A bio-based microcapsule, and a preparation method and application thereof

Abstract

The application discloses a kind of bio-based microcapsules and its preparation method and application, belong to concrete self-repairing material technical field.The bio-based microcapsules prepared by the application is composed of capsule core and capsule wall, and the capsule core is mineral oil, and the capsule wall raw material is acrylate mixture;Based on microfluidic technology, the bio-based microcapsules is prepared, and the properties are uniform and the structure is stable, with good sphericity and monodispersity.The bio-based microcapsules is applied to prepare self-repairing concrete, and the bio-based microcapsules can repair concrete cracks, and can improve the compressive strength of concrete, enhance its bearing capacity and durability;Soybean oil epoxidized acrylate is derived from renewable resource soybean oil, with biodegradability and environmental protection, which helps to reduce pollution and damage to the environment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete self-repairing materials, and particularly relates to a bio-based microcapsule and a preparation method and application thereof. BACKGROUND

[0002] With the continuous advancement of China's transportation infrastructure construction, the transportation industry is rapidly growing, and the mileage of high-grade highway construction is continuously increasing. Cement concrete pavement has good development prospects due to its high strength, good durability, and benefits for night driving. Although the compressive strength of cement concrete is very high, it is a typical brittle material, and the tensile strength is only about one-tenth of the compressive strength. Under the combined action of load, environmental factors, construction conditions, and maintenance level, cement concrete will appear micro-cracking, leading to a decrease in mechanical and durability performance. Moreover, as the micro-cracking develops, the final crack will merge into a through crack, and rainwater will enter the internal system of the pavement through the through crack, thereby causing diseases such as pumping, settlement, wrong table, and broken board. In addition, under the influence of today's heavy traffic and harsh climate environment, when the cement concrete pavement has cracks, the disease will develop rapidly. Moreover, due to its high strength, cement concrete pavement is difficult to repair, and special machinery and repair materials are required. The long maintenance period also causes many disturbances to traffic, affecting the road capacity. Traditional post-maintenance can repair visible cracks, but it cannot meet the higher demand for cement concrete in today's society. Self-repairing concrete can repair the micro-cracking in the internal cement concrete at an early stage, prevent the further expansion of micro-cracks, and prolong the service life of the cement concrete structure. It is a development trend in the field of cement concrete materials.

[0003] At present, the microencapsulation of self-repairing materials for cement-based materials generally uses in-situ polymerization and interfacial polymerization methods. The use of in-situ polymerization to prepare microcapsules has the difficulty of selecting initiators, and the polymerization reaction is not easy to intervene manually. At the same time, the post-treatment of the reaction solution is relatively complex and may involve tedious separation and purification steps. The utilization rate of the interfacial polymerization equipment is relatively low, and it is difficult to control the final product due to the fast reaction speed. These traditional preparation methods have the same shortcomings, and the operation process is relatively complex, often accompanied by vigorous mechanical stirring, which makes it difficult to unify the size and structure of the generated microcapsules, and it is difficult to deeply explore the influence of the size and structure of the microcapsules on the mechanical properties and self-repairing properties of cement-based materials.

[0004] The self-repairing microcapsules with acrylate as the capsule wall in the prior art are usually prepared by reacting acrylate and alcohol under catalytic conditions, and the acrylate is usually derived from fossil fuel propylene; although acrylate is a suitable shell material in terms of material performance, the preparation process consumes fossil fuels, which in turn leads to the intensification of the greenhouse effect, and the large-scale production of microcapsules in the field of civil engineering for road cracks, so it is particularly important to find a bio-based microcapsule material. SUMMARY

[0005] In view of the above prior art, the present application discloses a bio-based microcapsule and a preparation method and application thereof, to solve the technical problems of the prior art, such as complex operation, non-environmental raw materials, and difficult to unify the size and structure of the prepared microcapsule material, poor self-repairing effect, etc.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is to provide a bio-based microcapsule, which is composed of a capsule core and a capsule wall, and the capsule core is mineral oil; the raw material of the capsule wall is an acrylate mixture; the acrylate mixture is prepared by the following method: adding soybean oil epoxidized acrylate (AESO) into isobornyl acrylate (IBOA) solution to obtain a soybean oil epoxidized acrylate-isobornyl acrylate mixed solution, and then adding a photoinitiator to the soybean oil epoxidized acrylate-isobornyl acrylate mixed solution.

[0007] On the basis of the above technical scheme, the present application can also be improved as follows.

[0008] Further, the solvent of the isobornyl acrylate solution is ethyl acetate, diethyl ether or ethanol, and the concentration of the isobornyl acrylate solution is 75wt%; the photoinitiator is a methylpropanoyl phenone solution with a concentration of 5wt%, and the solvent of the methylpropanoyl phenone solution is ethyl acetate, diethyl ether or ethanol.

[0009] Further, the soybean oil epoxidized acrylate-isobornyl acrylate-acrylate mixture includes 1 part of soybean oil epoxidized acrylate, 3 parts of isobornyl acrylate solution and 1 part of photoinitiator by weight.

[0010] The present application also discloses a preparation method of the above bio-based microcapsule, which comprises the following steps:

[0011] S1: nest the tapered outlet of the inner phase capillary glass tube in the middle phase capillary glass tube, the nesting depth is 100 μm; then nest the tapered outlet of the middle phase capillary glass tube in the outer phase capillary glass tube, the nesting depth is 100 μm, and set the auxiliary system at the inlet of the inner phase capillary glass tube, the middle phase capillary glass tube and the outer phase capillary glass tube respectively, to complete the construction of the microfluidic device;

[0012] S2: inject the mineral oil into the inner phase capillary glass tube at a flow rate of 15-35 μL / min, inject the acrylate mixture into the middle phase capillary glass tube at a flow rate of 45-55 μL / min, and inject the polyvinyl alcohol solution with a concentration of 5-15 wt% into the outer phase capillary glass tube at a flow rate of 350-550 μL / min, to collect the emulsion droplets formed at the bottom end of the outer phase capillary glass tube with the polyvinyl alcohol aqueous solution;

[0013] S3: after polymerization, washing and drying of the emulsion droplets, the bio-based microcapsules are obtained; the polymerization condition is to irradiate the emulsion droplets with ultraviolet light, the power of the ultraviolet lamp is 400 W, and the irradiation time is 5-6 min; the drying temperature is 100-150 ℃, and the drying time is 8-12 h.

[0014] On the basis of the above technical solutions, the application can also be improved as follows.

[0015] Further, in step S1, the diameter of the tapered outlet of the inner phase capillary glass tube is 100-200 μm; the diameter of the tapered outlet of the middle phase capillary glass tube is 200-300 μm; and the outer diameter of the outer phase capillary glass tube is 500 μm, and the inner diameter is 400 μm.

[0016] Further, in step S2, the solvent of the polyvinyl alcohol solution is methanol.

[0017] Further, in step S2, the concentration of the polyvinyl alcohol aqueous solution is 5 wt%.

[0018] Further, in step S3, the washing method is to wash with deionized water for 5-7 times.

[0019] The application also discloses the application of the bio-based microcapsules in the preparation of self-repairing concrete.

[0020] The application has the following advantages:

[0021] 1. The bio-based microcapsules prepared in the application have uniform properties and stable structure, and also have good sphericity and monodispersity, and at the microscale, the particle size of the microcapsules is less than 100 μm, which can promote the dispersion between cement particles, reduce the compressive strength and flexural strength of concrete, and can be applied to the construction of bridge pavement, highway pavement semi-rigid base and other engineering fields.

[0022] 2. When the bio-based microcapsules of this invention are applied to the preparation of self-healing concrete, the capsule wall materials of the prepared bio-based microcapsules include soybean oil epoxidized acrylate, isoborneol acrylate, and a photoinitiator. The photoinitiator, upon receiving ultraviolet quanta emitted by a strong ultraviolet lamp, initiates a polymerization reaction, and the mixture solidifies into a solid state, effectively encapsulating the core of the bio-based microcapsule. This allows the core to repair cracks after subsequent release. Soybean oil epoxidized acrylate possesses lubricating and penetrating properties, while isoborneol acrylate enhances the strength and toughness of the polymer. The synergistic effect of epoxidized soybean oil acrylate and isoborneol acrylate significantly improves the toughness of the microcapsules. The properties of the microcapsule help improve its rupture performance, ensuring its integrity during mixing with cement. Simultaneously, the microcapsule shell possesses sufficiently low tensile strength to promote rupture within the cement matrix when it coincides with a propagating crack. When the concrete crack extends to the location of this bio-based microcapsule, its capsule wall ruptures, releasing the core components for repair. The capsule wall exhibits good flexibility and elasticity, buffering the impact of crack propagation, extending the microcapsule's lifespan, and enhancing its repair effect. Furthermore, soybean oil epoxidized acrylate, derived from renewable soybean oil, is biodegradable and environmentally friendly, helping to reduce environmental pollution and damage.

[0023] 3. The core of the bio-based microcapsules prepared in this invention is mineral oil. Mineral oil has good lubricity and permeability, and can quickly penetrate into the tiny gaps in road surface cracks, which helps to repair the cracks and further enhance the load-bearing capacity of the road surface. At the same time, mineral oil can be stored for a long time in the service environment of cement-based materials. It has a low volume shrinkage rate when it polymerizes, low viscosity and easy flow, adapts to the alkaline environment inside cement-based materials, and has strong durability. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a microfluidic device.

[0025] Figure 2 Microscopic images of the bio-based microcapsules prepared in Example 1;

[0026] Among them, 1. inner phase capillary glass tube; 2. middle phase capillary glass tube; 3. outer phase capillary glass tube; 4. microfluidic chip; 5. syringe; 6. injection pump; 7. dispensing needle; 8. PE tube; 9. light source; 10. microscope lens; 11. high-speed camera; 12. computer; 13. collection bottle. Detailed Implementation

[0027] The microfluidic device structure used in this invention is as follows: Figure 1As shown, including microfluidic chip 4, injection system, photographic system and collection bottle 13. Among them, for the flow control chip 4 includes a substrate and a capillary glass tube arranged on the substrate, the capillary glass tube includes inner phase capillary glass tube 1, middle phase capillary glass tube 2 and outer phase capillary glass tube 3, the inner phase capillary glass tube 1 is nested in the middle phase capillary glass tube 2, the middle phase capillary glass tube 2 is nested in the outer phase capillary glass tube 3, and the three capillary glass tubes are located on a straight line after centering; the inlet of the inner phase capillary glass tube 1, the middle phase capillary glass tube 2 and the outer phase capillary glass tube 3 is provided with an injection system, the injection system includes a syringe pump 6 and a syringe 5, the outlet of the syringe 5 is connected with a PE pipe 8 through a dispensing needle 7, and the tail end of the PE pipe 8 is fixed to the inlet of the capillary glass tube through the dispensing needle 7; the photographic system includes a computer 12 and a high-speed camera 11 provided with a microscope lens 10, the high-speed camera 11 is remotely controlled and set through high-speed camera control software installed in the computer 12; when preparing the droplet, the microscope lens 10 of the high-speed camera 11 is used to observe the real-time situation of droplet generation and make corresponding adjustment, and the droplet is photographed after the generation is stable by adjusting the frame rate per second, exposure time and light source brightness of the high-speed camera 11 and other shooting parameters.

[0028] The specific embodiments of the application will be described in detail below with reference to the examples.

[0029] Example 1

[0030] A method for preparing a bio-based microcapsule, the method comprising the steps of:

[0031] ①Preparation of acrylate mixture

[0032] According to weight parts, 1 part of AESO is added to 3 parts of IBOA solution with a concentration of 75wt% (solvent is ethanol), and after uniform mixing, an AESO-IBOA mixed solution is obtained, then 1 part of methylpropionyl phenone solution with a concentration of 0.5wt% (solvent is ethanol) is added to the AESO-IBOA mixed solution, and the preparation is completed.

[0033] ②Preparation of bio-based microcapsule

[0034] S1: select two original capillary round glass tubes which have not been drawn, one end of one of the tubes is polished to a taper with 2500 grit sandpaper, the diameter of the tapered outlet is 150 μm and the tapered outlet tip is flat and has no gap, this capillary round glass tube is used as the inner phase capillary glass tube 1; the other end of the other tube is polished to a taper with 2000 grit sandpaper, the diameter of the tapered outlet is 250 μm and the tapered outlet tip is flat and has no gap, this capillary round glass tube is used as the middle phase capillary glass tube 2; select another original capillary round glass tube which has not been drawn, the outer diameter is 500 μm and the inner diameter is 400 μm, this capillary round glass tube is used as the outer phase capillary glass tube 3; under a microscope, nest the tapered outlet of the middle phase capillary glass tube 2 in the outer phase capillary glass tube 3, the nesting depth is 100 μm, then nest the tapered outlet of the inner phase capillary glass tube 1 in the middle phase capillary glass tube 2, the nesting depth is 100 μm, and make the three capillary glass tubes centered and located on the same straight line;

[0035] S2: use a syringe 5 to suck in 20 mL of mineral oil, 20 mL of an acrylate ester mixture and 20 mL of a polyvinyl alcohol solution with a concentration of 10 wt% (solvent is methanol), then fix the syringe 5 on the injection pump 6, inject the mineral oil into the inner phase capillary glass tube 1 at a flow rate of 20 μL / min through the injection pump 6, at the same time inject the acrylate ester mixture into the middle phase capillary glass tube 2 at a flow rate of 50 μL / min through the injection pump 6, at the same time inject the polyvinyl alcohol solution into the outer phase capillary glass tube 3 at a flow rate of 400 μL / min through the injection pump 6, the acrylate ester mixture surrounds the mineral oil as the middle phase, the polyvinyl alcohol solution surrounds the middle phase as the outer phase, form an emulsion droplet at the bottom end of the outer phase capillary glass tube 3, collect the emulsion droplet with a polyvinyl alcohol aqueous solution with a concentration of 5 wt%;

[0036] S3: after the emulsion droplet is formed for 30 s, irradiate the emulsion droplet in the aqueous solution with a UV lamp with a power of 400 W, the emulsion droplet undergoes a polymerization reaction under UV light irradiation, after 5 min of reaction, stable microcapsules are formed, then wash the microcapsules with deionized water for 6 times, then put the microcapsules into a vacuum drying oven, dry at 120℃ for 10 h, and obtain the product.

[0037] Example 2

[0038] A method for preparing a bio-based microcapsule, the method comprising the following steps:

[0039] ①Preparation of an acrylate ester mixture

[0040] According to parts by weight, 1 part of AESO is added to 3 parts of an IBOA solution with a concentration of 75 wt% (solvent is ethanol), after mixing uniformly, an AESO-IBOA mixed solution is obtained, then 1 part of a methyl propionyl phenone solution with a concentration of 0.5 wt% (solvent is ethanol) is added to the AESO-IBOA mixed solution, and the acrylate ester mixture is obtained.

[0041] ②Preparation of bio-based microcapsules

[0042] S1: Select two original capillary round glass tubes that have not been drawn, one end of one of them is polished to a taper with 2500 grit sandpaper, the diameter of the tapered outlet is 100 μm and the tapered outlet tip is flat without gaps, this capillary round glass tube is used as the inner phase capillary glass tube 1; the other end is polished to a taper with 2000 grit sandpaper, the diameter of the tapered outlet is 200 μm and the tapered outlet tip is flat without gaps, this capillary round glass tube is used as the middle phase capillary glass tube 2; select another original capillary round glass tube that has not been drawn with an outer diameter of 500 μm and an inner diameter of 400 μm as the outer phase capillary glass tube 3; under a microscope, nest the tapered outlet of the middle phase capillary glass tube 2 in the outer phase capillary glass tube 3, the nesting depth is 100 μm, then nest the tapered outlet of the inner phase capillary glass tube 1 in the middle phase capillary glass tube 2, the nesting depth is 100 μm, and make the three capillary glass tubes centered on the same straight line;

[0043] S2: Use a syringe 5 to suck in 20 mL of mineral oil, 20 mL of an acrylic ester mixture and 20 mL of a polyvinyl alcohol solution with a concentration of 5 wt% (solvent is methanol), then fix the syringe 5 on the injection pump 6, inject the mineral oil into the inner phase capillary glass tube 1 at a flow rate of 15 μL / min through the injection pump 6, at the same time inject the acrylic ester mixture into the middle phase capillary glass tube 2 at a flow rate of 45 μL / min through the injection pump 6, and at the same time inject the polyvinyl alcohol solution into the outer phase capillary glass tube 3 at a flow rate of 350 μL / min through the injection pump 6, the acrylic ester mixture surrounds the mineral oil as the middle phase, and the polyvinyl alcohol solution surrounds the middle phase as the outer phase, forming an emulsion droplet at the bottom end of the outer phase capillary glass tube 3, and collecting the emulsion droplet with a polyvinyl alcohol aqueous solution with a concentration of 5 wt%;

[0044] S3: After the emulsion droplet is formed for 30 s, irradiate the emulsion droplet in the aqueous solution with a UV lamp with a power of 400 W, the emulsion droplet undergoes a polymerization reaction under UV irradiation, after 6 min of reaction, stable microcapsules are formed, then wash the microcapsules with deionized water for 5 times, then put the microcapsules into a vacuum drying oven, dry at 100℃ for 12 h, and obtain the bio-based microcapsules.

[0045] Example 3

[0046] A method for preparing bio-based microcapsules, the method comprising the following steps:

[0047] ①Preparation of an acrylic ester mixture

[0048] According to parts by weight, 1 part of AESO is added to 3 parts of IBOA solution with a concentration of 75 wt% (solvent is ethyl acetate), and after uniform mixing, an AESO-IBOA mixed solution is obtained, then 1 part of methyl propionyl phenone solution with a concentration of 0.5 wt% (solvent is ethyl acetate) is added to the AESO-IBOA mixed solution, and the product is obtained.

[0049] 2. Preparation of bio-based microcapsules

[0050] S1: Select two original capillary round glass tubes that have not been drawn, one end of one of them is polished to a taper with 2500 grit sandpaper, the diameter of the tapered outlet is 200 μm and the tapered outlet tip is flat without gaps, this capillary round glass tube is used as the inner phase capillary glass tube 1; the other end is polished to a taper with 2000 grit sandpaper, the diameter of the tapered outlet is 300 μm and the tapered outlet tip is flat without gaps, this capillary round glass tube is used as the middle phase capillary glass tube 2; select another original capillary round glass tube with an outer diameter of 500 μm and an inner diameter of 400 μm that has not been drawn, and nest the tapered outlet of the middle phase capillary glass tube 2 in the outer phase capillary glass tube 3 under a microscope, the nesting depth is 100 μm, then nest the tapered outlet of the inner phase capillary glass tube 1 in the middle phase capillary glass tube 2, the nesting depth is 100 μm, and make the three capillary glass tubes centered on the same straight line;

[0051] S2: Use a syringe 5 to suck in 20 mL of mineral oil, 20 mL of acrylate mixture and 20 mL of polyvinyl alcohol solution with a concentration of 15 wt% (solvent is methanol), then fix the syringe 5 on the injection pump 6, inject the mineral oil into the inner phase capillary glass tube 1 at a flow rate of 35 μL / min through the injection pump 6, at the same time inject the acrylate mixture into the middle phase capillary glass tube 2 at a flow rate of 55 μL / min through the injection pump 6, and at the same time inject the polyvinyl alcohol solution into the outer phase capillary glass tube 3 at a flow rate of 550 μL / min through the injection pump 6, the acrylate mixture surrounds the mineral oil as the middle phase, and the polyvinyl alcohol solution surrounds the middle phase as the outer phase, forming an emulsion droplet at the bottom end of the outer phase capillary glass tube 3, and collecting the emulsion droplet with a polyvinyl alcohol aqueous solution with a concentration of 5 wt%;

[0052] S3: After the emulsion droplet is formed for 30 s, irradiate the emulsion droplet in the aqueous solution with a UV lamp with a power of 400 W, the emulsion droplet undergoes a polymerization reaction under UV irradiation, and after 5 min of reaction, stable microcapsules are formed, then wash the microcapsules with deionized water for 7 times, and then place the microcapsules in a vacuum drying oven and dry at 150℃ for 12 h, and the product is obtained.

[0053] Comparative Example 1

[0054] A method for preparing microcapsules, which is different from the method of Example 1 in that the components of the acrylic ester mixture in step 1 are different, and the IBOA solution is omitted.

[0055] Comparative Example 2

[0056] A method for preparing microcapsules, which is different from the method of Example 1 in that the components of the acrylic ester mixture in step 1 are different, and the AESO is omitted.

[0057] Comparative Example 3

[0058] A method for preparing microcapsules, which is different from the method of Example 1 in that the components of the acrylic ester mixture in step 1 are different, and the proportion of the IBOA solution (solvent is ethanol) in the acrylic ester mixture in this comparative example is 1 part, accounting for 75wt%.

[0059] Comparative Example 4

[0060] A method for preparing microcapsules, which is different from the method of Example 1 in that the components of the acrylic ester mixture in step 1 are different, and 1 part of AESO and 3 parts of IBOA solution with a concentration of 75wt% are replaced by 4 parts of polyurea.

[0061] Comparative Example 5

[0062] A method for preparing microcapsules, which is different from the method of Example 1 in that the flow rate of mineral oil in step S2 is adjusted to 45μL / min, the flow rate of the acrylic ester mixture is adjusted to 70μL / min, and the flow rate of the polyvinyl alcohol solution is adjusted to 650μL / min.

[0063] Experimental Example

[0064] ① Structure test

[0065] The image of the bio-based microcapsules prepared in Example 1 under an optical microscope is shown in FIG. 1. Figure 2 As can be seen from the figure, the microcapsule surface morphology is smooth, and is a core-shell structure, and has good sphericity, high monodispersity.

[0066] ② The microcapsules prepared in Examples 1-3 and Comparative Examples 1-5 were added to the preparation of concrete specimens to self-repair concrete cracks of the same degree. The overall performance after crack repair was tested. The repair steps were as follows: a constant pressure of 70% of the maximum stress value was applied to the specimen for 180 seconds, then unloaded. The damaged specimen was left for 2 days to allow the microcapsules to repair the cracks. The test values ​​after repair are shown in Table 1. As can be seen from the table, the microcapsules prepared in the examples showed higher strength repair rate and strength recovery rate in repairing concrete cracks, and the compressive strength of the repaired concrete was also higher. IBOA solution was omitted in Comparative Example 1. IBOA can improve the strength and toughness of microcapsules. In addition, AESO cannot work synergistically with IBOA, resulting in a further reduction in the toughness of this microcapsule compared with the sample in the examples. The integrity of the microcapsules was also reduced during concrete mixing, thus showing poor performance in repairing concrete cracks. AESO has lubricating and penetrating properties. The omission of AESO in Comparative Example 2 is not conducive to the penetration of microcapsules into cracks. The tiny pores in the microcapsules hinder crack repair, preventing IBOA from working synergistically with AESO. This reduces the toughness and strength of the capsule walls, resulting in a weakened repair effect. In Comparative Example 3, the IBOA solution in the acrylate mixture was only 1 part, leading to insufficient strength and toughness of the microcapsules and poor performance in repairing concrete cracks. In Comparative Example 4, replacing IBOA and AESO with polyurea significantly reduced the repair performance of the microcapsules. In Comparative Example 5, adjusting the flow rate resulted in non-uniform microcapsule properties, leading to poor repair performance in concrete crack repair.

[0067] Table 1

[0068]

[0069] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A biobased microcapsule, characterized in that, The bio-based microcapsule is composed of a capsule core and a capsule wall, the capsule core is mineral oil; the capsule wall raw material is an acrylate mixture; the acrylate mixture is prepared by the following method: adding a soybean oil epoxidized acrylate into an isobornyl acrylate solution to obtain a soybean oil epoxidized acrylate-isobornyl acrylate mixed solution, then adding a photoinitiator into the soybean oil epoxidized acrylate-isobornyl acrylate mixed solution, and the photoinitiator is obtained; the solvent of the isobornyl acrylate solution is ethyl acetate, diethyl ether or ethanol, and the concentration of the isobornyl acrylate solution is 75 wt%; the photoinitiator is a methylpropanoyl phenone solution with a concentration of 5 wt%, and the solvent of the methylpropanoyl phenone solution is ethyl acetate, diethyl ether or ethanol; the acrylate mixture includes 1 part of soybean oil epoxidized acrylate, 3 parts of isobornyl acrylate solution and 1 part of photoinitiator by weight.

2. The method of producing a bio-based microcapsule according to claim 1, characterized in that, It comprises the following steps: S1: nest the tapered outlet of the middle-phase capillary glass tube (2) in the outer-phase capillary glass tube (3) with a nesting depth of 100 μm; then nest the tapered outlet of the inner-phase capillary glass tube (1) in the middle-phase capillary glass tube (2) with a nesting depth of 100 μm, and set up a material injection system at the inlet of the inner-phase capillary glass tube (1), the middle-phase capillary glass tube (2) and the outer-phase capillary glass tube (3) respectively, to complete the construction of the microfluidic device; S2: inject mineral oil into the inner-phase capillary glass tube (1) at a flow rate of 15-35 μL / min, inject an acrylate mixture into the middle-phase capillary glass tube (2) at a flow rate of 45-55 μL / min, and inject a polyvinyl alcohol solution with a concentration of 5-15 wt% into the outer-phase capillary glass tube (3) at a flow rate of 350-550 μL / min, to collect the emulsion droplets formed at the bottom end of the outer-phase capillary glass tube (3) with the polyvinyl alcohol aqueous solution; S3: after polymerization, washing and drying of the emulsion droplets, the bio-based microcapsule is obtained; the polymerization condition is to irradiate the emulsion droplets with ultraviolet light, the power of the ultraviolet lamp is 400 W, and the irradiation time is 5-6 min; the drying temperature is 100-150 ℃, and the drying time is 8-12 h.

3. The method of producing biobased microcapsules according to claim 2, characterized in that: The diameter of the tapered outlet of the inner-phase capillary glass tube (1) in step S1 is 100-200 μm; the diameter of the tapered outlet of the middle-phase capillary glass tube (2) is 200-300 μm; and the outer diameter of the outer-phase capillary glass tube (3) is 500 μm, and the inner diameter is 400 μm.

4. The method of producing biobased microcapsules according to claim 2, characterized in that: The solvent of the polyvinyl alcohol solution in step S2 is methanol.

5. The method of preparing biobased microcapsules according to claim 2, characterized in that: The concentration of the polyvinyl alcohol aqueous solution in step S2 is 5 wt%.

6. The method of preparing a bio-based microcapsule according to claim 2, characterized in that: The washing method in step S3 is to wash with deionized water for 5-7 times.

7. Use of a bio-based microcapsule, characterized in that: The bio-based microcapsule of claim 1 is used for preparing self-repairing concrete.

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