CO2 load-response type self-repairing microcapsule as well as preparation method and application thereof

Abstract

The invention discloses a CO2 load-response type self-repairing microcapsule as well as a preparation method and application thereof. The self-repairing microcapsule takes a modified repairing component as a core material and MOFs (at) SiO2 as a wall material; wherein the repairing component is a substance capable of converting CO2 into stable inorganic carbonate, and the repairing component, polyacrylamide and chitosan form hydrogel under the action of a cross-linking agent so as to be modified; according to the MOFs (at) SiO2, the surface of a SiO2 shell is modified with an MOFs metal organic framework material. The CO2 load-response type self-repairing microcapsule disclosed by the invention has relatively high selective adsorption performance on CO2, can have relatively good stability in concrete, can efficiently repair microcracks in the concrete, and can guarantee long-term integrity of the concrete and safe and permanent storage of CO2.

Description

Technical Field

[0001] This invention relates to a self-healing microcapsule, specifically to a CO2-loaded-responsive self-healing microcapsule, its preparation method, and its application. Background Technology

[0002] Tunnel engineering is an indispensable key infrastructure in modern railway transportation systems. Due to the complexity of ultra-deep buried environments, these tunnels inevitably face multiple challenges such as high ground stress, complex chemical corrosion environments, and temperature gradient changes.

[0003] Concrete, as a key structural material for tunnels, plays a decisive role in their safety and durability. However, in ultra-deep burial environments, concrete is prone to deterioration due to crack initiation and chemical erosion, adversely affecting the long-term operation and safe service of tunnels. Tunnel concrete typically possesses high strength and low permeability, but under the combined effects of high ground stress and erosion, its relatively poor tensile strength makes it highly susceptible to cracking. In the presence of cracks, the high concentration of CO2 in ultra-deep burial spaces further exacerbates the carbonation problem of concrete, leading to a significant decline in its mechanical properties and durability.

[0004] Currently, concrete crack repair mainly includes methods such as grouting, surface coating, and crack injection. Although these methods are effective in crack repair, bottlenecks remain in terms of real-time repair, effectiveness against deep cracks, and cost control.

[0005] Microencapsulation self-healing technology overcomes the spatiotemporal limitations of traditional repair methods through an encapsulation-release mechanism. The capsule core can repair cracks by reacting with environmental substances, interacting with matrix components, or through synergistic effects of multiple components. However, microencapsulation self-healing technology still faces many challenges, such as the adaptability of the concrete self-healing process to the service environment, the controllability of the repair process, and the matching of crack closure rate with mechanical property recovery rate. Therefore, it is necessary to improve the long-term adaptability of microcapsules in concrete and their efficient capture of CO2 gas in CO2-rich environments.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a CO2-loaded, responsive, self-healing microcapsule, its preparation method, and its application. The microcapsule of this invention has high selective adsorption performance for CO2, good stability in concrete, and can efficiently repair microcracks inside concrete, thus ensuring the long-term integrity of concrete and the safe and permanent sequestration of CO2.

[0008] To achieve the above objectives, the present invention provides a CO2-loaded, responsive, self-healing microcapsule. This self-healing microcapsule uses a modified repair component as the core material and MOFs@SiO2 as the wall material. The repair component is a substance capable of converting CO2 into stable inorganic carbonates. This repair component is modified by forming a hydrogel with polyacrylamide and chitosan under the action of a crosslinking agent. The MOFs@SiO2 is a metal-organic framework material (MOFs) modified onto the surface of a SiO2 shell.

[0009] Preferably, the repair component is selected from any one or more of tricalcium silicate, β-dicalcium silicate, γ-dicalcium silicate, and calcium silicate; or / and, the MOFs@SiO2 is obtained by reacting SiO2-coated core material microcapsules with zirconium salt, 2-aminoterephthalic acid, organic linker, and regulator; or / and, the crosslinking agent is selected from N,N-methylenebisacrylamide.

[0010] A second objective of this invention is to provide a method for preparing the aforementioned CO2-loaded, responsive, self-healing microcapsules, the method comprising the following steps: (1) Mix the modified repair component, the precursor tetraethyl orthosilicate and sodium dodecylbenzenesulfonate evenly to form a uniform sol, adjust the pH value to 9~10, stir to form gel-coated microcapsules, and dry the obtained microcapsules to obtain SiO2-coated core material microcapsules. (2) Dissolve the metal ion salt and organic ligand in organic solvent A to obtain solution A; dissolve the organic linker and regulator in organic solvent B to obtain solution B; organic solvent A and organic solvent B are miscible. Mix solution A and solution B, and sonicate. Suspend the SiO2-coated core material microcapsules in the mixed solution of solution A and B, and react at 110~130℃ (the solid particles obtained from the reaction can be suspended again in the mixed solution of solution A and B, and reacted at 110~130℃. This process can be repeated several times) to obtain CO2-loaded-responsive concrete self-healing microcapsules.

[0011] Preferably, in step (1), the mass ratio of the repair component, the precursor tetraethyl orthosilicate, and sodium dodecylbenzenesulfonate is 100:20:15; or / and, in step (1), the repair component is selected from dicalcium γ-silicate, which is modified by forming a hydrogel with polyacrylamide and chitosan under the action of a crosslinking agent; or / and, in step (1), the pH value is adjusted by ammonia; or / and, in step (1), the drying temperature is 60°C; or / and, in step (1), ultrasonic dispersion is used to form a uniform sol; or / and, in step (1), the stirring is performed at a speed of 300~1000 rpm. Stirring; or / and, in step (2), the organic solvent A is selected from ethanol, and the organic solvent B is selected from N,N-dimethylformamide; or / and, in step (2), the metal ion salt is selected from zirconium salt, the organic ligand is selected from 2-aminoterephthalic acid, the organic linker is selected from biphenyl-4,4'-dicarboxylic acid, and the regulator is selected from benzoic acid. By using biphenyl-4,4'-dicarboxylic acid and benzoic acid as organic linker and regulator, respectively, the surface of SiO2 can be modified so that SiO2 can form a chemical cross-linked structure with MOFS; or / and, in step (2), after the reaction is completed, the mixture is washed with ethanol and then dried at 70°C.

[0012] More preferably, in step (1), the mass ratio of γ-dicalcium silicate, polyacrylamide and chitosan is 1:0.5:0.5; or / and, the crosslinking agent is selected from N,N-methylenebisacrylamide.

[0013] More preferably, in step (2), the volume ratio of organic solvent A to organic solvent B is 1:1; or / and, in step (2), the molar ratio of zirconium salt, 2-aminoterephthalic acid, biphenyl-4,4'-dicarboxylic acid and benzoic acid is 1.7:1.7:0.1:2; or / and, in step (2), the amount of zirconium salt, 2-aminoterephthalic acid and organic solvent A is 1.7 mmol:1.7 mmol:20 mL; or / and, in step (2), the amount of biphenyl-4,4'-dicarboxylic acid, benzoic acid and organic solvent B is 0.1 mmol:2 mmol:20 mL; or / and, in step (2), the zirconium salt is selected from ZrCl4 or ZrOCl2; or / and, in step (2), the mass ratio of the microcapsule of the SiO2-coated core material to the volume ratio of the mixed solution of solutions A and B is 1 g:20 mL.

[0014] More preferably, the SiO2-coated core material microcapsules are repeatedly reacted with the mixed solution of solutions A and B several times.

[0015] Preferably, the repair component is selected from dicalcium γ-silicate, and the preparation method of the repair component includes: adding polyacrylamide and chitosan to water respectively, heating and stirring thoroughly, gradually adding the polyacrylamide solution dropwise to the chitosan solution to obtain a mixed solution, adding dicalcium γ-silicate to the mixed solution under ultrasonic assistance and adding a crosslinking agent to react, and obtaining a hydrogel-modified γ-C2S core.

[0016] More preferably, the mass ratio of polyacrylamide to chitosan is 1:1; or / and, the heating temperature is 50°C; or / and, the crosslinking agent is selected from N,N-methylenebisacrylamide.

[0017] A third objective of this invention is to provide the application of the aforementioned CO2 load-responsive self-healing microcapsules in concrete repair.

[0018] A fourth objective of this invention is to provide a self-healing concrete containing the aforementioned CO2 load-responsive self-healing microcapsules.

[0019] Preferably, the mass fraction of CO2 load-responsive self-healing microcapsules in the self-healing concrete is 2.5~3.8%.

[0020] Preferably, the self-healing concrete comprises: cement, sand, stone, water-reducing agent, CO2 load-responsive self-healing microcapsules, and water.

[0021] More preferably, the mass ratio of the cement, sand, stone, water-reducing agent, CO2 load-responsive self-healing microcapsules and water is 440:650~680:1167:5~8:66~96:184~185.

[0022] More preferably, the water-reducing agent includes naphthalene-based water-reducing agents or polycarboxylate-based water-reducing agents.

[0023] More preferably, the sand has a particle size of 0.2~0.5mm; and the stone has a specific surface area of ​​10~15mm.

[0024] The CO2-loaded-responsive self-healing microcapsules, their preparation method, and applications of the present invention have the following advantages: This invention utilizes CO2-loaded, responsive, self-healing microcapsules, which, when filled into concrete, can effectively adsorb high concentrations of CO2 gas in ultra-deep buried tunnels. Simultaneously, the CO2-loaded, responsive, self-healing microcapsules can release γ-C2S powder, which reacts with the captured CO2 gas to generate CaCO3, filling the cracks. This dense CaCO3 layer can effectively repair microcracks in the concrete, increasing the safe service life of concrete in ultra-deep buried tunnels.

[0025] During the service life of concrete, the CO2-loaded, responsive self-healing microcapsules of this invention can utilize the efficient adsorption of CO2 from the air by MOFs to achieve directional CO2 storage. When cracks occur, the MOFs, acting as the capsule wall, have a targeting effect and can release CO2 under the action of tip stress to induce rapid carbon mineralization reaction of γ-C2S, thereby achieving self-healing of cracks. The concrete self-healing microcapsules with γ-C2S as the core and MOFs@SiO2 as the capsule wall can ensure the restoration of mechanical properties after matrix repair. Through the organic hybrid modification of the hydrogel, the hydrogel can regulate the reaction environment of the crack through its flexible structure, providing moisture and suitable diffusion paths for the carbonization reaction. In addition, the swelling properties of the hydrogel can compensate for the volume shrinkage of γ-C2S carbonization products during long-term service, improving the long-term effectiveness of crack repair.

[0026] Therefore, the CO2-loaded-responsive self-healing microcapsules prepared in this invention have high selective adsorption performance for CO2, good stability in concrete, and can efficiently repair microcracks inside concrete, thus ensuring the long-term integrity of concrete and the safe and permanent sequestration of CO2. Attached Figure Description

[0027] Figure 1 Infrared spectrum of CO2-loaded-responsive self-healing microcapsules prepared according to the present invention.

[0028] Figure 2 Scanning electron microscope image of the CO2-loaded-responsive self-healing microcapsules prepared in this invention.

[0029] Figure 3 This is a schematic diagram of the CO2-loaded, responsive, self-healing microcapsule structure prepared according to the present invention.

[0030] Figure 4 This is a mechanical property diagram of CO2-load-responsive self-healing concrete microcapsules incorporated under carbonation curing conditions according to Embodiment 2 of the present invention.

[0031] Figure 5 This is a microscopic morphology image of γ-C2S powder in the CO2-loaded-responsive self-healing microcapsules prepared in this invention, after reacting with CO2 to repair microcracks. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] It should be noted that: Unless otherwise specified in the examples, standard conditions or conditions recommended by the manufacturer should be followed. Instruments whose manufacturers are not specified are all commercially available products. Raw materials and reagents whose manufacturers are not specified are all commercially available goods or can be prepared using known methods.

[0034] In this invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are used only for simplicity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0035] The features mentioned in this invention can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification, provided that there is no contradiction in the combination of these features. Each feature disclosed in the specification can be replaced by any alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are merely general examples of equivalent or similar features.

[0036] Example 1 A CO2-loaded, responsive, self-healing microcapsule is prepared by the following steps: (1) 0.5 g of polyacrylamide (PAM) and 0.5 g of chitosan (CS) were added to 100 mL of deionized water, respectively. After stirring thoroughly at 50 °C, the PAM solution was gradually added dropwise to the CS solution. Then, under ultrasonic assistance, 1 g of γ-C2S was added to the above mixed solution and 100 mL of N,N-methylenebisacrylamide crosslinking agent was added. The mixture was reacted for several hours to obtain hydrogel-modified γ-C2S capsule core.

[0037] (2) The hydrogel-modified γ-C2S capsule core prepared in step (1) was mixed with TEOS (tetraethyl orthosilicate) and SDS (sodium dodecylbenzenesulfonate) in water at a mass ratio of 100:20:15. After ultrasonic dispersion for 30 min, a uniform sol was formed. Ammonia was titrated to keep the pH of the solution between 9 and 10. Hydrolysis and condensation were promoted under stirring at 300 rpm at room temperature to form gel-coated microcapsules. The obtained microcapsules were centrifuged, washed with ethanol, and dried at 60°C for 12 h to obtain SiO2-coated γ-C2S microcapsules. (3) Dissolve 42.5 mmol ZrCl4 and 42.5 mmol 2-aminoterephthalic acid in 500 mL of ethanol solution to obtain solution A; dissolve 2.5 mmol biphenyl-4,4'-dicarboxylic acid and 50 mmol benzoic acid in 500 mL of N,N-dimethylformamide (DMF) to obtain solution B; mix solution A and solution B and sonicate, then suspend 0.5 g SiO2-coated γ-C2S microcapsules in 10 mL of the mixture of solution A and B, react at 120 °C for 30 min, then filter, and repeat the process on the obtained particles 10 times so that the MOFs structure can be well coated on the outside of the microcapsules; wash the modified particles several times with ethanol solution, and dry them at 70 °C for 12 h to obtain CO2-loaded-responsive self-healing microcapsules.

[0038] The concrete prepared from the CO2-loaded-responsive self-healing microcapsules of Example 1 is prepared by a method comprising: 66g of CO2-loaded responsive self-healing microcapsules were added to 440g of cement, 680g of sand (particle size 0.3mm), and 1167g of stone (specific surface area 11m²). 2 Mix 5.72g of naphthalene-based water-reducing agent and 184.8g of water to prepare concrete.

[0039] The prepared concrete was placed on an electronic scale and weighed to obtain m1. The concrete was then placed in a CO2-sealed device and allowed to adsorb CO2 for 7 days. Afterward, the concrete was removed and weighed again to obtain m2. The adsorption capacity of the CO2-loaded, responsive concrete self-healing microcapsules was calculated.

[0040] Example 2 A type of concrete prepared from CO2-loaded, responsive, self-healing microcapsules is prepared using a method that is basically the same as that in Example 1, except that: The amount of CO2-loaded-responsive self-healing microcapsules added in Example 1 was different, while in Example 2, 96g of CO2-loaded-responsive self-healing microcapsules were added.

[0041] Example 3 A CO2-loaded, responsive, self-healing microcapsule is prepared using a method essentially the same as that in Example 1, with the difference being: In step (3), the reaction process of SiO2-coated γ-C2S microcapsules with the mixed solution of solutions A and B is repeated 5 times.

[0042] The concrete prepared from the CO2-loaded-responsive self-healing microcapsules of Example 3 was prepared using the same method as that of Example 1.

[0043] Compare with Example 1 The SiO2-coated γ-C2S microcapsules prepared in Example 1 were used as Control Example 1, without the MOF structure coating modification process in Example 1.

[0044] The concrete prepared from the CO2-loaded-responsive self-healing microcapsules of Comparative Example 1 was prepared using the same method as in Example 1.

[0045] Compare with Example 2 A type of concrete, the preparation method of which includes: Mix 440g cement, 680g sand (particle size 0.3mm), and 1167g stone (specific surface area 11m²). 2 Mix 5.72g of naphthalene-based water-reducing agent and 184.8g of water to prepare concrete.

[0046] Experimental Example 1: Characterization of CO2 Load-Responsive Concrete Self-Healing Microcapsules like Figure 1 The image shows the infrared spectrum of the CO2-loaded-responsive self-healing concrete microcapsules prepared in Example 1 of this invention. As can be seen from the image, at 3240 cm⁻¹... -1 The peak at 1619 cm⁻¹ is a moderate intensity vibration peak of the OH bond. -1 and 1402cm -1 The peak at 586 cm⁻¹ is the vibrational peak of COO⁻, and also characterizes C=O and CH bonds. -1 The vibrational peaks are symmetrical vibrational peaks of O-Zr-O. These peaks indicate the presence of typical functional groups in the synthesized MOF structures.

[0047] like Figure 2 The image shown is a scanning electron microscope image of CO2-loaded-responsive self-healing concrete microcapsules prepared in Example 1 of the present invention. It can be seen from the image that the synthesized self-healing cement is a typical sphere, and it can also be seen that the deposition of MOF crystals makes the cement surface relatively rough.

[0048] Experimental Example 2: Determination of Adsorption Capacity The concrete prepared in each embodiment or comparative example was placed on an electronic scale and weighed to be m1. Then, the concrete was placed in a CO2 sealed device and allowed to adsorb CO2 for a period of time (7 days for Examples 1-3, 12 hours for Comparative Example 1). After that, the concrete was removed and weighed again to be m2. The adsorption capacity of the concrete was calculated.

[0049] In this case, following the above method, CO2 was replaced with N2 adsorption for 7 days, and the adsorption capacity of N2 adsorbed by the CO2-loaded-responsive concrete self-healing microcapsules in Example 1 was measured.

[0050] The concrete masses m1 and m2 and adsorption capacities obtained in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0051] Table 1. Adsorption capacity of CO2-loaded, responsive, self-healing microcapsules

[0052] According to the experimental results in Table 1, the CO2-loaded-responsive self-healing microcapsules of this invention can exist stably in concrete and can efficiently and selectively adsorb CO2 gas, but have poor N2 adsorption effect. With increasing carbonation time, the CO2-loaded-responsive self-healing microcapsules can selectively adsorb more CO2 gas. This is because: Figure 3 As shown, self-healing microcapsules with γ-C2S as the core and MOFs@SiO2 as the capsule wall can ensure the restoration of mechanical properties after matrix repair. Through organic hybrid modification of the hydrogel, the hydrogel can regulate the reaction environment of the crack through its flexible structure, providing moisture and suitable diffusion pathways for the carbonization reaction. Furthermore, the swelling properties of the hydrogel can compensate for the volume shrinkage of γ-C2S carbonization products during long-term service, improving the long-term effectiveness of crack repair. During the service life of concrete, the high adsorption capacity of MOFs for CO2 in the air enables the directional storage of CO2. When cracks occur, MOFs, acting as the capsule wall, have a targeting effect, releasing CO2 under the action of tip stress to induce rapid carbon mineralization of γ-C2S, thereby achieving self-healing of the crack.

[0053] Experiment Example 2 Repair Performance Test The concrete obtained in Comparative Example 2 was placed in a CO2 environment for continuous curing for a period of time, then removed and placed in a compressive strength testing machine to measure its compressive strength (i.e., the compressive strength before thermal stress failure), which was recorded as . .

[0054] The CO2-loaded, saturated self-healing microcapsules were incorporated into concrete according to the method described in Example 1. After natural curing for 7 days, the concrete was removed and subjected to thermal stress at 100°C. Subsequently, the concrete was placed in a natural environment to allow for self-healing for a certain period of time. Finally, its compressive strength (i.e., the compressive strength of the concrete prepared with the CO2-loaded, responsive self-healing microcapsules after repair) was measured in a compressive strength testing machine and recorded as follows: The formula for calculating the strength repair rate ξ of concrete prepared from CO2-load-responsive self-healing microcapsules is shown below: ; The results are as follows Figure 4As shown in Table 2. The experimental results show that the compressive strength of the CO2-loaded-responsive self-healing microcapsules was significantly improved compared to the control group. The increase in compressive strength was more pronounced in the early stages, but the effect diminished with increasing carbonization time. The strength recovered to 35 MPa at 28 days. This is because the γ-C2S powder released from the CO2-loaded-responsive self-healing microcapsules reacts with the captured CO2 gas to generate CaCO3, which fills the cracks (e.g., ...). Figure 5 (As shown). This dense CaCO3 layer can effectively repair microcracks in concrete, increasing the safe service life of concrete in ultra-deep buried tunnels.

[0055] Table 2. Strength restoration rate after carbonization in the group incorporating self-healing microcapsules and the blank group.

[0056] This embodiment utilizes CO2-loaded, responsive, self-healing microcapsules to fill concrete. From an effectiveness standpoint, these microcapsules can stably exist within the concrete and efficiently and selectively adsorb CO2 gas. From an environmental perspective, filling concrete with these microcapsules can effectively adsorb the high concentrations of CO2 gas found in ultra-deep buried tunnels. From an engineering perspective, the CO2-loaded, responsive, self-healing microcapsules release γ-C2S, which reacts with the captured CO2 to form a dense CaCO3 layer, thereby repairing microcracks within the concrete and improving its long-term safe service life.

[0057] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A CO2-loaded, responsive, self-healing microcapsule, characterized in that, The self-healing microcapsule uses modified repair components as the core material and MOFs@SiO2 as the wall material; The repair component is a substance that can convert CO2 into stable inorganic carbonates. The repair component is modified by forming a hydrogel with polyacrylamide and chitosan under the action of a crosslinking agent. The MOFs@SiO2 is a metal-organic framework material with MOFs modified on the surface of a SiO2 shell.

2. The CO2-loaded, responsive, self-healing microcapsule according to claim 1, characterized in that, The repair component is selected from any one or more of tricalcium silicate, β-dicalcium silicate, γ-dicalcium silicate and calcium silicate; Or / and, the MOFs@SiO2 are obtained by reacting SiO2-coated core material microcapsules with zirconium salt, 2-aminoterephthalic acid, organic linker and modifier; Or / and, the crosslinking agent is selected from N,N-methylenebisacrylamide.

3. The method for preparing CO2-loaded-responsive self-healing microcapsules as described in claim 1 or 2, characterized in that, The method includes the following steps: (1) Mix the modified repair component, the precursor tetraethyl orthosilicate and sodium dodecylbenzenesulfonate evenly to form a uniform sol, adjust the pH value to 9~10, stir to form gel-coated microcapsules, and dry the obtained microcapsules to obtain SiO2-coated core material microcapsules. (2) Dissolve the metal ion salt and organic ligand in organic solvent A to obtain solution A; dissolve the organic linker and regulator in organic solvent B to obtain solution B; organic solvent A and organic solvent B are miscible. Mix solution A and solution B, and sonicate. Suspend the SiO2-coated core material microcapsules in the mixed solution of solution A and B, and react at 110~130℃ to obtain CO2-loaded-responsive concrete self-healing microcapsules.

4. The preparation method according to claim 3, characterized in that, In step (1), the mass ratio of the repair component, the precursor tetraethyl orthosilicate, and sodium dodecylbenzenesulfonate is 100:20:15; Or / and, in step (1), the repair component is selected from dicalcium γ-silicate, which is modified by forming a hydrogel with polyacrylamide and chitosan under the action of a crosslinking agent; Or / and, in step (1), the pH value is adjusted using ammonia; Or / and, in step (1), the drying temperature is 60°C; Or / and, in step (1), ultrasonic dispersion is used to form a uniform sol; Or / and, in step (1), the stirring is performed at a speed of 300~1000 rpm; Or / and, in step (2), the organic solvent A is selected from ethanol, and the organic solvent B is selected from N,N-dimethylformamide; Or / and, in step (2), the metal ion salt is selected from zirconium salt, the organic ligand is selected from 2-aminoterephthalic acid, the organic linker is selected from biphenyl-4,4'-dicarboxylic acid, and the modifier is selected from benzoic acid; Or / and, in step (2), after the reaction is complete, the mixture is washed with ethanol and then dried at 70°C.

5. The preparation method according to claim 4, characterized in that, In step (1), the mass ratio of dicalcium silicate, polyacrylamide and chitosan is 1:0.5:0.5; Or / and, the crosslinking agent is selected from N,N-methylenebisacrylamide.

6. The preparation method according to claim 4, characterized in that, In step (2), the volume ratio of organic solvent A to organic solvent B is 1:1; Or / and, in step (2), the molar ratio of the zirconium salt, 2-aminoterephthalic acid, biphenyl-4,4'-dicarboxylic acid and benzoic acid is 1.7:1.7:0.1:2; Or / and, in step (2), the ratio of the zirconium salt, 2-aminoterephthalic acid and organic solvent A is 1.7 mmol: 1.7 mmol: 20 mL; Or / and, in step (2), the amount of biphenyl-4,4'-dicarboxylic acid, benzoic acid and organic solvent B is 0.1 mmol: 2 mmol: 20 mL; Or / and, in step (2), the zirconium salt is selected from ZrCl4 or ZrOCl2; Or / and, in step (2), the mass ratio of the microcapsules of the SiO2-coated core material to the volume ratio of the mixed solution of solutions A and B is 1 g: 20 mL.

7. The preparation method according to any one of claims 4 to 6, characterized in that, The repair component is selected from dicalcium γ-silicate, and the preparation method of the repair component includes: Polyacrylamide and chitosan were added to water separately, heated and stirred thoroughly, and then the polyacrylamide solution was gradually added dropwise to the chitosan solution to obtain a mixed solution. Under ultrasonic assistance, dicalcium γ-silicate was added to the mixed solution and a crosslinking agent was added to react, resulting in a hydrogel-modified γ-C2S capsule core.

8. The preparation method according to claim 7, characterized in that, The mass ratio of polyacrylamide to chitosan is 1:1; Or / and, the heating is at a temperature of 50°C; Or / and, the crosslinking agent is selected from N,N-methylenebisacrylamide.

9. The application of CO2 load-responsive self-healing microcapsules as described in claim 1 or 2 in concrete repair.

10. A self-healing concrete, characterized in that, Contains the CO2-loaded, responsive, self-healing microcapsules as described in claim 1 or 2.

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