HK1140714A - Methods and devices using a shrinkable support for porous monolithic materials - Google Patents

Description

Method and apparatus for applying shrinkable support material to porous monolith

Technical Field

The present invention relates generally to components for analytical or preparative applications and chemical treatments or catalysis, and to methods of making and using the same.

Background

Porous monoliths have a wide range of applications such as filtration, adsorption, and catalysis. Such materials are often installed and contained within and in intimate contact with a support structure, such as a containment tube, which simultaneously provides support and protection for the porous media and, for some applications, restricts the flow of liquid or gas. In order for a particular process to function properly, it is important to restrict the flow of fluids (or gases) through the porous monolith and to minimize their flow around the porous monolith around which they flow as they flow in the interstices between the porous monolith and its supporting structure. Insufficient contact or poor control of contact between the porous material and the fluid (or gas) and any components present therein, diffusion broadening of chromatographic peaks, insufficient adsorption or catalysis, etc., due to leakage through the gaps between the porous monolith and its supporting structure. To avoid these problems, it is desirable to have the liquid or gas in intimate contact with the edges of the porous monolith and its supporting structure to control the contact between the fluid and its components and the porous monolith as desired.

Depending on the particular application and the particular materials appropriately selected for the application, various assembly methods may be employed to produce structures suitable for the application, including porous monoliths and support structures associated therewith. However, many of these structures suffer from excessive leakage around the edges due to shrinkage of the porous monolith away from its associated support. For example, inorganic materials such as glass or ceramics are often used due to their resistance to solvents and high temperatures. The fabrication of related structures from these materials often requires the use of high temperature processing steps. For this reason and others, porous materials tend to shrink significantly during the manufacturing process. If a rigid support material is used, the interior wall appearance may exhibit excessive clearance after all manufacturing steps are completed, resulting in the porous material not being secured to its support structure.

One approach to addressing these problems is to provide a shrinkable support that can be shrunk into intimate contact with the porous monolith that it contains or is associated with. Shrinkable polymers are well known and widely used. They are used in sheet form to form vacuum and "shrink wrap". Protective, insulating and/or supporting outer layers of near-cylindrical components are also often formed in tubular form, especially in electrical applications. However, such polymeric materials cannot be used in many applications because the thermal and/or chemical resistance of such materials cannot be adapted to such applications.

In the field of precision metal manufacturing, a common technique is to make the outer part just slightly smaller in its inner dimension than the outer dimension of the inner part when making it. The outer part is heated and its size expands just enough to insert the inner part. Upon cooling, the two components form an "interference" fit, are in intimate contact, do not leak, and can be joined without the use of a bonding agent. However, this technique is only applicable when the dimensions of the two parts to be assembled can be held to extremely close tolerances, which is not possible with porous monolithic materials.

Similar techniques are used to form electrical or other metal feedthroughs (feedthru) on the glass walls of vacuum tubes, bulbs, etc. A metal rod or wire is inserted through the hole or glass tube and the glass is then heated until it softens and the hole or gap shrinks around the metal forming a vacuum seal. Thus, while it is known in the art to provide a seal for metal parts using glass as the shrinkable medium, this technique has not been used for porous monoliths to form a seal between the containing or supporting wall and the porous monolith. In contrast, glass has been used as a container and mold for producing porous monoliths by the sol-gel process, but after drying and firing, the porous monolith becomes loose on the support. This problem has not been solved.

Sol-gel methods of treating glass have been used to manufacture optical fibers having an outer cladding tube. For example, U.S. patent No. 5922099 to Yoon et al and U.S. patent application publication No. 2003/0148053 to Wang et al describe the casting of sol-gel materials into a tubular mold to form an overclad tube of optical fibers and sol-gel rods, comprising a cylindrical core portion and concentric tubular cladding portions around the core portion. U.S. patent No. 6080339 to Fleming et al describes an extrusion process for extruding sol-gel materials to make the outer jacket tube, the substrate tube, and the optical fiber itself. The extruded tube is then subjected to the usual conditions, including the heat treatment for the preparation of the optical fiber. However, none of these documents describe a method of providing a porous monolithic core with intimate liquid contact between the porous monolith and the containment walls, suitable for use in devices used in analytical or preparative processes, and the like. In fact, the methods used to make optical fibers are not suitable for preserving the pores in porous monolithic materials, since the presence of the pores would reduce the optical transparency and transmittance of the fiber, which is therefore a disadvantageous feature for optical fibers.

It is also known to form porous monoliths within capillaries by sol-gel processes. However, fused silica capillaries have very high melting temperatures and, upon their formation and receiving further processing (e.g., drying and firing), the capillary and porous monolith are heated to a temperature high enough to shrink the capillary to maintain contact with the porous monolith, but this will destroy the porosity of the monolith, as is the case for making optical fibers. Therefore, alternative solutions need to be found. For example, U.S. patent No. 6562744 to Nakanishi et al describes a method of making a capillary chromatography column in which the porous material within the capillary tube is said to be in liquid tight contact with the capillary tube because the walls of the capillary tube have an affinity for the gelled silicate component within the porous material. This patent also describes the use of collapsible PTFE capillaries to form a liquid tight contact between the porous material and the capillaries. However, PTFE does not provide sufficient support for the fragile porous monolith formed by the sol-gel process, nor can it be heated to a temperature high enough to calcine the sol-gel monolith to remove organic contaminants. Moreover, according to the teachings of this patent, special treatment of the inner surface of the capillary is required.

A similar method of forming a porous monolith within a fused silica capillary is described in U.S. patent No. 6531060 to Nakanishi et al. U.S. patent application publication No. 2003/0213732 to Malik et al also describes chemically anchoring the monolith to the capillary walls. Further, U.S. patent No. 6783680 to Malik describes a method of forming a sol-gel stationary phase within a fused silica capillary and reports that the sol-gel bonds to the capillary wall by chemical bonding due to condensation reactions with silanol groups on the inner surface of the capillary. The capillary may be heated to 350 ℃ for further processing. However, the above technique is only applicable when the dimensions are small, as in capillaries, the diameter of the capillary is typically less than 1mm, typically less than 0.1 mm. For example, the maximum diameter of the fused silica capillary used by Malik is only 0.25mm, and such a small diameter limits the application and effectiveness of the method.

Another difficulty encountered in minimizing leakage or gaps between the porous monolith and its containment structure, particularly when prepared by sol-gel methods, is that handling operations can cause shrinkage or cracking during the drying step of the manufacturing process. Attempts to reduce cracking have focused on increasing the pore size of the monolith to reduce the stresses that the capillaries develop during drying. For example, U.S. patent No. 5023208 to Pope describes a process for hydrothermal aging of gels, which reportedly promotes the migration of silica particles, filling pores in a porous gel matrix, and increasing the average pore size. According to Wang, U.S. patent No. 6620368, at the end of the first phase of the deliquoring process, the density of the gel is equivalent to about 15% -35% shrinkage of its linear dimension. However, these additional processing steps are time consuming and costly to manufacture.

U.S. patent No. 6210570 to Holloway describes a method of preparing a chromatography column containing a minimally constricting hydrosol, wherein the hydrosol initially has a first volume and, after forming a monolith therewith, has a second volume that is at least about 95% of the first volume. SiO in the hydrosol is described₂Is less than about 5g/ml, or between about 3g/ml and about 5 g/ml. The patent also states that SiO is due to₂Too low a concentration should strike a balance between preventing syneresis and producing a brittle silica product. It is reported that, in the process of the hydrogel gradually becoming a hydrogel, since the degree of "syneresis" or volume shrinkage is reduced as described above, the resolution problem caused by the mobile phase effectively bypassing the portion of the stationary phase, which results in poor separation of components during chromatographic separation, is avoided. However, these methods of producing porous monoliths with reduced shrinkage sacrifice control of gel composition, porosity and pore size distribution, and the resulting porous monoliths lack mechanical strength.

Thus, there remains a need for a shrinkable support material that can be applied to the outer surface of a porous monolith to minimize gaps, create more intimate contact, and reduce leakage.

Disclosure of Invention

Accordingly, it is a primary object of the present invention to meet the above-described need in the art by providing an inorganic shrinkable support that can be applied to the outer surface of porous materials for chromatography, filtration, purification, catalysis, and the like. Methods of making related structures from such materials are also desirable.

Accordingly, the present invention provides an article of manufacture or device (or a component of an article of manufacture or device) comprising a porous inorganic substrate (supported porous substrate) contained within or bounded by a support made of an inorganic material, wherein the porous substrate and support are heated to a temperature effective to shrink the support onto the porous substrate, thereby forming a liquid tight contact between the porous substrate and the support. Thus, the article provides a restricted fluid flow through the porous substrate, which fluid flow cannot bypass the porous substrate, thereby providing superior performance in separation, catalysis, filtration, and the like.

Preferably, the porous inorganic substrate has a total porosity of at least 5%. In some embodiments, the porous substrate is characterized by a total porosity of at least 60%; in other embodiments, the porous substrate is characterized by a total porosity of about 85% to about 97%. In some embodiments, the porous substrate is characterized by a mesopore mode distribution (mesopore mode distribution) of from about 2nm to about 100 nm; in other embodiments, the porous substrate is characterized by a mesopore pattern distribution of about 8nm to about 50nm and a mesopore volume of at least about 0.2cm³Per gram, more preferably at least about 0.5cm³(ii) in terms of/g. In a particularly preferred embodiment, the porous inorganic substrate is a porous monolith comprising an inorganic material and having a total porosity of at least 5% ("supported porous monolith"). In some embodiments, the porous monolith is characterized by a mesopore model distribution of about 2nm to about 100 nm; in other embodiments, the porous monolith is characterized by a mesopore model distribution of about 8nm to about 50nm and a mesopore volume of at least about 0.2cm³Per gram, more preferably at least about 0.5cm³(ii) in terms of/g. However, the porosity and specific pore characteristics of the porous inorganic substrate are not limited and may be selected according to the particular application.

In particular embodiments, the temperature effective to shrink the support onto the porous inorganic substrate is a temperature effective to soften the support (e.g., a softening temperature), causing the support to shrink into liquid tight contact with the porous inorganic substrate. Preferably, the effective temperature at which the support is shrunk onto the porous monolith has no effect on the pore distribution of the porous monolith. In particular embodiments, the effective temperature for shrinking the support onto the porous monolith is less than about 2000 ℃, more preferably less than about 1000 ℃.

In a particular embodiment, a vacuum is applied to the interior of the support (e.g., the unheated end), wherein the application of the vacuum results in a temperature drop as shrinkage occurs. By appropriate selection of the porous inorganic substrate (whether monolithic or non-monolithic, optionally having the desired composition, porosity and/or pore characteristics) and the support (having a particular softening temperature), and performing the shrinking step under suitable conditions (e.g., with or without application of a vacuum to the support), an article or device having the desired porosity and/or pore characteristics and forming a liquid tight contact between the porous substrate and the support can be obtained.

In some embodiments, the porous inorganic substrate is initially spaced from the support by a gap that, when heated to a temperature effective to soften the support, shrinks onto the porous inorganic substrate such that the gap is minimized and the porous substrate is in liquid tight contact with the support. In other embodiments, the porous inorganic substrate is formed in a support without a gap between the support and the substrate (e.g., forming a sol-gel monolith), and then heated to shrink the support while the porous monolith shrinks upon firing or to shrink after the porous monolith is fired such that there are no gaps between them at least when the final processing temperature is reached. In some embodiments, there is no gap between them at any stage in the process. In other embodiments, a sufficient vacuum is applied to the support to reduce the temperature at which shrinkage occurs.

In some preferred embodiments, the porous inorganic substrate and the support have a cylindrical shape. In a specific embodiment, the support has an inner diameter greater than about 1 mm. In other embodiments, the support has an inner diameter of less than about 1 mm. In a particularly preferred embodiment, the article is suitable for use in chromatography, catalysis, adsorption, filtration, fuel cells, optoelectronic devices, sensing technology or hydrogen storage applications, most preferably as a chromatography column in the field of chromatography.

In some aspects, the porous inorganic substrate comprises an inorganic material or an inorganic-organic hybrid material; in particular embodiments, the inorganic material comprises a glass or ceramic material. Preferably, the inorganic material comprises a metal or metalloid oxide, preferably an oxide of Si, Ge, Sn, Al, Ga, Mg, Mb, Co, Ni, Ga, Be, Y, La, Pb, V, Nb, Ti, Zr, Ta, W, Hf, or combinations thereof.

In a preferred aspect, the porous inorganic substrate is a porous monolith formed by a sol-gel process using one or more sol-gel precursors containing hydroxyl or hydrolysable ligands (ligands) capable of undergoing a sol-gel reaction to form a sol-gel. Suitable hydrolyzable ligands include, but are not limited to, halogen, alkoxy, amino, or acyloxy. In particular embodiments, the sol-gel precursor may also include organic substituents, and may include organosilanes, such as alkoxysilanes, halosilanes, acyloxysilanes, or aminosilanes, which may further include organic substituents, such as saturated or unsaturated hydrocarbyl substituents, aryl substituents, or combinations thereof. Typical alkoxysilanes may include, for example, alkyltrialkoxysilanes, cycloalkyltrialkoxysilanes, dialkyldialkoxysilanes, trialkylalkoxysilanes, tetraalkoxysilanes, vinyltrialkoxysilanes, allyltrialkoxysilanes, phenylalkyldialkoxysilanes, diphenylalkoxysilanes or naphthyltrialkoxysilanes, or mixtures thereof. The sol-gel precursor comprising organic substituents may also comprise other organometallic compounds, such as organogermanes, or organically substituted titanium, aluminum, zirconium or vanadium alkoxides, and the like. In another preferred embodiment, the silane is a silane mixture comprising a trialkoxysilane and a tetraalkoxysilane. In an alternative embodiment, the porous monolith is formed from particles that have been modified to form a monolith.

In particular embodiments, the porosity, chemical properties, adsorption properties, or catalytic properties of the porous monolith are modified by, but are not limited to, the introduction of a binding phase (e.g., by reaction with an organosilane or capping agent), the introduction of a catalytic function (e.g., platinum, a protein such as an enzyme, a nucleic acid such as a ribozyme), the reconstruction of the structure (e.g., using a matrix dissolution catalyst or hydrothermal treatment), or the introduction of a sensor (e.g., a dye or enzyme). Alternatively, the porous monolith may be formed with components that provide improved characteristics, i.e., provide catalytic function, bonded phase, structural reconstruction, or sensors, etc.

In a particular embodiment, the support is made of an inorganic material comprising a glass or ceramic material. Preferably, the support is a non-porous material. In a specific embodiment, the support is formed by a sol-gel process.

In some aspects, the article further comprises a polymeric outer layer, which may have a threaded end. Preferably, the polymeric outer layer is a liquid crystal polymer, a thermoplastic polymer resin or a thermosetting polymer resin. In a specific embodiment, the outer polymer coating is Polyaryletheretherketone (PEEK).

In other embodiments, the present disclosure provides a method of forming an article comprising a porous inorganic substrate in liquid tight contact with an inorganic support, the method comprising: 1) assembling a porous inorganic substrate into a shrinkable support comprising an inorganic material; and 2) heating the article to a temperature effective to shrink the support to the porous inorganic substrate, thereby forming a liquid tight contact between the porous substrate and the support.

In some aspects, the porous inorganic substrate comprises an inorganic material or an inorganic-organic hybrid material; in particular embodiments, the inorganic material comprises a glass or ceramic material. Preferably, the inorganic material comprises a metal or metalloid oxide, preferably an oxide of Si, Ge, Sn, Al, Ga, Mg, Mb, Co, Ni, Ga, Be, Y, La, Pb, V, Nb, Ti, Zr, Ta, W, Hf, or combinations thereof.

In a preferred aspect, the porous inorganic substrate is a porous monolith formed using a sol-gel process using one or more sol-gel precursors containing hydroxyl or hydrolysable ligands capable of undergoing a sol-gel reaction to form a sol-gel. Suitable hydrolyzable ligands include, but are not limited to, halogen, alkoxy, amino, or acyloxy. In particular embodiments, the sol-gel precursor may also include organic substituents, and may include organosilanes, such as alkoxysilanes, halosilanes, acyloxysilanes, or aminosilanes, which may further include organic substituents, such as saturated or unsaturated hydrocarbyl substituents, aryl substituents, or combinations thereof. In an alternative embodiment, the porous monolith is formed from particles that have been modified to form a monolith.

Preferably, the article is a chromatographic column comprising an inorganic porous monolithic stationary phase encased in a support of inorganic material, the chromatographic column being fabricated by a process which provides liquid tight contact between the porous inorganic monolith and the support. When used to prepare a chromatography column, the method preferably provides a chromatography column having improved chromatographic efficiency and improved separation effect, peak shape, peak height, etc., and is easy to manufacture and cost-reduced, compared to prior art methods in which no liquid tight contact is formed between the porous inorganic substrate and the support.

In a particular embodiment, the porous monolith is formed separately from the shrinkable support and is inserted into the support prior to shrinking. In other embodiments, the porous monolith is formed in the shrinkable support prior to shrinking the support.

Preferably, the shrinkable support is formed of an inorganic material such as glass or ceramic. In a particular embodiment, the shrinkable support is made by a sol-gel process.

In particular embodiments, the article is suitable for use in chromatography, catalysis, adsorption, separation, filtration, fuel cells, optoelectronic devices, sensing technology, or hydrogen storage applications, most preferably for use in chromatography. In some embodiments, the method further comprises providing an outer protective layer comprising glass, metal, polymer, or a combination thereof. The polymeric outer layer may be applied by any method known in the art, such as coating, shrinking, extruding or overmolding (overmolding) methods. In preferred embodiments, the article is used for chromatography, filtration or purification, catalysis, environmental or medical detection, energy generation in fuel cells, hydrogen storage, or optical switching in optoelectronic devices.

In a particularly preferred embodiment, the present invention provides a chromatography column comprising a porous monolith enclosed within a glass tube, the improvement comprising forming the porous monolith from a sol-gel, assembling the porous monolith into the glass tube, and heating the assembly to fire the sol-gel and shrink the glass tube, thereby forming a liquid tight contact between the porous monolith and the glass tube. In a specific embodiment, the porous monolith is formed and fired inside the glass tube. In some embodiments, the heating is performed in multiple stages to dry the sol-gel and fire the sol-gel to shrink the glass tube. In other embodiments, the heating is performed in a single temperature programmed step.

In another aspect, the present invention provides a method of separating a mixture of analytes in a sample, the method comprising the steps of: 1) providing a chromatographic column comprising a porous monolith enclosed within a glass tube, wherein the chromatographic column is heated to shrink the glass tube, thereby forming a liquid tight contact between the porous monolith and the glass tube; 2) adding the sample to a chromatographic column; 3) eluting the column with a mobile phase; and 4) collecting the separated analytes eluted from the chromatographic column.

Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.

Drawings

FIG. 1 shows an embodiment of the invention in which a porous monolithic rod is inserted into a shrinkable tube and heated to shrink the tube onto the rod.

Figure 2 shows a second embodiment of the invention in which a porous monolith is formed in a shrinkable tube by a sol-gel process, the porous monolith and tube are heated together, the rod is fired, and the tube is shrunk onto the rod.

FIG. 3A shows an embodiment of the invention suitable for use in chromatography, showing a thermoplastic overcoat layer with threaded mounting heads (threaded mounts) at each end.

Figure 3B shows a cross-sectional view of the chromatography column of figure 3A showing the outer thermoplastic outer coating, shrinkable tube and inner porous monolith.

FIG. 4 shows a chromatogram demonstrating the superior performance of the embodiment of example 1 for separating analytes.

Detailed Description

I. Definitions and overview

Before describing the present invention in detail, it is to be understood that unless otherwise indicated, the present invention is not limited to specific inorganic substrates, sol-gel formulations, glasses, porous media, surface treatments, chromatographic methods, filtration and purification structures, catalytic structures, and the like, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

It must be noted that, as used herein and in the claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a metal oxide" includes two or more metal oxides; "a support" includes two or more supports, and so on.

Where a range of values is provided, it is understood that each intervening value, to the extent there is no such stated, or any other stated or intervening value in the stated range, is encompassed within the invention; unless otherwise expressly stated, the intervening values are to the tenth of the unit of the lower limit. The upper and lower limits of these sub-ranges may independently be included in the sub-ranges, and are also encompassed within the invention, unless any limit within the scope is specifically excluded. Where the stated range includes one or both of the two limits, ranges excluding either or both of those limits are also included in the invention.

The term "porosity" as used herein refers to the proportion of volume in the porous inorganic substrate that is in an open state, i.e., not occupied by solid material, and may include the proportion of volume occupied by gas (e.g., nitrogen or air or a gaseous mobile phase) or liquid (e.g., a liquid mobile phase). Typically, the porosity is at least 5%, but any porosity may be selected to suit a particular application.

The term "macroporous" as used herein means a diameter greater than about 0.05 μm (50nm or 500 nm)) The aperture of (a); the term "mesoporous" means having a diameter of between about 2nm and 50nm (20 nm)-500) The aperture of (a); the term "microporous" refers to a diameter of less than about 2.0nm (20)) The hole of (2).

As used herein, the term "total pore volume" refers to the total volume of pores in the monolith, typically expressed in cm³In terms of/g or cc/g. The total pore volume can be determined by mercury intrusion, i.e. pumping Hg at high pressure into the pores.

The term "BET surface area" refers to the surface area as determined by the BET method, which can be determined using single or multiple point analysis. Example (b)For example, the method can be implemented in Micromeritics TriStar 3000 instruments (Norcross, GA), Nocrols, Georgia, USA]Multiple nitrogen adsorption measurements were performed. Then, the specific surface area can be calculated by the multipoint BET method, and the model pore size (mode pore diameter) is calculated from the logarithmic differential pore volume distribution [ dV/dlog (D) -D]The resulting most frequent diameter (the most frequent diameter). Mesopore volume of P/P₀The total pore volume of the single points was calculated at 0.98.

The term "monolith" refers to a porous three-dimensional material having a continuous interconnected pore structure in a single piece, rather than a collection of discrete particles packed into a volume.

As used herein, the term "liquid tight contact" refers to a condition in which the support shrinks to the extent that it contacts the porous inorganic substrate, such that fluid flow through the porous inorganic substrate is restricted by the support and fluid does not substantially flow between the porous inorganic substrate and the support. Liquid tight contact also includes gas tight contact. Liquid-tight contact may also include chemical bonding (e.g., silanol condensation) between the support and the substrate, which may be formed when the porous substrate is in intimate contact with the support. For example, when used in chromatography, liquid-tight contact is evidenced by separation of analytes and the appearance of symmetrical peak shapes. If the mobile phase leaks between the porous inorganic substrate and the support, poor or no separation of the analytes and poor peak shape results. Thus, the superior separation and the peaked shape obtained in example 4 indicate that liquid tight contact can be achieved using the method of the present invention.

The present invention relates to unique articles and methods of forming them, such as chromatography columns, filters, catalytic structures, optical devices (e.g., waveguides), fuel cells, hydrogen storage devices, and the like, wherein a liquid tight contact is formed between a porous inorganic substrate and a porous inorganic support structure. The present inventors have surprisingly found that shrinkable inorganic materials, when heated, can shrink or shrink into liquid tight contact with the outer surface of the porous substrate to achieve superior properties and performance. Although these materials have been widely used by those skilled in the art for the preparation of chromatography columns and similar devices, to the inventors' knowledge to date, the inventors were the first to discover that inorganic supports can shrink under heat to form a liquid tight contact with the outer surface of a porous substrate, such as a porous glass monolith, and can take advantage of this property to produce products with superior performance, ease of use, and manufacture.

Accordingly, the present invention provides a supported porous substrate comprising a porous inorganic substrate bounded or bounded by a support made of an inorganic material, wherein the porous substrate and support are heated to a temperature effective to shrink the support onto the porous substrate, thereby forming a liquid tight contact between the porous monolith and the support. Thus, the article provides a restricted fluid flow through the porous substrate, which fluid flow cannot bypass the porous substrate, thus providing superior performance in separation, catalysis, filtration, and the like. Preferably, the porous inorganic substrate is a porous monolith, thereby providing a supported porous monolith.

The method is particularly suitable for high porosity structures, substrates that are fragile or sensitive to the environmental conditions of use, applications using corrosive solvents or gases, applications operating at high temperatures, indeed any application where glass or ceramic materials are preferred, not allowing edge leakage to occur. The apparatus and methods described herein are particularly useful in applications where it is desirable to restrict fluid flow through a porous bed, particularly a monolithic bed, because the intimate contact between the porous substrate and the support structure prevents fluid flow therebetween, i.e., there is liquid tight contact therebetween.

Such structures may have any size or shape to suit the needs of any particular application. For example, for chromatographic applications, the structure may be in the form of a capillary tube having a small diameter (e.g., an inner diameter of 10 μm to 1mm), which is particularly suitable for analytical applications, while for chromatographic preparative applications, the structure may be larger, such as a tube having a larger diameter (e.g., an inner diameter greater than 1mm, up to 6 inches or more). Theoretically, there is no limitation on the size, and the size of the device can be determined completely according to the limitations of practical applications. For some applications, much larger diameter tubes may be used, as well as non-tubular structures. Smaller structures may also be designed for microfabricated devices. The invention can be used to manufacture parts in any relevant size range, requiring only sufficient material and processing equipment of sufficient size to handle the part to be processed.

The materials for the porous substrate and the shrinkable support may be selected from suitable commercial or custom sources. For example, inorganic porous substrates may include inorganic chromatography media, filtration media, fuel cell compositions, sensors and sensor arrays, optoelectronic devices, hydrogen storage media or catalytic support media, optionally with any suitable surface treatment to facilitate a particular analytical measurement, chemical process, adsorption process, optical property, or the like. The porous inorganic substrates can be used as controlled porosity media for liquid or gas flow, for mechanical filtration of particles of specific size, as large surface area reaction or adsorption surfaces, for purification, catalytic reactions, energy generation, and the like.

Similarly, the shrinkable support can be made of any suitable material that is capable of shrinking or shrinking upon heating without damaging the porous inorganic substrate. For example, any glass or ceramic material or metal is suitable, provided that they sufficiently soften and shrink at acceptable processing temperatures. In a particular embodiment, glass or ceramic tubes made by sol-gel casting or extrusion are used. In addition, the support itself may be porous if it is useful for a particular application. In a preferred embodiment, the glass or ceramic tube may be a conventional extruded or drawn product.

Generally, two basic methods are available for assembling the porous substrate into liquid tight contact with the support substrate. Referring to fig. 1A, in one embodiment, a porous inorganic substrate, i.e., a porous monolith 10, is first prepared using a suitable method. It can then be inserted into the opening of the shrinkable support 11. The assembly is heated to shrink the support 11 and bring it into liquid tight contact with the porous monolith 10, resulting in a shaped article 12 having liquid tight contact between the support and the porous monolith.

Referring to fig. 1B, in another embodiment, the porous inorganic substrate is prepared in situ by filling the containing support 22 with a suitable precursor material 20. In a preferred embodiment, the precursor material is a sol-gel held in the support by means of a seal 24, which may be dried in situ or accelerated by heating, or both. If the porous inorganic substrate has not been previously dried, the assembly can be heated to further convert the porous inorganic substrate to monolithic xerogel 21. If desired, the porous monolith may be further fired by heating to a firing temperature. The heating also causes the support to shrink to its final configuration 23, forming a liquid tight contact with the porous monolith. The temperature range and time over which the desired changes occur can be readily adjusted to complete drying and shrinkage of the porous monolith before the support substrate shrinks to its final dimensions.

In particular embodiments, the porous substrate may be a non-monolithic porous solid. For example, the porous substrate 10 may be formed from compacted porous particles. The support may be contracted as shown in fig. 1A to make liquid tight contact with the support 11.

The basic process shown in FIG. 1B can also be used for non-monolithic porous media. The support 22 may be filled with particles such as powders or beads which are further modified by surface reaction or sintering to agglomerate or agglomerate the particles and thereby render the porous particulate substrate a monolithic substrate. Combinations of the above steps may also be employed.

In any of the embodiments described above, a vacuum may be applied to the interior of the support to cause the support to shrink onto the porous inorganic substrate at a temperature lower than that required in the absence of the vacuum. For example, applying a vacuum of about 20 inches of mercury may reduce the softening temperature required for shrinkage by about 100-. One skilled in the art will readily appreciate from this disclosure that the appropriate softening temperature for the support and the appropriate firing or sintering temperature for the porous monolith can be selected with or without the application of vacuum.

In any of the above embodiments, the surface modification may be performed before or after the shrinkage of the support, if appropriate. For example, a bonding phase may be incorporated into the porous inorganic substrate, or the porous inorganic substrate may be subjected to a capping treatment to reduce residual silanols. Generally, to avoid heating, the introduction of any organic moieties is performed after the shrinking step is completed. Surface preparation and introduction of polar bonding phases may also be performed at this stage, for example, as described in U.S. patent No. 7125488 to Li.

In addition, additional optional outer protective layers or coatings (e.g., glass, metal, or polymer layers) may be applied by coating, casting, overmolding, or other methods in order to provide protection and/or facilitate assembly of the final article into a device. Preferably, the polymeric outer layer is a liquid crystal polymer, a thermoplastic polymer resin or a thermosetting polymer resin. In a specific embodiment, the outer polymer coating is Polyaryletheretherketone (PEEK). The polymeric outer coating may be used to provide the article with a suitable configuration, such as a threaded end, a fluid adapter (flow adapter), or the like, to facilitate assembly of the article into equipment for any desired application.

As shown in fig. 2, a thermoplastic resin layer having a threaded end 30 may be overmolded onto a supporting porous substrate to form a chromatography column 31. The cross-sectional view shows that the shrinkable glass or ceramic tube comprises a porous monolith located within an outer thermoplastic resin layer. In other embodiments, the plastic or rubber coating may be applied by dip coating, spray coating, or heat shrinking methods. Similarly, other materials may be assembled onto the final support substrate by wrapping around the article or inserting or other methods.

FIG. 3 shows a photograph of an actual column formed using the liquid crystal polymer dope as shown in FIG. 2. In FIG. 3B, the cross-section shown is obtained by cutting across the column shown in FIG. 3A. The cross-section shows that the porous monolith is in liquid tight contact with the support without a gap between the porous monolith and the support, resulting in a chromatography column suitable for chromatographic separations.

Various aspects and embodiments of the invention are set forth in greater detail below.

Support body

The support can have any shape and size suitable for the intended use, so long as it provides support to and/or contains the porous inorganic substrate and softens at a suitable temperature. The support shape may be generally flat or curved, tubular or cylindrical, square or diamond, etc., without limitation. The support may be in the form of a wall surrounding and containing the porous inorganic substrate, or may be in the form of a block lacking identifiable wall structures, so long as the support is in liquid tight contact with the porous inorganic substrate when heated to the softening temperature.

By "encasing" the porous inorganic substrate, it is meant that the support provides support and control for the substrate such that the porous inorganic substrate is in contact with or in an operative positional relationship with the associated device. The substrate may be fragile and/or may need to be maintained under controlled environmental conditions, such as exposure or non-exposure to air or certain gases or liquids, while the support may contain the substrate to provide the mechanical, chemical, electrical, etc. environment desired for a particular application. The porous inorganic substrate is supported by the support when the support provides a suitable means for inserting the porous substrate into a housing or another device without damaging the surface or exposing the porous substrate to adverse environmental conditions, or making the porous substrate part of, for example, an apparatus.

In some embodiments, the porous inorganic substrate is cylindrical and the support is tubular, the support accommodating the porous substrate along its axis but remaining open or partially open at either end. However, the porous substrate may be contained in the support at both ends, or only partially contained in the support, e.g., the support covers a portion of the porous substrate rather than the entire surface. In other embodiments, the porous substrate may be substantially planar or two-dimensional, and the support may contain the substrate on only one side or both sides or only on the edges, without limitation. Indeed, those skilled in the art will readily envision many possible arrangements and geometries of the porous substrate and support for the applications described herein.

In a preferred embodiment, the support may be in the form of a tube for receiving the porous monolith. In one embodiment, the support may be formed from a sol-gel monolith by any method known in the art. For example, a tubular support may be formed using the method described in U.S. patent No. 5922099 to Yoon, wherein a sol-gel tube is formed and dried from the outside to reduce the formation of cracks; forming a tubular support using a sol-gel extrusion process as shown in Fleming, U.S. patent No. 6080339; and so on.

In another preferred embodiment, the support is in the form of a tube formed from glass, such as a low-melting borosilicate glass, and the porous inorganic substrate is a porous monolith, wherein after assembly of the porous monolith into the glass tube, the assembly is heated to the softening point of the glass tube, and the glass tube softens or melts, forming an assembly with liquid-tight contact between the porous monolith and the glass tube.

In another embodiment, additional supports may be included as desired. For example, the porous inorganic substrate can be assembled into a glass tube and then the entire assembly placed into a second, larger glass tube. An outer protective layer (e.g., metal or polymer) may also be included as desired for protection or assembly into the final device or apparatus. Additional processing steps (e.g., heating to anneal, temper, or shrink) may also be taken to further modify the additional layers to provide the desired configuration and form the desired contact with the supporting substrate.

One skilled in the art can readily envision suitable supports and support compositions having the desired melting or softening temperature, thickness, shape, mechanical and/or electrical properties, resistance to acids/bases/solvents, and the like. Typical supports include silica-based glasses, which may be pure (e.g., quartz) or may be doped with a suitable dopant to provide the desired propertiesThe quality of (2). For example, fused silica, such as that used to prepare optical glass, fiber optics, and the like, melts at high temperatures of about 1800-2000 ℃, softens at 1580 ℃, and can shrink at temperatures as low as about 1700 ℃. The presence of the non-silica component can degrade the thermal properties of the glass. For example, borosilicate glass softens at lower temperatures of about 750-. Table 1 lists some representative glasses and the approximate temperatures at which they soften. For some glasses, the data listed are approximate values, and to determine a more accurate softening temperature, relevant specifications can be obtained from the manufacturer, since the presence of different amounts of additives in the glass can alter its properties. For example,the softening temperature of (A) is 825 DEG CThe softening temperature of (2) is 821 ℃.

Table 1 physical properties of representative glasses

Other glasses are also representative of the scope of the invention, but the invention is not limited to any particular glass. For example, AF45[ Scott North America, Elmseford, N.Y. (Schott North America, Inc., Elmsford, NY)]Is a catalyst having a high proportion of BaO and Al₂O₃Alkali-free borosilicate glass of (1). D263T is borosilicate glass manufactured using high purity raw materials.Is a trademark of 96% silica glass sold by Corning Specialty Materials, Corning, NY, usa for high temperature applications. General ratio of softening temperature of glassT of it_g(glass transition temperature) is about 200 ℃.

Low temperature melting glasses include, for example, those described in U.S. Pat. No. 4323654 to TiCk, which describes alkali-Ta₂O₅-B₂O₃-P₂O₅Glass for use in a molded optical device having a high refractive index and a glass transition temperature of less than 500 ℃. Another example is shown in U.S. Pat. No. 3926649 to Ray, which describes alkali borophosphate glasses in which P is present₂O₅∶B₂O₃In a ratio of from 15: 1 to 6: 1, with only minor proportions of minor components such as SiO₂And Al₂O₃Preferably at least one alkali metal oxide such as Li₂O、Na₂O and K₂O, together with at least one alkaline earth metal oxide or zinc oxide, such as MgO, CaO and BaO. These glasses are reported to have glass transition temperatures below 225 ℃ and different water solubilities at 100 ℃.

One skilled in the art can readily determine glasses having desired characteristics, such as low or high water solubility, low or high melting or softening temperatures, and the like. For certain applications, glasses with high water solubility may be acceptable because only non-aqueous solvents are used, or no solvents at all are used (e.g., gaseous applications), or final dissolution of the glass support is a desirable feature.

Porous inorganic substrate

The porous inorganic substrate may comprise any porous ceramic, glass, metal, etc., so long as the porous inorganic substrate is stable under the conditions that enclose the porous inorganic substrate within the shrinkable support. By porous inorganic substrate being stable to the conditions used it is meant that it is chemically and mechanically resistant to the temperatures and pressures involved in the relevant processes, i.e. it does not deform, evaporate or melt.

The porous inorganic substrate is preferably monolithic, rather than being composed of microparticles. Preferably, the porous inorganic substrate has a total porosity of at least 5%. In some embodiments, the porous substrateCharacterized in that it has a total porosity of at least 60%; in other embodiments, the porous substrate is characterized by a total porosity of about 85% to about 97%. In a particularly preferred embodiment, the porous inorganic substrate is a porous monolith comprising inorganic material and having a total porosity of at least 5%. In some embodiments, the porous monolith is characterized by a pore model distribution therein of from about 2nm to about 50 nm; in other embodiments, the porous monolith is characterized by a pore pattern distribution of from about 20nm to about 50nm and a mesopore volume of at least about 0.2cm³Per gram, more preferably at least about 1.0cm³(ii) in terms of/g. However, the porosity and specific pore characteristics of the porous inorganic substrate are not limited and may be selected to suit a particular application.

The monolith may comprise any monolithic material suitable for high temperatures and may be made of ceramic and glass or metal, etc. In addition, the porous monolith can be prepared using any method known in the art. For example, in some embodiments, the porous monolith may comprise a metal such as silver, copper, titanium, or cobalt, among others, and may be prepared using a method for producing nanoporous metal foams, as described in U.S. patent No. 7141675 to Tappan. In a preferred embodiment, the porous monolithic material is a glass or ceramic prepared by a sol-gel process.

A. Sol-gel monolith

Sol-gel precursors include metal and metalloid compounds having hydrolyzable ligands that can undergo a sol-gel reaction to form a sol-gel. Suitable hydrolyzable groups include, without limitation, hydroxyl, alkoxy, halogen, amino, or amide groups. The most common metal oxide that participates in the sol-gel reaction is silica, but other metals and metalloids may also be employed, such as zirconia, vanadia, titania, niobia, tantalum oxide, tungsten oxide, tin oxide, hafnium oxide, and alumina or mixtures or composites thereof, with reactive metal oxides, halides, amines, etc., capable of reacting to form a sol-gel. Other metal atoms that may be incorporated into the sol-gel precursor include, without limitation, magnesium, molybdenum, cobalt, nickel, gallium, beryllium, yttrium, lanthanum, tin, lead, and boron.

Preferred metal oxides and alkoxides (alkoxides) include, but are not limited to, silicon alkoxides such as Tetramethylorthosilicate (TMOS), Tetraethylorthosilicate (TEOS), fluoroalkoxysilane, or chloroalkoxysilane; germanium alkoxides [ such as tetraethyl-n-germane (TEOG) ], vanadium alkoxides, aluminum alkoxides, zirconium alkoxides, and titanium alkoxides. Similarly, metal halide, amine and acyloxy derivatives may also be used in sol-gel reactions.

In a preferred embodiment, the sol-gel precursor is an alkoxide of silicon, germanium, aluminum, titanium, zirconium, vanadium or hafnium, or a mixture thereof. In a particularly preferred embodiment, the sol-gel precursor is a silane. In a more preferred embodiment, the sol-gel precursor is a silane such as TEOS or TMOS.

In particular embodiments, the sol-gel precursor may further comprise organic substituents. Accordingly, sol-gel monoliths formed from sol-gel precursors containing organic substituents comprise monoliths of inorganic-organic mixtures. Sol-gel precursors containing organic substituents include, but are not limited to: organosilanes having a saturated or unsaturated hydrocarbyl substituent, such as alkyltrialkoxysilanes, cycloalkyltrialkoxysilanes, dialkyldialkoxysilanes, trialkylalkoxysilanes, tetraalkoxysilanes, vinyltrialkoxysilanes, allyltrialkoxysilanes; or organosilanes with aryl substituents, such as phenylalkyldialkoxysilanes, diphenylalkoxysilanes or naphthyltrialkoxysilanes; or mixtures thereof. The organic substituent-containing sol-gel precursor may also include other organometallic compounds such as organogermanes or organically substituted titanium alkoxides, aluminum alkoxides, zirconium alkoxides, vanadium alkoxides, or the like. A suitable hydrocarbyl substituent may be C_1-100More generally C_1-30. In another preferred embodiment, the silane is a silane mixture comprising a trialkoxysilane and a tetraalkoxysilane. Furthermore, the sol-gel monolith may be surface modified with organic substituents, such as alkyl silane containing bonding phases or capping agents. In thatIn these embodiments, the sol-gel monolith must be treated at a temperature that does not destroy the desired organic functional groups, or the organic substituents must be added after heating at a temperature that will destroy the organic substituents.

In other embodiments, the porous monolith may be prepared from particles that have been modified and agglomerated or sintered to form a monolith. For example, U.S. patent application publication No. 2003/0150811 to Walter describes a method of forming a porous inorganic/organic hybrid material, which reportedly includes the steps of: the porous inorganic/organic hybrid particles are first formed, the pore structure of the porous hybrid particles is modified, the porous hybrid particles are then agglomerated to form a monolith, and the monolith is optionally further subjected to a hydrothermal treatment in order to modify the pore structure. In this embodiment, the porous monolith may be an inorganic or inorganic-organic hybrid material, depending on the particulate composition used.

In some embodiments, the porous monolith may be prepared by a sol-gel process, as described in U.S. patent nos. 5009688, 5624875, and 6207098 to Nakanishi, 5100841 to Wada, 6398962 to Cabrera, and the like. For example, as reported in Nakanishi, U.S. Pat. No. 5009688, during the hydrolysis and polymerization of metal alkoxides or oligomers thereof, the dissolved organic polymer undergoes phase separation, resulting in a porous product. The porous gel is heated and calcined to convert it to SiO with improved mechanical strength₂And (3) porous ceramics. It is also beneficial to employ a particle structure formed from a sol-gel that can form a hierarchically ordered porous oxide (as described in U.S. patent No. 6541539 to Yang et al) or a mesoporous ordered material (as described in U.S. patent No. 6592764 to Stucky et al), as described herein.

Other methods of forming porous monoliths include the methods described in U.S. patent nos. 6884822, 7026362, and 7125912 to Wang. According to the teachings of these patents, HF can be used to promote the formation of larger pore sizes, thereby reducing the likelihood of gel monolith rupture. However, the inventors have shown that the use of a catalyst such as HF also reduces the gelling time, resulting in insufficient time for treatment or diffusion of bubbles out of the gel, thereby reducing the quality of the resulting gel. The inventors describe a process for making a xerogel monolith which comprises preparing a first solution comprising a metal alkoxide, a second solution comprising a catalyst, mixing said first and second solutions together, wherein at least one of the two solutions is cooled so that the temperature of the mixture of the third solution is substantially below room temperature. Thus, the reported mixtures have significantly longer gel times at the mixing temperature than at room temperature.

In a preferred embodiment, the sol-gel monolith is prepared by a process described in co-pending U.S. patent publication No. 2006/0131238, which produces a porous monolith having a high porosity characterized by the presence of mesopores and macropores and the absence of micropores.

B. Pore-forming agent

When preparing porous monoliths by the sol-gel process, pore formers (porogens) may be used as auxiliaries. For example, U.S. patent No. 5009688 to Nakanishi reports the use of dissolved organic polymers such as polystyrene sulfonic acid, polyacrylic acid, polyallylamine, polyethyleneimine, polyethylene oxide, or polyvinylpyrrolidone to create pores during the hydrolysis and polymerization of sol-gel precursors. When sol-gel monoliths are prepared in the presence of phase separation volumes, sol-gel monoliths with large and/or large mesopores are obtained, so that the sol-gel monoliths have a greater porosity and the solvent also has a superior flow rate.

In one embodiment, the porogen may be a hydrophilic polymer. The amount and hydrophilicity of the hydrophilic polymer in the sol-gel forming solution has an effect on the pore volume and pore size of the formed macropores, and there is generally no particular requirement for the molecular weight range, but a molecular weight between about 1000 and about 1000000g/mol is preferred. The pore former may be selected from, for example, polyethylene glycol (PEG), sodium polystyrene sulfonate, polyacrylates, polyallylamine, polyethyleneimine, polyethylene oxide, polyvinylpyrrolidone, polyacrylic acid, polymers that may also include amino acids, polysaccharides such as cellulose ethers, or esters such as cellulose acetate, and the like. Preferably, the polymer is PEG having a molecular weight of up to about 1000000 g/mol.

The porogen may also be an amide solvent such as a polyamide, or an amide polymer such as polyacrylamide, or a surfactant such as a nonionic surfactant, an ionic surfactant, an amphiphilic surfactant, or mixtures thereof. A preferred surfactant is the nonionic surfactant pluronic f68 (also known as Poloxamer).

Exemplary surfactants include surfactants having HLB values between about 10-25, such as polyethylene glycol 400 monostearate, polyoxyethylene-4-sorbitan monolaurate, polyoxyethylene-20-sorbitan monooleate, polyoxyethylene-20-sorbitan monopalmitate, polyoxyethylene-20-sorbitan monolaurate, polyoxyethylene-40-stearate, sodium oleate, and the like.

Some embodiments preferably employ nonionic surfactants including, for example, polyoxyethylene stearates such as polyoxyethylene 40 stearate, polyoxyethylene 50 stearate, polyoxyethylene 100 stearate, polyoxyethylene 12 distearate, polyoxyethylene 32 distearate, and polyoxyethylene 150 distearate, as well as other Myrj^TMA series of surfactants, or mixtures thereof. Another class of surfactants useful as porogens is ethylene oxide/propylene oxide/ethylene oxide triblock copolymers, also known as poloxamers, having the general formula HO (C)₂H₄O)_a(-C₃H₆O)_b(C₂H₄O)_aH, available under the trade names Pluronic and Poloxamer. Other useful surfactants include sugar ester surfactants; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate; other Span^TMA series of surfactants; glycerol fatty acid esters such as glycerol monostearate; polyoxyethylene derivatives, such as polyoxyethylene ethers of high molecular weight fatty alcohols (e.g. Brij 30, 35, 58, 78 and 99), polyoxyethylene stearates (self-emulsifying), polyoxyethylene 40 sorbitol lanolin derivatives, polyoxyethylene 75 sorbitol lanolin derivatives, polyoxyethylene 6 sorbitol beeswax derivatives, polyoxyethylene 20 sorbitol lanolin derivatives, polyoxyethylene 50 sorbitol lanolin derivatives, polyoxyethylene 23 lauryl ether, polyoxyethylene 2 cetyl ether containing butylated hydroxyanisole, polyoxyethylene 10 cetyl ether, polyoxyethylene 20 cetyl ether, polyoxyethylene 2 stearyl ether, polyoxyethylene 10 stearyl ether, polyoxyethylene 20 stearyl ether, polyoxyethylene 21 stearyl ether, polyoxyethylene 20 oleyl ether, polyoxyethylene 40 stearate, polyoxyethylene 50 stearate, Polyoxyethylene 100 stearate; polyoxyethylene derivatives of fatty acid esters of sorbitan, such as polyoxyethylene 4 sorbitan monostearate, polyoxyethylene 20 sorbitan tristearate; other Tween^TMA series of surfactants; phospholipids and phospholipid fatty acid derivatives, such as lecithin; an aliphatic amine oxide; fatty acid alkanolamides; propylene glycol monoesters and monoglycerides, such as hydrogenated palm oil monoglyceride, hydrogenated soybean oil monoglyceride, hydrogenated palm oil stearin monoglyceride (hydrogenated palm stearine monoglyceride), hydrogenated vegetable oil monoglyceride, hydrogenated cottonseed oil monoglyceride, refined palm oil monoglyceride, partially hydrogenated soybean oil monoglyceride, cottonseed oil monoglyceride, sunflower oil monoglyceride, canola oil monoglyceride (canola oil monoglyceride), succinylated monoglycerides, acetylated monoglycerides, acetylated hydrogenated vegetable oil monoglycerides, acetylated hydrogenated coconut oil monoglycerides, acetylated hydrogenated soybean oil monoglycerides, glycerol monostearate, hydrogenated soybean oil monoglyceride, hydrogenated palm oil monoglyceride, succinylated monoglycerides and monoglycerides, monoglycerides and rapeseed oil, monoglycerides and cottonseed oil, monoglycerides with sodium stearoyl lactylate silica propylene glycol monoester (monogyceride without propylene glycol).colmonooester sodium stearoyl lactylate silicon dioxide); a diglyceride; a triglyceride; polyoxyethylene type solid alcohol ethers; Triton-X series surfactants produced by the polymerization of octylphenol with ethylene oxide, where the number "100" in the trade name is indirectly related to the number of ethylene oxide units in the structure (e.g., Triton X-100)^TMHaving an average of 9.5 ethylene oxide units per molecule and an average molecular weight of 625), low molar and high molar adducts present in small amounts in the commercial product and having a functionality similar to that of Triton X-100^TMCompounds of structure comprising Igepalca-630^TMAnd Nonidet P-40M [ NP-40^TMN-lauroylsarcosine, St.Louis, Mo., St.chemical Co., St.Louis, St.]And the like. Any hydrocarbon chain in the surfactant molecule may be saturated or unsaturated, hydrogenated or unhydrogenated.

A particularly preferred class of surfactants are poloxamer surfactants, which are a: b: a triblock copolymers of ethylene oxide to propylene oxide to ethylene oxide. "a" and "b" represent the average number of monomer units per block in the polymer chain. These surfactants are available from BASF Corporation of Mount Olive, new jersey, usa, and have various molecular weights and different numbers of "a" and "b" blocks. For example,f127 has a molecular weight of 9840-; the molecular weight of LutrolF87 is 6840-8830, wherein "a" is 64 and "b" is 37; the average molecular weight of Lutrol F108 is 12700-17400, wherein "a" is 141 and "b" is 44; lutrol F68 has an average molecular weight of 7680-9510, wherein "a" is about 80 and "b" is about 27.

Sugar ester surfactants include sugar fatty acid monoesters, sugar fatty acid diesters, triesters, tetraesters, or mixtures thereof, although monoesters and diesters are most preferred. Preferably, the glycolipid fatty acid monoesterContaining C6-24 fatty acid, which may be linear or branched, or saturated or unsaturated C₆-C₂₄A fatty acid. Preferably, C₆-C₂₄The fatty acid is selected from stearic acid, behenic acid, coconut oil acid, arachidonic acid, palmitic acid, myristic acid, lauric acid, capric acid esters (carprate), oleic acid, lauric acid, and mixtures thereof, and may contain even or odd numbers of carbon atoms in any subrange or combination. Preferably, the sugar fatty acid monoester comprises at least one saccharide unit, such as sucrose, maltose, glucose, fructose, mannose, galactose, arabinose, xylose, lactose, sorbitol, trehalose or methylglucose. Disaccharide esters such as sucrose esters are most preferred and include sucrose cocoate, sucrose monocaprylate, sucrose monodecanoate, sucrose monolaurate or dilaurate, sucrose monolaurate, sucrose monopalmitate or dipalmitate, sucrose monostearate or distearate, sucrose monooleate, dioleate or trioleate, sucrose monolinoleate or dilinoleate, sucrose polyesters such as sucrose pentaoleate, hexaoleate, heptaoleate or octaoleate, and mixed esters such as sucrose palmitate/stearate.

Particularly preferred examples of such sugar ester surfactants include those sold by Croda Inc (of Parsippany, NJ), of pasippanni, new jersey, under the trade designations Crodesta F10, F50, F160, and F110, which represent various mono-ester, di-ester, and mono/di-ester mixtures comprising sucrose stearate, produced using a process that controls the degree of esterification, as described in U.S. patent No. 3480616.

Sugar ester surfactants sold by Mitsubishi under the trade name Ryoto sugar ester, e.g., B370, corresponding to sucrose behenate consisting of 20% monoester and 80% diester, triester and polyester may also be used. Sucrose monopalmitate and dipalmitate/stearate sold by Goldschmidt, Inc. (Goldschmidt) under the trade name "TegosoftPSE" may also be used. Mixtures of these different products may also be used. Sugar esters may also be used in admixture with another compound not derived from sugar; a preferred example comprises a mixture of sorbitan stearate and sucrose cocoate sold under the trade name "Arlatone 2121" by ICI. Other sugar esters include, for example, glucose trioleate, galactose di-, tri-, tetra-or pentaoleate, arabinose di-, tri-or tetralinoleate, or xylose di-, tri-or tetralinoleate, or mixtures thereof. Other fatty acid sugar esters include methyl glucose esters, including distearate of methyl glucose and distearate of polyglycerol-3 sold under the trade name Tegocare 450 by the company gord smith. It is also possible to add glucose or maltose monoesters, such as methyl O-hexadecanoyl-6-D-glucoside and O-hexadecanoyl-6-D-maltose. Other sugar ester surfactants include the oxyethylated esters of fatty acids and sugars, including the oxyethylated derivatives such as PEG-20 methyl glucose sesquistearate sold under the trade name "Glucamate SSE 20" by Amerchol.

One of the characteristics of surfactants is the HLB value, i.e., the hydrophilic lipophilic balance value. This value represents the relative hydrophilicity and relative hydrophobicity of the surfactant molecules. In general, the higher the HLB value, the more hydrophilic the surfactant; the lower the HLB value, the more hydrophobic. For example, forThe molecule, the ethylene oxide moiety represents the hydrophilic moiety and the propylene oxide moiety represents the hydrophobic moiety. The HLB values for lutrol F127, F87, F108, and F68 were 22.0, 24.0, 27.0, and 29.0, respectively. Preferred sugar ester surfactants have HLB values between about 3 and about 15.

Characterization of the pore Structure of the porous inorganic substrate

The pore size distribution curve can be obtained by deriving (dV/dlogD) the pore volume (V) from the pore size (D) and then plotting the variation with the pore size (D). The model pore size is the pore size at which the dV/dlogD value in the pore size distribution curve is maximum (shown as the maximum peak). This pore size distribution curve is derived from the adsorption isotherm obtained by measuring nitrogen adsorption, for example, according to several equations. Adsorption isotherm measurements generally include the following steps: the sample was cooled to liquid nitrogen temperature, nitrogen gas was introduced, and the amount of adsorbed nitrogen was determined by fixed displacement method (fixed displacement) or gravimetric method. The pressure of the introduced nitrogen gas is gradually increased, and the nitrogen gas adsorption amount when pressure equilibrium is reached each time is plotted to obtain an adsorption isotherm. The pore size distribution curve can be obtained from the adsorption isotherms according to the equations of the Cranston-Inklay method (Cranston-Inklay), the Dollimore-Hill method (Dollimore-Heal), the BET method, the BJH method, and the like.

The total surface area and micropore volume can be conveniently determined using an instrument such as Micromeritics TriStar 300, as described herein. The total surface area is preferably calculated using the BET method and the micropore pore volume is calculated using the t-curve method, as described by Mikal, R.et al (1968) J.colloid Interface Sci.26, 45. the t-curve method can be used to detect the presence of micropores in a sample and determine their pore volume. the t-curve is a graph plotting the nitrogen adsorption amount (v/g) against the average film thickness (t) of the adsorption film (where the x-axis is the average film thickness and the y-axis is the adsorption amount). If no micropores or mesopores are present, the nitrogen adsorption quantity is linear with the layer thickness. Otherwise, the presence of micropores can be detected by nitrogen adsorption loss at a particular thickness, and the diameter of the pores that do not provide available surface area can be calculated.

V. method for preparing supported porous inorganic substrates

In other embodiments, methods of forming a supported porous substrate are provided, comprising: 1) assembling a porous inorganic substrate into a shrinkable support comprising an inorganic material to obtain an assembly; 2) the assembly is heated to a temperature effective to shrink the support onto the porous substrate, thereby shrinking the support onto the porous substrate to form a liquid tight contact between the porous inorganic substrate and the support.

Preferably, the porous substrate is a porous monolith comprising an inorganic material such as glass, ceramic or metal. In some preferred embodiments, the porous monolith is a porous glass monolith made by a sol-gel process. In other embodiments, the porous monolith is formed from particles, but the particles are modified to form the monolith.

In a specific embodiment, the porous substrate or porous monolith is formed separately from the shrinkable support shown and then inserted into the support before the support is shrunk. In other embodiments, the porous inorganic substrate or porous monolith is formed within a shrinkable support as shown, and the support is then shrunk. The porous inorganic substrate may be introduced by stacking, coating, impregnating, cladding, wrapping, or other techniques known in the art, depending on the requirements of the particular device.

Preferably, the shrinkable support is formed of an inorganic material such as glass or ceramic. In a particular embodiment, the shrinkable support is made by a sol-gel process.

In particular embodiments, the temperature effective to shrink the support onto the porous inorganic substrate is a temperature (e.g., softening temperature) effective to soften the support such that the support shrinks into liquid-tight contact with the porous inorganic substrate. Preferably, the temperature at which the support is effectively shrunk onto the porous monolith has no or only a limited effect on the pore distribution of the porous monolith. In particular embodiments, the temperature effective to shrink the support onto the porous monolith is less than about 2000 ℃, more preferably less than about 1000 ℃.

In some embodiments, the porous inorganic substrate and the support are initially separated by a gap, for example, when the porous substrate is formed separately and then inserted into a tubular support; followed by heating to a temperature effective to soften the support, the support shrinks onto the porous inorganic substrate to minimize the gap and form a liquid tight contact between the porous substrate and the support. In addition, a porous substrate may be formed in the support that, when dried and/or fired, separates out of contact with the support substrate. Heating is then applied to shrink the support onto the porous substrate so that the gap is minimized and liquid tight contact is established between the two. Alternatively, when the porous substrate is formed in the support, there is no gap therebetween, and then heating is performed to cause shrinkage of the support and the porous substrate at the same time as firing, or shrinkage after firing of the porous substrate, so that there is no gap therebetween at least after completion of the heat treatment. In some embodiments, there is no gap between them at any stage of the process. In a preferred embodiment, the substrate is a porous monolith, more preferably a porous glass monolith. In other embodiments, a sufficient vacuum is applied to the support to reduce the temperature at which shrinkage occurs.

In a particular embodiment, a vacuum is applied to the interior of the support, e.g., to one end of the tube (e.g., the unheated end), wherein the application of the vacuum results in a temperature drop as shrinkage occurs. By appropriate selection of the porous inorganic substrate (monolithic or non-monolithic substrate, optionally having a desired composition, porosity and/or pore characteristics) and the support (having a particular softening temperature), and performing the shrinking step under suitable conditions (e.g., with or without application of a vacuum to the support), an article or device can be obtained having the desired porosity and/or pore characteristics and forming a liquid tight contact between the porous substrate and the support.

The lower range of temperatures at which the support is effectively shrunk into liquid tight contact with the porous substrate is not particularly limited and may be selected according to the desired characteristics of the porous substrate and controlled by the degree of vacuum applied and the softening temperature of the support. The effective temperature is at least 100 c, more preferably between about 200 c and 2000 c. In particular embodiments, the effective temperature is between about 100 ℃ and 400 ℃. In other embodiments, the effective temperature is between about 200 ℃ and 900 ℃. In other embodiments, the effective temperature is between about 400 ℃ and 1000 ℃. In other embodiments, the effective temperature is between about 300 ℃ and 700 ℃.

For example, for a porous monolith having a desired pore size distribution and surface area in the structure, a lower softening temperature glass may be used and the shrinking step may be performed at a lower temperature (e.g., 200℃.) to preserve the microporous structure. For porous substrates having the desired mesopore distribution, glasses with higher softening temperatures can be used because the mesopore distribution is less susceptible to high temperatures than the micropore distribution. If the pore characteristics of the porous substrate are not particularly limited, the softening temperature of the support is not particularly limited and higher or lower softening temperatures may be employed as desired for a particular application.

In the following examples, the temperature used for shrinkage is 850 ℃, which is an acceptable shrinkage temperature for the borosilicate glass support used and the high porosity sol-gel monolith prepared. However, for these embodiments, the effective temperature range may be from about 400 ℃ to about 1000 ℃.

Applications and methods of use

The articles and devices described herein have a wide range of end-use applications in the separation and catalytic science fields, such as materials in chromatography columns, filtration membranes [ e.g., reverse osmosis, ultrafiltration, preparative filtration, etc. ], microtiter plates, scavenger resins (scavenger resins), solid phase organic synthesis supports, fuel cells, sensor arrays, photovoltaic devices, hydrogen storage devices, and the like. In a preferred embodiment, the articles and devices find application in the field of chromatography, where liquid tight contact is made between a support and a porous inorganic substrate, which serves as the stationary phase, such chromatographic devices having improved elution profiles due to reduced peak broadening and increased chromatographic efficiency. In another embodiment, where the articles and devices are used in the catalytic field, the porous substrate may further comprise a catalytic functional component such as an enzyme or a metal, and the like. In a particularly advantageous embodiment, the article is a chromatography device, for example a chromatography column, such as a chromatography column commonly used in HPLC.

Applications in the fields of TLC and microfluidics do not generally require a shrinkable support, since the porous monolith does not shrink enough to cause separation and undesired leakage when it comes into contact with the support. However, in the event that significant shrinkage of the porous monolith occurs or fluid leakage between the porous monolith and the support would lead to unacceptable results, the use of a shrinkable support can restore liquid-tight contact, which is desirable for optimal function. For example, if the sol-gel formed within the microfluidic channel is removed from contact with the microfluidic support substrate, the use of a collapsible support enables fluid tight contact to be restored, which is required for optimal functioning of the microfluidic device.

Thus, in one embodiment, the present invention provides a chromatography column for performing liquid chromatography (including HPLC) comprising a porous monolith encased in a glass support, which may be further adapted for liquid chromatography by the addition of necessary end fittings, tubing, and the like.

In another embodiment, the invention provides a capillary chromatography column comprising a stationary phase of a porous monolith contained within a capillary tube, wherein the capillary tube and the porous monolith are shrunk together, for example by calcining.

In another aspect, the present invention provides a method of separating a mixture of analytes in a sample, the method comprising the steps of: 1) providing a chromatographic device, particularly a chromatographic column, comprising a porous inorganic substrate enclosed within a glass tube, wherein the chromatographic column is heated to shrink the glass tube, thereby forming a liquid tight contact between the porous inorganic substrate and the glass tube; 2) adding the sample to a chromatographic column; 3) eluting the column with a mobile phase; and 4) collecting the analytes eluted from the chromatographic column. Preferably, the porous substrate is a porous monolith. Suitable separations can be carried out using the following methods: thin layer chromatography, high performance liquid chromatography, reverse phase chromatography, normal phase chromatography, ion pair chromatography, reverse phase ion pair chromatography, ion exchange chromatography, affinity chromatography, hydrophobic interaction chromatography, size exclusion chromatography, chiral recognition chromatography, perfusion chromatography, electrochromatography, partition chromatography, microcolumn liquid chromatography, Capillary Zone Electrophoresis (CZE), nano-LC, Open Tube Liquid Chromatography (OTLC), Capillary Electrochromatography (CEC), liquid-solid chromatography, preparative chromatography, hydrophilic interaction chromatography, supercritical fluid chromatography, precipitation liquid chromatography, bonded phase chromatography, flash liquid chromatography, flash chromatography, liquid chromatography-mass spectrometry, gas chromatography, microfluidic based separation, chip based separation, or solid phase extraction separation.

The articles and methods of the invention may be advantageously used in chromatographic and analytical separation applications in the form of chromatographic columns or other devices having improved flow properties, reduced back pressure, controlled pore size distribution, and possibly reduced silanol residue, eliminating peak tailing for basic analytes. For example, the porous monolith can be introduced into a capillary column, a cartridge system (cartridge system), or a conventional HPLC system, among others. Since the substrates described herein are substantially rigid, e.g., monolithic adsorbents, which can leave dead corners during coating, it can be challenging to coat the substrate or monolith in a pressure-stable manner to form columns, filters, cartridges, or the like without leaving dead corners. In one embodiment, a substrate or sol-gel monolith may be used to prepare the cartridge, for example, as described in U.S. patent No. 6797174, which describes a coated column containing a monolithic adsorbent and a coupling system comprising at least one separate support screw and at least one end piece threaded onto the support screw for coupling the entry and exit of eluent. Alternatively, the substrate or porous monolith can be introduced into the cartridge system without the use of a cap. The use of a shrinkable support as described herein and shrinking the support onto a porous substrate by heating provides an improved system.

In a particularly advantageous embodiment, the chromatographic apparatus is a chromatographic column, such as an HPLC column. Figure 3B shows a cross-sectional micrograph of a porous sol-gel monolith in a glass tube. The tube had an initial internal diameter of 1.8mm and a diameter of 1.2mm after shrinking onto the fired porous monolith. The porous monolith structure can be seen with no gaps in fluid tight contact between the monolith and the tube. It is advantageous to use such a chromatographic apparatus for HPLC separation, the chromatographic performance of which is improved.

Supported porous monoliths can also be used in the form of planar supports for planar applications (e.g., TLC, etc.), or as components in devices such as microfluidic devices, and other devices that may have planar geometries, such as filtration devices and membranes, solid phase extraction media, microtiter plates, fuel cells, photovoltaic devices. Any shape may be formed without limitation, such as rods, spheres, hollow or packed structures (e.g., hollow tubes), flat sheets, fibers, chips, micro-wires or nano-wires or other shapes suitable for chromatographic, adsorptive, catalytic, or other applications. The supported porous substrate may also be treated to modify its pore structure or surface chemistry. For example, polymeric, organic or inorganic phases and/or layers may be incorporated and/or coated onto the surface of the porous substrate to mobilize specific adsorption or catalytic properties.

The supported porous substrates may also be used in other applications such as filtration, solid phase synthesis, bioreactors, catalysis, resins, sensing devices, medical devices and pharmaceuticals, or other active agent delivery platforms, fuel cells, optoelectronic devices, and the like. The method can also be used to prepare devices for carrying out these applications. The supported porous substrate may comprise inorganic as well as organic or biological components. The supported porous monolith can be used as a stationary phase comprising a superporous inorganic/organic and/or biological hybrid material. The stationary phase may be introduced by in situ polymerization or the support may be inserted and shrunk onto the porous monolith as described herein, depending on the requirements of the particular device. In a preferred embodiment, the porous monolith is formed in situ in such a device. In another preferred embodiment, the porous sol-gel monolith is formed in a mold, then transferred to a support, and the support is shrunk onto the porous monolith, optionally at a site ready for use.

In particular embodiments, the porous sol-gel monoliths of the present invention can be used in methods for making devices for capillary and microfluidic applications, which typically employ smaller column internal diameters (< 100 μm) and lower mobile phase flow rates (< 300 nL/min). Such as capillary chromatography, Capillary Zone Electrophoresis (CZE), nano-LC, open-tube liquid chromatography (OTLC) and Capillary Electrochromatography (CEC) have numerous advantages over conventional High Performance Liquid Chromatography (HPLC). These advantages include higher separation efficiency, high speed separation, small sample volume for analysis, and a combination of two-dimensional techniques. However, even these applications, which benefit from the nanoporous sol-gel monolith described herein, make it possible to obtain higher flow rates and more uniform, more easily controlled pore size distributions.

For rapid analysis of samples, microchip-based separation devices have been developed. Examples of microchip-based separation devices include devices for capillary electrophoresis, capillary electrochromatography, and high performance liquid chromatography. For example, a chromatography chip can be made by introducing a sol-gel monolith into a chromatography chip, e.g., by forming grooves in a plate and then forming a monolithic silica gel having a bimodal pore structure in the grooves. Representative chromatography chips and methods of making and using the same are described in U.S. patent application publication No. 2003/0230524 to Naohiro. Compared with other conventional analytical instruments, the above and other separation devices can perform rapid analysis, improving accuracy and reliability. These chip-based separation devices and other separation devices have higher sample throughput, reduced sample and reagent usage, and reduced chemical waste compared to other conventional separation devices. For most applications, the liquid flow rate in the microchip-based separation device is in the range of about 1 to 300 nl/min. The superporous sol-gel monoliths described herein can be incorporated into these microfluidic designs to provide monolithic adsorbents in the microchannels of chip-based separation devices, thereby providing faster flow rates for microchip applications.

Advantages of the invention

Some of the advantages and features of the articles and methods of the present invention include:

glass or ceramic tubes treated by shrinkage as described herein have a smoother inner surface than equivalent metal or plastic tubes. Smooth interior surfaces produce excellent results in applications such as chromatography, where a smoother surface reduces edge effects and allows the mobile phase to flow more uniformly through the substrate bed [ rather than between the substrate bed and containment wall ]. As a result, the chromatography columns prepared by the methods described herein have higher chromatographic efficiency, improved peak shape, and reduced diffusion broadening.

In addition, the apparatus and methods of the present invention provide for a liquid tight contact between the porous inorganic substrate and the support. When used for preparing chromatographic column, the method improves chromatographic efficiency, promotes separation, and improves peak shape, peak height, etc. In addition, the apparatus and method provide excellent flow rates, reducing the number of separations. Similarly, the devices and methods can provide excellent catalytic efficiency because the devices have excellent flow properties.

The apparatus and method can withstand high processing and operating temperatures and provide excellent solvent resistance.

The present invention provides a good support for a potentially fragile high porosity monolithic medium such as a nanoporous sol-gel monolith as described in co-pending U.S. patent publication No. 2006/0131238.

The support is sufficient for the manufacture of an outer plastic structure.

Shrinkage of the support to achieve the target size and compensate for any shrinkage in the porous substrate is easily controlled. The method is easily adapted to be used with a wide variety of components having dimensions that vary over a wide range.

No surface modification of the inner surface of the glass support is required, nor is an additional gelling step required to attach the porous monolith to the glass support. Thus, the entire manufacturing process is simple, cost-effective and reproducible.

In the following examples, efforts have been made to ensure accuracy with respect to numbers used (e.g., amounts, temperature, etc.) but some experimental errors and deviations should be accounted for. Unless otherwise indicated, the temperature is in degrees Celsius and the pressure is at or near atmospheric. All solvents purchased were HPLC grade and all reactions were routinely conducted in air unless otherwise indicated.

Example 1

Preparation of liquid-tight contacting porous monoliths and supports

The nonionic surfactant Pluronic F68(0.44g, Basff) was dissolved in a mixture of 1.1g water, 3.6g methanol, 2.1g reagent alcohol (reagent alcohol) and 0.96g HF (2.6M). 5.0ml of Tetraethoxysilane (TEOS) was added to the above solution with stirring to form a homogeneous mixture. After 5 minutes, the sol was injected into a polymer tube with an Inner Diameter (ID) of 1.6 mm. After 30 minutes, the sol turned into a white gel, which was then aged, dried and transferred to an oven and calcined at a temperature of about 550 ℃ overnight. The gel was removed from the tube prior to firing.

The final outer diameter of the porous monolith was about 1.2 mm. BET surface area, mesopore pore volume and model diameter were measured using Micromeritics TriStar 3000: BET surface area of about 400m²(ii) a mesopore volume of 1.1cm³A median pore diameter of about 100The total pore volume was estimated to be about 5.0cm as measured by mercury intrusion³/g。

The silica monolith thus formed was then inserted into a silicate glass tube (corning corporation, corning, n.y., usa) having an inner diameter of 1.8mm, and the glass tube was heat-treated in an oven at a temperature of 850 c until the glass sealed the surface of the gel column.

After the surface of the gel column was completely sealed, the glass tube and porous monolith were cut into 100mm long pieces suitable for use as chromatography columns. The post is overmolded with a Liquid Crystal Polymer (LCP) with threads formed on both ends for mounting the fitting. Excess glass is then cut and polished to give the desired column length of 50 mm.

The resulting column is shown in FIG. 3A. The cross-section of the column (as shown in fig. 3B) shows no separation between the porous monolith and the glass tube; if separated, will affect the chromatographic performance of the column. The chromatographic properties were tested as described in example 4.

Example 2

Preparation of liquid-tight contacting porous monoliths and supports

A mixture was prepared as in example 1: the nonionic surfactant Pluronic F68(0.44g, Basff) was dissolved in a mixture of 1.1g water, 3.6g methanol, 2.1g reagent alcohol and 0.96g HF (2.6M). 5.0ml TEOS was added to the above solution with stirring to form a homogeneous mixture.

After 5 minutes, the sol was injected into a glass tube having an inner diameter of 2.4 mm. After 30 minutes, the sol turned into a white gel, which was then aged, dried and fired at a temperature of about 550 ℃. The silica monolith inside the tube shrank from 2.4mm to about 2.0mm, at which point it was loose inside the tube.

The gel and glass tube were then heat treated at a temperature of 850 ℃. After the surface of the gel column was completely sealed, the glass column was cut into 100mm long columns, over-molded with liquid crystal polymer as described in example 1, and threaded at both ends for fitting. Excess glass is then cut and polished to give the desired column length of 50 mm.

Example 3

Preparation of liquid-tight contacting porous monoliths and supports

The procedure of example 1 was repeated except that: only one end of the borosilicate glass tube with the porous monolith inside was melted and the end was sealed. After the glass has cooled, a vacuum (about 20 inches of mercury) is applied from the open end of the glass tube to heat the glass tube containing the porous monolith to a temperature at which the glass tube softens and shrinks under the influence of the external atmospheric pressure to form a seal with the silica monolith inside. The use of vacuum allows the shrinking to occur at a lower temperature than without vacuum, and the temperature range suitable for the shrinking step becomes wider.

Example 4

Chromatographic performance of liquid tight contacting porous monolith and support

The chromatographic performance of the column prepared in example 1 was tested to determine if this procedure resulted in liquid tight contact between the porous monolith and the support. The column size was 1.2mm (internal diameter) x5mm long, the mobile phase consisted of 99% hexane and 1% isopropanol, the flow rate was 50 μ l/min, and detection was performed using UV absorption at 254 nm. The analytes were toluene, diethyl phthalate, dimethyl phthalate. The results are shown in FIG. 4.

As shown in fig. 4, the analytes were separated and showed symmetrical peaks, indicating that the mobile phase was confined to flow through the monolith bed of the column, so that a liquid tight contact was established between the porous monolith and the glass tube. If there is no liquid tight contact between the porous monolith and the glass tube, no or incomplete separation will be observed.

Claims (24)

1. An article comprising a porous inorganic substrate encased in a support made of an inorganic material, wherein the porous substrate and the support are heated to a temperature effective to shrink the support onto the porous substrate, forming a liquid tight contact between the porous substrate and the support.

2. The article of claim 1, wherein the porous inorganic substrate is a porous monolith.

3. The article of claim 1, wherein sufficient vacuum is applied to the support to reduce the temperature at which shrinkage occurs.

4. The article of claim 1, wherein the article is suitable for use in chromatography, catalysis, adsorption, filtration, fuel cells, optoelectronic devices, sensor technology, or hydrogen storage.

5. The article according to claim 1, wherein the porous inorganic substrate comprises an inorganic material or an inorganic-organic hybrid material.

6. The article of claim 5, wherein the inorganic material comprises a metal oxide or a metalloid oxide.

7. The article of claim 1, wherein the inorganic porous substrate is a porous monolith formed using a sol-gel process.

8. The article of claim 1, wherein the porosity, chemical properties, adsorptivity or catalytic properties of the porous substrate are improved.

9. The article of claim 13, wherein the improvement is selected from the group consisting of: incorporation of binding phases, incorporation of catalytic functions, structural reconstruction or incorporation of sensors.

10. The article of claim 1, wherein the inorganic material from which the support is made comprises a glass or ceramic material.

11. The article of claim 1, further comprising a protective outer layer.

12. A method of forming an article comprising a porous inorganic substrate in liquid tight contact with an inorganic support, the method comprising:

1) assembling a porous inorganic substrate into a shrinkable support comprising an inorganic material; and

2) the article is heated to a temperature effective to shrink the support onto the porous substrate, thereby shrinking the support onto the porous substrate, thereby forming a liquid tight contact between the porous inorganic substrate and the support.

13. The method of claim 12, wherein the porous inorganic substrate comprises a metal oxide or metalloid oxide selected from oxides of Si, Ge, Sn, Al, Ga, Mg, Mb, Co, Ni, Ga, Be, Y, La, Pb, V, Nb, Ti, Zr, Ta, W, Hf, or combinations thereof.

14. The method of claim 12, wherein the porous inorganic substrate is a monolith.

15. The method of claim 14, wherein the porous inorganic substrate is formed using a sol-gel process.

16. The method of claim 14, wherein the porous monolith is formed from particles that have been modified to form a monolith.

17. A method according to claim 14, wherein the porous monolith and the shrinkable support are formed separately and the monolith is then inserted into the support prior to shrinking the support.

18. The method of claim 14, wherein the porous monolith is formed within the support prior to shrinking the support.

19. The method of claim 12, wherein the shrinkable support is glass or ceramic.

20. A method according to claim 12, wherein sufficient vacuum is applied to the support to reduce the temperature at which shrinkage occurs.

21. The article of claim 1, wherein the liquid tight contact between the porous inorganic substrate and the support is formed by a method comprising:

1) assembling a porous inorganic substrate into a shrinkable support comprising an inorganic material;

2) the article is heated to a temperature effective to shrink the support onto the porous substrate.

22. In a chromatographic column comprising a porous inorganic monolith enclosed within a glass tube, the improvement comprising: forming a porous inorganic monolith from the sol-gel, firing the porous inorganic monolith, assembling it into a glass tube, and heating the assembled assembly to shrink the glass tube, thereby forming a liquid tight contact between the porous inorganic monolith and the glass tube.

23. The chromatography column of claim 22, wherein the porous inorganic monolith is formed and fired in a glass tube and the assembly is then heated to shrink the glass tube.

24. A method of separating a mixture of analytes in a sample, the method comprising the steps of:

1) providing a chromatographic column comprising a porous inorganic substrate enclosed within a glass tube, wherein the chromatographic column is heated to shrink the glass tube, thereby forming a liquid tight contact between the porous inorganic substrate and the glass tube;

2) adding the sample to a chromatographic column;

3) eluting the column with a mobile phase; and

4) the analytes eluted from the column are collected.