A method for preparing a multi-responsive self-healing gel

Abstract

This invention discloses a method for preparing a multi-responsive self-healing gel, comprising the following steps: firstly, synthesizing 4-hydroxyazobenzene, the azobenzene crosslinking agent shown in formula (1), and the 3-acrylamidophenylboronic acid functional monomer; then, dissolving β-cyclodextrin and 3-acrylamidophenylboronic acid in an alkaline solution, sequentially adding the compound of formula (1) and the acrylamide monomer, and finally, performing free radical polymerization at room temperature under the action of an oxidation-reduction initiation system composed of ammonium persulfate and tetramethylethylenediamine to obtain the gel. The preparation conditions of this invention are mild and the operation is simple. The resulting gel can undergo reversible gel-sol phase transition under ultraviolet / visible light irradiation, pH changes, or temperature rises and falls, while exhibiting good self-healing properties, sensitive response, and good cycle stability. It has broad application prospects in the fields of drug controlled release, biosensing, and intelligent actuators.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a method for preparing a multi-responsive self-healing gel. Background Technology

[0002] Smart gels, as three-dimensional network polymer materials capable of reversible responses to external environmental stimuli such as temperature, pH, light, electric fields, and specific molecules, exhibit significant intelligent properties in behaviors such as swelling and contraction, shape change, and phase transition. Therefore, they have broad application prospects in drug delivery, tissue scaffolds, biosensing, and soft actuators. With the increasing complexity of application scenarios, single response modes are no longer sufficient to meet practical needs, making the development of hydrogel systems integrating multiple responses an important research direction. Furthermore, hydrogel materials are prone to structural damage due to external forces during practical use. Without self-healing capabilities, their service life and reliability will be significantly affected. Therefore, endowing hydrogels with self-healing functions is of great significance for improving the practicality and durability of materials.

[0003] Currently, common strategies for constructing multi-response and self-healing gels typically integrate multiple functional units into the same system through physical blending, chemical copolymerization, or the construction of interpenetrating networks. However, these methods often face problems such as complex preparation processes, interference between different response mechanisms, insufficient synergy of responses, and poor material uniformity. Chinese patent CN121550472A discloses an antibacterial thermosensitive hydrogel, its preparation method, and its applications. This hydrogel can complete the gel-sol transition at 4–60°C and exhibits thermosensitivity, providing a new approach for developing novel medical dressings for treating wounds infected with drug-resistant bacteria. Chinese patent CN116285188A discloses a side-chain azobenzene polymer gel, its preparation method, and the construction of a chiral photoswitch. This gel can also utilize the gel-sol transition to achieve visual recognition of enantiomeric molecules, providing a new strategy for expanding the preparation of side-chain azobenzene polymers and the construction of chiral photoswitches. Chinese patent CN113248742A discloses a pH- and light-responsive natural polysaccharide hydrogel and its preparation method. This gel collapses into a sol state in an alkaline solution with a pH of 10-14 or under 365nm ultraviolet light irradiation, exhibiting dual pH and light responsiveness. Chinese patent CN103145920A discloses a method for preparing a temperature, pH, and ultraviolet light-responsive semi-interpenetrating network nanocomposite hydrogel. The prepared hydrogel uses nano-lithium diatomite crosslinked monomers as the gel framework and cellulose macromolecules as semi-interpenetrating macromolecules, responding to changes in temperature, pH, and ultraviolet light to achieve volume transformation, showing potential application in drug sustained-release. Chinese patent CN109966558A discloses an injectable smart responsive hydrogel, its preparation method, and its applications. A dynamic crosslinked network is constructed through a Schiff base reaction, enabling the hydrogel to self-repair after breakage, while also possessing pH sensitivity and redox responsiveness.

[0004] While the aforementioned patents have achieved multiple responses or self-healing functions, there are no reports of integrating the triple response of light, pH, and temperature with self-healing functions into a single homogeneous gel network. Constructing a structurally stable, responsive, self-healing, and easily tunable homogeneous gel network, and achieving its controllable preparation under mild conditions, remains a key technological challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a multi-responsive self-healing gel that is relatively simple to prepare and can synergistically respond to three external stimuli: light, pH, and temperature.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing a multi-responsive self-healing gel, the process route of which is as follows:

[0008] ;

[0009] .

[0010] Specifically, the following steps are included:

[0011] (1) In an ice bath environment of 0-5℃, aniline was added to concentrated hydrochloric acid solution, mixed and sodium nitrite solution was added dropwise. After reacting for 1-1.5 h, a mixed solution of phenol and sodium hydroxide was added dropwise and the reaction was continued for 1-3 h to obtain compound 4-hydroxyazobenzene;

[0012] (2) 4-hydroxyazobenzene and 1,6-dibromohexane were subjected to a Williamson ether condensation reaction in the presence of a basic catalyst to obtain the compound shown in formula (1);

[0013] (3) Under the protection of ice bath and nitrogen at 0-5℃, 3-aminophenylboronic acid monohydrate was dissolved in alkaline solution, and acryloyl chloride solution was added dropwise while stirring. After the reaction was continued for 0.5-1.5 h, hydrochloric acid solution was added dropwise to terminate the reaction and adjust the pH. The solid was precipitated to obtain compound 3-acrylamidophenylboronic acid.

[0014] (4) Under the entire nitrogen atmosphere, β-cyclodextrin and 3-acrylamidophenylboronic acid were first dissolved in an alkaline solution and stirred for 4-8 h. Then, 5-15 times the volume of ice ethanol was added, and a solid was precipitated to obtain compound (2) 3-acrylamidophenylboronic acid β-cyclodextrin ester. After completely dissolving it in 1-5 mL of borax-sodium hydroxide buffer solution with pH=9, compound (1) dissolved in N-methylpyrrolidone was added and reacted for 4-6 h. Subsequently, acrylamide monomer dissolved in deionized water was added, and ammonium persulfate and tetramethylethylenediamine prepared in advance were injected as initiation systems. The initiation polymerization reaction was carried out at room temperature. After reacting for 12-48 h, the obtained product was soaked in deionized water to remove unreacted monomers and impurities, thereby obtaining the multi-responsive self-healing gel.

[0015] The structural formula of compound (1) is as follows:

[0016]

[0017] Equation (1);

[0018] The structural formula of compound (2) is as follows:

[0019]

[0020] Equation (2).

[0021] Preferably, in step (1), the molar ratio of aniline to sodium nitrite is 1:1 to 1.2; the molar ratio of aniline to phenol is 1:1 to 1.2; the molar ratio of aniline to sodium hydroxide is 1:2.4 to 3.2; and the molar ratio of aniline to concentrated hydrochloric acid is 1:3.5 to 4.

[0022] Preferably, in step (1), the mixed solution of phenol and sodium hydroxide is prepared by dissolving phenol and sodium hydroxide in distilled water, and after complete dissolution, adjusting the pH to 8-9 with dilute acid or dilute alkali; wherein the molar ratio of phenol to sodium hydroxide is 1:2-3.

[0023] Preferably, in step (2), the 4-hydroxyazobenzene is dissolved in N,N-dimethylformamide, and 1,6-dibromohexane solution is added dropwise in the presence of an alkaline catalyst. The reaction is carried out at 100℃~110℃ for 24 h, and the compound of formula (1) is obtained by extraction and column chromatography purification. The synthetic route is as follows:

[0024] .

[0025] Preferably, in step (2), the molar ratio of 4-hydroxyazobenzene to 1,6-dibromohexane is 1:0.5 to 1; the alkaline catalyst is potassium carbonate and a catalytic amount of potassium iodide, wherein the molar ratio of 4-hydroxyazobenzene to potassium carbonate is 1:5 to 10, and the molar ratio of 4-hydroxyazobenzene to potassium iodide is 1:0.1.

[0026] Preferably, in step (3), the molar ratio of 3-aminophenylboronic acid monohydrate to acryloyl chloride is 1:1 to 2.

[0027] Preferably, in step (3), the addition of hydrochloric acid solution is to adjust the pH of the reaction system to 1-2 so that the target product is fully precipitated in the form of a white solid; wherein, the molar ratio of 3-aminophenylboronic acid monohydrate to hydrochloric acid is 1:10-15.

[0028] Preferably, in step (4), the initiation system is a redox initiation system composed of ammonium persulfate and tetramethylethylenediamine, and the total amount of the initiation system is 1% to 3% of the total mass of all polymerizable monomers in the reaction system.

[0029] Preferably, in step (4), the molar ratio of the compound of formula (1), β-cyclodextrin, 3-acrylamidophenylboronic acid and acrylamide is 1-2:2-4:2-4:2020-2690.

[0030] The design principle of this invention is as follows: A self-healing gel network that responds to three stimuli—light, pH, and temperature—is constructed by utilizing the synergistic effect of host-guest recognition and dynamic covalent bonds. Using the compound of formula (1) as the photoresponsive unit, reversible photocontrolled behavior is achieved through its host-guest inclusion interaction with β-cyclodextrin. Under ultraviolet light irradiation, azobenzene changes from trans to cis, significantly reducing its binding ability with cyclodextrin, leading to host-guest dissociation. Under visible light irradiation, azobenzene reverts to the trans configuration, and the host-guest interaction reforms, thus achieving reversible regulation of the photoresponse. By introducing 3-acrylamidophenylboronic acid, its borate group undergoes a reversible esterification reaction with the vicinal diol structure on β-cyclodextrin, forming a dynamic covalent borate ester bond compound of formula (2). This borate ester bond promotes ester bond formation under alkaline conditions and accelerates hydrolysis under acidic conditions, achieving a pH-stimulated response. Meanwhile, the borate ester bond also endows the gel with temperature responsiveness. Increasing the temperature will disrupt the equilibrium state of the borate ester bond, causing it to move towards dissociation and resulting in a decrease in crosslinking density; decreasing the temperature will facilitate the reformation of the borate ester bond, achieving a reversible sol-gel transition.

[0031] Beneficial effects: Compared with the prior art, the present invention has significant advantages:

[0032] I. This invention integrates the photoresponsive host-guest interaction of azobenzene-cyclodextrin, the pH-responsive phenylboronic acid ester bond, and the thermosensitivity of the polymer network, achieving a highly efficient and synergistic response to three stimuli: light, pH, and temperature. By changing the feeding ratio of compound (1), β-cyclodextrin, 3-acrylamidophenylboronic acid, and acrylamide, the density of dynamic interactions and the degree of chemical crosslinking in the gel network can be precisely controlled, thereby adjusting the response sensitivity.

[0033] Second, the preparation conditions of this invention are mild, and the key steps are carried out at low temperature or room temperature. The final gelation is initiated at room temperature, which avoids the damage of sensitive groups by high temperature and helps to maintain the activity of each functional group. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the light / pH / temperature responsive gel-sol of the present invention, wherein (a) is the sol state after ultraviolet light irradiation, (b) is the initial gel state, (c) is the sol state after heating, and (d) is the sol state when the ambient pH drops below 7;

[0035] Figure 2 Here are the 1H NMR spectra of the compounds, where (a) is the 1H NMR spectrum of compound (1) and (b) is the 1H NMR spectrum of compound (2).

[0036] Figure 3The UV-Vis absorption spectra of the compound of formula (1) are shown, where (a) is after UV lamp irradiation and (b) is after LED visible light irradiation.

[0037] Figure 4 SEM image of the gel obtained in Example 1;

[0038] Figure 5 The viscosity change curve of the gel obtained in Example 1 under alternating photothermal and different pH cycles (number of cycles n=5).

[0039] Figure 6 This is a schematic diagram of the self-healing process of the gel obtained in Example 1. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0041] Example 1

[0042] (1) Synthesis of 4-hydroxyazobenzene: 6.0 mL of concentrated hydrochloric acid and 60 mL of ice water were added to a 250 mL three-necked flask and cooled to 0 °C in an ice bath. Aniline (1.86 g, 20 mmol) was added with stirring and dissolved. After dissolution, a solution of sodium nitrite (1.42 g, 21 mmol) dissolved in 10 mL of water was slowly added dropwise, keeping the temperature below 5 °C. After the addition was complete, the reaction continued for 1 hour. Phenol (1.90 g, 20 mmol) and sodium hydroxide (1.92 g, 48 mmol) were dissolved in 30 mL of water, and the pH was adjusted to 8.5 with dilute hydrochloric acid and pre-cooled. This mixture was slowly added dropwise to the above diazonium salt solution. After the addition was complete, the ice bath was removed, and the reaction was allowed to proceed at room temperature for 2 hours. The mixture was filtered, the filter cake was washed with water until neutral, and dried to give about 3.2 g of an orange-red solid, with a yield of about 80%.

[0043] (2) Synthesis of compound (1): The product from the previous step, 4-hydroxyazobenzene (0.98 g, 5.0 mmol), potassium carbonate (6.93 g, 50 mmol), and potassium iodide (85 mg, 0.5 mmol), were added to a 100 mL round-bottom flask. 80 mL of anhydrous DMF was added, and 1,6-dibromohexane (0.385 mL) solution was added dropwise with stirring. The mixture was heated to 105 °C and reacted for 24 hours. After cooling, the reaction solution was poured into 200 mL of ice water, extracted with ethyl acetate, washed with saturated brine, dried over anhydrous sodium sulfate, and finally dried under vacuum at 40 °C to obtain the orange-red target product.

[0044] (3) Synthesis of 3-acrylamidophenylboronic acid: In a 100 mL three-necked flask, 1.72 g (10 mmol) of 3-aminophenylboronic acid monohydrate and 20 mL of 1 M NaOH aqueous solution were added. The mixture was cooled to 0 °C in an ice bath under nitrogen protection. Acryloyl chloride solution (1.6 mL, 20 mmol) was slowly added dropwise over approximately 30 minutes with vigorous stirring. The reaction was continued for 1 hour. After the reaction was complete, the pH was carefully adjusted to 1 with 6 M hydrochloric acid, resulting in the formation of a large amount of white precipitate. After standing in an ice bath for 1 hour, the precipitate was filtered. The filter cake was washed with a small amount of ice water and dried under vacuum to obtain approximately 1.2 g of a white powdery product.

[0045] (4) Preparation of multi-response self-healing gel: β-cyclodextrin (0.046 g, 0.04 mmol), 3-acrylamidophenylboronic acid (8.2 mg, 0.04 mmol), and 2 mL of borax-sodium hydroxide buffer solution (pH=9) were added sequentially to a glass bottle and magnetically stirred for 4 hours at room temperature. The compound of formula (1) (approximately 10 mg, approximately 0.02 mmol) was dissolved in 4 mL of N-methylpyrrolidone (NMP). After the β-cyclodextrin was completely dissolved, this NMP solution was added to the glass bottle, and the reaction continued for 6 hours. Subsequently, a solution of acrylamide (3.5 g, 50 mmol) dissolved in 3 mL of deionized water was added. Finally, a freshly prepared aqueous solution of APS (20 mg) and TMEDA (30 μL) (0.5 mL) was rapidly injected, and the mixture was allowed to stand at 25°C for 24 hours to form a gel.

[0046] like Figure 1 The diagram shown is a schematic of the light / pH / temperature responsive gel-sol prepared in Example 1. Figure 1 (a) and Figure 1 As shown in (b), after irradiation with 365 nm ultraviolet light for 4 h, a gel-to-sol transition occurred; after irradiation with visible light for 4 h, the gel was also reconstructed. Figure 1 (b) and Figure 1 As shown in (c), when the temperature rises to approximately 70 °C, the gel structure softens into a sol state; after the system cools to room temperature, the sol-to-gel reversal is achieved. Figure 1 (b) and Figure 1 As shown in (d), acetic acid solution was added to the gel sample to adjust the pH to 4.0. At this point, the gel gradually changed to a sol state. Then, triethylamine solution was added to the system to adjust the pH to 10.0, and the sol changed to a gel state.

[0047] like Figure 2As shown in (a), this is the 1H NMR spectrum of compound (1) from Example 1. 1 In the HNMR spectrum, the characteristic peaks at chemical shifts of 6.83 ppm, 7.13 ppm, 7.55 ppm, and 7.86 ppm belong to the aromatic hydrogens of azobenzene. The signals at 1.23 ppm and 1.53 ppm belong to the characteristic peaks of methylene-linked hydrogens. The signal at 4.2 ppm belongs to the methylene proton (-O-CH2-) directly bonded to an oxygen atom. Figure 2 As shown in (b), the 1H NMR spectrum of compound (2) in Example 1 shows the characteristic peak at 3.32 ppm, which is attributed to hydrogen atoms at carbon positions a and c; the characteristic peak at 3.62 ppm, which is attributed to hydrogen atoms at carbon positions b, d, and q; the peak at 4.46 ppm, which is the active hydrogen of the hydroxyl group at positions f and g; the characteristic peak at 4.83 ppm, which is attributed to hydrogen atoms at carbon position e; the signals at 5.69 ppm, 6.26 ppm, and 6.44 ppm, which are attributed to protons at the double bonds at positions o, n, and m of the acryloyl group; the signal at 10.06 ppm, which is the active hydrogen of the -NH- group of the amide group at position l; and the multiplets at 7.27~7.88 ppm, which are attributed to the aromatic hydrogens at positions h, i, j, and k of the benzene ring.

[0048] like Figure 3 As shown in (a), the UV-Vis absorption spectrum of compound (1) in this example is obtained. Under continuous irradiation with 365 nm UV light, the characteristic absorption peak of azobenzene changes significantly and is located near 350 nm, which is attributed to the trans configuration π–π * The absorption peak intensity gradually decreased with increasing irradiation time; simultaneously, the n–π peak at 450 nm, belonging to the cis configuration, was observed. * The absorption peak gradually increased. Compound (1), after being irradiated with ultraviolet light for 120 s, was then irradiated with visible light, such as... Figure 3 As shown in (b), a reversal of the spectral change can be observed, with the n–π absorption peak of the cis configuration gradually weakening and the π–π absorption peak of the trans configuration gradually recovering.

[0049] like Figure 4 The image shown is a SEM image of the gel prepared in Example 1. Figure 4 (a) and Figure 4 (b) shows SEM images at different magnifications, revealing that the gel is filled with pores with uniform pore size distribution, forming a dense honeycomb network.

[0050] like Figure 5As shown, the cyclic stability test of the gel prepared in Example 1 was conducted. The viscosity of the gel was recorded when it was subjected to sequential irradiation with 365 nm ultraviolet light, irradiation with visible light, cycling at temperatures between 25°C and 70°C, and cycling under different pH conditions. The experimental data showed that after five complete cycles, the viscosity of the gel did not decrease significantly, exhibiting good reversible response performance and fatigue resistance.

[0051] like Figure 6 The image shows the results of a self-healing performance test on the gel prepared in Example 1. The hydrogel was cut into two parts with a knife, and after the cut surfaces were in close contact, they were left to stand at room temperature for 10 minutes, and the cut surfaces healed well. A shaking test was then performed on the healed hydrogel, and it was not observed to separate from the cut surface again or fall off.

[0052] Example 2

[0053] The preparation steps were the same as in Example 1, except that 0.49 g (2.5 mmol) of 4-hydroxyazobenzene was reacted with 0.19 mL (1.25 mmol) of 1,6-dibromohexane, the temperature was raised to 105 °C, and the reaction was carried out for 24 hours to obtain an orange-red solid with a yield of about 68%.

[0054] The gel prepared in this embodiment responds to three stimuli: light, pH, and temperature.

[0055] Example 3

[0056] The preparation steps were the same as in Example 1, except that: 3-aminophenylboronic acid monohydrate (1.72 g, 10 mmol) was added, acryloyl chloride (0.8 mL, 10 mmol) was slowly added dropwise, and the product was dried under vacuum to obtain a white powder with a yield of about 61%.

[0057] The gel prepared in this embodiment responds to three stimuli: light, pH, and temperature.

[0058] Example 4

[0059] The preparation steps were the same as in Example 1, except that β-cyclodextrin (0.024 g, 0.02 mmol), 3-acrylamidophenylboronic acid (4.1 mg, 0.02 mmol) from Example 1, and compound (10 mg, 0.02 mmol) were added and allowed to stand at 25°C for 24 hours to form a gel. No significant light response was observed under ultraviolet light irradiation, but pH and temperature responses were observed.

[0060] Comparative Example 1

[0061] The preparation steps were the same as in Example 1, except that the reaction time in step (2) was shortened to 12 hours, the resulting orange-red target product was not the compound of formula (1), and the prepared multi-response self-healing gel did not exhibit the expected photoresponsiveness.

[0062] Comparative Example 2

[0063] The preparation steps are the same as in Example 1, except that in step (4), the amount of acrylamide is adjusted to 0.5 g (7.0 mmol). The prepared gel is a viscous liquid with extremely low mechanical strength and cannot maintain its intact shape.

[0064] Comparative Example 3

[0065] The preparation steps are the same as in Example 1, except that the amount of acrylamide in step (4) is adjusted to 10.0 g (140.8 mmol). The prepared gel is hard and brittle and loses the swelling properties of hydrogel.

Claims

1. A method for preparing a multi-responsive self-healing gel, characterized in that, Includes the following steps: (1) In an ice bath environment of 0-5℃, aniline was added to concentrated hydrochloric acid solution, mixed and sodium nitrite solution was added dropwise. After reacting for 1-1.5 h, a mixed solution of phenol and sodium hydroxide was added dropwise and the reaction was continued for 1-3 h to obtain compound 4-hydroxyazobenzene; (2) 4-hydroxyazobenzene and 1,6-dibromohexane were subjected to a Williamson ether condensation reaction in the presence of a basic catalyst to obtain the compound shown in formula (1); (3) Under the protection of ice bath and nitrogen at 0-5℃, 3-aminophenylboronic acid monohydrate was dissolved in alkaline solution, and acryloyl chloride solution was added dropwise while stirring. After the reaction was continued for 0.5-1.5 h, hydrochloric acid solution was added dropwise to terminate the reaction and adjust the pH. The solid was precipitated to obtain compound 3-acrylamidophenylboronic acid. (4) Under the entire nitrogen atmosphere, β-cyclodextrin and 3-acrylamidophenylboronic acid were first dissolved in an alkaline solution and stirred for 4-8 h. Then, 5-15 times the volume of ice ethanol was added, and a solid was precipitated to obtain compound (2) 3-acrylamidophenylboronic acid β-cyclodextrin ester. After completely dissolving it in 1-5 mL of borax-sodium hydroxide buffer solution with pH=9, compound (1) dissolved in N-methylpyrrolidone was added and reacted for 4-6 h. Subsequently, acrylamide monomer dissolved in deionized water was added, and ammonium persulfate and tetramethylethylenediamine prepared in advance were injected as initiation systems. The initiation polymerization reaction was carried out at room temperature. After reacting for 12-48 h, the obtained product was soaked in deionized water to remove unreacted monomers and impurities, thereby obtaining the multi-responsive self-healing gel. The structural formula of compound (1) is as follows: Equation (1); The structural formula of compound (2) is as follows: Equation (2).

2. The method for preparing the multi-responsive self-healing gel according to claim 1, characterized in that, In step (1), the molar ratio of aniline to sodium nitrite is 1:1 to 1.2; the molar ratio of aniline to phenol is 1:1 to 1.2; the molar ratio of aniline to sodium hydroxide is 1:2.4 to 3.2; and the molar ratio of aniline to concentrated hydrochloric acid is 1:3.5 to 4.

3. The method for preparing the multi-responsive self-healing gel according to claim 1, characterized in that, In step (1), the mixed solution of phenol and sodium hydroxide is prepared by dissolving phenol and sodium hydroxide in distilled water, and after complete dissolution, adjusting the pH to 8-9; wherein the molar ratio of phenol to sodium hydroxide is 1:2-3.

4. The method for preparing the multi-responsive self-healing gel according to claim 1, characterized in that, In step (2), the 4-hydroxyazobenzene was dissolved in N,N-dimethylformamide, and 1,6-dibromohexane solution was added dropwise in the presence of an alkaline catalyst. The reaction was carried out at 100℃~110℃ for 24 h to obtain the compound of formula (1). The synthetic route is as follows: 。 5. The method for preparing the multi-responsive self-healing gel according to claim 1, characterized in that, In step (2), the molar ratio of 4-hydroxyazobenzene to 1,6-dibromohexane is 1:0.5 to 1; the alkaline catalyst comprises potassium carbonate and potassium iodide, wherein the molar ratio of 4-hydroxyazobenzene to potassium carbonate is 1:5 to 10, and the molar ratio of 4-hydroxyazobenzene to potassium iodide is 1:0.

1.

6. The method for preparing the multi-responsive self-healing gel according to claim 1, characterized in that, In step (3), the molar ratio of 3-aminophenylboronic acid monohydrate to acryloyl chloride is 1:1 to 2.

7. The method for preparing the multi-responsive self-healing gel according to claim 1, characterized in that, In step (3), the addition of hydrochloric acid solution is to adjust the pH of the reaction system to 1-2 so that the target product precipitates out in the form of a white solid; wherein, the molar ratio of 3-aminophenylboronic acid monohydrate to hydrochloric acid is 1:10-15.

8. The method for preparing the multi-responsive self-healing gel according to claim 1, characterized in that, In step (4), the initiation system is a redox initiation system composed of ammonium persulfate and tetramethylethylenediamine, and the total amount of the initiation system is 1% to 3% of the total mass of all polymerizable monomers in the reaction system.

9. The method for preparing the multi-responsive self-healing gel according to claim 1, characterized in that, In step (4), the molar ratio of the compound of formula (1), β-cyclodextrin, 3-acrylamidophenylboronic acid and acrylamide is 1~2:2~4:2~4:2020~2690.

Images