A preparation method of ethyl cellulose bicomponent microcapsules based on ZIF-8 modification

Abstract

The application discloses a preparation method of ethyl cellulose double-component microcapsules based on ZIF-8 modification, and self-repairing microcapsules are obtained by preparing ZIF-8 and wrapping, the pore structure of ZIF-8 can provide a larger surface area and pore volume, thereby accommodating more epoxy resin, further increasing the drug loading capacity of the microcapsules, and making the concrete self-repairing effect more durable; ZIF-8 can realize precise release control by adjusting the structure of the wall material, the release rate and timing of the epoxy resin can be adjusted according to the degree of the concrete crack and the need, so that the self-repairing is more accurately realized; ZIF-8 can provide an additional protective layer to protect the epoxy resin from the external environment, and the stability of the epoxy resin in the microcapsules is enhanced, so that the epoxy resin remains active for a long time.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of concrete admixtures, in particular to a preparation method of ethyl cellulose double-component microcapsules based on ZIF-8 modification. BACKGROUND

[0002] Cracks inevitably occur in concrete during service, which affects the structure of buildings and seriously affects the safety of people's lives and property. Artificial repair of concrete consumes a large amount of manpower and material resources, therefore, the self-repairing ability of organisms after being damaged has attracted widespread attention from people, and self-repairing technology has also attracted widespread attention.

[0003] Microcapsule self-repairing technology as a safe and efficient self-repairing technology has made remarkable progress under the efforts of researchers since its appearance. However, the current mainstream microcapsule self-repairing system still has many deficiencies to be overcome. For example, the stability of microcapsules is not high, the environmental toxicity is high, and the slow-release performance of microcapsules is poor, which seriously limits the application of microcapsules.

[0004] Epoxy resin / ethyl cellulose microcapsules as a non-toxic single-component self-repairing strategy have the advantages of high synthesis rate and good slow-release performance, and play an important role in solving the above problems. However, there are still some problems to be solved in the service process of epoxy resin / ethyl cellulose microcapsules. Since the ethyl cellulose is porous and has a slow-release skeleton structure, it can slow down the release of the core material as a wall material. However, too many or large pores will cause the core material to leak out or release too fast. Meanwhile, the poor thermal stability of the epoxy resin / ethyl cellulose microcapsules is also a problem to be solved. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of ethyl cellulose double-component microcapsules based on ZIF-8 modification to solve the above problems. After the ZIF-8 particles are added to the microcapsules, the pore structure of the microcapsules is blocked to some extent, so that the core material can be better and more wrapped in the wall material.

[0006] The application achieves the above-mentioned purpose through the following technical solutions:

[0007] A preparation method of ethyl cellulose double-component microcapsules based on ZIF-8 modification, comprising the following steps:

[0008] Step 1, preparation of ZIF-8 particles;

[0009] Take 100ml of methanol and 100ml of distilled water to obtain solvent 1, take 100ml of methanol as solvent 2, take 2.7g of zinc chloride and add it to solvent 1, take 6.5g of dimethyl imidazole and add it to solvent 2 to obtain solution 1 and solution 2 respectively, c(zinc chloride) = 0.1ml / L, c(dimethyl imidazole) = 0.8ml / L, mix solution 1 and solution 2, stir at room temperature at a speed of 300rpm for 2 hours, then centrifuge at 10000rpm for 10 minutes to obtain a solid, stand at room temperature for 12h, grind into powder and then put into an oven at 50℃ to dry to obtain a dry white solid powder;

[0010] Step 2, preparation of gelatin solution;

[0011] Take 40g of gelatin and 800g of water, mix in a three-necked flask, stir at a speed of 560rpm for 10 minutes under a constant temperature water bath at 60℃, then cool to 30℃ at room temperature;

[0012] Step 3, preparation of ZIF-8 mixed solution;

[0013] Take 15g of ethyl cellulose, 1.5g of ZIF-8, 15g of epoxy resin and 280g of chloromethane solution, mix in a three-necked flask, stir at room temperature at a speed of 650rpm for 10 minutes, and then ultrasonic for 10 minutes to obtain a uniformly dispersed mixture of particles;

[0014] Step 4, preparation of self-repairing microcapsules;

[0015] Mix the solutions of step 2 and step 3 in a three-necked flask, stir at a speed of 800rpm for 1.5 hours under a constant temperature water bath at 30℃, increase the temperature to 42℃, stir at a speed of 650rpm for 2 hours, then keep the speed unchanged and continue to increase the temperature to 45℃ for 1 hour to obtain a microcapsule solution; the solution is divided into two phases after standing, the upper layer is the water phase layer and the lower layer is the microcapsule precipitate; remove the upper water phase, wash the microcapsule precipitate with dichloromethane, and then put it into an oven with a temperature setting of 45℃ for drying for 24h to obtain ZIF-8 modified ethyl cellulose two-component microcapsule powder.

[0016] Further, in step 1, v(methanol):v(water) = 1:1.

[0017] Further, in step 2, m(gelatin):m(water) = 1:20.

[0018] Further, in step 3, m(ethyl cellulose):m(epoxy resin):m(dichloromethane) = 1:1:18.6.

[0019] The beneficial effects of the present application are:

[0020] (1) Greater drug loading capacity: The porous structure of ZIF-8 can provide a larger surface area and pore volume, thus accommodating more epoxy resin, further increasing the drug loading capacity of the microcapsule, making the concrete self-repairing effect more durable.

[0021] (2) More precise release control: ZIF-8 can achieve precise release control by adjusting the structure of the wall material, and can adjust the release rate and timing of the epoxy resin according to the degree of concrete crack and need, thus achieving more precise self-repairing.

[0022] (3) Stability improvement: ZIF-8 can provide an additional protective layer to protect the epoxy resin from external environmental influences, enhancing the stability of the epoxy resin in the microcapsule, keeping it active for a long time. At the same time, MOF has high thermal stability, which can improve the thermal stability of the microcapsule. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0024] Figure 1 The structure diagram of the ZIF-8 modified ethyl cellulose microcapsule of the present application;

[0025] In the figure: 1, main microcapsule; 2, ZIF-8 particles.

[0026] Figure 2 The SEM image of the ZIF-8 particles of the present application;

[0027] Figure 3 Another SEM image of the ZIF-8 particles of the present application; DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0029] Comparative Example 1: for preparing unmodified self-repairing microcapsule, the preparation method comprises the following steps:

[0030] Take 40 g of gelatin and 800 g of water, m(gelatin):m(water) = 1:20, prepare the solution solution, mix in a three-necked flask, stir at 560 rpm under a constant temperature water bath at 60°C for 10 minutes, get transparent viscous oil phase, then cool to 30°C at room temperature.

[0031] Again take 15 g of ethyl cellulose, 15 g of epoxy resin and 280 g of dichloromethane solution, m(ethyl cellulose):m(epoxy resin):m(dichloromethane) = 1:1:18.6, mix in a three-necked flask, stir at room temperature at 650 rpm for 10 min, then ultrasonic for 10 min, make the particles disperse uniformly.

[0032] Mix the above two solutions in a three-necked flask, stir at 800 rpm under a constant temperature water bath at 30°C for 1.5 hours, increase the temperature to 42°C, stir at 650 rpm for 2 hours, then keep the speed unchanged, continue to increase the temperature to 45°C and stir for one hour, get the microcapsule solution. The solution is divided into two phases after standing, the upper layer is the water phase layer, and the lower layer is the microcapsule precipitate. Pour away the upper water phase, wash the microcapsule sediment with dichloromethane, and then put it into an oven with a temperature setting of 45°C for drying for 24 h, to obtain the unmodified ethyl cellulose microcapsule powder product.

[0033] Example 1: Preparation of modified self-repairing microcapsules, the preparation method, comprising the following steps:

[0034] 1) Preparation of ZIF-8 particles

[0035] Take 100 ml of methanol and 100 ml of distilled water to get solvent 1, and 100 ml of methanol as solvent 2, take a certain amount of 2.7 g of zinc chloride into solvent 1 and 6.5 g of dimethyl imidazole into solvent 2 to get solutions 1 and 2, c(zinc chloride) = 0.1 mol / L, c(dimethyl imidazole) = 0.8 mol / L, so that the molar concentration ratio of zinc chloride solution to dimethyl imidazole solution is 1:8, mix the two solutions, stir at room temperature at 300 rpm for 2 hours, then centrifuge at 10000 rpm for 10 minutes to get a solid, stand at room temperature for 12 h, grind into powder and put into an oven at 50°C for drying for 20 minutes to get dry white solid powder.

[0036] 2) Preparation of self-repairing microcapsules

[0037] Take 40 g of gelatin and 800 g of water, m(gelatin):m(water) = 1:20, prepare the solution solution, mix in a three-necked flask, stir at 560 rpm under a constant temperature water bath at 60°C for 10 minutes, get transparent viscous oil phase, then cool to 30°C at room temperature.

[0038] Again, 15 g of ethyl cellulose, 1.5 g of ZIF-8, 15 g of epoxy resin and 280 g of chloromethane solution were weighed, mixed in a three-necked flask, stirred at room temperature at a speed of 650 rpm for 10 min, and then ultrasonically treated for 10 min to make the particles uniformly dispersed.

[0039] The two solutions were mixed in a three-necked flask, stirred at a speed of 800 rpm for 1.5 hours at a constant temperature water bath temperature of 30°C, the speed was increased to 650 rpm for 2 hours at a temperature of 42°C, and then the speed was kept unchanged and the temperature was increased to 45°C for 1 hour to obtain a microcapsule solution. The solution was separated into two phases after standing, the upper layer was the water phase layer, and the lower layer was the microcapsule precipitate. The upper water phase was poured off, the microcapsule precipitate was washed with dichloromethane, and then placed in an oven with a temperature setting of 45°C for drying for 24 h to obtain a ZIF-8 modified ethyl cellulose microcapsule powder product.

[0040] The microcapsules obtained were tested for encapsulation efficiency according to the grinding method, and the test results are shown in Table 1.

[0041] Table 1: Encapsulation efficiency test of the microcapsules prepared in Comparative Examples 1-2

[0042]

[0043] As can be seen from the data in the table, the core material content of the microcapsules modified by adding ZIF-8 particles in Example 1 reached 28%, which is 13% higher than the 15% of the blank group, and the encapsulation efficiency is increased by 86.7% compared with Comparative Example 1, indicating that ZIF-8 particles can achieve higher core material loading capacity. There are pores on the surface of the microcapsules in Comparative Example 1, which reduces the core material encapsulation rate of the microcapsules, while the microcapsules in Example 1 have a certain plugging effect on the pore structure of the capsules (as shown in FIG. 1) after adding ZIF-8 particles, so that the core material can be better and in larger amounts encapsulated in the wall material. Figure 1

[0044] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims. In addition, it should be noted that in the above specific embodiments, various specific technical features can be combined in any appropriate manner without contradiction, in order to avoid unnecessary repetition, the present application will not further describe various possible combinations. In addition, various embodiments of the present application can also be combined in any manner, as long as it does not violate the idea of the present application, it should also be considered as disclosed by the present application.​

Claims

1. A method for preparing ethyl cellulose bi-component microcapsules based on ZIF-8 modification, characterized in that, The method comprises the following steps: Step 1, preparation of ZIF-8 particles; 100 ml of methanol and 100 ml of distilled water are mixed to obtain solvent 1, 100 ml of methanol is taken as solvent 2, 2.7 g of zinc chloride is weighed and added to solvent 1, 6.5 g of dimethyl imidazole is added to solvent 2 to obtain solution 1 and solution 2 respectively, c(zinc chloride) = 0.1 ml / L, c(dimethyl imidazole) = 0.8 ml / L, the solution 1 and the solution 2 are mixed, stirred at a speed of 300 rpm at room temperature for 2 hours, then centrifuged at 10000 rpm for 10 minutes to obtain a solid, which is placed in an oven at 50 DEG C after being ground into a powder and standing at room temperature for 12 hours to obtain a dry white solid powder; Step 2, preparation of a gelatin solution; 40 g of gelatin and 800 g of water are weighed and mixed in a three-necked flask, stirred at a speed of 560 rpm in a constant temperature water bath at 60 DEG C for 10 minutes to obtain a transparent viscous solution, and then cooled to 30 DEG C at room temperature; Step 3, preparation of a ZIF-8 mixed solution; 15 g of ethyl cellulose, 1.5 g of ZIF-8, 15 g of epoxy resin and 280 g of chloromethane solution are weighed and mixed in a three-necked flask, stirred at a speed of 650 rpm at room temperature for 10 minutes, and then ultrasonically treated for 10 minutes to obtain a uniformly dispersed mixture of particles; Step 4, preparation of self-repairing microcapsules; The solutions of steps 2 and 3 are mixed in a three-necked flask, stirred at a speed of 800 rpm in a constant temperature water bath at 30 DEG C for 1.5 hours, heated to 42 DEG C and stirred at a speed of 650 rpm for 2 hours, then the speed is kept unchanged and the temperature is further increased to 45 DEG C for 1 hour to obtain a microcapsule solution; the solution is separated into two phases after standing, the upper layer is an aqueous phase layer and the lower layer is a microcapsule precipitate; the upper aqueous phase is removed, the microcapsule precipitate is washed with dichloromethane and then placed in an oven with a temperature setting of 45 DEG C for drying for 24 hours to obtain ZIF-8 modified ethyl cellulose two-component microcapsule powder.

2. The method for preparing ethyl cellulose bi-component microcapsules based on ZIF-8 modification according to claim 1, characterized in that, In step 1, v(methanol):v(water) = 1:

1.

3. The method for preparing a two-component microcapsule based on ZIF-8 modified ethyl cellulose as described in claim 1, characterized in that, In step 2, m(gelatin):m(water) = 1:

20.

4. The method for preparing a two-component microcapsule based on ZIF-8 modified ethyl cellulose as described in claim 1, characterized in that, In step 3, m(ethyl cellulose):m(epoxy resin):m(dichloromethane) = 1:1:18.6.

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