Microreactor device and system and application of microreactor device and system in preparation of liquid crystal colloidal particles

Abstract

According to the microreactor device and system and the application of the microreactor device and system in preparation of the liquid crystal colloidal particles, by designing the special structures of the microreactor device and system, liquid crystal topological defects can be used as a programmable nano template for directional assembly and synthesis of the polymer colloidal particles; a liquid crystal center defect point formed in a limited closed system is utilized to assemble a high polymer material into the microspheres with controllable particle size. According to the invention, the characteristics of a single assembly can be researched, or the single assembly can be used as a functional material, such as application in the fields of intelligent photoelectric display, optoelectronic devices, sensing and the like.

Description

Technical Field

[0001] The present invention relates to the field of liquid crystal technology, and in particular to a microreactor device, a system and an application thereof in preparing liquid crystal colloidal particles. Background Art

[0002] Among various soft materials, liquid crystal is one of the most studied stimulus-responsive materials. It has both the fluidity of liquid and the orientation order and optical properties of crystal, and is highly sensitive to external stimuli. Liquid crystal has been quite mature in traditional display application technology, and people have great interest in the research of "beyond" display, and one of the research areas is to manufacture large-scale controllable liquid crystal defect arrays. When the order symmetry in liquid crystal is broken during phase transition or under specific boundary conditions, topological defects will be generated. Due to its fluidity, liquid crystal topological defects are difficult to control, but only when the type and position of defects can be precisely controlled, attractive applications such as colloidal self-assembly, optical vortex, microlens array and bistable display will be realized. Combining liquid crystal with topological defects has become a new method for synthesizing and manipulating particles at the micro-nano scale. Therefore, the precise control of the orientation of liquid crystal molecules has very important research value for both basic research and practical applications.

[0003] Research in the intersection of interface and colloid science has promoted the development of two-dimensional colloidal assemblies, and its applications involve multiple fields, such as chemical and biological sensing, photonics, etc. Studies have shown that a variety of technologies have been developed to prepare two-dimensional colloidal assemblies on solid substrates. The limitation of colloidal assemblies formed on solid substrates is that they are prone to defects and cracks, while assemblies formed on fluid interfaces show the advantages of long-range order and minimal defects. For colloids at the interface of two isotropic fluids (such as water-air), their organizational structure is mainly determined by electrostatic and capillary interactions. In anisotropic systems, liquid crystals can prepare colloidal superstructures with adjustable and external response by introducing additional elastic interactions. However, there are few reports in existing literature on the use of liquid crystals as templates to synthesize microscopic materials. The present invention further develops research in this area. Summary of the invention

[0004] The present invention provides a microreactor device, a system and its application in preparing liquid crystal colloidal particles. By developing a microreactor device with a microstructure, a liquid crystal point defect is formed by using the microstructure center, and the polymer molecules are induced to polymerize toward the defect center by ultraviolet light to prepare colloidal particles. The present invention discloses the process of polymer assembly at the topological defect center formed in the anisotropic material liquid crystal.

[0005] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a microreactor device, comprising a PDMS flexible substrate having a microstructure thereon, wherein the microstructure is a plurality of circular, elliptical, or polygonal holes and grooves having a planar geometric arrangement in cross section.

[0006] Preferably, the planar geometric arrangement is an array arrangement, more preferably a rectangular array arrangement; and / or the polygon is one of a triangle, a rectangle, a pentagon, and a hexagon, and further preferably, the polygon is one of an equilateral triangle, a square, and a regular hexagon; the size of the microstructure is 20~250 μm, and the spacing between the holes and grooves is 20~25 μm.

[0007] Preferably, the device further comprises a cover, and the cover is used to cover the microstructure; more preferably, the cover is a light-transmitting cover.

[0008] In a second aspect, the present invention provides a method for preparing the microreactor device according to the first aspect, comprising the following steps: Step 1, designing a microstructure pattern through a mask; Step 2, transferring the microstructure pattern on the mask to the silicon wafer; Step 3: Transfer the microstructure pattern on the silicon wafer to the PDMS flexible substrate.

[0009] Preferably, in step 2, transferring the microstructure pattern on the mask to the silicon wafer comprises the following steps: Step 2-1: Spin coating is preferably used, with a spin coating speed of 500 rpm and an acceleration of 500 rpm·s -1 , time is 5 s; preferably SU8-3000 series photoresist; Step 2-2: Secondary coating of silicon wafer, preferably by spin coating, with a spin coating speed of 1800-2500 rpm and an acceleration of 1800-2500 rpm·s -1 , time is 60 s; Step 2-3, pre-baking the silicon wafer after the second coating, cooling it to room temperature, stacking the silicon wafer and the mask plate, and then UV-exposing it, and then post-baking the silicon wafer; Step 2-4, developing the silicon wafer, preferably using propylene glycol methyl ether acetate (PGMEA) developer for 4 to 10 minutes; after the development is completed, washing and drying; Step 2-5, further heating the silicon wafer at 120-150° C. for 20-30 min, and cooling to room temperature to obtain a silicon wafer with a microstructure; Further preferably, in step 2-3, the stepwise pre-baking comprises: the first step of heating from room temperature to 50±5°C and keeping for 10-15 min; the second step of heating to 65±5°C and keeping for 10-15 min; the third step of heating to 95±5°C and keeping for 10-15 min; the fourth step of cooling from 95°C to room temperature; and / or, The step-by-step post-baking includes: the first step is heating from room temperature to 50±5℃, and keeping at 50±5℃ for 10 min; the second step is heating from 50±5℃ to 65±5℃, and keeping at 65±5℃ for 10 min; the third step is heating from 65±5℃ to 80±5℃, and keeping at 80±5℃ for 10 min; the fourth step is cooling from 80±5℃ to room temperature; and / or, The control parameters of the UV exposure are: exposure time 25-30 s, UV intensity 120-130 μM·cm -2 .

[0010] Preferably, in step 3, transferring the microstructure pattern on the silicon wafer to the PDMS flexible substrate comprises the following steps: Step 3-1, mold pouring: polydimethylsiloxane (PDMS) and curing agent are mixed in a mass ratio of 10:1 and bubbles are eliminated to obtain liquid PDMS; Step 3-2, covering the liquid PDMS on the silicon wafer and performing thermal curing. Preferably, the curing parameters include: temperature 80-90°C, time 30-40 min, and cooling to room temperature; after the curing is completed, the PDMS is peeled off from the silicon wafer to obtain a PDMS flexible substrate with a microstructure.

[0011] In a third aspect, the present invention provides a micro-reaction system, comprising the micro-reactor device described in the first aspect and a fluid delivery device, wherein the fluid delivery device is used to deliver fluid to the microstructure of the micro-reactor device.

[0012] Preferably, the fluid delivery device comprises a glass capillary, the glass capillary is fixed on a displacement platform, and the displacement platform is used to drive the glass capillary to move in the XYZ axis direction; one end of the glass capillary is connected to the injection device.

[0013] In a fourth aspect, the present invention provides a method for preparing liquid crystal colloidal particles, which adopts the micro-reaction system described in the third aspect, wherein the microstructure of the microreactor device is an equilateral triangle, and the microreactor device further includes a cover for covering the microstructure, wherein the cover is a light-transmitting cover; and comprises the following steps: (1) preparing a liquid crystal mixture fluid, adding the liquid crystal mixture fluid into a microstructure of a microreactor device through a fluid delivery device, and sealing the microstructure with a cover; (2) The microreactor device is placed under ultraviolet light to obtain liquid crystal colloidal particles.

[0014] Preferably, the microstructure has a depth of >40 μm and a side length of 60-80 μm; and / or, The ultraviolet light has a wavelength of 365 nm; and / or, The preparation method of the liquid crystal mixture fluid comprises: mixing the monomer HEMA and the photoinitiator HMP in a volume ratio of 10:1-2 to prepare a precursor, and then mixing the precursor with 5CB, wherein the volume proportion of the 5CB in the system is preferably 93-97%.

[0015] In a fifth aspect, the present invention provides liquid crystal colloidal particles obtained by the preparation method described in the fourth aspect.

[0016] In a sixth aspect, the present invention provides the use of the liquid crystal colloidal particles described in the fifth aspect in the preparation of liquid crystal products, anti-counterfeiting products or chemical sensors.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a new method for directional assembly and synthesis of polymer colloidal particles using liquid crystal topological defects as programmable nano-templates. The central defect points of the liquid crystal formed in a confined closed system are used to assemble polymer materials into microspheres with controllable particle sizes. The advantages are that the operation process is simple, the PDMS (polydimethylsiloxane) substrate does not require any surface treatment, the microstructure confinement can form a regular array of liquid crystal defects, and the particles can be synthesized in situ in one step with good monodispersity. Unlike previous polymer assembly studies conducted in isotropic solutions, the introduction of defects in liquid crystals can accurately control the position of polymer assembly. The present invention is helpful for studying the properties of a single assembly or using a single assembly as a functional material, such as in the fields of intelligent optoelectronic displays, optoelectronic devices, and sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of the microreactor device of the present invention, wherein: 1-PDMS flexible substrate, 2-microstructure, 3-cover.

[0019] Figure 2 These are the microstructure design drawings of different geometric shapes (Figures A~D) in step (2) of Example 1.

[0020] Figure 3 The mask design drawing of step (1) in Example 1 includes Figure 2 Microstructures of different sizes and shapes.

[0021] Figure 4 Polarized optical microscope images of the liquid crystal mixture filled side view of Example 2 (Figure A), HEMA-5CB anchored in air (Figure B) and PVA (Figure C).

[0022] Figure 5 These are microscope images of Example 3 at different volume ratios of HEMA and 5CB under polarized light (Figures A~G).

[0023] Figure 6 This is the DSC curve when HEMA and 5CB are mixed at different volume ratios in Example 3.

[0024] Figure 7 These are microscope images of colloidal particles formed at different volume ratios of HEMA and 5CB (Figures A to E) under bright field in Example 3.

[0025] Figure 8 Bright field microscopy images of colloidal particles formed in micropores with different geometric structures (Figures A~D) after ultraviolet illumination in Example 4.

[0026] Fig. 9 These are microscope images of colloidal particles formed by illumination with different UV wavelengths under bright field in Example 5 (Figures A~B).

[0027] Fig.10 This is a microscope image of colloidal particles of different microstructure sizes formed in Example 6 under bright field.

[0028] Fig.11 This is the morphology of the colloidal particles obtained by the 53×70 μm combination in Example 6. DETAILED DESCRIPTION

[0029] The XYZ displacement platform used in the embodiment of the present invention is specifically an XYZ three-axis precision displacement stage, model LD80, manufactured by Paidiwei. Other commercially available devices that can realize the movement of the capillary in the three directions of XYZ can be used in the present invention.

[0030] If no specific conditions are specified in the examples of the present invention, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0031] The present invention provides a microreactor device, the structure of which is as follows: Figure 1 As shown, the device includes a PDMS flexible substrate 1, and a microstructure 2 is provided on the PDMS flexible substrate 1. The microstructure 2 is a plurality of circular, elliptical, or polygonal holes and grooves with a planar geometric arrangement in cross section. In the microstructure, the polygon is one of a triangle, a rectangle, a pentagon, and a hexagon. For example, the microstructure 2 is a cylinder, an elliptical cylinder, or a polygonal prism (triangular prism, cube, pentagonal prism, hexagonal prism, etc.).

[0032] In a preferred embodiment of the present invention, the microreactor device further comprises a cover 3, which is used to cover the microstructure to better perform the relevant reaction. More preferably, a light-transmitting cover such as a glass slide is selected, which can allow light to occur while playing a sealing role. If light protection is required, light-shielding material can be sealed on the light-transmitting cover, such as black paper, to achieve light protection.

[0033] In a preferred embodiment of the present invention, the polygon is one of a regular triangle, a square, and a regular hexagon. The size of the microstructure is 20-250 μm, and the spacing between the holes and grooves is 20-25 μm.

[0034] In a preferred embodiment of the present invention, the planar geometric arrangement is an array arrangement, such as a ring array arrangement, a circular array arrangement, an elliptical array arrangement, a rectangular array arrangement, and more preferably a rectangular array arrangement. In the rectangular array arrangement, there are also various forms, such as Figure 2 The two situations shown can also be a rectangular array structure, with the two opposite sides being a "concave" or "convex" shaped structure, or the two opposite sides being a smooth arc structure with an arc angle of 30~150°, and so on.

[0035] Furthermore, the following embodiments of the present invention are described in detail using preferred equilateral triangle, square, and regular hexagonal microstructures as examples, wherein when the hole groove is circular, the size is defined by diameter and depth; when the hole groove is an equilateral triangle and a square, the size is defined by side length and depth; when the hole groove is a regular hexagon, the size is defined by the circumscribed circle diameter and depth.

[0036] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, which are intended to explain the present invention rather than to limit it. Example 1 Fabrication of an array of PDMS flexible microstructure arrays

[0037] This embodiment provides a process for manufacturing a PDMS flexible substrate with a microstructure, comprising the following steps: (1) Use AutoCAD software to draw geometric patterns of different sizes and shapes and customize them into masks with a size of 5 inches × 5 inches × 2.3 mm. Figure 3 The mask design of the microstructure is shown, black indicates opaque, and white indicates transparent. The microstructure size is 20~250 μm, and the spacing between adjacent unit microstructures is 20~25 μm. Figure 2 Detailed images of four types of microstructure masks produced in this embodiment are shown. These four types of microstructures are arranged in a square array, and the opposite sides are parallel straight-line or curved structures.

[0038] (2) Photolithography microstructure process: Glue coating: SU8-3000 series photoresist is used for spin coating on silicon wafers. The spin coating is divided into two steps. The first step is: speed 500 rpm, acceleration 500 rpm·s -1 , time 5 s; the second step of spin coating: speed 1800~2500 rpm, acceleration 1800~2500 rpm·s -1 , time 60 s, spin coating thickness is about 20~60 μm; then step-by-step pre-baking is performed and naturally cooled to room temperature; the mask is aligned with the silicon wafer coated with glue in the photolithography machine for UV exposure, and the UV exposure parameters are: exposure time 25 s, UV intensity 126 μM·cm -2 ; Then carry out post-baking in steps; Development: Use PGMEA developer for 4 to 10 min; After development, wash with isopropyl alcohol, blow dry the silicon wafer with nitrogen and observe the photolithography under a microscope; Harden the film: Place the photolithographic silicon wafer on a 120 ℃ hot plate for 30 min, and then cool it naturally to room temperature.

[0039] In the above process, the step-by-step pre-baking includes: the first step is heating from room temperature to 50±5℃ and keeping it for 10~15 min; the second step is heating to 65±5℃ and keeping it for 10~15 min; the third step is heating to 95±5℃ and keeping it for 10~15 min; the fourth step is cooling from 95℃ to room temperature.

[0040] The step-by-step post-baking includes: the first step is heating from room temperature to 50±5℃, and maintaining at 50±5℃ for 10 min; the second step is heating from 50±5℃ to 65±5℃, and maintaining at 65±5℃ for 10 min; the third step is heating from 65±5℃ to 80±5℃, and maintaining at 80±5℃ for 10 min; the fourth step is cooling from 80±5℃ to room temperature.

[0041] (3) PDMS mold pouring: PDMS and curing agent are fully stirred and mixed in a mass ratio of 10:1, and then vacuum is used to eliminate bubbles to obtain liquid PDMS; the liquid PDMS is then evenly poured on the silicon wafer and thermally cured. The curing parameters include: temperature 90 °C, time 30 min, and natural cooling to room temperature; after the curing is completed, the PDMS is peeled off the silicon wafer, cut and stored for later use. Example 2 Construction of Liquid Crystal Micro-Reaction System

[0042] The present embodiment provides a liquid crystal micro-reaction system, comprising a PDMS flexible substrate (i.e., a microreactor device) having a microstructure manufactured in the manner of Embodiment 1, wherein the microstructure has a depth of 20 to 60 μm, a side length of 20 to 250 μm, and a spacing between adjacent unit microstructures of 20 to 25 μm; the system further comprises a fluid conveying device, which is used to convey fluid into the microstructure of the microreactor device.

[0043] The specific construction method of the liquid crystal micro-reaction system is as follows: (1) Construction of the fluid delivery device: The fluid delivery device consists of an XYZ displacement platform and a glass capillary. Use a silicone hose to connect the 25 μL syringe and the capillary, inject the liquid crystal mixture into the capillary, and then fix the capillary on the XYZ displacement platform. Adjust the position of the capillary to the top of the microstructure, and fill the liquid crystal mixture into the microstructure along the wall ( Figure 4 Figure A in the middle shows a schematic diagram of the filling of the triangular prism microstructure). The XYZ displacement platform axis can be adjusted to control the position of the capillary to achieve the filling of the microwell at any position in the array. Figure 4 Figure A in the middle also shows a bright field microscope image of the liquid crystal mixture filling the PDMS microwells.

[0044] The preparation method of the liquid crystal mixture fluid comprises: mixing the monomer HEMA and the photoinitiator HMP in a volume ratio of 10:1 to prepare a precursor, and then mixing the precursor with 5CB, wherein the volume ratio of the 5CB in the system is 95%. This embodiment is only a preferred example, and the volume ratio of the monomer HEMA and the photoinitiator HMP can also be 10:1.1, 10:1.2, 10:1.3, 10:1.4, 10:1.5, 10:1.6, 10:1.7, 10:1.8, 10:1.9, 10:2.0, that is, between 10:1 and 2, and the volume ratio of 5CB in the system can be 93-97%.

[0045] (2) Taking the regular triangular prism microstructure as an example, its size information is: depth 44 μm, side length 70 μm, microstructure spacing 20 μm, PVA glass slide is covered on top of the PDMS microstructure, and the change of liquid crystal defect type is observed under a polarizing microscope. The liquid crystal molecules under air anchoring undergo bending deformation (m = -1), while PVA can anchor the liquid crystal molecules in parallel to form a windmill-like texture. The liquid crystal molecules undergo bending deformation along the defect point (m = +1). The texture images are as follows: Figure 4 As shown in Figures B and C. In addition, Figure 4 In Figure C, there is a point at the center of the triangle, which is formed by the intersection of three black lines extending from the three vertices of the triangle to the center. It is also called the defect center. When irradiated with ultraviolet light, the colloidal particles will gather at the defect center. Example 3 Effect of the Precursor and Liquid Crystal Mixing Ratio on Liquid Crystal Phase and Particle Morphology

[0046] (1) Experiment to investigate the effect on the liquid crystal phase: A micro-reaction system was constructed in the manner of Example 2. The microstructure used was a cubic structure with a square cross-section, a side length of 150 μm, a depth of 26 μm, and a microstructure spacing of 20 μm. The structure is as follows: Figure 2As shown in Figure C, the effect of the mixture of precursor and 5CB on the initial phase state of liquid crystal is investigated. First, the monomer HEMA (hydroxyethyl methacrylate) and the photoinitiator HMP (α-hydroxyisobutyrophenyl) are mixed in a volume ratio of 10:1 to prepare a precursor. Secondly, the precursor is mixed with 5CB (4-cyano-4'-pentylbiphenyl) to obtain a liquid crystal mixture fluid. The volume proportion of the mixed precursor is selected as: 3 vol%, 5 vol%, 7 vol%, 9 vol%, 11 vol%, 15 vol%, and the corresponding volume proportion of 5CB is: 97 vol%, 95 vol%, 93 vol%, 91 vol%, 89 vol%, 85 vol%. As shown in Figure C, the mixture of precursor and 5CB has a volume proportion of 97 vol%, 95 vol%, 93 vol%, 91 vol%, 89 vol%, 85 vol%. Figure 5 As shown in the figure, when the volume percentage of 5CB is 85vol%, 89vol%, and 91vol%, it is dark under polarizing microscope observation, showing isotropy. When the volume percentage of 5CB is 93vol%, 95vol%, and 97vol%, it is anisotropic, and the phase transition temperatures measured by differential scanning calorimeter (DSC) are 14.15℃, 19.97℃, and 26.56℃, respectively. Figure 6 ), and it appears as a bright image under polarizing microscope.

[0047] (2) Experiment to investigate the effect on particle morphology: The difference from (1) is that a regular triangular prism microstructure is used with a side length of 70 μm, a depth of 53 μm, and a microstructure spacing of 20 μm. Figure 2 As shown in Figure B, the effect of different volume ratios of precursor and liquid crystal on the formation of polymer particles is investigated (e.g. Figure 7 As shown, Figure 7 The results show that when the precursor ratio is high (>7 vol%), the micropores are easily aggregated into multiple small spherical particles with different shapes; while when the precursor ratio is low (<3 vol%), the content is too low to form polymer spheres, and finally the precursor ratio of 5 vol% was selected. Example 4 Effect of microstructure shape on colloidal particle formation

[0048] A micro-reaction system was built in the manner of Example 2 to explore the effect of microstructure shape on the formation of colloidal particles. A liquid crystal mixture containing 5 vol% of the precursor was filled in a microstructure array with a depth of 53 μm, a diameter or side length of 60, 70, and 80 μm, and a geometric configuration of a circular cross-section (cylinder), a regular triangle (regular triangular prism), a square (a rectangular parallelepiped with a square cross-section), and a regular hexagon (regular hexagonal prism). The PDMS microstructure was covered with a PVA glass slide. A wavelength of 365 nm ultraviolet light was selected for 10 h to observe the effect of changes in the microstructure geometry on the aggregation of colloidal particles. Figure 8(The figure shows a diameter or side length of 70 μm, and the results of other sizes are exactly the same as this figure) It can be seen that colloidal particles are formed only at the original defect point position in the regular triangular prism microstructure, while no particle formation is observed in microstructures of other shapes. Example 5 Effect of UV wavelength on colloidal particle formation

[0049] The micro-reaction system was constructed in the manner of Example 2. The microstructure used was a regular triangular prism (side length 80 μm, depth 53 μm, spacing 20 μm), and its structure was as follows: Figure 2 As shown in Figure B, the effect of UV wavelength on the assembly of colloidal particles was investigated. The sample was placed in a dark room, with the UV lamp 4 cm away from the sample. Two wavelengths of UV light, 254 nm and 365 nm, were selected for irradiation for 10 hours. The effect of different UV wavelengths on the aggregation of colloidal particles in the micropores was observed under a microscope. Fig. 9 As shown, for 254 nm ultraviolet light, the energy is too high, and the polymer molecules are solidified before they move to the center of the microstructure; while 365 nm ultraviolet light is more conducive to the formation of colloidal particles. Example 6 Effect of microstructure size on colloidal particle formation

[0050] The micro-reaction system was constructed in the manner of Example 2, and a triangular prism microstructure was selected and the effect of the microstructure depth (26 μm, 44 μm, 53 μm) and the side length (60 μm, 70 μm, 80 μm) on the formation of colloidal particles was investigated under 365 nm ultraviolet wavelength illumination. The specific combination method is as follows: Fig.10 As shown. After 10 h of UV irradiation, the formation of polymer beads was observed under the bright field mode of the microscope. Fig.11 As shown in the figure, the results show that when the microstructure depth is >40 μm, for example, when the depth is 44-53 μm and the side length is 60-80 μm, polymer spheres will be formed at the defect points. No particles were observed in the microstructure with a depth of 26 μm, indicating that too large or too small size will affect the polymerization effect of colloidal particles. Therefore, for the formation process of colloidal particles, a triangular prism microstructure with a depth of >40 μm and a side length of 60-80 μm is suitable.

[0051] In summary, the present invention provides a microreactor device and a microreaction system, and explores new technologies of the microreactor device and the microreaction system in using liquid crystal topological defects as programmable nanotemplates for directional assembly and synthesis of polymer colloidal particles. The technology assembles polymer materials into microspheres with controllable particle sizes through the central defect points of liquid crystals formed in a confined closed system, which is helpful for studying the characteristics of a single assembly or using a single assembly as a functional material, and is expected to be developed into liquid crystal products, anti-counterfeiting products, chemical sensors, etc., and applied in the fields of intelligent optoelectronic displays, optoelectronic devices and sensors.

[0052] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A microreactor device, characterized in that The invention comprises a PDMS flexible substrate, on which a microstructure is provided. The microstructure is a plurality of circular, elliptical or polygonal holes and grooves with a planar geometric arrangement in cross section.

2. The microreactor device according to claim 1, characterized in that The planar geometric arrangement is an array arrangement, preferably a rectangular array arrangement; and / or the polygon is one of a triangle, a rectangle, a pentagon, and a hexagon, preferably, the polygon is one of an equilateral triangle, a square, and a regular hexagon; the size of the microstructure is 20~250 μm, and the spacing between the holes and grooves is 20~25 μm.

3. The microreactor device according to claim 1 or 2, characterized in that: It also includes a cover, which is used to cover the microstructure; preferably, the cover is a light-transmitting cover.

4. The method for preparing the microreactor device according to any one of claims 1 to 3, characterized in that: The steps include: Step 1, designing a microstructure pattern through a mask; Step 2, transferring the microstructure pattern on the mask to the silicon wafer; Step 3: Transfer the microstructure pattern on the silicon wafer to the PDMS flexible substrate.

5. The preparation method according to claim 4, characterized in that: In step 2, transferring the microstructure pattern on the mask to the silicon wafer comprises the following steps: Step 2-1: Spin coating is preferably used, with a spin coating speed of 500 rpm and an acceleration of 500 rpm·s -1 , time is 5 s; preferably SU8-3000 series photoresist; Step 2-2: Secondary coating of silicon wafer, preferably by spin coating, with a spin coating speed of 1800-2500 rpm and an acceleration of 1800-2500 rpm·s -1 , time is 60 s; Step 2-3, pre-baking the silicon wafer after the second coating, cooling it to room temperature, stacking the silicon wafer and the mask plate, and then UV-exposing it, and then post-baking the silicon wafer; Step 2-4, developing the silicon wafer, preferably using PGMEA developer for 4 to 10 minutes; cleaning and drying after development; Step 2-5, further heating the silicon wafer at 120-150° C. for 20-30 min, and cooling to room temperature to obtain a silicon wafer with a microstructure; Preferably, in step 2-3, the stepwise pre-baking comprises: the first step of heating from room temperature to 50±5°C and keeping for 10-15 min; the second step of heating to 65±5°C and keeping for 10-15 min; the third step of heating to 95±5°C and keeping for 10-15 min; the fourth step of cooling from 95°C to room temperature; and / or, The step-by-step post-baking includes: the first step is heating from room temperature to 50±5℃, and keeping at 50±5℃ for 10 min; the second step is heating from 50±5℃ to 65±5℃, and keeping at 65±5℃ for 10 min; the third step is heating from 65±5℃ to 80±5℃, and keeping at 80±5℃ for 10 min; the fourth step is cooling from 80±5℃ to room temperature; and / or, The control parameters of the UV exposure are: exposure time 25-30 s, UV intensity 120-130 μM·cm -2 .

6. The preparation method according to claim 4 or 5, characterized in that: In step 3, transferring the microstructure pattern on the silicon wafer to the PDMS flexible substrate comprises the following steps: Step 3-1, mold pouring: PDMS and curing agent are mixed in a mass ratio of 10:1 and bubbles are eliminated to obtain liquid PDMS; Step 3-2, covering the liquid PDMS on the silicon wafer and performing thermal curing. Preferably, the curing parameters include: temperature 80-90°C, time 30-40 min, and cooling to room temperature; after the curing is completed, the PDMS is peeled off from the silicon wafer to obtain a PDMS flexible substrate with a microstructure.

7. A micro-reaction system, characterized in that: It comprises the microreactor device according to any one of claims 1 to 3 and a fluid delivery device, wherein the fluid delivery device is used to deliver fluid to the microstructure of the microreactor device.

8. The micro-reaction system according to claim 7, characterized in that: The fluid delivery device comprises a glass capillary, which is fixed on a displacement platform, and the displacement platform is used to drive the glass capillary to move in the XYZ axis direction; one end of the glass capillary is connected to an injection device.

9. A method for preparing liquid crystal colloidal particles, characterized in that: The microreactor system according to claim 7 or 8 is adopted, wherein the microstructure of the microreactor device is an equilateral triangle, and the microreactor device further comprises a cover for covering the microstructure, wherein the cover is a light-transmitting cover; and the steps are as follows: (1) preparing a liquid crystal mixture fluid, adding the liquid crystal mixture fluid into a microstructure of a microreactor device through a fluid delivery device, and sealing the microstructure with a cover; (2) The microreactor device is placed under ultraviolet light to obtain liquid crystal colloidal particles.

10. The method for preparing liquid crystal colloidal particles according to claim 9, characterized in that: The microstructure has a depth of >40 μm and a side length of 60-80 μm; and / or, The ultraviolet light has a wavelength of 365 nm; and / or, The preparation method of the liquid crystal mixture fluid comprises: mixing the monomer HEMA and the photoinitiator HMP in a volume ratio of 10:1-2 to prepare a precursor, and then mixing the precursor with 5CB, wherein the volume proportion of the 5CB in the system is preferably 93-97%.

11. Liquid crystal colloidal particles obtained by the preparation method according to claim 9 or 10.

12. Use of the liquid crystal colloidal particles according to claim 11 in preparing liquid crystal products, anti-counterfeiting products or chemical sensors.

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