Composite material, method for producing same and use of same

Abstract

The present invention relates to a composite material comprising a polymer matrix and microparticles embedded in the polymer matrix, wherein the polymer matrix is at least partially gas-permeable and is not intrinsically electrically conductive, wherein the microparticles each comprise a structure of nanoparticles, and wherein the microparticles are covered completely by the polymer matrix. In addition, the present invention relates also to a method for producing the composite material and to the use of the composite material.

Description

[0001] FRAUNHOFER-GESELLSCHAFT...eV et al.

[0002] P149750PC00

[0003] Composite material, methods for its manufacture, and its use

[0004] The present invention relates to a composite material comprising a polymer matrix and microparticles embedded in the polymer matrix, wherein the polymer matrix is ​​at least partially gas-permeable and not intrinsically electrically conductive, wherein the microparticles each comprise a nanoparticle structure, and wherein the microparticles are completely covered by the polymer matrix. The present invention also relates to a method for producing the composite material and to the use of the composite material.

[0005] Supraparticles can be defined as all forms of complex particles composed of colloidally dispersed nanoparticles (optionally in combination with other molecular components) as the starting material. The supraparticles typically have sizes in the micrometer range (0.1–1000 pm). Supraparticles can thus be described as microparticles, each comprising a structure of nanoparticles. By combining individual nanoparticles into supraparticles, new and unique properties and thus functionalities can be achieved that are impossible to attain with individual nanoparticles or the bulk material.These new functionalities in supraparticles can be used for a wide variety of applications, such as air and water purification, agricultural systems for the targeted release ("delivery systems") of fertilizers or pesticides, energy storage and conversion, catalysis, the indication of environmental influences (as a sensor or recorder), the indication of gases (e.g. hydrogen), the marking of materials, as structural colors, or as a recycling aid.

[0006] Supraparticles are typically in powder form after their production. To make them usable for the aforementioned applications, it is often necessary to transform them into a composite material consisting of a supraparticle component and a matrix component. This transformation from supraparticle to macroscopic object (in one, two, or three dimensions, e.g., > 300–1000 pm) serves to enable the handling of the supraparticles by humans and / or machines, as well as to add further positive properties (not present at the supraparticle level) to the resulting object and / or to compensate for undesired supraparticle properties without diminishing essential, desired supraparticle properties.A particular focus is on enabling the interaction of supraparticles within the composite material with flowing media, especially gases or vapors (as required, for example, in gas indication or catalysis), while protecting them from other environmental influences such as mechanical stresses, temperature, UV or solvents, and permanently preventing the release of supraparticles or supraparticle building blocks.

[0007] In J. Reichstein, P. Groppe, N. Stockinger, C. Cuadrado Collados, M. Thommes, S. Wintzheimer, K. Mandel, "Safety Through Visibility: Tracing Hydrogen in Colors with Highly Customizable and Flexibly Applicable Supraparticle Additives," Adv. Mater. Technol. 2024, 2400441, hydrogen indicator supraparticles are integrated into a coating varnish applied to a polymer film. The varnish was synthesized by dissolving hydroxyethylcellulose (HEC) and polylactic acid (PLA) in a mass ratio of 5:3 in toluene (10 wt% solids content). In a typical experiment, 94 mg PLA and 156 mg HEC were dissolved in 2.5 g toluene under vigorous stirring for several days. Subsequently, approximately 20 mg of hydrogen indicator supraparticles were rapidly mixed with 50 mg of the coating varnish. This mixture was applied to a flexible polymer film using a pipette without any additional surface treatment.Toluene was then evaporated under ambient conditions over several hours. The resulting material composite consists of micrometer-sized supraparticles loosely bonded together by the PLA / HEC polymer lacquer. The resulting material composite retains its original functionality, namely the detection of hydrogen gas via a color change visible to the naked eye.

[0008] The supraparticles are only loosely bonded together by the PLA / HEC polymer lacquer and are therefore exposed to gases and other environmental influences. While this ensures hydrogen indication and good handling, it does not prevent, for example, the leaching of the indicator dye contained in the supraparticles upon contact with water and does not offer sufficient mechanical stability.

[0009] Based on this, the object of the present invention was to provide a composite material comprising a polymer matrix and microparticles comprising a structure of nanoparticles, wherein the composite material should, on the one hand, essentially retain the functionality of the microparticles and, on the other hand, better protect the microparticles from external influences.

[0010] This problem is solved with respect to a composite material having the features of claim 1 and with respect to a method for producing the composite material having the features of claim 8. Claim 15 relates to uses of the composite material according to the invention. The dependent claims represent advantageous embodiments.

[0011] According to the invention, a composite material is thus provided which comprises a polymer matrix and microparticles embedded in the polymer matrix, wherein the polymer matrix is ​​at least partially gas-permeable and not intrinsically electrically conductive (i.e., either extrinsically electrically conductive or not electrically conductive at all), wherein the microparticles each comprise a structure of (colloidally dispersed) nanoparticles, and wherein the microparticles are completely covered by the polymer matrix.

[0012] The microparticles, each comprising a structure of nanoparticles, can also be referred to as supraparticles. The structure of nanoparticles can also be referred to as a particle superstructure. In addition to the structure of (colloidally dispersed) nanoparticles, the microparticles can also comprise further components, preferably further molecular components, which are preferably embedded in the structure of nanoparticles.

[0013] It is essential that the microparticles each comprise a structure of nanoparticles (i.e., the nanoparticles exist as a structure). The microparticles do not merely comprise a random accumulation of nanoparticles without structure. Only microparticles that each comprise a structure of nanoparticles can also be referred to as supraparticles. Therefore, the microparticles used in the present invention differ from randomly agglomerated nanoparticles (such as carbon black or pyrogenic silicon dioxide) and, compared to these, also exhibit additional functionality (such as coupling, emergence, and / or colocalization). Randomly agglomerated nanoparticles, on the other hand, are not supraparticles, since they possess no structure whatsoever, but are merely an accumulation of randomly aggregated nanoparticles without any structure. Thus, the microparticles are not randomly agglomerated nanoparticles (or...random agglomerates of nanoparticles), since randomly agglomerated nanoparticles do not comprise a structure made up of nanoparticles.

[0014] The structure of nanoparticles can arise, for example, from a consistent structural motif prevalent in the microparticles (or supraparticles), such as crystal packing, fractal dimension, nearest-neighbor connectivity, and / or a defined average size and / or shape, which leads to the creation of additional functionality, e.g., in the form of coupling, emergence, and / or colocalization. Coupling describes the strong interaction between electrons in nanoparticles within a supraparticle due to their close proximity, while emergence arises more from a specific structure within a supraparticle than from the intrinsic properties of the individual building blocks.Colocalization means that different nanoparticles with varying properties within a supraparticle form a distinguishable common entity with combined or superimposed properties that can be moved, removed, concentrated, and observed individually. A consistent structural motif can be understood as the recurring relationship between the particles that make up the supraparticle. Typical examples include the number and distance of nearest neighbors, the positions of particles in a crystal structure, or the orientation of anisotropic particles within the supraparticle. For more complex supraparticles, additional motifs include the proximity or numerical ratio of different particle types and their preferred positions, for example, in a core-shell structure.

[0015] For example, the microparticles (or supraparticles) exhibit a consistent structural motif (of the nanoparticles) (i.e., a recurring relationship between the nanoparticles), which is selected, for example, from the group consisting of crystal packing; fractal dimension; (essentially) the same connectivity to the nearest neighbor (or nearest neighboring nanoparticle), e.g., the same number of nearest neighbors (or nearest neighboring nanoparticles) and / or (essentially) the same distance to the nearest neighbor (or nearest neighboring nanoparticle); (essentially) the same (defined) average size and / or shape (of the nanoparticles); the same orientation of anisotropic particles (or nanoparticles) within the supraparticle; recurring neighborhood of different particle types (or nanoparticle types); and the same numerical ratios of different particle types (or nanoparticles).Nanoparticle types); specific positions of certain particle types (or nanoparticle types), e.g. in a core-shell structure; and combinations thereof.

[0016] For example, the microparticles could be supraparticles for the optimal indication of hydrogen, as described, for instance, in WO 2023 / 066775 Al. In this case, the microparticles could contain, as further molecular components embedded in the nanoparticle structure, at least one catalytically active substance for catalyzing hydrogen dissociation and at least one redox dye.

[0017] The microparticles according to the present invention have a diameter in the range of 0.1 pm to 1000 pm, preferably in the range of 0.5 pm to 250 pm, and particularly preferably in the range of 1 pm to 50 pm. The diameter of the microparticles can be determined, for example, by laser diffraction or scanning electron microscopy.

[0018] The nanoparticles according to the present invention have a diameter in the range of 0.5 nm to 1000 nm, preferably in the range of 0.7 nm to 500 nm, particularly preferably in the range of 0.8 nm to 490 nm, and particularly preferably in the range of 1 nm to 100 nm. The diameter of the nanoparticles can be determined, for example, by dynamic light scattering, transmission electron microscopy, or scanning electron microscopy.

[0019] The polymer matrix contained in the composite material according to the invention is at least partially gas-permeable (regardless of the polymer matrix layer thickness). This can be demonstrated, for example, by measuring the gas permeability, the so-called barrier effects, according to standards such as ASTM D 1434:2023, DIN EN ISO 2556:2001-01, or ISO 15105-1:2007-10. These measurements can be carried out, for example, using H₂ or O₂ as the gas and / or with a polymer matrix layer thickness of 130 pm or 3 mm. The following measuring device, for example, can be used for these measurements: Pubtester GTR-G3 (Gas Permeability Meter GTR-G3 (Difference Pressure Method - 3 Samples)).

[0020] In the composite material according to the invention, the microparticles are completely covered by the polymer matrix. As a result, the microparticles are better protected against external influences (such as UV light, elevated temperatures, solvents, and / or mechanical stresses). At the same time, the polymer matrix is ​​at least partially gas-permeable, which means that the microparticles remain accessible to and can interact with certain desired target media, such as gases and / or vapors (e.g., hydrogen and / or water vapor), so that the functionality of the microparticles is essentially maintained. The fact that the polymer matrix is ​​at least partially gas-permeable can be achieved, for example, by an adjustable open crosslinking of the polymer matrix. For example, a suitable open crosslinking of the polymer matrix can be achieved by varying the chain lengths and / or degrees of crosslinking of the polymers used.Such a setting of a suitable open-mesh cross-linking to achieve at least partial gas permeability of the polymer matrix is ​​possible for a person skilled in the art within the scope of their expertise. Alternatively or additionally, the polymer matrix can, for example, also have suitable pores to achieve at least partial gas permeability.

[0021] The polymer matrix contained in the composite material according to the invention is not intrinsically electrically conductive, i.e., the polymer matrix consists of one or more non-intrinsically electrically conductive polymers. Intrinsically electrically conductive polymers are polymers that inherently possess electrical conductivity. The electrical conductivity of the polymer is achieved through conjugated double bonds or a conjugated double bond system. Polymers that are conductive only through electrically conductive fillers, such as aluminum flakes or carbon black, are, on the other hand, referred to as extrinsically electrically conductive polymers. The non-intrinsically electrically conductive polymer matrix contained in the composite material according to the invention is therefore understood to be a polymer matrix that (or whose polymer(s)) does not have any conjugated double bonds or a conjugated double bond system (and thus is inherently conductive).(without the use of electrically conductive fillers - exhibits no electrical conductivity). The polymer matrix contained in the composite material according to the invention can either be extrinsically electrically conductive or not electrically conductive at all.

[0022] Because the polymer matrix is ​​not intrinsically electrically conductive, any potential charge transfer can be avoided, thus preventing the polymer matrix from acting as an ignition source. Consequently, the composite material is advantageously suitable for use in potentially explosive atmospheres. Furthermore, the non-intrinsically electrically conductive polymer matrix makes the composite material very cost-effective.

[0023] The polymer matrix ensures the complete encapsulation of microparticles or supraparticles, protecting them from unwanted external influences such as UV light, elevated temperatures, solvents, or mechanical stress, and permanently fixing the microparticles or supraparticles and their components. At the same time, this matrix allows for defined accessibility of the supraparticles to certain media, such as gases. The composite material can be applied as a fiber, layer, coating, printed / printable body, pellet, monolith, or foam.

[0024] The composite material according to the invention represents, in comparison to previously known approaches, the only solution for completely enclosing supraparticles, keeping them accessible to specific media, and simultaneously shielding them at least partially against further external environmental influences. In this process, the supraparticles can be completely and permanently encapsulated by the matrix material. Furthermore, it is possible that during the production of the composite material, i.e., the incorporation of the supraparticles into the matrix precursors, no penetration of solvent / matrix material into the pores / pore network of the supraparticle occurs, for example, due to the absence of solvents in precursor mixtures as binders, or the low proportion of solvents in the overall formulation of binder solutions, as well as the highly volatile nature of the solvents used.This prevents the pore network from becoming clogged by matrix material and also minimizes the migration of functional molecules out of the supraparticle network. The supraparticles in the composite material can continue to interact with desired target media, such as gases and / or vapors—for example, hydrogen and / or water vapor. Furthermore, it is possible to optimize the composite material so that the supraparticles can still interact with specific desired liquids. This can be achieved by selecting the polymer matrix accordingly, ensuring suitable permeability for the desired liquid. Alternatively, the polymer matrix can be selected to be non-permeable to liquids.In principle, the migration rate of the target media can also be specifically adjusted via the matrix properties, such as material composition, degree of polymer cross-linking, thickness of the matrix layer (which encloses the supraparticles), pore distribution, or porosity. Furthermore, the supraparticles in the composite material are shielded to a certain extent (adjustable through the matrix properties) from unwanted external environmental influences, such as UV light, elevated temperatures, solvents, and mechanical stress.

[0025] A preferred embodiment of the composite material according to the invention is characterized in that the polymer matrix contains or consists of at least one polymer selected from the group consisting of polysiloxanes, polymethyl methacrylate, inorganic-organic hybrid polymers, polyvinylpyrrolidone, hydroxyethylcellulose, polylactides, and mixtures thereof.

[0026] The inorganic-organic hybrid polymers are preferably inorganic-organic hybrid polymers as described in WO 2010 / 069958 Al or WO 2013 / 092433 Al. For example, the inorganic-organic hybrid polymers could be ORMOCERe®.

[0027] According to a further preferred embodiment of the composite material according to the invention, the nanoparticles are selected from the group consisting of metal nanoparticles; metal oxide nanoparticles; semi-metal oxide nanoparticles, preferably e.g. SiO2 nanoparticles; polymer nanoparticles; and mixtures thereof.

[0028] Another preferred embodiment of the composite material according to the invention is characterized in that the polymer matrix is ​​not electrically conductive (i.e., it is neither intrinsically electrically conductive nor extrinsically electrically conductive).

[0029] Another preferred embodiment of the composite material according to the invention is characterized in that the polymer matrix is ​​in the form of at least one layer with a layer thickness in the range of 0.2 pm to 10 mm, preferably in the range of 1 pm to 1 mm, particularly preferably in the range of 5 pm to 500 pm (whereby the at least one polymer matrix layer is at least partially gas-permeable).

[0030] Another preferred embodiment of the composite material according to the invention is characterized in that the polymer matrix has a gas permeability (or gas permeability rate) of at least 1,000 cm⁻¹. 3 / (m 2 • d • bar), preferably at least 5,000 cm² 3 / (m 2 • d • bar), particularly preferably at least 10,000 cm³ 3 / (m 2 • d • bar), most preferably at least 20,000 cm² 3 / (m 2• d • bar), exhibits (e.g., determined using H2 or O2 as the gas). For example, the polymer matrix can have a gas permeability (or gas permeability rate) for H2 of at least 20,000 cm². 3 / (m 2 • d • bar), preferably at least 30,000 cm³ 3 / (m 2 • d • bar), particularly preferably at least 40,000 cm³ 3 / (m 2 • d • bar), and / or a gas permeability (or gas permeability rate) for O2 of at least 100,000 cm³ 3 / (m 2 • d • bar), preferably at least 120,000 cm³ 3 / (m 2 • d • bar), particularly preferably at least 140,000 cm³ 3 / (m 2 • d • bar), exhibit.

[0031] Gas permeability can be determined, for example, by measuring the so-called barrier effect according to standards such as ASTM D 1434:2023, DIN EN ISO 2556:2001-01, or ISO 15105-1:2007-10. This measurement can be performed, for instance, with a polymer matrix layer thickness of 130 pm. A suitable instrument for determining gas permeability is, for example, the Pubtester GTR-G3 (Gas Permeability Meter GTR-G3 (Difference Pressure Method - 3 Samples)).

[0032] For example, the polymer matrix contained in the composite material according to the invention (regardless of the layer thickness of the polymer matrix) can be at least partially gas-permeable to any gas, in particular to gases selected from the group consisting of H2, O2, CO, NO X , CO2, methane, ethane, propane, butane, alcohols (in the gas phase), formates, NH3, sarin, and mixtures or combinations thereof.

[0033] According to a further embodiment of the composite material according to the invention, the composite material comprises at least one (different from the polymer matrix) support element, wherein at least one layer of the polymer matrix is ​​arranged on each support element. The composite material can comprise one support element on which at least one layer of the polymer matrix is ​​arranged, or the composite material can comprise several support elements, wherein at least one layer of the polymer matrix is ​​arranged on each of the several support elements.

[0034] Furthermore, it is preferred that the at least one support element contains or consists of a material selected from the group consisting of ceramics; metals; alloys, preferably steel; metal oxides, preferably aluminum oxide; plastics or polymers; glass, preferably soda-lime glass; wood; and combinations thereof.

[0035] Preferably, the composite material consists of the polymer matrix and the microparticles, and optionally the at least one carrier element.

[0036] It is possible that the composite material does not have a support element (in addition to the polymer matrix). This can be the case, in particular, if the polymer matrix is ​​so mechanically stable that no such support element is required.

[0037] Preferably, the composite material can be in the form of a fiber, layer, coating, printed / printable body, pellet or monolith or foam and / or applied in that form.

[0038] Another preferred embodiment of the composite material according to the invention is characterized in that the composite material is formed in the form of at least one composite particle, wherein the at least one carrier element is at least one carrier particle and wherein at least one layer of the polymer matrix is ​​arranged on each carrier particle. Preferably, the composite material is formed in the form of several composite particles, wherein the composite material comprises several carrier elements, which are several carrier particles, and wherein at least one layer of the polymer matrix is ​​arranged on each of the carrier particles. Particularly preferably, the composite material, which is formed in the form of several composite particles, can be in the form of a powder or granules.

[0039] The at least one composite particle can also be called a suprabead.

[0040] Furthermore, it is preferred that

[0041] - that at least one composite particle (each) has a diameter in the range of 0.1 mm to 25 mm, preferably in the range of 0.3 mm to 10 mm, particularly preferably in the range of 0.5 mm to 1.5 mm, and / or

[0042] - that at least one carrier particle is essentially spherical, essentially droplet-shaped, essentially ellipsoidal or essentially egg-shaped, and / or

[0043] - that at least one carrier particle contains or consists of a material selected from the group consisting of ceramics; metals; alloys, preferably steel; metal oxides, preferably aluminum oxide; plastics; glass, preferably soda-lime glass; wood; and combinations thereof, and / or

[0044] - that at least one carrier particle has a diameter in the range of 0.1 mm to 25 mm, preferably from 0.3 mm to 10 mm, particularly preferably from 0.5 mm to 1.5 mm, and / or that at least one polymer matrix layer has a layer thickness in the range of 0.2 pm to 100 pm, preferably in the range of 1 pm to 50 pm, particularly preferably in the range of 5 pm to 25 pm, and / or that at least one polymer matrix with the microparticles embedded therein contains 50.0 to 99.9 wt.%, preferably 75.0 to 99.5 wt.%, particularly preferably 90.0 to 99.0 wt.%, of the microparticles, based on the total weight of the at least one polymer matrix with the microparticles embedded therein, and / or

[0045] - containing at least one polymer matrix with the microparticles embedded therein 0.1 to 50.0 wt.%, preferably 0.5 to 25.0 wt.%, particularly preferably 1.0 to 10.0 wt.%, of the at least one polymer, based on the total weight of the at least one polymer matrix with the microparticles embedded therein.

[0046] The diameter of the at least one composite particle and / or the at least one carrier particle can be determined, for example, by scanning electron microscopy or other light microscopy or laser scanning microscopy.

[0047] The thickness of the at least one polymer matrix layer can be determined, for example, by means of cross-sectional preparation and scanning electron microscopy.

[0048] Another preferred embodiment of the composite material according to the invention is characterized in that the at least one support element is designed in the form of at least one planar support element, preferably in the form of a film, a plate or a disc, or in the form of at least one three-dimensional support element, which preferably has an extent of more than 2.5 cm, preferably more than 3 cm, in at least one spatial direction.

[0049] Furthermore, it is preferred that

[0050] - that at least one planar support element contains or consists of a material selected from the group consisting of glass, metals, alloys, polymers, and combinations thereof, and / or

[0051] - the at least one three-dimensional support element contains or consists of a material selected from the group consisting of ceramics, metals, alloys, metal oxides, plastics, glass, wood, and combinations thereof, and / or the polymer matrix is ​​arranged in the form of at least one layer on the at least one (planar or three-dimensional) support element, which has a layer thickness in the range of 100 pm to 10 mm, preferably in the range of 150 pm to 1 mm, particularly preferably in the range of 200 pm to 500 pm, and / or the at least one polymer matrix with the microparticles embedded therein contains 0.1 to 75.0 wt.%, preferably 1.0 to 50.0 wt.%, particularly preferably 5.0 to 30.0 wt.% of the microparticles, based on the total weight of the at least one polymer matrix with the microparticles embedded therein, and / or

[0052] - containing at least one polymer matrix with the microparticles embedded therein 25.0 to 99.9 wt.%, preferably 50.0 to 99.0 wt.%, particularly preferably 70.0 to 95.0 wt.%, of the at least one polymer, based on the total weight of the at least one polymer matrix with the microparticles embedded therein.

[0053] The thickness of at least one layer of the polymer matrix can be determined, for example, using a layer thickness gauge, laser scanning microscopy or scanning electron microscopy.

[0054] The present invention further relates to a method for producing the composite material according to the invention, in which a) a liquid starting material for an at least partially gas-permeable and non-intrinsically electrically conductive polymer matrix is ​​applied layer by layer (i.e., in the form of at least one layer) to at least one support element, and b) at least one curing process is carried out in which the polymer matrix is ​​formed from the applied starting material, wherein microparticles, each comprising a structure of nanoparticles, are introduced into the starting material before step a) or between step a) and step b), and wherein, when step b) begins, the microparticles are completely covered by the starting material.

[0055] The microparticles can be introduced into the starting material before or after its application (to the at least one carrier element). Thus, two fundamental variants are available for producing the composite material according to the invention.

[0056] According to the first manufacturing variant, before step a), the microparticles, each comprising a structure of nanoparticles, are incorporated into the starting material. Subsequently, in step a), the starting material with the incorporated microparticles is applied to the at least one support element. Finally, in step b), at least one curing process takes place, during which the polymer matrix is ​​formed from the applied starting material.

[0057] According to the second manufacturing variant, in step a), the liquid starting material is first applied to at least one support element, followed by the introduction of microparticles, each comprising a structure of nanoparticles, into the applied starting material between step a) and step b). Finally, in step b), at least one curing process takes place, during which the polymer matrix is ​​formed from the applied starting material.

[0058] By ensuring that the microparticles are completely covered by the starting material when step b) begins, it can be achieved that the microparticles in the produced composite material are completely covered by the polymer matrix. This complete coverage of the microparticles when step b) begins can be achieved, for example, by appropriately introducing the microparticles into the starting material, such as by mixing, preferably (completely) dispersing, the microparticles with the at least one starting material before step a), or by mixing, preferably (completely) dispersing, the microparticles with the at least one carrier element onto which the starting material is applied between step a) and step b).By mixing, preferably (completely dispersing) the corresponding components, it can be achieved that the microparticles are completely surrounded by the starting material for the polymer matrix.

[0059] Preferably, the microparticles, each comprising a structure of nanoparticles, are introduced into the starting material before step a) or between step a) and step b) by mixing, preferably (completely) dispersing, the microparticles with the starting material before step a) or between step a) and step b). In other words, the microparticles are preferably introduced into the starting material by mixing, preferably (completely) dispersing, the microparticles with the at least one starting material before step a), or by mixing, preferably (completely) dispersing, the microparticles with the at least one carrier element onto which the starting material is applied between step a) and step b).

[0060] A preferred embodiment of the process according to the invention is characterized in that the liquid starting material comprises at least one solvent and at least one polymer selected from the group consisting of polysiloxanes, polymethyl methacrylate, inorganic-organic hybrid polymers, polyvinylpyrrolidone, hydroxyethylcellulose, polylactides, and mixtures thereof, or at least one precursor, preferably in the form of monomers and / or oligomers, from which at least one polymer is formed during the at least one curing process, preferably by crosslinking, which is selected from the group consisting of polysiloxanes, polymethyl methacrylate, inorganic-organic hybrid polymers, polyvinylpyrrolidone, hydroxyethylcellulose, polylactides, and mixtures thereof.

[0061] According to a further preferred embodiment of the method according to the invention, the at least one curing process takes place at a temperature in the range of 5 °C to 40 °C, preferably in the range of 10 °C to 30 °C, particularly preferably at room temperature, and / or under exclusion of light.

[0062] If necessary, a foaming agent can be added to generate pores in the matrix and thus adjust the penetration of the matrix layer for target media. An inhibitor, such as the volatile "Inhibitor 600" (Evonik AG), can also be added to suppress the curing of the binder, whether as a pure matrix material or as a premix already containing supraparticles. This allows for its use in other applications, such as printing ink or as a starting material for 3D printing.Another preferred embodiment of the method according to the invention is characterized in that the at least one carrier element is at least one carrier particle, wherein in step a) the liquid starting material is applied layer by layer to the at least one carrier particle by mixing the liquid starting material with the at least one carrier particle, and wherein the microparticles are introduced into the at least one applied starting material between step a) and step b) by mixing the microparticles with the at least one carrier particle onto which the starting material is applied.

[0063] Furthermore, it is preferred that

[0064] - the mixing of the liquid starting material with the at least one carrier element takes place for a duration of 0.1 to 15 minutes, preferably 1 to 2.5 minutes, and / or

[0065] - the mixing of the microparticles with the at least one carrier element onto which the starting material is applied takes place for a duration of 0.1 to 15 minutes, preferably 0.5 to 2.5 minutes.

[0066] Another preferred embodiment of the method according to the invention is characterized in that the at least one support element is designed in the form of at least one planar support element, preferably in the form of a film, a plate or a disc, or in the form of at least one three-dimensional support element, which preferably has an extent of more than 2.5 cm in at least one spatial direction, wherein the microparticles are introduced into the at least one starting material before step a) by mixing the microparticles with the at least one starting material, and wherein in step a) the liquid starting material into which the microparticles have been introduced is applied to the at least one (planar or three-dimensional) support element by means of at least one coating process.

[0067] Furthermore, it is preferred that

[0068] - the mixing of the microparticles with the at least one starting material takes place for a duration of 0.1 to 15 minutes, preferably 1 to 2.5 minutes, and / or

[0069] - where at least one coating process is selected from the group consisting of doctor blade coating, centrifugal coating, dip coating, spray coating, brushing, printing, and combinations thereof, and / or after step b) the polymer matrix is ​​separated from the at least one carrier element.

[0070] Furthermore, the present invention also relates to the use of the composite material according to the invention for air and water purification, in agricultural systems for the targeted release (“delivery systems”) of fertilizers or pesticides, for energy storage and conversion, for catalysis, for the indication of environmental influences (as a sensor or recorder), for the indication of gases, e.g. hydrogen, for the marking of materials, as structural colors, as a recycling aid.

[0071] A preferred embodiment of the invention consists in applying a liquid precursor mixture or coating solution (hereinafter referred to as the binder in its liquid state) to a substrate material, and subsequently mixing this wetted substrate material with supraparticle powder. This results in complete wetting of the outer surface of the supraparticles and, after curing, completely encapsulates the supraparticles and fixes them to the surface of the substrate material. The cured binder is hereinafter referred to as the matrix. The substrate material can have the form of, for example, spheres, drops, or sphere-like shapes, preferably spheres, with diameters of 0.3 to 10.0 mm, more preferably 0.5 to 1.5 mm, and / or can consist of materials such as ceramics, metals, metal oxides, plastics, glass, wood, preferably aluminum oxide, steel, or soda-lime glass with varying surface roughness and porosity.The precursor mixture or coating solution can consist of, for example, monomers, oligomers, polymers, or a mixture thereof as organic, inorganic, or hybrid variants of varying chain lengths and reactivities with different solids content between 5 and 100%, preferably additively crosslinking siloxanes (100% solids content), as well as ORMOCERe® or plastics (such as PMMA). The mixing time of the carrier material and binder can be 0.1–15 minutes, preferably 1–2.5 minutes. The mixing time of the wetted carrier material with the supraparticles can be 0.1–15 minutes, preferably 0.5–2.5 minutes. By adjusting the binder, crosslinking at low temperatures, such as room temperature, is possible, which allows the use of supraparticles with thermally labile components, such as organic dyes. The use of supraparticles with regard to their properties, such as...Size, morphology, or functionality is not restricted, and all variants of this material class can be used. The different diameters of the carrier materials with varying densities result in formulations with widely varying weight fractions. Typical weight fractions for formulations range from 20–99.8% carrier material, 0.1–80% binder, and at least 0.05% supraparticles (which can be used in a large excess). The liquid nature of the binder and its adjustable, slow crosslinking at low temperatures ensure that the binder has sufficient time to completely coat all particles. The absence of solvents in precursor mixtures used as binders, or the low solvent content in the overall formulation of binder solutions, along with the highly volatile nature of the solvents used, prevents penetration into the pores of the supraparticles.The adjustable, open-mesh structure of the matrix allows gases to pass through the matrix layer. However, the matrix layer can shield against solvents such as water and protects against mechanical influences due to its properties, such as flexibility, which contributes to the dispersion of applied forces over a wide area. If necessary, a foaming agent can be added to generate pores in the matrix and thus adjust the penetration of the matrix layer for target media. The addition of inhibitors, such as the volatile "Inhibitor 600" (Evonik AG), can suppress the curing of the binder, either as pure matrix material or as a premix already containing superparticles, thus enabling its use in further applications, such as printing ink.The resulting macroscopic composite objects consist of cores covered with a thin layer of matrix in which supraparticles are completely embedded. The matrix binds the supraparticles to the carrier spheres, maintains the accessibility of the supraparticles to certain media such as gases, but protects the supraparticles from other environmental influences such as solvents or mechanical stress.

[0072] Another preferred embodiment of the invention consists of producing a coating solution from matrix material and supraparticles and applying it to a substrate. The supraparticles are completely dispersed in the matrix material (solvent + coating solution) so that they are entirely surrounded by it. The matrix material can consist of, for example, monomers, oligomers, polymers, or mixtures thereof as organic, inorganic, or hybrid variants of varying chain lengths and reactivities with different solids content between 5 and 100%, preferably additively crosslinking siloxanes (100% solids content), as well as ORMOCERe® or plastics (such as PMMA), and optionally one or more solvents. The coating solution can be applied by doctor blades, centrifugal coating, dip coating, spray coating, brushing, or printing.During the curing process, a layer forms in which the superparticles are completely encapsulated, yet the layer remains permeable to gases, for example. The coating can be applied to two-dimensional structures such as glass, metal, and flexible (polymer-based) films, as well as to three-dimensional objects. The mixing time of the superparticles and matrix material can range from 0.1 to 15 minutes, preferably 1 to 2.5 minutes. By adjusting the binder, crosslinking at low temperatures, such as room temperature, is possible, allowing the use of superparticles with thermally labile components such as organic dyes. The application of superparticles is not limited by their properties, such as size, morphology, or functionality, and all variants of this material class can be used.The varying diameters of the carrier materials with their different densities result in formulations with highly variable weight fractions. The adjustable, open-mesh crosslinking of the matrix allows gases to pass through the matrix layer. However, the matrix layer can shield against solvents such as water and protects against mechanical influences due to its properties, such as flexibility, which contribute to the dispersion of applied forces over a wide area. If necessary, a foaming agent can be added to generate pores in the matrix and thus adjust the penetration of the matrix layer for target media. The addition of inhibitors, such as the volatile "Inhibitor 600" (Evonik AG), can suppress the curing of the binder, either as pure matrix material or as a premix already containing superparticles, thus enabling its use in further applications, such as...It can be used as printing ink or as a starting material for 3D printing.

[0073] The present invention is explained in more detail with reference to the following figures and examples, without limiting the invention to the parameters specifically illustrated.

[0074] The right-hand section of Fig. 1 schematically illustrates an exemplary variant of the composite material according to the invention. Here, the composite material according to the invention is in the form of one or more composite particles, with only one such composite particle being shown in the right-hand illustration of Fig. 1. The composite particle shown comprises a carrier element, which is a carrier particle 1. A layer of a polymer matrix 2, which is at least partially gas-permeable and not intrinsically electrically conductive, is arranged on the carrier particle. Microparticles 3, each comprising a structure of nanoparticles 4, are embedded in the polymer matrix 2. The microparticles 3 are completely covered by the polymer matrix 2. The composite particle has a diameter in the millimeter range, as indicated by the lower scale in Fig. 1.

[0075] In the central section of Fig. 1, one of the microparticles 3 contained in the exemplary composite particle is shown schematically in enlarged form. The microparticle comprises a structure of nanoparticles 4. The microparticle 3 has a diameter in the micrometer range, as indicated by the lower scale in Fig. 1.

[0076] In the left section of Fig. 1, a single nanoparticle 4 contained in the microparticle 3 of the exemplary composite particle is shown schematically in enlarged form. The nanoparticle 4 has a diameter in the nanometer range, as indicated by the lower scale in Fig. 1. Exemplary embodiment 1: Matrix system polydimethylsiloxane, hydrogen indicator supraparticle, applied to a carrier sphere

[0077] The preparation of the precursor formulation used as the starting material for the polymer matrix is ​​carried out by weighing the components to be crosslinked into a polypropylene vessel suitable for speed mixers, with a perforated lid for pressure equalization during vacuum treatment. The components are the divinyl-terminated polydimethylsiloxane "Polymer VS 100000" and the trimethylsilyl-terminated dimethylsiloxane-methylhydrogensiloxane copolymer "Crosslinker 120", which are weighed out in a functional group ratio of 1.0:1.0. 20 mg of a catalyst solution (consisting of 90% POWERSIL® FLUID TR 50 and 10% of a platinum-based catalyst) are added.

[0078] Cyclovinylmethylsiloxane complex (cyclic methylvinylsiloxane with 3-3.5% Pt) was weighed onto 10 g of precursor mixture. Mixing was carried out using a SpeedMixer DAC 400.1VAC-P (Hauschild GmbH & Co. KG) and a PC 8 / RC 6 vacuum pump (Vacuubrand GmbH+Co KG) for one minute at 2500 revolutions per minute and 100% vacuum.

[0079] 4.0 g of purified and dry 99.5% aluminum oxide spheres with a diameter of 1 mm “72211” (Mühlmeier GmbH & Co. KG) are mixed with 120 mg of precursor mixture for 2 minutes in a cylindrical Teflon vessel with an inner diameter of 20 mm. 360 mg of supraparticles are weighed out and stirred for 30 seconds. The supraparticles were prepared according to embodiment 1 of WO 2023 / 066775 Al. Crosslinking takes place overnight at room temperature. Unfixed supraparticles are removed by sieving through a 125 pm nylon sieve using compressed air.

[0080] The resulting macroscopic composite objects consist of 1 mm thick aluminum oxide carrier spheres covered by a thin layer of superparticles (without a specific arrangement). The entire surface of the superparticles is covered by the silicone matrix, which bonds the superparticles to the core. The silicone matrix allows access to the superparticles for certain media, such as gases, while protecting them from other environmental influences, such as solvents or mechanical stress. Example 2: Matrix system polymethyl methacrylate, hydrogen indicator superparticles, applied as a layer

[0081] The matrix solution is prepared by weighing out the polymer (PMMA) and dissolving it in toluene (stirring at 300 rpm for 24 hours) to achieve a solids concentration of 30 wt.%. The supraparticles are then stirred in, resulting in a matrix solution containing 10 wt.% supraparticles. The supraparticles were prepared according to embodiment 1 of WO 2023 / 066775 Al.

[0082] Using a slitting blade, 500 µm thick layers are applied to a substrate (e.g., glass, polyolefin (PO) or polyethylene terephthalate (PET) film). The solvent is then allowed to evaporate overnight at room temperature and in the absence of light, resulting in a stable polymer film. Once cured, the polymer film can be removed from the substrate (e.g., PO, PET) to form a self-supporting film, or it can remain on the substrate, such as the flexible PET film. Applied to glass, the layer can be suspended at particularly leak-prone locations, and a color change can be observed through the glass. The self-supporting film or the film adhering to the PET film can be rolled directly around pipes to pinpoint leaks.

[0083] The resulting polymer film contains supraparticles that are completely incorporated into the matrix, but still has accessibility of the supraparticles to certain media, such as gases.

Claims

FRAUNHOFER-GESELLSCHAFT...eV et al. P149750PC00 Patent claims 1. Composite material comprising a polymer matrix and microparticles embedded in the polymer matrix, wherein the polymer matrix is ​​at least partially gas-permeable and not intrinsically electrically conductive, wherein the microparticles each comprise a structure of nanoparticles, and wherein the microparticles are completely covered by the polymer matrix.

2. Composite material according to the preceding claim, characterized in that the polymer matrix contains or consists of at least one polymer selected from the group consisting of polysiloxanes, polymethyl methacrylate, inorganic-organic hybrid polymers, polyvinylpyrrolidone, hydroxyethylcellulose, polylactides, and mixtures thereof.

3. Composite material according to one of the preceding claims, characterized in that the composite material comprises at least one support element, wherein at least one layer of the polymer matrix is ​​arranged on each support element.

4. Composite material according to claim 3, characterized in that the composite material is formed in the form of at least one composite particle, wherein the at least one carrier element is at least one carrier particle and wherein at least one layer of the polymer matrix is ​​arranged on each carrier particle.

5. Composite material according to claim 4, characterized in that the at least one composite particle has a diameter in the range of 0.1 mm to 25 mm, preferably in the range of 0.3 mm to 10 mm, particularly preferably in the range of 0.5 mm to 1.5 mm, and / or the at least one carrier particle is substantially spherical, substantially drop-shaped, substantially ellipsoidal or substantially egg-shaped, and / or the at least one carrier particle contains or consists of a material selected from the group consisting of ceramics; metals; alloys, preferably steel; metal oxides, preferably aluminum oxide; plastics; glass, preferably soda-lime glass; wood; and combinations thereof, and / or the at least one carrier particle has a diameter in the range of 0.1 mm to 25 mm, preferably from 0.3 mm to 10 mm, particularly preferably from 0.5 mm to 1.5 mm, and the at least one polymer matrix layer has a layer thickness in the range of 0.2 pm to 100 pm, preferably in the range of 1 pm to 50 pm, particularly preferably in the range of 5 pm to 25 pm.

6. Composite material according to claim 3, characterized in that the at least one support element is formed in the form of at least one planar support element, preferably in the form of a film, a plate or a disc, or in the form of at least one three-dimensional support element, which preferably has an extent of more than 2.5 cm in at least one spatial direction.

7. Composite material according to claim 6, characterized in that the at least one planar support element contains or consists of a material selected from the group consisting of glass, metals, alloys, polymers, and combinations thereof, and / or the at least one three-dimensional support element contains or consists of a material selected from the group consisting of ceramics, metals, alloys, metal oxides, plastics, glass, wood, and combinations thereof, and / or the polymer matrix is ​​arranged in the form of at least one layer on the at least one support element, which has a layer thickness in the range of 100 .m to 10 mm, preferably in the range of 150 µm to 1 mm, particularly preferably in the range of 200 .m to 500 µm.

8. A method for producing a composite material according to one of the preceding claims, wherein a) a liquid starting material for an at least partially gas-permeable and non-intrinsically electrically conductive polymer matrix is ​​applied layer by layer to at least one support element, and b) at least one curing process is carried out in which the polymer matrix is ​​formed from the applied starting material, wherein microparticles, each comprising a structure of nanoparticles, are introduced into the starting material before step a) or between step a) and step b), and wherein, when step b) begins, the microparticles are completely covered by the starting material.

9. The method according to claim 8, characterized in that the liquid starting material comprises at least one solvent and at least one polymer selected from the group consisting of polysiloxanes, polymethyl methacrylate, inorganic-organic hybrid polymers, polyvinylpyrrolidone, hydroxyethylcellulose, polylactides, and mixtures thereof, or at least one precursor, preferably in the form of monomers and / or oligomers, from which at least one polymer is formed during the at least one curing process, preferably by crosslinking, which is selected from the group consisting of polysiloxanes, polymethyl methacrylate, inorganic-organic hybrid polymers, polyvinylpyrrolidone, lidon, hydroxyethylcellulose, polylactides, and mixtures thereof.

10. Method according to claim 8 or 9, characterized in that the at least one curing process takes place at a temperature in the range of 5 °C to 40 °C, preferably in the range of 10 °C to 30 °C, particularly preferably at room temperature, and / or under exclusion of light.

11. Method according to one of claims 8 to 10, characterized in that the at least one carrier element is at least one carrier particle, wherein in step a) the liquid starting material is applied layer by layer to the at least one carrier particle by mixing the liquid starting material with the at least one carrier particle, and wherein the microparticles are introduced into the at least one applied starting material between step a) and step b) by mixing the microparticles with the at least one carrier particle onto which the starting material is applied.

12. Method according to claim 11, characterized in that the mixing of the liquid starting material with the at least one carrier element takes place for a duration of 0.1 to 15 minutes, preferably 1 to 2.5 minutes, and / or the mixing of the microparticles with the at least one carrier element onto which the starting material is applied takes place for a duration of 0.1 to 15 minutes, preferably 0.5 to 2.5 minutes.

13. Method according to one of claims 8 to 10, characterized in that the at least one support element is in the form of at least one planar support element, preferably in the form of a film, a plate or a disc, or in the form of at least one three-dimensional support element, which preferably has an extent of more than 2.5 cm in at least one spatial direction. is formed, wherein the microparticles are introduced into the at least one starting material prior to step a) by mixing the microparticles with the at least one starting material, and wherein in step a) the liquid starting material into which the microparticles have been introduced is applied to the at least one carrier element by means of at least one coating process.

14. Method according to claim 13, characterized in that the mixing of the microparticles with the at least one starting material takes place for a duration of 0.1 to 15 minutes, preferably 1 to 2.5 minutes, and / or the at least one coating process is selected from the group consisting of doctor blade coating, centrifugal coating, dip coating, spray coating, brushing, printing, and combinations thereof, and / or after step b) the polymer matrix is ​​separated from the at least one carrier element.

15. Use of a composite material according to any one of claims 1 to 7 for air and water purification, in agricultural systems for the targeted release (“delivery systems”) of fertilizers or pesticides, for energy storage and conversion, for catalysis, for the indication of environmental influences (as a sensor or recorder), for the indication of gases, e.g. hydrogen, for the marking of materials, as structural colors, as a recycling aid.

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