Temperature-sensitive microcapsule with internal maintenance and anti-corrosion functions as well as preparation method and application of temperature-sensitive microcapsule

Abstract

The invention relates to the technical field of concrete additive equipment, in particular to a temperature-sensitive microcapsule with internal curing and anti-corrosion functions as well as a preparation method and application thereof, and the preparation method comprises the following steps: adding an anti-corrosion curing material into deionized water to obtain an inner core solution; dissolving an initiator in deionized water to obtain an initiator solution; dissolving a monomer material and a cross-linking agent in deionized water, and stirring under the protection of nitrogen until the monomer material and the cross-linking agent are completely dissolved to obtain a shell solution; and respectively pumping the inner core solution and the shell solution into different channels of a micro-fluidic chip, dripping liquid drops obtained in the chip into an initiator solution under the protection of nitrogen, reacting in a constant-temperature water bath, cooling to room temperature, and centrifuging to obtain the temperature-sensitive microcapsule. By adopting the steps, the obtained temperature-sensitive microcapsules are uniform in morphology and high in stability, and the performance of concrete can be improved by the anti-corrosion curing material released at the phase change temperature and the dehydrated shell.

Description

Technical Field

[0001] The invention relates to the technical field of concrete additives, and in particular to a temperature-sensitive microcapsule with internal curing and anti-corrosion functions, and a preparation method and application thereof. Background Art

[0002] As one of the most widely used materials in the field of civil engineering, concrete is in great demand in engineering. However, the reserves of traditional concrete materials in marine engineering are too small to meet the needs of marine engineering, and the cost of transporting traditional materials inland is relatively expensive. Therefore, choosing sea sand, which has abundant reserves in marine engineering, as an alternative material for concrete fine aggregate can build marine engineering according to local conditions. From the perspective of reducing the water pressure of local people and saving construction costs, it is very necessary to use abundant seawater to participate in the mixing of concrete, which is of great significance to accelerate the construction of marine engineering.

[0003] Reinforced concrete is the most widely used building material at present. It refers to a composite material formed by adding steel mesh, steel plate or fiber to concrete to work together to improve the mechanical properties of concrete. However, the corrosion of steel bars in reinforced concrete can cause problems such as degradation of concrete structure performance and premature failure. Summary of the invention

[0004] The purpose of the present invention is to provide a thermosensitive microcapsule with both internal curing and anti-corrosion functions and a preparation method and application thereof. The obtained thermosensitive microcapsule has uniform morphology and high stability. The anti-corrosion curing material released at the phase change temperature and the shell after dehydration can improve the performance of concrete.

[0005] To achieve the above object, the present invention provides a method for preparing a thermosensitive microcapsule having both internal curing and anti-corrosion functions, comprising the following steps: S1. Adding the anti-corrosion curing material into deionized water to obtain an inner core solution; S2, dissolving the initiator in deionized water to obtain an initiator solution; S3, dissolving the monomer material and the cross-linking agent in deionized water, stirring under nitrogen protection until completely dissolved, to obtain a shell solution; S4. The inner core solution obtained in S1 and the outer shell solution obtained in S3 are pumped into different channels of the microfluidic chip respectively. Under nitrogen protection, the liquid droplets obtained in the chip are dripped into the initiator solution in S2. The reaction is carried out in a constant temperature water bath. After cooling to room temperature, centrifugation is performed to obtain thermosensitive microcapsules.

[0006] Preferably, in S1, the anti-corrosion curing material includes one or more of calcium nitrate, molybdate and sodium benzoate.

[0007] Preferably, in S2, the initiator includes one or more of ammonium persulfate, azobisisobutyronitrile, and potassium persulfate.

[0008] Preferably, in S3, the monomer material includes one or more of N-isopropylacrylamide, acrylic acid, acrylamide, methyl acrylate and ethyl acrylate.

[0009] Preferably, in S3, the molar ratio of the monomer material to the cross-linking agent is 1:0.005-0.5.

[0010] Preferably, in S4, the pumping speed ratio of the inner core solution to the outer shell solution is 1:2-5.

[0011] Preferably, in S4, the constant temperature water bath is maintained at 20-70° C. for 10-20 h.

[0012] The thermosensitive microcapsules are prepared by the method for preparing thermosensitive microcapsules with both internal curing and anti-corrosion functions.

[0013] The above-mentioned thermosensitive microcapsule with both internal curing and anti-corrosion functions is used in the preparation of seawater and sea sand ultra-high performance concrete.

[0014] Preferably, the addition amount of the temperature-sensitive microcapsules is 0.01-1% of the mass of the concrete.

[0015] Therefore, the present invention adopts the above-mentioned temperature-sensitive microcapsule with both internal curing and anti-corrosion functions and its preparation method and application, and its beneficial effects are: 1. The thermosensitive microcapsules prepared by the present invention have uniform morphology and high stability. At the phase change temperature (32-40°C), the anti-corrosion curing materials released can effectively increase the alkalinity inside the concrete or be adsorbed on the surface of the steel bars to form a protective oxide film, thereby effectively improving the concrete's resistance to chloride ion corrosion; 2. During the exothermic process of concrete hydration, its internal temperature rises. When it reaches the phase transition temperature of the thermosensitive microcapsule, the poly N-isopropylacrylamide molecules in the outer shell shrink and dehydrate. Then, other polymer segments polymerized with poly N-isopropylacrylamide participate in the hydration process of concrete and form a cross-interpenetrating network structure with the hydration products in the concrete, which promotes the further increase of the density of the internal structure of the concrete and helps to improve the mechanical properties of the concrete material.

[0016] The technical solution of the present invention is further described in detail below through embodiments. DETAILED DESCRIPTION

[0017] A method for preparing a thermosensitive microcapsule having both internal curing and anti-corrosion functions comprises the following steps: S1. Adding the anti-corrosion curing material into deionized water to obtain an inner core solution; S2, dissolving the initiator in deionized water to obtain an initiator solution; S3, dissolving the monomer material and the cross-linking agent in deionized water, stirring under nitrogen protection until completely dissolved, to obtain a shell solution; S4. The inner core solution obtained in S1 and the outer shell solution obtained in S3 are pumped into different channels of the microfluidic chip respectively. Under nitrogen protection, the liquid droplets obtained in the chip are dripped into the initiator solution in S2. The reaction is carried out in a constant temperature water bath. After cooling to room temperature, centrifugation is performed to obtain thermosensitive microcapsules.

[0018] In S1, the anti-corrosion curing material includes one or more of calcium nitrate, molybdate and sodium benzoate.

[0019] In S2, the initiator includes one or more of ammonium persulfate, azobisisobutyronitrile, and potassium persulfate.

[0020] In S3, the monomer material includes one or more of N-isopropylacrylamide, acrylic acid, acrylamide, methyl acrylate and ethyl acrylate.

[0021] The polymer in the shell is one of poly N-isopropylacrylamide or poly N-isopropylacrylamide-acrylic acid copolymer, poly N-isopropylacrylamide-acrylamide copolymer, poly N-isopropylacrylamide-methyl acrylate copolymer and poly N-isopropylacrylamide-ethyl acrylate copolymer. By polymerizing N-isopropylacrylamide with other monomers, the temperature-sensitive function is realized while further improving the mechanical properties of concrete.

[0022] In S3, the molar ratio of the monomer material to the cross-linking agent is 1:0.005-0.5.

[0023] In S4, the pumping speed ratio of the inner core solution to the outer shell solution is 1:2-5. By adjusting the pumping speed ratio, thermosensitive microcapsules with different core-shell ratios are obtained, thereby adjusting the amount of anti-corrosion curing material.

[0024] In S4, the constant temperature water bath is maintained at 20-70°C for 10-20 hours.

[0025] The present invention is further described below in conjunction with embodiments. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs. The above-mentioned features or features mentioned in the specific examples mentioned in the present invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0026] Example 1 S1. Mix 5 g of anti-corrosion curing materials calcium nitrate and molybdate in a mass ratio of 1:1 and add into 100 mL of deionized water to obtain an inner core solution.

[0027] S2. Dissolve 1 g of initiator ammonium persulfate in 100 mL of deionized water to obtain an initiator solution.

[0028] S3. 15 g of monomer material N-isopropylacrylamide and cross-linking agent N,N'-methylenebisacrylamide were mixed at a molar ratio of 1:0.005 and dissolved in 100 mL of deionized water. The mixture was stirred under nitrogen protection until completely dissolved to obtain a shell solution.

[0029] S4, the inner core solution obtained in S1 and the outer shell solution obtained in S3 were pumped into different channels of the microfluidic chip, the pumping speed of the inner core solution was 550 μL / h, and the pumping speed of the outer shell solution was 1650 μL / h. Under nitrogen protection, the droplets obtained in the chip were added into the initiator solution in S2, reacted in a constant temperature water bath at 60°C for 15 hours, cooled to room temperature and centrifuged to obtain thermosensitive microcapsules.

[0030] Example 2 S1. Add 5 g of anti-corrosion curing materials calcium nitrate and sodium benzoate in a mass ratio of 1:0.5 into 100 mL of deionized water to obtain an inner core solution.

[0031] S2. Dissolve 1 g of initiator azobisisobutyronitrile in 100 mL of deionized water to obtain an initiator solution.

[0032] S3. 15 g of monomer material (N-isopropylacrylamide and acrylic acid mixed in a molar ratio of 2:1) and cross-linking agent N,N'-methylenebisacrylamide in a molar ratio of 1:0.1 were mixed and dissolved in 100 mL of deionized water. The mixture was stirred under nitrogen protection until completely dissolved to obtain a shell solution.

[0033] S4, the inner core solution obtained in S1 and the outer shell solution obtained in S3 were pumped into different channels of the microfluidic chip, the pumping speed of the inner core solution was 600 μL / h, and the pumping speed of the outer shell solution was 1560 μL / h. Under nitrogen protection, the droplets obtained in the chip were added into the initiator solution in S2, reacted in a constant temperature water bath at 60°C for 17 hours, cooled to room temperature and centrifuged to obtain thermosensitive microcapsules.

[0034] Example 3 S1. Add 5 g of anti-corrosion curing materials calcium nitrate and sodium benzoate in a mass ratio of 1:0.8 into 100 mL of deionized water to obtain an inner core solution.

[0035] S2. Dissolve 1 g of initiator ammonium persulfate in 100 mL of deionized water to obtain an initiator solution.

[0036] S3. 15 g of monomer material (N-isopropylacrylamide and methyl acrylate mixed in a molar ratio of 1:1) and cross-linking agent N,N'-methylenebisacrylamide in a molar ratio of 1:0.15 were mixed and dissolved in 100 mL of deionized water. The mixture was stirred under nitrogen protection until completely dissolved to obtain a shell solution.

[0037] S4, the inner core solution obtained in S1 and the outer shell solution obtained in S3 were pumped into different channels of the microfluidic chip, the pumping speed of the inner core solution was 700 μL / h, and the pumping speed of the outer shell solution was 2800 μL / h. Under nitrogen protection, the droplets obtained in the chip were added into the initiator solution in S2, and reacted in a constant temperature water bath at 60°C for 18 hours, cooled to room temperature and centrifuged to obtain thermosensitive microcapsules.

[0038] Example 4 S1. Mix 5 g of anti-corrosion curing materials calcium nitrate and molybdate in a mass ratio of 1:0.5 and add into 100 mL of deionized water to obtain an inner core solution.

[0039] S2. Dissolve 1 g of initiator ammonium persulfate in 100 mL of deionized water to obtain an initiator solution.

[0040] S3. 15 g of monomer material (N-isopropylacrylamide and methyl acrylate mixed in a molar ratio of 2:1) and cross-linking agent N,N'-methylenebisacrylamide in a molar ratio of 1:0.1 were mixed and dissolved in 100 mL of deionized water. The mixture was stirred under nitrogen protection until completely dissolved to obtain a shell solution.

[0041] S4, the inner core solution obtained in S1 and the outer shell solution obtained in S3 were pumped into different channels of the microfluidic chip, the pumping speed of the inner core solution was 800 μL / h, and the pumping speed of the outer shell solution was 3000 μL / h. Under nitrogen protection, the droplets obtained in the chip were added into the initiator solution in S2, reacted in a constant temperature water bath at 60°C for 17 hours, cooled to room temperature and centrifuged to obtain thermosensitive microcapsules.

[0042] Example 5 S1. Add 5 g of anti-corrosion curing material molybdate into 100 mL of deionized water to obtain an inner core solution.

[0043] S2. Dissolve 1 g of initiator in 100 mL of azobisisobutyronitrile and deionized water to obtain an initiator solution.

[0044] S3. 15 g of monomer material (N-isopropylacrylamide and ethyl acrylate mixed in a molar ratio of 2:1) and cross-linking agent N,N'-methylenebisacrylamide in a molar ratio of 1:0.3 were mixed and dissolved in 100 mL of deionized water. The mixture was stirred under nitrogen protection until completely dissolved to obtain a shell solution.

[0045] S4, the inner core solution obtained in S1 and the outer shell solution obtained in S3 were pumped into different channels of the microfluidic chip, the pumping speed of the inner core solution was 500 μL / h, and the pumping speed of the outer shell solution was 2500 μL / h. Under nitrogen protection, the droplets obtained in the chip were added into the initiator solution in S2, and reacted in a constant temperature water bath at 60°C for 15 hours, cooled to room temperature and centrifuged to obtain thermosensitive microcapsules.

[0046] Application Example 1 The temperature-sensitive microcapsules in Example 1 were applied to the preparation of seawater and sea sand ultra-high performance concrete, and the addition amount of the temperature-sensitive microcapsules was 0.01% of the mass of the concrete.

[0047] Application Example 2 The temperature-sensitive microcapsules in Example 2 were applied to the preparation of seawater and sea sand ultra-high performance concrete, and the amount of the temperature-sensitive microcapsules added was 0.05% of the mass of the concrete.

[0048] Application Example 3 The temperature-sensitive microcapsules in Example 3 were applied to the preparation of seawater and sea sand ultra-high performance concrete, and the addition amount of the temperature-sensitive microcapsules was 0.1% of the mass of the concrete.

[0049] Application Example 4 The temperature-sensitive microcapsules in Example 4 were applied to the preparation of seawater and sea sand ultra-high performance concrete, and the amount of the temperature-sensitive microcapsules added was 0.2% of the mass of the concrete.

[0050] Application Example 5 The temperature-sensitive microcapsules in Example 5 were applied to the preparation of seawater and sea sand ultra-high performance concrete, and the addition amount of the temperature-sensitive microcapsules was 1% of the mass of the concrete.

[0051] Comparative Example 1 S1. Dissolve the initiator ammonium persulfate in deionized water to obtain an initiator solution.

[0052] S2. Mix the monomer material N-isopropylacrylamide and the cross-linking agent N,N'-methylenebisacrylamide in a molar ratio of 1:0.1, dissolve in deionized water, and stir under nitrogen protection until completely dissolved to obtain a shell solution.

[0053] S3, the shell solution obtained in S2 was pumped into the corresponding channels of the microfluidic chip at a pumping speed of 3000 μL / h. Under nitrogen protection, the droplets obtained in the chip were added into the initiator solution in S1, reacted in a constant temperature water bath at 60°C for 17 hours, cooled to room temperature and centrifuged to obtain microcapsules.

[0054] The temperature-sensitive microcapsules in Comparative Example 1 were applied to the preparation of seawater and sea sand ultra-high performance concrete, and the amount of the temperature-sensitive microcapsules added was 0.2% of the mass of the concrete.

[0055] Test Case The concrete blocks prepared at different temperatures (25° C., 36° C.) in Examples 1-5 and Comparative Example 1 were subjected to corrosion resistance tests and salt water immersion resistance tests. The test results are shown in Table 1.

[0056] Table 1. Corrosion resistance data of concrete in application examples 1-5 and comparative example 1 ; 20 concrete samples of the same size and specification were selected from Application Examples 1-5 and Comparative Example 1, and the compressive strength test was performed. The average values ​​were recorded as shown in Table 2.

[0057] Table 2. Compressive strength data of application examples 1-5 and comparative example 1 ; It can be seen from the data in Table 1 and Table 2 that the microcapsules provided by the present invention release the anti-corrosion curing material at the phase transition temperature (32-40°C), effectively improving the corrosion resistance of concrete. In addition, after the anti-corrosion curing material is released from the temperature-sensitive shell, it can react with the unhydrated cement particles in the concrete to increase the mechanical properties of the concrete.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for preparing a thermosensitive microcapsule having both internal curing and anti-corrosion functions, characterized in that: The following steps are included: S1. Adding the anti-corrosion curing material into deionized water to obtain an inner core solution; S2, dissolving the initiator in deionized water to obtain an initiator solution; S3, dissolving the monomer material and the cross-linking agent in deionized water, stirring under nitrogen protection until completely dissolved, to obtain a shell solution; S4. The inner core solution obtained in S1 and the outer shell solution obtained in S3 are pumped into different channels of the microfluidic chip respectively. Under nitrogen protection, the liquid droplets obtained in the chip are dripped into the initiator solution in S2. The reaction is carried out in a constant temperature water bath. After cooling to room temperature, centrifugation is performed to obtain thermosensitive microcapsules.

2. The method for preparing a thermosensitive microcapsule having both internal curing and anti-corrosion functions according to claim 1, characterized in that: In S1, the anti-corrosion curing material includes one or more of calcium nitrate, molybdate and sodium benzoate.

3. The method for preparing a thermosensitive microcapsule having both internal curing and anti-corrosion functions according to claim 1, characterized in that: In S2, the initiator includes one or more of ammonium persulfate, azobisisobutyronitrile, and potassium persulfate.

4. The method for preparing a thermosensitive microcapsule having both internal curing and anti-corrosion functions according to claim 1, characterized in that: In S3, the monomer material includes one or more of N-isopropylacrylamide, N-vinylcaprolactam, acrylic acid, acrylamide, methyl acrylate and ethyl acrylate.

5. The method for preparing a thermosensitive microcapsule having both internal curing and anti-corrosion functions according to claim 1, characterized in that: In S3, the molar ratio of the monomer material to the cross-linking agent is 1:0.005-0.

5.

6. The method for preparing a thermosensitive microcapsule having both internal curing and anti-corrosion functions according to claim 1, characterized in that: In S4, the pumping speed ratio of the inner core solution and the outer shell solution is 1:2-5.

7. The method for preparing a thermosensitive microcapsule having both internal curing and anti-corrosion functions according to claim 1, characterized in that: In S4, the constant temperature water bath is maintained at 20-70°C for 10-20 hours.

8. Thermosensitive microcapsules prepared according to the method for preparing thermosensitive microcapsules with both internal curing and anti-corrosion functions according to any one of claims 1 to 7.

9. The use of a thermosensitive microcapsule having both internal curing and anti-corrosion functions according to claim 8, characterized in that: Used in the preparation of seawater and sea sand ultra-high performance concrete.

10. The use of a thermosensitive microcapsule having both internal curing and anti-corrosion functions according to claim 9, characterized in that: The addition amount of thermosensitive microcapsules is 0.01-1% of the mass of concrete.