to other monomers to form a polymer; thus, monomers are the building blocks of polymers. During the polymerization process, monomers link together to form long chains or networks, creating the polymeric material used in membranes. The choice of monomer may affect the chemical, thermal, and mechanical properties of the resulting membrane. This includes factors such as permeability, selectivity, and resistance to fouling.

[0056] Oligomer

[0057] In membrane production, an "oligomer" is a molecule made up of a few monomer units, typically ranging from two to a few dozen. These oligomers can play a role in the formation and functionality of membranes. Oligomers can act as intermediates in the polymerization process, where they link together to form longer polymer chains. Oligomers can be used to control the pore size and distribution in membranes for filtration and separation.

[0058] The types of oligomers may include:

[0059] Linear oligomers, which have a straight-chain structure and can influence the mechanical properties of the membrane, or

[0060] Branched oligomers, which have a branched structure, which can affect the porosity and permeability of the membrane. 84424PC01

[0061] 9

[0062] The properties of oligomers, such as their molecular weight and structure, may impact the final properties of the membrane, including the membrane strength, flexibility, and filtration efficiency.

[0063] Cross-linker

[0064] A "cross-linker" is a chemical agent that forms covalent bonds between polymer chains, enhancing the mechanical and chemical stability of the membrane, thus cross-linkers create a network of interconnected polymer chains, which helps to improve the membrane's strength, durability, and resistance to solvents and temperature changes. Cross-linking can reduce the solubility of the polymer, increase its rigidity, and improve its thermal and chemical resistance. This makes the membrane more robust and suitable for various demanding applications.

[0065] Substrate

[0066] A "substrate" is the base material onto which the membrane is formed or deposited. The substrate provides mechanical support and stability to the membrane. It serves as the foundation for the selective layer that performs the actual filtration or separation. The choice of substrate may affect the overall performance of the membrane, including its permeability, selectivity, and resistance to fouling.

[0067] In an embodiment, the substrate is a fibrous substrate, preferably a non-woven fibrous substrate.

[0068] Fibrous substrate

[0069] A "fibrous substrate" is a base material composed of fibers, which provides structural support and enhances the functionality of various applications, including membrane production. Fibrous substrates are made from materials such as polymers (e.g., polyethersulfone, polyvinylidene fluoride), ceramics, or natural fibers. These fibers can be woven, nonwoven, or electrospun to create a porous structure.

[0070] The advantages of fibrous substrate include:

[0071] High Surface Area : The fibrous nature of the substrate provides a large surface area, beneficial for filtration and separation processes.

[0072] - Mechanical Strength: Fibrous substrates offer good mechanical properties, making the membranes durable and resistant to physical stress. 84424PC01

[0073] 10

[0074] Porosity and Permeability: The interconnected pores in fibrous substrates enhance the permeability and selectivity of the membrane.

[0075] In an embodiment, the fibrous substrate is selected from the group consisting of ceramic fibrous substrates, cellulose fibrous substrates, or polypropylene fibrous substrates

[0076] Non-woven fibrous substrate

[0077] A "non-woven fibrous substrate" is a type of material made from fibers that are bonded together without being woven or knitted. Non-woven substrates are composed of fibers that are randomly arranged and bonded together through mechanical, thermal, or chemical processes. Common non-woven fibrous substrates may include polymers such as polypropylene (PP), polyethylene (PE), and polyvinylidene fluoride (PVDF).

[0078] In an embodiment, the substrate is selected from the group consisting of polypropylene fiber, such as melt blown polypropylene fiber, polyethylene fiber, such as flashspun high density polyethylene fiber (HDPE), cellulose fiber, glass fiber, and ceramic fiber, such as ceramic wool or ceramic paper, preferably cellulose fiber, ceramic fiber, polypropylene fiber, or glass fiber, more preferably cellulose fiber, ceramic fiber or polypropylene fiber.

[0079] Glass fiber is similar to ceramic fiber, thus it is expected that glass fiber and ceramic fiber work similarly.

[0080] Polymerization

[0081] "Polymerization" is a chemical process in which small molecules, such as monomers, react to form long chains or three-dimensional networks known as polymers.

[0082] Fatty alcohol

[0083] A "fatty alcohol" is a type of high-molecular-weight, straight-chain primary alcohol derived from natural fats and oils or petrochemicals. Fatty alcohols typically have long carbon chains, ranging from 4 to 26 carbon atoms, such as C2-C12 fatty alcohol. They usually have an even number of carbon atoms and a single hydroxyl group (-OH) attached to the terminal carbon. Fatty alcohols can be saturated or unsaturated and may also have branched structures.

[0084] Fatty alcohols may be preferred as pore-forming agents due to their properties that enhance the structure and functionality of membranes. These include: 84424PC01

[0085] 11

[0086] Fatty alcohols can increase the viscosity of the polymer solution, which helps in creating a more stable and uniform membrane structure.

[0087] Fatty alcohols can contribute to the formation of a spongy membrane structure by preventing the formation of macrovoids. Thus, resulting in better pore interconnectivity.

[0088] - Fatty alcohols can speed up the liquid-liquid demixing process during the membrane formation, leading to larger and more consistent pore sizes.

[0089] Thus, fatty alcohols may be effective in producing membranes with high porosity and suitable pore size distribution for various applications.

[0090] Inhibitor

[0091] In membrane production, an "inhibitor" is a substance that slows down or prevents certain chemical reactions or processes. Inhibitors can be used to control the rate of polymerization, ensuring that the membrane forms with the desired properties. They help in managing the reaction kinetics to avoid defects and ensure uniformity.

[0092] The types of inhibitors may include:

[0093] Polymerization inhibitors: These are added to prevent premature polymerization of monomers during storage or processing.

[0094] Fouling inhibitors: Used to prevent the accumulation of unwanted materials on the membrane surface, which can degrade performance. These inhibitors can be chemical agents that modify the surface properties of the membrane.

[0095] Inhibitors work by interacting with reactive species or active sites in the polymerization process, thereby slowing down or halting the reaction. This control may assist in achieving the desired membrane characteristics.

[0096] Hydrophobic membrane

[0097] A "hydrophobic membrane" is a type of membrane that repels water. Hydrophobic membranes do not absorb water, making them ideal for applications where water resistance is desired. The hydrophobic nature of these membranes is due to their chemical composition and surface structure, which creates a barrier to water molecules. Hydrophobic membranes may be made from hydrophobic polymers such as polytetrafluoroethylene (PTFE), polypropylene (PP), and polyvinylidene fluoride (PVDF). 84424PC01

[0098] 12

[0099] Hydrophilic membrane

[0100] A "hydrophilic membrane" is a type of membrane that attracts and interacts with water. Hydrophilic membranes absorb water, which helps in maintaining a wet surface. This property may be beneficial for applications where water permeability is desired. The hydrophilic nature of these membranes is due to their chemical composition and surface structure, which allows them to form hydrogen bonds with water molecules. Hydrophilic membranes may be made from materials such as cellulose acetate, polyvinyl alcohol (PVA), and certain types of polyethersulfone (PES).

[0101] Symmetrical membrane

[0102] A "symmetrical membrane" is a type of membrane that has a uniform structure and composition throughout its thickness. Thus, symmetrical membranes have a consistent pore size and distribution across the entire membrane.

[0103] The consistent structure of the membrane ensures predictable and uniform performance across the membrane. Further, a symmetrical membrane is more resistant to mechanical stress than an asymmetrical membrane.

[0104] Asymmetrical membrane

[0105] An "asymmetrical membrane" is a type of membrane that has different structural and functional properties on each side. Asymmetrical membranes may comprise a thin, dense top layer (also known as the skin layer) and a thicker, porous support layer. The top layer is responsible for the selective separation, while the support layer provides mechanical strength.

[0106] Porous membrane

[0107] A "porous membrane" is a type of membrane that contains small holes or pores, allowing certain substances to pass through while blocking others. These membranes are used in various applications, including filtration, separation, and purification processes. The separation of solutes by porous membranes is based on the size of the molecules and the distribution of pore sizes.

[0108] Resin

[0109] In here, "resin" is to be understood as a mixture of monomer or oligomer and optionally a cross-linker. For example, a resin may comprise butyl-acrylate (monomer or oligomer) and trimethylolpropane triacrylate (cross-linker). 84424PC01

[0110] 13

[0111] LMH

[0112] LMH, or Liters (of permeate) per square meter (of membrane) per hour, is a unit of measurement used to describe the permeate flux in membrane processes. LMH measures the volume of permeate (filtered liquid) that passes through a membrane per unit area of the membrane per hour. It is a parameter in evaluating the performance of membrane systems. LMH is used in determining and comparing the performance of membranes.

[0113] Poly (glycol) or copolymer thereof

[0114] In the present context, the term "poly(glycol)" refers to a class of polymers derived from glycol monomers (organic compounds comprising two hydroxyl (- OH) groups). The term includes various types of polymers formed from different glycol units. The term "poly(glycol) or copolymer thereof" also encompass copolymers of poly(glycol), which is a polymer made from two or more different monomers, wherein at least one of them is a polymer derived from glycol monomers. The copolymers of poly(glycol) is preferably a polymer made from two or more different monomers of glycol.

[0115] Poly(glycol) or copolymer thereof includes, but is not limited to, polypropylene glycol, polyethylene glycol, poly(ethylene glycol-propylene glycol) copolymers, and polytetramethylene ether glycol.

[0116] Polyol or copolymer thereof

[0117] The term "polyol" refers to any molecule or polymer with two or more hydroxyl groups. The term includes poly(glycols) but is a broader term that may also encompass other hydroxyl-rich compounds. A copolymer of a polyol is a polymer made from two or more different monomers, wherein at least one of them is a polymer derived from polyol monomers. The copolymers of polyol is preferably a polymer made from two or more different monomers of polyol.

[0118] Organic solvent

[0119] The term "organic solvent" refers to any carbon-containing liquid capable of dissolving organic or polymeric materials, and may include alcohols, ketones, esters, ethers, hydrocarbons, and halogenated compounds. Organic solvents include, but is not limited to, acetone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, acetonitrile, tetra hydrofuran, and l-Methyl-2-pyrrolidone. C3-C20 fatty acid

[0120] The term "C3-C20 fatty acid" refers to a carboxylic acid with a carbon chain length ranging from 3 to 20 carbon atoms. The C3-C20 fatty acid may be saturated or 84424PC01

[0121] 14 unsaturated. C3-C20 fatty acid includes, but is not limited to, propionic acid, butyric acid, lauric acid, palmitic acid, oleic acid, and arachidic acid.

[0122] C3-C20 triglyceride

[0123] The term "C3-C20 triglyceride" refers to a molecule formed by three fatty acid chains esterified to a glycerol backbone, wherein each fatty acid chain contains between 3 and 20 carbon atoms. The C3-C20 triglyceride may be saturated or unsaturated.

[0124] The invention will now be described in further details in the following aspects and embodiments.

[0125] A method for producing a membrane

[0126] The method according to the present invention for producing a membrane comprising a substrate, a pore-forming agent, and at least one monomer and / or oligomer, provides a simple and cost-effective membrane production method, while ensuring robustness and adaptability of the membrane.

[0127] The inventors have demonstrated an improved permeability performance, mechanical stability, and thermal stability of the membrane produced by the method of the present invention compared to a commercial membrane. Further, it is proven that the method of producing a membrane of the present invention provides a membrane, which comprises adjustable properties and thereby allows optimization of the membrane design to meet specific operational requirements.

[0128] Thus, an aspect of the present invention relates to a method for producing a membrane comprising the steps of: a) providing at least one monomer and / or oligomer, b) optionally, mixing the at least one monomer and / or oligomer with a cross-linker, c) adding at least one pore-forming agent to the mixture comprising the monomer and / or oligomer, d) adding an initiator and at least one substrate, followed by e) activating the initiator.

[0129] As demonstrated in Examples 1 and 5, a membrane can successfully be produced by the above method. The presence of a cross-linker of step b) is optional, 84424PC01

[0130] 15 however the cross-linker may contribute to the hardness and thermal stability of the membrane. Further, the cross-linker increases processing time.

[0131] In an embodiment, the monomer or oligomer is a linear molecule comprising radical polymerizable functional groups, such as acryloyl, epoxides, and isocyanates. A monomer or oligomer is a molecule that can chemically bind to other monomers or oligomers to form a polymer. In particular, the method of the invention provides a porous polymer as seen in Examples 1 and 5. In principle, the monomer or oligomer may be any monomer or oligomer, which are polymerizable to form a polymer.

[0132] In an embodiment, the monomer and / or oligomer is selected from the group consisting of acrylates, methacrylates, epoxides, polyols, isocyanates, and siloxanes, or a mixture thereof. For example, in Examples 1 and 5, acrylate is used as a monomer.

[0133] In an embodiment, the monomer and / or oligomer is selected from the group consisting of Ci-Cs-alkyl-acrylate, Ci-Cs-alkyl-methacrylate, hydroxy(Ci-Cs-alkyl)- methacrylate, phenolic epoxy resin, Methyl Methacrylate, 2-, tert-butyl acrylate, Methoxy Polyethylene Glycol Acrylate, 2-ethylhexyl acrylate, Styrene, Glycidyl Methacrylate, Perfluorohexylethyl Acrylate, Perfluorodecyl Acrylate or a mixture thereof, preferably butyl-acrylate or (hydroxyethyl)methacrylate.

[0134] In Example 1, butyl-acrylate is used as a monomer. In Example 5, (hydroxyethyl)methacrylate is used as a monomer.

[0135] In an embodiment, the cross-linker is a molecule containing radical polymerizable functional groups, such as acryloyls, epoxides, and isocyanates.

[0136] In an embodiment, the cross-linker is selected from the group consisting of 1,6- Hexanediol diacrylate (HDDA), Trimethylolpropane triacrylate (TMPTA), Pentaerythritol triacrylate (PETA), Ethoxylated trimethylolpropane triacrylate (ETMPTA), Dipentaerythritol pentaacrylate (DPEPA), 1,4-Butanediol diacrylate (BDDA), Tripropylene glycol diacrylate (TPGDA), Bisphenol A ethoxylate diacrylate (BPAEDA), Polyethylene glycol diacrylate (PEGDA), Glycerol propoxylate triacrylate (GPTA), Bisphenol A diglycidyl ether (BADGE), Bisphenol F diglycidyl 84424PC01

[0137] 16 ether (BFDGE), 1,4-Butanediol diglycidyl ether (BDE), Cycloaliphatic diepoxide (e.g., 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate), preferably trimethylolpropane triacrylate. In Examples 1 and 5, trimethylolpropane triacrylate is used as a cross-linker.

[0138] In an embodiment, the pore-forming agent is selected from the group consisting of a C2-C12 alcohol, polyol, such as poly(glycol), or copolymer thereof, organic solvent, C3-C20 fatty acid, and C3-C20 triglyceride, preferably C2-C12 alcohol or poly(glycol). In an embodiment, the pore-forming agent is a C2-C12 alcohol. In an embodiment, the polyol or copolymer thereof, such as poly(glycol) or copolymer thereof, has a molecular weight selected from the range of 200 g / mol to 8000 g / mol, such as 200 g / mol to 6000 g / mol, such as 200 g / mol to 2000 g / mol, preferably 200 g / mol to 1000 g / mol, such as 200 g / mol to 800 g / mol, most preferably 400 g / mol. In another embodiment, the polyol or copolymer thereof, such as the poly(glycol) or copolymer thereof, is selected from the group consisting of polypropylene glycol, polyethylene glycol, poly(ethylene glycolpropylene glycol) copolymers, and polytetramethylene ether glycol, preferably polypropylene glycol.

[0139] In an embodiment, the organic solvent is selected from the group consisting of acetone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, acetonitrile, tetra hydrofuran, and l-Methyl-2-pyrrolidone.

[0140] In an embodiment, the C3-C20 fatty acid or C3-C20 triglyceride is saturated or unsaturated. In another embodiment, the C3-C20 fatty acid is selected from the group consisting of C3-C16 fatty acid, such as C4-C14 fatty acid, such as C6-C12 fatty acid, such as Cs-Cio fatty acid. In yet another embodiment, the C3-C20 triglyceride is selected from the group consisting of C3-C16 triglyceride, such as C4- C14 triglyceride, such as C6-C12 triglyceride, such as Cs-Cio triglyceride. Preliminary data indicate that sunflower oil could be used as the pore-forming agent. Thus, in an embodiment, the C3-C20 triglyceride is sunflower oil.

[0141] The pore-forming agent creates pores within a material, which enhances properties of the membrane, such as improved permeability and selectivity of membranes for filtration and separation processes. In principle, the pore-forming agent can be any type of pore-forming agent. In Example 3, it is shown that the structure of the membrane material is influenced by the resin to pore-forming agent ratio, which is indicated by changes in pore size and porosity. Thus, the 84424PC01

[0142] 17 performance of the membranes can be adjusted by altering the resin to poreforming agent ratio. This adaptability enhances the potential for these membranes to be applied in diverse separation processes.

[0143] In an embodiment, the C2-C12 alcohol is a C2-C12 primary alcohol, a C2-C12 secondary alcohol, or a C2-C12 tertiary alcohol, preferably a C2-C12 primary alcohol. As seen in Examples 1 and 5, a C2-C12 primary alcohol (1-decanol) is used as a pore-forming agent.

[0144] In an embodiment, the C2-C12 alcohol is a C2-C12 fatty alcohol.

[0145] Fatty alcohols contribute to a more stable and uniform membrane structure, better pore interconnectivity, and more consistent pore sizes. As seen in Examples 1 and 5, a C2-C12 fatty alcohol (1-decanol) is used as a pore-forming agent.

[0146] In a further embodiment, the C2-C12 alcohol comprises at least one double bond and / or at least one triple bond, preferably at least one double bond.

[0147] In an embodiment, the C2-C12 alcohol is an alkanol. As seen in Examples 1 and 5, an alkanol (1-decanol) is used as a pore-forming agent.

[0148] In an embodiment, the C2-C12 alcohol is selected from the group consisting of propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, propylene glycol, butanediol, 1,2,3-propanetriol (Glycerin), erythritol, and xylitol, preferably decan-l-ol. As seen in Examples 1 and 5, 1- decanol or decan-l-ol is used as a pore-forming agent.

[0149] In an embodiment, the pore-forming agent is selected from the group consisting of propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, propylene glycol, butanediol, 1,2,3-propanetriol (Glycerin), erythritol, xylitol, polypropylene glycol, polyethylene glycol, poly(ethylene glycolpropylene glycol) copolymers, polytetramethylene ether glycol, acetone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, acetonitrile, tetra hydrofuran, and l-Methyl-2-pyrrolidone, or a mixture thereof, preferably polypropylene glycol or decan-l-ol. As seen in Examples 1 and 5, 1-decanol or decan-l-ol is used as a pore-forming agent. Nonreactive polymers, such as polypropylene glycol, can also be used as pore-forming agents as demonstrated in Example 7 and 8. 84424PC01

[0150] 18

[0151] In an embodiment, the ratio between the mixture of step b) and the pore-forming agent is in the range of 20:80 to 80:20 (w / w), such as 30:70 to 70:30 (w / w), such as 35:65 to 65:35 (w / w), such as preferably 40:60 to 60:40 (w / w).

[0152] As seen in Example 3, the structure of the membrane materials is influenced by the ratio of resin, comprising monomer and cross-linker, to pore-forming agent in terms of pore size and porosity. In particular, the membrane's flux performance is affected by resin to pore-forming agent ratio.

[0153] In an embodiment, the substrate is a fibrous substrate, preferably a non-woven fibrous substrate. The fibrous substrate provides the strength and the final structure of the membrane. As seen in Example 2, a substrate, such as a fibrous substrate is effective for enhancing the mechanical integrity of the membrane. Further, in Example 4 various non-woven fibrous substrates are used to produce membranes. As shown in Example 7, the membrane can also comprise more than one substrate. Thus, in an embodiment, the membrane comprises two substrates.

[0154] In a further embodiment, the substrate is selected from the group consisting of polypropylene fiber, such as melt blown polypropylene fiber, polyethylene fiber, such as flashspun high density polyethylene fiber (HDPE), cellulose fiber, glass fiber, and ceramic fiber, such as ceramic wool or ceramic paper, preferably cellulose fiber, ceramic fiber, polypropylene fiber, or glass fiber, more preferably cellulose fiber, ceramic fiber or polypropylene fiber. As shown in Example 4, cellulose, polypropylene, or ceramic fibers were used as a substrate for producing membranes. Example 4 demonstrates that a variety of fibrous substrates, such as cellulose, polypropylene, ceramic fibers, are suitable for the fabrication of membranes using the method of the present invention

[0155] In an embodiment, the initiator is a photoinitiator or a thermal initiator. The initiator starts the polymerization process for forming the membrane material. In principle, the initiator may be any initiator, which causes formation of polymer chains.

[0156] In a preferred embodiment, the initiator is a photoinitiator, preferably a UV initiator. As seen in the examples, a UV initiator is used for membrane production. 84424PC01

[0157] 19

[0158] In an embodiment, the photoinitiator is selected from the group consisting of Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide (Irgacure 819), 2-Hydroxy-2- methyl-l-phenyl-propan-l-one (Darocur 1173), 2,2-Dimethoxy-l,2- diphenylethan-l-one (Irgacure 651), 2,2-Dimethoxy-2-phenylacetophenone (DMPA), Benzoin Benzyl Ether (BBE), Benzophenone (BP), 2-Benzyl-2- dimethylamino-l-(4-morpholinophenyl)-butanone-l (Irgacure 369), l-[4-(2- Hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-l-propane- 1-one (Irgacure 2959), Bis(.eta.5-2,4-cylcopentadien-l-yl)-bis(2,6-difluoro-3-(lH-pyrrol-l-yl)phenyl) titanium (Irgacure 784), Bis (2,6-dimethoxybenzoyl)-2,4,4- Trimethylpentylphosphinoxide and 2-Hydroxy-2-Methyl-l-Phenylpropanone (Irgacure 1700), and (4-methylphenyl) [4-(2-methylpropyl)phenyl] iodonium hexafluorophosphate (Irgacure 250), preferably Bis(2,4,6-trimethylbenzoyl)- phenylphosphineoxide (Irgacure 819).

[0159] In the examples, Irgacure 819 is used as a photoinitiator.

[0160] In an embodiment, the thermal initiator is selected from the group consisting of Benzoyl Peroxide (BPO), Di-tert-butyl Peroxide (DTBP), Di(2-ethylhexyl) Peroxydicarbonate (DEHPC), Lauroyl Peroxide, Dibenzoyl Peroxide (DBP), Cyclohexanone Peroxide (CHP), Cumyl Peroxyneodecanoate (CPND), Tert-Butyl Peroxybenzoate (TBPB), and Azobisisobutyronitrile (AIBN), or a mixture thereof.

[0161] In an embodiment, the substrate is saturated with the mixture of step c) and the initiator. The saturation of the substrate with the mixture of step c), comprising monomer or oligomer, a pore-forming agent, and optionally a cross-linker, ensures interpenetration of the agents into the substrate to create a uniform membrane material. The porous nature is achieved via a polymerization-induced phase separation process between the polymers and the pore forming agent, and the substrate provides the strength and the final structure of the membrane.

[0162] In an embodiment, the activation of the initiator is conducted by irradiation, such as irradiation with UV light, or heat treatment. In the examples, UV irradiation has been used to activate the initiator. The activation of the initiator may depend on the initiator used. 84424PC01

[0163] 20

[0164] In an embodiment, step d) further comprises adding an inhibitor.

[0165] In an embodiment, the inhibitor is selected from the group consisting of Hydroquinone monomethyl ether (MEHQ), Phenothiazine, BHT (Butylated Hydroxytoluene), Copper(I) chloride (CuCI), N,N-Diethylaniline (DEA), and Diphenylamine, or a mixture thereof.

[0166] In an embodiment, the heat treatment is conducted at a temperature in the range of 50 °C to 130 °C, such as 60 °C to 120 °C, such as 70 °C to 100 °C.

[0167] In an embodiment, the irradiation with UV is performed using light having a wavelength of 250nm to 500nm for at least 0.1 seconds, such as in the range of 0.1 seconds to 800 seconds, such as 150 seconds, such as 200 seconds, preferably at least 200 seconds.

[0168] UV irradiation may be performed for at least 2 seconds and up to including 5 minutes in each side of the membrane. UV irradiation for 10 minutes is considered to be the upper limit. The wavelength for irradiation is preferably the wavelength for UV LED light or halogen light. As seen in Examples 1 and 5, UV irradiation is performed for 200 seconds on each side of the membrane. Preferably, the UV irradiation is performed at room temperature at 20°C to 25°C. However, increasing or decreasing the temperature may be desired for the membrane depending on the resin.

[0169] In an embodiment, the method further comprises a step of washing the membrane.

[0170] In a further embodiment, the membrane is washed with toluene, hexane, propanol, water, and / or acetone. In principle, the membrane may be washed in any washing media. In Example 1, acetone is used to wash the membrane.

[0171] After washing the membrane, the membrane may be wet and / or comprise residue of the agents used for producing the membrane, which can be removed by drying the membrane. Thus, in an embodiment, the method further comprises a step of drying the membrane. 84424PC01

[0172] 21

[0173] In an embodiment, the membrane is dried by heating it to at least 60°C, such as at least 70°C, such as at least 80°C, such as at least 90°C, such as in the range of 100°C to 340°C, such as 110°C, such as 120°C, such as 230°C, such as 340°C, preferably 120°C for a period in the range of 10 hours to 30 hours, preferably 24 hours. The purpose of drying the membrane is to remove any liquid residue from the production of the membrane. In order to remove any unwanted residue from the membrane, the membrane is dried at a temperature equal to the boiling point of the unwanted residue, or the membrane can be exposed to a high temperature, such as 120°C, for a prolonged period to ensure evaporation of the unwanted residue. For example, the pore-forming agent, 1-decanol, has a boiling point of 230°C, thus the drying temperature may be 230°C to remove residues of 1- decanol. However, a temperature of 230°C may be damaging to the membrane, hence the membrane may be exposed to a temperature of 120°C for a longer period of time. The drying temperature depends on the residue, such as the poreforming agent, to be removed from the membrane.

[0174] In an embodiment, the membrane is dried until odour-free.

[0175] A membrane obtained by the method

[0176] A further aspect of the invention related to a membrane obtained by or obtainable by the method according to the invention.

[0177] A membrane comprising a substrate coated with a porous polymer Another aspect of the invention related to a membrane comprising a substrate coated with a porous polymer composed of cross- 1 inked monomers and / or crosslinked oligomers having radical polymerizable functional groups, such as acryloyls, epoxides, and isocyanates. As seen in the examples, a membrane comprising the above features are successfully obtained. Further, the membrane of the invention comprises improved mechanical properties, flexibility for adjusting properties for optimizing membrane design to meet specific operational requirements, improved permeability performance, and a higher thermal stability.

[0178] In an embodiment, the membrane is a hydrophobic or hydrophilic membrane. 84424PC01

[0179] 22

[0180] As seen in Example 1, a hydrophobic membrane is produced. In Example 5, a hydrophilic membrane is produced. Thus, the examples demonstrate the ability to adjust between hydrophobicity and hydrophilicity.

[0181] In an embodiment, the membrane is a hydrophobic membrane. As seen in Example 1, a hydrophobic membrane is produced.

[0182] In an embodiment, the substrate is a fibrous substrate, preferably a non-woven fibrous substrate. The fibrous substrate provides the strength and the final structure of the membrane. As seen in Example 2, a substrate, such as a fibrous substrate is effective for enhancing the mechanical integrity of the membrane. Further, in Example 4 various non-woven fibrous substrates are used to produce membranes.

[0183] In an embodiment, the membrane is symmetrical or asymmetrical, preferably symmetrical. In the examples, a symmetrical membrane is produced. The porous polymer is generated within the fibrous substrate and the resulting membrane is therefore symmetrical. A symmetrical membrane is more resistant to mechanical stress than asymmetrical membranes.

[0184] In an embodiment, the membrane is porous. As seen in the Example 3, the porosity of the membrane enhances the membrane performance, such as improved permeability and selectivity. Further, the desired properties of the final membrane may adjusted in terms of porosity. A porous membrane can offer high permeability and a large surface area, while also facilitating additional functionality.

[0185] Use of the membrane

[0186] An aspect of the invention related to use of the membrane according to the invention for electrochemical membrane processes, such as electrodialysis, electro filtration or electro osmosis, for concentration gradient, such as dialysis, gas separation or pervaporation, for thermal gradient, such as membrane distillation, membrane assisted crystallization or thermally assisted reverse osmosis, for pressure gradient, such as reverse osmosis, nanofiltration, ultrafiltration, microfiltration, oil water separation, or dairy separation. 84424PC01

[0187] 23

[0188] Alternative aspects

[0189] An alternative aspect of the present invention relates to a method for producing a membrane comprising the steps of: a) providing at least one monomer and / or oligomer, b) optionally, mixing the at least one monomer and / or oligomer with a cross-linker, c) adding a pore-forming agent to the mixture comprising the monomer and / or oligomer, d) adding an initiator and a substrate, followed by e) activating the initiator.

[0190] Another alternative aspect of the present invention relates to a method for producing a membrane comprising the steps of: a) providing at least one monomer and / or oligomer, b) mixing the monomer and / or oligomer with an initiator, b) optionally, mixing the at least one monomer and / or oligomer and initiator with a cross-linker, c) adding at least one pore-forming agent to the mixture comprising the monomer and / or oligomer and initiator, d) adding at least one substrate, followed by e) activating the initiator.

[0191] An alternative aspect of the present invention relates to a method for producing a membrane comprising the steps of: a) mixing at least one monomer with a cross-linker, b) adding at least one pore-forming agent to the mixture, c) adding a UV initiator to the mixture of step b), d) soaking at least one fibrous substrate, such as a fibrous substrate, in the mixture of step c), followed by d) irradiating the UV initiator with UV light.

[0192] In an embodiment, the fibrous substrate is saturated with the mixture of step c). 84424PC01

[0193] 24

[0194] It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

[0195] All patent and non-patent references cited in the present application, are hereby incorporated by reference in their entirety.

[0196] The invention will now be described in further details in the following non-limiting examples.

[0197] Examples

[0198] Example 1 - Materials and methods

[0199] In the present invention, a membrane is produced by mixing a monomer, a crosslinker, a pore-forming agent, a UV initiator and a fibrous substrate and subsequently irradiating the UV initiator with UV light. The first four components generate a porous polymer when irradiated with UV light, but since the fibrous substrate is submerged in said solution, the porous polymer is generated within the fibrous substrate and the resulting membrane is therefore symmetrical. However, symmetry of the membrane is obtained if the polymerization occurs uniformly. An asymmetric membrane may be achieved by ensuring uneven polymerization such as if the substrate is only partially wetted or UV does not travel through the substrate, but only exposing the top of the substrate.

[0200] The following is a detailed description of one way of producing a membrane according to the present invention.

[0201] Butyl-acrylate (CAS 141-32-2) was used as the monomer, whereas trimethylolpropane triacrylate (CAS 15625-89-5) was used as the cross-linker. The pore-forming agent was 1-decanol (CAS 112-30-1), and irgacure 819 was used as the UV initiator. The fibrous substrate used in step c) was a nonwoven fiber mat, such as cellulose, ceramic fibers, or polypropylene.

[0202] Method for producing a hydrophobic membrane of the present invention:

[0203] 1. Mix 60 wt% of butyl-acrylate and 40 wt% of trimethylolpropane triacrylate to obtain mixture A

[0204] 2. Mix mixture A and 1-decanol (40 wt% and 60wt%, respectively) to obtain mixture B.

[0205] 3. Add 5wt% irgacure 819 of the total mass of mixture B to obtain mixture C. 84424PC01

[0206] 25

[0207] 4. Soak the fibrous substrate in mixture C until completely saturated.

[0208] 5. UV irradiates each side of the membrane for 200s.

[0209] 6. Wash membrane pieces in acetone for 24h.

[0210] 7. Put in oven at 120°C for 24h (or until odder-free / hydrophobic).

[0211] In Figure 1, cellulose fibrous substrate has been employed as the fibrous substrate to demonstrate the membrane fabrication process of the present invention. As shown in Figure 1A, a thin, self-supporting membrane has been produced. The surface hydrophobicity, measured by contact angle, is depicted in Figure IB. It is evident that the contact angle of the membrane surface exceeds 140°, confirming that a hydrophobic surface has been achieved. The hydrophobicity of the membrane is crucial for its application in membrane distillation. The hydrophobic membranes have potential applications across a broad range of fields, including filtration, wastewater treatment, oil-water separation, Power-to-X, resource recovery, and industries such as pharmaceuticals, food and beverage, and chemical processing. Additional parameters of the membrane, such as thickness, pore size, and porosity are discussed in detail in the subsequent examples.

[0212] Example 2 - The fibrous substrate is effective to resist physical stress

[0213] Aim of study

[0214] In this study, the inventors conducted stress-strain tests to evaluate and compare the mechanical strength and structural integrity of membranes, both with and without the reinforcement of the fibrous substrate. The aim of this testing was to highlight the necessity and effectiveness of the incorporation of the fibrous substrate in enhancing the durability and resilience of the membranes under various loading conditions. By assessing the response of each membrane to applied stress and identifying the points at which they yield or break, materials for membrane synthesis can be designed and selected to tailor the membrane specifically for applications that demand high-performance characteristics. Materials and methods

[0215] In this study, both membranes with and without the fibrous substrate were subjected to stress-strain tests to assess their mechanical properties. The membranes were tested in a controlled laboratory setting using a Low force Instron universal testing machine 6800 series from Instron. The fabrication process for producing the membranes were detailed in Example 1. The type of reinforcement used in this study was cellulose fiber substrate. For each test, 84424PC01

[0216] 26 samples were loaded at a constant strain with stress and strain being recorded until rupture to compare the performance characteristics of the membranes with and without the fibrous substrate.

[0217] Results

[0218] It is evident that membrane materials lacking the fibrous support exhibit low mechanical strength. Specifically, as shown in Figure 2, the unsupported membrane material ruptured at stress levels below 1 MPa and strain levels below 1%. Furthermore, the material appeared brittle and inflexible, indicating that it is unsuitable for real-life applications. Conversely, with the inclusion of the fibrous support, the mechanical strength of the membranes significantly improved. These reinforced membranes could withstand a stress load of up to about 5.5 MPa before rupturing, and the strain can extend to about 11%. Additionally, said membranes were more flexible and easier to handle compared with the membranes without the fibrous substrate. The mechanical properties of the membranes largely depend on the mechanical characteristics of the fibrous substrate.

[0219] Conclusion

[0220] This example demonstrates that fibrous substrate is effective for enhancing the mechanical integrity of the membrane. Without the fibrous substrate, the membrane would not be able to withstand the demands of handling and operational conditions.

[0221] Example 3 - Optimizing the ratio of the resin to the pore-forming agent

[0222] Aim of study

[0223] The aim of this study was to demonstrate the effects of varying the ratio between the resin and the porogen on the properties of the membrane. Specifically, the research focused on how changes in the ratio influenced the mechanical strength, pore size, and overall performance of the membrane in distillation processes. By investigating these variables, the study optimized the membrane's functionality through modifications in its composition. This study also highlighted the potential applications of the current invention across a broad spectrum of separation technologies.

[0224] Materials and methods

[0225] The membrane synthesis was performed as described in Example 1 using cellulose as the fibrous substrate. Mixture A of step 1 comprising 60 wt% of Butyl-acrylate and 40 wt% trimethylolpropane triacrylate constitutes the resin. In step 2, the resin and 1-Decanol were combined in ratios of 35 wt% / 65 wt% (Ml membrane), 84424PC01

[0226] 27

[0227] 40 wt% / 60 wt% (M2 membrane), and 45 wt% / 55 wt% (M3 membrane), respectively, to produce mixture B.

[0228] In this study, membranes with varying resin to porogen ratios were subjected to stress-strain tests to evaluate their mechanical properties. These tests were conducted in a laboratory setting using a Low force Instron universal testing machine 6800 series from Instron. For each test, samples were loaded at a constant strain rate and monitored for stress and strain until rupture to facilitate comparison. Additionally, structural characterization of the membrane material, including thickness, pore size, and porosity, was determined using capillary flow porometry, Porolux 1000 from Porometer. The desalination performance of the membranes was also assessed using a laboratory direct contact membrane distillation system with a Grant brand heater for heating the feed input, an Masterflex L / S peristaltic pump ensuring a steady liquid flow on the feed and permeate, and a Julabo 200F cooler ensuring a chilled permeate at various operating temperatures.

[0229] Results

[0230] The mechanical strength of membranes with varying resin to porogen ratios are illustrated in Figure 3. The resin level ranged from 35% to 45%, and the tests were repeated 2 to 3 times to minimize deviation. The results indicate that the different resin to porogen ratios have little impact on the mechanical properties of the membranes, as all tested membranes displayed similar stress-strain curves. Specifically, the average rupture stress levels for membranes with resin to porogen ratios of 35 wt% / 65 wt%, 40 wt% / 60 wt%, and 45 wt% / 55 wt% were 5.10 MPa, 5.14 MPa, and 4.87 MPa, respectively, while the strains were approximately 7.87, 9.63, and 9.66, respectively.

[0231] On the other hand, the resin to porogen ratio significantly impacted the structure of the membranes. Figure 4 presents results from capillary flow porometry. Figure 4A reveals that the membrane thickness ranges between 200 pm and 260 pm, the range of the membrane thickness can be further expanded with the maximum thickness achieved being 2 mm. Additionally, the porosity of the membrane decreases with an increase in the resin to porogen ratio (Figure 4B). The cellulose fiber substrate exhibits a porosity above 85%. When the resin to porogen ratio is increased from 35 wt% / 65 wt% to 45 wt% / 55 wt%, the porosity declines from approximately 78% to about 68%. This reduction in porosity is 84424PC01

[0232] 28 anticipated, as a lower resin to porogen ratio leads to denser membrane materials.

[0233] Figure 4C shows triple determination capillary flow porometry using Porofill as a wetting agent for the Ml, M2, and M3 membranes. The gas flow through the membrane pores increases due to the increase of the pressure and de-wetting of the pores.

[0234] Figure 4D shows the corresponding pore size diameters derived from Figure 4C. The membrane pore size distribution is characterized by the gas flow percentage increase at a specified applied pressure.

[0235] The membranes also display a uniform pore size distribution, as depicted in Figure 4E. The difference between the maximum and the mean pore sizes across membranes with various resin to porogen ratios remain within 100 nm. Similar to porosity, the pore size follows the same trend: As the resin to porogen ratio increases, the mean pore size decreases, dropping from about 800 nm to 500 nm. This pattern indicates that the pore size of the membranes can be finely adjusted by altering the resin to porogen ratio, thus broadening the potential applications of this invention in various separation processes.

[0236] The performance of the produced membrane was evaluated using a Direct Contact Membrane Distillation (DCMD) setup. For the evaluation, a feed solution containing 32g / L of NaCI was used. The heater for the feed solution operated within a temperature range of 50°C to 80°C, while the permeate side was cooled to 15°C. As depicted in Figure 5, the flux of all membranes tested increased with rising temperature. Additionally, the flux also increased as the resin to porogen ratio decreased. Between 50°C and 80°C, the average flux of the membrane rose from 5.4-17.8 LMH to 7.44-26.7 LMH for Ml to M3 (Figure 5A, C, E), respectively. The enhancement of flux with a decrease in the resin to porogen ratio can be attributed to the increase in porosity and pore size. This suggests that the performance of the membranes can be tuned by altering the resin to porogen ratio. Furthermore, the membrane demonstrated high stability, maintaining a consistent flux throughout the testing period. The membrane also exhibited excellent desalination capabilities; the conductivity was significantly reduced to below 2 pS / cm (Figure 5B, D, F) for all tested membranes after the distillation process, indicating that nearly 100% of the salt ions were removed. Conclusion 84424PC01

[0237] 29

[0238] In conclusion, this study has provided insights into the performance and structural properties of the invented membranes in response to variations in the ratio of the resin to the pore-forming agent. The findings reveal that the resin to porogen ratio has a minimal impact on the membrane's mechanical strength, which displays consistent stress-strain behavior across different ratios. In contrast, the structure of the membrane materials is significantly influenced by the resin to porogen, as indicated by changes in pore size and porosity. Specifically, when the resin to porogen is increased from 35 wt% / 65 wt% to 45 wt% / 55 wt%, porosity declines from approximately 78% to about 68%. Concurrently, the mean pore size decreases from about 800 nm to 500 nm.

[0239] The DCMD setup confirmed that the membrane's flux performance improves with increased temperature and decreased resin to porogen ratio. Between 50°C and 80°C, the average flux of the membrane rose from 5.4-17.8 LMH to 7.44-26.7 LMH for Ml to M3, respectively, demonstrating the tunability of the membrane's performance through controlled parameter adjustments. Additionally, the membrane exhibited high stability and superior desalination capabilities, effectively reducing the conductivity of the feed solution, and achieving nearcomplete salt removal.

[0240] Overall, the findings underscore the membrane's adjustable properties. The ability to fine-tune the membrane's characteristics through the resin to porogen ratio presents a promising approach for optimizing membrane design to meet specific operational requirements. This adaptability enhances the potential for these membranes to be applied in diverse separation processes. Hydrophobicity and hydrophilicity will change the adhesion of fouling agents and therefore gives the possibility to tune any pressure driven process, it increases the chemical and thermal stability making the membrane useful in high temperature applications. For membrane distillation purposes both high thermal stability and hydrophobicity are preferred including as porous membrane as possible. Otherwise, all parameters will be preferable depending on the application.

[0241] Example 4 - Testing different fibrous substrates

[0242] Aim of study

[0243] The aim of this study was to explore the feasibility of fabricating membranes using a variety of fibrous materials. By examining different types of fibers, the study seeks to broaden the potential for creating membranes with diverse material compositions. This research focused on characterizing and assessing the 84424PC01

[0244] 30 performance of each reinforcement type when integrated with membrane technology, to enhance the practical applications of these membranes in various industrial settings.

[0245] Materials and methods

[0246] In this study, ceramic, cellulose and polypropylene fibrous substrates were selected for the fabrication of the membranes. The detailed membrane synthesis method was described in Example 1. The desalination performance of membranes generated using ceramic, cellulose and polypropylene fibrous substrates were evaluated using a laboratory membrane distillation system with a Grant brand heater for heating the feed input, an Masterflex L / S peristaltic pump ensuring a steady liquid flow on the feed and permeate, and a Julabo 200F cooler ensuring a chilled permeate. Additionally, the surface hydrophobicity and pore size of the membranes based on the ceramic and cellulose fibrous materials were determined through contact angle measurement and capillary flow porometry with Biotic Scientific Attention Theta Lite optical tensiometer and Porolux 1000, respectively. Results

[0247] For the membrane distillation experiment, a feed solution containing 50 g / L of NaCI was utilized. The feed solution's heater operated within a temperature range of 50°C to 90°C, while the permeate side was cooled to 15°C. Figure 6 illustrate the flux and permeate conductivity of the membrane derived from ceramic fiber under varying operating temperatures. It is observed that the membrane's flux increases with the rise in operating temperature, escalating from about 3 LMH to 11 LMH as the feed temperature increased from 50°C to 90°C (Figure 6A). Additionally, the membrane demonstrated high stability, maintaining a constant flux throughout the testing period. Moreover, the membrane exhibited excellent desalination capabilities; the feed solution initially had a conductivity of about 66000 pS / cm, which was significantly reduced to about 2 pS / cm after the membrane distillation process, indicating that nearly 100% of the salt ions were removed (Figure 6B).

[0248] A similar result can be observed with the membranes derived from non-woven polypropylene fiber. Figure 7 illustrates the performance of the membrane in an MD process. The process involved 50g / L of NaCI feed solution with the heater operating at 70°C, while the permeate side was cooled to 15°C. The membrane maintained a stable flux of approximately 7 LMH throughout the testing period (Figure 7A). Additionally, the membrane demonstrated high desalination 84424PC01

[0249] 31 capability; the feed solution initially had a conductivity of about 66000 pS / cm, and the permeate exhibited a conductivity of only below 10 pS / cm following the membrane distillation process (Figure 7B). The abrupt increase in conductivity at around 150 min may be due to a deviation caused by the conductivity meter. On the other hand, the surface properties of the membranes have been evaluated. The contact angle, which is indicative of surface hydrophobicity, was measured based on ceramic, cellulose, and polypropylene fiber substrates, and the results are displayed in Figure 8. It is evident that the contact angle for both of the membrane surfaces derived from either ceramic fiber (Figure 8A) or cellulose fiber (Figure 8B) exceeded 140°, and for the membrane surface derived from polypropylene fiber (Figure 8C) around 139°, indicating that hydrophobic surfaces were achieved using the method of the present invention. The hydrophobicity of the membranes are beneficial for processes such as membrane distillation, oil-water separation, and similar applications.

[0250] Furthermore, the pore size of the membranes, based on cellulose and ceramic fibers, were evaluated using capillary flow porometry. The findings are presented in Figure 9. The analysis reveals that the mean pore size of the membrane based on cellulose fibers was approximately 650 nm, occurring when the percent flow reaches about 50%, and the maximum pore size was within 700 nm. Conversely, the membranes incorporating ceramic fiber substrate exhibit smaller pores, with a mean pore size of about 55.84 nm and a maximum pore size around 182.7 nm. These results demonstrate that the current invention can achieve uniformly sized pores across membranes made from various fibrous substrates.

[0251] Conclusion

[0252] This study conclusively demonstrates that a variety of fibrous substrates, such as cellulose, polypropylene, ceramic fibers, etc., were suitable for the fabrication of membranes using the method of the present invention. The innovative process developed herein enables the production of membranes with a highly hydrophobic surface, characterized by a surface contact angle of approximately 140 degrees. These membranes feature a consistent pore size, ranging from 50 nm to 1000 nm— a range that can be further adjusted to meet specific requirements. Furthermore, membranes constructed from different materials consistently exhibited a stable flux, maintaining values between 3 LMH and 11 LMH. The membranes also demonstrate exceptional performance in membrane distillation applications, achieving nearly 100% salt rejection. 84424PC01

[0253] 32

[0254] Example 5 - Generating hydrophilic membranes

[0255] Aim of study

[0256] The pervious examples demonstrate that the developed method can produce hydrophobic membranes. This study aimed at highlighting the versatility of this invention be demonstrating that the invention was also capable of generating hydrophilic membranes. Hydrophilic membranes are crucial in scenarios requiring efficient water permeation, such as water treatment and pressure-driven membrane filtration. The dual functionality of this method emphasizes the technology's adaptability across a range of industrial applications. The capacity of this invention to adjust surface hydrophobicity enhances its utility in various sectors.

[0257] Materials and methods

[0258] Like Example 1, the hydrophilic porous polymer consists of the monomer, the crosslinker, a UV initiator, and the pore-forming agent (C4-C12 alcohol). By combining the porous polymer with a fibrous substrate, a membrane can be derived. The following is a detailed description of one way of generating hydrophilic membranes using the membrane fabrication method of the present invention.

[0259] (hydroxyethyl)methacrylate (CAS 868-77-9) was used as the monomer, whereas trimethylolpropane triacrylate (CAS 15625-89-5) was used as the cross-linker.

[0260] The UV initiator was irgacure 819, and 1-Decanol (CAS 112-30-1) was used as the pore-forming agent. The fibrous substrate used in this example was cellulose filter paper.

[0261] Method for producing a hydrophilic membrane of the present invention:

[0262] 1. Mix 80 wt% of (hydroxyethyl)methacrylate and 20 wt% of trimethylolpropane triacrylate to obtain mixture A

[0263] 2. Add 5wt% irgacure 819 of the total mass of mixture A to obtain mixture B.

[0264] 3. Mix mixture B and 1-Decanol (40 wt% / 60wt% and 60 wt% / 40wt%, respectively) to obtain mixture C.

[0265] 4. Soak cellulose substrate in mixture C for 5 min until completely saturated.

[0266] 5. UV irradiate each side of the membrane for 200 s.

[0267] Results

[0268] This study demonstrated the hydrophilicity and water flux characteristics of the invention as a promising pressure-driven membrane technology. Figure 10 illustrates the contact angle of the obtained membrane surface, showing a contact 84424PC01

[0269] 33 angle of approximately 76°. This confirms the achievement of a hydrophilic surface, in contrast to the membrane surface on the membranes obtained in Example 4. These results indicate that the invented method can effectively modulate between hydrophobicity and hydrophilicity.

[0270] The membranes, differentiated by two resin to porogen ratios of 40 wt% / 60 wt% and 60 wt% / 40 wt%, respectively, were tested in a dead-end filtration system to measure water flux under an operational pressure of 1 bar. As depicted in Figure 11, the membrane with a 40 wt% / 60 wt% resin to porogen ratio exhibited a significantly higher water flux, approximately 367.7 LMH bar1, compared to the 60 wt% / 40 wt% resin to porogen ratio, which had about 28.2 LMH bar1. This enhanced performance is likely due to increased porosity and pore size, a result of the higher porogen concentration as demonstrated in Example 3.

[0271] Conclusion

[0272] In conclusion, this study validates the effectiveness of the developed membrane fabrication method in achieving desired hydrophilic properties and enhancing water flux. Adjusting the resin to porogen ratios within the membrane composition has proven effective in influencing performance characteristics under pressure- driven conditions. Specifically, higher porogen concentrations significantly boost water flux. The method not only demonstrated the ability to fine-tune between hydrophobicity and hydrophilicity but also underscores the potential to broaden its application across various separation processes.

[0273] Example 6 - Comparing the membrane of the present invention with a commercial membrane

[0274] Aim of study

[0275] The aim of this study was to conduct a comparative study between the membrane of the present invention and a commercial membrane.

[0276] Materials and methods

[0277] The membrane of the present invention was obtained according to Example 1. Results

[0278] The commercial membrane (MICRODYN - MD 020 CP 2N) and its properties are described in Shirazi et al. (Membrane crystallization for recovery of lithium carbonate crystals: Study on process parameters and salts effect for Li COs-NaCI- KCI-LiCI solutions, Desalination, Volume 571, 2024). In particular, data of Shirazi et al. shows that the flux of the commercial membrane at 50 degrees Celsius is around 2 LMH, in comparison the membrane of the present invention at 50 84424PC01

[0279] 34 degrees Celsius is able to reach LMH in the range of 5 to 10 LMH (Figure 5). This proves that the membrane according to the invention has higher permeability performance.

[0280] Additionally, according to the data sheet of the MICRODYN, the membrane should operate in a temperature range of 5 to 40 degrees Celsius, while the membrane of the present invention can operate at up to 90 degrees Celsius, proving that the membrane according to the invention has a higher thermal stability.

[0281] Conclusion

[0282] The comparison of the membrane according to the present invention and the commercial membrane demonstrates that the membrane of the invention has an improved permeability performance and a higher thermal stability.

[0283] Example 7 - Membrane fabrication using nonreactive polymer as the porogen

[0284] Aim of study

[0285] In this study, the inventors used nonreactive polymers, such as polypropylene glycol (PPG), as porogen for membrane fabrication. Two layers of different nonwoven materials were employed as the substrate.

[0286] This example aims to demonstrate that:

[0287] I. The membrane can be fabricated on multiple substrate layers, resulting in an asymmetric structure.

[0288] II. Nonreactive polymer (e.g., PPG) can be used as porogen, with tunability of pore size; and

[0289] III. The resulting membrane can be used for thermal driven membrane processes.

[0290] Materials and methods

[0291] The membrane-coating solution was prepared essentially as described in Example 1 using the following components: Butyl-acrylate (CAS 141-32-2) as the monomer and trimethylolpropane triacrylate (CAS 15625-89-5) as the crosslinker. The porogen was PPG (Molecular weight 400 g / mol) at concentrations ranging from 60 wt% to 80 wt%, and 1 wt% of Irgacure 819 was added as the UV initiator. The membrane was coated and irradiated on one side in 50s with a UV- 405nm irradiation source.

[0292] To fabricate the membrane, two substrate layers, non-woven glass fiber (GF) and nonwoven melt blown polypropylene (MBPP), were used. Membrane parameters, including pore size, porosity, liquid entry pressure (LEP), and thickness, were 84424PC01

[0293] 35 measured, here done with capillary flow porometry (porolux 1000), wetting dewetting method, pressure test (Sterlitech HP4750 high-pressure stirred dead-end cell) and micrometer (Mitutoyo 543-391B) respectively. The membrane prepared with 70 wt% porogen concentration was tested in the membrane distillation system, similar to the tests described in Example 3 and Example 4, equipped with a heating unit operating at 70 °C.

[0294] Results

[0295] The membrane consisted of two substrate layers, non-woven materials MBPP and GF. Images of each material layer are shown in Figure 12. After coating, the MBPP layer (Figure 12B) provided selectivity, while the GF layer (Figure 12A) provided mechanical strength. These results indicate that a double-layer substrate yields an asymmetric membrane structure.

[0296] In this example, PPG was used as porogen. Four membranes with increasing PPG concentrations (60-80 wt%) were fabricated. As the PPG concentration increased, the pore size increased from 85nm to 333nm (Figure 13). This demonstrates that PPG can be used as a porogen during membrane fabrication, and that the pore size can be adjusted by increasing or decreasing the porogen concentration.

[0297] In this study, the inventors further characterized membranes fabricated with 70wt% of PPG. Liquid entry pressure (LEP), porosity, and thickness were each measured in triplicate to improve accuracy and quantify variability. As summarized in Table 1, the average values were 3.7 bar for LEP, 71.1% for porosity, and 436.7 pm for thickness. The high LEP indicates a highly hydrophobic surface with strong anti-wetting behavior, which is essential for stable membrane distillation (MD) operation. As expected, porosity correlated positively with the porogen concentration, reflecting the formation of more (and / or larger) pores at higher loadings.

[0298] Table 1: Physical properties, including liquid entry pressure (LEP, bar), porosity

[0299] (%), and thickness ( m) of a membrane fabricated with 70% of porogen (PPG). 84424PC01

[0300] 36

[0301] To evaluate MD performance, a membrane fabricated with 70% concentration of PPG was tested in a crossflow MD module. The feed side was operated at 70 °C using a heater and the permeate side at 15 °C using a cooler, with a 50 g L- 1NaCI solution as the feed. As shown in Figure 14A, the system exhibited stable performance under these operating conditions: The permeate flux remained approximately 10 LMH (L m-2h- 1) over 8 h of operation. The permeate conductivity (Figure 14B) stabilized at about 40 pS cm- 1, while the feed conductivity was about 67090 pS cm- 1, corresponding to a salt rejection of approximately 99.94%. Conclusion

[0302] Collectively, the morphology images (GF vs. MBPP), the pore size-concentration trend, and the property summary (LEP, porosity, thickness) establish a clear structure-property-performance relationship for the fabricated membranes. Using double-layer nonwoven materials enables asymmetric membrane architecture. Increasing the porogen (PPG) concentration tuned the average pore size (from 85 to 333 nm) while maintaining practical LEP and porosity ranges. Under cross-flow MD with a 50 g L- 1NaCI feed and feed / permeate temperatures of 70 / 15 °C, the membrane with 70% of porogen (PPG) delivered stable operation for 8 h, sustaining a flux of ~10 LMH (L m-2h- 1). The permeate conductivity stabilized at ~40 pS cm- 1, corresponding to ~99.4% salt rejection.

[0303] These results indicate robust wetting resistance and consistent desalination performance, highlighting the membrane fabrication method as a promising route to balance permeability and selectivity in membrane distillation.

[0304] Example 8 - Application of the membranes in pressure filtration experiments

[0305] Aim of study

[0306] The aim of this study was to test whether membranes of the present invention were capable of being used in a pressurized filtration system, i.e., applications for selectively separating solutes from solvents. This was done using synthetic solutions with a target solute (Bovine heamoglobin - BH) and biocrude streams of pressed spinach (PS) where the target solute was the common protein RuBisCo. Materials and methods Recovery of BH

[0307] For the recovery of BH a membrane with Meltblown polypropylene as substrate was used, the active layer solution consisted of Butyl-acrylate (CAS 141-32-2) as 84424PC01

[0308] 37 the monomer and trimethylolpropane triacrylate (CAS 15625-89-5) as the crosslinker in a 60 wt% / 40 wt% ratio respectively. The pore-forming agent was Polypropylene glycol (CAS 25322-69-4, molecular weight 400 g / mol) which was added in a 60 wt% / 40 wt% for the pore-forming agent and the active layer solution respectively. Lastly 2.5 wt% Irgacure 819 was added to the final resin as photoinitiator. See Example 1 for a detailed description of the membrane fabrication process. The membrane was coated and irradiated for 100s with a UV- 405nm irradiation source.

[0309] The finished membrane was tested in a Sterlitech HP4750 high-pressure stirred dead-end cell, with 400RPM stirring under 4 bars of pressure. The concentration of streams was analyzed by spectrophotometry.

[0310] Recovery of Ru BisCo

[0311] For the recovery of RuBisCo protein from the biocrude pressed spinach (PS) a membrane with Tyvek HDPE (Flashspun High density polyethylene fiber) as a substrate was used. The active layer solution consisted of Butyl-acrylate (CAS 141-32-2) as the monomer and trimethylolpropane triacrylate (CAS 15625-89-5) as the cross-linker in a 60wt% / 40wt% ratio respectively. The pore-forming agent was Decan-l-ol which was added in a 60wt% / 40wt% for the pore-forming agent and the active layer solution respectively. Lastly 2.5wt% Irgacure 819 was added to the final resin as photoinitiator. The membrane was coated and irradiated for 100s with a UV-405nm irradiation source. See Example 1 for a detailed description of the membrane fabrication process.

[0312] The finished membrane was tested in a MILLIPORE Stirred Ultrafiltration Cell 8200, with 200RPM stirring under different pressures. The RuBisCo protein was analysed via SDS-PAGE electrophoresis.

[0313] Results

[0314] Recovery of BH

[0315] The resulting membrane permeabillity from the filtration of BH was approximately lOLMH / bar throughout the experiment. The permeate solution was analysed for the presence of BH. The feed concentration was 250ppm. The Concentration of the permeate was characterized spectrophotometrically to be 0.2 - 0.6ppm, a rejection of >99.8% of the solute BH. The membrane also showed clear signs of rejection as the top part of the membrane (part towards the feed) would be coated with a red coat, indicative of Heamoglobin, and the permeate side of the membrane would remain pristine white Figure 15. 84424PC01

[0316] 38

[0317] Recovery of RuBisCo

[0318] PS was filtrated with the membrane with the aim of filtrating unwanted compounds such as colloids and debris, leaving mostly only the protein RuBisCo behind. This was done under a 2.5 bar constant pressure. The permeate product was analysed with SDS-PAGE as seen in Figure 16A, B and C, which shows that the bands characteristic for RuBisCo (116kDa, 45 kDa, 35 kDa, 25 kDa, 18.4 kDa and 14,4kDa) were present in the permeate. A small green tail seen in Figure 16A was gone in the filtrate suggesting that the green particulates had been successfully rejected while the proteins had been allowed to pass. This was further validated by the color of the filtrate, in which no green color was present (data not shown). The overall flux is shown in Figure 16D, with a performance of approximately 10-11 LMH that remained relatively stable.

[0319] Conclusion

[0320] The present example demonstrates that membranes of the present invention can be used in pressure filtration experiments to separate solutes from solvents and separate specific solutes from other solutes.

[0321] References

[0322] WO16081541 Al

[0323] US2022288538 Al

Claims

84424PC0139Claims1. A method for producing a membrane comprising the steps of: a) providing at least one monomer and / or oligomer, b) optionally, mixing the at least one monomer and / or oligomer with a cross-linker, c) adding at least one pore-forming agent to the mixture comprising the monomer and / or oligomer, d) adding an initiator and at least one substrate, followed by e) activating the initiator.

2. The method according to claim 1, wherein the monomer or oligomer is a linear molecule comprising radical polymerizable functional groups, such as acryloyl, epoxides, and isocyanates.

3. The method according to any one of claims 1 or 2, wherein the monomer and / or oligomer is selected from the group consisting of acrylates, methacrylates, epoxides, polyols, isocyanates, and siloxanes, or a mixture thereof.

4. The method according to any one of the preceding claims, wherein the monomer and / or oligomer is selected from the group consisting of Ci-Cs-alkyl- acrylate, Ci-Cs-alkyl-methacrylate, hydroxy(Ci-C8-alkyl)-methacrylate, phenolic epoxy resin, Methyl Methacrylate, 2-, tert-butyl acrylate, Methoxy Polyethylene Glycol Acrylate, 2-ethylhexyl acrylate, Styrene, Glycidyl Methacrylate, Perfluorohexylethyl Acrylate, Perfluorodecyl Acrylate or a mixture thereof, preferably butyl-acrylate or (hydroxyethyl)methacrylate.

5. The method according to any one of the preceding claims, wherein the crosslinker is a molecule containing radical polymerizable functional groups, such as acryloyls, epoxides, and isocyanates.

6. The method according to any one of the preceding claims, wherein the crosslinker is selected from the group consisting of 1,6-Hexanediol diacrylate (HDDA), Trimethylolpropane triacrylate (TMPTA), Pentaerythritol triacrylate (PETA), Ethoxylated trimethylolpropane triacrylate (ETMPTA), Dipentaerythritol84424PC0140 pentaacrylate (DPEPA), 1,4-Butanediol diacrylate (BDDA), Tripropylene glycol diacrylate (TPGDA), Bisphenol A ethoxylate diacrylate (BPAEDA), Polyethylene glycol diacrylate (PEGDA), Glycerol propoxylate triacrylate (GPTA), Bisphenol A diglycidyl ether (BADGE), Bisphenol F diglycidyl ether (BFDGE), 1,4-Butanediol diglycidyl ether (BDE), Cycloaliphatic diepoxide (e.g., 3,4-epoxycyclohexylmethyl- 3,4-epoxycyclohexane carboxylate), preferably trimethylolpropane triacrylate.

7. The method according to any one of the preceding claims, wherein the poreforming agent is selected from the group consisting of a C2-C12 alcohol, polyol, such as poly(glycol), or copolymer thereof, organic solvent, C3-C20 fatty acid, and C3-C20 triglyceride, preferably C2-C12 alcohol or poly(glycol).

8. The method according to claim 7, wherein the pore-forming agent is selected from the group consisting of propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, propylene glycol, butanediol, 1,2,3-propanetriol (Glycerin), erythritol, xylitol, polypropylene glycol, polyethylene glycol, poly(ethylene glycol-propylene glycol) copolymers, polytetra methylene ether glycol, acetone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, acetonitrile, tetra hydrofuran, and l-Methyl-2-pyrrolidone, or a mixture thereof, preferably polypropylene glycol or decan-l-ol.

9. The method according to any one of the preceding claims, wherein the substrate is a fibrous substrate, preferably a non-woven fibrous substrate.

10. The method according to any one of the preceding claims, wherein the substrate is selected from the group consisting of polypropylene fiber, such as melt blown polypropylene fiber, polyethylene fiber, such as flashspun high density polyethylene fiber (HDPE), cellulose fiber, glass fiber, and ceramic fiber, such as ceramic wool or ceramic paper, preferably cellulose fiber, ceramic fiber, polypropylene fiber, or glass fiber, more preferably cellulose fiber, ceramic fiber or polypropylene fiber.

11. The method according to any one of the preceding claims, wherein the initiator is a photoinitiator or a thermal initiator.84424PC014112. The method according to any one of the preceding claims, wherein the initiator is a photoinitiator, preferably a UV initiator.

13. The method according to any one of the preceding claims, wherein step d) further comprises adding an inhibitor, preferably wherein the inhibitor is selected from the group consisting of Hydroquinone monomethyl ether (MEHQ), Phenothiazine, BHT (Butylated Hydroxytoluene), Copper(I) chloride (CuCI), N,N- Diethylaniline (DEA), and Diphenylamine, or a mixture thereof.

14. The method according to any one of the preceding claims, wherein the activation of the initiator is conducted by irradiation, such as irradiation with UV light, or heat treatment.

15. A membrane obtained by or obtainable by the method according to any one of the preceding claims.

16. A membrane comprising a substrate coated with a porous polymer composed of cross-linked monomers and / or cross-linked oligomers having radical polymerizable functional groups, such as acryloyls, epoxides, and isocyanates.

17. The membrane according to any one of claims 15 or 16, wherein the membrane is a hydrophobic or hydrophilic membrane.

18. The membrane according to any one of claims 15-17, wherein the substrate is a fibrous substrate, preferably a non-woven fibrous substrate.

19. The membrane according to any one of claims 15-18, wherein the membrane is symmetrical or asymmetrical, preferably symmetrical.

20. Use of the membrane according to any one of claims 15-19 for electrochemical membrane processes, such as electrodialysis, electro filtration or electro osmosis, for concentration gradient, such as dialysis, gas separation or pervaporation, for thermal gradient, such as membrane distillation, membrane assisted crystallization or thermally assisted reverse osmosis, for pressure84424PC0142 gradient, such as reverse osmosis, nanofiltration, ultrafiltration, microfiltration, oil water separation, or dairy separation.

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