CN118786170A - Method for preparing porous material - Google Patents

Abstract

The present invention relates to a method for preparing a porous material, which comprises at least the following steps: providing a mixture (M1) comprising at least one compound (C1) selected from bio-based polymers and at least one polyionic biopolymer as component (C2) and water; contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A); exposing the obtained gel (A) to a water-miscible solvent (L) to obtain a gel (B); and drying the gel (B). The present invention also relates to a porous material that can be obtained in this way, and the use of the porous material as a thermal insulation material, as a carrier material for loading and releasing active substances, for electrode materials in batteries, fuel cells or electrolysis, for catalysis, for capacitors, for consumer electronics, for building and construction applications, for home and commercial appliance applications, for temperature-controlled logistics applications, for vacuum insulation applications, for battery applications, for clothing applications, for food applications, for cosmetic applications, for biomedical applications, for agricultural applications, for consumer applications, for packaging applications or for pharmaceutical applications, or as a carrier material or adsorbent.

Description

Method for preparing porous material

The present invention relates to a method for preparing a porous material, which comprises at least the following steps: providing a mixture (M1) comprising at least one compound (C1) selected from bio-based polymers and at least one polyionic biopolymer as component (C2) and water; contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A); exposing the obtained gel (A) to a water-miscible solvent (L) to obtain a gel (B); and drying the gel (B). The present invention also relates to a porous material that can be obtained in this way, and the use of the porous material as a thermal insulation material, as a carrier material for loading and releasing active substances, for electrode materials in batteries, fuel cells or electrolysis, for catalysis, for capacitors, for consumer electronics, for building and construction applications, for home and commercial appliance applications, for temperature-controlled logistics applications, for vacuum insulation applications, for battery applications, for clothing applications, for food applications, for cosmetic applications, for biomedical applications, for agricultural applications, for consumer applications, for packaging applications or pharmaceutical applications, or as a carrier material or adsorbent.

Porous materials based on organic polymers, such as polymer foams, having pores in the size range of a few micrometers or significantly smaller and a high porosity of at least 70%, are particularly suitable for a variety of applications.

Such porous materials with a small average pore size may be in the form of an organic aerogel or xerogel prepared, for example, by a sol-gel process and subsequently dried. In the sol-gel process, a sol based on an organogel precursor is first prepared, which is then gelled to form a gel by a crosslinking step. In order to obtain a porous material, such as an aerogel, from the gel, the liquid must be removed. For simplicity, this step is referred to hereinafter as drying.

The present invention relates to a method for producing a porous material containing a bio-based polymer and a polysaccharide having carboxylic acid groups, as well as the porous material and the use thereof.

In the context of the present invention, bio-based polymers are understood to be polymers obtained from renewable resources (algae, bacteria, microorganisms, plants, etc.). Bio-based polymers can be obtained mainly by two different methods: direct production of polymers or preparation of bio-based monomers and their further (bio)chemical polymerization. Direct production of biopolymers can be achieved by microorganisms (polyhydroxyalkanoates, PHA), algae (alginate, etc.), superior strains (pectin, etc.) or several types of producers, for example, cellulose can be produced by superior strains or by bacteria, and chitosan can be produced by crustaceans or by fungi.

In particular, the present invention relates to a method for producing a porous material containing protein, lignin, tannin, cellulose, silica and/or alginate. Lignin is a heterogeneous biopolymer. Depending on its source, such as wood or plant source and the extraction method, the properties, such as molar mass or degree of condensation, and the chemical composition may vary. Generally, lignin is a heterogeneous biopolymer with three main structural units, namely coumarin, coniferyl and sinapyl alcohol. Other suitable bio-based polymers are, for example, tannins. Tannins can be natural products found in bark and other biological sources. There are several types of tannins, which generally differ in their basic or monomeric units.

In principle, porous materials based on organic polymers, preferably bio-based polymers, such as polysaccharides, polypeptides, polyphenols such as cellulose, gelatin and lignin or mixtures of bio-based polymers are known from the prior art. Methods for preparing lignin-based aerogels are also known from the prior art.

In the scientific literature, several methods are disclosed. For example, an article in Journal of Supercritical Fluids 2015, 105, 1-8 discloses a method for preparing a mixed alginate-lignin aerogel by gelation using pressurized carbon dioxide. An alkaline aqueous solution of alginate and lignin containing calcium carbonate is exposed to CO ₂ to form a hydrogel.

US020190329208A1 discloses a method for preparing high-purity lignin-based carbon aerogel.

Highly porous organic aerogels based on tannin and lignin are disclosed in "New Tannin-Lignin Aerogels", Grishechko, L. et al. Industrial Crops and Products, 41 (2013) 347-355. Hydrogels are described, which are prepared at a constant solid weight fraction and a constant pH, but at different tannin/lignin and (tannin+lignin)/formaldehyde weight ratios.

Typically, organic molecules such as isocyanates or aldehydes are used as crosslinkers. For many applications, these compounds are disadvantageous because they are often harmful and traces may remain in the obtained material.

Likewise, porous materials based on alginate are known from the prior art. From WO 94/00512, a method for manufacturing polysaccharide foams (particularly based on alginate) is known. Also in the scientific literature, a gelation method induced by pressurized _CO2 is disclosed in alginate-based systems, for example in Partap et al. (2006, "Supercritical Carbon Dioxide in Water" Emulsion-Templated Synthesis of Porous Calcium Alginate Hydrogels. Advanced Materials 18, 501-504).

Aerogels or xerogels are also used as adsorbents or carrier materials due to their porosity and stability. For example, WO2016032733A2 describes non-dusty biopolymer aerogels for loading liquid active substances, but the loading is carried out using a supercritical medium at high pressure and high temperature. WO2019167013A1 describes superabsorbent polysaccharide biopolymer aerogels, but chemical crosslinking is required.

EP3741794A1 describes an aerogel/hydrogel composite material for loading and releasing oil or moisture, such as fragrance, but uses dusty silica aerogel, which needs to be hydrophobized. EP2663395B1 describes an aerogel/hydrogel composite material for loading and releasing drugs, but uses dusty silica aerogel, which needs to be hydrophobized.

CN114958480A records silica aerogel as a carrier for flavors, but the material is dusty and needs to be hydrophobized. WO2018056652A records silica aerogel as a carrier for UV blockers to prevent skin irritation, but the silica aerogel is dusty. WO2017023702A1 records silica aerogel/polymer resin as a flavor release material, but silica aerogel is known to be dusty and needs to be hydrophobized. Budtova et al. (Cellulose 2019, 26, 81-121 (10.1007/s10570-018-2189-1)) records cellulose aerogel for the absorption of oils or organic solvents, but requires chemical crosslinking and/or hydrophobization.

CN105601983B describes freeze-dried polysaccharide biopolymer materials as flavor carriers, but chemical cross-linking is required. WO2019190379A1 describes a mixed aerogel of cellulose and a loadable polysaccharide, but gelation requires energy due to heating.

The use of aerogels in pharmaceutical applications is disclosed, for example, in WO 96/25950 A1, WO 9501165 A1, WO 2009062975 A1 or WO 02051389 A2.

The materials disclosed in the prior art are either based on silica which is dusty and generally requires hydrophobization, or they are based on chemically crosslinked biopolymers, or they require energy input for loading and heating during the preparation process.

It is an object of the present invention to avoid the above-mentioned disadvantages. It is an object of the present invention to provide a method for preparing a porous material based on bio-based polymers, which avoids harmful materials. Another object of the present invention is to provide porous materials that are suitable as cores for thermal insulation or vacuum insulation, or for battery applications or for electrode materials in batteries, fuel cells or electrolysis, for catalysis, for capacitors, or for cosmetic, pharmaceutical or agricultural applications. Furthermore, it is an object of the present invention to provide a method for preparing a porous material from a bio-based polymer, which porous material can be used as an adsorbent or carrier material, which is stable and preferably also suitable for releasing liquids that have been adsorbed.

Another object of the present invention is to provide a porous material prepared from a harmless aqueous solution that can load a liquid or liquefied organic solvent or oil while showing less shrinkage when exposed to typical environmental conditions for storage stability.

According to the present invention, this object is achieved by a method for preparing a porous material, the method comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound selected from bio-based polymers (C1) and at least one polyionic biopolymer as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c).

According to another embodiment, the present invention also relates to a method for preparing a porous material, the method comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound (C1) selected from water-soluble bio-based polymers and inorganic precursors, and at least one water-soluble polysaccharide having carboxylic acid groups as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c).

According to the present invention, bio-based polymers and polyionic biopolymers are used to form gels. Suitable bio-based polymers and polyionic biopolymers are known in principle from the prior art. Preferably, polyanionic biopolymers are used as polyionic biopolymers. Suitable ionic biopolymers are, for example, polysaccharides, in particular polysaccharides with carboxylic acid groups.

According to the present invention, preferably use bio-based polymer, inorganic precursor and polysaccharide with carboxylic acid group to form gel.Suitable bio-based polymer, inorganic precursor and polysaccharide with carboxylic acid group are known in principle by prior art.Particularly suitable for water-soluble biopolymer or the biopolymer that forms swelling dispersion in water.Suitable polysaccharide with carboxylic acid group is for example alginate, pectin, modified cellulose, xanthan gum, hyaluronic acid or modified starch.These bio-based polymer and polyion biopolymer (for example polysaccharide and derivative thereof) are particularly attractive because of their stability, availability, reproducibility and low toxicity.In the context of the present invention, suitable inorganic precursor must be soluble or at least partially soluble in the mixture (M1), and must solidify in the gelling step.

For the purposes of the present invention, gels are crosslinked systems based on polymers that exist in contact with a liquid (called solvogel or lyogel) or as a liquid together with water (aquagel or hydrogel). In this context, the polymer phase forms a continuous three-dimensional network.

In the context of the present invention, water-soluble means sufficient solubility in water to form a solution which can be used to prepare a gel. In the context of the present invention, it is also possible to use aqueous swelling dispersions to prepare gels.

According to the invention, the gel is formed from the components of the mixture (M1) and at least one polyvalent metal ion. The components (C1) and (C2) used in the process of the invention must be suitable for forming a gel with the polyvalent metal ions and must in particular have suitable functional groups.

It was unexpectedly found that the claimed method makes it possible to produce aerogels prepared from harmless aqueous solutions, which can be loaded with liquid or liquefied organic solvents or oils, and which show less shrinkage when exposed to typical storage stability environmental conditions, and which also show less shrinkage when loaded to maximize liquid capacity, which is dust-free and does not require chemical treatments such as hydrophobization or covalent crosslinking. The porous material obtained shows less shrinkage in dry aerogel form, so the available volume remains large until the loading of the aerogel occurs. Unexpectedly, the method according to the invention makes it possible to form round hydrogels, alcohol gels and aerogel beads. The aerogel beads preferably show a shrinkage of less than 50% when exposed to typical environmental conditions, and preferably show a shrinkage of less than 20% when the aerogel beads are loaded with active ingredients or liquids. Preferably, according to the invention, the biopolymer is 100% bio-based and the aerogel does not require chemical crosslinking or hydrophobization.

Preferably, the porous material obtained according to the method of the present invention is suitable for loading liquid or liquefied organic solvents or oils, and generally shows a shrinkage of less than 60% when exposed to humidity (60% rH, 48h, 30°C) as a dry aerogel, and generally shows a shrinkage of less than 50% when loaded in the shape of spherical beads with an average diameter of about 3 mm.

Surprisingly it has been found that the claimed process allows the production of aerogels, for example based on bio-based polymers and inorganic precursors, and at least one polysaccharide having carboxylic acid groups, having a low solids content and a high surface area, preferably also a high pore volume and a small pore size.

The properties of the aerogel can be tailored by adjusting the composition of the mixture (M1), the reaction conditions during the hydrogel (gel (A)) formation phase or the solvent exchange process and the drying step. According to the present invention, the properties of the hydrogel and/or aerogel can be influenced by varying the ratio of the components and by controlling the parameters of step b) and by introducing a wide range of organic and inorganic materials into the gel matrix.

According to the present invention, at least one compound (C1) is used. Suitable bio-based polymers include, for example, bio-based phenolic polymers, such as lignin and tannin. Suitable, for example, proteins, in particular plant-based proteins, animal-based proteins, bacterial-based proteins and fungal-based proteins, including, for example, yeast-based proteins from the food industry (e.g., beer brewing). According to the present invention, for example, cellulose, bacterial cellulose, modified cellulose, starch, sugar, chitosan, polyhydroxyalkanoates, whey protein isolate, potato protein isolate, starch protein isolate, gelatin, collagen, casein or derivatives thereof, such as salts thereof, can be used. Whey protein, pea protein, yeast protein and potato glycoprotein are particularly suitable for preparing porous materials suitable as carrier materials.

According to another embodiment, the present invention also relates to a method as described above, wherein compound (C1) is a protein, preferably a protein selected from the group consisting of whey protein, pea protein, yeast protein and potato protein, in particular a protein selected from the group consisting of whey protein.

Likewise, according to the invention, inorganic precursors such as silicates, titanates, vanadates, zirconates, aluminates, borates, ferrates, chromates, molybdates, tungstates, manganates, cobaltates and metal sulfides, metal oxides or metal carbides can also be used as compound (C1).

According to another embodiment, the present invention also relates to a method as described above, wherein compound (C1) is selected from the group consisting of water-soluble bio-based polyphenol polymers and silicon dioxide.

According to the present invention, the water-soluble bio-based polyphenol polymers may also be selected from lignin biopolymers and tannin biopolymers, in particular from alkali lignin, kraft lignin, hydrolyzed lignin, soda lignin, aquasolv solid lignin, enzymatic lignin, lignin sulfonate, lignin carboxylate, lignin derivatives, biorefining lignin, tannic acid or tannin and tannin derivatives.

According to another embodiment, the present invention also relates to a method as described above, wherein the water-soluble bio-based polyphenol polymer is selected from lignin biopolymers and tannin biopolymers, in particular selected from alkali lignin, kraft lignin, hydrolyzed lignin, soda lignin, water-soluble solid lignin, enzymatic lignin, lignin sulfonate, lignin carboxylate, lignin derivatives, biorefining lignin, tannic acid or tannin and tannin derivatives.

According to the present invention, a mixture of two or more bio-based polymers or a mixture of one or more bio-based polymers and a metal oxide may also be used as compound (C1). For example, a mixture comprising one or more polymers selected from bio-based polymers such as lignin and tannin, cellulose, bacterial cellulose, modified cellulose, starch, sugar, chitosan, polyhydroxyalkanoate, whey protein isolate, potato protein isolate, starch protein isolate, yeast protein, gelatin, collagen, casein or derivatives thereof, or a mixture comprising an inorganic precursor and one or more polymers selected from bio-based phenolic polymers such as lignin and tannin, cellulose, bacterial cellulose, modified cellulose, starch, sugar, chitosan, polyhydroxyalkanoate, whey protein isolate, potato protein isolate, starch protein isolate, gelatin, collagen, casein or derivatives thereof or pea protein or yeast protein may be used as component (C1).

According to the present invention, compound (C2) is preferably a polyanionic biopolymer, such as a polysaccharide. Compound (C2) can be selected from alginate, pectin, modified cellulose, xanthan gum, hyaluronic acid or modified starch. Therefore, according to another embodiment, the invention further relates to method as described above, wherein compound (C2) can be selected from alginate, pectin, modified cellulose, xanthan gum, hyaluronic acid or modified starch, preferably selected from alginate, pectin and modified cellulose, particularly selected from modified cellulose or selected from alginate.

According to another embodiment, the present invention also relates to a method as described above, wherein compound (C2) is a polyanionic biopolymer, preferably a polyionic biopolymer selected from the group consisting of alginates, pectins and modified celluloses.

According to the invention, compound (C1) may, for example, be selected from lignin and tannin, and cellulose, bacterial cellulose, modified cellulose, starch, sugars, chitosan, polyhydroxyalkanoates, whey protein isolate, potato protein isolate, starch protein isolate, gelatin, collagen, casein or derivatives thereof, and silicates, titanates, vanadates, zirconates, aluminates, borates, ferrates, chromates, molybdates, tungstates, manganates, cobaltates and metal sulfides, metal oxides and metal carbides, and compound (C2) may be an alginate. According to another embodiment, compound (C1) may, for example, be a mixture comprising compounds selected from the group consisting of lignin and tannin, cellulose, bacterial cellulose, modified cellulose, starch, sugars, chitosan, polyhydroxyalkanoates, whey protein isolate, potato protein isolate, starch protein isolate, yeast protein, gelatin, collagen, casein or derivatives thereof, as well as silicates, titanates, vanadates, zirconates, aluminates, borates, ferrates, chromates, molybdates, tungstates, manganates, cobaltates and metal sulfides, metal oxides or metal carbides, and compound (C2) may be an alginate.

According to another embodiment, compound (C1) is a protein, preferably a protein selected from the group consisting of whey protein, pea protein, yeast protein and potato protein, and compound (C2) is selected from the group consisting of alginates, pectins and modified celluloses.

According to the invention, the amount of compounds (C1) and (C2) used in the process can vary, for example depending on the properties of the material to be obtained. Suitable amounts of compound (C1) are, for example, 0.1% to 50% by weight, based on the weight of the mixture (M1), preferably 1.0 to 35% by weight, based on the weight of the mixture (M1), in particular 2.0 to 20% by weight, based on the weight of the mixture (M1).

Therefore, according to another embodiment, the present invention also relates to a process as described above, wherein the mixture (M1) comprises the compound (C1) in an amount of 0.1% to 50% by weight, based on the weight of the mixture (M1).

The ratio of compound (C1) to compound (C2) may also vary, depending on the compounds used. Typically, mixture (M1) comprises compound (C1) and compound (C2) in a ratio of 55:45 to 98:2, preferably 60:40 to 95:5.

Therefore, according to another embodiment, the present invention also relates to a process as described above, wherein the mixture (M1) comprises compound (C1) and compound (C2) in a ratio ranging from 55:45 to 98:2.

In the context of the present invention, the pH of the mixture (M1) may also vary depending on the compounds used. It has been found that advantageous results are obtained when the pH of the mixture (M1) is from 7 to 14, in particular from 8 to 14 or from 10 to 14, more preferably from 11 to 14. The pH of the mixture (M1) may be adjusted to increase the solubility of the polymer used.

According to another embodiment, the present invention also relates to a process as described above, wherein the pH value of the mixture (M1) is between 7 and 14.

In the method according to the invention, a mixture (M1) is provided according to step a). The mixture can be prepared by dissolving the required amounts of compounds (C1) and (C2) in, for example, distilled water. In the context of the present invention, the pH value of the mixture can also be adjusted to increase solubility.

According to step b), the mixture (M1) is contacted with an aqueous solution of polyvalent metal ions to prepare a gel (A).

For example, an aqueous solution of polyvalent metal ions can be prepared using a salt of the polyvalent metal ions.

According to the present invention, such a polyvalent metal ion is suitable: it forms a poorly soluble compound with a polysaccharide compound (C2) with a carboxylic acid group, and can form a poorly soluble compound with the compound (C1) used, that is, it acts as a cross-linking metal ion. This polyvalent metal ion includes, for example, alkaline earth metal ions and transition metal ions, which form poorly soluble compounds with polysaccharides with carboxylic acid groups. Alkaline earth metal ions, such as magnesium or calcium are preferred. Calcium is particularly preferred. Similarly, trivalent metal ions such as aluminum or iron are also particularly suitable. According to the present invention, calcium salts are particularly preferred because they are physiologically, particularly cosmetically acceptable compared to alginate, and have strong crosslinking and/or gelation. In addition, for example beryllium, barium, strontium, zinc, cobalt, nickel, copper, manganese, iron, chromium, vanadium, titanium, zirconium, cadmium, molybdenum, tungsten, ruthenium, rhodium, iridium, palladium, platinum, aluminum can also be used. According to the present invention, a mixture of two or more polyvalent ions can also be used, for example, a mixture comprising divalent and trivalent ions, for example, a mixture comprising calcium and aluminum or a mixture comprising calcium and ions.

The polyvalent metal ions are preferably added in the form of their salts. In principle, the corresponding anions can be selected arbitrarily. Preferably, chlorides, acetates, nitrates, preferably calcium chloride or trivalent metal salts, such as iron (III) chloride, aluminum chloride or iron (III) nitrate or mixtures thereof, can be used.

The amount of the polyvalent metal ion salt is selected so that the concentration of the salt in the resulting solution is preferably about 1 to 20% by weight, preferably 1 to 10% by weight, in particular 1 to 5% by weight, more preferably 1 to 3% by weight.

According to another embodiment, the present invention also relates to a method as described above, wherein the polyvalent metal ion is a divalent metal ion, in particular a divalent metal ion selected from alkaline earth metal ions.

According to another embodiment, the present invention also relates to a method as described above, wherein the polyvalent metal ions are trivalent metal ions selected from aluminum ions and iron (III) ions.

According to the invention, it is also possible to use mixtures of polyvalent metal ions.

The mixture (M1) provided in step (a) may also comprise further salts, in particular such salts which do not form a gel, and also customary auxiliaries known to the person skilled in the art as further ingredients.

Furthermore, the mixture (M1) may comprise cosmetic or medical active substances or medicaments or agricultural agents or food active substances.

Typically, under the conditions of the process according to the invention, the cosmetic or medical active substance or the pharmaceutical agent or the agricultural agent or the food active substance is at least partially retained in the gel or porous material.

Suitable are, for example, substances which are water-soluble or dispersible in water.

Suitable substances can be selected, for example, from hyaluronic acid, collagen, keratin, fibroin, tannin, lignin (both as antioxidants or sunscreen factors), enzymes, polyvinylpyrrolidone (PVP) and povidone. In addition, suitable additives can be whitening actives; free radical scavengers, UV absorbers, barrier lipids, desquamation actives, retinoids, tanning actives, skin lighteners, skin activators, chelating agents, flavonoids, moisturizing actives, exfoliants, anti-acne actives, anti-caking agents, anti-fat agents, defoamers, antifungal actives, anti-inflammatory actives, antibacterial actives, antioxidants, antiperspirant/deodorant actives, anti-skin atrophy actives, antiviral agents, anti-wrinkle actives, artificial colorants (artificial tanning actives). agents) and enhancers, astringents, barrier repair agents, adhesives, buffers, bulking agents, chelating agents, colorants, dyes, enzymes, essential oils, film formers, fragrances, humectants, hydrocolloids, light diffusers, nail polish, sunscreens, optical brighteners, optical modifiers, particulates, perfumes, pH adjusters, preservatives, masking agents, skin conditioners/moisturizers, skin feel modifiers, skin protectants, skin sensates, skin therapeutics, skin exfoliants, skin lightening agents, skin soothing and/or healing agents, skin thickening agents, sunscreen actives, local anesthetics, vitamin compounds, and combinations thereof.

Suitable materials may be triglycerides, vegetable oils, vegetable oil derivatives, acetylglycerides, allcyl esters, allcenyl esters, lanolin and its derivatives, wax esters, beeswax derivatives, sterols and phospholipids, and combinations thereof; hydrocarbon oils and waxes or silicone oils, and combinations thereof.

Suitable substances may also be pharmaceutical compositions comprising one or more agents, preferably for oral administration. The one or more agents are selected from therapeutic agents and diagnostic agents. Examples of suitable therapeutic agents include, but are not limited to, drugs acting at synaptic sites and neuroeffector binding sites; general and local analgesics; hypnotics and sedatives; drugs for treating psychiatric disorders such as depression and schizophrenia; anti-epileptics and anticonvulsants; drugs for treating Parkinson's and Huntington's diseases, aging and Alzheimer's disease; excitatory amino acid antagonists, neurotrophic factors and neuroregenerative agents; trophic factors; drugs for treating CNS trauma or stroke; drugs for treating addiction and drug abuse; anti-obesity drugs; autoactive substances and anti-inflammatory drugs The invention relates to drugs for treating diseases caused by parasites and microorganisms; chemotherapeutics for parasitic infections and diseases caused by microorganisms; immunosuppressants and anticancer drugs; hormones and hormone antagonists; heavy metals and heavy metal antagonists; non-metallic toxicant antagonists; cytostatics for treating cancer; diagnostic substances for nuclear medicine; immunoactive and immunoreactive agents; transmitters and their respective receptor agonists and receptor antagonists, their respective precursors and metabolites; transporter inhibitors; antibiotics; antispasmodics; antihistamines; antinauseants; relaxants; stimulants; sense and antisense oligonucleotides; cerebral dilators; psychotropic drugs; antimanics; vasodilators and constrictors; antihypertensive drugs; drugs for treating migraines; hypnotics, hyperglycemic drugs and hypoglycemic drugs; antiasthmatic drugs; antivirals, preferably anti-HIV drugs; genetic materials suitable for DNA, si-RNA or antisense treatment of diseases; and mixtures thereof. Examples of suitable diagnostic agents include, but are not limited to, diagnostic agents suitable for use in the diagnosis of nuclear medicine and radiotherapy.

Suitable substances can also be flavors or flavor compositions, which are usually at least partially retained in gels or porous materials under the conditions of the inventive method. Flavors can be any aromatic substance or mixture of substances, including natural and synthetic substances that provide good aroma. In addition, flavors can include auxiliary materials, such as fixatives, fillers, stabilizers and solvents. Examples of suitable flavors include, but are not limited to, silicone oils, essential oils, absolute oils, resinous substances, resins and synthetic perfume components, such as hydrocarbons, alcohols, aldehydes, ketones, ethers, acids, esters, acetals, ketals, nitrites, including saturated and unsaturated compounds, aliphatic compounds, carbocyclic compounds and heterocyclic compounds. It should be recognized that specific flavors may include additional components, which play the role of, for example, carriers, diluents, stabilizers, etc. Exemplary additional components include ethylene glycol and vegetable oils. Mention that the flavor components include flavors and any additional components combined with flavors to provide beneficial properties such as stability, viscosity, etc. For example, examples of suitable flavors or perfumes are provided in U.S. Patent No. 5,234,610.

According to another embodiment, the present invention also relates to a method as described above, wherein compound (C) is added to the mixture (M1) suitable for forming a gel in step a). Compound (C) may be soluble or partially soluble in mixture (M1). In the context of the present invention, compound (C) may also be insoluble in mixture (M1).

According to another embodiment, the present invention also relates to a process as described above, wherein a water-insoluble solid (S) is contacted with the mixture (M1).

For example, the solid (S) may be a porous material or a foam, a carrier or a fibrous material. According to the invention, the mixture (M1) may also be present in the pores of the solid (S).

According to another embodiment, the present invention also relates to a process as described above, wherein a compound (C) is added to the mixture (M1) and is selected from the group consisting of pigments, sunscreens, flame retardants, metals, metal particles, metal nanoparticles, metal fibers, metal meshes, metal oxides, metal oxide particles, metal oxide nanoparticles, metal oxide fibers, metal salts, metals for catalysis, catalytic materials, metal carbide or metal sulfide particles or nanoparticles, silicon-based materials, silicon particles, silicon nanoparticles, semiconductor-based materials, semiconductor particles, semiconductor nanoparticles, semiconductor fibers, semiconductor meshes, carbon materials, carbon black, graphite nanoparticles, graphite fibers, graphite flakes, graphite meshes, graphene nanoparticles, graphene fibers, graphene flakes, graphene meshes, metal organic frameworks, sulfur, inorganic and/or organic fillers, nucleating agents, stabilizers, thermal control elements, surfactants, fibers and foam reinforcements.

According to step b) of the present invention, the mixture (M1) is contacted with an aqueous solution of polyvalent metal ions to prepare the gel (A). Suitable mixing steps are known in principle to those skilled in the art. For example, the mixture (M1) can be added dropwise to an aqueous solution of polyvalent metal ions. It is also possible to provide the mixture (M1) in the pores of a carrier material or to mix it with fibers before contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare the gel (A). In addition, the mixture (M1) can be contacted with the polyvalent metal ions during emulsification or spraying.

Gelation itself is known to the person skilled in the art and is described, for example, on page 21, line 19 to page 23, line 13 of WO 2009/027310.

Preferably, the conditions are adjusted and the hydrogel, alcohol gel and/or aerogel exhibits a round shape. Preferably, according to step b), round beads with an average diameter of 0.5 to 3 mm are obtained. Preferably, no crosslinking or hydrophobization via covalent chemical reactions occurs.

Preferably, the temperature and pressure in step b) are adjusted to gel-forming conditions. Suitable temperatures may be 5 to 40°C, preferably 15 to 35°C. According to another embodiment, the present invention also relates to a method as described above, wherein step b) is carried out at a temperature of 5 to 40°C.

By choosing suitable conditions for step b), the rate of formation of the insoluble gel can be controlled very accurately and easily.

The gel (A) obtained in step b) is a gel comprising water, ie a hydrogel. According to the invention, the gel (A) obtained in step b) is exposed to a water-miscible solvent (L) to obtain the gel (B) in step c) of the process of the invention.

However, it is also possible to use the hydrogel (A) obtained itself as an intermediate in the process as disclosed above. Many applications of hydrogels are known. The hydrogel (A) is particularly homogeneous and particles can be prepared according to the invention which can be subjected to further process steps.

According to the invention, a water-miscible solvent (L) is used in step c). In the context of the present invention, water-miscible means that the solvent is at least partially miscible with water, so that an exchange of the solvent in the gel is possible.

The solvent exchange is carried out by immersing the gel directly in the new solvent (one step) or by subsequent immersion in different water-to-new solvent mixtures (multiple steps), wherein the content of the new solvent is increased after a certain time (exchange frequency) of the previous immersion step (Robitzer et al., 2008, Langmuir, 24 (21), 12547-12552). The solvent selected to replace water must meet the requirements of not dissolving the gel structure, being completely soluble in the previous solvent (water), and preferably also being considered to be usable for the manufacture of drugs. In addition, if the method comprises a supercritical drying step, the solvent (L) is preferably at least partially miscible with the supercritical medium.

The solvent (L) can in principle be any suitable compound or mixture of compounds which meets the above requirements, wherein the solvent (L) is liquid under the temperature and pressure conditions of step c).

For example, possible solvents (L) are alcohols, ketones, aldehydes, alkyl alkanoates, organic carbonates, amides such as formamide and N-methylpyrrolidone, sulfoxides such as dimethyl sulfoxide, aliphatic and alicyclic halogenated or non-halogenated hydrocarbons, halogenated or non-halogenated aromatic compounds and fluorinated ethers. Mixtures of two or more of the above compounds are also possible.

In many cases, particularly suitable solvents (L) are obtained by using two or more completely miscible compounds selected from the abovementioned solvents.

Suitable solvents are, in particular, alcohols and ketones, for example C1 to C6 alcohols and C1 to C6 ketones and mixtures thereof.

According to another embodiment, the present invention also relates to a process as described above, wherein the solvent (L) used in step c) is selected from C1 to C6 alcohols and C1 to C6 ketones and mixtures thereof.

Particularly suitable are alcohols, such as methanol, ethanol and isopropanol, and ketones, such as acetone and methyl ethyl ketone.

The solvent exchange according to step b) can be carried out in one, two, three or more steps using solvents of different concentrations. According to a preferred embodiment, the gel (A) is sequentially immersed in ethanol/water mixtures of, for example, 30, 60, 90 and 100 wt %, each time for 5 min to 12 h depending on the particle size and porosity.

In step c), a gel (B) is obtained. According to step d) of the process of the invention, the gel (B) obtained in step c) is dried.

The drying in step d) is carried out in a known manner. Preferably, the drying is carried out under supercritical conditions, preferably after replacing the solvent with CO ₂ or another solvent suitable for the purpose of supercritical drying. Such drying per se is known to the person skilled in the art. Supercritical conditions characterize the temperature and pressure at which CO ₂ or any solvent used to remove the gelling solvent is present in a supercritical state. In this way, the shrinkage of the gel during the solvent removal can be reduced.

In the context of the present invention, it is also possible to dry the obtained gel by converting the liquid contained in the gel into a gaseous state at a temperature and a pressure below the critical temperature and the critical pressure of the liquid contained in the gel.

According to one embodiment, the drying of the obtained gel is preferably carried out by converting the solvent (L) into a gaseous state at a temperature and pressure lower than the critical temperature and critical pressure of the solvent (L). Therefore, preferably, the drying is carried out by removing the solvent (L) present in the reaction without previously replacing it with another solvent.

Such a method is likewise known to the person skilled in the art and is described on page 26, line 22 to page 28, line 36 of WO 2009/027310.

According to another embodiment, the invention also relates to a process as described above, wherein the drying according to step d) is carried out by converting the liquid contained in the gel into the gaseous state at a temperature and a pressure below the critical temperature and the critical pressure of the liquid contained in the gel.

According to another embodiment, the present invention also relates to a process as described above, wherein the drying according to step d) is carried out under supercritical conditions.

The method may also include one or more further modification steps, such as a molding step, a compression step, a lamination step, a hydrophobization step or a carbonization step that may include fibers and/or binders and/or thermoplastic materials. For example, one or more of these steps may be combined, such as post-drying and a hydrophobization step.

According to another embodiment, the present invention also relates to a method as described above, wherein said method comprises one or more further modification steps of said dried gel.

According to another embodiment, the present invention also relates to a method as described above, wherein the modification step is selected from a shaping step, a compression step, a lamination step, a post-drying step, a hydrophobization step and a carbonization step.

The invention also relates to a porous material obtained or obtainable by a method as described above. The porous material of the invention is preferably an aerogel or a xerogel or a cryogel.

For the purposes of the present invention, a xerogel is a porous material prepared by a sol-gel process, wherein the liquid phase is removed from the gel by drying below the critical temperature and below the critical pressure of the liquid phase ("subcritical conditions"). An aerogel is a porous material prepared by a sol-gel process, wherein the liquid phase is removed from the gel under supercritical conditions. A cryogel is a porous material prepared by freezing the solvent in the gel and removing the solid solvent by a sublimation process under ambient conditions.

The method described above produces porous materials with improved properties. Aerogels prepared according to the method of the invention preferably have a low density and preferably a high specific surface area, for example 200 to 800 ^m2 /g. In addition, for pore diameters <100 nm, preferably pore volumes of 2.1 to 9.5 ^cm3 /g are obtainable.

Preferably, the porous material obtained shrinks less than 60% when exposed to humidity (60% rH, 48 h, 30° C.) as a dry aerogel and less than 50% when loaded in the shape of beads with an average diameter of 3 mm.

Furthermore, the present invention therefore relates to a porous material obtained or obtainable by the method for preparing a porous material as disclosed above. In particular, the present invention relates to a porous material obtained or obtainable by the method for preparing a porous material as disclosed above, wherein the drying according to step d) is carried out under supercritical conditions.

The density of the porous material according to the invention is preferably from 0.005 to 1 g/cm ³ , preferably from 0.01 to 0.5 g/cm ³ (determined in accordance with DIN 53420).

The average pore size was determined by scanning electron microscopy and subsequent image analysis using a statistically significant number of pores. Corresponding methods are known to those skilled in the art. In order to characterize the porous structure of the aerogel, a Nova 3000 surface area analyzer from Quantachrome Instruments was used. It uses adsorption and desorption of nitrogen at a constant temperature of 77K.

The volume average pore size of the porous material is preferably not greater than 1 micrometer. The volume average pore size of the porous material is particularly preferably not greater than 750 nm, very particularly preferably not greater than 500 nm, in particular not greater than 250 nm. The volume average pore size of the porous material can, for example, be 1 to 1000 nm, preferably 2 to 500 nm, in particular 3 to 250 nm, more preferably 5 to 100 nm, or particularly preferably 10 to 50 nm.

The porosity of the porous material obtainable according to the invention is preferably at least 70% by volume, in particular 70 to 99% by volume, particularly preferably at least 80% by volume, very particularly preferably at least 85% by volume, in particular 85 to 95% by volume. The porosity in % by volume indicates that a specified proportion of the total volume of the porous material comprises pores. Although very high porosities are generally required from the perspective of minimum thermal conductivity, the upper limit of the porosity is determined by the mechanical properties and processability of the porous material.

According to another embodiment, the present invention also relates to the porous material as disclosed above, wherein the specific surface area of the porous material is from 200 to 800 m ² /g, determined using the BET theory according to DIN 66134:1998-0.

Surprisingly, it has been found that according to the invention, it is possible to obtain materials with very low contents of volatile organic compounds even though the raw materials used may contain relatively high amounts of volatile organic compounds. For example, due to the preparation process of lignin, it usually contains volatile organic compounds, such as guaiacol.

Therefore, according to another embodiment, the present invention also relates to a porous material as disclosed above, wherein the content of volatile organic compounds (VOC) in the porous material is less than 50% of the content of volatile organic compounds (VOC) in the feedstock used in the method.

According to another embodiment, the present invention also relates to the porous material as disclosed above, wherein the porous material is in the form of beads, preferably with an average diameter of 0.5 mm to 3 mm.

The porous material according to the present invention can be loaded with liquid or liquefied organic solvents or oils, and when exposed to typical storage stability environmental conditions, it shows less shrinkage, and when loaded to maximize liquid capacity, it also shows less shrinkage. The porous material according to the present invention shows less shrinkage in the form of dry aerogel, so until the loading of the aerogel occurs, its available volume is still large. The porous material according to the present invention has excellent adsorption properties and excellent mechanical stability, so that it can carry adsorbed substances under ambient conditions and allow stable release.

According to the invention, in the preparation method described above, for example cosmetic or medical active substances or pharmaceutical agents or agricultural agents or food active substances or fragrances or fragrance compositions can be introduced, which substances are then at least partially present in the porous material and can also be released under appropriate conditions.

According to the present invention, the porous material can also be contacted with a suitable liquid composition comprising a cosmetic or medical active substance or a medicament or an agricultural agent or a food active substance or a flavor or a flavor composition, which is then at least partially adsorbed. Preferably, the method comprises mixing the porous material with the liquid composition and keeping enough time to adsorb the composition of an effective amount onto the porous material and/or be absorbed by the porous material. The liquid composition can be a solution, preferably a high concentration solution. Suitable liquid compositions are solutions or dispersions such as comprising cosmetic or medical active substances or medicaments or agricultural agents or food active substances or a flavor or a flavor composition and a suitable solvent. In the context of the present invention, liquid active substances can also be used without adding solvents. Then, the porous material containing the adsorbed substance can be separated from any remaining solution or dispersion. According to the present invention, under appropriate conditions, the adsorbed substance can also be released.

The loading amount of the liquid composition depends on the density of the liquid, the density of the dry porous material and the shrinkage of the dry porous material after loading the liquid composition. The loading amount of the liquid composition can be as high as 60 g/g, preferably as high as 50 g/g, more preferably as high as 45 g/g and as low as 5 g/g, preferably as low as 7 g/g.

According to another aspect, the present invention relates to the use of a porous material as disclosed above or a porous material obtained or obtainable by a method as disclosed above as a support material or adsorbent.

The porous material obtainable according to the invention preferably has a high porosity and a low density. In addition, the porous material preferably has a small average pore size. The combination of the above properties makes it possible to use the material as a thermal insulation material in the field of thermal insulation, in particular as a building material in a ventilated state or in refrigerators, temperature-controlled logistics, clothing or batteries.

The invention also relates to the use of a porous material as disclosed above or a porous material obtained or obtainable according to a method as disclosed above as a thermal insulation material or for a vacuum insulation panel. The thermal insulation material is, for example, a thermal insulation material for the interior or exterior of a building. The porous material according to the invention can be advantageously used in thermal insulation systems, for example in composite materials.

Furthermore, the present invention also relates to the use of the porous material according to the invention for battery applications, for electrode materials in batteries, fuel cells or electrolysis, for catalysis, for capacitors, for cosmetic applications, for biomedical applications, for pharmaceutical applications, for agricultural applications and for the manufacture of medical products. Such cosmetic applications include, for example, products for facial care, or products as skin scrubs or cleansing or protection products, for example products for UV protection or products containing antioxidants.

According to another aspect, the present invention relates to the use of a porous material as disclosed above or a porous material obtained or obtainable by a method as disclosed above as a thermal insulation material, for cosmetic applications, for biomedical applications or for pharmaceutical applications. According to another preferred aspect, the present invention relates to the use of a porous material as disclosed above or a porous material obtained or obtainable by a method as disclosed above as a thermal insulation material, as a carrier material for loading and releasing active substances, for electrode materials for batteries, fuel cells or electrolysis, for catalysis, for capacitors, for consumer electronics, for building and construction applications, for household appliance applications, for temperature-controlled logistics applications, for vacuum insulation applications, for battery applications, for clothing applications, for food applications, for cosmetic applications, for biomedical applications, for agricultural applications, for consumer applications, for packaging applications or for pharmaceutical applications.

Preferred embodiments can be found in the claims and the description. Combinations of preferred embodiments do not go beyond the scope of the invention. Preferred embodiments of the components used are described below.

The present invention includes the following embodiments including specific combinations of embodiments as indicated by the respective inter-reference relationships defined therein.

1. A method for preparing a porous material, comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound (C1) selected from water-soluble bio-based polymers and inorganic precursors, and at least one water-soluble polysaccharide having carboxylic acid groups as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c).

2. The method according to embodiment 1, wherein compound (C1) is selected from water-soluble bio-based polyphenol polymers and silicon dioxide.

3. The process according to any one of embodiments 1 or 2, wherein the mixture (M1) comprises the compound (C1) in an amount of 0.1% to 50% by weight, based on the weight of the mixture (M1).

4. The method according to any one of embodiments 1 to 3, wherein the mixture (M1) comprises compound (C1) and compound (C2) in a ratio of 55:45 to 98:2.

5. The method according to any one of embodiments 1 to 4, wherein the pH value of the mixture (M1) is 7 to 14, in particular 8 to 14.

6. The method according to any one of embodiments 1 to 5, wherein the polyvalent metal ion is a divalent metal ion, in particular a divalent metal ion selected from alkaline earth metal ions, or wherein the polyvalent metal ion is a trivalent metal ion selected from aluminum ions and iron (III) ions.

7. The method according to any one of embodiments 1 to 6, wherein the method comprises one or more further modification steps of the dried gel, in particular wherein the modification step is selected from a forming step, a compression step, a lamination step, a post-drying step, a hydrophobization step and a carbonization step.

8. The process according to any one of embodiments 1 to 7, wherein the solvent (L) used in step c) is selected from C1 to C6 alcohols and C1 to C6 ketones, and mixtures thereof.

9. The process according to any one of embodiments 1 to 8, wherein a water-insoluble solid (S) is contacted with the mixture (M1).

10. A method according to any one of embodiments 1 to 9, wherein a compound (C) is added to the mixture (M1), wherein the compound (C) is selected from pigments, sunscreens, flame retardants, catalytic materials, metals, metal oxides, metal sulfides, metal carbides, metal salts, silicon-based materials, carbon-based materials, metal organic frameworks, semiconductors, sulfur, fillers, surfactants, thermal control elements, fibers and foam reinforcements.

11. The method according to any one of embodiments 1 to 10, wherein the drying according to step d) is carried out by converting the liquid contained in the gel into the gaseous state at a temperature and a pressure below the critical temperature and the critical pressure of the liquid contained in the gel.

12. The method according to any one of embodiments 1 to 10, wherein the drying according to step d) is carried out under supercritical conditions.

13. A porous material obtained or obtainable by the method according to any one of embodiments 1 to 12.

14. The porous material according to embodiment 13, wherein the specific surface area of the porous material is 200 to 800 m ² /g, determined using the BET theory according to DIN 66134:1998-0, and the pore volume is 2.1 to 9.5 cm ³ /g for pore diameters <150 nm.

15. The porous material according to embodiment 13 or 14, wherein the content of volatile organic compounds (VOC) in the porous material is less than 50% of the content of volatile organic compounds (VOC) in the raw material used in the method.

16. Use of the porous material according to any one of embodiments 13 to 15 or the porous material obtained or obtainable by the method according to any one of embodiments 1 to 12 as a thermal insulation material, as a carrier material for loading and releasing active substances, for battery applications, for electrode materials in batteries, fuel cells or electrolysis, for catalysis, for capacitors, for consumer electronics, for building and construction applications, for home appliance applications, for temperature-controlled logistics applications, for vacuum insulation applications, for clothing applications, for food applications, for cosmetic applications, for biomedical applications, for agricultural applications, for consumer applications, for packaging applications or for pharmaceutical applications.

17. A method for preparing a porous material, comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound (C1) selected from water-soluble bio-based polyphenol polymers and silicon dioxide, and at least one water-soluble polysaccharide having carboxylic acid groups as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c).

18. The method according to embodiment 17, wherein compound (C1) is selected from lignin biopolymers and silica.

19. The process according to any one of embodiments 17 or 18, wherein the mixture (M1) comprises the compound (C1) in an amount of 0.1% to 50% by weight, based on the weight of the mixture (M1).

20. The method according to any one of embodiments 17 to 19, wherein the mixture (M1) comprises compound (C1) and compound (C2) in a ratio of 55:45 to 98:2.

21. The method according to any one of embodiments 17 to 20, wherein the pH value of the mixture (M1) is from 7 to 14, in particular from 8 to 14.

22. The method according to any one of embodiments 17 to 21, wherein the polyvalent metal ion is a divalent metal ion, in particular a divalent metal ion selected from alkaline earth metal ions, or wherein the polyvalent metal ion is a trivalent metal ion selected from aluminum ions and iron (III) ions.

23. The method according to any one of embodiments 17 to 22, wherein the method comprises one or more further modification steps of the dried gel, in particular wherein the modification step is selected from a forming step, a compression step, a lamination step, a post-drying step, a hydrophobization step and a carbonization step.

24. The process according to any one of embodiments 17 to 23, wherein the solvent (L) used in step c) is selected from C1 to C6 alcohols and C1 to C6 ketones, and mixtures thereof.

25. The process according to any one of embodiments 17 to 24, wherein a water-insoluble solid (S) is contacted with the mixture (M1).

26. A method according to any one of embodiments 17 to 25, wherein a compound (C) is added to the mixture (M1), wherein the compound (C) is selected from pigments, sunscreens, flame retardants, catalytic materials, metals, metal oxides, metal sulfides, metal carbides, metal salts, silicon-based materials, carbon-based materials, metal organic frameworks, semiconductors, sulfur, fillers, surfactants, thermal control elements, fibers and foam reinforcements.

27. The method according to any one of embodiments 17 to 26, wherein the drying according to step d) is carried out by converting the liquid contained in the gel into a gaseous state at a temperature and a pressure below the critical temperature and the critical pressure of the liquid contained in the gel.

28. The method according to any one of embodiments 17 to 26, wherein the drying according to step d) is carried out under supercritical conditions.

29. A porous material obtained or obtainable by the method according to any one of embodiments 17 to 28.

30. The porous material according to embodiment 29, wherein the porous material has a specific surface area of 200 to 800 m ² /g, determined using the BET theory according to DIN 66134:1998-0, and a pore volume of 2.1 to 9.5 cm ³ /g for pore diameters <150 nm.

31. The porous material according to embodiment 29 or 30, wherein the content of volatile organic compounds (VOC) in the porous material is less than 50% of the content of volatile organic compounds (VOC) in the raw material used in the method.

32. Use of the porous material according to any one of embodiments 29 to 31 or the porous material obtained or obtainable by the method according to any one of embodiments 17 to 28 as a thermal insulation material, as a carrier material for loading and releasing active substances, for battery applications, for electrode materials in batteries, fuel cells or electrolysis, for catalysis, for capacitors, for consumer electronics, for building and construction applications, for home appliance applications, for temperature-controlled logistics applications, for vacuum insulation applications, for clothing applications, for food applications, for cosmetic applications, for biomedical applications, for agricultural applications, for consumer applications, for packaging applications or for pharmaceutical applications.

33. A method for preparing a porous material, comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound (C1) selected from water-soluble lignin biopolymers and silicon dioxide and at least one water-soluble polysaccharide having carboxylic acid groups as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c),

Wherein compound (C2) is selected from alginate, pectin, modified cellulose, xanthan gum, hyaluronic acid or modified starch.

34. A method according to embodiment 33, wherein compound (C2) is selected from alginates.

35. The method according to any one of embodiments 33 or 34, wherein the mixture (M1) comprises the compound (C1) in an amount of 0.1% to 50% by weight, based on the weight of the mixture (M1).

36. The method according to any one of embodiments 33 to 35, wherein the mixture (M1) comprises compound (C1) and compound (C2) in a ratio of 55:45 to 98:2.

37. The method according to any one of embodiments 33 to 36, wherein the pH value of the mixture (M1) is 7 to 14 or 8 to 14.

38. The method according to any one of embodiments 33 to 37, wherein the polyvalent metal ion is a divalent metal ion, in particular a divalent metal ion selected from alkaline earth metal ions, or wherein the polyvalent metal ion is a trivalent metal ion selected from aluminum ions and iron (III) ions.

39. The method according to any one of embodiments 33 to 38, wherein the method comprises one or more further modification steps of the dried gel, in particular wherein the modification step is selected from a forming step, a compression step, a lamination step, a post-drying step, a hydrophobization step and a carbonization step.

40. The process according to any one of embodiments 33 to 39, wherein the solvent (L) used in step c) is selected from C1 to C6 alcohols and C1 to C6 ketones, and mixtures thereof.

41. The process according to any one of embodiments 33 to 40, wherein a water-insoluble solid (S) is contacted with the mixture (M1).

42. A method according to any one of embodiments 33 to 41, wherein a compound (C) is added to the mixture (M1), wherein the compound (C) is selected from pigments, sunscreens, flame retardants, catalytic materials, metals, metal oxides, metal sulfides, metal carbides, metal salts, silicon-based materials, carbon-based materials, metal organic frameworks, semiconductors, sulfur, fillers, surfactants, thermal control elements, fibers and foam reinforcements.

43. The method according to any one of embodiments 33 to 42, wherein the drying according to step d) is carried out by converting the liquid contained in the gel into a gaseous state at a temperature and a pressure below the critical temperature and the critical pressure of the liquid contained in the gel.

44. The method according to any one of embodiments 33 to 42, wherein the drying according to step d) is carried out under supercritical conditions.

45. A porous material obtained or obtainable by a method according to any one of embodiments 33 to 44.

46. The porous material according to embodiment 45, wherein the specific surface area of the porous material is 200 to 800 m ² /g, determined using the BET theory according to DIN 66134:1998-0, and the pore volume is 2.1 to 9.5 cm ³ /g for pore diameters <150 nm.

47. The porous material according to embodiment 45 or 46, wherein the content of volatile organic compounds (VOC) in the porous material is less than 50% of the content of volatile organic compounds (VOC) in the raw material used in the method.

48. Use of the porous material according to any one of embodiments 45 to 47 or the porous material obtained or obtainable by the method according to any one of embodiments 33 to 44 as a thermal insulation material, as a carrier material for loading and releasing active substances, for battery applications, for electrode materials in batteries, fuel cells or electrolysis, for catalysis, for capacitors, for consumer electronics, for building and construction applications, for home appliance applications, for temperature-controlled logistics applications, for vacuum insulation applications, for clothing applications, for food applications, for cosmetic applications, for biomedical applications, for agricultural applications, for consumer applications, for packaging applications or for pharmaceutical applications.

49. A method for preparing a porous material, comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound (C1) selected from the group consisting of lignin biopolymers and silicon dioxide, and at least one water-soluble polysaccharide having carboxylic acid groups as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of divalent or trivalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c),

Wherein compound (C2) is selected from alginate, pectin, modified cellulose, xanthan gum, hyaluronic acid or modified starch.

50. A method for preparing a porous material, comprising at least the following steps:

a) providing a mixture (M1) comprising water, at least one compound (C1) selected from lignin biopolymers and silicon dioxide, and at least one component (C2) selected from alginates,

b) contacting the mixture (M1) with an aqueous solution of divalent or trivalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c).

51. A method for preparing a porous material, comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound selected from bio-based polymers (C1), and at least one polyionic biopolymer as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c).

52. The method according to embodiment 51, wherein compound (C1) is a protein, preferably a protein selected from the group consisting of whey protein, pea protein, yeast protein and potato glycoprotein, in particular a protein selected from the group consisting of whey protein.

53. A method for preparing a porous material, comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound selected from bio-based polymers (C1), and at least one polyionic biopolymer as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c).

Wherein compound (C1) is a protein, preferably a protein selected from whey protein, pea protein, yeast protein and potato glycoprotein, in particular a protein selected from whey protein.

54. The method according to any one of embodiments 51 to 53, wherein compound (C2) is a polyanionic biopolymer, preferably a polyionic biopolymer selected from alginate, pectin and modified cellulose.

55. A method for preparing a porous material, comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound selected from bio-based polymers (C1), and at least one polyionic biopolymer as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c),

wherein compound (C1) is a protein, preferably a protein selected from whey protein, pea protein, yeast protein and potato glycoprotein, in particular a protein selected from whey protein, and wherein compound (C2) is a polyanionic biopolymer, preferably a polyionic biopolymer selected from alginate, pectin and modified cellulose.

56. The method according to any one of embodiments 51 to 55, wherein the mixture (M1) comprises the compound (C1) in an amount of 0.1 wt.-% to 50 wt.-%, based on the weight of the mixture (M1).

57. The method according to any one of embodiments 51 to 56, wherein the mixture (M1) comprises compound (C1) and compound (C2) in a ratio of 55:45 to 98:2.

58. The method according to any one of embodiments 51 to 57, wherein the method comprises one or more further modification steps of the dried gel, in particular wherein the modification step is selected from a forming step, a compression step, a lamination step, a post-drying step, a hydrophobization step and a carbonization step.

59. The process according to any one of embodiments 51 to 58, wherein the solvent (L) used in step c) is selected from C1 to C6 alcohols and C1 to C6 ketones, and mixtures thereof.

60. The process according to any one of embodiments 51 to 59, wherein a water-insoluble solid (S) is contacted with the mixture (M1).

61. A method according to any one of embodiments 51 to 60, wherein a compound (C) is added to the mixture (M1), wherein the compound (C) is selected from pigments, sunscreens, flame retardants, catalytic materials, metals, metal oxides, metal sulfides, metal carbides, metal salts, silicon-based materials, carbon-based materials, metal organic frameworks, semiconductors, sulfur, fillers, surfactants, thermal control elements, fibers and foam reinforcements.

62. A porous material obtained or obtainable by a method according to any one of embodiments 51 to 61.

63. A porous material obtained or obtained by a method comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound selected from bio-based polymers (C1), and at least one polyionic biopolymer as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c).

64. A porous material obtained or obtained by a method comprising at least the following steps:

a) providing a mixture (M1) comprising at least one compound selected from bio-based polymers (C1), and at least one polyionic biopolymer as component (C2) and water,

b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A),

c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B),

d) drying the gel (B) obtained in step c),

wherein compound (C1) is a protein, preferably a protein selected from whey protein, pea protein, yeast protein and potato glycoprotein, in particular a protein selected from whey protein, and wherein compound (C2) is a polyanionic biopolymer, preferably a polyionic biopolymer selected from alginate, pectin and modified cellulose.

65. The porous material according to any one of embodiments 62 to 64, wherein the porous material has a specific surface area of 200 to 800 m ² /g, determined using BET theory according to DIN 66134:1998-0, and a pore volume of 2.1 to 9.5 cm ³ /g for pore diameters <150 nm.

66. The porous material according to any one of embodiments 60 to 65, wherein the content of volatile organic compounds (VOC) in the porous material is less than 50% of the content of volatile organic compounds (VOC) in the feedstock used in the method.

67. The porous material according to any one of embodiments 62 to 66, wherein the porous material is in the form of beads and preferably has an average diameter of 0.5 mm to 3 mm.

68. Use of the porous material according to any one of embodiments 62 to 67 or a porous material obtained or obtainable by the method according to any one of embodiments 51 to 61 as a support material or adsorbent.

69. Use of the porous material according to any one of embodiments 62 to 67 or the porous material obtained or obtainable by the method according to any one of embodiments 51 to 61 as a thermal insulation material, as a carrier material for loading and releasing active substances, for battery applications, for electrode materials in batteries, fuel cells or electrolysis, for catalysis, for capacitors, for consumer electronics, for building and construction applications, for home and commercial appliance applications, for temperature-controlled logistics applications, for vacuum insulation applications, for clothing applications, for food applications, for cosmetic applications, for biomedical applications, for agricultural applications, for consumer applications, for packaging applications or for pharmaceutical applications.

The present invention will be described below using examples.

Example

1. Preparation Example

Raw materials: kraft lignin (UPM), sodium hydroxide (NaOH, Sigma Aldrich), calcium chloride (CaCl ₂ , Sigma Aldrich), pure ethanol (Sigma Aldrich), sodium alginate (Hydagen, BASF), hexamethyldisilazane (HMDZ, Sigma Aldrich), silica sol SM30 (Sigma Aldrich), whey protein (AgropureIngredients), xanthan gum (Sigma Aldrich), microcrystalline cellulose (MCC, Sigma Aldrich), sodium caseinate (Sigma Aldrich), tannic acid (Sigma Aldrich), potato starch (Sigma Aldrich), gelatin (SigmaAldrich), pea protein isolate (Elmsland group), potato protein isolate (Avebe), Augeo (Solvay)

1.1 Whey protein/alginate hybrid aerogel

Solution 1: Whey protein was dissolved in water at 20 wt% at room temperature.

Solution 2: Sodium alginate was dissolved in water at 2 wt % at room temperature.

Solution 3: Prepare _CaCl2 aqueous solution (20 g/L) at room temperature.

Solutions 1 and 2 were combined at a whey protein to sodium alginate weight ratio of 95:5 for a total concentration of 15 wt %. Solution 4 was obtained by adjusting the pH to ~7 with NaOH.

Solution 4 was added dropwise to solution 3 (10x volume) using a pipette. Hydrogel particles formed and settled to the bottom of solution 3.

The hydrogel particles were soaked in ethanol (93%, 10x volume) for 5 min. A final solvent exchange step was performed by soaking the gel particles from the previous step in pure ethanol (10x volume) for 5 min to obtain alcohol gel particles (final solvent concentration 94-98%).

The alcohol gel was dried with supercritical carbon dioxide at 60 °C and 120 bar for 1 h to obtain whey protein/alginate hybrid aerogel particles.

The bulk density of the aerogel particles is -150 g/l.

The surface area of the aerogel particles was determined to be 139 m ² /g.

1.2 Hybrid aerogels containing various biopolymers

Solution 1: Microcrystalline cellulose, sodium caseinate, tannic acid, potato starch or gelatin were mixed with 2 wt% sodium alginate solution to obtain various solutions with concentrations and weight ratios as shown in Table 2. For potato starch, the dispersion of potato starch was heated to 90°C for dissolution before mixing. For gelatin, the gelatin dispersion was heated to 80°C for dissolution before mixing. For microcrystalline cellulose (MCC), 6 g of MCC was added to 94 g of 8 wt% NaOH at -8°C with stirring, and the resulting mixture was allowed to stand at 4°C for 24 h. 40 wt% NaOH was added to various solutions until the pH values shown in Table 2 were obtained.

Solution 2: Prepare _CaCl2 aqueous solution (10 g/L) at room temperature and adjust to pH 10 with 1 M NaOH.

Solution 1 was added dropwise to solution 2 (10x volume) using a pipette. Hydrogel particles formed and settled to the bottom of solution 2.

The hydrogel particles were soaked in ethanol (93%, 10x volume) for 5 min. A final solvent exchange step was performed by soaking the gel particles from the previous step in pure ethanol (10x volume) for 5 min to obtain alcohol gel particles (final solvent concentration 94-98%).

The alcohol gel was dried with supercritical carbon dioxide at 60 °C and 120 bar for 1 h to obtain hydrophilic hybrid aerogel particles, whose bulk density and surface area are shown in Table 2.

For hydrophobization, 50 mL of hydrophilic aerogel particles were placed in a filter bag in a 2 L reactor. Similarly, 50 mL of HMDZ was placed in the reactor in a small open container. The reactor was closed and heated to 115 °C. After 20 hours, the reactor was cooled to room temperature and the hydrophobic aerogel particles with a surface area shown in Table 1 were taken out of the reactor.

Table 1

2. Preparation of Hybrid Aerogels

Biopolymer A and biopolymer B were dissolved in water using a stirrer at a target ratio and weight concentration as shown in Table 1. At room temperature, the obtained solution was dripped into a 50 g/l multivalent metal salt solution at twice the volume using a syringe needle connected to a pump and a reservoir to obtain hydrogel beads (the syringe needle diameter was adjusted to a hydrogel particle diameter d of 2 mm). The obtained hydrogel beads were cured in a gelling bath for 2 h at room temperature. The shape of the hydrogel beads was qualitatively evaluated to evaluate their roundness and gel integrity. The diameter d ₀ of 10 hydrogel beads was measured and averaged. The hydrogel beads were washed with water and the water was continuously exchanged for >98% ethanol in 3 steps to obtain alcohol gel beads. The alcohol gel beads were dried using supercritical CO ₂ to obtain aerogel beads. The diameter d _e of 10 aerogel beads was measured, averaged and the shrinkage was calculated.

The beads were tested for stability and loading. The results are shown in Table 2a and Table 2b.

Table 2a

Table 2b

3. Method of use

3.1 The pore volume was measured using a Quantachrome Instruments Nova 4000e pore size analyzer according to DIN 66134:1998-02. Approximately 15-20 mg of sample was separated from the original sample and placed in a measuring glass cell. The sample was degassed at 50 mm Hg vacuum and 60°C for 15 h to remove any adsorbed components on the sample. The sample was weighed again before surface area and pore size analysis.

3.2 Surface area measurement: The specific surface area was determined by the Brunauer-Emmet-Teller (BET) method using low temperature nitrogen adsorption analysis (at the boiling point of nitrogen, 77 K) within the IUPAC recommended P/P0 range (0.05-0.30). A linear plot of 1/((w.(P0/P-1))) versus P/P0 was generated with a correlation coefficient (r) greater than 0.999.

3.3 Humidity test: 5 ml of aerogel beads were placed in a petri dish. The diameters _d0 of 10 aerogel beads were measured and averaged. The aerogel beads were exposed to a relative humidity of 60% at 30°C for 48 hours. The diameters d _e of 10 aerogel beads were measured, averaged and the shrinkage was calculated.

3.4 Liquid loading: Place 5 ml of aerogel beads in a glass vial. Measure the diameter _d0 of 10 beads and take the average. Add the liquid or liquefied organic solvent or oil onto the beads in 3-4 drops in steps, gently agitate the beads after every few drops to disperse the active, and stop adding once supernatant is observed. Measure the diameter d _e of 10 loaded beads, take the average and calculate the shrinkage. Evaluate the mechanical elasticity by compression between two fingers.

The shrinkage was calculated as S = ( _de - _do )/ _do , where _do is the initial bead diameter and _de is the final bead diameter.

References

Journal of Supercritical Fluids 2015,105,1-8

US20190329208A1

Grishechko,L.et al.Industrial Crops and Products,41(2013)347-355

Partap et al. (2006, "Supercritical Carbon Dioxide in Water" Emulsion-Templated Synthesis of Porous Calcium Alginate Hydrogels. Advanced Materials18,501 50

WO 2016032733A2

WO 2019167013A1

EP 3741794A1

EP 2663395B1

CN 114958480A

WO 2018056652A

WO 2017023702A1

Budtova et al.(Cellulose 2019,26,81-121(10.1007/s10570-018-2189-1CN105601983B

WO 2019190379A1

WO 96/25950 A1

WO 9501165A1

WO 2009062975A1

WO 02051389A2

WO 2009/027310

Robitzer et al.,2008,Langmuir,24(21),12547-12552

Claims (15)

1. A method for preparing a porous material, comprising at least the following steps: a) providing a mixture (M1) comprising at least one compound selected from bio-based polymers (C1), and at least one polyionic biopolymer as component (C2) and water, b) contacting the mixture (M1) with an aqueous solution of polyvalent metal ions to prepare a gel (A), c) exposing the gel (A) obtained in step b) to a water-miscible solvent (L) to obtain a gel (B), d) drying the gel (B) obtained in step c). 2. The method according to claim 1, wherein compound (C1) is a protein, preferably a protein selected from the group consisting of whey protein, pea protein, yeast protein and potato glycoprotein, in particular a protein selected from the group consisting of whey protein. 3. The method according to claim 1 or 2, wherein compound (C2) is a polyanionic biopolymer, preferably a polyionic biopolymer selected from alginate, pectin and modified cellulose. 4 . The process according to claim 1 , wherein the mixture (M1) comprises the compound (C1) in an amount of 0.1% to 50% by weight, based on the weight of the mixture (M1). 5. The method according to any one of claims 1 to 4, wherein the mixture (M1) comprises compound (C1) and compound (C2) in a ratio of 55:45 to 98:2. 6. The method according to any one of claims 1 to 5, wherein the method comprises one or more further modification steps of the dried gel, in particular wherein the modification step is selected from a shaping step, a compression step, a lamination step, a post-drying step, a hydrophobizing step and a carbonizing step. 7. The process according to any one of claims 1 to 6, wherein the solvent (L) used in step c) is selected from C1 to C6 alcohols and C1 to C6 ketones and mixtures thereof. 8. The process according to any one of claims 1 to 7, wherein a water-insoluble solid (S) is contacted with the mixture (M1). 9. The process according to any one of claims 1 to 8, wherein a compound (C) is added to the mixture (M1), the compound (C) being selected from the group consisting of pigments, sunscreens, flame retardants, catalytic materials, metals, metal oxides, metal sulfides, metal carbides, metal salts, silicon-based materials, carbon-based materials, metal organic frameworks, semiconductors, sulfur, fillers, surface-active substances, thermal control elements, fibers and foam reinforcements. 10. A porous material obtained or obtainable by a method according to any one of claims 1 to 9. The porous material according to claim 10 , wherein the porous material has a specific surface area of 200 to 800 m ² /g, determined using the BET theory according to DIN 66134:1998-0, and a pore volume of 2.1 to 9.5 cm ³ /g for pore diameters <150 nm. 12. The porous material according to claim 10 or 11, wherein the volatile organic compound (VOC) content in the porous material is less than 50% of the volatile organic compound (VOC) content in the feedstock used in the process. 13. The porous material according to any one of claims 10 to 12, wherein the porous material is in the form of beads and preferably has an average diameter of 0.5 mm to 3 mm. 14. Use of a porous material according to any one of claims 10 to 13 or a porous material obtained or obtainable by a method according to any one of claims 1 to 9 as a support material or adsorbent. 15. Use of the porous material according to any one of claims 10 to 13 or the porous material obtained or obtainable by the method according to any one of claims 1 to 9 as a thermal insulation material, as a carrier material for loading and releasing active substances, for battery applications, for electrode materials in batteries, fuel cells or electrolysis, for catalysis, for capacitors, for consumer electronics, for building and construction applications, for home and commercial appliance applications, for temperature-controlled logistics applications, for vacuum insulation applications, for clothing applications, for food applications, for cosmetic applications, for biomedical applications, for agricultural applications, for consumer applications, for packaging applications or for pharmaceutical applications.