TWI645897B - Method for producing three-dimensional ordered porous microstructure and monolithic column produced thereby - Google Patents

Abstract

The present invention relates to a method of fabricating a three-dimensional ordered porous microstructure. The invention relates to the process of forming a three-dimensional ordered microstructure by using a colloidal crystal stencil method, and after the particles are self-assembled, deforming the particles in the formed three-dimensional ordered microstructure to effectively enhance the ordered arrangement. The contact between the particles even removes the solvent used to suspend the particles. The invention also relates to a monolithic column made by the three-dimensional ordered porous microstructure fabrication method. Compared with the monolithic column produced by the conventional method, the monolithic column of the present invention has the structural characteristics of high aspect ratio and high hole regularity, and the communication hole in the column also has a relatively large aperture.

Description

Method for manufacturing three-dimensional ordered porous microstructure and integral column made by the same method

The present invention relates to a method of fabricating a three-dimensional ordered porous microstructure. The present invention also relates to a three-dimensional ordered porous microstructure having a high thickness produced by the manufacturing method, particularly a monolithic column having a high aspect ratio.

If the pores in the porous material have a pore diameter close to the wavelength of light and have a high order of arrangement, the porous material may have special and highly practical optical properties, and can be widely applied to photocatalysis, biological carriers, adsorption, filtration, Insulation, chromatographic separation, semiconductors and micro-sensing.

The basic structure of an ordered porous microstructure consists of a medium having a periodic arrangement in one, two, or three dimensions, wherein the one-dimensional structure is a so-called optical multilayer film, which is widely used on optical lenses. The one-dimensional photonic energy gap is caused by the periodic arrangement of the multilayer dielectric film, so that photons in certain wavelength bands cannot pass through, achieving high-efficiency reflection. It has the two-dimensional and three-dimensional periodic arrangement structure, which is the most important ordered porous microstructure at present.

It is known that three-dimensional ordered porous microstructures can be fabricated in a self-assembly mode, mainly using particles of uniform particle size polystyrene, polymethyl methacrylate or cerium oxide, using natural gravity sedimentation, centrifugation, vacuum The particles are self-assembled on a substrate to form a three-dimensional ordered microstructure, and the substrate having a three-dimensional ordered microstructure on the surface thereof is used as a template, and an inorganic oxyalkyl monomer is added to the template to perform sol. The gel reacts to form an inverse structure, and finally the stencil is removed by means of calcination and extraction to form a three-dimensional ordered porous microstructure having photonic crystal properties. The process is generally referred to as colloidal crystal templating, and is disclosed, for example, in U.S. Patent No. 6,144,043 and the Patent Publication No. 104976925A1.

The Republic of China Patent No. I558866 discloses a method for fabricating a three-dimensional ordered microstructure involving applying a shaped electric field to drive the particles into a self-assembly process to form a hexagonal closest packed particle structure. The method disclosed in Patent Cooperation Publication No. WO2017080496A1 involves self-assembly of particles, forming a three-dimensional ordered microstructure on the substrate, and constructing a sacrificial layer between the three-dimensional ordered microstructure and the substrate, so that three-dimensional The ordered porous microstructure maintains structural integrity when detached from the substrate.

Although large-area three-dimensional ordered porous microstructures have been successfully fabricated using the above techniques, the thickness of the microstructures is still unsatisfactory. In the process of constructing a three-dimensional ordered microstructure, at least some of the particles are arranged in the closest packed form, wherein each particle is tangent to the adjacent 12 particles. When the particles are hard spheres, their contact with an adjacent particle is theoretically only one point. Moreover, since the particles used are not completely uniform in particle size, some adjacent particles are not even in contact at all. As the thickness of the three-dimensional ordered microstructure increases, the lack of contact area between the particles tends to result in low structural strength. In particular, a heating process is usually performed to remove the solvent before using the three-dimensional ordered microstructure as the stencil to make the inverse structure. In this heating process, the solvent which is rapidly volatilized after being heated is likely to damage the stencil which is already weak, causing cracks in the stencil, resulting in a low yield of the anti-structure.

Theoretically, a three-dimensional ordered porous microstructure with a high aspect ratio is well suited as a monolithic column for the layer of matter based on its regular internal skeletal network and periodic pore structure. Separation. However, the current process not only takes several days, it is difficult to achieve the scale of mass production, and the finished template structure generally has a loose particle arrangement, resulting in a poor continuity of the subsequently completed three-dimensional ordered porous microstructure product. The aspect ratio is also limited. In addition, in today's colloidal crystal stencil process, hard spheres are used. Since the contact area between adjacent particles in the stencil is small, the interconnected pores between the large pores in the fabricated reverse structure will be too small, resulting in a monolithic column. There is a problem that the mass transfer rate is low and the back pressure is too high. The use of a colloidal crystal stencil to make a monolithic column also requires a time-consuming and inefficient template removal process. These problems severely reduce the manufacturing yield of the monolithic column and its commercial application potential.

Therefore, there is still a strong demand in the industry for the fabrication of three-dimensional ordered micro-structures of high-thickness three-dimensional ordered microstructures and using them as templates.

Now, the inventors of the present invention have unexpectedly discovered that in the process of producing a three-dimensional ordered microstructure by using a colloidal crystal stencil method, after the particles are self-assembled, the particles can be deformed, for example, heating and pressurizing the particles. And dissolve to deform it. The process of deforming the particles not only can effectively improve the contact between the ordered particles, but also can remove the solvent used for the suspended particles by the three-dimensional ordered microstructure, and the solvent which is rapidly volatilized after being heated does not substantially destroy the three-dimensional. Ordered microstructure. More importantly, the three-dimensional ordered microstructure is used as a monolithic column made of a stencil, and the communication hole in the column has a relatively large aperture compared with the communication hole formed by the conventional method, and has high mass transfer efficiency. And the advantage of low back pressure of the column. Accordingly, the present invention solves the above problems in the prior art.

According to a first aspect of the present invention, there is provided a method of fabricating a three-dimensional ordered porous microstructure, characterized in that the method comprises the steps of: A. forming a three-dimensional ordered microstructure composed of a plurality of substantially spherical particles Having a plurality of voids between the plurality of particles; B. deforming the substantially spherical particles in the three-dimensional ordered microstructure such that the particles are deformed to have a longest radius R and a shortest radius r Where r/R ratio is greater than /2 but less than 1; C. filling the void structure into the void; and D. removing the three-dimensional ordered microstructure to obtain the three-dimensional ordered porous microstructure.

In a preferred embodiment, step B comprises heating the three-dimensional ordered microstructure to soften the plurality of particles to undergo deformation. In a more preferred embodiment, the particles have a glass transition temperature, and the step B, in comparison to a high temperature of the glass transition temperature of about 0 to 20 ^o C, and The Three-dimensional ordered microstructure heating. In another more preferred specific embodiment, the particles have a glass transition temperature, and the step B, is compared to a low temperature of the glass transition temperature of about 1 to 15 ^o C will The three-dimensional ordered microstructure is heated. In a more preferred embodiment, in the step of heating, the three-dimensional ordered microstructure is heated at a temperature that is about 3 to 15 ^o C lower than the glass transition temperature. In a more preferred embodiment, the three dimensional ordered microstructure is heated at a temperature that is about 3 to 10 ^o C lower than the glass transition temperature.

In another preferred embodiment, step B includes applying pressure to the three-dimensional ordered microstructure to cause the plurality of particles to deform against one another.

In another preferred embodiment, step B comprises immersing the three-dimensional ordered microstructure in a solvent capable of dissolving the plurality of particles, causing the plurality of particles to swell and deform

In a preferred embodiment, the particles are homogeneous spheres made from a single type of polymeric homopolymer or copolymer, and the glass transition temperature is the overall glass transition temperature of the particles. In another preferred embodiment, the particles have a core-shell structure, each particle has a core and a shell encased outside the core, and the core and the shell are respectively made of different polymer materials, and The glass transition temperature is the glass transition temperature of the outer casing.

In a preferred embodiment, the step of forming a three-dimensional ordered microstructure comprises dispersing the plurality of particles in a solvent to form a suspension, and allowing the plurality of particles to self-assemble to form the Three-dimensional ordered microstructure.

In a preferred embodiment, in the step of heating, the three-dimensional ordered microstructures are heated for a period of time to soften the plurality of particles and remove the solvent.

According to the above technical feature, at least a part of the particles in the three-dimensional ordered microstructure are arranged in the most closely packed form.

In a preferred embodiment, the step of removing the three-dimensional ordered microstructure includes removing the three-dimensional shape by using a method selected from the group consisting of Soxhlet extraction and supercritical fluid extraction. Ordered microstructure.

The above-described three-dimensional ordered porous microstructure manufacturing method is suitable for fabricating a three-dimensional ordered porous microstructure having a high thickness, and is particularly suitable for producing a monolithic column having a high aspect ratio. Moreover, the integral column of the present application has a high aspect ratio, a high hole regularity, and a structural feature of a large aperture of the communicating hole compared to a monolithic column produced by a conventional process.

Therefore, according to a second aspect of the present invention, there is provided a monolithic column which is produced by the above-described method of manufacturing a three-dimensional ordered porous microstructure.

According to the third party of the present invention, it also provides a monolithic column comprising: a plurality of ordered spherical macropores having a uniform diameter of between 100 nm and 6 microns, and a plurality of communicating holes connecting the macropores Having a uniform diameter of between 10 nanometers and 3 micrometers, wherein at least 70% of the macropores are arranged in a densely packed form, and the macropores have a longest radius R and a shortest radius r, wherein The ratio of r/R is less than or equal to 0.99.

In a preferred embodiment, at least 80% of the macropores are arranged in the closest packed form. In a more preferred embodiment, at least 90% of the macropores are arranged in the closest packed form. In a most preferred embodiment, at least 95% of the macropores are arranged in the closest packed form.

In a preferred embodiment, the ratio of r/R is less than or equal to 0.98. In a more preferred embodiment, the ratio of r/R is less than or equal to 0.96. In a most preferred embodiment, the ratio of r/R is less than or equal to 0.94.

In a preferred embodiment, the monolithic column has a height of at least 1 cm and has an aspect ratio of no less than one.

The objects, features, and advantages of the present invention will be described in detail by the embodiments and the accompanying drawings.

Unless otherwise stated, the following terms used in the specification and claims of the present application have the definitions given below. It is to be understood that the singular <RTI ID=0.0>&quot;&quot;&quot;&quot;&quot; A single item. In addition, the open-ended conjunctions such as "including" and "having" used in the claims are intended to mean a combination of elements or components recited in the claims, and do not exclude other components or components not claimed. It should also be noted that the term "or" generally also includes "and/or" in the sense unless the content clearly indicates otherwise. The terms "about" or "substantially" used in the specification and claims of the present application are intended to modify any minor variations, but such minor variations do not alter the nature.

The invention mainly provides a method for manufacturing a three-dimensional ordered porous microstructure, which is suitable for fabricating a three-dimensional ordered porous microstructure having a high thickness, and is particularly suitable for producing a monolithic column having a high aspect ratio. As shown in FIG. 1, the method for fabricating the three-dimensional ordered porous microstructure comprises: A. forming a three-dimensional ordered microstructure composed of a plurality of substantially spherical particles such that the plurality of particles exist between each other. a void; B. deforming the substantially spherical particles in the three-dimensional ordered microstructure such that the particles are deformed to have a longest radius R and a shortest radius r, wherein the ratio of r/R is greater than /2 but less than 1; C. filling the void structure into the void; and D. removing the three-dimensional ordered microstructure to obtain the three-dimensional ordered porous microstructure.

The three-dimensional ordered microstructure refers to a microstructure obtained by three-dimensionally ordering particles. The term "ordered" means that the distance between particles appears to be regular, and it is preferred that the distance between the particles is substantially equal. The particles constituting such a microstructure generally have a uniform particle size, shape, chemical composition, internal structure or surface properties to facilitate non-covalent interaction between the particles, thereby spontaneously arranging into a regular structure similar to a lattice. In a preferred embodiment, the particles are monodisperse substantially spherical particles of uniform particle size, more preferably having a particle size between 1 nanometer and 1000 microns, such as between 100 nanometers and 6 microns.

At least a part of the particles in the three-dimensional ordered microstructure are arranged in the most closely packed form, that is, adjacent particles are tangent to each other, and the center of any three two-two tangent particles constitutes an equilateral triangle. Each particle has a coordination number of 12, and the particles leave a plurality of approximately triangular gaps between the particles. More preferably, at least a part of the particles in the three-dimensional ordered microstructure are in the form of a hexagonal closest packing (hcp), a face centered cubic packing (fcc) or a combination thereof. arrangement. The inverse structure produced by using the above three-dimensional ordered microstructure as a template is the three-dimensional ordered porous structure.

The three-dimensional ordered microstructure can be formed by self-assembly of particles. As used in this specification, the term "self-assembly" refers to the aggregation of micro- or nano-scale particles into a three-dimensional ordered microstructure in response to conditions in the external environment, in particular the van der force between these particles. Non-covalent interactions such as Waals ' force), π-π interaction, hydrogen bonding, etc., thereby spontaneously forming the three-dimensional ordered microstructure under near thermodynamic equilibrium conditions.

Non-limiting examples of materials for making these particles include polymeric materials, inorganic materials, metals, and the like. The polymer material is preferably a thermoplastic polymer material, and examples of the polymer material include, but are not limited to, polymer homopolymers such as polystyrene (PS), polymethyl methacrylate (PMMA), and polybutyl methacrylate ( PBMA), polymethyl acrylate, polyethyl acrylate (PEA), polybutyl acrylate (PBA), polymethyl methacrylate, poly alpha-methyl styrene, polyphenyl methacrylate, polymethyl Diphenyl acrylate and polycycloalkyl methacrylate; and high molecular copolymers such as styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer, styrene-butyl methacrylate copolymer And a styrene-butyl acrylate copolymer. Examples of inorganic materials include, but are not limited to, titanium oxide, zinc oxide, cerium oxide, tin oxide, cerium oxide, cerium oxide, aluminum oxide, cerium oxide, zirconium oxide, copper oxide, nickel oxide, cerium oxide. Examples of metallic materials include, but are not limited to, gold, silver, copper, platinum, aluminum, zinc, lanthanum, cerium, lanthanum, cerium, zirconium, tin, titanium, cadmium, and iron, and alloys thereof.

In a preferred embodiment, the particles used are made of a polymeric material, more preferably the particles used are selected from the group consisting of styrene monomers, methacrylate monomers and acrylates. A homopolymer or a copolymer obtained by polymerizing a monomer. In a specific embodiment, the particles used are homogeneous spheres made from a single type of polymeric homopolymer or copolymer. In another specific embodiment, the particles used have a core-shell architecture. As used herein, "core-shell structure" means that each particle has a core and a shell that is coated outside the core, and the core and the shell are respectively made of different polymer materials. The above-described method for producing micro or nano-sized particles belongs to the prior art. For example, when the particles used are polystyrene particles, they can be synthesized by an emulsion polymerization method without an emulsifier to form polystyrene spherical particles having a particle diameter of several hundred nanometers. When it is desired to form particles having a core-shell structure, an emulsion polymerization method without an emulsifier can be similarly employed, in which the first monomer is first subjected to polymerization for a period of time to form a core, and then the second monomer is added to form a first An outer shell of a copolymer of a second monomer.

In the step A of forming a three-dimensional ordered microstructure, a suspension may be first prepared containing a plurality of uniformly dispersed colloidal spherical particles. For example, when the particles used are polystyrene homopolymer or copolymer particles, the particles can be uniformly dispersed in a solvent to form a suspension. Suitable solvents are any known solvents which are capable of achieving the above-described purpose of uniformly dispersing the particles and which do not substantially react with the particles or other components of the manufacturing process, which may be organic solutions or aqueous solutions including, but not limited to, water and C _{1- 6 alcohols} , preferably water and methanol, ethanol and aqueous solutions thereof. One of the methods of natural gravity sedimentation, centrifugation, vacuum pumping, or electrophoresis can be used to drive the particles to self-assemble to form a three-dimensional ordered microstructure in which a plurality of particles are densely packed. In a preferred embodiment, the suspension is placed in a long tubular mold to form a three-dimensional ordered microstructure having a high aspect ratio for subsequent use of the three-dimensional ordered microstructure for stenciling to have a high depth and width. The three-dimensional ordered porous microstructure.

The inventors of the present application have found that when a chemical or physical treatment is applied to the three-dimensional ordered microstructure to deform the particles located therein, adjacent particles in the three-dimensional ordered microstructure will be deformed by each other. The increased contact area between the three leads to a three-dimensional ordered microstructure with a relatively compact structure. The term "deformation" as used in this specification encompasses any chemical or physical treatment that enables a substantial change in the shape of the particles in a three-dimensional ordered microstructure. In a specific embodiment using substantially spherical particles, the particles are close to a true sphere before being deformed, and deformed to be in contact with adjacent particles after being subjected to chemical or physical treatment, thereby having a longest radius R and a shortest radius r, wherein the ratio of r/R is greater than /2 but less than 1. Suitable processing steps can be selected depending on the material of the particles, including but not limited to heat, pressure, dissolution, and the like.

In a preferred embodiment, step B comprises heating the three-dimensional ordered microstructure to soften the plurality of particles to undergo deformation. As used herein, the term "softening" means that the ordered particles are deformed by heat and bonded to each other. The softening of the particles can be observed and measured under an electron microscope. Figure 2 shows polystyrene spherical particles that have not been softened by heat and have a shape close to the true sphere. Figure 3 shows that the polystyrene particles arranged in the closest packed form are softened by heating and begin to deform. At this time, the contact area between each particle and the adjacent particle increases. Taking softened spherical particles as an example, the ratio of the shortest radius r to the longest radius R will be greater than /2 but less than 1, ie . For example, the particles shown in Figure 3 have an r/R ratio of about 0.94. The contact area between adjacent particles in the three-dimensional ordered microstructure is related to the size of the interconnected pores between the macropores in the three-dimensional ordered porous microstructure. In other words, the smaller the ratio of r/R, the larger the pore size of the communicating pores relative to the pore size in the three-dimensional ordered porous microstructure prepared in the present application, and the pore diameter of the communicating pores is approximately equal to 2r/ . In a preferred embodiment, the r/R is less than or equal to 0.99, preferably less than or equal to 0.98, more preferably less than or equal to 0.96, such as less than or equal to 0.94. Non-spherical particles, such as elliptical particles, have an r/R ratio that tends to decrease as they are softened by heat. Figure 4 shows that the polystyrene spherical particles are deformed by heat for a long time, so that the individual particles are completely in close contact with the adjacent six particles, and there is no pore between them, forming an approximately hexagonal configuration, and this structure cannot be used as a structure. Anti-structured template. Thus, in the present application, the degree of softening of the particles can be controlled by adjusting the temperature and/or time of heating to maintain proper porosity between the particles.

As is known to those of ordinary skill in the relevant art, when the micron or nanoscale particles used herein are made of a crystalline material, they will begin to melt at a temperature above the melting point. When the micron or nanoscale particles used in the present application are made of an amorphous material, they may have a glass transition temperature. As used herein, the term "glass transition temperature", or abbreviated as " _Tg ", means that the material constituting the particle is converted from a rigid glassy state to a soft, flexible rubbery state. (rubbery state) temperature. The glass transition temperature can be measured by differential scanning calorimetry according to ASTM-E1356. T _g polymer material may be known by other copolymerizable monomers, changing the degree of branching, the chain length adjustment, adjustment of the degree of crosslinking, adding a plasticizer or the like means to change. For example, commercially available styrene homopolymer sphere particles have a _{Tg of} about 105 ^o C. As shown in Example 1-6, by making different monomers copolymerizable with styrene, can effectively reduce the T _g of polystyrene spherical particles.

Known in the prior art, spherical particles at a temperature above its T _g will exhibit rubbery melted deformed, hard sphere form at temperatures below its T _g of the presentation will be. Accordingly, the heating step B is a preferred embodiment, the particles are in a higher temperature as compared to its glass transition temperature from about 0 to 20 ^o C, the heating period of time, so that the particles soften. Since the particles will deform rapidly in their rubbery state, the heating time is usually short-lived, for example in the range of seconds to minutes. It is preferred to use particles having a large particle size, for example, particles having a particle diameter of more than 1 micrometer are used to prevent the particles from deforming too fast. After heating, the temperature can be lowered to a lower temperature T _g as compared to the particles, the particles return to its glassy state, and utilizes volatile at this temperature, vacuum exhaust, etc. for removal of suspended particles in step A Solvent.

The inventors of the present application have unexpectedly discovered that after the particles are heat treated for a period of time at a temperature about 1 to 15 ^o C lower than their glass transition temperature, although the particles are not converted to their rubbery state, they are presented. Softening phenomenon. While not wishing to be bound by theory, the inventors believe the present application, a material constituting the particles at a temperature close to its T _g, wherein the molecule will receive enough energy to start to flow, resulting in a slight softening particles. In a particular embodiment where the particles used are homogeneous spheres made from a single type of polymeric homopolymer or copolymer, the glass transition temperature refers to the bulk glass transition temperature (bulk _Tg ) of the particles. In a specific embodiment in which the particles used have a core-shell structure, the core of the particles may be made of a homopolymer of a monomer such as styrene, and the outer shell may be from the monomer to another monomer ( For example, a copolymer of butyl methacrylate). In this case, the glass transition temperature T _g refers to housing, which may be lower than the core T _g, so that the core than in the above temperature range to soften more easily.

Accordingly, in another preferred embodiment of the heating step B, the particles are at a temperature which is about 1 to 15 ^o C lower than the glass transition temperature, preferably in a phase compared to the T _{g of the} particles. At a temperature of about 3 to 10 ^o C lower, for example, at a temperature of about 3 to 5 ^o C lower than the T _{g of the} particles, heating is carried out for a period of time to soften the particles, preferably simultaneously in step A. A solvent used to suspend particles. In order to avoid the solvent being heated too fast to destroy the three-dimensional ordered microstructure, the heating temperature is preferably selected to be a temperature substantially lower than the boiling point of the solvent but allowing the solvent to be effectively volatilized. In a specific embodiment using water or a C _{1-6 alcohol} such as water, methanol, ethanol or an aqueous solution thereof as a solvent, since the solvent used has a low boiling point, it is preferably used for constructing a three-dimensional ordered microstructure. The particles are particles having a low _Tg in order to select a heating temperature in step B which simultaneously softens the particles and removes the solvent. In a preferred embodiment, the _Tg of the particles is in the range of 0 ^o C to 100 ^o C, more preferably in the range of 50 ^o C to 95 ^o C, most preferably in the range of 60 ^o C to 90 Within the range of ^o C, for example, in the range of 75 ^o C to 85 ^o C. The heating time is not particularly limited as long as the purpose of softening the particles and removing the solvent is achieved. In general, the lower the heating temperature, the longer the heating time must be, in order to achieve the above object. The heating time may be from several minutes to several days, preferably from several tens of minutes to one day, to achieve mass production.

In another preferred embodiment, step B includes applying pressure to the three-dimensional ordered microstructure to cause the plurality of particles to deform against one another. The process of applying pressure includes, but is not limited to, centrifugation, vacuum pumping, etc., to apply pressure (e.g., 5,000 psi or more) to the particles in the same direction. The solvent used to suspend the particles in the step A is then removed by means of volatilization, vacuum evacuation or the like. In this embodiment, it is preferred that the particles have a core-shell structure in which the outer shell is soft and the core is hard so that when the particles are pressed against each other due to pressure, the soft outer shell is deformed, resulting in contact between the particles. The area increases and the ratio of r/R falls /2 to 1 range.

In another preferred embodiment, step B comprises immersing the three-dimensional ordered microstructure in a solvent capable of dissolving the plurality of particles, causing the plurality of particles to swell and deform. Preferably, the solvent for suspending particles in the step A is removed in advance by volatilization, vacuum evacuation or the like before the step B is carried out. In a specific embodiment in which the particles used are made of a polymer material, it is preferred that the solvent is an organic solvent, more preferably a solvent system obtained by mixing an organic solvent with water to appropriately reduce the solubility to the particles. . In a particular embodiment where the particles are made from a homopolymer or copolymer of a styrene monomer, the solvents include, but are not limited to, styrene, toluene, chlorocyclohexane, and mixtures thereof with water. In a specific embodiment in which the particles are made of a homopolymer or a copolymer obtained by polymerizing a methacrylate monomer, the solvent includes, but is not limited to, a C _{1-4 alcohol,} 1,4-dioxane. , benzene, n-hexane and their mixture with water. Organic solvents such as acetone, methyl ethyl ketone, dimethylformamide, ethyl acetate, and the like, and mixtures thereof with water can also be used. When the three-dimensional ordered microstructure is immersed in a solvent, the molecular chain on the surface of the particle will start to loose due to contact with the solvent, causing the particles to slightly swell, resulting in an increase in the contact area between the particles and the ratio of r/R. Fall in /2 to 1 range. The contact area between the particles can be adjusted by adjusting the soaking time and/or the soaking temperature.

In step C of filling the voids, the anti-structural material is filled into the voids of the three-dimensional ordered microstructure. The anti-structural materials include, but are not limited to, metals such as gold, silver, copper, nickel, platinum, nickel tungsten alloys, etc.; oxides such as zinc oxide, cerium oxide, cuprous oxide, etc.; and polymeric materials such as polyphenylene. Ethylene, polyacrylates, polymethacrylates, acrylamides, polypyrroles, polyethylenes, polypropylenes, polyvinyl chlorides, silicones, and the like. In a specific embodiment for producing a monolithic column, preferably the anti-structural material is selected from the group consisting of polymeric hydrogels, which are composed of acrylamides, acrylates, methacrylates, A hydrophilic monomer such as a siloxane is polymerized. Preferred polymeric hydrogels include polyhydroxyethyl methacrylate (PHEMA), polyglycidyl methacrylate (PGMA), polydimethyl methoxy oxane (PDMS), polypropyl acrylamide, and derivatives thereof. Things. The anti-structural material may be filled by centrifugation, vacuum evacuation, pressure extrusion, sputtering, electroplating, chemical vapor deposition, atomic layer deposition, and the like. In a specific embodiment in which the anti-structural material is a polymer material, the monomer or precursor constituting the polymer material may be first filled into a void and then solidified and shaped.

In the step of removing the three-dimensional ordered microstructure, the particles in the three-dimensional ordered microstructure are removed after the material to be deformed is shaped. The manner of removal is well known in the art and includes, but is not limited to, chemical removal, high temperature removal, and the like. For example, in a conventional chemical removal method, a chemical agent capable of dissolving particles such as toluene, acetone, ethyl acetate, hydrofluoric acid, or sodium hydroxide can be used to treat a film-type microstructure to cause particles to be detached from the anti-structure. material. However, when a conventional process such as immersion or extraction is used to process a microstructure having a high aspect ratio, a problem that the stencil is not easily removed will occur. In addition, the anti-structural material used in the fabrication of the monolithic column is a polymer material that cannot withstand high temperatures, and is therefore not suitable for removing the stencil via high temperature removal.

The inventors of the present application have unexpectedly discovered that the use of supercritical fluid extraction by Soxhlet extraction or supercritical fluid extraction can overcome the problem of the microstructure being difficult to remove due to the high aspect ratio. Accordingly, in a preferred embodiment of the present application, the three-dimensional ordered microstructure is removed using a method selected from the group consisting of Soxhlet extraction and supercritical fluid extraction. As used herein, the term "Soxhlet extraction" means that the microstructure is placed in a Soxhlet extractor, the solvent used to dissolve the stencil is heated to reflux, and the stencil material is continuously extracted from the microstructure. Generally, the Soxhlet extraction method uses a temperature higher than the boiling point of the solvent used to dissolve the stencil, and the extraction time lasts for about 3 to 7 days. As used herein, the term "supercritical fluid extraction" means dissolving a stencil material with a supercritical fluid at a temperature above a critical temperature and a critical pressure, and then dissolving it in excess by reducing the pressure or increasing the temperature. The stencil material in the critical fluid is precipitated. In a preferred embodiment, CO _{2 is used} as a supercritical fluid, and a co-solvent such as acetone, toluene or ethyl acetate is used to remove the polystyrene-based stencil material.

The three-dimensional ordered porous microstructures made in accordance with the methods of the present application can be subjected to additional processing to produce a variety of commercial products. In a preferred embodiment, the three-dimensional ordered porous microstructure can be subjected to conventional processes such as cutting, encapsulation, and/or chemical modification to have appropriate surface functionality to form a monolithic column for use as a Chromatographic separation of stationary phase materials. The term "monolithic column" as used in the present application includes a continuous medium composed of the foregoing anti-structural material, which is formed with a plurality of ordered spherical macropores having a uniform diameter of between 100 nm and 6 μm and a plurality of connections. The communicating pores of the macropores have a uniform diameter of between 10 nm and 3 microns. In a preferred embodiment, the spherical macropores are arranged in the closest packed form, in which case each macropores may be in communication with adjacent macropores via 12 communicating holes. Preferably, at least 70% of the macropores, more preferably at least 80% of the macropores, more preferably at least 90% of the macropores, for example at least 95% of the macropores, are in the most closely packed form. arrangement. The ratio of the longest radius R of the giant hole to the shortest radius r can be inequality To represent. The smaller the ratio of r/R, the larger the pore size of the communicating pores relative to the pore size in the three-dimensional ordered porous microstructure, wherein the pore diameter of the communicating pores is approximately equal to 2r/ . In a preferred embodiment, the interconnected pores within the column have a large pore size, i.e., the r/R is less than or equal to 0.99, preferably less than or equal to 0.98, more preferably less than or equal to 0.96, such as less than or equal to 0.94. The monolithic column may further comprise a hollow tubular body which may be made of a material such as stainless steel, quartz or glass and has an inner wall for the continuous medium to adhere. In a preferred embodiment, the monolithic column has a height of at least 1 cm, such as a height of at least 3 cm or at least 5 cm, and has an aspect ratio of not less than 1, such as not less than 2.5 or not less than 3 aspect ratio. By "aspect ratio" is meant herein the ratio of the column height to the diameter of the monolithic column.

The following examples are intended to illustrate and not to limit the scope of the invention.

Example 1 : Preparation of polystyrene - butyl methacrylate nanospheres A butyl methacrylate monomer solution was added to a styrene monomer solution (99.6 parts by weight), and the system solid content was formulated to be 10% by weight. The mixture was stirred at 350 rpm for 1 hour and the temperature was maintained at 65 °C. Next, 0.25 g of potassium sulfate was added to the mixture to start the polymerization. After 16 hours, the monomer was completely consumed. In the present embodiment, the glass transition temperature of the polystyrene particles can be adjusted to be in the range of 82 ^o C to 26 ^o C by controlling the amount of the butyl methacrylate solution to 10 to 30 ml.

Example 2 : Preparation of polystyrene - butyl acrylate nanospheres A butyl acrylate monomer solution was added to a styrene monomer solution (99.6 parts by weight), and the system solid content was formulated to 10% by weight. The mixture was stirred at 350 rpm for 1 hour and the temperature was maintained at 65 °C. Next, 0.25 g of potassium sulfate was added to the mixture to start the polymerization. After 16 hours, the monomer was completely consumed. In the present embodiment, the glass transition temperature of the polystyrene particles can be adjusted to be in the range of 50 ^o C to 0 ^o C by controlling the amount of the butyl acrylate solution to 10 to 30 ml.

Example 3 : Preparation of poly ( styrene - butyl methacrylate) core-shell structure nanospheres A styrene monomer solution (99.6 parts by weight) was formulated to have a solid content of 10% by weight. The mixture was stirred at 350 rpm for 1 hour and the temperature was maintained at 65 °C. Next, 0.25 g of potassium sulfate was added to the mixture to start the polymerization. After the reaction has been carried out for a certain period of time, a butyl methacrylate monomer solution is added to the system for shell construction to form a shell layer made of a styrene-butyl methacrylate copolymer. In the present embodiment, by controlling the amount of the butyl methacrylate monomer solution to 10 to 30 ml, the glass transition temperature of the shell layer can be adjusted to be in the range of 40 ^o C to 26 ^o C.

Example 4 : Preparation of poly ( styrene - butyl acrylate) core-shell structure nanospheres A styrene monomer solution (99.6 parts by weight) was formulated to have a solid content of 10% by weight. The mixture was stirred at 350 rpm for 1 hour and the temperature was maintained at 65 °C. Next, 0.25 g of potassium sulfate was added to the mixture to start the polymerization. After the reaction has been carried out for a certain period of time, a butyl acrylate monomer solution is added to the system for shell construction to form a shell layer made of a styrene-butyl acrylate copolymer. In the present embodiment, by controlling the amount of the butyl acrylate monomer solution to 10 to 30 ml, the glass transition temperature of the shell layer can be adjusted to be in the range of 10 ^o C to 0 ^o C.

Example 5 : Preparation of poly ( butyl methacrylate - styrene ) core-shell structured nanospheres A solution of butyl methacrylate monomer (99.6 parts by weight) was formulated to have a solid content of 10% by weight. The mixture was stirred at 350 rpm for 1 hour and the temperature was maintained at 65 °C. Next, 0.25 g of potassium sulfate was added to the mixture to start the polymerization. After the reaction has been carried out for a certain period of time, a styrene monomer solution is added to the system for shell construction to form a shell layer made of a styrene-butyl methacrylate copolymer. In the present embodiment, by controlling the amount of the styrene monomer solution to 10 to 30 ml, the glass transition temperature of the shell layer can be adjusted to be in the range of 50 ^o C to 80 ^o C.

Example 6 : Preparation of poly ( butyl acrylate - styrene ) core-shell structure nanospheres A butyl acrylate monomer solution (99.6 parts by weight) was formulated to have a solid content of 10% by weight. The mixture was stirred at 350 rpm for 1 hour and the temperature was maintained at 65 °C. Next, 0.25 g of potassium sulfate was added to the mixture to start the polymerization. After the reaction has been carried out for a certain period of time, a styrene monomer solution is added to the system for shell construction to form a shell layer made of a styrene-butyl acrylate copolymer. In the present embodiment, by controlling the amount of the styrene monomer solution to 10 to 30 ml, the glass transition temperature of the shell layer can be adjusted to be in the range of 50 ^o C to 80 ^o C.

Example 7 : Preparation of three-dimensional ordered microstructure A 30% aqueous methanol solution was prepared, and the boiling point of water was about 95 ^o C when measured. Prepared in Example 1 nanospheres are suspended in the aqueous methanol solution in which the nanospheres glass transition temperature of 80 ^o C, a particle size of 600 nm. The suspension was placed in a centrifuge tube having an inner diameter of 1.6 cm, and the nanospheres were allowed to self-assemble until the nanospheres were filled with the centrifuge tube to form a columnar three-dimensional ordered microstructure having a length of 4 cm and a diameter of 1.6 cm. The tubes were placed in a hot-air DENG YNG DO60 loop oven, (compared to the low T _g of nanospheres 3 ^o C) was heated at 77 ^o C in a three-dimensionally ordered microstructure dried for 30 minutes to remove the solvent . 5 shows a three-dimensional ordered microstructure prepared according to the present embodiment, in which the nanospheres arranged in the hexagonal closest packing are slightly deformed and slightly hexagonal, so that there is a large area contact between adjacent nanospheres. It is suitable for use as a stencil to make a monolithic column.

Example 8 : Preparation of three-dimensional ordered porous microstructure A hydroxyethyl methacrylate (HEMA) precursor was placed in a centrifuge tube using the three-dimensional ordered microstructure prepared in Example 7 as a stencil. Applying centrifugal stencil causes HEMA filled pores, and then cured at 55 ^o C water bath. After the curing is completed, the structure is taken out, cut to a diameter corresponding to a stainless steel HPLC column, and the structure is tightly bonded to the wall of the HPLC column with an encapsulant. The structure encapsulated in the column was subjected to Soxhlet extraction, and the extract was continuously refluxed for 5 days with toluene, and the viscosity of the solvent was maintained at 0.2 to 0.6 psi during the extraction, thereby removing the stencil to obtain a monolithic finished product. Figure 6 shows that the Soxhlet extraction method of the present embodiment allows the solvent to easily enter pores below the micrometer scale, thereby dissolving the particles and carrying the microstructure, thereby completely removing the stencil material. According to the three-dimensional ordered porous microstructure produced in the present embodiment, spherical macropores having a diameter of 600 nm arranged in the closest packed form and communicating pores having a diameter of 250 nm which are connected to the macropores are formed. Relatively speaking, as shown in Fig. 7, the conventional immersion method cannot completely remove the stencil material.

Example 9 : Preparation of three-dimensional ordered microstructures and three-dimensional ordered porous microstructures The preparation procedure of Examples 7 and 8 was repeated, but the heating temperature of the three-dimensional ordered microstructure was lowered to 65 ^o C (compared to nanospheres) T _{g is} 15 ^o C) and lasts 120 minutes. Fig. 8 shows a three-dimensional ordered porous microstructure formed in which spherical macropores arranged in the closest packed form and having a diameter of 600 nm, and communicating pores communicating with macropores and having a diameter of 150 nm were formed.

Example 10 : Preparation of three-dimensional ordered microstructure The procedure of the preparation of Example 7 was repeated, and the nanospheres prepared in Example 1 were also used, but the particle diameter was 1 μm, and the heating temperature of the three-dimensional ordered microstructure was raised. up to 100 ^o C (compared to the high T _g of Na Nami ball 20 ^o C), heated for 3 min. The temperature was then lowered to 75 ^o C (compared to the low T _g of nanospheres 5 ^o C), the three-dimensional ordered microstructure dried by heating for 30 minutes to remove the solvent. 9 shows a three-dimensional ordered microstructure prepared according to the present embodiment, in which the nanospheres arranged in the hexagonal closest packing are slightly deformed and slightly hexagonal, so that there is a large area contact between adjacent nanospheres. It is suitable for use as a stencil to make a monolithic column.

Comparative Example 1: Preparation of three-dimensional ordered microstructure preparation step was repeated Example 7, but the heating temperature is lowered to a three-dimensional ordered microstructure 60 ^o C (compared to the low T _g of nanosphere 20 ^o C). After drying for 30 minutes, most of the solvent was still not removed. The final drying time was 80 minutes. Fig. 10 shows a three-dimensional ordered microstructure prepared according to the present comparative example, in which the nanospheres are arranged in the hexagonal closest packing, and the respective nanospheres are still substantially spherical, and the contact between them is not obvious.

Comparative Example 2: Preparation of three-dimensional ordered microstructure preparation step was repeated Example 7, but the heating temperature of the three-dimensional ordered microstructure was raised to 90 ^o C (as compared to the high T _g of nanosphere 10 ^o C), Dry for 15 minutes. Fig. 11 shows a three-dimensional ordered microstructure prepared according to the present comparative example, in which the nanospheres are arranged in the most densely packed hexagonal shape, are substantially hexagonal, and are completely in close contact with each other without voids. This structure cannot be used as a template.

Comparative Example 3: Preparation of three-dimensional ordered microstructure Preparation procedure of Example 7 was repeated, but the three-dimensional ordered microstructure heating temperature was raised to 110 ^o C (as compared to the high T _g of nanosphere 30 ^o C), Dry for 10 minutes. Fig. 12 shows a three-dimensional microstructure prepared according to the present comparative example, in which the nanospheres are melted at a high temperature, the shape is difficult to recognize, and they are completely in close contact with each other without a gap. This structure cannot be used as a template.

Compared with the conventional conventional method, the three-dimensional ordered porous microstructure manufacturing method disclosed in the present invention heats a three-dimensional ordered microstructure at a temperature slightly lower than the glass transition temperature of the particles to remove the solvent for the suspended particles. And effectively enhance the contact between the ordered particles. Compared with the monolithic column produced by the conventional method, the monolithic column produced according to the manufacturing method has the structural characteristics of high aspect ratio and high hole regularity, and the communication hole in the column also has a relatively large aperture.

The above embodiments are intended to be illustrative of the present invention, and are not intended to limit the scope of the invention, and various modifications and changes may be made without departing from the scope of the invention.

R‧‧‧ longest radius

R‧‧‧ shortest radius

1 is a flow chart according to an embodiment of the present invention; FIG. 2 is an electron micrograph of polystyrene particles which are not softened by heating; FIG. 3 is an electron micrograph of polystyrene particles which are softened by heating, which shows that particles start FIG. 4 is an electron micrograph of a polystyrene particle which is thermally deformed for a long time; FIG. 5 is an electron micrograph of a three-dimensional ordered microstructure prepared according to an embodiment of the present invention; FIG. 6 shows an embodiment of the present invention. Cross-section electrical photographs of three-dimensional ordered porous microstructures fabricated by Soxhlet extraction to remove three-dimensional ordered microstructures; Figure 7 shows three-dimensional ordered porous pores prepared by conventional soaking methods to remove three-dimensional ordered microstructures Electron micrograph of microstructure; Figure 8 shows a cross-sectional electrical photograph of a three-dimensional ordered porous microstructure made in accordance with another embodiment of the present invention; Figure 9 shows a three-dimensional ordered microstructure made in accordance with another embodiment of the present invention Figure 10 is a cross-sectional electrical photograph of a three-dimensional ordered microstructure made according to a comparative example; Figure 11 is a three-dimensional order made according to another comparative example. Significant electrical configuration of a cross-sectional photograph; and a cross-sectional three-dimensional ordered microstructure electrically FIG. 12 shows another comparative example was fabricated picture.

Claims (6)

A monolithic column comprising: a plurality of ordered spherical macropores having a uniform diameter of between 100 nanometers and 6 micrometers; and a plurality of interconnecting pores connected to the macropores having a uniformity between 10 nanometers and 3 micrometers Diameter; wherein at least 80% of the macropores are arranged in the closest packed form, and the macropores have a longest radius R and a shortest radius r, wherein the ratio of r/R is less than or equal to 0.99. The monolithic column of claim 1, wherein at least 90% of the macropores are arranged in a densely packed form. The monolithic column of claim 2, wherein at least 95% of the macropores are arranged in a most closely packed form. The monolithic column of claim 1, wherein the ratio of r/R is less than or equal to 0.98. The monolithic column of claim 4, wherein the ratio of r/R is less than or equal to 0.96. The monolithic column according to any one of claims 1 to 5, which has a height of at least 1 cm and has an aspect ratio of not less than 1.