A method for controllable preparation of monodisperse microdroplets based on the wetting principle

Abstract

The present invention provides a method for controllably preparing monodisperse microdroplets based on the infiltration principle. The method adopts a microporous tube in combination with a collection container for preparation, wherein the microporous tube has a hydrophobic microporous bottom plate. The method comprises the following steps: (1) placing a continuous phase in the collection container so that the liquid level of the continuous phase is horizontal, placing the microporous tube above the collection container, adjusting the placement height of the collection container so that the continuous phase contacts the hydrophobic microporous bottom plate but does not contact the micropores, after the continuous phase contacts the hydrophobic microporous bottom plate, infiltration occurs between the continuous phase and the hydrophobic microporous bottom plate, and further adjusting the placement height of the collection container so that the liquid level after infiltration is located below the micropores, and the distance between the lower edge of the micropores and the upper edge of the liquid level after infiltration is 200-2200 μm; and (2) injecting a dispersed phase into the microporous tube, the dispersed phase passing through the micropores and contacting the continuous phase spread on the hydrophobic microporous bottom plate, and generating monodisperse microdroplets under the induction of the interfacial tension difference between the air phase, the dispersed phase, and the continuous phase.

Description

Technical Field

[0001] The invention belongs to the technical field of emulsion preparation, and relates to a microfluidic method for controllably preparing monodisperse emulsion based on the infiltration principle. Background Art

[0002] Microdroplets with uniform structure and controllable size have broad application prospects in many fields, including chemical synthesis and analysis, pharmaceutical chemistry, cell research, and functional material synthesis. There are many ways to prepare microdroplets. Traditional preparation techniques, including oscillation, stirring, shaking, ultrasound, homogenization, membrane emulsification, and spraying, have the advantages of simple operation and low equipment requirements. However, they require high mechanical forces during the preparation process, and the energy utilization rate of the microdroplet formation process is generally only about 5%. Moreover, the microdroplets prepared by these traditional preparation techniques are generally poorly monodisperse and difficult to flexibly control in size, making it difficult to meet the precise requirements for microdroplet size in applications.

[0003] Droplet microfluidics, which has emerged in recent years, is an emerging technology that combines the preparation and manipulation of microdroplets for various applications. It not only solves the problem of low energy utilization efficiency in traditional microdroplet preparation technology, but also can obtain microdroplets with uniform structure and adjustable size according to the needs of researchers. However, the microfluidic devices required for the implementation of droplet microfluidics need to be hand-made by experienced researchers. The size and structure of the device will affect the size control rules of the microdroplets, and the device will experience reduced sealing during long-term storage, causing leakage and other problems. Moreover, droplet microfluidics, which is highly dependent on shear force, will also face the problem of reduced monodispersity of microdroplets due to uneven distribution of fluid in the microfluidic network during the parallelization process of the device. Therefore, droplet microfluidics still has some problems in the "scale-up" preparation process of microdroplet production. Furthermore, the use of traditional microfluidics for microdroplet-templated microparticle synthesis typically involves an online reaction between the dispersed phase droplets and the continuous phase within the microchannels of the microfluidic device. This process of converting the microdroplets into solid particles can easily clog the microchannels, thereby affecting the continuous and controllable preparation of polymer microparticles within the microfluidic device. Therefore, the development of microfluidic emulsification technology with convenient operation and simple device structure is of great significance for the controllable preparation of monodisperse microdroplets and monodisperse polymer microparticles, but significant challenges remain. Summary of the Invention

[0004] In response to the problems of low energy utilization, difficulty in scaling up microdroplet production, and cumbersome device construction process in existing microdroplet preparation methods, the present invention provides a method for controllably preparing monodisperse microdroplets based on the infiltration principle, which simplifies the microdroplet preparation process, improves its preparation efficiency, realizes efficient and controllable preparation of monodisperse microdroplets, and promotes scaled-up production.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0006] A method for controllably preparing monodisperse microdroplets based on the infiltration principle employs a microporous tube in conjunction with a collection container. The microporous tube comprises a dispersed phase containing tube and a hydrophobic microporous bottom plate, wherein the hydrophobic microporous bottom plate is a flat plate provided with micropores. The hydrophobic microporous bottom plate is fixed to one end of the dispersed phase containing tube to seal the end of the dispersed phase containing tube. The method comprises the following steps:

[0007] ① Place the continuous phase in a collection container so that the liquid surface of the continuous phase is horizontal, place a microporous tube above the collection container so that the hydrophobic microporous bottom plate is inclined and the end of the microporous tube with the hydrophobic microporous bottom plate is lower than the end without the hydrophobic microporous bottom plate; adjust the height of the collection container so that the continuous phase contacts the hydrophobic microporous bottom plate but does not contact the micropores. After the continuous phase contacts the hydrophobic microporous bottom plate, infiltration occurs between the continuous phase and the hydrophobic microporous bottom plate. Continue to adjust the height of the collection container so that the liquid surface after infiltration is below the micropores, and the distance (L) between the lower edge of the micropores and the upper edge of the liquid surface after infiltration is 200 to 2200 μm.

[0008] ② The dispersed phase is injected into the microporous tube. The dispersed phase passes through the micropores and contacts the continuous phase spread on the hydrophobic microporous bottom plate. Monodisperse microdroplets are generated under the induction of the interfacial tension difference between the air phase, the dispersed phase and the continuous phase.

[0009] The interfacial tension between the dispersed phase and the continuous phase at the injection tube outlet should satisfy γ AW >γ AO +γ WO , γ AW is the interfacial tension between the air phase and the dispersed phase, γ AO is the interfacial tension between the air phase and the continuous phase, γ WO is the interfacial tension between the dispersed phase and the continuous phase; during the preparation process, the vertical distance (h) from the liquid surface of the dispersed phase to the micropore is controlled to be 20-65 cm, the angle (θ) between the hydrophobic micropore bottom plate and the horizontal plane is controlled to remain constant, and the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is controlled to remain constant.

[0010] In the technical solution of the method for preparing monodisperse microdroplets in a controlled manner based on the infiltration principle, the micropores on the hydrophobic microporous bottom plate (1-2) are circular, and the micropore diameter (D) is 20 to 60 μm.

[0011] In step ① of the technical solution of the method for preparing monodisperse microdroplets based on the infiltration principle, the lower edge of the micropore refers to the position where the micropore is closest to the liquid surface after infiltration occurs between the continuous phase and the hydrophobic micropore bottom plate. Since this position is the position with the lowest vertical height in the entire micropore, it is called the lower edge of the micropore.

[0012] In step ① of the technical solution of the method for preparing monodisperse microdroplets based on the infiltration principle, when infiltration occurs between the continuous phase and the hydrophobic microporous bottom plate and the infiltration liquid surface reaches stability, the upper edge of the infiltration liquid surface is on a straight line parallel to the horizontal plane.

[0013] In the technical solution of the method for preparing monodisperse microdroplets based on the infiltration principle, the number of micropores on the hydrophobic microporous bottom plate is at least 1; when the number of micropores on the hydrophobic microporous bottom plate exceeds 1, the micropores are identical and the centers of the micropores are located on the same straight line, and the distance between adjacent micropores is at least 2 μm.

[0014] Furthermore, in the technical solution of the method for preparing monodisperse microdroplets based on the infiltration principle, when the number of micropores on the hydrophobic microporous bottom plate exceeds one, the distance (L) between the lower edge of each micropore and the upper edge of the liquid surface after infiltration is controlled to be equal in step ①.

[0015] Furthermore, in the technical solution of the method for preparing monodisperse microdroplets based on the infiltration principle, a scale line is provided on the hydrophobic microporous bottom plate; when the number of micropores on the hydrophobic microporous bottom plate is 1, the scale line and the diameter of the micropore are parallel to each other; when the number of micropores on the hydrophobic microporous bottom plate exceeds 1, the scale line and the line connecting the centers of the micropores are parallel to each other.

[0016] In the technical solution of the method for preparing monodisperse microdroplets based on the infiltration principle, when scale lines are provided on the hydrophobic microporous bottom plate, the scale lines on the hydrophobic microporous bottom plate are controlled to be parallel to the horizontal plane in step ①. Usually, the scale lines serving as reference lines are located below the edge of the micropores and the angle of the microporous hydrophobic bottom plate is controlled so that the scale lines are parallel to the horizontal plane.

[0017] In the technical solution for the method for controllably preparing monodisperse microdroplets based on the principle of wetting, the hydrophobic microporous base plate has a thickness of 0.1 to 1 mm and is made of a material with a hydrophobic surface. The hydrophobic microporous base plate does not deform during the monodisperse microdroplet preparation process. A feasible hydrophobic microporous base plate is a stainless steel plate with a hydrophobic surface treatment.

[0018] In the technical solution of the method for controllably preparing monodisperse microdroplets based on the infiltration principle, the inclined setting of the hydrophobic microporous bottom plate in step ① means that the angle (θ) between the hydrophobic microporous bottom plate and the horizontal plane is 20° to 60°.

[0019] In the technical solution for the controllable preparation of monodisperse microdroplets based on the infiltration principle, the dispersed phase holding tube is flush on all sides at one end of the hydrophobic microporous base plate. The dispersed phase holding tube can be a straight or curved tube with both ends open. The shape of the dispersed phase holding tube is not limited and can be a tube with a circular, square, or other cross-sectional shape. For example, a circular tube with an inner diameter of at least 10 mm can be used as the dispersed phase holding tube.

[0020] In the above-mentioned technical solution of the method for preparing monodisperse microdroplets in a controllable manner based on the infiltration principle, the length of the dispersed phase containing tube should meet the following requirements: during the preparation of monodisperse microdroplets, the vertical distance (h) from the liquid surface of the dispersed phase contained in the dispersed phase containing tube to the micropores on the hydrophobic microporous bottom plate can be maintained at 20 to 65 cm.

[0021] In the technical solution of the method for preparing monodisperse microdroplets in a controllable manner based on the infiltration principle, the dispersed phase is an aqueous phase and the continuous phase is an oil phase.

[0022] Furthermore, in the technical solution for the controllable preparation of monodisperse microdroplets based on the infiltration principle, the continuous phase may also contain an agent for stabilizing the interface, including a surfactant and / or nanoparticles for stabilizing the interface. The surfactant is dissolved in the continuous phase, and the nanoparticles for stabilizing the interface are uniformly dispersed in the continuous phase. One feasible method for preparing the continuous phase is to dissolve or uniformly disperse the agent for stabilizing the interface in an oil phase solvent to obtain the continuous phase.

[0023] In the technical solution for the controllable preparation of monodisperse microdroplets based on the infiltration principle, the dispersed phase contains at least one of a functional polymer, a monomer, a thickener, a salt, and functional nanoparticles soluble in an aqueous solvent. A feasible method for preparing the dispersed phase is to dissolve at least one of the functional polymer, monomer, thickener, salt, and functional nanoparticles soluble in an aqueous solution in an aqueous solvent to obtain the dispersed phase.

[0024] When the dispersed phase contains functional polymers or monomers, the monodisperse microdroplets prepared by the above technical solution can obtain functionalized monodisperse polymer microspheres after solidification; when the dispersed phase contains functional nanoparticles and functional polymers or monomers, the monodisperse microdroplets prepared by the above technical solution can obtain functionalized monodisperse polymer microspheres containing nanoparticles after solidification.

[0025] In practical applications, the formulas of the dispersed phase and the continuous phase can be determined according to specific application requirements, and the formulas of the dispersed phase and the continuous phase can be determined with reference to existing technologies.

[0026] The diameter of the monodisperse microdroplets prepared by the above-mentioned method for preparing monodisperse microdroplets based on the infiltration principle is mainly determined by the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration during the preparation process. At the same time, the size of the micropores on the hydrophobic microporous bottom plate will also affect the diameter of the monodisperse microdroplets. In practical applications, when the micropore diameter is fixed and the vertical distance (h) from the liquid surface of the dispersed phase to the micropore is determined, the diameter of the monodisperse microdroplets can be flexibly adjusted by adjusting the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration. Generally, the diameter of the monodisperse microdroplets prepared by the above-mentioned technical solution is any value between 180 and 1000 μm.

[0027] The present invention is based on the interfacial tension difference (γ AW >γ AO +γ WO ) under the induction of a continuous phase, which spreads on the surface of a dispersed phase droplet passing through a micropore to generate monodisperse microdroplets. The microdroplet generation process is essentially unaffected by the fluid's physical properties, resolving issues such as poor droplet production stability and repeatability in existing microdroplet preparation methods, which are affected by other factors such as high viscosity. Furthermore, the structure and construction process of the apparatus relied upon by the method of the present invention are simple. The number of micropores on the hydrophobic microporous base of the microporous tube can be adjusted as needed. Under certain other conditions, the number of micropores does not affect the size and monodispersity of the microdroplets, making it highly advantageous for industrial scale-up production.

[0028] Compared with the prior art, the technical solution provided by the present invention produces the following beneficial technical effects:

[0029] 1. The present invention provides a method for controllably preparing monodisperse microdroplets based on the infiltration principle. By using a microporous tube in conjunction with a collection container, the micropore size, the distance between the lower edge of the micropore and the upper edge of the infiltrated liquid surface, the vertical distance from the liquid surface of the dispersed phase to the micropore, and the angle between the hydrophobic microporous bottom plate and the horizontal plane are controlled to appropriate values. By selecting the dispersed phase and the continuous phase, the continuous preparation of monodisperse microdroplets can be achieved without the aid of any external power. The method has the characteristics of simple device construction process, simple process operation and low energy consumption, and can solve the problems of low energy utilization, low production efficiency and cumbersome device construction process in existing microdroplet preparation methods.

[0030] 2. The present invention experimentally demonstrates that when a hydrophobic microporous base plate has multiple micropores, each micropore operates as a relatively independent system to generate microdroplets, without interfering with each other. Under otherwise stable experimental conditions, the prepared microdroplets exhibit excellent monodispersity, with no significant decrease in monodispersity as the number of micropores increases. This demonstrates that the method of the present invention can achieve efficient, mass-produced monodisperse microdroplets by increasing the number of micropores on the hydrophobic microporous base plate of a microporous tube, resolving the existing difficulty in scaling up the production of monodisperse microdroplets.

[0031] 3. Experiments have confirmed that the method of the present invention can produce microdroplets from fluids with viscosities ranging from 1 to 3400 mPa·s. This method is applicable not only to low-viscosity dispersed phases but also to high-viscosity dispersed phases. This demonstrates that the method of the present invention is largely unaffected by the physical properties of the fluid during the microdroplet generation process and can produce monodisperse microdroplets over a very wide viscosity range, effectively resolving the problem of poor stability associated with existing droplet preparation methods when producing monodisperse microdroplets from high-viscosity fluids.

[0032] 4. When the monodisperse microdroplets prepared by the method of the present invention are used as templates to prepare polymer microparticles, the solidification process of the microdroplets does not occur in the microporous tube. This can solve the problem of existing droplet preparation methods that solidify droplets in the microchannel and easily cause device clogging, thereby limiting the continuous production of microparticles. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the structure of the microporous tube, where (A) and (B) represent the cases where the hydrophobic microporous bottom plate has one and multiple micropores, respectively.

[0034] Figure 2 It is a schematic diagram of the process of preparing monodisperse microdroplets according to the present invention.

[0035] Figures 1-2 In the figure, 1 is microporous tube, 1-1 is dispersed phase holding tube, 1-2 is hydrophobic microporous bottom plate, 2 is collection container, h is the vertical distance from the liquid surface of the dispersed phase to the micropore, γ AW —Interfacial tension between air phase and dispersed phase, γ AO —Interfacial tension between the air phase and the continuous phase, γ WO —interfacial tension between the dispersed phase and the continuous phase, θ—the angle between the hydrophobic micropore bottom plate and the horizontal plane, L—the distance between the lower edge of the micropore and the upper edge of the infiltrated liquid surface, and D—micropore diameter.

[0036] Figure 3 This is a diagram of the W / O micro-droplet generation process captured by a high-speed camera at a shooting rate of 1000 fps in Example 3.

[0037] Figure 4 Figure a) shows the effect of h and L on the diameter of W / O droplets in Example 4. Figure 4 Figure b) shows the effect of θ and L on the diameter of W / O droplets in Example 5. Figure 4 Figure c) shows the effect of the viscosity (μ) of the dispersed phase on the diameter of the W / O droplets in Examples 6 to 10. Figure 4 Figure d) shows the effect of micropore diameter (D) on the W / O microdroplet diameter in Example 11.

[0038] Figure 5 Figures a) to c) are optical micrographs and particle size distribution diagrams of W / O microdroplets prepared in Example 12. Figure 5 Figure d) shows the change of the diameter of the W / O microdroplets prepared in Example 12 with L.

[0039] Figure 6 Figure a) shows the relationship between the diameter and CV value of the W / O microdroplets prepared in Example 13 and L. Figure 6 Figure b) shows the relationship between the dispersed phase flow rate (q) and the CV value of the prepared W / O microdroplets in Example 14 as a function of the number of micropores (n).

[0040] Figure 7 15 is a diagram of the generation process of W / O microdroplets captured by a high-speed camera, wherein Figures a) to d) correspond to the cases where the hydrophobic microporous bottom plate has 1, 2, 3, and 9 micropores, respectively.

[0041] Figure 8 The optical microscope photograph of the W / O microdroplets prepared in Example 15 and the average diameter D of the W / O microdroplets are shown in FIG. avg And CV value statistical results, where a) to d) correspond to the cases with 1, 2, 3 and 9 micropores on the hydrophobic microporous bottom plate, respectively.

[0042] Figure 9 Figures a) to c) are scanning electron micrographs of the PEGDA particles prepared in Example 16. Figure 9 Figure d) is an optical micrograph of PNIPAm particles prepared in Example 17 (L = 1400 μm). Figure 9 Figure e) is an optical photograph of PNIPAm particles prepared in Example 17 (L = 400 μm). Figure 9 Figure f) is an optical micrograph of the PAm particles prepared in Example 18 (L=800 μm). Figure 9 Figure g) is an optical photograph of the PAm particles prepared in Example 18 (L=600 μm). DETAILED DESCRIPTION

[0043] The following examples further illustrate the method for controllably preparing monodisperse microdroplets based on the infiltration principle provided by the present invention. It should be noted that the following examples are intended only to further illustrate the present invention and are not to be construed as limiting the scope of the present invention. Based on the above disclosure, non-essential improvements and adjustments made by those skilled in the art to the present invention for implementation remain within the scope of the present invention.

[0044] Example 1

[0045] In this embodiment, a structure of a microporous tube 1 for controllably preparing monodisperse microdroplets is provided. The structural schematic diagram of the microporous tube 1 is shown in FIG. Figure 1 shown.

[0046] The microporous tube 1 consists of a dispersed phase containing tube 1-1 and a hydrophobic microporous bottom plate 1-2. The hydrophobic microporous bottom plate 1-2 is a flat plate provided with micropores and scale lines. The size of the hydrophobic microporous bottom plate 1-2 is larger than the size of the end of the dispersed phase containing tube. The hydrophobic microporous bottom plate is fixed to one end of the dispersed phase containing tube 1-1 to seal one end of the dispersed phase containing tube.

[0047] Specifically:

[0048] The dispersed phase containing tube 1-1 is a cylindrical tube with open ends. The two end faces of the dispersed phase containing tube 1-1 are perpendicular to the axis of the dispersed phase containing tube 1-1. The inner diameter of the dispersed phase containing tube 1-1 is at least 10 mm.

[0049] There is at least one micropore set on the hydrophobic microporous base plate 1-2, and the micropore is preferably circular, with a diameter of 20 to 60 μm; for ease of observation, at least one scale line is set 1 mm away from the edge of the micropore, and when the number of scale lines exceeds one, the scale lines are parallel to each other; when the number of micropores on the hydrophobic microporous base plate 1-2 exceeds one, the sizes of the micropores are the same and the centers of the circles are located on the same straight line, and the scale lines are parallel to the line connecting the centers of the micropores; when one micropore is set on the hydrophobic microporous base plate 1-2, the scale lines are set parallel to the diameter of the micropore; the thickness of the hydrophobic microporous base plate 1-2 is 0.1 to 1 mm, and it is made of a material with a hydrophobic surface. The thickness and material of the hydrophobic microporous base plate 1-2 should be selected to ensure that it does not deform under the pressure of the dispersed phase contained in the dispersed phase holding tube 1-1 during the preparation of microdroplets.

[0050] The hydrophobic microporous bottom plate 1-2 is bonded to one end of the dispersed phase containing tube 1-1 by adhesive to completely seal the edge of the one end of the dispersed phase containing tube.

[0051] More specifically, this embodiment provides two types of microporous tubes, as follows:

[0052] The structural diagram of the first microporous tube is as follows Figure 1As shown, it consists of a dispersed phase containing tube 1-1 and a hydrophobic microporous base plate 1-2. The dispersed phase containing tube 1-1 is a cylindrical transparent glass tube with open ends. The end surfaces of the dispersed phase containing tube 1-1 are perpendicular to the axis of the dispersed phase containing tube 1-1. The dispersed phase containing tube 1-1 has an outer diameter of 20mm and an inner diameter of 18mm. The dispersed phase containing tube 1-1 is 100cm long. The hydrophobic microporous base plate 1-2 is provided with one micropore and one scale line. The micropore is circular with a diameter of 40μm. The scale lines are parallel to the diameter of the micropore. The distance between the scale lines and the edge of the micropore is 1mm, and the length of each scale line is 5mm. The hydrophobic microporous base plate 1-2 is obtained by providing micropores on a square stainless steel plate with a thickness of 1mm and a size of 30*30mm, and then applying a hydrophobic modification with a Niuying nano waterproof coating. The hydrophobic microporous base plate 1-2 does not deform under the pressure of the dispersed phase contained in the dispersed phase containing tube 1-1. The hydrophobic microporous bottom plate 1-2 is bonded to one end of the dispersed phase containing tube 1-1 by adhesive AB glue to completely seal the edge of one end of the dispersed phase containing tube. After bonding, the hydrophobic microporous bottom plate 1-2 is perpendicular to the axis of the dispersed phase containing tube 1-1.

[0053] The structural diagram of the second microporous tube is as follows Figure 2 As shown, the dispersed phase containing tube 1-1 and the hydrophobic microporous bottom plate 1-2 are composed. The dispersed phase containing tube 1-1 is a cylindrical transparent glass tube with open ends. The end surfaces of the dispersed phase containing tube 1-1 are perpendicular to the axis of the dispersed phase containing tube 1-1. The dispersed phase containing tube 1-1 has an outer diameter of 20 mm and an inner diameter of 18 mm. The dispersed phase containing tube 1-1 is 100 cm long. The hydrophobic microporous base plate 1-2 is provided with a plurality of micropores, for example, 2 to 9 micropores, each of which is a circular hole with a diameter of 40 μm, the centers of each micropore are located on the same straight line, the distance between adjacent micropores is at least 2 μm, and one scale line is provided, the scale line is parallel to the line connecting the centers of each micropore, the distance between the scale line and the edge of the micropore is 1 mm, and the length of the scale line is 5 mm; the hydrophobic microporous base plate 1-2 is obtained by providing micropores on a square stainless steel plate with a thickness of 1 mm and a size of 30*30 mm, and then hydrophobically modifying it with a Niuying nano waterproof coating. The hydrophobic microporous base plate 1-2 does not deform under the pressure of the dispersed phase in the dispersed phase containing tube 1-1. The hydrophobic microporous base plate 1-2 is bonded to one end of the dispersed phase containing tube 1-1 with an adhesive AB glue to completely seal the edge of the dispersed phase containing tube. After bonding, the hydrophobic microporous base plate 1-2 is perpendicular to the axis of the dispersed phase containing tube 1-1.

[0054] Example 2

[0055] In this embodiment, a method for using a microporous tube in conjunction with a collection container is provided.

[0056] (1) Tilt the microporous tube so that the end of the microporous tube with the hydrophobic microporous base is lower than the end without the hydrophobic microporous base, and the scale line on the hydrophobic perforated base is parallel to the horizontal plane. For example, the microporous tube can be fixed on an angle-adjustable tilted table to meet the above positional relationship.

[0057] (2) Place a collection container below the microporous tube, with the continuous phase contained in the collection container and the liquid level of the continuous phase in a horizontal state. Adjust the position of the collection container so that the continuous phase contacts the hydrophobic microporous bottom plate but does not contact the micropores and the scale line. At this time, infiltration occurs between the continuous phase and the hydrophobic microporous bottom plate. Using the scale line as a reference, continue to adjust the position of the collection container so that the liquid level after infiltration is located below the micropores, and the distance (L) between the lower edge of the micropores and the upper edge of the infiltrated liquid level reaches the target distance. This completes the construction of the device for controllably preparing monodisperse microdroplets.

[0058] For example, the collecting container can be placed on a lifting platform so that the liquid level of the continuous phase contained in the collecting container is in a horizontal state, and the position of the collecting container can be adjusted by the lifting platform so that the liquid level of the continuous phase and the micropores meet the above relationship.

[0059] (3) Figure 2 As shown, the dispersed phase is injected into the microporous tube, and the vertical distance (h) from the liquid surface of the dispersed phase to the micropore is controlled to be 20-65 cm. The dispersed phase passes through the micropore and contacts the continuous phase spread on the hydrophobic microporous bottom plate. The interfacial tension difference (γ AW >γ AO +γ WO ) induces the continuous phase to spread on the surface of the dispersed phase droplets passing through the micropores, generating monodisperse microdroplets. During the preparation of monodisperse microdroplets, the angle (θ) between the hydrophobic micropore base and the horizontal plane is kept constant, as is the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration. The micropore diameter (D) is selected between 20 and 60 μm.

[0060] Example 3

[0061] In this embodiment, the method of the present invention is described by taking the preparation process of monodisperse water-in-oil (W / O) microdroplets as an example, and the steps are as follows:

[0062] (1) Preparation of dispersed phase and continuous phase

[0063] Deionized water was used as the dispersed phase; the oil-soluble surfactant polyisobutylene succinimide (T154) was dissolved in tetradecane to obtain a continuous phase, and the concentration of T154 in the continuous phase was 0.08 g / mL.

[0064] (2) Preparation of monodisperse W / O microdroplets

[0065] Following the procedures of Example 2, the first microporous tube of Example 1 was combined with a collection container, an inclined table, and a lifting platform to construct an apparatus for controllably preparing monodisperse microdroplets. Specifically, a hydrophobic microporous base plate with a micropore diameter of 40 μm was used. The inclination of the inclined table was adjusted to adjust the angle (θ) between the hydrophobic microporous base plate of the microporous tube and the horizontal plane to 30°. After the hydrophobic microporous base plate and the continuous phase in the collection container were infiltrated, the upper edge of the infiltrated liquid surface was located at the scale line below the micropore (the upper edge of the infiltrated liquid surface coincided with the scale line below the micropore). In other words, the distance (L) between the lower edge of the micropore and the upper edge of the infiltrated liquid surface was 1 mm.

[0066] The dispersed phase is injected into the microporous tube, passes through the micropores and contacts the continuous phase spread on the hydrophobic microporous bottom plate. The dispersed phase is in the air phase (A)-dispersed phase (W)-continuous phase (O) three-phase interfacial tension difference (γ AW >γ AO +γ WO ) induced by the continuous phase, it spreads on the surface of the dispersed phase droplets passing through the micropores and engulfs the dispersed phase droplets into the continuous phase through "endocytosis," generating monodisperse W / O microdroplets. During this preparation step, the vertical distance (h) from the dispersed phase surface to the micropores was controlled at 40 cm, the angle (θ) between the hydrophobic micropore bottom and the horizontal plane was kept constant at 30°, and the distance (L) between the lower edge of the micropores and the upper edge of the liquid surface after infiltration was kept constant at 1 mm.

[0067] During the preparation process, the formation process of W / O microdroplets was observed using a high-speed camera. Figure 3 shown.

[0068] Example 4

[0069] In this example, the effects of the vertical distance between the liquid surface of the dispersed phase and the micropores, and the distance between the micropore edge and the highest point of the liquid surface after wetting in the direction of the hydrophobic micropore bottom plate on the size of the W / O droplets were investigated.

[0070] In this embodiment, a total of 10 sets of experiments were conducted. In each of the 10 sets of experiments, the vertical distance (h) between the liquid surface of the dispersed phase and the micropores was controlled to be 25 cm, 30 cm, 35 cm, 40 cm, 45 cm, 50 cm, 55 cm, 60 cm, 67 cm, and 70 cm, respectively. At the same time, under each distance condition, the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration was adjusted to be constant at 200 μm, 400 μm, 600 μm, 800 μm, and 1000 μm, respectively. Except for the above experimental conditions, the other operations were the same as those in Example 3.

[0071] The monodisperse W / O droplets prepared in 10 groups of experiments in this example were observed using an optical microscope, and the diameters of the W / O droplets were counted. The results are as follows: Figure 4 As shown in Figure a), the figure shows that when the distance between the micropore edge and the highest point of the liquid surface after infiltration in the direction of the hydrophobic micropore base is fixed, the diameter of the prepared W / O microdroplets is almost unaffected when the vertical distance (h) from the liquid surface of the dispersed phase to the micropore varies within the range of 25 to 60 cm. When the vertical distance (h) from the liquid surface of the dispersed phase to the micropore is fixed, and the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration varies within the range of 200 to 1000 μm, the diameter of the prepared W / O microdroplets increases as the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration increases.

[0072] Example 5

[0073] In this example, the effects of the angle between the hydrophobic microporous bottom plate and the horizontal plane, and the distance between the microporous edge and the highest point of the liquid surface after immersion in the direction of the hydrophobic microporous bottom plate on the size of the W / O microdroplets were investigated.

[0074] This embodiment conducted a total of five experiments. In each of the five experiments, the angle (θ) between the hydrophobic microporous bottom plate and the horizontal plane was controlled to be 20°, 30°, 40°, 50°, and 60°, respectively. At the same time, under each angle condition, the distance (L) between the lower edge of the microporous hole and the upper edge of the liquid surface after infiltration was adjusted to be constant at 200 μm, 400 μm, 600 μm, 800 μm, and 1000 μm, respectively. Except for the above experimental conditions, the other operations were the same as those in Example 3.

[0075] The monodisperse W / O microdroplets prepared in the five groups of experiments in this example were observed using an optical microscope, and the diameters of the W / O microdroplets were counted. The results are as follows: Figure 4 As shown in Figure b), the figure shows that when the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is fixed, the diameter of the prepared W / O microdroplets is almost unaffected when the angle (θ) between the hydrophobic micropore base and the horizontal plane varies from 20° to 60°. When the angle (θ) between the hydrophobic micropore base and the horizontal plane is fixed, and the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is varied from 200 to 1000 μm, the diameter of the prepared W / O microdroplets increases as the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration increases.

[0076] Example 6

[0077] In this embodiment, the method of the present invention is described by taking the preparation process of monodisperse W / O microdroplets as an example, and the steps are as follows:

[0078] (1) Preparation of dispersed phase and continuous phase

[0079] Sodium alginate was dissolved in deionized water to obtain a dispersed phase, wherein the concentration of sodium alginate in the dispersed phase was 0.0025 g / mL. T154 was dissolved in tetradecane to obtain a continuous phase, wherein the concentration of T154 in the continuous phase was 0.08 g / mL.

[0080] (2) Preparation of monodisperse W / O microdroplets

[0081] The operation of this step is basically the same as that of Example 3, except that the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is adjusted to 200 μm. Finally, monodisperse W / O microdroplets are prepared.

[0082] Example 7

[0083] The operation of this example is basically the same as that of Example 6, except that the concentration of sodium alginate in the dispersed phase is 0.005 g / mL. Finally, monodisperse W / O microdroplets are prepared.

[0084] Example 8

[0085] The operation of this example is basically the same as that of Example 6, except that the concentration of sodium alginate in the dispersed phase is 0.0075 g / mL. Finally, monodisperse W / O microdroplets are prepared.

[0086] Example 9

[0087] The operation of this example is basically the same as that of Example 6, except that the concentration of sodium alginate in the dispersed phase is 0.01 g / mL. Finally, monodisperse W / O microdroplets are prepared.

[0088] Example 10

[0089] The operation of this example is basically the same as that of Example 6, except that the concentration of sodium alginate in the dispersed phase is 0.02 g / mL. Finally, monodisperse W / O microdroplets are prepared.

[0090] When the dispersed phase is composed of water and sodium alginate, when the concentrations of sodium alginate in the dispersed phase are 0, 0.0025, 0.005, 0.0075, 0.01, and 0.02 g / mL, respectively, the corresponding viscosities (μ) of the dispersed phase are 1, 18.89, 51.2, 128, 210.6, and 3389 mPa·s, respectively.

[0091] The monodisperse W / O microdroplets prepared by using the six dispersed phases with different viscosities under the same experimental conditions were observed using an optical microscope, and the diameters of the W / O microdroplets were counted. The results are as follows: Figure 4As shown in Figure c), under the same experimental conditions, the diameter of the prepared W / O microdroplets remains essentially unchanged as the viscosity of the dispersed phase increases. This indicates that the method provided by the present invention is not limited by the viscosity of the dispersed phase when preparing monodisperse microdroplets and is applicable not only to dispersed phases with low viscosities but also to dispersed phases with high viscosities.

[0092] Example 11

[0093] In this example, the effect of the diameter of the micropores on the hydrophobic microporous base plate on the size of the W / O microdroplets was investigated.

[0094] This example conducted seven experiments. The diameters of the micropores on the hydrophobic microporous base plate were 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, and 60 μm, respectively. The distance (L) between the lower edge of the micropores and the upper edge of the liquid surface after infiltration was adjusted to 200 μm. Aside from these experimental conditions, the remaining procedures were identical to those of Example 3.

[0095] The monodisperse W / O droplets prepared in the seven groups of experiments in this example were observed using an optical microscope, and the diameters of the W / O droplets were counted. The results are as follows: Figure 4 As shown in Figure d), the diameter of the prepared W / O microdroplets increases with the increase in micropore diameter under the same experimental conditions. However, during the experiment, it was found that when the micropore size is too small, for example, when the micropore diameter is less than 20μm, it is easy to cause micropore tube clogging. Therefore, in practical applications, in order to achieve more stable continuous production, a relatively large micropore diameter can be used, such as a micropore diameter of 20μm, 30μm, or 40μm or above.

[0096] Example 12

[0097] In this embodiment, the size of the W / O micro-droplets is adjusted by adjusting the distance (L) between the lower edge of the micro-well and the upper edge of the liquid surface after infiltration.

[0098] This example conducted 11 experiments. In each of these 11 experiments, the distance (L) between the lower edge of the microwell and the upper edge of the liquid surface after infiltration in step (2) was controlled to be 200 μm, 400 μm, 600 μm, 800 μm, 1000 μm, 1200 μm, 1400 μm, 1600 μm, 1800 μm, 2000 μm, and 2200 μm, respectively. Except for the above experimental conditions, the other operations were the same as those in Example 3.

[0099] The monodisperse W / O droplets prepared in 11 groups of experiments in this example were observed using an optical microscope, and the diameters of the W / O droplets were counted. The results are as follows: Figure 5 As shown in the figure. Figure 5Figures a) to c) show the size distribution and optical microscope photos of the monodisperse W / O droplets prepared when the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is 200μm, 600μm, and 1000μm. The average diameter D of the W / O droplets prepared under these three conditions is avg The coefficient of variation CV values ​​of the particle size of W / O microdroplets are 189.25 μm, 1.13%, 340.22 μm, 1.82%, and 516.92 μm, 2.9%, respectively. The particle size distribution range of W / O microdroplets is narrow and has excellent monodispersity. Figure 5 Figure d) shows the relationship between the diameter of the W / O microdroplet and the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration. It can be seen from the figure that the two show a good linear relationship. According to this law, the diameter of the W / O microdroplet can be flexibly controlled in the range of 180 to 1000 μm.

[0100] Example 13

[0101] In this embodiment, W / O microdroplets were prepared using a microporous tube having 9 micropores on a hydrophobic microporous base plate, and the steps were as follows:

[0102] (1) Preparation of dispersed phase and continuous phase

[0103] Deionized water was used as the dispersed phase; the oil-soluble surfactant T154 was dissolved in tetradecane to obtain a continuous phase, and the concentration of T154 in the continuous phase was 0.08 g / mL.

[0104] (2) Preparation of monodisperse W / O microdroplets

[0105] According to the operation in Example 2, the second microporous tube in Example 1 was combined with a collection container in conjunction with an inclined table and a lifting platform to construct a device for controllable preparation of monodisperse microdroplets. The hydrophobic microporous bottom plate of the microporous tube had 9 micropores, each with a diameter of 40 μm. The angle (θ) between the hydrophobic microporous bottom plate of the microporous tube and the horizontal plane was adjusted to 30° by adjusting the inclination of the inclined table.

[0106] In this embodiment, a total of 5 groups of experiments were set up. In the 5 groups of experiments, after the hydrophobic microporous bottom plate was infiltrated with the continuous phase in the collection container, the upper edge of the liquid surface after infiltration was located at the scale line below the micropore (that is, the upper edge of the liquid surface after infiltration coincided with the scale line below the micropore), and the position of the collection container was continued to be adjusted so that the distance (L) between the lower edge of each micropore and the upper edge of the liquid surface after infiltration was constant at 200μm, 400μm, 600μm, 800μm, and 1000μm, respectively.

[0107] The dispersed phase is injected into the microporous tube, passes through the micropores and contacts the continuous phase spread on the hydrophobic microporous bottom plate. The dispersed phase is in the air phase (A)-dispersed phase (W)-continuous phase (O) three-phase interfacial tension difference (γ AW >γ AO +γ WO ) induced by the continuous phase, it spreads on the surface of the dispersed phase droplets passing through the micropores and engulfs the dispersed phase droplets into the continuous phase via "endocytosis," generating monodisperse W / O microdroplets. During this preparation step, the vertical distance from the dispersed phase surface to the micropores was maintained at 40 cm. The angle (θ) between the hydrophobic micropore bottom plate and the horizontal plane was maintained constant at the aforementioned level. The distance (L) between the lower edge of each micropore and the upper edge of the liquid surface after infiltration was also maintained constant at the aforementioned level in each experimental group.

[0108] The monodisperse W / O droplets prepared in the five groups of experiments in this example were observed using an optical microscope, and the W / O droplet diameters and the CV values ​​of the W / O droplet diameters were calculated. Figure 6 As shown in Figure a), increasing the number of micropores on the hydrophobic microporous substrate does not affect the linear relationship between the W / O microdroplet diameter and the distance (L) between the lower edge of each micropore and the upper edge of the liquid surface after infiltration. Furthermore, increasing the number of micropores on the hydrophobic microporous substrate does not affect the monodispersity of the W / O microdroplets, providing experimental evidence for the controllable batch preparation of microdroplets.

[0109] Example 14

[0110] In this example, the effect of the number of micropores on the hydrophobic microporous base plate on the preparation of W / O microdroplets was investigated.

[0111] This example conducted nine experiments. The number of micropores on the hydrophobic microporous base of the microporous tubes used in each experiment ranged from 1 to 9. The distance (L) between the lower edge of each micropore and the upper edge of the liquid surface after infiltration was controlled to be 200 μm. Aside from these differences, all other procedures and experimental conditions were identical to those in Example 13. Ultimately, a series of monodisperse W / O microdroplets were produced.

[0112] Figure 6 Figure b) shows the change in the dispersed phase flow rate and the CV value of the prepared W / O microdroplets when the number of micropores is 1 to 9 in this embodiment. It can be seen from the figure that the flow rate of the dispersed phase shows a linear growth relationship with the increase in the number of micropores, which shows that the process of generating microdroplets from different micropores is independent of each other and does not affect each other under normal working conditions. Moreover, the prepared microdroplets have good monodispersity, which provides an experimental basis for the controllable preparation of microdroplets in batches.

[0113] Example 15

[0114] The operation of this example is basically the same as that of Example 14, except that the vertical distance (h) between the liquid surface of the dispersed phase and the micropores is controlled to be 30 cm during the preparation process of step (2). Finally, a series of monodisperse W / O microdroplets are prepared.

[0115] During the preparation process, the formation process of W / O microdroplets was observed using a high-speed camera. Figure 7 As shown, Figures a) to d) correspond to the cases where the hydrophobic microporous bottom plate has 1, 2, 3 and 9 micropores, respectively.

[0116] This example uses optical microscope photos of W / O microdroplets prepared by microporous tubes with 1, 2, 3, and 9 micropores on a hydrophobic microporous bottom plate, and calculates the average diameter D of the W / O microdroplets. avg The coefficient of variation of the particle size of W / O droplets is CV. Figure 8 As shown in Figures a) to d) of FIG, it can be seen from the figure that the W / O microdroplets prepared in this example have excellent monodispersity, and the CV values ​​do not exceed 1.5%.

[0117] Example 16

[0118] Monodisperse W / O microdroplets are prepared by the method of the present invention, and polyethylene glycol diacrylate (PEGDA) particles are prepared based on the prepared W / O microdroplets, and the steps are as follows:

[0119] (1) Preparation of dispersed phase and continuous phase

[0120] PEGDA was dissolved in water, and then a photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP) was added and mixed thoroughly to obtain a dispersed phase, in which the mass fraction of PEGDA was 47.5% and the mass percentage of the photoinitiator was 5%.

[0121] The oil-soluble surfactant T154 was dissolved in tetradecane to obtain a continuous phase, and the concentration of T154 in the continuous phase was 0.08 g / mL.

[0122] (2) Preparation of monodisperse W / O microdroplets and solidification into PEGDA particles

[0123] Following the procedures described in Example 2, the first microporous tube of Example 1 was combined with a collection container, an inclined table, and a lifting platform to construct an apparatus for controllably preparing monodisperse microdroplets. Specifically, a hydrophobic microporous base with a pore diameter of 40 μm was used. The tilt of the inclined table was adjusted to maintain a 30° angle between the hydrophobic microporous base of the microporous tube and the horizontal plane. After the hydrophobic microporous base and the continuous phase in the collection container were infiltrated, the distance (L) between the lower edge of the micropore and the upper edge of the infiltrated liquid level was 200 μm.

[0124] The dispersed phase is injected into the microporous tube, passes through the micropores and contacts the continuous phase spread on the hydrophobic microporous bottom plate. The dispersed phase is in the air phase (A)-dispersed phase (W)-continuous phase (O) three-phase interfacial tension difference (γ AW >γ AO +γ WO ) induced by the continuous phase, it spreads on the surface of the dispersed phase droplets passing through the micropores and engulfs the dispersed phase droplets into the continuous phase through "endocytosis," generating monodisperse W / O microdroplets. During the W / O microdroplet's descent, UV light is applied to the droplets. Within milliseconds of exposure to UV light, PEGDA polymerizes into particles that fall into a collection container. The particles are then rinsed five times in isopropyl alcohol and five times in pure water to obtain clean PEGDA particles.

[0125] During the preparation process, the vertical distance (h) from the liquid surface of the dispersed phase to the micropores is controlled to be 40 cm, the angle (θ) between the hydrophobic micropore bottom plate and the horizontal plane is controlled to be constant at the aforementioned level, and the distance (L) between the lower edge of the micropores and the upper edge of the liquid surface after infiltration is controlled to be constant at the aforementioned level.

[0126] Figure 9 Figures a) to c) are scanning electron microscope images of the PEGDA particles prepared in this example. It can be seen from the figures that the PEGDA particles prepared in this example have uniform morphology, smooth surface structure and dense interior of the particles.

[0127] Example 17

[0128] In this embodiment, monodisperse W / O microdroplets were prepared using the method of the present invention, and poly (N-isopropylacrylamide) (PNIPAm) particles were prepared based on the prepared W / O microdroplets. The steps are as follows:

[0129] (1) Preparation of dispersed phase and continuous phase

[0130] N-isopropylacrylamide (NIPAm) was dissolved in water, and then a photoinitiator, 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP), and a crosslinker, N,N'-methylenebisacrylamide (BIS), were added and mixed thoroughly to obtain a dispersed phase, in which the mass fraction of NIPAm was 20%, the mass fraction of the photoinitiator was 5%, and the mass fraction of the crosslinker was 2%.

[0131] The oil-soluble surfactant T154 was dissolved in tetradecane to obtain a continuous phase, and the concentration of T154 in the continuous phase was 0.08 g / mL.

[0132] (2) Preparation of monodisperse W / O microdroplets and solidification into PNIPAm particles

[0133] The procedure for this step was the same as step (2) of Example 16, with the only difference being that two sets of experiments were performed in this example, in which the distance (L) between the lower edge of the microwell and the upper edge of the liquid surface after immersion was controlled to be constant at 1400 μm and 400 μm, respectively. The two sets of experiments yielded PNIPAm particles of two different sizes.

[0134] When the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is 1400 μm, the optical micrograph of the prepared PNIPAm particles is as follows: Figure 9 As shown in Figure d), when the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is 400 μm, the optical photograph of the prepared PNIPAm particles is as follows Figure 9 As shown in Figure e), the PNIPAm particles prepared in this example have a uniform morphology and a smooth surface. Furthermore, by adjusting the distance (L) between the lower edge of the micropores and the upper edge of the liquid surface after infiltration, the size of the W / O microdroplets, and thus the size of the resulting solidified microparticles, can be adjusted.

[0135] Example 18

[0136] In this embodiment, monodisperse W / O microdroplets were prepared using the method of the present invention, and polyacrylamide (PAm) particles were prepared based on the prepared W / O microdroplets. The steps are as follows:

[0137] (1) Preparation of dispersed phase and continuous phase

[0138] Acrylamide (Am) was dissolved in water, and then a photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP) and a crosslinker N,N'-methylenebisacrylamide (BIS) were added and mixed thoroughly to obtain a dispersed phase, in which the mass fraction of Am was 10%, the mass fraction of the photoinitiator was 5%, and the mass fraction of the crosslinker was 5%.

[0139] The oil-soluble surfactant T154 was dissolved in tetradecane to obtain a continuous phase, and the concentration of T154 in the continuous phase was 0.08 g / mL.

[0140] (2) Preparation of monodisperse W / O microdroplets and solidification into PAm particles

[0141] The operation of this step was the same as step (2) of Example 16, except that two sets of experiments were conducted in this example. In each set of experiments, the distance (L) between the lower edge of the microwell and the upper edge of the liquid surface after infiltration was controlled to be constant at 800 μm and 600 μm, respectively. The two sets of experiments each produced PAm particles of two different sizes.

[0142] When the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is 800 μm, the optical micrograph of the prepared PAm particles is as follows: Figure 9 As shown in FIG f), when the distance (L) between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is 600 μm, the optical photograph of the prepared PAm particles is as follows Figure 9 As shown in Figure g), the PAm particles prepared in this example have uniform morphology and a smooth surface. Furthermore, by adjusting the distance (L) between the lower edge of the micropores and the upper edge of the liquid surface after infiltration, the size of the W / O microdroplets, and thus the size of the resulting solidified microparticles, can be adjusted.

Claims

1. A method for controllably preparing monodisperse microdroplets based on the principle of wetting, characterized in that: A microporous tube (1) is prepared in combination with a collection container (2). The microporous tube (1) is composed of a dispersed phase containing tube (1-1) and a hydrophobic microporous bottom plate (1-2). The hydrophobic microporous bottom plate (1-2) is a flat plate provided with micropores. The hydrophobic microporous bottom plate (1-2) is fixed to one end of the dispersed phase containing tube (1-1) to seal the one end of the dispersed phase containing tube. The method comprises the following steps: ① Place the continuous phase in a collection container so that the liquid surface of the continuous phase is horizontal. Place the microporous tube above the collection container so that the hydrophobic microporous bottom plate is tilted and the end of the microporous tube with the hydrophobic microporous bottom plate is lower than the end without the hydrophobic microporous bottom plate. Adjust the height of the collection container so that the continuous phase contacts the hydrophobic microporous bottom plate but does not contact the micropores. After the continuous phase contacts the hydrophobic microporous bottom plate, infiltration occurs between the continuous phase and the hydrophobic microporous bottom plate. Continue to adjust the height of the collection container so that the liquid surface after infiltration is below the micropores, and the distance between the lower edge of the micropores and the upper edge of the liquid surface after infiltration ( L ) is 200~2200 μm; ② The dispersed phase is injected into the microporous tube. The dispersed phase passes through the micropores and contacts the continuous phase spread on the hydrophobic microporous bottom plate. Monodisperse microdroplets are generated under the induction of the interfacial tension difference between the air phase, the dispersed phase and the continuous phase. The interfacial tension between the dispersed phase and the continuous phase at the micropore outlet should satisfy γ AW > γ AO + γ WO , γ AW is the interfacial tension between the air phase and the dispersed phase, γ AO is the interfacial tension between the air phase and the continuous phase, γ WO is the interfacial tension between the dispersed phase and the continuous phase; during the preparation process, the vertical distance from the liquid surface of the dispersed phase to the micropores is controlled ( h ) is 20~65 cm, and the angle between the hydrophobic microporous bottom plate and the horizontal plane is controlled ( θ ) is kept constant, and the distance between the lower edge of the micropore and the upper edge of the liquid surface after infiltration is controlled ( L ) remains constant.

2. The method for controllably preparing monodisperse microdroplets based on the wetting principle according to claim 1, characterized in that: The micropores on the hydrophobic microporous bottom plate (1-2) are circular, and the micropore diameter is ( D ) is 20~60 μm.

3. The method for controllably preparing monodisperse microdroplets based on the wetting principle according to claim 2, characterized in that: The number of micropores on the hydrophobic microporous bottom plate (1-2) is at least one; when the number of micropores on the hydrophobic microporous bottom plate (1-2) exceeds one, the micropores are identical and the centers of the micropores are located on the same straight line, and the distance between adjacent micropores is at least 2 μm.

4. The method for controllably preparing monodisperse microdroplets based on the wetting principle according to claim 3, characterized in that: When the number of micropores on the hydrophobic microporous bottom plate (1-2) exceeds 1, the distance between the lower edge of each micropore and the upper edge of the liquid surface after infiltration is controlled in step ① ( L )equal.

5. The method for controllably preparing monodisperse microdroplets based on the wetting principle according to claim 3, characterized in that: The hydrophobic microporous bottom plate (1-2) is provided with a scale line; when the number of micropores on the hydrophobic microporous bottom plate (1-2) is one, the scale line and the diameter of the micropore are parallel to each other; when the number of micropores on the hydrophobic microporous bottom plate (1-2) exceeds one, the scale line and the line connecting the centers of the micropores are parallel to each other.

6. The method for controllably preparing monodisperse microdroplets based on the wetting principle according to any one of claims 1 to 4, characterized in that: The thickness of the hydrophobic microporous bottom plate (1-2) is 0.1-1 mm. The hydrophobic microporous bottom plate (1-2) is made of a material with a hydrophobic surface. The hydrophobic microporous bottom plate (1-2) does not deform during the preparation of monodisperse microdroplets.

7. The method for controllably preparing monodisperse microdroplets based on the wetting principle according to any one of claims 1 to 4, characterized in that: Step ① The tilted setting of the hydrophobic microporous bottom plate refers to the angle between the hydrophobic microporous bottom plate and the horizontal plane ( θ ) is 20°~60°.

8. The method for controllably preparing monodisperse microdroplets based on the wetting principle according to any one of claims 1 to 4, characterized in that: The dispersed phase is an aqueous phase and the continuous phase is an oil phase.

9. The method for controllably preparing monodisperse microdroplets based on the wetting principle according to claim 7, characterized in that: The continuous phase contains an interface stabilizing agent, and the interface stabilizing agent includes a surfactant and / or nanoparticles for stabilizing the interface.

10. The method for controllably preparing monodisperse microdroplets based on the wetting principle according to claim 7, characterized in that: The dispersed phase contains at least one of a functional polymer, a monomer, a thickener, a salt and functional nanoparticles that can be dissolved in an aqueous solvent.

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