Porous material based on colloidal particles

Abstract

The invention relates to a solid porous material characterised in that it comprises: - a first population of particles consisting of nanoparticles smaller than 300 nm in size; - at least one other population of particles comprising one or more components distributed according to one or more particle sizes, the other population of particles representing from 20% to 80% of the total volume of the material, wherein the first population of particles represents from 25% to 85% of the volume of the material present between the particles of the other population of particles. The invention also relates to a method for producing a porous material, characterised in that it consists in adding porous particles to a colloidal sol comprising colloidal particles, said porous particles being wettable by the liquid portion of the sol and having pores and a pore network that are sufficiently fine to prevent them from being penetrated by the sol particles, which are expelled therefrom and concentrate in the liquid medium outside the particles, such that the concentration of colloidal particles in the suspension external to the particles is sufficient to allow drying to be carried out through to the drying phase in which the shrinkage stabilises.

Description

[0001] POROUS MATERIAL BASED ON COLLOIDAL PARTICLES

[0002] FIELD OF THE INVENTION

[0003] The invention relates to a porous material comprising solid particles dispersed in a matrix of agglomerated colloidal particles and a method of preparing the same.

[0004] BACKGROUND OF THE INVENTION

[0005] Porous materials made of nanoparticles agglomerated to form solid clusters with macropores, mesopores, and micropores in their structure are known to very often present problems of cracks or microcracks. These cracks or microcracks generally appear in their preparation process at the time of drying. The large dimensional variations, or shrinkages, observed during their drying, considerably limit their applications. Indeed, it is difficult with current materials to repeatedly produce materials with high porosity and high specific surface area with precise dimensions.

[0006] The drying curve of a colloidal material suspended in a solvent, or sol, shows different phases, characterizing the behavior of the material. During a first drying phase, the volume of the suspension decreases, and the concentration of the sol increases in the liquid phase. During a second drying phase, the volume decreases much less, because the concentration reached by the sol is so high that support forces develop between the colloidal particles very close to each other. These mechanical and chemical forces (Van der Waals forces for example) prevent the structure from collapsing appreciably, and the volume of the material becomes practically constant during the continuation of drying. Reference is made in particular to the following reference (1) "Sol Gel Science" C. Jeffrey Brinker, Georges W Scherrer, Academie Press, 1990. A detailed examination and presentation of this phenomenon is described in chapter 8, Drying, pp. 453 to 509.Figure 7 of this chapter and the related publication (2) (T. Kawaguchi, J. lura, N. Taneda, H. Hishikura, Y. Kokubu, J. Non-Cryst. Solids, 82 (1986) 1816-1821) are particularly exemplary. During the terminal phase of drying, considerable capillary forces that can amount to several hundred bar of pressure develop between the particles due to the small size of the pores that separate them, and the wettability of the particles by the liquid phase. These shrinkages produce microscopic and macroscopic cracks in the material that can lead to its fragmentation. These capillary forces can produce an additional shrinkage of the material during drying, although less marked than during the first phase, and their disappearance can, on the contrary, produce a slight expansion at the end of drying.These capillary forces occur over large lengths relative to the particle size, meaning that these forces cannot be transferred to any microscopic medium. There is no current solution to these various problems, and particularly to the last of them.

[0007] There remains a need to provide a process for producing a porous material that solves these problems and therefore to propose a porous material that does not present fracturing problems.

[0008] BRIEF DESCRIPTION OF THE INVENTION

[0009] The invention relates to a solid porous material characterized in that it comprises:

[0010] - a first population of particles made up of nanoparticles smaller than 300 nm;

[0011] - at least one other population of solid particles comprising one or more components distributed according to one or more particle sizes, the other population of solid particles representing from 20% to 80% of the total volume of the material, in which the first population of particles represents from 25% to 85% of the volume of the material present between the particles of the other population of particles.

[0012] Advantageously, the other population of solid particles has a low or microscopic number average diameter, preferably less than 500 pm, preferably less than 100 pm, even more preferably less than 30 pm.

[0013] Particularly preferably, the other population of solid particles has a number average diameter of less than 3 pm.

[0014] In one embodiment of the invention, the method of manufacturing the material according to the invention comprises the following steps:

[0015] (a) providing a sol consisting of particles of size d1, in particular nanoparticles of size d1, concentrated at more than 40%, and preferably at more than 45% by volume of solid particles;

[0016] (b) supply of solid particles

[0017] (d) adding said solid particles to the soil;

[0018] (e) drying.

[0019] Advantageously, the first population is part of a network enclosing in a solid continuum at least one other population of particles of the material.

[0020] Advantageously, the first population of particles represents more than 45% of the volume of the material present between the particles of at least one other population of particles, advantageously more than 50%, even more advantageously more than 55%, and more preferably more than 60% of this volume. Advantageously, the nanoparticles of the first population have a size greater than one time, preferably greater than two times, even more preferably greater than ten times the average diameter of the pores of at least one other population of the material.

[0021] Advantageously, the first population of particles results from a sol based on aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, rare earth oxide such as yttrium, cerium or lanthanum, boron oxide, iron oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, germanium oxide, phosphorus oxide, lithium oxide, potassium oxide, sodium oxide, niobium oxide, copper oxide or a mixture thereof.

[0022] Advantageously, the first population of particles is made up of organic nanoparticles.

[0023] Advantageously, the first population of particles consists of organometallic nanoparticles.

[0024] Advantageously, the first population of particles results from a sol based on aluminum oxide or silicon oxide.

[0025] Advantageously, at least one other population of particles consists of particles of a ceramic such as in particular silica, alumina, zirconium oxide, titanium oxide, an aluminosilicate, an organic or mineral binder such as cellulose, plaster, metal silicates, or a ferrous metal such as iron or its alloys, steel, a non-ferrous metal or at least one of their alloys, one or a plurality of polymers such as, for example, polyamides, polyimides, acrylic polymers, polyesters, polyurethanes, halogenated polymers, natural polymers, elastomers.

[0026] Advantageously at least one other population of particles consists of a solid polymer.

[0027] Advantageously, in this case, the second population will be considered as composed of a single crosslinked molecule or of an assembly of distinct individual polymeric elements, constituted by distinct polymeric chains.

[0028] Advantageously, said polymer population extends as a continuum between the first population of nanometric particles. Advantageously, a solid porous material according to the invention is characterized in that it comprises:

[0029] - a first population of particles made up of nanoparticles smaller than 300 nm;

[0030] - a second population of particles consisting of porous particles having a porosity ranging from 10% to 90% by volume, the second population of particles representing from 20% to 80% of the total volume of the material,

[0031] Advantageously, the second population of particles consists of particles of silica gel, activated alumina, silico aluminate, porous metal, glass, zeolites, carbon black, activated carbon, pumice stone, kieselgur, or porous organic or organometallic polymers.

[0032] Advantageously, the second population of particles is physically or chemically reactive and comprises or consists of a mineral filler, serving as an agent in a separation technique such as a stationary phase for chromatography, as a catalyst, or as a filler consumable by a chemical reaction.

[0033] Advantageously, the second population of particles is physically or chemically reactive and comprises or consists of an organic or biological filler serving as an agent of a chemical or biological reaction, such as an ion exchanger, a protein, a fragment of DNA or RNA or an immobilized enzyme.

[0034] Advantageously, the material also comprises a filler of fibers, microfibers or nanofibers.

[0035] Advantageously, the material comprises a proportion of mesopores between 2 and 50 nanometers greater than 90% by volume.

[0036] Advantageously, the material obtained serves as an intermediary and is transformed to eliminate any trace of porosity in it by sintering or by the polymerization of a precursor present in situ.

[0037] Advantageously, the material serves as a matrix and contains preforms or templates subsequently partially or totally removed by melting, vaporization, freeze-drying, dissolution, chemical attack, hydrolysis, pyrolysis or oxidation so as to leave their imprint in the matrix. Advantageously, the material is obtained by injecting a precursor into a mold, solidifying and drying.

[0038] The invention also relates to a method for preparing a porous material comprising the following steps:

[0039] (a) providing a sol consisting of nanoparticles of size less than 300 nm dispersed in a liquid;

[0040] (b) providing porous solid particles having a porosity ranging from 10% to 90% by volume, the pores of which have a size that does not allow soil nanoparticles to penetrate therein, the porous solid particles being wettable by soil liquid;

[0041] (c) addition of the porous solid particles to the soil so as to achieve a volume fraction of nanoparticles in the liquid greater than 20%;

[0042] (d) drying.

[0043] Advantageously, the sol dispersion liquid comprises an organic solvent such as in particular an alcohol, a polyol, a polyether such as polyethylene glycol or propylene glycol, an amino solvent.

[0044] Advantageously, the organic solvent comprises a polymerizable or crosslinkable body such as in particular an acrylate or a methacrylate, preferably hydroxyethyl acrylate or methacrylate, glyceryl monoacrylate or monomethacrylate, glycidyl acrylate or methacrylate, methyl methacrylate, 2- (Dimethylamino)ethyl methacrylate, 2- (Diethylamino)ethyl methacrylate, 2- (Diisopropylamino)ethyl methacrylate, 2- (ferf-Butylamino)ethyl methacrylate, hydroxypropylamine methacrylate, hydroxypropyl dimethylamine methacrylate, / V- [3-dimethylamino)propyl]methacrylamide, etc.

[0045] Advantageously, the polymerizable body is polymerized, ionically in solution, thermally or photochemically using appropriate initiators.

[0046] Advantageously, the polymerization is carried out photochemically so as to create a flat or three-dimensional structure such as a photochemical resist or microscopic and macroscopic elements.

[0047] Advantageously, the resulting body, polymerized and transformed into threads, is used to carry out additive 3D printing. Advantageously, the polymerized body is eliminated by dissolution, vaporization, chemical attack, hydrolysis, or pyrolysis and oxidation.

[0048] Advantageously, the method according to the invention comprises an additional step of reinforcement by sintering or by adding a layer of a third solid material on and / or between the particles constituting it.

[0049] Advantageously, this third solid material is a layer of amorphous silica obtained by a redissolution / redeposition phenomenon known as Ostwald ripening, or by precipitation of amorphous silica from a mineral precursor such as an acidified soluble silicate or a hydrolyzed alkoxysilane.

[0050] Advantageously, the method according to the invention comprises between steps (c) and (d) the steps of action of a binding agent initiating the formation of a gel from the sol and of freezing of the sol by an increase in temperature.

[0051] Advantageously, the binding agent initiating the formation of the gel is a calcium salt, an aluminum salt, or a salified or non-salified polyamine.

[0052] Advantageously the porous solid particles consist of a silica gel and the sol is a silica sol.

[0053] Advantageously, the porous solid particles are made of activated alumina and the soil is a boehmite soil.

[0054] Advantageously, the material according to the invention includes preforms or templates subsequently partially or totally eliminated by melting, vaporization, freeze-drying, dissolution, chemical attack, hydrolysis, pyrolysis or oxidation so as to leave their imprint in the matrix.

[0055] Advantageously, the method of manufacturing the material according to the invention comprises a step of injecting one of its fluid precursors.

[0056] Advantageously, the method of manufacturing the material according to the invention comprises a step of extruding one of its fluid precursors.

[0057] Advantageously, the method for manufacturing the material according to the invention comprises a step of machining said material or one of its solid precursors. In other embodiments, the method for manufacturing a composite material comprises at least the following steps:

[0058] (a) providing a sol consisting of a first population of solid particles of a first size (d1), in particular nanoparticles of said first size (d1), dispersed in an aqueous solvent;

[0059] (a') transferring said sol into a second organic solvent miscible with the first solvent;

[0060] (b) provision of a second population of solid particles

[0061] (c) adding said second population of solid particles to the soil;

[0062] (d) drying.

[0063] According to these embodiments, the invention has other advantageous but optional characteristics, possibly taken in combination: the second population of solid particles has pores of a second size (d2) less than ten times the first size; the sol of solid particles of size (d1) provided in step (a) is concentrated to more than 40%, and preferably 45%, by volume of solid particles; at the end of step (c), the second population of particles represents from 20% to 80% of the total volume of the material and the first population of particles represents from 25% to 85% of the volume of the material present between the porous particles of the second population of particles; the second population of solid particles comprises at least two different types of particles, in particular, the at least two different types of particles of the second population have at least two different particle sizes;the second solvent is selected from an alcohol, a polyol, a polyether such as polyethylene glycol or propylene glycol, or an amine solvent. wherein the second solvent comprises a monomer, an oligomer or a subsequently polymerized macromolecule;in particular, the organic solvent comprises an acrylate or a methacrylate, preferably hydroxyethyl acrylate or methacrylate, glyceryl monoacrylate or monomethacrylate, glycidyl acrylate or methacrylate, methyl methacrylate, 2-(Dimethylamino)ethyl methacrylate, 2-(Diethylamino)ethyl methacrylate, 2-(Diisopropylamino)ethyl methacrylate, 2-(tert-Butylamino)ethyl methacrylate, hydroxypropylamine methacrylate, hydroxypropyl dimethylamine methacrylate, N-[3-dimethylamino)propyl]methacrylamide, and even more preferably an acrylate or a methacrylate, such as hydroxyethyl acrylate or methacrylate, glyceryl monoacrylate or monomethacrylate, glycidyl acrylate or methacrylate, methyl methacrylate;the method comprises a step of polymerizing said polymerizable or crosslinkable body included in the organic solvent, this polymerization being able to be carried out thermally or photochemically; the nanoparticles of the first population have a size d1 greater than one time, preferably greater than two times, even more preferably greater than ten times the average pore diameter of the second population of particles; the second population of solid particles has a pore volume representing at least 10% of the volume of the particles; the sol comprises colloidal silica; the second population of particles comprises a porous silica gel; the method further comprises the following steps independent of each other, before or after step (d): o adding to the sol at least one adjuvant and / or at least one binding agent; o surface treatment; o injection and / or extrusion of the material; o machining of said material.;

[0064] The invention is also a solid porous material characterized in that it comprises:

[0065] - a first population of particles consisting of nanoparticles of size less than 300 nm having a first pore size;

[0066] - a second population of particles consisting of porous particles having a porosity ranging from 10% to 90% by volume, the second population of particles representing from 20% to 80% of the total volume of the material, and whose average pore size is smaller than that of the first population; in which the first population is part of a network enclosing the second population in a solid continuum, and in which the first population of particles represents from 25% to 85% of the volume of the material present between the porous particles of the second population of particles.

[0067] BRIEF DESCRIPTION OF THE FIGURES

[0068] Other characteristics and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings, in which:

[0069] - Figure 1 illustrates example 7 by representing the ratio kg SiO2 / L water and the Vol eau resid as a function of the weight in SiO2 sol.

[0070] - Figures 2 and 3 are transmission electron microscopy photographs of the material obtained in Example 8, showing respectively the colloid part and the colloid part with silica gel. - Figures 4, 5 and 6 represent, respectively, the nitrogen adsorption / desorption isotherms, and the adsorption and desorption diameters of the material obtained in Example 8.

[0071] - Figures 7, 8 and 9 represent, respectively, the nitrogen adsorption / desorption isotherms, and the adsorption and desorption diameters of the material obtained in Example 9.

[0072] - Figure 10 is a transmission electron microscopy photograph of the material obtained in Example 9.

[0073] - Figures 11, 12 and 13 represent, respectively, the nitrogen adsorption / desorption isotherms, and the adsorption and desorption diameters of the material obtained in Example 10.

[0074] - Figures 14 and 15 represent the percentage of volume shrinkage of a soil sample as a function of its percentage weight loss.

[0075] - Figures 16 and 17 schematically illustrate the behavior of nanoparticle colloids after the addition of a porous solid as a function of the ratio between the sizes of the nanoparticles and the pores of the porous solid.

[0076] - figures 18 and 19 are microscope photos of channels and micrometric fluidic structures obtained with a variant of the process according to the invention using an organic solvent route.

[0077] DEFINITIONS

[0078] The term "sol" as used in this text refers to a dispersion of non-settleable particles in a liquid medium. These particles may correspond to agglomerates of particles, the agglomerates being able to be designated "secondary particles" as opposed to the particles constituting them designated "primary particles".

[0079] The term "nanoparticles" as used in this text means particles whose smallest dimension measures from 0.1 nanometers to 200 nanometers and whose aspect ratio is less than 10:1.

[0080] The term "size" as used in this text refers to the largest dimension of the particles. When the particles are spherical, the term size refers to the diameter of the particles.

[0081] In this text, and in accordance with usual conventions, the term "macroporosity" designates a pore size greater than 50 nanometers, the term "mesoporosity" designates a pore size between 2 and 50 nanometers and the term "microporosity" designates a pore size less than 2 nanometers. The pore sizes are measured with a mercury porosimeter for mesoporosity and macroporosity, and by nitrogen absorption following the BET method for microporosity. The pore size is defined by its volume average. In this text, the particles of the material distinct from the first population of particles will be defined in its most general terms as being "at least one other population of particles". When said particles are porous, they will be more simply referred to as "second population of particles" or "second population".

[0082] In order to define the volume of material particles distinct from the first population of particles, the volume of this distinct material in the dry, powdery state will be advantageously used, and as representing 60% of the compacted volume of said powder.

[0083] The size of the elementary grains of said powder will advantageously be measured by sieving or by optical or digital microscopy.

[0084] The average diameter of the particles or nanoparticles described in this text will advantageously be taken as their volume average diameter.

[0085] DETAILED DESCRIPTION OF THE INVENTION

[0086] The inventors have developed a solid porous material that does not present the fracturing problems mentioned above.

[0087] The solid porous material developed by the inventors comprises an agglomeration of at least two populations of intimately dispersed particles. The porous material is characterized in that it comprises:

[0088] - a first population of particles made up of nanoparticles smaller than 300 nm;

[0089] - at least one other population of particles comprising one or more components distributed according to one or more particle sizes, the other population of particles representing from 20% to 80% of the total volume of the material, in which the first population of particles represents from 25% to 85% of the volume of the material present between the particles of the other population of particles.

[0090] Advantageously, the first population is part of a network enclosing the other population of particles in a solid continuum.

[0091] Advantageously, the first population of particles represents more than 35% of the volume of the material present between the particles of at least one other population of particles, advantageously more than 40%, even more advantageously more than 50%, and more preferably more than 60% of this volume.

[0092] Advantageously, the first population of particles results from a mineral or inorganic soil based for example on aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, rare earth oxide such as yttrium, cerium or lanthanum, boron oxide, iron oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, germanium oxide, phosphorus oxide, lithium oxide, potassium oxide, sodium oxide, niobium oxide, copper oxide or a mixture thereof.

[0093] Advantageously, the first population of particles is made up of organic nanoparticles.

[0094] Advantageously, the first population of particles consists of organometallic nanoparticles.

[0095] Advantageously, the first population of particles results from a sol based on aluminum oxide or silicon oxide.

[0096] Advantageously, at least one other population of particles consists of particles of a ceramic such as in particular silica, alumina, zirconium oxide, titanium oxide, an aluminosilicate, an organic or mineral binder such as cellulose, plaster, metal silicates, or a ferrous metal such as iron or its alloys, steel, a non-ferrous metal or at least one of their alloys, one or a plurality of polymers such as, for example, polyamides, polyimides, acrylic polymers, polyesters, polyurethanes, halogenated polymers, natural polymers, elastomers.

[0097] Advantageously, this other population of particles has a diameter of less than 100 pm, advantageously less than 30 pm, even more advantageously less than 15 pm.

[0098] Particularly advantageously, this other population of particles has a diameter of less than 5 pm.

[0099] According to another embodiment of the invention, this other population of particles is made up of nanoparticles.

[0100] Advantageously, this other population of particles has a diameter less than 200 nm, advantageously less than 50 nm, even more advantageously less than 20 nm.

[0101] Advantageously, these nanoparticles are porous.

[0102] In one embodiment of the invention, the method of manufacturing the material according to the invention comprises the following steps:

[0103] (a) providing a sol consisting of particles of size d1, in particular nanoparticles of size d1, concentrated at more than 20%, and preferably at more than 40% by volume of solid particles; (b) providing solid particles

[0104] (d) adding said solid particles to the soil;

[0105] (e) drying.

[0106] The material according to the invention is in particular characterized by an absence of shrinkage during the transition between the wet material and the dried material.

[0107] In fact, this material according to the invention has such a volume proportion of the first population in the interstice separating the particles from the second population that the drying takes place on the flat and horizontal part of the drying curve presented in figure 14.

[0108] Figure 14 (Sol Gel Science, CJ Brinker, GW Sherrer, 1990), represents the percentage of volume shrinkage (V / Vo on the ordinate) of a soil sample as a function of its percentage weight loss (W / Wo on the abscissa).

[0109] It is noted that the shrinkage becomes negligible for soil G beyond a critical point located in this case for V / Vo = approximately 25%, and from V / Vo = 15% for soil H.

[0110] Figure 15 represents such behavior in a more synthetic way, with time on the abscissa and volume on the ordinate. Zone 1 represents the volume of the sample during the withdrawal phase in a dilute medium. Since the suspended solid particles are not very concentrated, the sample decreases in volume and gradually concentrates into solid. Zone 2 represents the volume of the sample during its stabilization phase. Since the solid particles become concentrated and form a compact residue, the volume no longer decreases during drying, despite the gigantic forces applied in this phase due to capillary forces and interfacial tension, of the order of several tons per cm 2 For example.

[0111] The invention consists precisely in drying a fluid mixture brought before its final molding beyond the critical point so as to fit the shape of the mold without dimensional variation, and in the new products obtained by this process.

[0112] The first population of particles is therefore concentrated, separating the second population of particles before the drying step. This can be done by any means, evaporation, extraction, membrane separation, etc.

[0113] This can be done before or after contact between the first and second populations.

[0114] Figures 16 and 17 schematically show behaviors according to one of the preferred variants of implementation of the invention.

[0115] In Figure 16, a colloid or sol of nanoparticles 3 of a first particle size dc1 is in the diluted state in a liquid 4. A solid 5 is added having pores of size dpi greater than dd. The colloid penetrates easily into the pores, and there is little or no difference in concentration of nanoparticles 3 between the medium internal to the pores, the suspension external to the porous solid and the initial colloid. The drying of such a material will be accompanied by shrinkage and instabilities (cracks).

[0116] On the other hand, in Figure 17, the starting colloid of nanoparticles 7 having a second, larger particle size dc2, the addition of a porous solid of pore sizes dp2 with dp2 smaller than dc2 leads to a selective suction of the liquid 4 in said pores, to the steric rejection of these nanoparticles by the pores of the solid, and therefore to a very rapid and powerful concentration of the nanoparticles 7 in the residual liquid external to the pores. By adjusting this effect, it is possible to sufficiently concentrate the nanoparticles so as to achieve a very compact packing of the solid in the medium, and drying in zone 2 of Figure 15, while maintaining sufficient fluidity and stability for practical implementation.

[0117] Tests are carried out using a silica colloid of 70 Angstroms with a spherical nanoparticle size. This colloid is placed in contact with identical quantities of silica gel of increasing pore sizes, 70, 100, 300 and 500 Angstroms. With silicas of pore sizes of 300 and 500 Angstroms, much larger than the size of the colloid, no change in the medium, either in viscosity or stability, is observed.

[0118] On the other hand, for pore sizes (70 and 100 nm) close to the size of the nanoparticles, the viscosity of the medium becomes high, and the medium becomes unstable after 24 hours, and freezes. The nanoparticles were rejected from the solid by steric exclusion and were highly concentrated in the medium external to the grains. In these cases, drying without shrinkage is observed.

[0119] Finally, two further tests were carried out. These last two specimens dried without shrinkage. The other two, however, showed shrinkage and cracks during drying. A detailed procedure corresponding to this study is provided in Example 25.

[0120] Advantageously, the solid porous material according to the invention is characterized in that it comprises:

[0121] - a first population of particles made up of nanoparticles smaller than 300 nm;

[0122] - a second population of particles consisting of porous particles having a porosity ranging from 10% to 90% by volume, the second population of particles representing from 20% to 80% of the total volume of the material,

[0123] Advantageously, the first population is part of a network enclosing the second population of porous particles in a solid continuum. Advantageously, the first population of particles represents more than 45% of the volume of the material present between the particles of the second population of porous particles, advantageously more than 50%, even more advantageously more than 55%, and more preferably more than 60% of this volume.

[0124] Advantageously, the nanoparticles of the first population have a size greater than one time, preferably greater than two times, even more preferably greater than ten times the average diameter of the pores of the second population of porous particles.

[0125] Advantageously, the first population of particles results from an ore or inorganic soil, and in particular based on aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, rare earth oxide such as yttrium, cerium or lanthanum, boron oxide, iron oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, germanium oxide, phosphorus oxide, lithium oxide, potassium oxide, sodium oxide, niobium oxide, copper oxide or a mixture thereof.

[0126] Advantageously, the first population of particles is made up of organic nanoparticles.

[0127] Advantageously, the first population of particles consists of organometallic nanoparticles.

[0128] Advantageously, the first population of particles results from a sol based on aluminum oxide or silicon oxide.

[0129] Advantageously, the second population of porous particles consists of particles of silica gel, activated alumina, silico aluminate, porous metal, glass, zeolites, carbon black, activated carbon, pumice stone, kieselgur, or porous organic or organometallic polymers.

[0130] Advantageously, the second population of porous particles is physically or chemically reactive and comprises or consists of a mineral filler, serving as an agent for a separation technique such as a stationary phase for chromatography, as a catalyst, or as a filler consumable by a chemical reaction.

[0131] Advantageously, the second population of porous particles is physically or chemically reactive and comprises or consists of an organic or biological filler serving as an agent of a chemical or biological reaction, such as an ion exchanger, a protein, a DNA or RNA fragment or an immobilized enzyme. Advantageously, the material further comprises a filler of fibers, microfibers or nanofibers.

[0132] Advantageously, the material comprises a proportion of mesopores between 2 and 50 nanometers greater than 90% by volume.

[0133] Advantageously, the material obtained serves as an intermediary and is transformed to eliminate any trace of porosity in it by sintering or by the polymerization of a precursor present in situ.

[0134] Advantageously, the material serves as a matrix and contains preforms or templates subsequently partially or totally eliminated by melting, vaporization, freeze-drying, dissolution, chemical attack, hydrolysis, pyrolysis or oxidation so as to leave their imprint in the matrix.

[0135] Advantageously, the material is obtained by injecting a precursor into a mold, solidifying and drying.

[0136] Advantageously, the process for preparing a porous material comprises the following steps:

[0137] (a) providing a sol consisting of nanoparticles of size less than 300 nm dispersed in a liquid;

[0138] (b) providing porous solid particles having a porosity ranging from 10% to 90% by volume, the pores of which have a size that does not allow soil nanoparticles to penetrate therein, the porous solid particles being wettable by soil liquid;

[0139] (c) addition of the porous solid particles to the soil so as to achieve a volume fraction of nanoparticles in the liquid greater than 20%;

[0140] (d) drying.

[0141] Advantageously, the sol dispersion liquid comprises an organic solvent such as in particular a polyol, a polyether such as polyethylene glycol or propylene glycol, an amino solvent.

[0142] In the very general case in which the sol is initially available or peptized in a first aqueous solution, it will be advantageous to transfer said sol into a non-aqueous or organic liquid miscible with the first aqueous solvent, by volatilizing the mixture so as to increase its proportion of non-aqueous or organic solvent. Advantageously in such a case the miscible non-aqueous or organic solvent will have an azeotrope with a low water content.

[0143] Low water content advantageously means a water content of less than 25% by weight, preferably less than 15% by weight.

[0144] Advantageously in such a case the miscible non-aqueous or organic solvent will have a boiling point higher than that of water.

[0145] Advantageously, the organic solvent comprises a polymerizable or crosslinkable body such as in particular an acrylate or a methacrylate, preferably hydroxyethyl acrylate or methacrylate, glyceryl monoacrylate or monomethacrylate, glycidyl acrylate or methacrylate, methyl methacrylate.

[0146] Advantageously, the polymerizable body is polymerized, ionically in solution, or thermally or photochemically using appropriate initiators.

[0147] Advantageously, the polymerization is carried out photochemically so as to create a flat or three-dimensional structure such as a photochemical resist or microscopic and macroscopic elements.

[0148] Advantageously, the body obtained after polymerization of the liquid and transformed into threads is used to carry out additive 3D printing.

[0149] Advantageously the polymerized body is removed by dissolution, vaporization, chemical attack, hydrolysis, or pyrolysis and oxidation.

[0150] Advantageously, the method according to the invention comprises an additional step of reinforcement by sintering or by adding a layer of a third solid material on and / or between the particles constituting it.

[0151] Advantageously, this third solid material is a layer of amorphous silica obtained by a redissolution / redeposition phenomenon known as Ostwald ripening, or by precipitation of amorphous silica from a mineral precursor such as an acidified soluble silicate or a hydrolyzed alkoxysilane.

[0152] Advantageously, the method according to the invention comprises, between steps (c) and (d), the steps of action of a binding agent initiating the formation of a gel from the sol and of freezing the sol by an increase in temperature. Advantageously, the binding agent initiating the formation of the gel is a calcium salt, an aluminum salt, or a salified or non-salified polyamine.

[0153] Advantageously, the second population of porous solid particles consists of a silica gel and the sol is a silica sol.

[0154] Advantageously, the second population of porous particles consists of activated alumina and the soil is a boehmite soil.

[0155] Advantageously, the material according to the invention includes preforms or templates subsequently partially or totally eliminated by melting, vaporization, freeze-drying, dissolution, chemical attack, hydrolysis, pyrolysis or oxidation so as to leave their imprint in the matrix.

[0156] Advantageously, the method of manufacturing the material according to the invention comprises a step of injecting one of its fluid precursors.

[0157] Advantageously, the method of manufacturing the material according to the invention comprises a step of extruding one of its fluid precursors.

[0158] Advantageously, the method of manufacturing the material according to the invention comprises a step of machining said material or one of its solid precursors.

[0159] The invention is also a solid porous material characterized in that it comprises:

[0160] - a first population of particles consisting of nanoparticles smaller than 300 nm;

[0161] - a second population of particles consisting of porous particles having a porosity ranging from 10% to 90% by volume, the second population of particles representing from 20% to 80% of the total volume of the material, and whose average pore size is smaller than that of the first population; in which the first population is part of a network enclosing the second population in a solid continuum, and in which the first population of particles represents from 25% to 85% of the volume of the material present between the porous particles of the second population of particles.

[0162] The porous material developed by the inventors can also and in particular be prepared by a process comprising the following steps: (a) providing a sol consisting of nanoparticles of size less than 300 nm dispersed in a liquid;

[0163] (b) providing porous solid particles having a porosity ranging from 10% to 90% by volume, the pores of which have a size that does not allow soil nanoparticles to penetrate therein, the porous solid particles being wettable by soil liquid;

[0164] (c) addition of the porous solid particles to the soil so as to achieve a volume fraction of nanoparticles in the liquid greater than 20%;

[0165] (d) drying.

[0166] This last proposed method makes it possible to address the aforementioned problems. It is thus proposed to add porous particles to a soil that are wettable by the liquid medium of the soil. The porous particles have pores of a sufficiently small size so that the soil nanoparticles cannot penetrate them. The soil nanoparticles then concentrate in the liquid medium outside the porous particles. Indeed, the pores of the porous particles absorb and fill with the liquid medium of the soil due to capillary forces. The concentration of nanoparticles then increases in the free liquid medium remaining outside the porous particles and between them.The concentration of nanoparticles in the liquid medium external to the porous particles is carried out within the framework of the method of the present invention so that this concentration is sufficient to allow the drying of the material to be carried out under conditions corresponding to the terminal part of drying or second phase previously mentioned. Thus, enough porous particles are added to a sufficiently concentrated sol so that the concentration of nanoparticles (colloidal particles) in the liquid remaining between the porous solid particles ends up being greater than or equal to the concentration of nanoparticles allowing the second drying phase to be reached during the drying of the material. The shrinkage stabilizes because the concentration reached by the sol is so high that support forces develop between the colloidal particles very close to each other during drying.On the other hand, the fineness of the porous solid particles and their volume content mean that the characteristic distance which characterizes the free length over which the soil must dry and solidify is reduced to the interstice between the nearby porous particles, that is to say to a few hundred microns, advantageously to a few tens of microns, and even more advantageously to a few microns or less.

[0167] The material, its components and the process of the invention may be as described in detail below. Process for preparing the porous material (aqueous solvent option)

[0168] Step (a): provision of the soil

[0169] The soil can be based on any compound that provides cohesion to the material.

[0170] The sol may be, but is not limited to, a silica sol, a boehmite sol, a macromolecular suspension, for example a colloidal suspension of a polymer, such as pectin (polysaccharide), a suspension of proteins, such as ovalbumin or gelatin, a suspension of high molecular weight carbohydrates, such as starch or cellulose, a suspension of colloidal metals, such as silver (Collargol) or gold, or copper, a micellar suspension, for example based on surface-active compounds (detergents), a colloidal suspension of an elastomer such as a latex or a suspension of carbon particles such as carbon nanotubes.

[0171] The soil may be based more particularly on a soil based on aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, rare earth oxide such as yttrium, cerium or lanthanum, boron oxide, iron oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, germanium oxide, phosphorus oxide, lithium oxide, potassium oxide, sodium oxide, niobium oxide, copper oxide or a mixture thereof.

[0172] In some embodiments, the sol is a silicon oxide (silica sol) or aluminum oxide (alumina or boehmite sol) based sol.

[0173] In some embodiments, the sol is a zirconium oxide or titanium oxide based sol.

[0174] In some embodiments, the sol is a multi-component oxide sol. For example, the sol may be comprised of binaries of oxides of zirconium and yttrium, zirconium and cerium, zirconium and calcium, barium and titanium, lithium and niobium, phosphorus and sodium, or boron and lithium. The sol may be a sol comprised of silicate, for example, binary silicates based on silica and boron oxide, aluminum oxide, germanium oxide, titanium oxide, zirconium oxide, strontium oxide, or iron oxide, ternary silicates, multi-component silicates having more than three constituents. In some embodiments, the sol is a multi-component oxide sol, for example, an aluminosilicate sol.

[0175] In particular, the sol can be obtained by a sol-gel process, i.e. by the hydrolysis of an organometallic precursor.

[0176] The organometallic precursor generally comprises at least one, in particular at least two, hydroxyl groups or hydrolyzable groups to form metal oxides upon their hydrolysis. Thus, the organometallic precursor is typically an organometallic alkoxide, an organometallic acetate, an organometallic carboxylate, an organometallic halide, an organometallic nitrate, an organometallic alkanoate or an organometallic acyloxide.

[0177] Examples of organometallic precursors include, but are not limited to, tetrachlorosilane, aluminum nitrate (which may be hydrolyzed in the presence of urea), tetramethoxysilane, tetraethoxysilane, diethyl(dimethoxy)silane, or triethyl(methoxy)silane.

[0178] The organometallic precursor is preferably an organometallic alkoxide.

[0179] The organometallic precursor is preferably a tetraethoxysilane or a tetramethoxysilane.

[0180] The hydrolysis of the organometallic precursor(s) is carried out in an aqueous medium. The aqueous medium may comprise exclusively water or may comprise a mixture of water and an organic solvent, for example methanol or ethanol, in order to make the mixture homogeneous. The amount of organic solvent is typically less than 12 times the volume of the organometallic precursor, preferably 4 times less than this volume, even more preferably 2 times less than this volume, and in particular less than 0.5 times this volume. In certain embodiments, the organometallic precursor is placed in water with stirring until a homogeneous mixture is formed by partial hydrolysis of the precursor.

[0181] Optionally, a material according to the invention is prepared from a functionalized silane, in order to modify its adsorption and retention properties for a chromatographic or reaction application.

[0182] Parmi les silanes fonctionnels utilisables on citera entre autres de façon non limitative les Dodecyltrimethoxysilane, Octadecyltrimethoxysilane, Hexadecyltrimethoxysilane, Methyltrimethoxysilane, n-Octyltriethoxysilane, n-Octyltrimethoxysilane, n- Propyltrimethoxysilane, n-Propyltriethoxysilane, Methyltriacetoxysilane, Ethyltriacetoxysilane, Vinyltriacetoxysilane, Vinyltri(2-methoxyethoxy)silane, 3- Chloropropyltriethoxsilane, 3-Chloropropyltrimethoxysilane, 3- Chloropropylmethyldimethoxysilane, 3-Aminopropyltriethoxysilane, 2-Aminoethyl-3- aminopropyltrimethoxysilane, 3-Aminopropyltrimethoxysilane, Bis(trimethoxysilypropyl)amine, 3-Ureidopropyltrimethoxysilane, 3- Glycidoxypropyltrimethoxysilane, 3-Glycidoxypropylmethyldimethoxysilane, 3- Methacryloxypropyltrimethoxysilane, : 3-Methacryloxypropylmethyldimethoxysilane, Bis(3- triethoxysilylpropyl)tetrasulfide, Bis(3-triethoxysilylpropyl)disulfide, 3- Mercaptopropyltrimethoxysilane, 3-Mercaptopropylmethyldimethoxysilane,Vinyltris(methylethylketoxime)silane, vinyl Oximino Silane, Methyltris(methylethylketoxime)silane, Methyl Oximino Silane, Tetra(methylethylketoxime)silane, Trifluoropropylmethyldimethoxylsilane, silanes containing epoxy bonds, etc. Advantageously, the sol-gel process can be carried out by hydrolysis of an organometallic compound MOM (M denotes the metal of the organometallic precursor).,

[0183] In the case where M is a silicon atom, in particular and in a non-limiting manner, the MOR, MNR, MSR, MOB bonds, where R is an organic group, of the organometallic precursor are considered to be hydrolyzable.

[0184] In the case where M is a silicon atom, in particular and without limitation, the bonds, MC-, are generally considered non-hydrolyzable. It should be noted, however, that the addition of substituents or heteroatoms such as O, N, S, etc. on the carbon C can make these MC bonds fragile. In the latter case the bonds are considered hydrolyzable.

[0185] Thus, for example, for one mole of tetraalkoxysilane of formula M(OR)4 with M = Si, OR being the alkoxy radical, R being for example a methyl or ethyl group, the stoichiometric quantity of water required is two moles / mole of tetraalkoxysilane.

[0186] Si(OR)4+ 2 H2O -> SiO2+ 4 ROH

[0187] Thus, for example, for one mole of trialkoxysilane of formula R'M (OR)3 with M = Si, OR being the alkoxy radical, R being an alkyl, for example a methyl or ethyl group, R' being an alkyl, for example a methyl or ethyl group, the stoichiometric quantity of water required is 1.5 moles / mole of trialkoxysilane.

[0188] Thus, for example, for one mole of dialkoxysilane of formula R'R”M (OR)2 with M = Si, OR being the alkoxy radical, R being an alkyl, for example a methyl or ethyl group, R' being an alkyl, for example a methyl or ethyl group, R” being an alkyl, for example a methyl or ethyl group, the stoichiometric quantity of water required is one mole / mole of dialkoxysilane

[0189] In all these estimates, we take into account the fact that the silanols resulting from hydrolysis and present on silicon couple two by two to form siloxane bridges in order to form silica gel, a reaction which itself restores a water molecule to the reaction medium per siloxane bridge created.

[0190] R' and R” can advantageously also consist of radicals Dodecyl, Octadecyl, n-Octyl, n-Propyl, n-Butyl, Vinyl, 3-Chloropropyl, 3-Aminopropyl, 2-Aminoethyl- 3-aminopropyl, 3-Aminopropyl, 3-Ureidopropyl, 3-Glycidoxypropyl, 3-Glycidoxypropyl, 3-Methacryloxypropyl, Bis(propyl)tetrasulfide, Bis(propyl)disulfide, 3-Mercaptopropyl, Trifluoropropyl, contain epoxy bonds, etc.OR can advantageously be an alkoxy, methoxy, ethoxy, acyloxy, acetoxy, ketoxime, methylethylketoxime, Oximino, etc..., (OR)4, (OR) 3I(OR)2, which can themselves represent 4, 3, or 2 R groups listed above, all identical or different. The organometallic precursor hydrolysis step is typically catalyzed by an acid or a base. The choice of acid or base catalysis typically depends on the precursor(s) used.

[0191] Advantageously, in the case where the metallic part of the organometallic precursor is made up of one or more silicon atoms, a succession of catalysis can be carried out: for example, a first acid hydrolysis can be carried out preferably before adding the porous particles to the soil, followed by an addition of base resulting in hydrolysis in the basic medium of the soil. Acid catalysis produces more linear and less hydrolyzed organic silicon polymers than those produced by basic catalysis, because they contain a lot of residual alkoxy functions.

[0192] The sols useful in the context of the present invention comprise nanoparticles (colloidal particles) of size less than 300 nm as determined by means of a laser particle size analyzer. Typically, the sols useful in the context of the present invention comprise nanoparticles of size d1 , typically of diameter d1 , with d1 ranging from 2 to 150 nanometers, preferably from 2 to 70 nanometers, as determined by means of a laser particle size analyzer. It is understood that when the nanoparticles of the sol are not spherical, the dimension d1 refers to the largest dimension of the nanoparticles.

[0193] Advantageously, the sol comprises an initial volume proportion of nanoparticles ranging from 5% to 50%, more advantageously ranging from 10% to 30%.

[0194] Advantageously, the soil nanoparticles have a surface chemistry that allows the creation of hydrogen bonds or chemical bonds, for example ionic bonds, covalent bonds, acceptor-donor bonds, etc., or Van der Waals bonds, electrostatic bonds of the dipole-dipole type, the dipoles being able to be induced or permanent, between the nanoparticles. These bonds allow strong cohesion of the nanoparticles between them in the dry state.

[0195] Step (b): supply of porous solid particles

[0196] The porous solid particles useful in the context of the present invention typically have a diameter of less than 500 micrometers, advantageously less than 100 micrometers, even more advantageously less than 25 micrometers or even less than 3 micrometers as measured by a laser granulometer (e.g. Fritsch wet dispersion analyzer). The porous solid particles useful in the context of the present invention may be porous solid particles having a diameter greater than 5 nanometers, advantageously greater than 100 nanometers as measured by a laser granulometer.

[0197] Porous solid particles have pores whose size, typically the diameter, is such that soil nanoparticles do not penetrate them. Thus, the pores of porous solid particles may have a diameter d2 with d2<10*d1. Advantageously, the porous solid particles have a pore population with diameters less than 10 times, more advantageously three times, and even more preferably one time the diameter of the soil nanoparticles. Typically, the porous solid particles have pores whose diameter varies from 2 to 150 nm or from 4 to 70 nm as measured by the BET porosimetry method by nitrogen adsorption.

[0198] Porous solid particles are wettable by the liquid medium of the soil, that is, they have the capacity to absorb the liquid medium into their pores.

[0199] The porous solid particles may be particles of silica gel, activated alumina, silico aluminate, any of the substances constituting the sol, porous metal, glass, zeolites, carbon black, activated carbon, pumice stone, kieselgur, catalysts, particles subsequently consumable by a chemical reaction, etc. or porous polymers. In the case where the porous solid particles are particles of porous polymers, they may be polystyrene copolymers, divinyl benzene copolymers, acrylic polymers, porous fluorinated polymers, porous polyolefins or proteins.

[0200] Advantageously, the porous solid particles have a high specific surface area, typically ranging from 20 m 2 per gram at 2000 m 2 per gram, more advantageously ranging from 70 m 2 per gram at 700 m 2 per gram.

[0201] Advantageously, the porous solid particles have a pore volume ranging from 10% to 90% by volume, more advantageously ranging from 20% to 60% by volume.

[0202] The porous solid particles represent from 20% to 80% by volume of the final material, advantageously more than 30% by volume, and even more advantageously more than 40% by volume of the final material.

[0203] Step (c): addition of porous solid particles to the soil so as to achieve a volume fraction of nanoparticles in the liquid greater than 20%

[0204] The addition of the porous solid particles to the soil so as to achieve a volume fraction of nanoparticles greater than 20% in the liquid makes it possible to achieve conditions that allow the drying of the material to be carried out under the conditions corresponding to the final part of drying or second phase as previously mentioned. Preferably, the addition of the porous solid particles to the soil makes it possible to achieve a volume fraction of nanoparticles in the liquid greater than 30% or even greater than 40%.

[0205] In the particular case of silica gel particles bound by a colloid or silica sol, gel particles with a specific density of between 0.3 and 0.8 kg / l are preferably used.

[0206] Gel particles with a pore volume of 0.5 to 1.5 cm are preferably used. 3 / g,

[0207] Gel particles having a proportion of mesopores between 2 and 50 nm greater than 50% by volume and preferably greater than 80% are preferably used.

[0208] Gel particles having a proportion of mesopores and small macropores less than 70 nm greater than 50% by volume and preferably greater than 80% can also be used.

[0209] Gel particles having a proportion of mesopores and small macropores less than 150 nm greater than 50% by volume and preferably greater than 80% can also be used.

[0210] The silica sol used may have a particle size preferably between 4 nm and 100 nm. Its concentration will preferably be greater than 100 g per liter, preferably greater than 300 g / l.

[0211] Advantageously, the mass of colloidal silica used per volume of soil will be greater than 150 g / litre, more preferably greater than 300 g / L, even more advantageously greater than 500 g / L.

[0212] Advantageously, silica gel is added to the sol until a high viscosity is obtained. Advantageously this viscosity is greater than 0.1 Pa.s, more advantageously greater than 1 Pa.s.

[0213] Advantageously, the soil is completely deionized before use by passing it through an ion exchanger.

[0214] Advantageously in the case of a silica gel, the final mixture has a pH of less than 5, preferably less than 3, even more preferably less than 2.

[0215] According to another embodiment, the final mixture has a pH greater than 9.

[0216] Step (d): drying

[0217] Drying is carried out in a conventional manner.

[0218] An advantage of the process is the great simplification of the drying step of monolithic macroscopic mesoporous materials.

[0219] Typically, drying is carried out by heating to a temperature ranging from 20 to 120°C, preferably from 60 to 100°C. Heating can be carried out very simply by passing through an oven at a temperature lower than, equal to or higher than the evaporation temperature of the liquid solvent. The oven can be conventional, or vacuum in the case of non-aqueous solvents. Drying can also be carried out in an atmosphere comprising a partial pressure of one or more of the components of the liquid phase at a controlled rate. This last gentle and controlled drying method can in particular be used on aqueous solvents. Advantageously, it can be used in an identical manner to the operating methods used to dry materials resulting from sol-gel synthesis.

[0220] Optional steps

[0221] The process of the present invention may comprise before the drying step d) or after it one or more optional steps.

[0222] Admixtures can be added to the soil to give the prepared material greater mechanical strength.

[0223] Advantageously, this adjuvant can be a plaster.

[0224] Advantageously, this adjuvant can be made of fibers, fibrils, microfibers or nanofibers. These fibers can be made of mineral or organic fibers, fiberglass, quartz, cellulose, organic polymers. Advantageously, these microfibers can be made of glass microfibers or organic polymer microfibers. Advantageously, filiform single crystals known as whiskers can be used, such as silica whiskers or potassium titanate whiskers.

[0225] For example, the process may include a step of adding fiberglass or potassium titanate whiskers.

[0226] For example, the method may include a step of adding ground fiberglass or microfiberglass.

[0227] For example, the process may include a step of adding potassium titanate whiskers onto which a layer of amorphous silica has been precipitated beforehand.

[0228] Adjuvants can be added to the soil to provide the material with functionalization. Such adjuvants can be a catalyst, an adsorbent such as activated carbon or zeolites or an ion exchanger, etc.

[0229] In particular, such an adjuvant can be a peptized or non-peptized clay.

[0230] The method of the present invention may comprise a step of surface treatment of one or more components entering into the composition of the material or the prepared material in order to give it a desirable property. For example, silanes such as aminopropylsilane, octylsilane, octadecylsilane aminopropylsilane, may be used or coupling agents or a layer of organic, polymeric or mineral material may be precipitated by any suitable technique on the external surface of the material obtained or on one of its components.

[0231] Advantageously, mechanical strengthening of the material can be achieved by precipitation of a mineral oxide such as silica or by the phenomenon known as Ostwald ripening.

[0232] Advantageously, reinforcement can be achieved by high-temperature sintering.

[0233] Advantageously, the method according to the invention has at least one of the following additional steps between step (c) and step (d):

[0234] (c) adding a binding agent initiating the formation of a gel from the sol; and

[0235] (c”) freezing of the soil by an increase in temperature, typically from room temperature to 90°C or even 120°C or by the addition of an agent causing coagulation of the soil such as a surfactant polymer, a surfactant, an ion charged with more than one elementary charge, etc.

[0236] The binding agent will advantageously have a delayed action allowing the mixture to be handled in the liquid state before it freezes. In the case of silica sols, this binding agent will advantageously be a divalent or trivalent cation, such as calcium or aluminum.

[0237] It could also be a diamine or a polyamine or one of their salts.

[0238] Adding a binding agent can be avoided when a high-purity final material is desired. Alternatively, the binding agent can be removed at a later stage of the process, such as by vaporization, dissolution and washing with a solvent, or pyrolysis.

[0239] The method can be implemented to prepare materials consisting of amorphous silica. According to this embodiment, powdered silica gels are mixed with silica sols so as to produce a material consisting of amorphous silica.

[0240] The method can be used to prepare materials consisting of amorphous alumina. In this embodiment, powdered activated aluminas are mixed with boehmite sols or nanoparticles or sols consisting of activated alumina.

[0241] Special embodiments

[0242] In particular embodiments of the invention, the method comprises the following steps: (a) providing a sol consisting of nanoparticles of size d1 dispersed in a liquid;

[0243] (b) providing solid particles wettable by said liquid;

[0244] (c) addition of solid particles to the soil so as to achieve a volume fraction of nanoparticles of size d1 in the liquid greater than 5%; then

[0245] (d) drying.

[0246] In particular embodiments of the invention, the method comprises the following steps:

[0247] (a) providing a sol consisting of nanoparticles of size d1 dispersed in a liquid;

[0248] (b) providing porous solid particles whose pores have a diameter d2 with d2 < 10*d1, said porous solid particles being wettable by said liquid;

[0249] (c) addition of the porous solid particles to the soil so as to achieve a volume fraction of nanoparticles of size d1 in the liquid greater than 20%; then

[0250] (d) drying.

[0251] In particular embodiments of the invention, the method comprises the following steps:

[0252] (a) providing a sol consisting of particles of size d1 , in particular nanoparticles of size d1 , dispersed in a liquid;

[0253] (b) providing solid particles, said porous solid particles being dry and wettable by said liquid or in a suspended state in a liquid miscible with that dispersing the sol;

[0254] (c) addition of solid particles or their dispersion to the soil;

[0255] (d) removal of excess liquid by evaporation, liquid-liquid extraction or by membrane filtration so as to achieve a volume fraction of particles of size d1 in the liquid greater than 20%; then

[0256] (e) drying.

[0257] In particular embodiments of the invention, the method comprises the following steps:

[0258] (a) providing a sol consisting of particles of size d1 , in particular nanoparticles of size d1 , dispersed in a liquid;

[0259] (b) providing porous solid particles whose pores have a diameter d2 with d2 < d1, said porous solid particles being dry and wettable by said liquid or in a suspended state in a liquid miscible with that dispersing the sol;

[0260] (c) addition of the porous solid particles or their dispersion to the soil; (d) removal of the excess liquid by evaporation, liquid-liquid extraction or by membrane filtration so as to achieve a volume fraction of particles of size d1 in the liquid greater than 20%; then

[0261] (e) drying.

[0262] In particular embodiments of the invention, the method comprises the following steps:

[0263] (a) providing nanoparticles of size d1, in particular nanoparticles of size d1, in the dry state;

[0264] (b) providing solid particles immersed in a liquid;

[0265] (c) addition of the nanoparticles to the suspended porous solid particles so as to achieve a volume fraction of nanoparticles in the liquid greater than 20%; then

[0266] (d) drying

[0267] In particular embodiments of the invention, the method comprises the following steps:

[0268] (a) providing nanoparticles of size d1, in particular nanoparticles of size d1, in the dry state;

[0269] (b) providing porous solid particles having pores of diameter d2 with d2 < d1, said porous solid particles being immersed in a liquid;

[0270] (c) addition of the nanoparticles to the suspended porous solid particles so as to achieve a volume fraction of nanoparticles in the liquid greater than 20%; then

[0271] (d) drying

[0272] In particular embodiments of the invention, the method comprises the following steps:

[0273] (a) providing a soil consisting of particles of size d1, in particular nanoparticles of size d1, in the dry state;

[0274] (b) providing solid particles immersed in a liquid;

[0275] (c) addition of porous solid particles to the soil;

[0276] (d) removal of excess solvent by evaporation, liquid-liquid extraction or by membrane filtration so as to achieve a volume fraction of particles of size d1 in the liquid greater than 20%; then

[0277] (e) drying. In particular embodiments of the invention, the method comprises the following steps:

[0278] (a) providing a soil consisting of particles of size d1, in particular nanoparticles of size d1, in the dry state;

[0279] (b) providing porous solid particles having pores of diameter d2 with d2 < d1, said porous solid particles being immersed in a liquid;

[0280] (c) addition of porous solid particles to the soil;

[0281] (d) removal of excess solvent by evaporation, liquid-liquid extraction or by membrane filtration so as to achieve a volume fraction of particles of size d1 in the liquid greater than 20%; then

[0282] (e) drying.

[0283] In particular embodiments of the invention, the method comprises the following steps:

[0284] (a) providing a sol consisting of particles of size d1, in particular nanoparticles of size d1, concentrated at more than 40%, and preferably at more than 45% by volume of solid particles;

[0285] (b) supply of solid particles

[0286] (d) adding said solid particles to the soil;

[0287] (e) drying.

[0288] In particular embodiments of the invention, the method comprises the following steps:

[0289] (a) providing a sol consisting of particles of size d1, in particular nanoparticles of size d1, concentrated at more than 20%, and preferably at more than 45% by volume of solid particles;

[0290] (b) providing porous solid particles whose pores have a diameter d2 with d2 < d1;

[0291] (c) filling the porosity of the particles with a third liquid body solidified after addition, such as a paraffin, a wax or a liquid precursor polymerized in situ

[0292] (d) adding said filled porous solid particles to the soil;

[0293] (e) drying.

[0294] (f) elimination of the solid third body by fusion, vaporization, chemical attack or pyrolysis and oxidation.

[0295] In each of these particular embodiments, the method may comprise at least one of the following additional steps between step (c) and step (d):

[0296] (c') addition of a binding agent initiating the formation of a gel from the sol; and (c”) freezing of the sol by raising the temperature, typically from room temperature to 90°C or even 120°C or by addition of an agent causing coagulation of the sol such as a surface-active polymer, a surfactant, an ion charged with more than one elementary charge, etc.

[0297] This produces a monolithic disc 200 mm in diameter and 20 mm thick, exhibiting a relative linear shrinkage of less than 0.1% when dried, obtained using an aqueous process.

[0298] Process for preparing porous material (organic solvent option)

[0299] The material according to the invention can be manufactured by a process comprising the following steps:

[0300] (a) providing a sol consisting of a first population of solid particles of a first size (d1), in particular nanoparticles of said first size (d1), dispersed in an aqueous solvent;

[0301] (a') transferring said sol into a second organic solvent miscible with the first solvent;

[0302] (b) providing a second population of solid particles having pores of a second size (d2) less than 10 times the first size (d1); thus, the particles of the first population do not penetrate into the pores of the particles of the second population;

[0303] (c) adding said second population of solid particles to the soil;

[0304] (d) drying.

[0305] Step a: provision of a soil consisting of solid particles of a first size

[0306] The soil can be based on any compound that provides cohesion to the material. The soil comprises a first population of solid particles of size d1.

[0307] This first population advantageously comprises nanoparticles of size d1, less than 300 nm as determined using a laser granulometer. Typically, the soil comprises nanoparticles of size d1 between 2 and 150 nm, preferably between 2 and 70 nm.

[0308] When nanoparticles are spherical, the size d1 corresponds to the diameter of these nanoparticles. Otherwise, the size d1 refers to the largest dimension of the nanoparticles.

[0309] Advantageously, the sol comprises an initial volume proportion of nanoparticles ranging from 5% to 50%, more advantageously ranging from 10% to 30%. In particular, the sol of said first population of solid particles is concentrated at more than 40%, and preferably 45%, by volume of solid particles. Advantageously, the nanoparticles of the sol have a surface chemistry allowing the creation of hydrogen bonds or chemical bonds, for example ionic bonds, covalent bonds, acceptor-donor bonds, or Van der Waals bonds, electrostatic bonds of the dipole-dipole type, the dipoles being able to be induced or permanent, between the nanoparticles. These bonds allow strong cohesion of the nanoparticles between them in the dry state.

[0310] Said population of nanoparticles may comprise organic nanoparticles and / or organometallic nanoparticles.

[0311] The sol may be, but is not limited to, a silica sol, a boehmite sol, a macromolecular suspension, for example a colloidal suspension of a polymer such as pectin (polysaccharide), a suspension of proteins such as ovalbumin or gelatin, a suspension of high molecular weight carbohydrates such as starch or cellulose, a suspension of colloidal metals such as silver (collargol), gold or copper, a micellar suspension for example based on surface-active compounds (detergents), a colloidal suspension of an elastomer such as latex, or a suspension of carbon particles such as carbon nanotubes.

[0312] The sol may more particularly be a sol based on aluminum oxide (alumina sol), silicon oxide (silica sol), zirconium oxide, titanium oxide, rare earth oxide such as yttrium, cerium or lanthanum, boron oxide, iron oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, germanium oxide, phosphorus oxide, lithium oxide, potassium oxide, sodium oxide, niobium oxide, copper oxide or a mixture thereof.

[0313] The soil may be a multi-component oxide soil. For example, the soil may consist of binary oxides of zirconium and yttrium, zirconium and cerium, zirconium and calcium, barium and titanium, lithium and niobium, phosphorus and sodium, or boron and lithium. The soil may be a silicate soil, for example, binary silicates based on silica and boron oxide, aluminum oxide (aluminosilicate), germanium oxide, titanium oxide, zirconium oxide, strontium oxide, or iron oxide, ternary silicates, or multi-component silicates with more than three constituents.

[0314] In particular, the sol can be obtained by a sol-gel process, i.e. by the hydrolysis of an organometallic precursor.

[0315] The organometallic precursor generally comprises at least one, in particular at least two, hydroxyl groups or hydrolyzable groups to form metal oxides upon their hydrolysis. Thus, the organometallic precursor is typically an organometallic alkoxide, an organometallic acetate, an organometallic carboxylate, an organometallic halide, an organometallic nitrate, an organometallic alkanoate or an organometallic acyloxide.

[0316] Examples of organometallic precursors include, but are not limited to, tetrachlorosilane, aluminum nitrate (which may be hydrolyzed in the presence of urea), tetramethoxysilane, tetraethoxysilane, diethyl(dimethoxy)silane, or triethyl(methoxy)silane.

[0317] The organometallic precursor is preferably an organometallic alkoxide, or even more preferably a tetraethoxysilane or a tetramethoxysilane.

[0318] The hydrolysis of the organometallic precursor(s) is carried out in an aqueous medium. The aqueous medium may comprise exclusively water or may comprise a mixture of water and an organic solvent, for example methanol or ethanol, in order to make the mixture homogeneous. The amount of organic solvent is typically less than 12 times the volume of the organometallic precursor, preferably 4 times less than this volume, even more preferably 2 times less than this volume, and in particular less than 0.5 times this volume. In certain embodiments, the organometallic precursor is placed in water with stirring until a homogeneous mixture is formed by partial hydrolysis of the precursor.

[0319] Optionally, a material according to the invention is prepared from a functionalized silane, in order to modify its adsorption and retention properties for a chromatographic or reaction application.

[0320] Parmi les silanes fonctionnels utilisables, on citera entre autres, de façon non limitative, les Dodecyltrimethoxysilane, Octadecyltrimethoxysilane, Hexadecyltrimethoxysilane, Methyltrimethoxysilane, n-Octyltriethoxysilane, n-Octyltrimethoxysilane, n- Propyltrimethoxysilane, n-Propyltriethoxysilane, Methyltriacetoxysilane, Ethyltriacetoxysilane, Vinyltriacetoxysilane, Vinyltri(2-methoxyethoxy)silane, 3- Chloropropyltriethoxsilane, 3-Chloropropyltrimethoxysilane, 3- Chloropropylmethyldimethoxysilane, 3-Aminopropyltriethoxysilane, 2-Aminoethyl-3- aminopropyltrimethoxysilane, 3-Aminopropyltrimethoxysilane, Bis(trimethoxysilypropyl)amine, 3-Ureidopropyltrimethoxysilane, 3- Glycidoxypropyltrimethoxysilane, 3-Glycidoxypropylmethyldimethoxysilane, 3- Methacryloxypropyltrimethoxysilane, 3-Methacryloxypropylmethyldimethoxysilane, Bis(3- triethoxysilylpropyl)tetrasulfide, Bis(3-triethoxysilylpropyl)disulfide, 3- Mercaptopropyltrimethoxysilane, 3-Mercaptopropylmethyldimethoxysilane,Vinyltris(methylethylketoxime)silane, vinyl Oximino Silane, Methyltris(methylethylketoxime)silane, Methyl Oximino Silane,

[0321] Tetra(methylethylketoxime)silane, Trifluoropropylmethyldimethoxylsilane, silanes containing epoxy bonds, etc.

[0322] The sol-gel process can be carried out by hydrolysis of an organometallic compound MOM (M denotes the metal of the organometallic precursor).

[0323] In the case where M is a silicon atom, in particular and in a non-limiting manner, the MOR, MNR, MSR, MOB bonds, where R is an organic group, of the organometallic precursor are considered to be hydrolyzable. In the case where M is a silicon atom, in particular and in a non-limiting manner, the MC- bonds are generally considered to be non-hydrolyzable. It should be noted, however, that the addition of substituents or heteroatoms such as O, N, S, etc. on the C carbon can make these MC bonds fragile. In the latter case, the bonds are considered to be hydrolyzable.

[0324] Thus, for example, for one mole of tetraalkoxysilane of formula M(OR)4 with M = Si, OR being the alkoxy radical, R being for example a methyl or ethyl group, the stoichiometric quantity of water required is two moles / mole of tetraalkoxysilane.

[0325] Si(OR)4+ 2 H2O -> SiO2+ 4 ROH

[0326] Thus, for example, for one mole of trialkoxysilane of formula R'M(OR)3 with M = Si, OR being the alkoxy radical, R being an alkyl, for example a methyl or ethyl group, R' being an alkyl, for example a methyl or ethyl group, the stoichiometric quantity of water required is 1.5 moles / mole of trialkoxysilane.

[0327] Thus, for example, for one mole of dialkoxysilane of formula R'R”M(OR)2 with M = Si, OR being the alkoxy radical, R being an alkyl, for example a methyl or ethyl group, R' being an alkyl, for example a methyl or ethyl group, R” being an alkyl, for example a methyl or ethyl group, the stoichiometric quantity of water required is 1 mole / mole of dialkoxysilane.

[0328] In all these estimates, we take into account the fact that the silanols resulting from hydrolysis and present on silicon couple two by two to form siloxane bridges in order to form silica gel, a reaction which itself restores a water molecule to the reaction medium per siloxane bridge created.

[0329] R' and R” can advantageously also consist of radicals Dodecyl, Octadecyl, n-Octyl, n-Propyl, n-Butyl, Vinyl, 3-Chloropropyl, 3-Aminopropyl, 2-Aminoethyl- 3-aminopropyl, 3-Aminopropyl, 3-Ureidopropyl, 3-Glycidoxypropyl, 3-Glycidoxypropyl, 3-Methacryloxypropyl, Bis(propyl)tetrasulfide, Bis(propyl)disulfide, 3-Mercaptopropyl, Trifluoropropyl, contain epoxy bonds, etc. OR can advantageously be an alkoxy, methoxy, ethoxy, acyloxy, acetoxy, ketoxime, methylethylketoxime, Oximino, etc... radical, (OR)4, (OR) 3I(OR)2, which can themselves represent 4, 3, or 2 R groups listed above, all identical or different. The organometallic precursor hydrolysis step is typically catalyzed by an acid or a base. The choice of acid or base catalysis typically depends on the precursor(s) used.

[0330] In the case where the metallic part of the organometallic precursor is advantageously made up of one or more silicon atoms, a succession of catalysis can be carried out: for example, a first acid hydrolysis can be carried out preferably before adding the porous particles to the soil, followed by an addition of base resulting in hydrolysis in the basic medium of the soil. Acid catalysis produces more linear and less hydrolyzed organic silicon polymers than those produced by basic catalysis, because they contain a lot of residual alkoxy functions.

[0331] Step a': transfer of the soil into an organic solvent

[0332] The sol may be transferred into an organic liquid, the second solvent preferably being miscible with the first aqueous solvent, by volatilizing the mixture so as to increase its proportion of organic solvent. The second organic solvent is preferably selected from miscible organic solvents having a boiling point higher than that of water.

[0333] The organic solvent may be an alcohol, a polyol, a polyether such as polyethylene glycol or propylene glycol, or an amino solvent, etc.

[0334] Among the solvents which can be used, we will note in particular methanol, ethanol, the different isomers of propanol and in particular isopropanol, the different isomers of butanol and in particular tert-butanol, the different isomers of pentanol, ethylene glycol, propylene glycol, glycerol, light or heavy amines having from 1 to 12 carbon atoms, primary, secondary or tertiary, amides, carboxylic acids such as acetic acid, propionic acid, butyric acid, formic acid, benzoic acid, amino acids, aldehydes such as ethanal, formalin, propanal, ketones such as acetone, propanone, methyl ethyl ketone, methyl tert-butyl ketone, methyl isobutyl ketone, derivatives substituted by these groups of aromatic molecules, heterocycles and their substituted derivatives, ethers such as diethyl ether, diisopropyl ether, methyltert-butyl ether, tetrahydrofuran, polyethylene glycol,polypropylene glycol, branched or unbranched alkanes, unsaturated molecules, aromatic hydrocarbons, halogenated, fluorinated, chlorinated, brominated, iodinated derivatives, silicone solvents, solvents such as dimethyl formamide, dimethyl sulfoxide, polyfunctional molecules, etc.,

[0335] Among the solvents that can be used, particular mention will be made of methanol, ethanol, the various isomers of propanol and in particular isopropanol, the various isomers of butanol and in particular tert-butanol, ethylene glycol, propylene glycol, glycerol. The organic solvent may comprise a polymerizable or crosslinkable body, in particular a monomer, an oligomer or a subsequently polymerized macromolecule. It may be an acrylate or a methacrylate, preferably hydroxyethyl acrylate or methacrylate, glyceryl monoacrylate or monomethacrylate, glycidyl acrylate or methacrylate, methyl methacrylate, 2-(Dimethylamino)ethyl methacrylate, 2-(Diethylamino)ethyl methacrylate, 2-(Diisopropylamino)ethyl methacrylate, 2-(tert-Butylamino)ethyl methacrylate, hydroxypropylamine methacrylate, hydroxypropyl dimethylamine methacrylate, N-[3-dimethylamino)propyl]methacrylamide, etc.

[0336] Preferably, the polymerizable or crosslinkable body included in the organic solvent consists of a hydroxyethyl acrylate or methacrylate, glyceryl monoacrylate or monomethacrylate, glycidyl acrylate or methacrylate, methyl methacrylate.

[0337] Transferring the sol into an organic solvent has several advantages. Indeed, manufacturing the porous material according to the invention from a sol in organic phase makes it possible to obtain greater steric stabilization. It is also simpler to manufacture the material with particles (from the first population) of smaller size, in particular smaller than 11 nm. It is also possible to obtain a greater concentration (50% by mass) of the sols with a high specific surface area (500 m 2 / g) with high stability (insoluble).

[0338] Step b: providing a second population of solid particles having pores of a second size

[0339] The second population comprises at least one population of porous solid particles. In some embodiments, the second population comprises several different types of porous solid particles, each of which may have different particle sizes.

[0340] The porous solid particles useful in the context of the present invention typically have a size of less than 500 pm, advantageously less than 100 pm, even more advantageously less than 25 pm or even less than 3 pm as measured by a laser granulometer (e.g. Fritsch wet dispersion analyzer). The porous solid particles useful in the context of the present invention may be porous solid particles having a size greater than 5 nm, advantageously greater than 100 nm as measured by a laser granulometer.

[0341] When said particles are spherical, the size corresponds to the diameter of these particles. Otherwise, the size refers to the largest dimension of the particles. The porous solid particles have pores whose size, typically the diameter, is such that the soil nanoparticles do not penetrate therein. Thus, the second population of porous solid particles has pores of a second size d2 smaller than the first size d1. Advantageously, the pores have a diameter d2 less than 10 times, more advantageously less than 3 times, and even more preferably less than 2 times the size d1 of the soil nanoparticles. Typically, the particles of the second population have pores whose diameter varies from 2 to 150 nm or from 4 to 70 nm.

[0342] The porous solid particles of the second population have a pore volume ranging from 10% to 90% by volume, more advantageously ranging from 20% to 60% by volume.

[0343] Porous solid particles are wettable by the liquid medium of the soil, that is, they have the capacity to absorb the liquid medium into their pores.

[0344] Advantageously, the porous solid particles have a high specific surface area, typically ranging from 20 m 2 per gram at 2000 m 2 per gram, more advantageously ranging from 70 m 2 per gram at 700 m 2 per gram.

[0345] The second population of particles may consist of particles of a ceramic such as in particular silica, alumina, zirconium oxide, titanium oxide, an aluminosilicate. In this case, it may be particles of a silica gel, activated alumina, silico aluminate, any of the substances constituting the sol. Said second population may also consist of particles of an organic or mineral binder such as cellulose, plaster, metal silicates, a ferrous metal such as iron or its alloys, steel, a non-ferrous metal or at least one of their alloys, one or a plurality of polymers.In the case where the porous solid particles are polymer particles, they may be polyamides, polyimides, acrylic polymers, polyesters, polyurethanes, halogenated polymers, natural polymers, elastomers, polystyrene copolymers, divinyl benzene copolymers, porous fluorinated polymers, porous polyolefins or even proteins. The porous solid particles of the second population may also be glass particles, zeolites, carbon black, activated carbon, pumice stone, kieselgur, catalysts, or particles that can be subsequently consumed by a chemical reaction.

[0346] Advantageously, the second population of particles consists of particles of silica gel, activated alumina, silico aluminate, porous metal, glass, zeolites, carbon black, activated carbon, pumice stone, kieselgur, catalysts or porous organic or organometallic polymers.

[0347] According to a preferred embodiment, said second population of particles consists of a solid polymer. In this case, the second population can be considered as composed of a single crosslinked molecule or of an assembly of distinct individual polymeric elements constituted by the distinct polymeric chains. Said polymeric population extends as a continuum between the first population of nanometric particles.

[0348] The second population of particles may be physically or chemically reactive. According to one embodiment, it may comprise or consist of a mineral filler, serving as an agent of a separation technique such as a stationary phase for chromatography, as a catalyst, or as a filler consumable by a chemical reaction. According to another embodiment, it may comprise or consist of an organic or biological filler serving as an agent of a chemical or biological reaction. Said filler may then be an ion exchanger, a protein, a fragment of DNA or RNA or an immobilized enzyme.

[0349] Step c: addition of the second population of solid particles to the soil

[0350] The addition of the porous solid particles of the second population to the soil allows conditions to be placed that allow the drying of the material without fracturing. Indeed, the particular volume proportions of the two populations allow a critical density point to be reached in such a way that drying takes place on the flat and horizontal part of the drying curve shown in Figure 14. Thus, the material does not show any shrinkage during the transition between the wet material and the dried material, avoiding fracturing problems.

[0351] Figure 14 represents the percentage of volume shrinkage (V / Vo on the ordinate) of a soil sample as a function of its percentage weight loss (W / Wo on the abscissa). It can be seen that shrinkage becomes negligible for soil G beyond a critical point located in this case for V / Vo = approximately 25%, and from V / Vo = 15% for soil H.

[0352] The process according to the invention makes it possible to dry the fluid mixture carried before its final molding beyond the critical point so as to fit the shape of the mold without dimensional variation. The invention therefore gives rise to new products obtained by the process described below.

[0353] The first population of particles is therefore concentrated, separating the second population of particles before the drying step. This can be done by any means, evaporation, extraction, membrane separation, etc. This can be done before bringing the first and second populations into contact or after this.

[0354] In the particular case of silica gel particles bound by a colloid or silica sol, gel particles with a specific density of between 0.3 and 0.8 kg / l are preferably used.

[0355] Preferably, the gel particles used have a pore volume ranging from 0.2 to 1.5 cm3 / g. More particularly, they have a proportion of mesopores between 2 and 50 nm greater than 50% by volume and preferably greater than 80%. It is also possible to use gel particles having a proportion of mesopores and small macropores less than 70 nm greater than 50% by volume and preferably greater than 80%. It is also possible to use gel particles having a proportion of mesopores and small macropores less than 150 nm greater than 50% by volume and preferably greater than 80%.

[0356] The silica sol used may have a particle size preferably between 4 nm and 100 nm. Its concentration will preferably be greater than 100 g / L, or more preferably greater than 300 g / L. The mass of colloidal silica used per volume of sol may be greater than 150 g / L, preferably greater than 300 g / L, or even more preferably greater than 500 g / L.

[0357] Advantageously, silica gel is added to the sol until a high viscosity is obtained. This viscosity can be greater than 0.1 Pa.s, preferably greater than 1 Pa.s.

[0358] Advantageously, the soil is completely deionized before use by passing it through an ion exchanger.

[0359] The final mixture may have a pH of less than 5, preferably less than 3, even more preferably less than 2. According to another embodiment, the final mixture has a pH of greater than 9.

[0360] Step d: drying

[0361] Drying is carried out conventionally. An advantage of the process is the great simplification of the drying stage of monolithic macroscopic mesoporous materials.

[0362] Typically, drying is carried out by heating to a temperature between 20 and 120°C, preferably between 60 and 100°C.

[0363] Heating can be achieved very simply by passing it through an oven at a temperature higher than, equal to or lower than, the evaporation temperature of the liquid solvent. The oven can be conventional or vacuum.

[0364] Drying can also be carried out in an atmosphere comprising a partial pressure of one or more of the components of the liquid phase at a controlled rate. Advantageously, it can be used in a manner identical to the procedures used to dry materials from sol-gel synthesis.

[0365] Optional additional steps

[0366] The process of the present invention may comprise before the drying step d) or after it one or more optional steps.

[0367] Admixtures may be added to the soil to give the prepared material greater mechanical strength. Advantageously, this admixture may be a plaster. According to another embodiment, this admixture may consist of fibers, fibrils, microfibers or nanofibers. These fibers may consist of mineral or organic fibers, fiberglass, quartz, cellulose, organic polymers. Advantageously, these microfibers may consist of glass microfibers or microfibers of organic polymers. Advantageously, filiform single crystals known as whiskers may be used, such as silica whiskers or potassium titanate whiskers.

[0368] For example, the method may include a step of adding fiberglass or potassium titanate whiskers. The method may include a step of adding ground fiberglass or microfiberglass. The method may include a step of adding potassium titanate whiskers.

[0369] Adjuvants can be added to the soil to provide the material with functionalization. Such adjuvants can be a catalyst, an adsorbent such as activated carbon or zeolites or an ion exchanger, etc. In particular, such an adjuvant can be a peptized or non-peptized clay.

[0370] The method of the present invention may comprise a step of surface treatment of one or more components included in the composition of the material in order to give it a desirable property. For example, silanes such as aminopropylsilane, octylsilane, octadecylsilane, aminopropylsilane, or coupling agents may be used. A layer of organic, polymeric or mineral material may be precipitated by any suitable technique on the external surface of the material obtained or on one of its components.

[0371] Advantageously, mechanical strengthening of the material can be caused by precipitation of a mineral oxide such as silica or by the phenomenon known as Ostwald ripening.

[0372] Advantageously, reinforcement can be achieved by high-temperature sintering.

[0373] According to one embodiment, the method comprises, between steps (c) and (d), the steps of acting a binding agent initiating the formation of a gel from the sol and freezing the sol by raising the temperature. Typically, the temperature is raised from room temperature to 90°C, or even to 120°C. The freezing of the sol can alternatively take place by the action of an agent causing coagulation of the sol such as a surfactant polymer, a surfactant, an ion charged with more than one elementary charge, etc.

[0374] The binding agent will advantageously have a delayed action allowing the mixture to be handled in the liquid state before it freezes. The binding agent may be a salified or non-salified polyamine. In the case of silica sols, this binding agent may also be a diamine or a polyamine or one of their salts.

[0375] Adding a binding agent can be avoided when a high-purity final material is desired. Alternatively, the binding agent can be removed at a later stage of the process, such as by vaporization, dissolution and washing with a solvent, or pyrolysis.

[0376] The method can be implemented to prepare materials consisting of amorphous silica. According to this embodiment, powdered silica gels are mixed with silica sols so as to produce a material consisting of amorphous silica.

[0377] The method can be used to prepare materials consisting of amorphous alumina. In this embodiment, powdered activated aluminas are mixed with boehmite sols or nanoparticles or sols consisting of activated alumina.

[0378] Optionally, the method comprises an additional step of reinforcement by sintering or by adding a layer of a third solid material on and / or between the particles constituting it. Advantageously, this third solid material is a layer of amorphous silica obtained by a redissolution / redeposition phenomenon known as Ostwald ripening, or by precipitation of amorphous silica from a mineral precursor such as an acidified soluble silicate or a hydrolyzed alkoxysilane.

[0379] The method of manufacturing the material according to the invention may also comprise a step of injection and / or extrusion of one of its fluid precursors.

[0380] Optionally, the manufacturing process may include a step of machining said material or one of its solid precursors.

[0381] When the organic solvent comprises a polymerizable or crosslinkable body, the process may include a polymerization step. The polymerization may be carried out ionically in solution, thermally or photochemically using appropriate initiators. The polymerized body, transformed into threads, can then be used for 3D printing.

[0382] The polymerized body can be removed by dissolution, vaporization, chemical attack, hydrolysis, or pyrolysis and oxidation.

[0383] Figures 18 and 19 are microscope photos of micrometric channels and fluidic structures obtained with such an organic solvent (monomer) process.

[0384] Solid porous material

[0385] A solid porous material of the invention is characterized in that it comprises:

[0386] - a first population of particles made up of nanoparticles smaller than 300 nm;

[0387] - a second population of particles consisting of porous particles having a porosity ranging from 10% to 90% by volume, the second population of particles representing from 20% to 80% of the total volume of the material, wherein the first population of particles represents from 25% to 85% of the volume of the material present between the porous particles of the second population of particles.

[0388] The present invention also relates to the materials obtainable by the method of the present invention.

[0389] The first population of particles and the second population of particles are as described in connection with the method.

[0390] In particular, the first population of particles results from a sol as previously described. For example, the first population of particles may result from a sol based on (or comprise particles of) aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, rare earth oxide such as yttrium, cerium or lanthanum, boron oxide, iron oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, germanium oxide, phosphorus oxide, lithium oxide, potassium oxide, sodium oxide, niobium oxide, copper oxide or a mixture thereof. The second population of particles is more particularly particles of silica gel, activated alumina, silico aluminate, porous metal, glass, zeolites, carbon black, activated carbon, pumice stone, kieselgur, catalysts or porous polymers.

[0391] The material is advantageously characterized in that it comprises porous solid particles whose pores have a diameter d2 representing from 20% to 80%, or from 30% to 70% or from 30% to 50% by volume of the final material and nanoparticles of size d1 with 10*d1>d2 external to the porous solid particles whose volume fraction in the material external to the porous solid particles is greater than 25%, typically varying from 30 to 60% or greater than 40%, typically varying from 40 to 70%.

[0392] The material is advantageously characterized in that it comprises porous solid particles representing more than 25% by volume of the final material and nanoparticles external to the porous solid particles whose volume fraction in the material external to the porous solid particles is greater than 20%.

[0393] The material is advantageously characterized in that it comprises porous solid particles representing more than 40% by volume of the final material and nanoparticles external to the porous solid particles whose volume fraction in the material external to the porous solid particles is greater than 40%.

[0394] The material is advantageously characterized in that it comprises porous solid particles representing more than 60% by volume of the final material and nanoparticles external to the porous solid particles whose volume fraction in the material external to the porous solid particles is greater than 50%.

[0395] The porous material generally has an overall pore volume greater than 35%, advantageously greater than 45% in volume fraction when the material is a silica gel, and the pore size(s) is(are) less than 150 nm. The porous material generally has an overall pore volume greater than 15%, more advantageously greater than 20% in volume fraction when the material is an activated alumina or an aluminosilicate, and the pore size(s) is(are) less than 150 nm.

[0396] The material according to the invention may comprise a filler of fibers, microfibers or nanofibers.

[0397] The material according to the invention is advantageously characterized in that the porous solid particles consist of a silica gel, and in that the nanoparticles come from a silica sol.

[0398] The material according to the invention is advantageously characterized in that the porous solid particles are made of activated alumina, and in that the nanoparticles come from a boehmite sol.

[0399] The material according to the invention is advantageously characterized in that it has a proportion of mesopores greater than 80% by volume.

[0400] The material according to the invention is characterized in that it may not exhibit any shrinkage during the transition between the wet object and the dried object. Furthermore, it can be made of refractory ceramic materials having extremely low thermal expansion coefficients such as silica. In order to achieve this result, the manufacturing process advantageously includes a step of gelling the colloidal particles before drying.

[0401] The material of the present invention may contain other optional additives, such as polymers, active substances for any industrial sector (pharmaceuticals, phytochemistry, chemistry), such as pastes, solid substances or liquids. It can be used to produce controlled release devices. It can be loaded with gas bubbles to lighten it, or any type of filler.

[0402] The material of the invention can be granulated or shaped in any desired way, for example tablet, brick, construction material, precision mold for metallurgy, mold for polymer parts, high-precision single-use molds, optical parts, high-precision parts with a very low coefficient of expansion and temperature resistance up to 600°C. In general, the particular molding ability of the material according to the invention, cold and with high production rates, will make it useful whenever high dimensional stability (zero shrinkage during molding and drying) is required associated with its other qualities: parts with a low coefficient of expansion (amorphous silica), temperature resistance, monomodal mesoporosity, wide variety of possible base materials. It can also be impregnated on supports such as fabrics or porous or non-porous films. It can be used as mesoporous mineral membranes, filters, etc.The material according to the invention can undergo optional steps and various post-treatments, such as vitrification by high-temperature sintering, impregnation with active substances, shaping before drying and / or machining.

[0403] Three masses of particles are involved in the definition of the material of the invention, rrip.min is the minimum quantity of particles that it is necessary to add to a given mass m s of soil in order to sufficiently concentrate the colloid. m p,mtn = maximum particle that we can add to a given mass m s of soil.

[0404] Two limitations may arise in practice: m p,maxi is the mass of particles that can be added before the mixture hardens completely due to the concentration of colloidal particles. This volume concentration is given by epslim. It represents the volume fraction of the interstitial liquid volume on the ground. Epslim will advantageously be taken equal to 0.35, more advantageously 0.50. m p ,max2 is the mass of particles that can be added before the mixture completely hardens due to the complete absorption of the colloid liquid by the extraparticle volume and the pore volume of the particles. This volume concentration is given by eps. It represents the volume fraction of the empty mixture external to the packed particles, eps will advantageously be taken equal to 0.35, more advantageously 0.40 in a bed of monodisperse particles.

[0405] In the case of a bed of polydisperse particles, eps will be deduced from the particle density dp and the density of the packed bed T by the formula:

[0406] Let m p the mass of particles whose void volume fraction is p v and the proper density is d p .

[0407] Let m s the mass of soil with density d s and liquid volume fraction s v and the volume fraction of colloidal solid s c . Let V s the volume of soil. Fraclim represents the minimum volume fraction of colloid in the soil. Eps represents the extraparticulate volume fraction in a cluster of packed particles. Note that d p is the proper density of the particle not that of a bed of particles.

[0408] The material according to the invention can be characterized by analyzing an image of its structure in order to distinguish the two populations. Advantageously, this image is produced by optical microscopy or by phase contrast microscopy or by scanning electron microscopy. More advantageously, the image will be obtained by transmission microscopy in order to identify the colloidal particles acting as binders.

[0409] Particularly advantageously, the image will be obtained by immersing the material according to the invention in a liquid with an index possibly polymerized in situ, cutting a thin thickness of material (between one and a few μm and one or a few tens of micrometers for example) and observation under a phase contrast optical microscope to highlight differences in refractive index between the coagulated sol and the charge particles.

[0410] In order to distinguish the two populations of particles present in the material according to the invention, one or more of the following criteria will be used:

[0411] 1. State of aggregation of the particles between them in the part coming from the particles and that coming from the colloid between the particles.

[0412] 2. Solid density of the two zones.

[0413] 3. Pore sizes of the two areas.

[0414] 4. Differences in size, structure, composition and appearance of materials in the two areas

[0415] Once the two particle sizes have been identified, a section of the material, possibly crimped in a suitable polymer, will be made and the surfaces occupied by the particles and the surfaces occupied by the soil will be measured on a surface by image analysis.

[0416] Once the two particle sizes have been identified, and their volume ratio identified, a porosity analysis will be carried out using the BET method.

[0417] Furthermore, the material according to the invention can be characterized using the following techniques: differential adsorption, metallic impregnation, transmission electron microscopy, refractive index mapping, Hf / NaOH differential dissolution, Castaing probe. The cracking and reactivity of the material also make it possible to characterize it.

[0418] The materials according to the invention can be macroporous, mesoporous or microporous by varying the porosities of the porous solid particles, which can be preserved until the end of the process, and the size of the nanoparticles of the soil, as well as their concentration after addition of the solid porous particles to the soil. The materials obtained can be perfectly monomodal from the point of view of pore size, or multimodal.

[0419] Pore ​​sizes between 4 and 80 nanometers can be obtained advantageously.

[0420] The materials according to the invention may advantageously have specific surfaces of between 1000 and 20 m 2 / g, and more advantageously between 700 and 70 m 2 / g.

[0421] Following a preferred route for implementing the invention, mesoporous materials will be produced.

[0422] Advantageously, these materials will only have less than ten percent of their pore volume in the form of micropores, advantageously less than one percent.

[0423] The invention is also a solid porous material characterized in that it comprises:

[0424] - a first population of particles consisting of nanoparticles of size less than 300 nm having a first pore size;

[0425] - a second population of particles consisting of porous particles having a porosity ranging from 10% to 90% by volume, the second population of particles representing from 20% to 80% of the total volume of the material, and whose average pore size is smaller than that of the first population; in which the first population is part of a network enclosing the second population in a solid continuum, and in which the first population of particles represents from 25% to 85% of the volume of the material present between the porous particles of the second population of particles.

[0426] Advantageously, the first population of particles represents more than 45% of the volume of the material present between the porous particles of the second population of particles, advantageously more than 50%, even more advantageously more than 55%, and more preferably more than 60% of this volume, and the average size of the pores of the part of material resulting from the agglomeration of said first population, between the porous particles of the second population of particles, or coagulum, is preferably less than 150 nm, advantageously less than 50 nm, and more advantageously less than 15 nm.

[0427] Advantageously, the average pore size of the coagulum is greater than 2 times the average pore size of the second population of porous particles, more advantageously greater than 5 times this, and even more preferably greater than 10 times this. In a particularly preferred manner, the average pore size of the coagulum is greater than 5 times the average pore size of the second population of porous particles.

[0428] The invention also relates to a solid porous material characterized in that it comprises:

[0429] - a first population of particles made up of nanoparticles smaller than 300 nm;

[0430] - at least one other population of particles comprising one or more components distributed according to one or more particle sizes, the other population of particles representing from 20% to 80% of the total volume of the material, in which the other population of particles carries on its surface a reversible or irreversible fixing agent of at least one chemical species.

[0431] Advantageously, the agent for fixing a chemical species is an antigen characteristic of an antibody to be isolated. Advantageously, the agent for fixing a chemical species is a catalyst such as, for example, an enzyme.

[0432] Indeed, in techniques involving the contact of a fluid phase and a divided and porous solid to achieve an exchange of matter between these two phases, we seek to ensure the fastest possible penetration of the molecules brought by the fluid into the porous solid in order to obtain a desired goal, molecular separation or chemical reaction. In parallel, a high specific surface area for exchange or interaction is desired; it turns out that these two requirements are often contradictory. Indeed, a high exchange surface area requires small pores, in which the molecules diffuse more slowly. One solution would be to produce solid particles with a high specific surface area as small as possible, or even micron-sized, but obtaining and handling them is more difficult and they have the serious drawback of presenting a very high resistance to the passage of a fluid when used in a percolated bed.This pressure produces enormous additional costs making this solution unaffordable in most cases.

[0433] This is the case whether the fluid is in a liquid, supercritical or gaseous state.

[0434] A means of combining these two advantages consists, according to the present invention, in concentrating the small pores in porous particles as small as possible, with a high specific surface area and a small pore size, in order to limit the diffusional path of the molecules to said surface and therefore to accelerate as much as possible the phenomena of transfer of matter which occur there, and to immerse these small particles in another porous material with a lower or very low specific surface area in which the transfer of matter will be rapid. A material with a high specific surface area is thus obtained in which diffusions and exchanges are rapid, diffusion taking place rapidly in a material with a large pore size up to the small porous particles with a high specific surface area and a small pore size. The entire volume of a material with a high specific surface area is thus rapidly addressed.This high overall specific surface area is achieved by concentrating the stacking of secondary porous particles in the material as much as possible. Advantageously, volume proportions of secondary particles in the final material will be used that are greater than 20%, preferably greater than 40%, and even more preferably greater than 50%. This volume proportion may be close to 60%.

[0435] Such a material, which is optimal for mass transfer, therefore has at least two distinct pore sizes, and is therefore at least bimodal. It can be more easily put into the form of larger solid particles or monoliths which will have high permeability to a fluid, and therefore low pressure drop during operation.

[0436] In particular, they will allow effective diffusional bridging between two neighboring conduits separated by such a material, while presenting a load capacity and therefore high productivity.

[0437] It should be noted in particular that the purpose of this material is to obtain an exchange of matter by diffusion, and not by convection of the fluid in the highly porous structure. Convection is essentially and preferably ensured by the communicating interstices between the grains of the material or by regular channels arranged in a monolithic mass. This allows better control of the desired effects.

[0438] Advantageously, the second population of particles will have an average size or diameter of less than 500 pm, more preferably less than 50 pm, even more preferably less than 5 pm, and preferably less than 2 pm.

[0439] It could be made up of nanoparticles smaller than 0.2 pm.

[0440] Advantageously, this other population may consist of glass beads or microbeads, porous or non-porous polymer, a hydrogel such as crosslinked or non-crosslinked agarose gels for example, polyvinyl pyrrolidone, metal, ceramic, a mineral oxide or mineral gel such as titanium or alumina oxide, vitreous amorphous silica, an ion exchanger, an activated carbon, a zeolite, etc.

[0441] Such devices will find a preferred application in the separation of artificial or natural polymers, peptides, proteins or nucleotides, RNA or RNA segments, DNA or DNA segments, viruses or microorganisms of high or large molar masses. By high molar masses is meant a weight greater than 5000 g / mol, preferably more than 50000 g / mol, even more preferably more than 100000 g / mol.

[0442] The particles of the other population may be non-porous and advantageously have on their external surface adsorption or physisorption sites for said macromolecules such as the antigens of an antibody to be immobilized and recovered. The macromolecules can reach these sites through the large pores opened in the first population which encompasses them.

[0443] We can thus have a high retention capacity for these molecules with great speed. Advantageously, the first population can have a colloidal size or diameter, less than 300 nm, more preferably less than 150 nm, even more preferably less than 50 nm.

[0444] The pore sizes given here are measured by the BET method using nitrogen adsorption.

[0445] Particularly preferably, the average pore size of the coagulum is greater than 5 times the average pore size of the second population of porous particles.

[0446] The materials according to the invention will find a preferred application in chromatography, as a construction material, as an adsorbent, as a catalyst support, for the precision molding of mechanical or optical parts, etc.

[0447] It should be noted that the very low coefficient of expansion of silica, lower than that of INVAR for example, allows them to be used to produce precision castings that are dimensionally stable over a wide range of temperatures and as refractory components.

[0448] EXAMPLES

[0449] Determination of the volume fraction of colloidal particles in the material medium between the porous particles, and the volume fraction of porous particles in the total volume of the material

[0450] Arithmetic formulas for determining the volume fraction of colloidal particles in the material medium between porous particles, and the volume fraction of porous particles in the total volume of the material from the material components are presented in the tables below.

[0451] Characteristics of mesoporous silica particles (porous particles)

[0452] Silica density = 2.2

[0453] Characteristic of silica sol (colloidal particles / nanoparticles)

[0454] Volume of water added to silica sol (B9): 300 ml

[0455]

[0456] Example 1 (excluding invention)

[0457] Example 6 of application WO / 2016 / 050797 has been reproduced. The characteristics of the material obtained are presented below.

[0458] Characteristics of mesoporous silica particles (porous particles)

[0459] Silica density = 2.2

[0460] Characteristic of silica sol (colloidal particles / nanoparticles)

[0461] Volume of water added to silica sol (B9): 300 ml

[0462] The synthesized material has a volume fraction of colloidal particles in the medium of the material between the particles that is too low to fall within the scope of the invention.

[0463] Example 2 (outside the invention) Example 1 of application WO / 2011 / 114017 was reproduced. The characteristics of the material obtained are presented below.

[0464] Characteristics of mesoporous silica particles (porous particles)

[0465] Silica density = 2.2

[0466] Characteristic of silica sol (colloidal particles / nanoparticles) Volume of water added to silica sol (B9): 300

[0467] The synthesized material has a volume fraction of colloidal particles in the medium of the material between the particles that is too low to fall within the scope of the invention.

[0468] Example 3 (excluding invention)

[0469] Example 2 of application WO 2016 / 050797A1 has been reproduced. The characteristics of the material obtained are presented below.

[0470] Characteristics of mesoporous silica particles (porous particles)

[0471] Silica density = 2.2 Characteristic of silica sol (colloidal particles / nanoparticles)

[0472] Volume of water added to silica sol (B9): 300

[0473] The synthesized material has a volume fraction of colloidal particles in the medium of the material between the particles that is too low to fall within the scope of the invention. Example 4

[0474] 20 milliliters of Ludox TM50 silica sol, 50% dry matter by weight, sold by the Grace brand, are poured into a 100 ml beaker with vigorous mechanical stirring. This sol contains 22 nanometer spherical silica nanoparticles suspended in water, stabilized by sodium ions. 6.0 grams of ground glass fiber are gradually added. Then 6.6 grams of silica gel for chromatography with a particle size between 5 and 15 micrometers, containing 15% gypsum for thin layer chromatography, with a pore size of 6.0 nanometers, reference Sigma Aldrich S6503, are added.

[0475] The mixture becomes viscous and pasty due to the high concentration of solid and colloidal particles, following Einstein's equation. The volume proportion of colloidal silica in the free liquid between the silica gel grains is 42%. The volume proportion of silica gel in the total mixed liquid and in the final material is 32%.

[0476] The volume proportion of crushed glass fiber in the total mixed liquid and in the final material is 10.4%.

[0477] The resulting mixture is poured into a polypropylene petri dish which is then tightly sealed with adhesive tape.

[0478] The whole thing is autoclaved for two hours at 120°C.

[0479] After cooling, the petri dish is opened. A rigid, monolithic disc of mesoporous silica has formed. It is heated in an oven for two hours at 105°C.

[0480] The dry disc is rigid, monolithic, and does not show any structural defects or cracks when examined visually, under a binocular microscope or under an optical microscope.

[0481] The shrinkage measured on the material between the wet viscous liquid state and the dried state is less than 0.5% in linear variation, or less than 0.15% in volume variation. This shrinkage, or absence of shrinkage, is measured with a digital caliper across the width of the disc, and by weighing before drying and after rehydration.

[0482] Example 5

[0483] 20 milliliters of Ludox TM50 silica sol at 50% dry matter by weight, marketed by the Grace brand, are poured into a 100 ml beaker with vigorous mechanical stirring. This sol contains 22 nanometer spherical silica nanoparticles suspended in water, stabilized by sodium ions. This liquid is deionized to pH 2 by passing it through an ion exchange resin in Amberlyst 15 acid form.

[0484] 6.0 grams of ground glass fiber are gradually added. Then 6.6 grams of silica gel for chromatography with a particle size between 5 and 15 micrometers, containing 15% of gypsum for thin layer chromatography, with a pore size of 6.0 nanometers, Sigma Aldrich reference S6503, are added.

[0485] The mixture becomes viscous and pasty due to the high concentration of solid and colloidal particles, following the Einstein equation. The volume proportion of colloidal silica in the free liquid between the silica gel grains is 42%. The volume proportion of silica gel in the total mixed liquid and in the final material is 32%. The volume proportion of ground glass fiber in the total mixed liquid and in the final material is 10.4%.

[0486] The resulting mixture is poured into a polypropylene petri dish which is then tightly sealed with adhesive tape.

[0487] The whole thing is autoclaved for two hours at 120°C.

[0488] After cooling, the petri dish is opened. A rigid, monolithic disc of mesoporous silica has formed. It is heated in an oven for two hours at 105°C.

[0489] The dry disc is rigid, monolithic, and does not show any structural defects or cracks when examined visually, under a binocular microscope or under an optical microscope.

[0490] The shrinkage measured on the material between the wet viscous liquid state and the dried state is less than 0.1% in linear variation, or less than 0.3% in volume variation. This shrinkage, or absence of shrinkage, is measured with a digital caliper across the width of the disc, and by weighing before drying and after rehydration.

[0491] Example 6: Synthesis of a monolith

[0492] Material

[0493] 3 beakers of 50 ml

[0494] 2 pipettes: 10 ml and 100 ml

[0495] Plastic petri dish with lid

[0496] 1 autoclave with a basket

[0497] 1 magnetic stirrer + magnetic bar

[0498] Preparation of reagents

[0499] • Ludox TM50 (colloidal Si sol) (A)

[0500] • Crushed fiberglass (B)

[0501] • Silica gel Silicycle 5-25 pm (C)

[0502] • Hydrazine di-nitrate (1M) (D)

[0503] • Permuted water (E)

[0504] Operating mode:

[0505] • Dissolution of B in A with stirring (speed 3) at T amb (F) (milky gray color)

[0506] • Very gradual addition of C to F while stirring (speed 3), reduce stirring to 2 when the mixture reaches a viscous consistency, leave the mixture to homogenize for 2 min. Weigh any remaining silica gel (G)

[0507] • Addition of D to G with stirring (2) at T amb for 10 min. • Pour the resulting paste into a tared petri dish marked with a test number.

[0508] • Place the box in the autoclave basket preheated to Patm (marker 5)

[0509] • The whole thing is brought to 120°C (marker 3) for 1 hour in an autoclave. The stopwatch is started as soon as the autoclave valve reopens (approx. 5 min).

[0510] • After 1 hour, leave to cool for approx. 10 minutes, do not release the pressure (risk of the monolith bursting)

[0511] Heat treatments

[0512] • Drying in a ventilated oven at 95°C for 1 hour and 1 hour at 105°C. (remove the lid from the box during drying, keep it for weighing)

[0513] Example 7: Study of the drying curve of a monolith as a function of the sol and gel silica load with TM50 sol (A)

[0514] The tests were carried out according to the procedure given in example 6. gSiO2 represents the quantity of powdered silica gel added.

[0515] Vol pore its pore volume BET.

[0516] Water Vol is the volume of water in the test

[0517] ED is the volume of exchanged water

[0518] SiO2 Weight is the weight of colloidal silica contained in the sol.

[0519] VolEau resid is the volume of interstitial water between the silica gel particles kg SiO2sol / l eau res is the weight of colloidal silica per unit volume of interstitial water

[0520] The results are shown in Figure 1 (Estimated silica density 1.15 cm 3 / g; Start of the plateau for a dilution water value of 4 ml; on the abscissa the weight in SiO2 sol, on the ordinate on the left the ratio kg SiO2 / L water and on the right the Vol eau resid) and in the table below.

[0521] The resulting curve has two zones.

[0522] It is observed that increasing the initial proportion of sol in the aqueous phase (from 10 to 40%) initially has no influence on the quantity of silica gel that can be added to the medium. In a second phase, (from 60 to 100%) the maximum quantity of silica that can be added decreases with the concentration of the sol. The calculation shows that in the first sequence the concentration of silica sol in the interstitial aqueous phase decreases drastically, while it is approximately constant in the second phase. This is easily explained: in the first sequence the volume of sol particles is too low to reach a sufficient concentration in the aqueous phase, and the volume of silica that can be added reaches its natural limit in a free liquid medium. The fluid will not be bound after drying by a sufficient concentration of sol particles to create a continuum, and cracks will appear.We are not in the conditions leading to a solid according to the invention.

[0523] In the second part of the curve, on the contrary, the sols are sufficiently loaded with colloidal solid particles so that they arrive at a compact stack under the dehydrating effect of the silica gel, and can be dried without shrinkage or fractures. A solid is obtained according to the invention. It is noted that the more concentrated the sol, the less silica gel must be added to obtain this dehydrating effect on the one hand, and that the final concentration of colloidal particles of the sol in the interstitial residual solvent is approximately constant. It can be seen from the previous table that the volume fraction of colloidal particles in the middle of the material between the particles is greater than 20% as soon as the dilution of the soil becomes greater than approximately 50%, which correlates perfectly with the curve in figure 1.

[0524] Example 8: Study of the drying curve of the monolith as a function of the sol and gel silica load with Bindzil 40 / 170 sol (polydisperse) instead of TM50 sol (A)

[0525] The tests were carried out according to the procedure given in example 2. Adjustment of the initial pH to 2 / 7 / 9 for 30 and 40% by weight in SiC>2 in the soil pHi corresponds to the adjustment of the pH on the soil itself, pHf corresponds to the pH of the final medium after addition of silica gel.

[0526] Mechanical resistance tests

[0527] The mechanical resistance tests reported in this text are conducted by measuring the force required to obtain the rupture of a final monolith sample of thickness 3 mm and square shape of 10 mm times 10 mm under the action of a conical punch with an angle at the top of 120 opening. Transmission electron microscopy photos of the obtained material are shown in Figures 2 (colloid part) and 3 (colloid and silica gel part).

[0528] The nitrogen adsorption / desorption isotherms and the adsorption and desorption diameters are respectively presented in Figures 4 (abscissa: relative pressure; ordinate: adsorbed volume in mL / g), 5 (abscissa: dV / dD volume in mL / g; ordinate: average diameter in nm) and 6 (abscissa: dV / dD volume in mL / g; ordinate: average diameter in nm). It is noted that the use of a polydisperse silica sol increases the mechanical strength of the final material.

[0529] Example 9: Study of the drying curve of the monolith as a function of the sol and gel silica load with Bindzil sol 30 / 360 (0= 7nm) instead of TM50 sol (A) The tests were carried out following the procedure given in example 2. Adjustment of the initial pH to 2 / 7 / 9 for 30 and 40% by weight in SiO2 mechanical resistance tests The nitrogen adsorption / desorption isotherms and the adsorption and desorption diameters are respectively presented in Figures 7 (abscissa: relative pressure; ordinate: adsorbed volume in mL / g), 8 (abscissa: dV / dD volume in mL / g; ordinate: mean diameter in nm) and 9 (abscissa: dV / dD volume in mL / g; ordinate: mean diameter in nm).

[0530] Best results are obtained at pH 2 and 11 with a bimodal distribution.

[0531] A transmission electron microscopy photograph of the obtained material (colloid part; 7b-3 Bindzil 30360 pH 2) is shown in Figure 10.

[0532] Example 10: Effect of source change of Silica Bindzil 30 / 360 (0= 7nm) Adjustment of the initial pH to 2 / 7 / 9 for 30 and 40% wt in SiC>2 mechanical resistance tests The nitrogen adsorption / desorption isotherms and the adsorption and desorption diameters are respectively presented in Figures 11 (abscissa: relative pressure; ordinate: adsorbed volume in mL / g), 12 (abscissa: dV / dD volume in mL / g; ordinate: mean diameter in nm) and 13 (abscissa: dV / dD volume in mL / g; ordinate: mean diameter in nm).

[0533] Best results are obtained at pH 2 and 11 with a bimodal distribution.

[0534] It is noted that the use of this soil allows the obtaining of higher specific surfaces of the final material, of the order of 300 m2 / g.

[0535] Example 11: Production of a material from a suspension of silica sol in a polyol.

[0536] 20 ml of TM50 sol from Grace purchased from Sigma-Aldrich are first deionized using a cationic ion exchanger.

[0537] The 20 ml are added to a 150 ml rotary evaporator flask with 15 ml of Glycerin. The whole is stirred and then evaporated in the rotary evaporator at 120 rpm in an oil bath heated according to the temperature program below.

[0538] The vacuum in the device enclosure is set at 25 mbar.

[0539] The oil bath temperature is programmed at 75°C for 30 minutes.

[0540] At the end of this program, 14 g of water vapor evaporated, i.e. all the water contained in the TM50 intake.

[0541] To the residual clear and viscous liquid, 8.0 g of Fuji Silysia silica, with a particle size of 3 pm, an average pore size of 6 nm and a specific surface area of ​​450 m2 / g, are added intimately using a spatula. The pore volume is 0.8 cm3 / g.

[0542] The mixture is introduced into a Teflon mold measuring 30mm x 20mm and 8mm thick and closed with a PTFE lid.

[0543] The whole thing is placed in the autoclave at 120°C for two hours.

[0544] The medium takes a solid form. It is dried under vacuum at 200°C for 16 h. The test piece shows no shrinkage.

[0545] The resulting test piece, removed from the mold, is pyrolyzed at 500°C for 12 hours after a programmed temperature increase of 1°C per minute from ambient temperature.

[0546] The specific surface area of ​​the product obtained is 251 m2 / g. Example 12: Production of a material from a suspension of silica sol in a polyol.

[0547] 20 ml of HS30 sol from Grace purchased from Sigma-Aldrich are first deionized using a cationic ion exchanger.

[0548] The 20 ml are added to a 150 ml rotary evaporator flask with 15 ml of Glycerin. The whole is stirred and then evaporated in the rotary evaporator at 120 rpm in an oil bath heated according to the temperature program below.

[0549] The vacuum in the device enclosure is set at 25 mbar.

[0550] The oil bath temperature is programmed at 75°C for 30 minutes.

[0551] At the end of this program, 14 g of water vapor evaporated, i.e. all the water contained in the TM50 intake.

[0552] To the residual clear and viscous liquid, 10 g of Fuji Silysia silica, with a particle size of 3 pm, an average pore size of 6 nm and a specific surface area of ​​450 m2 / g, are added thoroughly using a spatula.

[0553] The mixture is introduced into a Teflon mold measuring 30mm x 20mm and 8mm thick and closed with a PTFE lid.

[0554] The whole thing is placed in the autoclave at 120°C for two hours.

[0555] The medium takes a solid form. It is dried under vacuum at 200°C for 16 h. The test piece shows no shrinkage.

[0556] The resulting test piece, removed from the mold, is pyrolyzed at 500°C for 12 hours after a programmed temperature increase of 1°C per minute from ambient temperature.

[0557] The specific surface area of ​​the product obtained is 345 m2 / g.

[0558] Example 13: Production of a material from a suspension of silica sol in a polyol.

[0559] 20 ml of SM30 sol from Grace purchased from Sigma-Aldrich are first deionized using a cationic ion exchanger.

[0560] The 20 ml are added to a 150 ml rotary evaporator flask with 15 ml of Glycerin. The whole is stirred and then evaporated in the rotary evaporator at 120 rpm in an oil bath heated according to the temperature program below.

[0561] The vacuum in the device enclosure is set at 25 mbar.

[0562] The oil bath temperature is programmed at 75°C for 30 minutes.

[0563] At the end of this program, 14 g of water vapor evaporated, representing all the water contained in the TM50 intake. 10 g of Fuji Silysia silica, with a particle size of 3 pm, an average pore size of 6 nm and a specific surface area of ​​450 m2 / g, were added to the remaining clear and viscous liquid using a spatula.

[0564] The mixture is introduced into a Teflon mold measuring 30mm x 20mm and 8mm thick and closed with a PTFE lid.

[0565] The whole thing is placed in the autoclave at 120°C for two hours.

[0566] The medium takes a solid form. It is dried under vacuum at 200°C for 16 h. The test piece shows no shrinkage.

[0567] The resulting test piece, removed from the mold, is pyrolyzed at 500°C for 12 hours after a programmed temperature increase of 1°C per minute from ambient temperature.

[0568] The specific surface area of ​​the product obtained is 398 m2 / g.

[0569] Example 14: Production of a precursor from a suspension of silica sol in glyceryl methacrylate.

[0570] 20 ml of TM50 sol from Grace purchased from Sigma-Aldrich are first deionized using a cationic ion exchanger.

[0571] The 20 ml are added to a 150 ml rotary evaporator flask to 15 ml of glyceryl mono methacrylate supplied by Polyscience, and 15 mg of hydroquinone monomethyl ether supplied by Sigma Aldrich.

[0572] The whole is stirred then evaporated in the rotary evaporator at a rate of 120 revolutions / min in an oil bath heated according to the temperature program below.

[0573] The vacuum in the device enclosure is set at 25 mbar.

[0574] The oil bath temperature is programmed at 60°C for 30 minutes.

[0575] At the end of this program, 14 g of water vapor evaporated, i.e. all the water contained in the TM50 intake.

[0576] To the residual clear and viscous liquid, 8.0 g of Fuji Silysia silica, with a particle size of 3 pm, and 0.6 g of Luperox 26 radical initiator supplied by Arkema are added thoroughly using a spatula.

[0577] Example 15: Production of a molded material from a precursor in glyceryl methacrylate.

[0578] The suspension obtained in example 14 is introduced into a Teflon mold measuring 30mm x 20mm and 8mm thick and closed with a PTFE lid.

[0579] The medium is placed in an autoclave in its Teflon mold at 120°C for two hours. The medium takes on a solid form. It is heated to 200°C for 16 hours. The acrylic monomer polymerizes. The test piece shows no shrinkage.

[0580] The resulting test piece, removed from the mold, is pyrolyzed at 500°C for 12 hours after a programmed temperature increase of 1°C per minute from ambient temperature.

[0581] It should be noted that the polymerized specimen before pyrolysis can be machined according to any desired structure with very great finesse of detail and freedom of form.

[0582] Example 16: Production of an injected material from a suspension of powdered silica and silica sol in glyceryl methacrylate.

[0583] The suspension obtained in example 14 is injected into a stainless steel mold made up of two half-shells with a capacity of 12 ml.

[0584] The mold is heated to 120°C for two hours, then to 200°C for 16 hours.

[0585] The resulting test piece, removed from the mold, is pyrolyzed at 500°C for 12 hours after a programmed temperature increase of 1°C per minute from ambient temperature.

[0586] Example 17: Production of a sintered injected material.

[0587] The material obtained in Example 15 is sintered at 1350°C for 1 hour after a programmed temperature increase of 5°C per minute from ambient.

[0588] The resulting material is transparent, does not contain any gas inclusions visible to the naked eye, and has retained its original shape without loss of detail.

[0589] Example 18: Production of a sintered injected material.

[0590] 20 ml of TM50 soil from Grace purchased from Sigma-Aldrich taken without prior deionization.

[0591] The 20 ml are added to a 150 ml rotary evaporator flask to 15 ml of glyceryl mono methacrylate supplied by Polyscience, and 15 mg of hydroquinone monomethyl ether supplied by Sigma Aldrich.

[0592] The whole is stirred then evaporated in the rotary evaporator at a rate of 120 revolutions / min in an oil bath heated according to the temperature program below.

[0593] The vacuum in the device enclosure is set at 25 mbar.

[0594] The oil bath temperature is programmed at 60°C for 30 minutes.

[0595] At the end of this program, 14 g of water vapor evaporated, i.e. all the water contained in the TM50 intake.

[0596] To the residual clear and viscous liquid, 8.0 g of Fuji Silysia silica, with a particle size of 3 pm, and 0.6 g of Luperox 26 radical initiator supplied by Arkema are added intimately using a spatula. The medium is placed in an autoclave in its Teflon mold at 120 °C for two hours.

[0597] The medium takes on a solid form. It is heated to 200°C for 16 hours. The acrylic monomer polymerizes. The test piece shows no shrinkage.

[0598] The resulting test piece, removed from the mold, is pyrolyzed at 500°C for 12 hours after a programmed temperature increase of 1°C per minute from ambient temperature.

[0599] The material is soaked by post addition of Sigma Aldrich tetraethoxy silane premixed with four molar equivalents of water and stirred on a magnetic stirrer until a homogeneous mixture is obtained.

[0600] The medium is brought to 60°C for 12 hours and dried.

[0601] The material has a breaking strength 1.56 times higher than that of the material obtained without post addition.

[0602] Note that the post addition step can be repeated as many times as necessary.

[0603] Example 19: Production of a material from a suspension of silica sol in hydroxyethyl methacrylate.

[0604] 20 ml of TM50 sol from Grace purchased from Sigma-Aldrich are first deionized using a cationic ion exchanger.

[0605] The 20 ml are added to a 1000 ml rotary evaporator flask, 444 ml of 99.8% ethyl alcohol without additives for analysis from the company Sigma-Aldrich.

[0606] The whole is stirred then evaporated in the rotary evaporator at a rate of 120 revolutions / min.

[0607] The vacuum in the device enclosure is set at 40 mbar.

[0608] The oil bath temperature is programmed at 40°C for 60 minutes.

[0609] At the end of this program 352 g of condensed water vapor and ethanol evaporated.

[0610] 5 g of dry 3 Angstrom molecular sieve are added to the residual liquid. The mixture is left to stir on a rotary evaporator for 12 hours at a temperature of 60°C and ambient pressure.

[0611] 8.0 g of Fuji Silysia silica, with a particle size of 3 pm, an average pore size of 6 nm and a specific surface area of ​​450 m2 / g, are intimately incorporated into the viscous medium thus obtained, separated from the molecular sieve grains, using a spatula.

[0612] Into the residual clear and viscous medium, 15 ml of 2-hydroxyethyl methacrylate supplied by Sigma Aldrich and 15 mg of hydroquinone monomethyl ether supplied by Sigma Aldrich are intimately incorporated.

[0613] The whole is stirred and then evaporated in the rotary evaporator at a rate of 120 revolutions / min. The vacuum in the apparatus enclosure is set at 25 mbar.

[0614] The oil bath temperature is programmed at 60°C for 15 minutes.

[0615] 0.6 g of Azobis isobutyronitrile (AIBN) initiator supplied by Sigma Aldrich is added quickly and intimately to this mixture cooled to 0°C.

[0616] The mixture is introduced into a Teflon mold measuring 30mm x 20mm and 8mm thick and closed with a PTFE lid.

[0617] The whole thing is placed in a thermostatically controlled enclosure at 70°C for two hours.

[0618] The environment takes on a solid form.

[0619] The resulting test piece, removed from the mold, is pyrolyzed at 500°C for 12 hours after a programmed temperature increase of 1°C per minute from ambient temperature.

[0620] It should be noted that the polymerized test piece before pyrolysis can be molded, injected, extruded according to any desired structure with very fine detail and freedom of form. The extrusion could, for example, take the form of a fusible filament for a 3D printer, with pyrolysis taking place on the printed part.

[0621] Example 20: Production of a material from a suspension of silica sol in hydroxyethyl methacrylate.

[0622] 20 ml of TM50 sol from Grace purchased from Sigma-Aldrich are first deionized using a cationic ion exchanger.

[0623] The 20 ml are added to a 500 ml rotary evaporator flask to 444 ml of 99.8% ethyl alcohol without additives for analysis from the company Sigma-Aldrich.

[0624] The whole is stirred then evaporated in the rotary evaporator at a rate of 120 revolutions / min.

[0625] The vacuum in the device enclosure is set at 40 mbar.

[0626] The oil bath temperature is programmed at 40°C for 60 minutes.

[0627] At the end of this program 352 g of water vapor and ethanol condensates evaporated.

[0628] 5 g of dry 3 Angstrom molecular sieve are added to the residual liquid. The mixture is left to stir on a rotary evaporator for 12 hours at a temperature of 60°C and ambient pressure.

[0629] 8.6 g of Fuji Silysia silica, with a particle size of 3 pm, an average pore size of 6 nm and a specific surface area of ​​450 m2 / g, are intimately incorporated into the viscous medium thus obtained, separated from the molecular sieve grains, using a spatula. The pore volume is 0.8 cm3 / g.

[0630] Into the residual clear and viscous medium, 15 ml of 2-hydroxyethyl methacrylate supplied by Sigma Aldrich and 15 mg of hydroquinone monomethyl ether supplied by Sigma Aldrich are intimately incorporated. The mixture is stirred and then evaporated in the rotary evaporator at a rate of 120 rpm.

[0631] The vacuum in the device enclosure is set at 25 mbar.

[0632] The oil bath temperature is programmed at 60°C for 15 minutes.

[0633] This produces a so-called precursor medium.

[0634] A mixture of 0.6 ml of acetone supplied by Sigma Aldrich and 0.6 g of Irgacure-2959 photochemical initiator supplied by Sigma Aldrich is prepared.

[0635] This solution is added intimately and quickly to the precursor medium.

[0636] A batch of 3 glass microscopy slides, 20 mm wide and 70 mm long, are slowly soaked and extracted into this final medium.

[0637] The first blade is exposed to a flow of Ultraviolet rays generated by a UV lamp Reference K.LUV.INSPEC from the company FLUOTECHNIK positioned axially at 38 cm and generating 4500 pW / cm 2 , for 30 seconds.

[0638] The second blade is covered with a mask comprising a honeycomb pattern with sides of 2 mm and line thickness of 0.1 mm and exposed to a flux of Ultraviolet rays generated by a UV lamp Reference K.LUV.INSPEC from the company FLUOTECHNIK positioned axially at 38 cm and generating 4500 pW / cm 2 , for 30 seconds.

[0639] The third blade serves as a witness.

[0640] The three slides are revealed by rinsing with demineralized water.

[0641] The first blade has a layer of homogeneous polymerized material.

[0642] The second blade shows the hexagonal pattern of the masking deposited on the blade.

[0643] The third blade shows no deposit on the bare glass.

[0644] Slides 1 and 2 are pyrolyzed at 500°C for 2 hours to reveal the photo-crosslinked structure in the form of a silica gel film. Production of a material from a suspension of silica sol in a polyol.

[0645] 20 ml of Levasil® CS40-68 P sol from Nouryon are added intimately using a spatula 4.3 g of Fuji Silysia silica, with a particle size of 3 pm, an average pore size of 6 nm and a specific surface area of ​​450 m2 / g. The pore volume is 0.8 cm3 / g The mixture is introduced into a Teflon mold measuring 30mm x 20mm and 8mm thick and closed with a PTFE lid.

[0646] The whole thing is dried at room temperature for 48 hours.

[0647] The medium takes a solid form. It is then dried in an oven at 105 °C for 16 h. The test piece shows no shrinkage. Analyzed by the BET nitrogen absorption method, the material is bimodal in terms of pore size, a first group of mesoporous around 6 nm, a second group of mesopore distributed between 10 and 50 nm.

[0648] Example 22: Production of a material from a suspension of silica sol in a polyol.

[0649] 40 ml of TM50 sol from Grace purchased from Sigma-Aldrich are first deionized using a cationic ion exchanger.

[0650] The 40 ml is added to a 150 ml rotary evaporator flask with 15 ml of Glycerin. The whole is stirred and then evaporated in the rotary evaporator at 120 rpm in an oil bath heated according to the temperature program below.

[0651] The vacuum in the device enclosure is set at 25 mbar.

[0652] The oil bath temperature is programmed at 60°C for 60 minutes.

[0653] At the end of this program, 28 g of water vapor evaporated, i.e. all the water contained in the TM50 intake.

[0654] To the residual clear and very viscous fluid, the consistency of honey, 9 g of non-porous silica sand powder, with a grain size of 30 μm, is added intimately using a spatula. The mixture is introduced into a Teflon mold measuring 30 mm x 20 mm and 8 mm thick and closed with a PTFE lid.

[0655] The whole thing is placed in the autoclave at 120°C for two hours.

[0656] The medium takes a solid form. It is dried under vacuum at 200°C for 16 h. The test piece shows no shrinkage.

[0657] The resulting test piece, removed from the mold, is pyrolyzed at 500°C for 12 hours after a programmed temperature increase of 1°C per minute from ambient temperature.

[0658] The resulting specimen shows no shrinkage or cracking.

[0659] Example 23: Production of a material by micromolding from a suspension of silica sol and porous silica particles

[0660] 20 milliliters of Ludox TM50 silica sol, 50% dry matter by weight, marketed by the Grace brand, are poured into a 100 ml beaker with vigorous mechanical stirring. This sol contains spherical silica nanoparticles of 22 nanometers suspended in water, stabilized by sodium ions. 6.0 grams of ground glass fiber are gradually added. Then 6.6 grams of silica gel for chromatography with a particle size between 5 and 15 micrometers, containing 15% plaster for thin layer chromatography, with a pore size of 6.0 nanometers, reference Sigma Aldrich S6503, are added. The mixture becomes viscous and pasty due to the high concentration of solid and colloidal particles, following the Einstein equation. The volume proportion of colloidal silica in the free liquid between the silica gel grains is 42%.The volume proportion of silica gel in the total mixed liquid and in the final material is 32%.

[0661] The volume proportion of ground glass fiber in the total mixed liquid, called Mixture Z, and in the final material is 10.4%.

[0662] The replicated micro face carries the optics of a printed micro Fresnel magnifier reference LHP.FCB of approximately 8x5 cm from the company LESAFRANCE.

[0663] On the face bearing the active pattern of the Fresnel magnifier, 1.5 g of the Z mixture are uniformly deposited. This film of approximately 250 μm is left to dry at room temperature in a desiccator for twenty-four hours. A film of dry and mesoporous siliceous material is easily separated from the mold. Such a process can be used to produce printed channels for example, and the films obtained before, during or after drying can be rolled, stacked, etc. to produce any desired shape by microfluidic or optical devices for example. In the case of optical devices, sintering of the parts at 1350 °C will be advantageous to eliminate their porosity and make them transparent. The sintered or unsintered parts can be used as molds for polymeric, ceramic or metallic materials due to the very high melting temperature of silica and its dimensional stability (very low coefficient of thermal expansion). Production of a material by micromolding from a suspension of silica sol and porous silica particles

[0664] 20 milliliters of Ludox TM50 silica sol, 50% dry matter by weight, sold by the Grace brand, are poured into a 100 ml beaker with vigorous mechanical stirring. This sol contains 22 nanometer spherical silica nanoparticles suspended in water, stabilized by sodium ions. 6.0 grams of ground glass fiber are gradually added. Then 6.6 grams of silica gel for chromatography with a particle size between 5 and 15 micrometers, containing 15% gypsum for thin layer chromatography, with a pore size of 6.0 nanometers, reference Sigma Aldrich S6503, are added.

[0665] The mixture becomes viscous and pasty due to the high concentration of solid and colloidal particles, following the Einstein equation. The volume proportion of colloidal silica in the free liquid between the silica gel grains is 42%. The volume proportion of silica gel in the total mixed liquid and in the final material is 32%. To this mixture is added 50 ml of a polyvinyl alcohol (PVA) solution with a molecular weight by weight of 89000 and a degree of hydrolysis greater than 99% containing 300 g of PVA per liter.

[0666] The volume proportion of ground glass fiber in the so-called Y-Mix and in the final material is 10.4%.

[0667] The replicated micro face carries the optics of a printed micro Fresnel magnifier reference LHP.FCB of approximately 8x5 cm from the company.

[0668] On the face bearing the active pattern of the Fresnel magnifying glass, 1.5 g of the Y mixture are uniformly deposited. This film of approximately 250 μm is left to dry at room temperature in a desiccator for twenty-four hours. A film of dry, mesoporous siliceous material bound by the PVA is easily separated from the mold.

[0669] The resulting film is heated to 500°C in air to pyrolyze the PVA and leave a film of mesoporous material.

[0670] Such a process can be used to produce printed channels for example, and the films obtained before, during or after drying can be rolled up, stacked, etc. to produce any desired shape by microfluidic or optical devices for example.

[0671] Example 25

[0672] To 80 ml of Ludox SM30 sol from Grace deionized by a cation exchange resin in H+ form, 40 g of Silicycle silica gel are added while stirring.

[0673] The test is carried out for four silica gels with particle size 20-45 pm and references S10020C, S10020E, S10020M, S10020P, with pore sizes of 70, 100, 300, and 500 Angstrom respectively.

[0674] These samples are poured into polypropylene test tubes, their viscosity is measured immediately after mixing, and they are left to stand for 24 hours. The gel state is characterized for the first two test tubes. The last two remain fluid with unchanged viscosity. Example 26

[0675] 20 milliliters of silica sol with a nanoparticle size of 70 nm and 50% dry matter by weight, marketed by the Nouryon brand, are poured into a 100 ml beaker with vigorous mechanical stirring. This sol contains spherical silica nanoparticles of 70 nanometers suspended in water, stabilized by sodium ions. 10 grams of silica gel for chromatography with a particle size between 5 and 15 micrometers, containing 15% plaster for thin layer chromatography, with a pore size of 6.0 nanometers, reference Sigma Aldrich S6503, are then added.

[0676] The mixture becomes viscous and pasty due to the high concentration of solid and colloidal particles, following Einstein's equation. The volume proportion of colloidal silica in the free liquid between the silica gel grains is 42%.

[0677] The resulting mixture is poured into a polypropylene petri dish.

[0678] The Petri dish is opened. It is placed in an oven for two hours at 105°C. A rigid, monolithic disk of macroporous and mesoporous silica has formed.

[0679] The dry disc is rigid, monolithic, and does not show any structural defects or cracks when examined visually, under a binocular microscope or under an optical microscope.

[0680] The shrinkage measured on the material between the wet viscous liquid state and the dried state is less than 0.5% in linear variation, or less than 0.15% in volume variation. This shrinkage, or absence of shrinkage, is measured with a digital caliper across the width of the disc, and by weighing before drying and after rehydration.

[0681] This sample has two pore sizes, small pores of 6 nanometers corresponding to the silica gel particles, large pores of 70 nanometers corresponding to the colloid gel and encompassing the silica gel particles.

[0682] This allows access to silica gel particles by molecular diffusion through large pores. In particular, the phenomenon known as diffusion bridging is facilitated.

[0683] Example 27

[0684] 200 milliliters of titanium oxide sol with a nanoparticle size of 150 nm and a dry matter content by weight, marketed by the Sigma Aldrich brand, reference 700347, are poured into a 500 ml flask of a rotary evaporator. This sol is concentrated by vacuum evaporation at 60 °C to a dry matter content of 60%. 20 milliliters of this concentrated sol are poured into a 100 ml beaker with vigorous mechanical stirring. 50 grams of glass microbeads with diameters between 5 and 15 micrometers containing a specific antigen grafted onto their surface are then added.

[0685] The volume proportion of colloidal titanium dioxide in the free liquid between the glass grains is 32%. The resulting mixture is poured into a polypropylene Petri dish.

[0686] The Petri dish is opened. It is placed in an incubator for two hours at 25°C under vacuum. A rigid, monolithic disk of macroporous titanium dioxide has formed.

[0687] The dry disc is rigid, monolithic, and does not show any structural defects or cracks when examined visually, under a binocular microscope or under an optical microscope.

[0688] This sample has large pores of 150 nm corresponding to the gel of the colloid encompassing the glass particles.

[0689] A monoclonal antibody can thus access glass particles by molecular diffusion through large pores. It can be attached to an antigen attached to the glass beads with a high loading capacity. Production of a material from a suspension of boehmite soil and porous activated alumina particles

[0690] 250 ml of DEQUASOL LC boehmite suspension, with a crystallite size of 10-12 nm supplied by DEQUACHIM, Belgium, are brought to a weight concentration of 50% by weight by passing through a rotary evaporator.

[0691] 20 ml of the resulting suspension are immediately brought into contact, while stirring, with 20 g of neutral activated alumina reference 199974 from Sigma Aldrich gradually added to the mixture.

[0692] The resulting mixture is introduced into a Teflon mold measuring 30mm x 20mm and 8mm thick and closed with a PTFE lid.

[0693] The whole thing is placed in the autoclave at 120°C for two hours.

[0694] The medium takes a solid form. It is dried under vacuum at 200°C for 16 h. The test piece shows no shrinkage.

Claims

CLAIMS 1. Solid porous material characterized in that it comprises: - a first population of particles made up of nanoparticles smaller than 300 nm; - at least one other population of particles comprising one or more components distributed according to one or more particle sizes, the other population of particles representing from 20% to 80% of the total volume of the material, in which the first population of particles represents from 25% to 85% of the volume of the material present between the particles of the other population of particles.

2. Solid porous material according to claim 1 characterized in that it comprises: - a first population of particles made up of nanoparticles smaller than 300 nm; - a second population of particles consisting of porous particles having a porosity ranging from 10% to 90% by volume, the second population of particles representing from 20% to 80% of the total volume of the material, wherein the first population of particles represents from 25% to 85% of the volume of the material present between the porous particles of the second population of particles.

3. Material according to claim 2 characterized in that the first population of particles represents more than 45% of the volume of the material present between the porous particles of the second population of particles, advantageously more than 50%, even more advantageously more than 55%, and more preferably more than 60% of this volume.

4. Material according to claim 2 or 3 in which the nanoparticles of the first population have a size greater than one time, preferably greater than two times, even more preferably greater than ten times the average diameter of the pores of the second population of particles.

5. Material according to one of claims 2 to 4 in which the first population of particles results from a sol based on aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, rare earth oxide such as yttrium, cerium or lanthanum, boron oxide, iron oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, germanium oxide, phosphorus oxide, lithium oxide, potassium oxide, sodium oxide, niobium oxide, copper oxide or a mixture thereof.

6. Material according to any one of claims 2 to 4, characterized in that the first population of particles consists of organic nanoparticles.

7. Material according to any one of claims 2 to 4, characterized in that the first population of particles consists of organometallic nanoparticles.

8. Material according to claim 2, 3, 4 or 5 wherein the first population of particles results from a sol based on aluminum oxide or silicon oxide.

9. Material according to any one of claims 2 to 8 wherein the second population of particles is particles of silica gel, activated alumina, silico aluminate, porous metal, glass, zeolites, carbon black, activated carbon, pumice stone, kieselgur, or porous organic or organometallic polymers.

10. Material according to any one of the preceding claims, characterized in that the second population of particles is physically or chemically reactive and comprises or consists of a mineral filler, serving as an agent for a separation technique such as a stationary phase for chromatography, as a catalyst, or as a filler consumable by a chemical reaction.

11. Material according to any one of the preceding claims, characterized in that the second population of particles is physically or chemically reactive and comprises or consists of an organic or biological filler serving as an agent of a chemical or biological reaction, such as an ion exchanger, a protein, a fragment of DNA or RNA or an immobilized enzyme.

12. Material according to any one of claims 1 to 6 further comprising a filler of fibers, microfibers or nanofibers.

13. Material according to any one of claims 1 to 7 having a proportion of mesopores between 2 and 50 nanometers greater than 90% by volume.

14. Process for preparing a porous material according to claim 2, characterized in that it comprises the following steps: (a) providing a sol consisting of nanoparticles of size less than 300 nm dispersed in a liquid; (b) providing porous solid particles having a porosity ranging from 10% to 90% by volume, the pores of which have a size that does not allow soil nanoparticles to penetrate therein, the porous solid particles being wettable by soil liquid; (c) addition of the porous solid particles to the soil so as to achieve a volume fraction of nanoparticles in the liquid greater than 20%; (d) drying.

15. Method for manufacturing a material according to claim 1 characterized in that it comprises the following steps: (a) providing a sol consisting of particles of size d1, in particular nanoparticles of size d1, concentrated at more than 40%, and preferably at more than 45% by volume of solid particles; (b) supply of another population of solid particles (d) adding said other population of solid particles to the soil; (e) drying.

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