Preparation method of ordered spaced microporous structure and microsphere array

Abstract

The invention provides a preparation method of an ordered spaced microporous structure, which comprises the following steps: firstly, coating a substrate with a separant to obtain a substrate with a separant layer, and then constructing monodisperse template microspheres which are arranged in a single-layer array on the separant layer of the substrate to obtain a single-layer microsphere template; and pouring the polymer precursor solution on the template microspheres of the single-layer microsphere template, curing, demolding, and removing the separant and the template microspheres attached to the cured polymer, thereby obtaining the polymer template with the ordered interval microporous structure. Based on the ordered spaced microporous structure, the invention also provides a preparation method of the microsphere array. According to the method, the problems that an existing processing method of the high-dimensional-precision ordered interval micropore structure needs to depend on expensive equipment, the preparation condition is harsh and the process is complex can be solved, and simple and efficient preparation of the ordered interval micropore structure and the microsphere array is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of micro-structure manufacturing and processing for electronic chips, chemical engineering, chemistry and other fields, and relates to a preparation method of an ordered spaced microporous structure and a microsphere array. Background Art

[0002] The microporous structure and the microsphere array usually present a two-dimensional or three-dimensional periodic distribution form, endowing the material with high orderliness and precise controllability. By changing the size, shape and spacing of the micropores or microspheres, the physical and chemical properties of the material can be precisely regulated, and it has broad application prospects in the fields of electronic packaging, energy conversion, chemical reaction, biomedicine, optical devices, environmental monitoring and microfluidics. Especially in the field of electronic packaging, the application of such a structure in an anisotropic conductive film (ACF) is particularly important. ACF is composed of conductive microspheres and cross-linked polymers, and connects the chip and the circuit board by using vertical conductivity and horizontal insulation. However, the microspheres in traditional ACF are disorderly distributed, which easily leads to uneven contact area and even short circuit, affecting the reliability and safety of the connection. Therefore, it is particularly crucial to develop an ACF with an equally spaced microsphere array.

[0003] Currently, the method widely used to construct an equally spaced microsphere array is the template-assisted assembly method, that is, using a template with a specific ordered spaced microporous structure to assist microsphere filling. These microporous structures are often constructed by techniques such as reactive ion etching, laser etching, electron beam etching, nanoimprinting and soft lithography. Typically, the reactive ion etching technique is to generate plasma by exciting hydrogen fluoride or oxygen with a radio frequency power supply in a vacuum environment, and use the plasma to bombard the surface of the substrate at a high speed vertically or obliquely, so that a chemical reaction occurs and volatile products are generated, and the volatile products are pumped away by a vacuum system, that is, a microporous structure is formed on the substrate; electron beam etching is to scan point by point on a silicon wafer with extremely high precision and resolution by precisely controlling the acceleration voltage, beam current and scanning speed of the electron beam system, and then remove the residues through operations such as chemical cleaning, heat treatment or ion bombardment, and finally form a fine microporous structure; the soft lithography technique mainly prepares a patterned template through steps such as spin coating, pre-baking, ultraviolet light exposure and development. The operation process is relatively simple, but it still relies on expensive instruments and has slightly insufficient precision, and is usually applicable to the construction of microporous structures with a scale of several hundred micrometers. In summary, the traditional high-precision ordered spaced microporous structure processing technology often relies on expensive equipment, harsh preparation conditions and complex process flows, and these factors significantly limit its further industrial application. Therefore, there is still a need to develop a simple and efficient preparation technology for ordered spaced microporous structures. Summary of the Invention

[0004] In view of the problems that the prior art relies on expensive equipment, harsh preparation conditions and complex process flows when preparing an ordered spaced microporous structure with high dimensional accuracy, the present invention provides a method for preparing an ordered spaced microporous structure and a microsphere array to achieve simple and efficient preparation of the ordered spaced microporous structure and the microsphere array.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing an ordered spaced microporous structure, comprising the following steps:

[0007] (1) Coat a layer of release agent on a cleaned and dried substrate to obtain a substrate with a release agent layer; the release agent is fatty acid, paraffin oil, petrolatum, silicone oil, polyvinyl alcohol or fluororesin coating;

[0008] (2) Construct monodisperse template microspheres arranged in a single-layer array on the release agent layer of the substrate to obtain a single-layer microsphere template; the thickness of the isolation layer is 4% - 50% of the diameter of the template microspheres;

[0009] (3) Pour a polymer precursor solution on the template microspheres of the single-layer microsphere template to form a casting layer, cure the polymer precursor solution to form a polymer, demold, and remove the release agent and template microspheres attached to the cured polymer to obtain a polymer template with an ordered spaced microporous structure.

[0010] In step (2) of the technical solution of the above method for preparing an ordered spaced microporous structure, a single-layer microsphere template is prepared by a method including gas-liquid interface self-assembly method, convective self-assembly method, etc.

[0011] In step (2) of the technical solution of the above method for preparing an ordered spaced microporous structure, the operation of preparing a single-layer microsphere template by the gas-liquid interface self-assembly method is as follows:

[0012] Perform oxygen plasma treatment on the substrate with a release agent layer, then immerse it in an aqueous solvent in a container with the side of the substrate provided with the release agent layer facing the liquid surface, slowly drop a template microsphere suspension on the liquid surface until the liquid surface is covered with a closely packed template microsphere film layer, then drop a water-soluble surfactant solution into the container to make the template microspheres closely arranged on the liquid surface, then take out the substrate from the container. During the process of taking out the substrate, keep the side of the substrate provided with the isolation layer always parallel to the liquid surface. After the solvent on the taken-out substrate is completely volatilized, a single-layer microsphere template with the template microspheres arranged in a single-layer array on the substrate is obtained.

[0013] In step (2) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, when preparing the monolayer microsphere template by the gas-liquid interface self-assembly method, the aqueous solvent is water, an aqueous solution of a water-soluble salt or an aqueous solution of a water-soluble polymer. The concentration of the aqueous solution of the water-soluble salt is 2 wt% to 10 wt%, and the water-soluble salt can be sodium chloride, potassium chloride, etc. The concentration of the aqueous solution of the water-soluble polymer is 2 wt% to 10 wt%, and the water-soluble polymer can be polyvinyl alcohol, polyurethane, etc. When the particle size of the template microspheres is relatively large (such as greater than 10 μm) or the density is relatively large, the template microspheres tend to sink to the bottom of the container due to their own large gravity and it is not easy to form a uniform template microsphere film layer on the liquid surface. At this time, an aqueous solution of a water-soluble salt or an aqueous solution of a water-soluble polymer can be used as the aqueous solvent. Using the aqueous solution of a water-soluble salt as the aqueous solvent can increase the density of the aqueous solvent in the container, and using the aqueous solution of a water-soluble polymer as the aqueous solvent can increase the viscosity of the aqueous solvent in the container, thereby preventing the template microspheres from sinking and helping the template microspheres to form a uniform template microsphere film layer on the liquid surface.

[0014] In step (2) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, when preparing the monolayer microsphere template by the gas-liquid interface self-assembly method, in the template microsphere suspension, the concentration of the template microspheres is preferably 1 wt% to 10 wt%. The solvent used to prepare the template microsphere suspension is water, an organic solvent or a mixed solution of water and an organic solvent. The organic solvent can be ethanol, ethylene glycol, etc. When the solvent used to prepare the template microsphere suspension contains an organic solvent, when the organic solvent volatilizes from the liquid surface, an upward force can be exerted on the template microspheres at the liquid surface, which helps to prevent the template microspheres from sinking.

[0015] In step (2) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, when preparing the monolayer microsphere template by the gas-liquid interface self-assembly method, the concentration of the water-soluble surfactant solution is preferably 2 wt% to 8 wt%, and the surfactant can be sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, potassium dodecyl sulfate, etc.

[0016] In step (2) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, when preparing the monolayer microsphere template by the gas-liquid interface self-assembly method, the water-soluble surfactant is added dropwise to the container, and while adding, observe. When the template microspheres are closely arranged on the liquid surface, stop adding.

[0017] In step (2) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, the operation of preparing the monolayer microsphere template by the convection self-assembly method is as follows:

[0018] The substrate with an isolation layer is subjected to oxygen plasma treatment, and then placed on a hot stage at 60-100 °C with the side of the substrate provided with the isolation layer facing upward. A template microsphere suspension is dropped onto the isolation layer of the substrate, and the template microsphere suspension is scraped in the same direction by means of doctor blading. During the process of the solvent of the template microsphere suspension being heated and evaporated, forces including capillary force and surface tension induce the template microspheres to be uniformly arranged along the doctor blading direction. After the solvent of the template microsphere suspension is completely evaporated, a monolayer microsphere template with the template microspheres arranged in a monolayer array on the substrate is obtained.

[0019] In step (2) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, when preparing the monolayer microsphere template by the convective self-assembly method, it is preferably to control the moving speed of the squeegee during doctor blading at a constant speed of 0.1-5.0 μm / s.

[0020] In step (2) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, when preparing the monolayer microsphere template by the convective self-assembly method, in the template microsphere suspension, the concentration of the template microspheres is preferably 0.1 wt% - 0.5 wt%. The solvent used to prepare the template microsphere suspension is water, an organic solvent or a mixed solution of water and an organic solvent, and the organic solvent can be ethanol, ethylene glycol, etc.

[0021] In the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, the thickness of the isolation layer is 4% - 50% of the diameter of the template microspheres.

[0022] In the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, the template microspheres in step (2) are inorganic microspheres or organic microspheres; when the template microspheres in step (2) are organic microspheres, the material of the template microspheres is different from the material of the polymer formed after curing the casting layer in step (3). The inorganic microspheres can be calcium carbonate (CaCO3) microspheres, metal microspheres, metal oxide microspheres, silicon dioxide (SiO2) microspheres, and the organic microspheres can be polystyrene (PS) microspheres, polymethyl methacrylate (PMMA) microspheres, but the feasible template microspheres are not limited to the microspheres of the specific materials listed above.

[0023] In step (3) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, the template microspheres attached to the polymer obtained by curing can be removed by mechanical means such as ultrasonic treatment, water washing, gas purging, etc., or the template microspheres attached to the polymer obtained by curing can be removed by selective dissolution with a solvent. The solvent used for selective dissolution of the template microspheres can dissolve the template microspheres but cannot dissolve the polymer formed by curing.

[0024] In the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, the thickness of the casting layer affects the mechanical strength of the finally prepared polymer template with the ordered spaced microporous structure. To ensure the integrity and stability of the prepared polymer template with the ordered spaced microporous structure during multiple uses, the thickness of the casting layer is at least 10 times the diameter of the template microspheres. Preferably, the thickness of the casting layer is at least 1 mm.

[0025] In step (3) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, the polymer formed by curing can be silicone rubber, polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polycarbonate (PC), polyurethane (PU), polyethylene (PE), etc. The material of the polymer formed by curing needs to be different from the material of the template microspheres.

[0026] In step (1) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, a release agent is coated on the planar region of the substrate to form a release agent layer.

[0027] In step (1) of the technical solution of the preparation method of the above-mentioned ordered spaced microporous structure, the substrate can be a quartz substrate or a silicon substrate.

[0028] The present invention has experimentally confirmed that on the basis of determining the size of the template microspheres, by adjusting the thickness of the isolation layer, the micropore size and spacing of the finally obtained ordered spaced microporous structure can be adjusted. As Figure 1 shown, with the change of the thickness of the release agent layer 2 provided on the substrate 1, the wrapping depth of the template microspheres 3 by the release agent layer 2 will change. After casting the polymer precursor solution to form a casting layer and curing, the wrapping depth of the cured polymer 4 on the template microspheres is also different. Therefore, after removing the template microspheres, in the obtained polymer template with the ordered spaced microporous structure, the size and spacing of the micropores will also change. Thus, the convenient and flexible regulation of the micropore size and spacing of the ordered spaced microporous structure can be realized. Figures (a), (b), and (c) of the figure show the influence of the change of the thickness of the isolation base layer on the micropore size and spacing. Of course, in the above technical solution of the present invention, the micropore size and spacing can also be adjusted by adjusting the particle size of the template microspheres, and the roughness of the micropores can also be adjusted by controlling the surface roughness of the template microspheres.

[0029] Based on the polymer template with the ordered spaced microporous structure prepared by the above technical solution of the preparation method of the ordered spaced microporous structure, the present invention also provides a preparation method of a microsphere array: filling conductive microspheres into the micropores of the polymer template with the ordered spaced microporous structure to realize the array arrangement of the conductive microspheres, and transferring the array-arranged conductive microspheres to a target substrate to obtain a microsphere array.

[0030] In the technical solution of the above preparation method of the microsphere array, in order to achieve the array arrangement of the conductive microspheres, it is necessary to ensure that each micropore is filled with one conductive microsphere. In order to ensure that each micropore is filled with one conductive microsphere, it is necessary to control the particle size of the conductive microspheres to be 0.7 to 1.5 times the diameter of the micropores on the polymer template with an ordered spaced micropore structure.

[0031] In the technical solution of the above preparation method of the microsphere array, the friction-assisted assembly microsphere method can be used to construct the microsphere array, that is, the conductive microspheres are placed on the side with the micropore structure of the polymer template with an ordered spaced micropore structure, and then a flexible block material (such as rubber, elastomer, polydimethylsiloxane, etc.) is gently rubbed several times (such as 5 to 10 times) along the same direction, so that the conductive microspheres can enter the micropores on the polymer template to achieve the array arrangement of the conductive microspheres in the polymer template. Finally, the arrayed conductive microspheres are transferred to the target substrate with commercial tape or resin film to obtain the microsphere array.

[0032] In the technical solution of the above preparation method of the microsphere array, the conductive microspheres are the conductive microspheres used in the prior art for preparing anisotropic conductive films. For example, gold-plated polystyrene microspheres, silver-plated polystyrene microspheres, nickel-plated polystyrene microspheres, nickel-plated polyurethane microspheres, copper-plated polystyrene microspheres, cobalt-plated polystyrene microspheres, etc.

[0033] The microsphere array prepared by the technical solution of the above preparation method of the microsphere array is a microsphere array in which the conductive microspheres are arranged at equal intervals, and the microsphere array can be used to prepare anisotropic conductive films.

[0034] The ordered spaced micropore structure prepared by the technical solution of the above preparation method of the ordered spaced micropore structure can be applied to superhydrophobic surfaces, optical devices, biological detection, chemical reactions, etc. in addition to being used to prepare microsphere arrays. The roughness of the micropore structure may affect these applications. According to the actual application requirements, the roughness of the micropore structure can be adjusted by adjusting the surface roughness of the template microspheres, etc., and then the surface properties can be adjusted to better meet the application requirements.

[0035] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects:

[0036] 1. The present invention provides a method for preparing an ordered spaced microporous structure. First, a release agent is coated on a cleaned and dried substrate to obtain a substrate with a release agent layer. Then, monodisperse template microspheres arranged in a single-layer array are constructed on the release agent layer of the substrate to obtain a single-layer microsphere template. Next, a polymer precursor solution is poured on the template microspheres of the single-layer microsphere template to form a pouring layer, and the polymer precursor solution is cured to form a polymer. After demolding, the release agent and the template microspheres attached to the cured polymer are removed to obtain a polymer template with an ordered spaced microporous structure. Compared with the existing methods for preparing an ordered spaced microporous structure with high dimensional accuracy by relying on chemical etching, laser etching, electron beam etching, nanoimprinting, and soft lithography, etc., the method of the present invention has the advantages of simple operation, high dimensional accuracy, large-area order, and no need to rely on complex equipment. Moreover, it has good process controllability and is easy to realize large-scale production. The present invention provides a new idea for the controllable preparation of an ordered spaced microporous structure with high dimensional accuracy.

[0037] 2. By adjusting the particle size of the template microspheres and the thickness of the release agent layer, the method of the present invention can flexibly control the micropore size and spacing of the ordered spaced microporous structure, and also has the advantage of convenient and flexible adjustment methods for the micropore size and spacing compared with the prior art.

[0038] 3. The ordered spaced microporous structure prepared by the method of the present invention can be used for the construction of a microsphere array, providing a simple and high-precision template for the array arrangement of conductive microspheres. Based on this, the present invention also provides a method for preparing a microsphere array. After filling the conductive microspheres into the micropores of the polymer template with the ordered spaced microporous structure to realize the array arrangement of the conductive microspheres, the arrayed conductive microspheres are transferred to a target substrate, thus realizing the convenient and efficient construction of the microsphere array.

[0039] 4. The ordered spaced microporous structure prepared by the method of the present invention can also be applied to superhydrophobic surfaces, optical devices, biological detection, chemical reactions, etc. The roughness of the microporous structure may affect these applications. According to the actual application requirements, the roughness of the microporous structure can be adjusted by controlling the surface roughness of the template microspheres, etc., so as to adjust the surface properties and better meet the application requirements. Description of the Drawings

[0040] Figure 1 is a schematic diagram of the process for the method of preparing the ordered spaced microporous structure of the present invention and the regulation of the size and spacing of the microporous structure. In the figure, 1 is the substrate, 2 is the release agent layer, 3 is the template microsphere, and 4 is the polymer obtained by curing.

[0041] Figure 2 Figure a of is the SEM image after demolding from the single-layer microsphere template in Example 1. Figure 2Figure b of [Example 1] is the SEM image of the PDMS template with an ordered and spaced microporous structure prepared in Example 1.

[0042] Figure 3 Figures a and b of [Example 2] are the SEM images of the PDMS template with an ordered and spaced microporous structure prepared in Example 2 at different magnifications.

[0043] Figure 4 Figures a and b of [Example 3] are the SEM images of the monolayer microsphere template after demolding in Example 3. Figure 4 Figures c and d of [Example 3] are the SEM images of the PDMS template with an ordered and spaced microporous structure prepared in Example 3.

[0044] Figure 5 Figures a and b of [Example 4] are the SEM images of the monolayer microsphere template after demolding in Example 4. Figure 5 Figures c and d of [Example 4] are the SEM images of the PDMS template with an ordered and spaced microporous structure prepared in Example 4.

[0045] Figure 6 Figures a and b of [Example 5] are the SEM images of the conductive microspheres arrayed and arranged in the microporous structure in Example 5. Figure 6 Figures c and d of [Example 5] are the SEM images of the equidistant microsphere array prepared in Example 5.

[0046] Figure 7 Figures a and b of [Example 6] are the SEM images of the conductive microspheres arrayed and arranged in the microporous structure in Example 6. Figure 7 Figures c and d of [Example 6] are the SEM images of the equidistant microsphere array prepared in Example 6.

[0047] Figure 8 Figures a and b of [Example 7] are the SEM images of the equidistant microsphere array prepared in Example 7. Detailed implementation mode

[0048] The following further illustrates the preparation method of the ordered and spaced microporous structure and microsphere array provided by the present invention through examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Those skilled in the art make some non-essential improvements and adjustments to the present invention according to the above invention content and implement it specifically, which still belongs to the protection scope of the present invention.

[0049] Example 1

[0050] In this example, a preparation method of an ordered and spaced microporous structure is provided, and the steps are as follows:

[0051] (1) Coat a release agent on the surface of the substrate

[0052] Using a quartz wafer as the substrate, the substrate was ultrasonically cleaned in deionized water, acetone, absolute ethanol, and deionized water in sequence for 8 - 20 min, and the cleaned substrate was placed in an oven at 60 °C for drying for 30 min. A fluororesin coating was uniformly coated on the upper surface of the cleaned and dried substrate by spin coating, and the thickness of the formed isolation layer was controlled to be 1.5 ± 0.5 μm to obtain a substrate with an isolation layer.

[0053] (2) Preparation of a single - layer microsphere template

[0054] The single - layer microsphere template was prepared by the gas - liquid interface self - assembly method, and the operation is as follows:

[0055] Using monodisperse polystyrene (PS) microspheres with a particle size of 5 μm as the template microspheres, the template microspheres were added to a mixed solution of deionized water and ethanol (the volume ratio of deionized water to ethanol is 1:3), and were fully dispersed to obtain a template microsphere suspension with a template microsphere content of 1 wt%. Sodium dodecyl sulfate (SDS) was dissolved in deionized water to obtain an SDS solution with an SDS concentration of 2 wt%.

[0056] The substrate with the isolation layer was treated in oxygen plasma for 1 min, and then immersed in deionized water in a container with the side of the substrate with the isolation layer facing the liquid surface and parallel to the liquid surface. The template microsphere suspension was slowly dropped onto the liquid surface until the liquid surface was covered by a closely packed template microsphere film layer. Then, the SDS solution was gradually dropped into the container until the template microspheres were closely arranged on the liquid surface. Finally, the substrate was slowly taken out of the container. During the taking - out process, the side of the substrate with the isolation layer was always kept parallel to the liquid surface, that is, the substrate was used to "fish" the template microsphere film layer on the liquid surface. The taken - out substrate was left standing with the isolation layer facing up until the deionized water and ethanol were completely volatilized, and a single - layer microsphere template with a single - layer array arrangement of template microspheres on the substrate was obtained.

[0057] (3) Preparation of a polydimethylsiloxane (PDMS) template with an ordered spaced microporous structure

[0058] The PDMS prepolymer and the curing agent were fully mixed at a mass ratio of 10:1 to obtain a PDMS prepolymer solution. The PDMS prepolymer solution was poured onto the single - layer microspheres of the single - layer microsphere template to form a casting layer, and the thickness of the casting layer was controlled to be 1 mm. Then, it was placed in a vacuum drying oven for vacuum degassing and maintained at 80 °C for 4 h to cure the PDMS prepolymer solution. The cured PDMS was carefully demolded from the single - layer microsphere template and placed in absolute ethanol for ultrasonic cleaning for 4 h to remove the residual isolation agent and template microspheres in the PDMS, and then dried to obtain a PDMS template with an ordered spaced microporous structure.

[0059] The scanning electron microscope (SEM) image after demolding from the single - layer microsphere template is as Figure 2As shown in Figure a, it can be seen from this figure that after PDMS can be completely demolded from the single-layer microsphere template, the template microspheres are located in PDMS after demolding. After ultrasonic cleaning with ethanol, the template microspheres in PDMS fall off. The SEM image of the PDMS template with an ordered spaced microporous structure obtained is as Figure 2 shown in Figure b. It can be seen from this figure that the PDMS template has a number of microporous structures arranged in an array. The pore diameter of the microporous structure is about 4 μm and the pore spacing is about 0.3 μm.

[0060] Example 2

[0061] In this example, a preparation method for an ordered spaced microporous structure is provided, and the steps are as follows:

[0062] (1) Coating a release agent on the substrate surface

[0063] Using a quartz wafer as the substrate, the substrate is ultrasonically cleaned in deionized water, acetone, absolute ethanol, and deionized water in sequence for 8 - 20 min, and the cleaned substrate is placed in an oven at 60 °C for drying for 30 min. A fluororesin coating is uniformly coated on the upper surface of the cleaned and dried substrate by spin coating, and the thickness of the formed release agent layer is controlled to be 1.0 ± 0.5 μm to obtain a substrate with a release agent layer.

[0064] (2) Preparing a single-layer microsphere template

[0065] The single-layer microsphere template is prepared by the gas-liquid interface self-assembly method, and the operation is as follows:

[0066] Using monodisperse PS microspheres with a particle size of 4.5 μm as template microspheres, the template microspheres are added to a mixed solution of deionized water and ethanol (the volume ratio of deionized water to ethanol is 1:3), and are fully dispersed to obtain a template microsphere suspension with a template microsphere content of 1 wt%. SDS is dissolved in deionized water to obtain an SDS solution with an SDS concentration of 2 wt%.

[0067] The substrate with a release agent layer is treated in oxygen plasma for 1 min, and then immersed in deionized water in a container with the side of the substrate provided with the release agent layer facing the liquid surface and parallel to the liquid surface. The template microsphere suspension is slowly dripped onto the liquid surface until the liquid surface is covered by a closely packed template microsphere film layer. Then, the SDS solution is gradually dripped into the container until the template microspheres are closely arranged on the liquid surface. Finally, the substrate is slowly taken out of the container. During the taking-out process, the side of the substrate provided with the isolation layer is always kept parallel to the liquid surface, that is, the substrate is used to "fish" the template microsphere film layer located on the liquid surface. The taken-out substrate is left standing with the isolation layer facing up until the deionized water and ethanol are completely volatilized, and a single-layer microsphere template with a single-layer array arrangement of template microspheres on the substrate is obtained.

[0068] (3) Preparation of PDMS template with ordered spaced microporous structure

[0069] The PDMS prepolymer and the curing agent were fully mixed at a mass ratio of 10:1 to obtain a PDMS prepolymer solution. The PDMS prepolymer solution was cast onto the single-layer microspheres of the single-layer microsphere template to form a casting layer, and the thickness of the casting layer was controlled to be 1 mm. The layer was then placed in a vacuum drying oven for vacuum degassing and kept at 80°C for 4 hours to solidify the PDMS prepolymer solution. The solidified PDMS was carefully demolded from the single-layer microsphere template and ultrasonically cleaned in anhydrous ethanol for 4 hours to remove the residual isolation agent and template microspheres in the PDMS, and dried to obtain a PDMS template with an ordered spaced microporous structure.

[0070] The SEM images of the PDMS template with ordered spaced microporous structure prepared in this example at different magnifications are shown in FIG. Figure 3 As shown in Figures a and b, Figure 3 It can be seen that the PDMS template has a number of array-arranged microporous structures, the pore diameter of the microporous structure is about 3.5 μm, and the pore spacing is about 0.3 μm.

[0071] Example 3

[0072] In this embodiment, a method for preparing an ordered spaced microporous structure is provided, and the steps are as follows:

[0073] (1) Coating a release agent on the substrate surface

[0074] A quartz sheet was used as a substrate, and the substrate was ultrasonically cleaned in deionized water, acetone, anhydrous ethanol, and deionized water for 8 to 20 minutes, and the cleaned substrate was placed in a 60°C oven for drying for 30 minutes. A layer of fluororesin coating was evenly coated on the surface of the cleaned and dried substrate by spin coating, and the thickness of the insulating agent layer formed by coating was controlled to be 0.5±0.2μm, to obtain a substrate with an insulating agent layer.

[0075] (2) Preparation of single-layer microsphere template

[0076] The single-layer microsphere template was prepared by air-liquid interface self-assembly method, and the operation was as follows:

[0077] Monodisperse PS microspheres with a particle size of 5 μm were used as template microspheres. The template microspheres were added into a mixture of deionized water and ethanol (the volume ratio of deionized water to ethanol was 1:3) and fully dispersed to obtain a template microsphere suspension with a template microsphere content of 1 wt%. SDS was dissolved in deionized water to obtain an SDS solution with an SDS concentration of 2 wt%.

[0078] The substrate with the isolation agent layer is treated in oxygen plasma for 1 minute, and then immersed in deionized water in a container so that the side of the substrate with the isolation agent layer faces the liquid surface and is parallel to the liquid surface, and the template microsphere suspension is slowly dripped onto the liquid surface until the liquid surface is covered by the tightly packed template microsphere film layer, and then dripped into the container drop by drop until the template microspheres are tightly arranged on the liquid surface. Finally, the substrate is slowly taken out of the container. During the taking-out process, the side of the substrate with the isolation layer is always kept parallel to the liquid surface, that is, the template microsphere film layer on the liquid surface is "salvaged" with the substrate, and the taken-out substrate is left to stand with the isolation layer facing upward until the deionized water and ethanol are completely evaporated, so as to obtain a single-layer microsphere template with the template microspheres arranged in a single-layer array on the substrate.

[0079] (3) Preparation of PDMS template with ordered spaced microporous structure

[0080] The PDMS prepolymer and the curing agent were fully mixed at a mass ratio of 10:1 to obtain a PDMS prepolymer solution. The PDMS prepolymer solution was cast onto the single-layer microspheres of the single-layer microsphere template to form a casting layer, and the thickness of the casting layer was controlled to be 1 mm, and then placed in a vacuum drying oven for vacuum degassing, and kept at 80°C for 4 hours to solidify the PDMS prepolymer solution, and the solidified PDMS was carefully demolded from the single-layer microsphere template and placed in ethyl acetate at 60°C for 4 hours to dissolve and remove the template microspheres of the PDMS, and then washed with anhydrous ethanol and dried to obtain a PDMS template with an ordered spaced microporous structure.

[0081] The SEM image after demoulding from the single-layer microsphere template is as follows Figure 4 As shown in Figures a and b, it can be seen that after PDMS can be completely demolded from the single-layer microsphere template, the template microspheres are located in the PDMS after demolding. After being treated with ethyl acetate, the template microspheres are dissolved and removed by ethyl acetate. The SEM image of the obtained PDMS template with an ordered spaced microporous structure is shown in Figure 4 As shown in Figures c and d, it can be seen that the PDMS template has several array-arranged microporous structures, the pore diameter of the microporous structure is about 3μm, and the pore spacing is about 1.7μm.

[0082] Example 4

[0083] In this embodiment, a method for preparing an ordered spaced microporous structure is provided, and the steps are as follows:

[0084] (1) Coating a release agent on the substrate surface

[0085] Using a quartz wafer as the substrate, the substrate is ultrasonically cleaned in deionized water, acetone, absolute ethanol, and deionized water in sequence for 8 - 20 min, and then the cleaned substrate is placed in an oven at 60 °C for drying for 30 min. A fluororesin coating is uniformly applied on the upper surface of the cleaned and dried substrate by spin coating, and the thickness of the formed isolation layer is controlled to be 0.3 ± 0.1 μm, obtaining a substrate with an isolation layer.

[0086] (2) Preparation of a single - layer microsphere template

[0087] The single - layer microsphere template is prepared by the gas - liquid interface self - assembly method, and the operation is as follows:

[0088] Using monodisperse PS microspheres with a particle size of 5 μm as template microspheres, the template microspheres are added to a mixed solution of deionized water and ethanol (the volume ratio of deionized water to ethanol is 1:3), and dispersed sufficiently to obtain a template microsphere suspension with a template microsphere content of 1 wt%. SDS is dissolved in deionized water to obtain an SDS solution with an SDS concentration of 2 wt%.

[0089] The substrate with the isolation layer is treated in oxygen plasma for 1 min, and then immersed in deionized water in a container with the side of the substrate with the isolation layer facing the liquid surface and parallel to the liquid surface. The template microsphere suspension is slowly dropped onto the liquid surface until the liquid surface is covered by a closely packed template microsphere film layer. Then, the SDS solution is dropped into the container drop by drop until the template microspheres are closely arranged on the liquid surface. Finally, the substrate is slowly taken out of the container. During the taking - out process, the side of the substrate with the isolation layer is always kept parallel to the liquid surface, that is, the substrate is used to "fish" the template microsphere film layer on the liquid surface. The taken - out substrate is left to stand with the isolation layer facing up until the deionized water and ethanol are completely volatilized, obtaining a single - layer microsphere template with the template microspheres arranged in a single - layer array on the substrate.

[0090] (3) Preparation of a PDMS template with an ordered spaced microporous structure

[0091] The PDMS prepolymer and the curing agent are fully mixed according to a mass ratio of 10:1 to obtain a PDMS prepolymer solution. The PDMS prepolymer solution is poured onto the single - layer microspheres of the single - layer microsphere template to form a pouring layer, and the thickness of the pouring layer is controlled to be 1 mm. Then it is placed in a vacuum drying oven for vacuum degassing and kept at 80 °C for 4 h to cure the PDMS prepolymer solution. The cured PDMS is carefully demolded from the single - layer microsphere template and placed in ethyl acetate at 60 °C for heating for 6 h to dissolve and remove the template microspheres in the PDMS. Then it is washed with absolute ethanol and dried to obtain a PDMS template with an ordered spaced microporous structure.

[0092] The SEM image after demolding from the single - layer microsphere template is as Figure 5As shown in Figures a and b, it can be seen from the figure that after PDMS can be completely demolded from the single-layer microsphere template, the template microspheres are located in the PDMS after demolding. After treatment with ethyl acetate, the template microspheres are dissolved and removed by ethyl acetate. The SEM image of the PDMS template with an ordered spaced microporous structure obtained is as Figure 5 shown in Figures c and d. It can be seen from the figure that the PDMS template has a number of microporous structures arranged in an array, and the pore diameter of the microporous structure is about 2.5 μm and the pore spacing is about 3 μm.

[0093] Combined with Examples 1 to 4, it can be known that the method of the present invention can flexibly adjust the size and spacing of the finally obtained microporous structure by adjusting the diameter of the template microspheres and the thickness of the isolation layer. For example, combined with Examples 1, 2 to 4, it can be known that when the particle size of the template microspheres is determined, the pore diameter and pore spacing of the microporous structure can be regulated by adjusting the thickness of the isolation layer.

[0094] Example 5

[0095] In this example, a conductive microsphere array is constructed based on the ordered spaced microporous structure in Example 1, and the operation is as follows:

[0096] Using PS microspheres with a diameter of about 3.25 μm and nickel-plated on the surface as conductive microspheres, a conductive microsphere array is constructed by the friction-assisted microsphere assembly method, that is: placing a small amount of conductive microspheres on the side with the microporous structure of the PDMS template prepared in Example 1, and using a PDMS flexible material in the shape of a cuboid to gently rub the conductive microspheres 5 to 10 times along the same direction on the surface of the PDMS template, and wiping off the excess conductive microspheres, so that the conductive microspheres enter the micropores on the PDMS template to achieve an arrayed arrangement of the conductive microspheres, as Figure 6 shown in Figures a and b. Finally, the arrayed conductive microspheres are transferred to the target substrate using a commercial tape or resin film, that is, a conductive microsphere array is constructed, as Figure 6 shown in Figures c and d.

[0097] Example 6

[0098] In this example, a conductive microsphere array is constructed based on the ordered spaced microporous structure in Example 2, and the operation is as follows:

[0099] Using PS microspheres with a diameter of about 3.25 μm and nickel-plated surfaces as conductive microspheres, a conductive microsphere array was constructed by the friction-assisted microsphere assembly method, that is: a small amount of conductive microspheres were placed on the side with the microporous structure of the PDMS template with an ordered spaced microporous structure prepared in Example 2. A PDMS flexible material in the shape of a cuboid was used to gently rub the conductive microspheres on the surface of the PDMS template in the same direction 5-10 times, and the excess conductive microspheres were wiped off, so that the conductive microspheres entered the micropores on the PDMS template to achieve an array arrangement of the conductive microspheres, as Figure 7 shown in Figures a and b of Figure 7 . Finally, the arrayed conductive microspheres were transferred to the target substrate using commercial tape or resin film, that is, a conductive microsphere array was constructed, as

[0100] Example 7

[0101] In this example, a conductive microsphere array was constructed based on the ordered spaced microporous structure in Example 3. The operation is as follows:

[0102] Using PS microspheres with a diameter of about 3.25 μm and nickel-plated surfaces as conductive microspheres, a conductive microsphere array was constructed by the friction-assisted microsphere assembly method, that is: a small amount of conductive microspheres were placed on the side with the microporous structure of the PDMS template with an ordered spaced microporous structure prepared in Example 3. A PDMS flexible material in the shape of a cuboid was used to gently rub the conductive microspheres on the surface of the PDMS template in the same direction 5-10 times, and the excess conductive microspheres were wiped off, so that the conductive microspheres entered the micropores on the PDMS template to achieve an array arrangement of the conductive microspheres. Finally, the arrayed conductive microspheres were transferred to the target substrate using commercial tape or resin film, that is, a conductive microsphere array was constructed, as Figure 8 shown in Figures a and b of

[0103] Example 8

[0104] In this example, a preparation method for an ordered spaced microporous structure is provided. The steps are as follows:

[0105] (1) Coating a release agent on the substrate surface

[0106] Using a quartz wafer as the substrate, the substrate was ultrasonically cleaned in deionized water, acetone, absolute ethanol, and deionized water for 8-20 min in sequence, and the cleaned substrate was placed in an oven at 60 °C for 30 min to dry. A layer of fluororesin coating was uniformly coated on the upper surface of the cleaned and dried substrate by spin coating, and the thickness of the formed release agent layer was controlled to be 1.5 ± 0.5 μm to obtain a substrate with a release agent layer.

[0107] (2) Preparing a monolayer microsphere template

[0108] A monolayer microsphere template was prepared by convective self-assembly method, and the operation is as follows:

[0109] Using monodisperse PS microspheres with a particle size of 5 μm as template microspheres, the template microspheres were added to a mixed solution of deionized water and ethanol (the volume ratio of deionized water to ethanol is 1:3), and fully dispersed to obtain a template microsphere suspension with a template microsphere content of 0.5 wt%.

[0110] The substrate with an isolation layer was treated in oxygen plasma for 1 min, and then placed on a hot stage at 100 °C with the side having the isolation layer facing up. 0.3 mL of the template microsphere suspension was dropped onto the isolation layer of the substrate, and the template microsphere suspension was slowly scraped along the same direction by a scraping method. The moving speed of the scraper during scraping was controlled at 5.0 μm / s. During the evaporation of the solvent in the template microsphere suspension, forces including capillary force and surface tension induced the template microspheres to be uniformly arranged along the scraping direction. After the deionized water and ethanol in the template microsphere suspension were completely evaporated, a monolayer microsphere template with a monolayer array arrangement of template microspheres on the substrate was obtained.

[0111] (3) Preparation of a PDMS template with an ordered spaced microporous structure

[0112] The PDMS prepolymer and the curing agent were fully mixed at a mass ratio of 10:1 to obtain a PDMS prepolymer solution. The PDMS prepolymer solution was poured onto the monolayer microspheres of the monolayer microsphere template to form a pouring layer, and the thickness of the pouring layer was controlled to be 1 mm. Then it was placed in a vacuum drying oven for vacuum degassing, and kept at 80 °C for 4 h to cure the PDMS prepolymer solution. The cured PDMS was carefully demolded from the monolayer microsphere template and placed in absolute ethanol for ultrasonic cleaning for 4 h to remove the residual isolation agent and template microspheres in the PDMS, and then dried to obtain a PDMS template with an ordered spaced microporous structure.

[0113] Example 9

[0114] In this example, a preparation method for an ordered spaced microporous structure is provided, and the steps are as follows:

[0115] (1) Coating an isolation agent on the substrate surface

[0116] Using a quartz wafer as the substrate, the substrate was ultrasonically cleaned in deionized water, acetone, absolute ethanol, and deionized water for 8 - 20 min in sequence, and the cleaned substrate was placed in an oven at 60 °C for drying for 30 min. A layer of fluororesin coating was uniformly coated on the upper surface of the cleaned and dried substrate by a spin coating method, and the thickness of the formed isolation layer was controlled to be 1.2 ± 0.5 μm to obtain a substrate with an isolation layer.

[0117] (2) Preparation of a monolayer microsphere template

[0118] A single-layer microsphere template was prepared by convective self-assembly method, and the operation is as follows:

[0119] Using monodisperse PS microspheres with a particle size of 4 μm as template microspheres, the template microspheres were added to absolute ethanol and fully dispersed to obtain a template microsphere suspension with a template microsphere content of 0.1 wt%.

[0120] The substrate with an isolation layer was treated in oxygen plasma for 1 min, and then placed on a hot stage at 60 °C with the side having the isolation layer facing up. 0.2 mL of the template microsphere suspension was dropped onto the isolation layer of the substrate, and the template microsphere suspension was slowly scraped in the same direction by means of blade coating. The moving speed of the blade during blade coating was controlled at 1 μm / s. During the evaporation of the solvent in the template microsphere suspension, forces including capillary force and surface tension induced the template microspheres to be uniformly arranged along the scraping direction. After the absolute ethanol in the template microsphere suspension was completely evaporated, a single-layer microsphere template with a single-layer array arrangement of template microspheres on the substrate was obtained.

[0121] (3) Preparation of a PDMS template with an ordered spaced microporous structure

[0122] The PDMS prepolymer and the curing agent were fully mixed at a mass ratio of 10:1 to obtain a PDMS prepolymer solution. The PDMS prepolymer solution was poured onto the single-layer microspheres of the single-layer microsphere template to form a pouring layer, and the thickness of the pouring layer was controlled at 1 mm. Then it was placed in a vacuum drying oven for vacuum degassing and maintained at 80 °C for 4 h to cure the PDMS prepolymer solution. The cured PDMS was carefully demolded from the single-layer microsphere template and placed in absolute ethanol for ultrasonic cleaning for 4 h to remove the residual isolation agent and template microspheres in the PDMS, and then dried to obtain a PDMS template with an ordered spaced microporous structure.

Claims

1. A method for preparing an ordered spaced microporous structure, characterized in that: The following steps are involved: (1) coating a layer of release agent on a cleaned and dried substrate to obtain a substrate with a release agent layer; the release agent is fatty acid, paraffin oil, vaseline, silicone oil, polyvinyl alcohol or fluororesin coating; (2) constructing a monodisperse template microsphere arranged in a monolayer array on the release agent layer of the substrate to obtain a monolayer microsphere template; the thickness of the release layer is 4% to 50% of the diameter of the template microsphere; (3) pouring a polymer precursor on the template microspheres of the single-layer microsphere template to form a pouring layer, curing the polymer precursor to form a polymer, demolding, and removing the isolation agent and template microspheres attached to the cured polymer to obtain a polymer template with an ordered spaced microporous structure.

2. The method for preparing the ordered spaced microporous structure according to claim 1, characterized in that: In step (2), a single-layer microsphere template is prepared by a gas-liquid interface self-assembly method or a convection self-assembly method.

3. The method for preparing the ordered spaced microporous structure according to claim 2, characterized in that: The operation of preparing a single-layer microsphere template by air-liquid interface self-assembly method in step (2) is as follows: The substrate with the release agent layer is treated with oxygen plasma, and then immersed in an aqueous solvent in a container so that the side of the substrate provided with the release agent layer faces the liquid surface, and a template microsphere suspension is slowly dripped onto the liquid surface until the liquid surface is covered by a tightly packed template microsphere film layer, and then a water-soluble surfactant solution is dripped into the container so that the template microspheres are tightly arranged on the liquid surface, and then the substrate is taken out of the container. During the process of taking out the substrate, the side of the substrate provided with the release layer is always kept parallel to the liquid surface, and after the solvent on the substrate to be taken out is completely volatilized, a single-layer microsphere template with the template microspheres arranged in a single-layer array on the substrate is obtained; the aqueous solvent is water, an aqueous solution of a water-soluble salt, or an aqueous solution of a water-soluble polymer, the concentration of the aqueous solution of the water-soluble salt is 2wt% to 10wt%, and the concentration of the aqueous solution of the water-soluble polymer is 2wt% to 10wt%.

4. The method for preparing the ordered spaced microporous structure according to claim 3, characterized in that: In the template microsphere suspension, the concentration of the template microspheres is 1wt% to 10wt%, the solvent used to prepare the template microsphere suspension is water, an organic solvent or a mixed solution of water and an organic solvent; the concentration of the water-soluble surfactant solution is 2wt% to 8wt%.

5. The method for preparing the ordered spaced microporous structure according to claim 2, characterized in that: The operation of preparing a single-layer microsphere template by convection self-assembly in step (2) is as follows: The substrate with the release agent layer is treated with oxygen plasma and then placed on a hot plate at 60-100°C with the side of the substrate provided with the release agent layer facing upward, a template microsphere suspension is dripped onto the release agent layer, and the template microsphere suspension is scraped along the same direction by means of scraping. During the process of thermal evaporation of the solvent of the template microsphere suspension, forces including capillary force and surface tension induce the template microspheres to be evenly arranged along the scraping direction. After the solvent of the template microsphere suspension is completely evaporated, a single-layer microsphere template in which the template microspheres are arranged in a single-layer array on the substrate is obtained.

6. The method for preparing the ordered spaced microporous structure according to claim 5, characterized in that: In the template microsphere suspension, the concentration of the template microspheres is preferably 0.1wt% to 0.5wt%, and the solvent used to prepare the template microsphere suspension is water, an organic solvent, or a mixed solution of water and an organic solvent.

7. The method for preparing the ordered spaced microporous structure according to any one of claims 1 to 6, characterized in that: The template microspheres in step (2) are inorganic microspheres or organic microspheres. When the template microspheres in step (2) are organic microspheres, the material of the template microspheres is different from the material of the polymer obtained after the casting layer is solidified in step (3).

8. The method for preparing the ordered spaced microporous structure according to any one of claims 1 to 6, characterized in that: The thickness of the casting layer is at least 10 times the diameter of the template microspheres.

9. A method for preparing a microsphere array, characterized in that: The conductive microspheres are filled into the micropores of the polymer template having an orderly spaced micropore structure prepared by the method described in any one of claims 1 to 8, the conductive microspheres are filled into the micropores of the polymer template having an orderly spaced micropore structure to achieve an arrayed arrangement of the conductive microspheres, and the arrayed conductive microspheres are transferred to a target substrate to obtain a microsphere array.

10. The method for preparing a microsphere array according to claim 9, characterized in that: The particle size of the conductive microspheres is controlled to be 0.7 to 1.5 times the diameter of the micropores on the polymer template having an orderly spaced micropore structure.

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