Porous polymer film containing a pattern arrangement of through-holes and method for manufacturing the same

Abstract

A porous polymer film is provided. The porous polymer film includes a first outer surface having a pattern arrangement of first pores with irregularly shaped periphery, a second outer surface on the opposite side having a plurality of second pores, and a polymer matrix present between the first and second outer surfaces. The polymer matrix defines a plurality of through-pores present between the first and second pores. A method for producing a porous polymer film includes applying a casting solution to a tool structure having a main surface and a pattern arrangement of projections extending orthogonally from the main surface to form a layer of the casting solution. The casting solution includes a polymer component and a solvent system. The method further includes contacting the layer of casting solution with a non-solvent fluid to solidify the polymer component and form a porous polymer film, and removing the porous polymer film from the tool structure, thereby providing a porous polymer film.

Description

Technical Field

[0001] The present disclosure generally relates to porous polymer membranes.

Summary of the Invention

[0002] In a first aspect, a porous polymer membrane is provided. The porous polymer membrane includes: a) a first outer surface having a pattern arrangement of first holes with irregular-shaped peripheries; b) an opposite second outer surface having a plurality of second holes; and c) a polymer matrix present between the first outer surface and the second outer surface. The polymer matrix defines a plurality of through holes present between the first holes and the second holes.

[0003] In a second aspect, a method is provided. The method includes applying a casting solution to a tool structure having a main surface and a pattern arrangement of protrusions extending orthogonally therefrom to form a layer of the casting solution. The casting solution includes a polymer component and a solvent system. The method further includes contacting the layer of the casting solution with a non-solvent fluid to solidify the polymer component and form a porous polymer membrane, and removing the porous polymer membrane from the tool structure, thereby providing a porous polymer membrane. The porous polymer membrane includes: 1) a first outer surface having a pattern arrangement of first holes with irregular-shaped peripheries that do not correspond to the shapes of the tops of the plurality of protrusions; 2) an opposite second outer surface having a plurality of second holes; and 3) a polymer matrix present between the first outer surface and the second outer surface. The polymer matrix defines a plurality of through holes present between the first holes and the second holes.

[0004] The above summary of this disclosure is not intended to describe each disclosed embodiment or any embodiment of this disclosure. The following description illustrates exemplary embodiments in more detail. Throughout this specification, guidance is provided by lists of examples, which may be used in various combinations. In each case, the lists provided are representative and should not be construed as exclusive lists. [Brief explanation of the drawing]

[0005] [Figure 1] This is a schematic perspective view of a porous polymer film according to one embodiment of the present disclosure.

[0006] [Figure 2A] This is a scanning electron microscope (SEM) image of a portion of the first surface of an impregnated three-dimensional article according to one embodiment of the present disclosure.

[0007] [Figure 2B] Figure 2A shows a SEM image of a portion of the second surface of an infiltrated three-dimensional article according to the embodiment.

[0008] [Figure 3] This is a flowchart of the method according to one embodiment of the present disclosure.

[0009] [Figure 4] This is a schematic cross-sectional view of a porous polymer film formed on a tool structure, where the pores on the surface of the film do not correspond to the shape of the upper part of the protrusions on the tool structure.

[0010] [Figure 5] This is a schematic cross-sectional view of a tool structure having a projection with a trunk and a head, used in the method according to this disclosure.

[0011] The drawings above illustrate various embodiments of the present disclosure, but other embodiments are also conceivable, as described below. In all cases, this disclosure presents the invention representatively and not as an limitation. The drawings are not necessarily to scale. The same numbers used in the drawings indicate the same component. However, it should be understood that a number used to indicate a component in one drawing is not intended to limit the components shown with the same number in other drawings. [Modes for carrying out the invention]

[0012] Glossary

[0013] The term "diameter" refers to the longest measurable distance along the cross-section of an element (e.g., a hole, through hole, projection head, projection trunk). The average diameter is the average of 25 or more measured diameters.

[0014] The term "microporous" refers to having multiple pores with an average size (and sometimes diameter) of up to 500 micrometers. At least some of these pores must have dimensions equal to or greater than the wavelength of visible light. For example, at least some of the pores must have dimensions (and sometimes diameter) of at least 400 nanometers. Pore size is measured by measuring the bubble point according to ASTM F-316-80.

[0015] The thickness of a film should be understood as the smallest dimension of the film. This is generally referred to as the "z" direction and indicates the distance between the main surfaces of the film.

[0016] The term "upstanding" in relation to tool protrusions refers to posts that project from a main surface, including posts that stand perpendicular to the main surface and posts whose angle to the main surface is not 90 degrees.

[0017] As used herein, “aliphatic group” means a saturated or unsaturated linear, branched, or cyclic hydrocarbon group. This term is used to include, for example, alkyl, alkenyl, and alkynyl groups. “Alkyl” refers to a linear or branched, cyclic, or acyclic saturated monovalent hydrocarbon having 1 to 32 carbon atoms, such as methyl, ethyl, 1-propyl, 2-propyl, and pentyl. “Alkylene” refers to a linear saturated divalent hydrocarbon having 1 to 12 carbon atoms, or a branched saturated divalent hydrocarbon group having 3 to 12 carbon atoms, such as methylene, ethylene, propylene, 2-methylpropylene, pentylene, and hexylene. “Alkenyl” and “ene” refer to a linear or branched unsaturated aliphatic monovalent group having one or more carbon-carbon double bonds, such as vinyl.

[0018] As used herein, the term "(meth)acrylate" is an abbreviation for acrylate, methacrylate, or a combination thereof; "(meth)acrylic" is an abbreviation for acrylic, methacrylic, or a combination thereof; and "(meth)acryl" is an abbreviation for acrylic group and methacrylic group. "Acrylic" refers to derivatives of acrylic acid, such as acrylate, methacrylate, acrylamide, and methacrylamide. "(meth)acryl" means a monomer or oligomer having at least one acrylic or methacrylic group, linked by an aliphatic segment if it contains two or more groups. As used herein, "(meth)acrylate-functional compound" means a compound containing a (meth)acrylate substructure.

[0019] As used herein, the term or prefix "micro" refers to at least one dimension defining a structure or shape being in the range of 1 micrometer to 1 millimeter. For example, a micro structure may have a height or width in the range of 1 micrometer to 1 millimeter.

[0020] As used herein, "resin" includes all polymerizable components (monomers, oligomers, and / or polymers) present in a curable composition. The resin may contain only one type of polymerizable component or may contain a mixture of different polymerizable components.

[0021] As used herein, the "glass transition temperature (Tg)" of a polymer refers to the temperature at which the polymer transitions from a glassy state to a rubbery state, and is measured, for example, by differential scanning calorimetry (DSC) at a heating rate of 10 °C / min under a nitrogen atmosphere. Appropriate DSC measurement methods and analysis methods are described in J. Polym. Sci. A., Polym. Chem. 1993, 31, 2531 - 2539 by Matsumoto, A. et al.

[0022] As used herein, "thermoplastic" refers to a polymer that flows when heated sufficiently above its glass transition point and becomes solid upon cooling.

[0023] As used herein, "thermoset" refers to a polymer whose shape is permanently fixed by curing and does not flow upon subsequent heating. Thermoset polymers are typically cross-linked polymers.

[0024] The terms "preferably" and "preferred" refer to embodiments of the present disclosure that may provide certain advantages under certain circumstances. However, in the same or other circumstances, other embodiments may be preferred. Further, the fact that one or more preferred embodiments are described does not mean that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the present disclosure.

[0025] In this application, the words "a", "an", and "the" are not intended to refer only to a single object, but rather to encompass the entire general classification for which specific examples are used for illustration. The words "a", "an", and "the" are used synonymously with the phrase "at least one". When a list follows the phrases "at least one ~" and "including at least one ~", it refers to any one element within the list, or any combination of two or more elements.

[0026] In this specification, the word "or" is used in its ordinary meaning unless otherwise specified, and includes "and / or". The phrase "and / or" means any one or all of the listed elements, or any combination of two or more elements.

[0027] Also, in this specification, all numerical values are considered to be modified by "about", and preferably by "exactly". As used herein, "about" in relation to a measured quantity means the variation that would be expected if a person of ordinary skill in the art were to make the measurement with a level of care appropriate to the purpose and the precision of the measuring equipment used. Further, when a numerical range is described by its endpoints, it is to be understood to include all numerical values and endpoints within that range (e.g., for 1 - 5, it includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0028] In this specification, "generally" as used to modify properties or attributes means, unless otherwise defined, a property or attribute that can be easily recognized by a person skilled in the art without requiring absolute precision or perfect agreement (e.g., within ±20% of a quantitative property). "Substantially" means, unless otherwise defined, a high degree of approximation (e.g., within ±10% of a quantitative property), but still without requiring absolute precision or perfect agreement. Terms such as "identical," "equal," "uniform," "constant," and "exact" should also be understood within the normal tolerance or measurement error range appropriate to the context, and without requiring absolute agreement.

[0029] In membrane technology, a combination of high selectivity and high permeation flux is desirable. In filtration membranes (e.g., in biopharmaceutical processes), this addresses the challenge of producing large-area membranes with high pore density and uniform pores using simple techniques. Block copolymers have been widely studied in this regard due to their ability to self-assemble into regular structures, which can lead to high pore density. However, the block copolymer approach tends to suffer from several significant constraints, such as limited chemical structure options and the high cost of block copolymers.

[0030] The "cast and precipitate (CAP)" process, which combines micro-replication or nano-replication with film formation in a single step, has been found to be usable for forming porous polymer films with high selectivity and high permeation flux. Here, a polymer solution cast onto a tool structure containing upward-projecting protrusions undergoes non-solvent-induced phase separation (NIPS) in contact with the tool surface. As the polymer precipitates, the thickness-direction shrinkage associated with the process penetrates the post, forming through-holes. Lateral shrinkage allows the polymer film to be easily peeled from the tool. While other microfabrication methods require post-processing such as etching or heat treatment for through-hole formation, CAP enables etching-free, single-step continuous manufacturing. The CAP process is generally compatible with any ternary system (polymer-solvent-non-solvent) combination and offers significant advantages from a commercialization and scale-up perspective.

[0031] A suitable tool surface may include projections having both a head and a trunk, and it was unexpectedly discovered, as detailed below, that the formed porous polymer film can be removed from the projections without the walls of the through-holes being destroyed by the heads.

[0032] [Porous polymer film] In a first aspect, a porous polymer film is provided. The porous polymer film includes:

[0033] a) A first outer surface having a pattern arrangement of first holes with irregularly shaped peripheries;

[0034] b) A second outer surface on the opposite side having a plurality of second holes; and

[0035] c) A polymer matrix that exists between a first outer surface and a second outer surface, and defines a plurality of through-pores that exist between a first pore and a second pore.

[0036] Referring to Figure 1, the porous polymer membrane 100 includes a first outer surface 110 having a patterned arrangement of first pores 120 with irregularly shaped peripheries, an opposite second outer surface 130 having a plurality of second pores 140, and a polymer matrix 150 extending between the first outer surface 110 and the second outer surface 130. The polymer matrix 150 defines a plurality of through-holes 160 extending between the first pores 120 and the second pores 140, the through-holes being surrounded by walls 170. In this case, the patterned arrangement includes a grid of pores arranged along columns and rows at (approximately) equal intervals from adjacent pores. Any intentional pattern useful for filtration is suitable for the arrangement. In the embodiment shown in Figure 1, the plurality of second pores 140 have regularly shaped peripheries, such as circular peripheries. Furthermore, the first hole 120 has a smaller size (e.g., diameter) than the second hole 140, and generally includes a group of four small holes instead of one large hole.

[0037] The term "irregular" with respect to the periphery of a hole refers to a periphery that has an uneven or unbalanced shape. Often, the periphery of an irregularly shaped hole is asymmetrical due to a lack of uniformity or balance found in other symmetrical shapes (e.g., equilateral triangles, circles, squares, etc.). For example, an irregularly shaped circular hole has a periphery that is not a perfect circle; see, for example, the hole shown at reference number 224 in Figure 2A. To satisfy the definition that multiple holes have irregularly shaped peripheries, not all holes need to be irregularly shaped; rather, 25% or more of multiple holes need to have irregularly shaped peripheries, and 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% or more need to have irregularly shaped peripheries. The shape and / or size of the holes can be determined by any well-known microscopic method. For example, optical microscopy or scanning electron microscopy can be used in combination with any image analysis software. For instance, the National Institutes of Health (NIH, Bethesda, MD) offers software called "IMAGE J" as freeware.

[0038] As described above, the tool surface used in the cast-and-precipitate process may include projections having both a head and a trunk, and it has been unexpectedly found that the formed porous polymer film can be removed from the projection without the walls of the through-holes being destroyed by the head of the projection. In some cases, the removal of the porous polymer film may cause cracks to form around at least some of the holes on the first or second outer surface as the film passes through the head. For example, Figure 2A shows a crack 222 at the periphery of a hole 220 on the surface 210 of a porous polymer film 200. One advantage of using projections with heads and trunks is that the head can help hold the layer of casting solution in place on the tool structure during the deposition process for film formation (e.g., when immersed in a non-solvent fluid), thereby reducing the possibility of the film unintentionally peeling off the tool structure prematurely.

[0039] In one embodiment, the first and second pores have peripheries that differ from each other in at least one of the following ways: shape (e.g., regular or irregular) or size. Figures 2A and 2B show examples of first and second pores 220 and 240 having different pore sizes. More specifically, Figure 2A is a scanning electron microscope (SEM) image of a portion of the first surface 210 of a porous polymer film 200 made of polyethersulfone, which includes a plurality of first pores 220 having irregularly shaped peripheries. Through-holes 260 and the polymer matrix 250 are visible through at least some of the first pores 220. Figure 2B is an SEM image of a portion of the second surface 230 of the polymer film 200, which includes a plurality of second pores 240. Compared to the plurality of first pores 220 in Figure 2A, the plurality of second pores 240 have different shapes (irregular ellipses) and different sizes (smaller). This result was achieved by applying a layer of casting solution with a thickness greater than the height of the projection to the tool structure. The projection has a head shape on the trunk, particularly a T-shape, with the outer edge of the head tending to form the second hole 240. For example, the four second holes 240 in Figure 2B correspond to the positions of the four edges of the head (e.g., the top of the "T") of one trunk, respectively. In this embodiment, the second holes 240 have an average area of ​​less than half the average area of ​​the first holes 220. In another embodiment, the first holes may have an average area of ​​less than half the average area of ​​the second holes.

[0040] Furthermore, in the embodiments shown in Figures 2A and 2B, the polymer matrix 250 adjacent to the through-hole 260 and extending between the first surface 210 and the second surface 230 is porous. In another embodiment, the polymer matrix adjacent to the through-hole is non-porous. Often, the distance between adjacent through-holes affects whether the polymer matrix is ​​porous; if the distance is small (e.g., less than 10 micrometers), it is likely to be a non-porous polymer matrix.

[0041] In one embodiment, the first and second holes may have similar hole sizes but different hole shapes. For example, a plurality of first holes may have irregularly shaped peripheries (e.g., irregular circles), while a plurality of second holes may have a different shape from the plurality of first holes (e.g., regular circles). This can be achieved by applying a layer of casting solution with a thickness less than the height of the protrusions to the tool structure. The protrusions may have a shape with a head on a trunk, and when the porous polymer film is removed from the tool structure, at least some of the peripheries of the first holes tend to deform and become irregularly shaped.

[0042] In many cases, at least one of the through-pores, first pores, or second pores of a porous polymer film is 1 micrometer or larger, 2 micrometers, 3 micrometers, 5 micrometers, 7 micrometers, 10 micrometers, 12 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, 90 micrometers, 100 micrometers, 110 micrometers, 120 micrometers, etc. The through-holes have an average diameter of 1 micrometer, 120 micrometers, 140 micrometers, or 150 micrometers or more, and an average diameter of 500 micrometers or less, 475 micrometers, 450 micrometers, 425 micrometers, 400 micrometers, 375 micrometers, 350 micrometers, 325 micrometers, 300 micrometers, 275 micrometers, 250 micrometers, 225 micrometers, 200 micrometers, 190 micrometers, 180 micrometers, 170 micrometers, or 160 micrometers or less. In many embodiments, the through-holes have an average diameter of 1 micrometer to 500 micrometers, or 10 micrometers to 300 micrometers. For convenience, the average diameter of the through-holes is usually measured on either the first or second outer surface of the porous polymer film. Depending on the method for manufacturing the porous polymer film, the diameter of the through-holes may differ between the first and second outer surfaces along the thickness direction of the film, for example, when a tool structure having protrusions whose cross-section changes along the height of the protrusions is used. In the selected embodiment, the through-holes are isoporous. Isoporous through-holes can be provided by using a tool structure having protrusions of the same size.

[0043] The porous polymer film has a thickness between the first outer surface and the second outer surface of 1 micrometer or more, 2 micrometers, 5 micrometers, 7 micrometers, 10 micrometers, 12 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, 90 micrometers, 100 micrometers, 125 micrometers, 150 micrometers, 175 micrometers, 200 micrometers, 225 micrometers, 250 micrometers, 275 micrometers, and 300 micrometers. Chromometers, 325 micrometers, 350 micrometers, 400 micrometers, 450 micrometers, or 500 micrometers or more, and 5 millimeters (mm) or less, 4.5 mm, 4 mm, 3.5 mm, 3 mm, 2.5 mm, 2 mm, 1.5 mm, 1 mm, 950 micrometers, 900 micrometers, 850 micrometers, 800 micrometers, 750 micrometers, 700 micrometers, 650 micrometers, 600 micrometers, 550 micrometers, 500 micrometers, 450 micrometers, 400 micrometers, 350 micrometers, 300 micrometers, 250 micrometers, or 200 micrometers or less.

[0044] The through-holes / first holes have density on the first outer surface, and this density is determined by the density of protrusions on the main surface of the tool structure used to fabricate the porous polymer film. In one embodiment, the density of the first holes and through-holes on the first outer surface is per square centimeter (cm²). 2The number of holes per inch is 50 or more, 75, 100, 125, 150, 175, 200, 225, or 250 or more. The upper limit of the density of through holes and first holes is limited by the diameter of the heads of the projections on the tool structure. More specifically, if the heads of the projections are too close together (or in contact), it becomes difficult to remove the polymer matrix from the tool structure while retaining the through holes and / or holes in their entirety.

[0045] The polymer matrix includes polyethersulfone, polypropylene, polysulfone, polyacrylonitrile, cellulose ester, polyimide, polyamide, poly(vinylidene fluoride), or poly(tetrafluoroethylene). In selected embodiments, the polymer matrix includes polyethersulfone or amorphous nylon. Suitable commercially available polyethersulfones are available from BASF (Wyandotte, MI) under the trade names "ULTRASON E6020" and "ULTRASON E7020". Suitable commercially available amorphous nylon is available from Evonik Industries (Essen, Germany) under the trade name "TROGAMID CX9704".

[0046] [method] In a second aspect, the present disclosure provides a method comprising the following steps:

[0047] A step of applying a casting solution to a tool structure including a main surface and a pattern arrangement of protrusions extending perpendicularly from the main surface to form a layer of the casting solution, wherein the casting solution includes a polymer component and a solvent system;

[0048] A step of solidifying polymer components by bringing a layer of casting solution into contact with a non-solvent fluid to form a porous polymer film; and

[0049] A process for removing a porous polymer film from a tool structure; This provides a porous polymer film, which includes the following:

[0050] 1) A first outer surface having a pattern arrangement of first holes having irregularly shaped peripheries that do not correspond to the shapes of the tops of multiple protrusions;

[0051] 2) A second outer surface on the opposite side having a plurality of second holes; and

[0052] 3) A polymer matrix that exists between a first outer surface and a second outer surface, and defines a plurality of through-pores that exist between a first pore and a second pore.

[0053] Referring to Figure 3, a flowchart of a method according to one embodiment of the present disclosure is shown. The method comprises step 310, which is the step of applying a casting solution to a tool structure including a main surface and a pattern arrangement of protrusions extending orthogonally from the main surface to form a layer of casting solution, the casting solution comprising a polymer component and a solvent system. In one embodiment, the layer of casting solution has a thickness less than the height of the protrusions, while in another embodiment, the layer of casting solution has a thickness equal to the height of the protrusions. Typically, using a layer of casting solution with a thickness equal to or less than the height of the protrusions results in a deposited film with a thickness less than the height of the protrusions due to shrinkage during the deposition process. In one embodiment, the layer of casting solution has a thickness greater than the height of the protrusions. An advantage is that, as shown in Figure 2B and above, using a layer of casting solution with a thickness greater than the height of the protrusions can result in a porous polymer film having pores smaller than the size of the top of the protrusions (e.g., the size of the head of the protrusions). The casting solution may be applied to the tool structure by any suitable means, including, but not limited to, roller coating, flow coating, dip coating, spin coating, spray coating, knife coating, or die coating.

[0054] Typically, casting solutions contain solids of 5% by weight or more, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15% by weight or more; and 50% by weight or less, 47%, 45%, 42%, 40%, 37%, 35%, 32%, 30%, 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, or 12% by weight or less. If the solids content is less than 5% by weight, the resulting porous polymer film tends to shrink significantly, and the through-holes tend to be substantially larger than the size of the projections of the tool structure. When the solids content exceeds 50% by weight, the viscosity tends to become too high, making it difficult to cast properly onto the tool structure.

[0055] Any polymer-solvent-non-solvent combination can be used to form a polymer film in a cast-and-plipitate process according to the method of this disclosure. For example, the polymer component may optionally include polyethersulfone, polypropylene, polysulfone, polyacrylonitrile, cellulose ester, polyimide, polyamide (e.g., amorphous nylon), poly(vinylidene fluoride), or poly(tetrafluoroethylene). In selected embodiments, the polymer component includes polyethersulfone or amorphous nylon, the solvent system includes dimethyl sulfoxide, and the non-solvent fluid includes water.

[0056] Examples of solvents used in the casting solution include water, dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, tetramethylurea, acetone, methyl ethyl ketone, methyl acetate, ethyl acetate and other alkyl acetates, dimethyl sulfoxide, and combinations thereof. The solvent may be an oligomer or a polymer, and may form a polymer blend with polymer components. The solvent may contain one or more solvents, a mixture of solvents, or a non-solvent for the phase transition. A non-solvent is a substance that is miscible with the solvent of the dope solution but is insoluble in the polymer on its own or causes polymer coagulation. Non-solvents may be added to the solvent to influence the rate of the phase transition or to aid in the formation of microstructures.

[0057] The selection of a solvent to provide a stable and homogeneous solution for casting in film formation involves fundamental principles regarding polymer solubility. Polymer solvents can be classified into good solvents, non-solvents, and poor solvents. A good solvent is one in which the interaction (force) between polymer molecules and solvent molecules is stronger than the attractive forces between polymer molecules. In contrast, the opposite is true for non-solvents. A poor solvent is one in which the interaction between the polymer and the solvent is equal to the attractive forces between polymer molecules. Good solvents can dissolve large amounts of polymer and are miscible with polymers at concentrations of 5% by weight or more, whereas poor solvents may or may not be miscible depending on the molecular weight of the polymer and the type of solvent. For example, if the polymer is polyethersulfone, examples of good solvents for polyethersulfone include dimethylacetamide, dioxane, dimethyl sulfoxide, N-methyl-2-pyrrolidone, chloroform, tetramethylurea, formic acid, and tetrachloroethane. Another method for evaluating the solubility of a solvent for a polymer is the Hildebrand solubility parameter. These parameters are solubility parameters expressed as the square root of the cohesive energy density of the material, and their unit is (pressure). 1 / 2 (ΔH-RT) 1 / 2 V 1 / 2Equivalent to ΔH = ΔH, where ΔH is the molar enthalpy of vaporization of the material, R is the gas constant, T is the absolute temperature, and V is the molar volume of the solvent. Hildebrand's solubility parameters are described in the following literature: Barton, AFM, “Handbook of Solubility and Other Cohesion Parameters” 2nd edition, CRC Press, Boca Raton, FL. (1991); for monomers and representative polymers, “Polymer Handbook” 4th edition, edited by J. Brandrup and EH Immergut, John Wiley, NY, pp. VII 675-714 (1999); for many commercial polymers, Barton, AFM, “Handbook of Polymer-Liquid Interaction Parameters and Solubility Parameters”, CRC Press, Boca Raton, FL. (1990).

[0058] The method also includes step 320 of contacting a layer of casting solution with a non-solvent fluid to solidify the polymer components and form a porous polymer film. A suitable non-solvent may be determined as detailed above. Furthermore, the method includes step 330 of removing the porous polymer film from the tool structure (e.g., by peeling it off the tool structure), thereby providing the porous polymer film.

[0059] The porous polymer film includes: 1) a first outer surface having an irregularly shaped periphery and a pattern arrangement of first pores that do not correspond to the shapes of the tops of a plurality of protrusions; 2) a second outer surface on the opposite side having a plurality of second pores; and 3) a polymer matrix present between the first and second outer surfaces. Furthermore, the polymer matrix defines a plurality of through-pores present between the first and second pores. The porous polymer film may conform to any embodiment of the first aspect described in detail above.

[0060] Referring to Figure 4, a schematic cross-sectional view of the porous polymer film 400 is shown, which is formed on the tool structure 490, and the holes on the first outer surface 410 of the film 400 do not correspond to the shape of the top 484 of the projection 480 of the tool structure 490. Rather, the holes correspond to the shape of the trunk 482 of the projection 480, which has a different shape from the top (e.g., head) 484. In the illustration in Figure 4, the holes are filled with the projection 480 because the porous polymer film 400 has not yet been removed from the tool structure 490. The second outer surface 430 on the opposite side of the film 400 is located adjacent to the tool structure 490.

[0061] In many cases, the projection of a tool structure includes a post (e.g., a trunk) and a head, with the post extending roughly perpendicularly from the main surface of the tool structure and the head positioned away from the main surface of the tool structure. In embodiments in which the projection has a head on a trunk, preferably the first pores of the resulting porous polymer film have an average pore diameter smaller than that of the head of the projection.

[0062] In some embodiments, the projections may be T-shaped, nail-shaped, mushroom-shaped (e.g., with a circular or elliptical head enlarged relative to the stem), or a combination thereof. For example, as shown in Figure 5, the tool structure 510 may include a backing 514 having a first face 516 and a second face 518 opposite the first face 516. An upwardly projecting stem 520 extends from the first face 516 of the backing 514, and each stem 520 has a proximal end 522 continuous with the first face 516 of the backing 514 and a distal end (i.e., head) 524 opposite the proximal end 522. The distal ends 24 of the post 20 do not need to be identical in shape and / or orientation within a single tool structure 510. In Figure 5, the main body 520 is positioned perpendicular to the backing material 514, but the main body 520 may be inclined at an angle of, for example, 45 to 90 degrees, 60 to 90 degrees, or 75 to 90 degrees.

[0063] The material composition of the tool structure includes an organic polymer. The organic polymer is not particularly limited and may be a thermoplastic polymer or a thermosetting polymer. Typical thermoplastic polymers include polyolefin homopolymers such as polyethylene, polypropylene, and polybutylene; copolymers of ethylene, propylene, and / or butylene, and copolymers and blends thereof; ethylene-containing copolymers such as ethylene vinyl acetate and ethylene acrylic acid; polyesters such as polyethylene terephthalate, polyethylene butyrate, and polyethylene naphthalate; polyamides such as poly(hexamethylene adipamide); polyurethanes; polycarbonates; poly(vinyl alcohol); ketones such as polyether ether ketone; polyphenylene sulfide; and mixtures thereof. In some embodiments, the thermoplastic polymer is a polyolefin (e.g., polyethylene, polypropylene, polybutylene, ethylene copolymer, propylene copolymer, butylene copolymer, copolymers and blends thereof), polyester, or a combination thereof. In selected embodiments, the tool structure is formed from polypropylene or a cross-linked (meth)acrylate polymer.

[0064] Any currently used method can be used to form the tool structure, for example, a configuration in which a molten resin containing an organic polymer and other additives is supplied between two rolls or between a nip formed between the die face and the roll surface, and at least one roll has a cavity. The cavity may be an inverted shape of a projection with a trunk and a head, or an inverted shape of a post without a head. The pressure applied by the nip pushes the resin into the cavity. In some embodiments, a vacuum may be used to facilitate cavity filling. The nip is usually wide enough to form a continuous backing material on the cavity. The die surface and cavity may be cooled with air or water before peeling off the backing material and post integrally molded by, for example, a stripper roll. After the projection is formed from the cavity, if it does not have a head, the head may be formed later by a capping method described in U.S. Patent No. 5,077,870 (Melbye et al.). Typically, the capping method involves deforming the tip portion of the projection by heat and / or pressure. Heat and pressure, when both are used, may be applied sequentially or simultaneously.

[0065] Other suitable tool rolls include those formed from a series of plates defining multiple protrusion-forming cavities around them, as described, for example, in U.S. Patent No. 4,775,310 (Fischer). The cavities may be formed on the plates, for example, by drilling or photoresist technology. Other examples include wire-wrapped rolls disclosed with a method of manufacture, such as in U.S. Patent No. 6,190,594 (Gorman et al.). Another typical method for forming protrusions in thermoplastic backings is the use of a flexible mold belt defining an array of post-shaped cavities, as described in U.S. Patent No. 7,214,334 (Jens et al.). Other useful methods for forming thermoplastic backings with protrusions are described in U.S. Patents No. 6,287,665 (Hammer), No. 7,198,743 (Tuma), and No. 6,627,133 (Tuma).

[0066] Another useful method for forming headed projections in thermoplastic backings is the profile extrusion method described in, for example, U.S. Patent No. 4,894,060 (Nestegard). In this method, a thermoplastic fluid is typically flowed through a patterned die lip (e.g., cut by electrical discharge machining) to form a web with ridges extending in the machine direction, which are then sliced ​​in a direction perpendicular to the machine direction, and the web is further stretched in the machine direction to form separated projections. The ridges form precursors to the projections and may exhibit the cross-sectional shape of the headed trunk. The thermoplastic backings of tool structures obtained by this method have a stretch-induced molecular orientation.

[0067] Specific examples of thermosetting polymers suitable for tool structures include crosslinked acrylates, such as monofunctional or polyfunctional acrylates, acrylated epoxy, acrylated polyester, and acrylated urethane, which are typically preferred, but not limited to, blends with monofunctional or polyfunctional monomers. These polymers are preferred for one or more of the following reasons: high heat resistance, environmental stability, transparency, and excellent release properties from tools or molds.

[0068] Other exemplary examples of materials suitable for forming tool structures include reactive resin systems that can be crosslinked by a free radical polymerization mechanism upon exposure to radiation such as electron beams, ultraviolet light, or visible light. Furthermore, these materials can also be polymerized by thermal methods by the addition of a thermal initiator such as benzoyl peroxide. Radiation-initiated cationic polymerizable resins may also be used. A reactive resin suitable for forming tool structures may be a blend of a photoinitiator and a compound having at least one acrylate group. Preferably, the resin blend contains monofunctional, difunctional, or polyfunctional compounds to ensure that a crosslinked polymer network is formed upon irradiation. Examples of usable resins that can be polymerized by a free radical mechanism include epoxy, polyester, polyether, and urethane-derived acrylic resins, ethylenically unsaturated compounds, aminoplast derivatives having at least one pendant-type acrylate group, isocyanate derivatives having at least one pendant-type acrylate group, epoxy resins other than acrylated epoxy, and mixtures and combinations thereof. The term "acrylate" is used to encompass both acrylates and methacrylates. U.S. Patent No. 4,576,850 (Martens) discloses an example of a crosslinked resin that may be used in the tool structures of this disclosure. Furthermore, polymerizable resins of the type disclosed in, for example, U.S. Patent No. 7,611,251 (Thakkar) may also be used in the tool structures of this disclosure.

[0069] The ethylenically unsaturated resins available herein include both monomers and polymers, which contain carbon, hydrogen, and oxygen atoms, and optionally nitrogen, sulfur, and halogens. Oxygen or nitrogen atoms, or both, are generally present in ether, ester, urethane, amide, or urea groups. The ethylenically unsaturated compounds are preferably esters obtained from the reaction of compounds containing aliphatic monohydroxylated or polyhydroxylated groups with unsaturated carboxylic acids (e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.). These materials are generally commercially available and readily crosslinkable.

[0070] Examples of compounds having acrylic or methacrylic groups suitable for use in tool structures are listed below:

[0071] (1) Monofunctional compounds:

[0072] Ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, n-hexyl acrylate, n-octyl acrylate, isooctyl acrylate, bornyl acrylate, tetrahydrofurfuryl acrylate, 2-phenoxyethyl acrylate, N,N-dimethylacrylamide;

[0073] (2) Bifunctional compounds:

[0074] 1,4-Butanediol diacrylate, 1,6-Hexanediol diacrylate, Neopentyl glycol diacrylate, Ethylene glycol diacrylate, Triethylene glycol diacrylate, Tetraethylene glycol diacrylate, Diethylene glycol diacrylate;

[0075] (3) Polyfunctional compounds:

[0076] Trimethylolpropane triacrylate, glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, tris(2-acryloyloxyethyl) isocyanurate. Monofunctional compounds tend to penetrate the overlay film material more quickly, while bifunctional and polyfunctional compounds tend to provide stronger, cross-linked bonds at the interface between the cube corner elements and the overlay film. Representative examples of other ethylenically unsaturated compounds and resins include styrene, divinylbenzene, vinyltoluene, N-vinylformamide, N-vinylpyrrolidone, N-vinylcaprolactam, monoallyl, polyallyl and polymetharyl esters, e.g., diallyl phthalate and diallyl adipate, and carboxylic acid amides, e.g., N,N-diallyl adipamide.

[0077] Examples of photopolymerization initiators that can be mixed with acrylic compounds in the tool structures of this disclosure include: benzyl, methyl o-benzoic acid esters, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzophenone / tertiary amines, acetophenones (e.g., 2,2-diethoxyacetophenone), benzyl methyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-benzyl-2-N,N-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2-methyl-1-4-(methylthio)phenyl-2-morpholino-1-propanone, bis(2,6-dimethoxybenzoyl)(2,4,4-trimethylpentyl)phosphine oxide, etc. These compounds can be used individually or in combination.

[0078] Cationic polymerizable materials that may be used in this disclosure include, but are not limited to, materials containing epoxy groups and vinyl ether functional groups. These systems are photoinitiated with onium salt initiators such as triarylsulfonium salts and diaryliodonium salts.

[0079] In one embodiment, the thickness of the backing material of the tool structure is approximately 400, 250, 150, 100, 75, or 50 micrometers or less, for example, 30–225 micrometers, 50–200 micrometers, or 100–150 micrometers. In one embodiment, the trunk (above the backing material) has a maximum height of 5 mm, 3 mm, 1.5 mm, 1 mm, 500 micrometers, 400 micrometers, 300 micrometers, 200 micrometers, or 100 micrometers, and in one embodiment, has a minimum height of at least approximately 5 micrometers, 10 micrometers, 25 micrometers, 50 micrometers, 75 micrometers, 100 micrometers, 125 micrometers, 150 micrometers, 175 micrometers, or 200 micrometers. In one embodiment, the trunk has an aspect ratio (i.e., the ratio of height to width at its widest part) of at least approximately 2:1, 3:1, or 4:1.

[0080] The protrusion (measured at the widest part of the trunk) is 1 micrometer or larger, 2 micrometers or larger, 3 micrometers, 5 micrometers, 7 micrometers, 10 micrometers, 12 micrometers, 15 micrometers, 20 micrometers, 25 micrometers, 30 micrometers, 35 micrometers, 40 micrometers, 45 micrometers, 50 micrometers, 60 micrometers, 70 micrometers, 80 micrometers, 90 micrometers, 100 micrometers, 110 micrometers, 120 micrometers, The projection may have an average diameter of 120 micrometers, 140 micrometers, or 150 micrometers or more; and 500 micrometers or less, 475 micrometers, 450 micrometers, 425 micrometers, 400 micrometers, 375 micrometers, 350 micrometers, 325 micrometers, 300 micrometers, 275 micrometers, 250 micrometers, 225 micrometers, 200 micrometers, 190 micrometers, 180 micrometers, 170 micrometers, or 160 micrometers or less. In many embodiments, the projection has an average diameter of 1 micrometer to 500 micrometers, or 10 micrometers to 300 micrometers.

[0081] [Exemplary Embodiments] In a first embodiment, the disclosure provides a porous polymer film. The porous polymer film includes a) a first outer surface having a pattern arrangement of first pores having irregularly shaped peripheries; b) a second outer surface on the opposite side having a plurality of second pores; and c) a polymer matrix present between the first outer surface and the second outer surface. The polymer matrix defines a plurality of through-pores present between the first pores and the second pores.

[0082] In a second embodiment, the disclosure provides a porous polymer film according to the first embodiment, wherein the through-holes have an average diameter of 1 micrometer to 500 micrometers, or 10 micrometers to 300 micrometers.

[0083] In a third embodiment, the disclosure provides a porous polymer film according to the first or second embodiment, wherein the plurality of second pores have regularly shaped peripheries.

[0084] In a fourth embodiment, the disclosure provides a porous polymer film according to any one of the first to third embodiments, wherein the polymer matrix located adjacent to the through-holes is porous.

[0085] In a fifth embodiment, the disclosure provides a porous polymer film according to any one of the first to third embodiments, wherein the polymer matrix located adjacent to the through-holes is non-porous.

[0086] In a sixth embodiment, the disclosure provides a porous polymer film according to any one of the first to fifth embodiments, wherein the through-holes are isoporous.

[0087] In the seventh embodiment, the disclosure provides a porous polymer film according to any one of the first to sixth embodiments, wherein the thickness between the first outer surface and the second outer surface is 1 micrometer or more.

[0088] In the eighth embodiment, the disclosure provides a porous polymer film according to any of the first to seventh embodiments, wherein the through-holes have a density of 50 or more per square centimeter on the first outer surface.

[0089] In the ninth embodiment, the disclosure provides a porous polymer film according to any one of the first to eighth embodiments, wherein the polymer matrix comprises polyethersulfone, polypropylene, polysulfone, polyacrylonitrile, cellulose ester, polyimide, polyamide, poly(vinylidene fluoride), or poly(tetrafluoroethylene).

[0090] In a tenth exemplary embodiment, the present disclosure provides a porous polymer film according to any of the first to ninth exemplary embodiments, wherein the polymer matrix comprises polyethersulfone or amorphous nylon.

[0091] In an eleventh exemplary embodiment, the disclosure provides a porous polymer film according to any one of the first to tenth exemplary embodiments, wherein the first pores have an average area less than half the average area of ​​the second pores.

[0092] In a twelfth exemplary embodiment, the present disclosure provides a method comprising the steps of applying a casting solution to a tool structure having a main surface and a pattern arrangement of projections extending orthogonally from the main surface to form a layer of the casting solution. The casting solution comprises a polymer component and a solvent system. The method further comprises the steps of bringing the layer of casting solution into contact with a non-solvent fluid to solidify the polymer component and form a porous polymer film, and removing the porous polymer film from the tool structure, thereby providing a porous polymer film. The porous polymer film comprises: 1) a first outer surface having an irregularly shaped periphery not corresponding to the shape of the tops of a plurality of projections and having a pattern arrangement of first pores; 2) a second outer surface on the opposite side having a plurality of second pores; and 3) a polymer matrix present between the first outer surface and the second outer surface. The polymer matrix defines a plurality of through-pores present between the first pores and the second pores.

[0093] In a thirteenth exemplary embodiment, the disclosure provides a method of the twelfth exemplary embodiment, wherein the projection includes a trunk and a head, the trunk extending perpendicularly from the main surface of the tool structure, and the head positioned away from the main surface of the tool structure.

[0094] In a fourteenth exemplary embodiment, the disclosure provides a method according to the thirteenth exemplary embodiment, wherein the projection is T-shaped, nail-shaped, mushroom-shaped, or a combination thereof.

[0095] In a 15th exemplary embodiment, the disclosure provides a method according to a 13th or 14th exemplary embodiment, wherein the first hole has an average hole diameter smaller than the head of the projection.

[0096] In a sixteenth exemplary embodiment, the disclosure provides a method according to any twelfth to fourteenth exemplary embodiment, wherein the layer of casting solution has a thickness less than the height of the protrusion.

[0097] In a 17th exemplary embodiment, the Disclosure provides a method according to any 12th to 14th exemplary embodiment, wherein the layer of casting solution has a thickness equal to the height of the protrusion.

[0098] In the 18th exemplary embodiment, the disclosure provides a method according to any 12th to 15th exemplary embodiment, wherein the layer of casting solution has a thickness greater than the height of the protrusion.

[0099] In a 19th exemplary embodiment, the disclosure provides a method according to any 12th to 18th exemplary embodiment, wherein the casting solution has a solid content of 5% to 50% by weight.

[0100] In a 20th exemplary embodiment, the Disclosure provides a method according to any 12th to 18th exemplary embodiment, wherein the polymer component comprises polyethersulfone, polypropylene, polysulfone, polyacrylonitrile, cellulose ester, polyimide, polyamide, poly(vinylidene fluoride), or poly(tetrafluoroethylene).

[0101] In a 21st exemplary embodiment, the disclosure provides a method according to any 12th to 20th exemplary embodiment, wherein the polymer component comprises polyethersulfone or amorphous nylon, the solvent system comprises dimethyl sulfoxide, and the non-solvent fluid comprises water.

[0102] In a 22nd exemplary embodiment, the disclosure provides a method according to any 12th to 21st exemplary embodiment, wherein the tool structure is formed of polypropylene or a crosslinked (meth)acrylate polymer.

[0103] In a 23rd exemplary embodiment, the Disclosure provides a method according to any 12th to 22nd exemplary embodiment, wherein the projection has an average diameter of 1 micrometer to 500 micrometers, or 10 micrometers to 300 micrometers.

[0104] In a 24th exemplary embodiment, the disclosure provides a method according to any 12th to 23rd exemplary embodiment, wherein the porous polymer film is a porous polymer film described in any of the 1st to 11th exemplary embodiments.

[0105] The advantages and embodiments of the present invention are further illustrated by the following examples, but the specific materials and their quantities described in these examples, as well as other conditions and details, should not be construed as unduly limiting the invention. Unless otherwise specified, parts and percentages are by weight. [Examples]

[0106] Unless otherwise specified or as is clear from the context, all parts, percentages, ratios, etc., in the examples and other descriptions herein are on a weight basis.

[0107] For the film fabrication polymer, we used polyethersulfone (PES), commercially available from BASF (Wyandot, Michigan) under the trade name "ULTRASON E6020". As the solvent, we selected N-methylpyrrolidone (NMP), also available from BASF (Wyandot, Michigan). Deionized water was used as the non-solvent. 10% by weight of PES was dissolved in NMP using a speed mixer at room temperature and mixed until a homogeneous, clear solution was obtained. The solution was then allowed to stand overnight at 60°C to remove trapped air bubbles.

[0108] The structured surfaces used to fabricate the membrane were mechanical fastener strips made from an ethylene-propylene copolymer, available from Dow Chemical Company (Midland, Michigan) under the trade name "C700-35N," using the method described in U.S. Patent No. 5,845,375 (Miller et al.). These mechanical fastener strips were arranged alternately. The posts were conical in shape. The distal ends of the posts were deformed by a textured heated surface to form grooved caps, as disclosed in U.S. Patent No. 6,708,378 (Parellada et al.) or No. 5,868,987 (Kampfer et al.).

[0109] The film was prepared by casting a uniform PES solution onto the structured surface using a doctor blade, ensuring that the scraping action of the blade contacted the top of the cap and wiped away any excess PES solution present on the cap. The structured surface coated with the PES solution was immediately immersed in deionized water at 25°C. Upon immersion, the PES solution gradually solidified into an opaque film that remained attached to the structured surface. The solidified film was slowly peeled off the structured surface and stored in deionized water at 25°C until subsequent analysis. The structured surface had a height of 350 micrometers, allowing for the casting of the PES solution. Note that the initial casting thickness of the film depended on the height of the structured surface itself, suggesting that other structured surfaces with higher or lower heights may be useful for preparing films of different thicknesses.

[0110] SEM analysis was performed using a JEOL JSM-6510LV scanning electron microscope. After storing the film samples in a refrigerator for 24 hours, they were cut into small pieces, mounted in a sample holder, coated with platinum to impart conductivity, and then images were acquired. Some of the imaged samples are shown in Figures 2A and 2B above.

[0111] Foreseeable changes and modifications to the present invention will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The present invention should not be limited to the embodiments described herein for illustrative purposes.

Claims

1. A porous polymer film, a) A first outer surface having a pattern arrangement of first holes with irregularly shaped peripheries, b) A second outer surface on the opposite side having a plurality of second holes, c) A polymer matrix that exists between the first outer surface and the second outer surface, The polymer matrix is ​​a porous polymer film that defines a plurality of through-pores existing between the first pore and the second pore.

2. The porous polymer film according to claim 1, wherein the through-holes have an average diameter of 1 micrometer to 500 micrometers, or 10 micrometers to 300 micrometers.

3. The porous polymer film according to claim 1 or 2, wherein the plurality of second pores have regularly shaped peripheries.

4. The porous polymer film according to any one of claims 1 to 3, wherein the polymer matrix located adjacent to the through-hole is porous.

5. A porous polymer film according to any one of claims 1 to 3, wherein the polymer matrix located adjacent to the through-hole is non-porous.

6. The porous polymer film according to any one of claims 1 to 5, wherein the through-holes are isoporous.

7. The porous polymer film according to any one of claims 1 to 6, wherein the through holes have a density of 50 or more per square centimeter on the first outer surface.

8. The porous polymer film according to any one of claims 1 to 7, wherein the polymer matrix comprises polyethersulfone, polypropylene, polysulfone, polyacrylonitrile, cellulose ester, polyimide, polyamide, poly(vinylidene fluoride), or poly(tetrafluoroethylene).

9. The porous polymer film according to any one of claims 1 to 8, wherein the first pore has an average area less than half the average area of ​​the second pore.

10. A method comprising the following steps, A step of applying a casting solution to a tool structure having a main surface and a pattern arrangement of protrusions extending perpendicularly from the main surface to form a layer of the casting solution, wherein the casting solution comprises a polymer component and a solvent system. The process involves bringing the layer of the casting solution into contact with a non-solvent fluid to solidify the polymer component and form a porous polymer film. A step of removing the porous polymer film from the tool structure, This includes, and as a result, the following: 1) A first outer surface having a pattern arrangement of first holes having irregularly shaped peripheries that do not correspond to the shape of the upper parts of the plurality of protrusions, 2) A second outer surface on the opposite side having a plurality of second holes, 3) A polymer matrix that extends between the first outer surface and the second outer surface, wherein the polymer matrix defines a plurality of through-holes that extend between the first pore and the second pore. A method for providing a porous polymer film containing [a specific substance].

11. The method according to claim 10, wherein the projection includes a trunk and a head, the trunk extending perpendicularly from the main surface of the tool structure, and the head positioned away from the main surface of the tool structure.

12. The method according to claim 11, wherein the projection has a T-shape, a nail shape, a mushroom shape, or a combination thereof.

13. The method according to claim 11 or 12, wherein the first hole has an average hole diameter smaller than the head of the projection.

14. The method according to any one of claims 10 to 12, wherein the layer of casting solution has a thickness less than the height of the protrusion.

15. The method according to any one of claims 10 to 12, wherein the layer of casting solution has a thickness equal to the height of the protrusion.

16. The method according to any one of claims 10 to 12, wherein the layer of the casting solution has a thickness greater than the height of the protrusion.

17. The method according to any one of claims 10 to 16, wherein the casting solution has a solid content of 5% to 50% by weight.

18. The method according to any one of claims 10 to 17, wherein the tool structure is formed of polypropylene or a crosslinked (meth)acrylate polymer.

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