Zr-BTB gel with self-healing capability and preparation method thereof

Abstract

The invention discloses a Zr-BTB gel with self-healing ability and a preparation method thereof, and belongs to the field of gel material preparation, and the preparation method comprises the following steps: S1, adding ZrCl4, H3BTB, DMF, formic acid and deionized water into a glass bottle, and dissolving solids through ultrasound to obtain a reaction solution; then putting the mixture into a reaction oven to react and synthesize Zr-BTB nanosheets, centrifugally washing the Zr-BTB nanosheets, and preparing a Zr-BTB nanosheet suspension by using ethanol; and S2, heating the Zr-BTB nanosheet suspension at a constant temperature to volatilize the solvent, and when the content of the Zr-BTB nanosheets is 1wt%-1.5 wt%, preparing the Zr-BTB gel with the self-healing capability. The Zr-BTB gel prepared by the invention shows excellent self-healing ability, and lays a solid foundation for application in the fields of biomedicine, flexible electronics, wearable equipment, soft robots and the like in the future.

Description

Technical Field

[0001] The invention belongs to the field of gel material preparation, and in particular relates to a Zr-BTB gel with self-healing ability and a preparation method thereof. Background Art

[0002] Metal-organic frameworks (MOFs) are a class of porous crystalline materials formed by the self-assembly of metal ions or metal clusters and organic ligands. Zr-BTB, among them, has attracted considerable research attention due to its ultrathinness, ease of synthesis, amenability to surface functionalization, and high stability. MOFs are widely used in catalysis, sensing, gas separation, and water purification.

[0003] Like most MOF materials, Zr-BTB prepared using current technologies is usually in a solid powder state. This state limits its potential in many applications. The current problems faced by powdered MOF materials are as follows: (1) Fine powders may cause dust pollution, threaten the health of operators, and pose a risk of dust explosions; (2) Powdered materials have poor solution processability and are difficult to be directly used in the preparation of gas separation membranes and water purification membranes. Compared with MOF powders, MOF gels can effectively circumvent the powder dust problem that occurs during industrial applications, thereby improving operational safety. The superior solution processability of MOF gels also gives them broader application potential in the fields of gas separation membranes and water purification membranes. In addition, the excellent self-healing ability of MOF gels is also conducive to their future applications in biomedicine, flexible electronics and wearable devices, and soft robotics. Therefore, designing a Zr-BTB gel with self-healing ability is extremely important to meet future application needs. Summary of the Invention

[0004] The present invention aims to solve the defects and shortcomings of existing Zr-BTB powder, such as potential dust pollution, dust explosion risk, poor liquid processability, and lack of self-healing ability, and provide a Zr-BTB gel with self-healing ability and a preparation method thereof.

[0005] A method for preparing a Zr-BTB gel with self-healing ability comprises the following steps:

[0006] Step S1, adding ZrCl4, H3BTB, DMF, formic acid and deionized water into a glass bottle, dissolving the solid by ultrasound to obtain a reaction solution; then placing the solution in a reaction oven to react and synthesize Zr-BTB nanosheets, centrifuging and washing, and then using ethanol to prepare a Zr-BTB nanosheet suspension;

[0007] Step S2: The Zr-BTB nanosheet suspension is heated at a constant temperature to evaporate the solvent. When the Zr-BTB nanosheet content is 1 wt % to 1.5 wt %, a Zr-BTB gel with self-healing ability can be obtained.

[0008] Furthermore, in step S1, in the reactant solution, the molar ratio of ZrCl4 to H3BTB is 0.129:0.068; and the volume ratio of DMF, formic acid, and deionized water is 15:2:2.

[0009] Furthermore, in step S1, the reaction conditions in the reaction oven are set to: 120° C., 24 h.

[0010] Furthermore, in step S1, the ultrasonic condition is 37 kHz for 10 mins.

[0011] Furthermore, in step S1, the centrifugal washing operation includes: sequentially centrifuging the Zr-BTB nanosheet suspension with DMF and ethanol for at least three times, with each washing condition controlled at 4500 rpm for 30 mins.

[0012] Furthermore, in step S2, the concentration of the Zr-BTB nanosheet suspension is 2.5 mg / mL, the constant heating temperature is 80° C., and the heating time is 1.5 h-1.75 h.

[0013] The present invention has the following beneficial effects: It provides a method for preparing a self-healing Zr-BTB gel. Compared to Zr-BTB powder prepared using existing techniques, the Zr-BTB gel prepared by this method not only avoids dust generation in industrial applications and improves operational safety, but also exhibits excellent solution processing properties, facilitating its further application in fields such as gas separation membranes and water purification membranes. Furthermore, the Zr-BTB gel prepared by this method exhibits excellent self-healing properties, laying a solid foundation for future applications in biomedicine, flexible electronics and wearable devices, and soft robotics. Furthermore, the preparation method is simple, environmentally friendly, and safe. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is an AFM image of the Zr-BTB nanosheets obtained in Example 1.

[0015] Figure 2 The figures are pictures of the Zr-BTB gels obtained in Example 1 and Comparative Examples 1-2; wherein, (a) is a picture of the Zr-BTB gel obtained in Comparative Example 1, (b) is a picture of the Zr-BTB gel obtained in Example 1, and (c) is a picture of the Zr-BTB gel obtained in Comparative Example 2.

[0016] Figure 3Graph showing the changes in storage modulus (G') and loss modulus (G'') of the Zr-BTB gel obtained in Example 1 under different shear strains.

[0017] Figure 4 This is a graph showing the change in the nanosheet content in the Zr-BTB suspension with solvent evaporation time.

[0018] Figure 5 Schematic diagram of the experimental process of Example 1. DETAILED DESCRIPTION

[0019] The technical solutions of the present invention are described in detail below through examples, but the protection scope of the present invention is not limited to the examples.

[0020] Example 1

[0021] 1) ZrCl₄ (0.129 mmol), H₃BTB (0.068 mmol), DMF (15 mL), formic acid (2 mL), and deionized water (2 mL) were added to a glass vial. The solid was dissolved by sonication at 37 kHz for 10 min. The vial was placed in a 120°C oven for 24 h. The resulting product (Zr-BTB nanosheets) was washed by centrifugation and then washed three times with DMF and ethanol, respectively. The washed Zr-BTB nanosheets were prepared as a homogeneous suspension in ethanol at a concentration of 2.5 mg / mL for storage. Each wash was performed at 4500 rpm for 30 min.

[0022] 2) Add 10 mL of Zr-BTB suspension to a glass bottle, evaporate the solvent on a heating plate at 80°C, and monitor the change in sample mass by real-time weighing. When the nanosheet content in the sample reaches 1 wt%, heating is stopped to obtain a self-healing Zr-BTB gel.

[0023] Comparative Example 1

[0024] 1) ZrCl₄ (0.129 mmol), H₃BTB (0.068 mmol), DMF (15 mL), formic acid (2 mL), and deionized water (2 mL) were added to a glass vial and the solids were dissolved by sonication. The vial was placed in a 120°C oven for 24 h. The resulting product (Zr-BTB nanosheets) was washed by centrifugation and then washed three times with DMF and ethanol, respectively. The washed Zr-BTB nanosheets were prepared as a homogeneous suspension in ethanol at a concentration of 2.5 mg / mL for storage.

[0025] 2) Add 10 mL of Zr-BTB suspension into a glass bottle and evaporate the solvent on a heating plate at 80°C. Stop heating when the nanosheet content in the sample reaches 0.5 wt%. This will produce a self-healing Zr-BTB gel.

[0026] Comparative Example 2

[0027] 1) ZrCl₄ (0.129 mmol), H₃BTB (0.068 mmol), DMF (15 mL), formic acid (2 mL), and deionized water (2 mL) were added to a glass vial and dissolved by sonication. The vial was placed in a 120°C oven for 24 h. The resulting product (Zr-BTB nanosheets) was washed by centrifugation and then washed three times with DMF and ethanol. The washed Zr-BTB nanosheets were prepared as a homogeneous suspension in ethanol at a concentration of 2.5 mg / mL for storage.

[0028] 2) Add 10 mL of Zr-BTB suspension into a glass bottle and evaporate the solvent on a heating plate at 80°C. Stop heating when the nanosheet content in the sample reaches 2 wt%. This will produce a self-healing Zr-BTB gel.

[0029] Example 1 and Comparative Examples 1-2 were tested and analyzed, and the results are as follows Figure 1-3 The analysis results are as follows:

[0030] 1. Pass Figure 1 Analysis shows that the thickness of the Zr-BTB nanosheets prepared in Example 1 is 1.5 nm, which is similar to the van der Waals size of the Zr6 clusters in Zr-BTB (1.2 nm), indicating that a single-layer nanosheet was successfully prepared.

[0031] 2. Pass Figure 2 Analysis shows that when the content of Zr-BTB nanosheets in the sample is 0.5 wt%, heating is stopped and the sample becomes a flowable liquid state, as shown in Figure 2. Figure 2 As shown in (a); when the Zr-BTB nanosheet content is 1 wt%, the heating is stopped and the sample shows a non-flowable gel state, as shown in Figure 2 As shown in (b); when the content of Zr-BTB nanosheets reaches 2 wt%, part of the gel appears in a dry solid state, as shown in Figure 2 As shown in (c), it shows that the optimal condition is to stop heating when the nanosheet content is 1 wt%.

[0032] 3. Pass Figure 3Analysis shows that the Zr-BTB nanosheet gel prepared in Example 1 exhibits a gel-like state at low shear strain (0.1%). When the shear strain rises to 20%, the gel decomposes and exhibits a liquid-like state. When the shear strain returns to 0.1%, the sample self-heals and re-emerges into a gel-like state. This demonstrates that the preparation method of the present invention can produce Zr-BTB gels with self-healing properties.

[0033] 4. 10 mL of the Zr-BTB suspension prepared in Example 1 was added to a glass bottle, and the solvent was evaporated on a hot plate at 80°C. The content of Zr-BTB nanosheets was controlled by controlling the solvent evaporation time, from the initial suspension (initial Zr-BTB nanosheet concentration 2.5 mg / mL, Zr-BTB nanosheet content 0.33 wt%) to the final nearly completely solid state (evaporation time 3 hours, Zr-BTB nanosheet content 98.04 wt%). Figure 4 The change in the nanosheet content in the sample every 15 minutes as the solvent evaporates is shown.

[0034] When the nanosheet content ranged from 0.33 wt% to 0.78 wt%, the sample appeared as a flowing liquid when the glass bottle was inverted, rather than a gel. However, when the nanosheet content ranged from 1.03 wt% to 1.47 wt% (evaporation time 1.5 h to 1.75 h), the sample exhibited a gel-like state. At a nanosheet content of 2.25 wt% (evaporation time 2 h), the overall volume of the gel decreased, and portions of the gel appeared as a dry solid. Therefore, a nanosheet content between 1 wt% and 1.5 wt% should represent the optimal gel state.

[0035] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to the form and details without departing from the spirit and scope of the present invention.

Claims

1. A method for preparing a Zr-BTB gel with self-healing ability, characterized in that: The steps include: Step S1, adding ZrCl4, H3BTB, DMF, formic acid and deionized water into a glass bottle, dissolving the solid by ultrasound to obtain a reaction solution; then placing the solution in a reaction oven to react and synthesize Zr-BTB nanosheets, centrifuging and washing, and then using ethanol to prepare a Zr-BTB nanosheet suspension; Step S2: The Zr-BTB nanosheet suspension is heated at a constant temperature to evaporate the solvent. When the Zr-BTB nanosheet content is 1 wt% to 1.5 wt%, a Zr-BTB gel with self-healing ability is obtained.

2. The preparation method according to claim 1, characterized in that In step S1, in the reactant solution, the molar ratio of ZrCl4 to H3BTB is 0.129:0.068; and the volume ratio of DMF, formic acid, and deionized water is 15:2:

2.

3. The preparation method according to claim 1, characterized in that In step S1, the reaction conditions in the reaction oven are set to: 120° C., 24 h.

4. The preparation method according to claim 1, characterized in that In step S1, the ultrasonic condition is 37 kHz for 10 mins.

5. The preparation method according to claim 1, characterized in that In step S1, the centrifugal washing operation includes: sequentially centrifuging the Zr-BTB nanosheet suspension with DMF and ethanol for at least three times, with each washing condition controlled at 4500 rpm for 30 mins.

6. The preparation method according to claim 1, characterized in that In step S2, the concentration of the Zr-BTB nanosheet suspension is 2.5 mg / mL, the constant heating temperature is 80° C., and the heating time is 1.5 h to 1.75 h.

7. Zr-BTB gel with self-healing ability prepared according to the preparation method according to any one of claims 1 to 6.

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