Method for preparing ordered spaced microcellular structure and microsphere array

Abstract

The present application provides a preparation method of ordered interval microporous structure, which comprises the following steps: firstly, coating a release agent on a substrate to obtain a substrate with a release agent layer; then, constructing a single-layer array distribution of monodisperse template microspheres on the release agent layer of the substrate to obtain a single-layer microsphere template; then, pouring a polymer precursor liquid on the template microspheres of the single-layer microsphere template and solidifying; then, demolding; and then, removing the release agent and the template microspheres adhered in the obtained solidified polymer, so as to obtain a polymer template with ordered interval microporous structure. Based on the ordered interval microporous structure, the present application further provides a preparation method of microsphere array. The present application can solve the problems of the existing processing method of high-size-precision ordered interval microporous structure, such as dependence on expensive equipment, harsh preparation conditions and complex process, and realizes simple and efficient preparation of ordered interval microporous structure and microsphere array.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of microstructure manufacturing and processing technology for electronic chips, chemical industry, chemistry and the like, and relates to a preparation method of ordered interval microporous structure and microsphere array. BACKGROUND

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

[0003] At present, the method widely used for constructing equal-interval microsphere array is template-assisted assembly method, that is, using a template with specific ordered interval microporous structure to assist the filling of microspheres. These microporous structures are often constructed by reactive ion etching, laser etching, electron beam etching, nanoimprint and soft lithography technology. Typically, the reactive ion etching technology is to use a radio frequency power source to excite hydrogen fluoride or oxygen to generate plasma in a vacuum environment, and to use the high-speed vertical or inclined bombardment of the plasma on the surface of the substrate to cause chemical reaction and generate volatile products, which are removed by vacuum system, that is, to form microporous structure on the substrate; the electron beam etching is to form a pattern on a silicon wafer by precisely controlling the acceleration voltage, beam current and scanning speed of the electron beam system, and then removing the residual by chemical cleaning, heat treatment or ion bombardment, etc., to finally form a fine microporous structure; the soft lithography technology mainly prepares a patterned template through spin coating, pre-baking, ultraviolet exposure and development steps, and the operation process is relatively simple, but still needs to rely on expensive instruments, and the precision is slightly insufficient, which is usually suitable for the construction of microporous structure with a scale of several hundred microns. As can be seen from the above, the traditional high-precision ordered interval microporous structure processing technology often relies on expensive equipment, harsh preparation conditions and complex process flow, which significantly limits its further industrial application. Therefore, it is still necessary to develop a simple and efficient ordered interval microporous structure preparation technology. SUMMARY

[0004] The present application provides a preparation method of an ordered spaced microporous structure and a microsphere array, so as to realize simple and efficient preparation of the ordered spaced microporous structure and the microsphere array.

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

[0006] The preparation method of the ordered spaced microporous structure comprises the following steps:

[0007] (1) coating an isolation agent layer on a clean and dry substrate to obtain a substrate with an isolation agent layer; the isolation agent is a fatty acid, paraffin oil, vaseline, silicone oil, polyvinyl alcohol or fluororesin paint;

[0008] (2) constructing a monolayer array of monodisperse template microspheres on the isolation agent layer of the substrate to obtain a monolayer microsphere template; the thickness of the isolation layer is 4% to 50% of the diameter of the template microspheres;

[0009] (3) pouring a polymer precursor solution on the template microspheres of the monolayer microsphere template to form a pouring layer, solidifying the polymer precursor solution to form a polymer, demolding, removing the isolation agent and the template microspheres attached to the solidified polymer to obtain a polymer template with an ordered spaced microporous structure.

[0010] In step (2) of the technical scheme of the preparation method of the ordered spaced microporous structure, the monolayer microsphere template is prepared by a method including a gas-liquid interface self-assembly method, a convection self-assembly method and the like.

[0011] In step (2) of the technical scheme of the preparation method of the ordered spaced microporous structure, the operation of preparing the monolayer microsphere template by the gas-liquid interface self-assembly method is as follows:

[0012] The substrate with the isolation agent layer is subjected to oxygen plasma treatment, and then immersed in an aqueous solvent in a container with the side provided with the isolation agent layer facing the liquid surface. Template microspheres are slowly added dropwise onto the liquid surface until the liquid surface is covered with a tightly packed template microsphere film layer. Then, a water-soluble surfactant solution is added dropwise into the container to make the template microspheres tightly arranged on the liquid surface. Then, the substrate is taken out of the container, and the side of the substrate provided with the isolation layer is kept parallel to the liquid surface during the process of taking out the substrate. After the solvent on the taken-out substrate is completely volatilized, a monolayer microsphere template with the template microspheres arranged in a monolayer array on the substrate is obtained.

[0013] In step (2) of the technical scheme of the method for preparing the ordered interval microporous structure, when the single-layer microsphere template is prepared 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 2wt%-10wt%, the water-soluble salt can be sodium chloride, potassium chloride or the like, the concentration of the aqueous solution of the water-soluble polymer is 2wt%-10wt%, and the water-soluble polymer can be polyvinyl alcohol, polyurethane or the like. When the particle size of the template microspheres is large (for example, greater than 10 μm) or the density is large, the template microspheres tend to sink to the bottom of the container due to their large gravity, and it is not easy to form a uniform template microsphere film layer on the liquid surface. At this time, the aqueous solution of the water-soluble salt or the aqueous solution of the water-soluble polymer can be used as the aqueous solvent. Using the aqueous solution of the water-soluble salt as the aqueous solvent can increase the density of the aqueous solvent in the container, and using the aqueous solution of the 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 scheme of the method for preparing the ordered interval microporous structure, when the single-layer microsphere template is prepared by the gas-liquid interface self-assembly method, the concentration of the template microspheres in the template microsphere suspension is preferably 1wt%-10wt%. The solvent used for preparing 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 or the like. When the solvent used for preparing the template microsphere suspension contains an organic solvent, the organic solvent can exert an upward force on the template microspheres on the liquid surface when it volatilizes from the liquid surface, thereby helping to prevent the template microspheres from sinking.

[0015] In step (2) of the technical scheme of the method for preparing the ordered interval microporous structure, when the single-layer microsphere template is prepared by the gas-liquid interface self-assembly method, the concentration of the aqueous surfactant solution is preferably 2wt%-8wt%, and the surfactant can be sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, potassium dodecyl sulfate or the like.

[0016] In step (2) of the technical scheme of the method for preparing the ordered interval microporous structure, when the single-layer microsphere template is prepared by the gas-liquid interface self-assembly method, the aqueous surfactant is added dropwise into the container, and the addition is stopped when the template microspheres are closely arranged on the liquid surface.

[0017] In step (2) of the technical scheme of the method for preparing the ordered interval microporous structure, the operation of preparing the single-layer microsphere template by the convection self-assembly method is as follows:

[0018] The substrate with the release agent layer is subjected to oxygen plasma treatment, and then is placed on a hot stage at 60-100℃ with the side provided with the release agent layer facing upward. The template microsphere suspension is dropped on the release agent layer of the substrate, and is scraped in the same direction by way of blade coating. During the evaporation of the solvent of the template microsphere suspension, the forces including capillary force and surface tension induce the template microspheres to be uniformly arranged along the direction of blade coating. 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 scheme of the method for preparing the ordered spaced microporous structure, when the monolayer microsphere template is prepared by the convective self-assembly method, the moving speed of the blade during the blade coating is preferably controlled to be a constant speed of 0.1-5.0 μm / s.

[0020] In step (2) of the technical scheme of the method for preparing the ordered spaced microporous structure, when the monolayer microsphere template is prepared by the convective self-assembly method, the concentration of the template microspheres in the template microsphere suspension is preferably 0.1wt%-0.5wt%. The solvent used for preparing 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 or the like.

[0021] In the technical scheme of the method for preparing the ordered spaced microporous structure, the thickness of the release layer is 4%-50% of the diameter of the template microspheres.

[0022] In the technical scheme of the method for preparing the 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 the layer to be cast is solidified in step (3). The inorganic microspheres can be calcium carbonate (CaCO3) microspheres, metal microspheres, metal oxide microspheres or silicon dioxide (SiO2) microspheres, and the organic microspheres can be polystyrene (PS) microspheres or polymethyl methacrylate (PMMA) microspheres, but the template microspheres are not limited to the specific microspheres listed above.

[0023] In step (3) of the technical scheme of the method for preparing the ordered spaced microporous structure, the template microspheres attached to the polymer obtained after solidification can be removed by mechanical means such as ultrasonic treatment, water flushing or gas blowing, or can be removed by selective dissolution with a solvent. When the template microspheres are selectively dissolved with a solvent, the solvent used for the selective dissolution can dissolve the template microspheres but cannot dissolve the polymer formed after solidification.

[0024] In the above-mentioned method for preparing ordered spaced microporous structures, the thickness of the casting layer affects the mechanical strength of the polymer template with ordered spaced microporous structures. In order to ensure the integrity and stability of the polymer template with ordered spaced microporous structures 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 above-mentioned method for preparing ordered spaced microporous structures, 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 above-mentioned method for preparing ordered spaced microporous structures, a release agent is coated on the planar region of the substrate to form a release agent layer.

[0027] In step (1) of the above-mentioned method for preparing ordered spaced microporous structures, the substrate can be a quartz substrate or a silicon substrate.

[0028] This invention experimentally demonstrates that, based on a fixed template microsphere size, the micropore size and spacing of the final ordered, spaced microporous structure can be adjusted by changing the thickness of the isolation layer. Figure 1 As shown, the encapsulation depth of the template microspheres 3 by the release agent layer 2 on the substrate 1 changes with the thickness of the release agent layer 2. After the polymer precursor liquid is poured to form a casting layer and then cured, the encapsulation depth of the template microspheres by the cured polymer 4 also varies. Therefore, after removing the template microspheres, the size and spacing of the micropores in the resulting polymer template with an ordered spaced microporous structure also change. This allows for convenient and flexible control of the micropore size and spacing of the ordered spaced microporous structure. Figures (a), (b), and (c) illustrate the effect of the change in the thickness of the release agent layer on the micropore size and spacing. Of course, in the above technical solution of the present invention, the size and spacing of the micropores 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 ordered spaced microporous structure prepared by the above-mentioned method for preparing ordered spaced microporous structure, the present invention also provides a method for preparing microsphere array: filling conductive microspheres into the micropores of the polymer template with ordered spaced microporous structure to achieve arrayed arrangement of conductive microspheres, and transferring the arrayed conductive microspheres onto a target substrate to obtain a microsphere array.

[0030] In the technical scheme of the preparation method of the microsphere array, in order to realize the array arrangement of the conductive microspheres, it is necessary to ensure that one conductive microsphere is filled in each microhole, and in order to ensure that one conductive microsphere is filled in each microhole, it is necessary to control the particle size of the conductive microspheres to be 0.7-1.5 times the diameter of the microholes on the polymer template with the ordered and spaced microhole structure.

[0031] In the technical scheme of the 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 microhole structure of the polymer template with the ordered and spaced microhole structure, and then a flexible block material (such as rubber, elastomer, polydimethylsiloxane, etc.) is gently rubbed several times (such as 5-10 times) along the same direction, so that the conductive microspheres enter the microholes on the polymer template to realize the array arrangement of the conductive microspheres in the polymer template, and finally the array-arranged conductive microspheres are transferred to a target substrate by using a commercial adhesive tape or a resin adhesive film, and the microsphere array is obtained.

[0032] In the technical scheme of the preparation method of the microsphere array, the conductive microspheres are the conductive microspheres used in the preparation of anisotropic conductive films in the prior art, such as gold-plated polystyrene microspheres, silver-plated polystyrene microspheres, nickel-plated polystyrene microspheres, nickel-plated polyurethane microspheres, copper-plated polystyrene microspheres, and cobalt-plated polystyrene microspheres.

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

[0034] The ordered and spaced microhole structure prepared by the technical scheme of the preparation method of the ordered and spaced microhole structure can be used in the preparation of a microsphere array, and can also be applied to super-hydrophobic surfaces, optical devices, biological detection, chemical reactions, etc. The roughness of the microhole structure may affect these applications. According to the actual application requirements, the roughness of the microhole structure can be adjusted by adjusting the surface roughness of the template microspheres, so as to adjust the properties of the surface and better meet the application requirements.

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

[0036] 1. The present application provides a method for preparing an ordered interval microporous structure, which comprises the following steps: firstly, coating an isolating agent on a clean and dry substrate to obtain a substrate with an isolating agent layer; then, constructing a monolayer array of monodisperse template microspheres on the isolating agent layer of the substrate to obtain a monolayer microsphere template; then, pouring a polymer precursor liquid on the template microspheres of the monolayer microsphere template to form a pouring layer; then, solidifying the polymer precursor liquid to form a polymer; then, demolding; and then, removing the isolating agent and the template microspheres attached to the solidified polymer to obtain a polymer template with an ordered interval microporous structure. Compared with the prior art methods for preparing an ordered interval microporous structure with high dimensional precision by means of chemical etching, laser etching, electron beam etching, nanoimprinting and soft lithography, the method of the present application has the advantages of simple operation, high dimensional precision, large-area order and no need to rely on complex equipment, and has the characteristics of good process controllability and easy realization of large-scale production. The present application provides a new idea for controllable preparation of an ordered interval microporous structure with high dimensional precision.

[0037] 2. The method of the present application can flexibly regulate the micropore size and interval of the ordered interval microporous structure by adjusting the particle size of the template microspheres and the thickness of the isolating agent layer, and has the advantage of convenient and flexible regulation of the micropore size and interval compared with the prior art.

[0038] 3. The ordered interval microporous structure prepared by the method of the present application can be used for the construction of a microsphere array, and provides a high-precision template for the array arrangement of conductive microspheres, based on which the present application further provides a method for preparing a microsphere array, which comprises the following steps: filling conductive microspheres into the micropores of the polymer template with an ordered interval microporous structure to realize the array arrangement of the conductive microspheres; and then, transferring the arrayed conductive microspheres to a target substrate, thereby realizing the convenient and efficient construction of a microsphere array.

[0039] 4. The ordered interval microporous structure prepared by the method of the present application can also be applied to superhydrophobic surfaces, optical devices, biological detection, chemical reactions and the like. The roughness of the microporous structure may affect these applications. According to the actual application requirements, the roughness of the microporous structure can be regulated by regulating the surface roughness of the template microspheres, and then the properties of the surface can be regulated to better meet the application requirements. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a flowchart of the method for preparing an ordered interval microporous structure and a schematic diagram for regulating the size and interval of the microporous structure, in which, 1 is a substrate, 2 is an isolating agent layer, 3 is a template microsphere, and 4 is a solidified polymer.

[0041] Figure 2 The a graph of is a SEM graph of Example 1 after demolding from a monolayer microsphere template, Figure 2Figure 2b is a SEM image of the PDMS template with ordered and spaced microporous structure prepared in Example 1.

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

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

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

[0045] Figure 6 Figure 6a and 6b are SEM images of the PDMS template after arraying and arranging the conductive microspheres in the microporous structure in Example 5, Figure 6 Figure 6c and 6d are SEM images of the equidistant microsphere array prepared in Example 5.

[0046] Figure 7 Figure 7a and 7b are SEM images of the PDMS template after arraying and arranging the conductive microspheres in the microporous structure in Example 6, Figure 7 Figure 7c and 7d are SEM images of the equidistant microsphere array prepared in Example 6.

[0047] Figure 8 Figure 8a and 8b are SEM images of the equidistant microsphere array prepared in Example 7. DETAILED DESCRIPTION

[0048] The preparation method of the ordered and spaced microporous structure and the microsphere array provided by the present application is further described by the following examples. It is necessary to point out that the following examples are only used to further illustrate the present application and cannot be understood as a limitation to the protection scope of the present application. The skilled in the art can make some non-essential improvements and adjustments to the specific implementation of the present application according to the above description, which still belongs to the protection scope of the present application.

[0049] Example 1

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

[0051] (1) Coating the spacer on the surface of the substrate

[0052] The quartz wafer was used as a substrate, and the substrate was sequentially cleaned in deionized water, acetone, anhydrous ethanol, and deionized water for 8-20 min. The cleaned and dried substrate was placed in an oven at 60°C for 30 min. A layer of fluororesin coating was uniformly coated on the surface of the cleaned and dried substrate by spin coating. The thickness of the formed release agent layer was controlled to be 1.5±0.5 μm, and a substrate with a release agent layer was obtained.

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

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

[0055] Monodisperse polystyrene (PS) microspheres with a particle size of 5 μm were used as template microspheres. The template microspheres were added to a mixture of deionized water and ethanol (the volume ratio of deionized water to ethanol was 1:3) and 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 a concentration of 2 wt%.

[0056] The substrate with a release agent layer was treated in an oxygen plasma for 1 min, and then immersed in deionized water in a container with the side provided with the release agent layer facing and parallel to the liquid surface. The template microsphere suspension was slowly added to the liquid surface until the liquid surface was covered with a tightly packed template microsphere film layer. Then, the SDS solution was added dropwise to the container until the template microspheres were tightly arranged on the liquid surface. Finally, the substrate was slowly taken out of the container, and the side provided with the release layer was kept parallel to the liquid surface during the taking-out process, i.e., the substrate was used to “fishing” the template microsphere film layer on the liquid surface. The taken-out substrate was placed with the release layer facing upwards until the deionized water and ethanol were completely volatilized, and a single-layer microsphere template with the template microspheres arranged in a single layer on the substrate was obtained.

[0057] (3) Preparation of a polydimethylsiloxane (PDMS) template with an ordered and spaced micro-pore structure

[0058] The PDMS prepolymer and the curing agent were thoroughly mixed in a mass ratio of 10:1 to obtain a PDMS pre-polymer solution. The PDMS pre-polymer 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 to be 1 mm. Then, the pouring layer was placed in a vacuum drying box for vacuum degassing, and kept at 80°C for 4 h to cure the PDMS pre-polymer solution. The cured PDMS was carefully demolded from the single-layer microsphere template and ultrasonically cleaned in anhydrous ethanol for 4 h to remove the residual release agent and template microspheres in the PDMS. After drying, a PDMS template with an ordered and spaced micro-pore structure was obtained.

[0059] The scanning electron microscope (SEM) image of the PDMS template after demolding from the single-layer microsphere template is shown in FIG. 2. Figure 2Figure a of the drawing shows that the PDMS can be completely demolded from the single-layer microsphere template, and the microspheres on the template are located in the PDMS. After the microspheres on the template are removed by ultrasonic cleaning with ethanol, the SEM image of the PDMS template with ordered and spaced micro-porous structure is shown in Figure b of the drawing. Figure 2 Figure b of the drawing shows that the PDMS template has a plurality of arrayed micro-porous structures, the pore diameter of the micro-porous structure is about 4 μm, and the pore spacing is about 0.3 μm.

[0060] Example 2

[0061] In this embodiment, a method for preparing an ordered and spaced micro-porous structure is provided, and the steps are as follows:

[0062] (1) Coating an isolation agent on the surface of a substrate

[0063] Quartz is used as a substrate, and the substrate is sequentially ultrasonically cleaned in deionized water, acetone, anhydrous ethanol, and deionized water for 8-20 min. The cleaned and dried substrate is placed in an oven at 60°C for drying for 30 min. A layer of fluororesin coating is uniformly coated on the surface of the cleaned and dried substrate by spin coating, and the thickness of the formed isolation agent layer is controlled to be 1.0±0.5 μm, thereby obtaining a substrate with an isolation agent layer.

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

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

[0066] Monodisperse PS microspheres with a particle size of 4.5 μm are used as template microspheres, and the template microspheres are added into a mixture of deionized water and ethanol (the volume ratio of deionized water to ethanol is 1:3) to be fully dispersed, thereby obtaining 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 the isolation agent layer is treated in oxygen plasma for 1 min, and then the substrate is immersed in deionized water in a container such that the side of the substrate provided with the isolation agent layer faces and is parallel to the liquid surface. The template microsphere suspension is slowly added dropwise onto the liquid surface until the liquid surface is covered by a tightly packed template microsphere film layer. Then, the SDS solution is added dropwise into the container until the template microspheres are tightly arranged on the liquid surface. Finally, the substrate is slowly taken out of the container, and the side of the substrate provided with the isolation layer is kept parallel to the liquid surface during the taking-out process, i.e., the substrate is used to “fishing” the template microsphere film layer on the liquid surface. The taken-out substrate is placed in the direction with the isolation layer upward until the deionized water and ethanol are completely volatilized, thereby obtaining a single-layer microsphere template in which the template microspheres are arrayed in a single layer on the substrate.

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

[0069] PDMS prepolymer and curing agent were thoroughly mixed at a mass ratio of 10:1 to obtain PDMS prepolymer solution. The PDMS prepolymer solution was poured onto the monolayer microspheres of a monolayer microsphere template to form a casting layer, with the thickness of the casting layer controlled at 1 mm. Then, it was placed in a vacuum drying oven for vacuum degassing and kept at 80°C for 4 hours to cure the PDMS prepolymer solution. The cured PDMS was carefully demolded from the monolayer microsphere template and ultrasonically cleaned in anhydrous ethanol for 4 hours to remove residual release agent and template microspheres from the PDMS. After drying, a PDMS template with an ordered spaced microporous structure was obtained.

[0070] SEM images of the PDMS template with ordered spaced microporous structure prepared in this embodiment at different magnifications are shown below. Figure 3 As shown in Figures a and b, by Figure 3 It can be seen that the PDMS template has several arrayed microporous structures with a pore diameter of about 3.5 μm and a pore spacing of about 0.3 μm.

[0071] Example 3

[0072] In this embodiment, a method for preparing an ordered spaced microporous structure is provided, comprising the following steps:

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

[0074] Using a quartz sheet as a substrate, the substrate was ultrasonically cleaned sequentially in deionized water, acetone, anhydrous ethanol, and deionized water for 8–20 min. The cleaned substrate was then dried in an oven at 60°C for 30 min. A fluoropolymer coating was uniformly coated onto the cleaned and dried substrate surface using a spin-coating method, controlling the thickness of the resulting release agent layer to be 0.5 ± 0.2 μm, thus obtaining a substrate with a release agent layer.

[0075] (2) Preparation of monolayer microsphere template

[0076] Monolayer microsphere templates were prepared using a gas-liquid interface self-assembly method, as follows:

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

[0078] The substrate with the release agent layer is treated in an 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 and parallel to the liquid surface, and the template microsphere suspension is slowly added onto the liquid surface until the liquid surface is covered with a closely packed template microsphere film layer, then the template microspheres are added drop by drop into the container until the template microspheres are closely arranged on the liquid surface, and finally, the substrate is slowly taken out of the container, and during the taking-out process, the side of the substrate provided with the release layer is kept parallel to the liquid surface, that is, the template microsphere film layer on the liquid surface is "fished" by the substrate, and the taken-out substrate is placed with the release layer facing up until the deionized water and ethanol are completely volatilized, that is, a monolayer microsphere template with the template microspheres arranged in a monolayer array on the substrate is obtained.

[0079] (3) Preparation of a PDMS template with an ordered and spaced micro-pore structure

[0080] The PDMS prepolymer and the curing agent are thoroughly mixed in a mass ratio of 10:1 to obtain a PDMS prepolymer solution. The PDMS prepolymer solution is poured onto the monolayer microspheres of the monolayer microsphere template to form a pouring layer, the thickness of the pouring layer is controlled to be 1 mm, and then the pouring layer is placed in a vacuum drying box 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 monolayer microsphere template and heated in ethyl acetate at 60°C for 4 h 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 and spaced micro-pore structure.

[0081] The SEM image of the demolded monolayer microsphere template is shown in Figs. a and b of Figure 4 From the figures, it can be seen that after the PDMS is completely demolded from the monolayer microsphere template, the template microspheres are located in the PDMS, and after treatment with ethyl acetate, the template microspheres are dissolved and removed by the ethyl acetate, and the SEM image of the obtained PDMS template with an ordered and spaced micro-pore structure is shown in Figs. c and d of Figure 4 From the figures, it can be seen that the PDMS template has a plurality of arrayed micro-pore structures, the pore diameter of the micro-pore structure is about 3 μm, and the pore spacing is about 1.7 μm.

[0082] Example 4

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

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

[0085] The quartz wafer was used as a substrate, and the substrate was sequentially cleaned in deionized water, acetone, anhydrous ethanol, and deionized water for 8-20 min. The cleaned and dried substrate was placed in an oven at 60°C for 30 min. A layer of fluororesin coating was uniformly coated on the surface of the cleaned and dried substrate by spin coating. The thickness of the release agent layer formed by coating was controlled to be 0.3±0.1 μm, and a substrate with a release agent layer was obtained.

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

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

[0088] Monodisperse PS microspheres with a particle size of 5 μm were used as template microspheres. The template microspheres were added to a mixture of deionized water and ethanol (volume ratio of deionized water to ethanol was 1:3) and 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 a concentration of 2 wt%.

[0089] The substrate with a release agent layer was treated in an oxygen plasma for 1 min, and then immersed in deionized water in a container with the side provided with the release agent layer facing and parallel to the liquid surface. The template microsphere suspension was slowly added to the liquid surface until the liquid surface was covered with a tightly packed template microsphere film layer. Then, the SDS solution was added dropwise to the container until the template microspheres were tightly arranged on the liquid surface. Finally, the substrate was slowly taken out of the container, and the side provided with the release layer was kept parallel to the liquid surface during the taking-out process, i.e., the substrate was used to "fish" the template microsphere film layer on the liquid surface. The taken-out substrate was placed with the release layer facing upwards until the deionized water and ethanol were completely evaporated, and a single-layer microsphere template with a single-layer array of template microspheres on the substrate was obtained.

[0090] (3) Preparation of a PDMS template with an ordered and spaced micro-pore structure

[0091] The PDMS prepolymer and the curing agent were thoroughly mixed in a mass ratio of 10:1 to obtain a PDMS pre-polymer solution. The PDMS pre-polymer 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 to be 1 mm. Then, the pouring layer was placed in a vacuum drying box for vacuum degassing, and kept at 80°C for 4 h to cure the PDMS pre-polymer solution. The cured PDMS was carefully demolded from the single-layer microsphere template and placed in ethyl acetate at 60°C for 6 h to dissolve and remove the template microspheres in the PDMS. Then, the PDMS was washed with anhydrous ethanol and dried to obtain a PDMS template with an ordered and spaced micro-pore structure.

[0092] The SEM image of the PDMS template after demolding from the single-layer microsphere template is shown in FIG. 2. Figure 5As shown in the a and b of FIG. 1, it can be seen from the figures that the PDMS can be completely demolded from the single-layer microsphere template, and the microspheres on the template are located in the PDMS, and after treatment with ethyl acetate, the microspheres on the template are dissolved and removed by ethyl acetate, and the SEM image of the PDMS template with ordered and spaced micro-pore structure obtained is as shown in the c and d of FIG. 1. Figure 5 As shown in the c and d of FIG. 1, it can be seen from the figures that the PDMS template has a plurality of arrayed micro-pore structures, the pore diameter of the micro-pore structure is about 2.5 μm, and the pore spacing is about 3 μm.

[0093] It can be known from the embodiments 1-4 that, by adjusting the diameter of the template microspheres and the thickness of the isolation layer, the size and spacing of the micro-pore structure obtained finally can be flexibly adjusted, for example, it can be known from the embodiments 1, 2-4 that, when the particle size of the template microspheres is determined, the pore diameter and pore spacing of the micro-pore structure can be controlled by adjusting the thickness of the isolation layer.

[0094] Embodiment 5

[0095] In this embodiment, the conductive microsphere array is constructed based on the ordered and spaced micro-pore structure in the embodiment 1, and the operation is as follows:

[0096] The nickel-plated PS microspheres with a diameter of about 3.25 μm are used as the conductive microspheres, and the conductive microsphere array is constructed by the friction-assisted assembly microsphere method, that is, a small amount of conductive microspheres are placed on the side of the PDMS template with the micro-pore structure prepared in the embodiment 1, a cuboid-shaped PDMS flexible material is used to rub the conductive microspheres on the surface of the PDMS template in the same direction for 5-10 times, and the excess conductive microspheres are wiped off, so that the conductive microspheres enter the micro-pores on the PDMS template to realize the arrayed arrangement of the conductive microspheres, as shown in the a and b of FIG. 2. Figure 6 As shown in the a and b of FIG. 2, finally, the arrayed conductive microspheres are transferred to the target substrate using a commercial adhesive tape or a resin adhesive film, that is, the conductive microsphere array is constructed, as shown in the c and d of FIG. 2. Figure 6 As shown in the c and d of FIG. 2.

[0097] Embodiment 6

[0098] In this embodiment, the conductive microsphere array is constructed based on the ordered and spaced micro-pore structure in the embodiment 2, and the operation is as follows:

[0099] Nickel-coated PS microspheres with a diameter of about 3.25 μm were used as conductive microspheres. The conductive microsphere array was constructed by a rubbing-assisted assembly method as follows: a small amount of conductive microspheres were placed on the surface of the PDMS template with ordered and spaced micro-holes prepared in Example 2, a piece of cuboid-shaped PDMS flexible material was used to rub the conductive microspheres on the surface of the PDMS template in the same direction for 5-10 times, and the excess conductive microspheres were wiped off, so that the conductive microspheres entered the micro-holes on the PDMS template to realize the arrayed arrangement of the conductive microspheres, as shown in Figs. a and b of Figure 7 Finally, the arrayed conductive microspheres were transferred to a target substrate using a commercial adhesive tape or a resin adhesive film, i.e. a conductive microsphere array was constructed, as shown in Figs. c and d of Figure 7 .

[0100] Example 7

[0101] In this example, the conductive microsphere array was constructed based on the ordered and spaced micro-holes in Example 3, and the operation was as follows:

[0102] Nickel-coated PS microspheres with a diameter of about 3.25 μm were used as conductive microspheres. The conductive microsphere array was constructed by a rubbing-assisted assembly method as follows: a small amount of conductive microspheres were placed on the surface of the PDMS template with ordered and spaced micro-holes prepared in Example 3, a piece of cuboid-shaped PDMS flexible material was used to rub the conductive microspheres on the surface of the PDMS template in the same direction for 5-10 times, and the excess conductive microspheres were wiped off, so that the conductive microspheres entered the micro-holes on the PDMS template to realize the arrayed arrangement of the conductive microspheres, and finally, the arrayed conductive microspheres were transferred to a target substrate using a commercial adhesive tape or a resin adhesive film, i.e. a conductive microsphere array was constructed, as shown in Figs. a and b of Figure 8 .

[0103] Example 8

[0104] In this example, a preparation method of the ordered and spaced micro-holes was provided, and the steps were as follows:

[0105] (1) Coating an isolation agent on the surface of a substrate

[0106] Quartz was used as a substrate, and the substrate was sequentially ultrasonically cleaned in deionized water, acetone, anhydrous ethanol and deionized water for 8-20 min. The cleaned and dried substrate was placed in an oven at 60°C for drying for 30 min. A fluororesin coating was uniformly coated on the surface of the cleaned and dried substrate by a spin coating method, and the thickness of the isolation agent layer formed by coating was controlled to be 1.5±0.5 μm, to obtain a substrate with an isolation agent layer.

[0107] (2) Preparing a single-layer microsphere template

[0108] The single-layer microsphere template is prepared by the convection self-assembly method, and the operation is as follows:

[0109] The monodisperse PS microspheres with a particle size of 5 μm are used as the template microspheres, the template microspheres are added into the 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 0.5 wt%.

[0110] The substrate with the release agent layer is treated in the oxygen plasma for 1 min, and then is placed on a hot stage at 100°C with the side provided with the release agent layer upward, 0.3 mL of the template microsphere suspension is added dropwise onto the release agent layer of the substrate, the template microsphere suspension is slowly scraped along the same direction by means of the blade coating, and the moving speed of the blade during the blade coating is controlled to be 5.0 μm / s. In the process of evaporation of the solvent of the template microsphere suspension, the forces including the capillary force and the surface tension induce the template microspheres to be uniformly arranged along the direction of the blade coating. After the deionized water and the ethanol in the template microsphere suspension are completely evaporated, a single-layer microsphere template with the template microspheres arranged in a single-layer array on the substrate is obtained.

[0111] (3) Preparation of the PDMS template with ordered and spaced micro-pore structure

[0112] 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 template microspheres of the single-layer microsphere template to form a pouring layer, the thickness of the pouring layer is controlled to be 1 mm, and then the single-layer microsphere template is placed in a vacuum drying box for vacuum degassing, and is 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 is placed in anhydrous ethanol for ultrasonic cleaning for 4 h to remove the residual release agent and the template microspheres in the PDMS, and is dried to obtain a PDMS template with ordered and spaced micro-pore structure.

[0113] Example 9

[0114] In this example, a method for preparing an ordered and spaced micro-pore structure is provided, and the steps are as follows:

[0115] (1) Coating of the release agent on the surface of the substrate

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

[0117] (2) Preparation of the single-layer microsphere template

[0118] A monolayer microsphere template is prepared by a convection self-assembly method, and the operation is as follows:

[0119] Monodisperse PS microspheres with a particle size of 4 μm are used as template microspheres, and the template microspheres are added to anhydrous ethanol to obtain a template microsphere suspension with a template microsphere content of 0.1 wt%.

[0120] The substrate with the release agent layer is treated in an oxygen plasma for 1 min, and then placed on a hot stage at 60°C with the side provided with the release agent layer facing upwards. 0.2 mL of the template microsphere suspension is added dropwise to the release agent layer of the substrate, and the template microsphere suspension is slowly scraped along the same direction by scraping, with the moving speed of the scraper controlled at 1 μm / s. During the evaporation of the solvent of the template microsphere suspension, the forces including capillary force and surface tension induce the uniform arrangement of the template microspheres along the scraping direction. After the anhydrous ethanol in 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.

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

[0122] The PDMS prepolymer and the curing agent are thoroughly mixed in a mass ratio of 10:1 to obtain a PDMS prepolymer solution. The PDMS prepolymer solution is poured onto the monolayer microspheres of the monolayer microsphere template to form a pouring layer, and the thickness of the pouring layer is controlled at 1 mm. Then, the pouring layer is placed in a vacuum drying box 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 monolayer microsphere template and placed in anhydrous ethanol for ultrasonic cleaning for 4 h to remove the residual release agent and template microspheres in the PDMS. After drying, a PDMS template with an ordered and spaced microporous structure is obtained.

Claims

1. A method for preparing an ordered, spaced, porous structure, characterized in that, The method comprises the following steps: (1) applying an isolation agent on a clean and dry substrate to obtain a substrate with an isolation agent layer; the isolation agent is a fatty acid, paraffin oil, vaseline, silicone oil, polyvinyl alcohol or fluororesin paint; (2) constructing a monolayer array of monodisperse template microspheres on the isolation agent layer of the substrate to obtain a monolayer microsphere template; the thickness of the isolation agent layer is 4% to 50% of the diameter of the template microspheres; (3) pouring a polymer precursor solution on the template microspheres of the monolayer microsphere template to form a pouring layer, curing the polymer precursor solution 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 and spaced micro-porous structure. In step (2), the template microspheres 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 pouring layer is cured in step (3).

2. The method of claim 1, wherein the ordered, spaced-apart, porous structure is formed by a process comprising: In step (2), the monolayer microsphere template is prepared by a gas-liquid interface self-assembly method or a convection self-assembly method.

3. The method of claim 2, wherein the ordered array of spaced-apart microcavities is formed by the steps of: In step (2), the monolayer microsphere template is prepared by the gas-liquid interface self-assembly method as follows: ​ The substrate with the isolation agent layer is subjected to oxygen plasma treatment, and then immersed in an aqueous solvent in a container with the side provided with the isolation agent layer facing the liquid surface. Template microsphere suspension is slowly added to the liquid surface until the liquid surface is covered with a tightly packed template microsphere film layer. Then, a water-soluble surfactant solution is added to the container to make the template microspheres tightly arranged on the liquid surface. Then, the substrate is taken out of the container, and the side provided with the isolation agent layer is kept parallel to the liquid surface during the process of taking out the substrate. After the solvent on the taken-out substrate is completely evaporated, a monolayer array of template microspheres on the substrate is obtained, i.e., a monolayer microsphere template. 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 concentration of the aqueous solution of the water-soluble polymer is 2 wt% to 10 wt%.

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 1 wt% to 10 wt%. The solvent used for preparing 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 2 wt% to 8 wt%.

5. The method for preparing the ordered spaced microporous structure according to claim 2, characterized in that, In step (2), the monolayer microsphere template is prepared by the convection self-assembly method as follows: The substrate with the isolation agent layer is subjected to oxygen plasma treatment, and then placed on a hot stage at 60 to 100°C with the side provided with the isolation agent layer facing upward. Template microsphere suspension is added to the isolation agent layer, and the template microsphere suspension is scraped in the same direction by scraping to induce the template microspheres to be uniformly arranged in the scraping direction under the action of forces including capillary force and surface tension during the evaporation of the solvent of the template microsphere suspension. After the solvent of the template microsphere suspension is completely evaporated, a monolayer array of template microspheres on the substrate is obtained, i.e., a monolayer microsphere template.

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

7. The method of claim 1 to 6, wherein The thickness of the casting layer is at least 10 times the diameter of the template microspheres.

8. A method of preparing an array of microspheres, characterized by, The conductive microspheres are filled into the micropores of the polymer template with ordered and spaced micropores prepared by the method of any one of claims 1 to 7, the conductive microspheres are filled into the micropores of the polymer template with ordered and spaced micropores, the arrayed arrangement of the conductive microspheres is achieved, the arrayed arrangement of the conductive microspheres is transferred to a target substrate, and a microsphere array is obtained.

9. The method for preparing the microsphere array according to claim 8, 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 of the polymer template with ordered and spaced micropores.

Images