Quercetin-containing rapid self-healing conductive hydrogel and preparation method thereof

Abstract

The invention provides rapid self-healing conductive hydrogel containing quercetin and a preparation method of the rapid self-healing conductive hydrogel, can be used for strain sensing, and belongs to the technical field of functional polymer materials. The preparation method comprises the following steps: firstly, dissolving quercetin in a glycerol / water mixed solution, mixing with a branched chain polyethyleneimine (PEI) aqueous solution and an acrylic monomer (AA), and introducing aluminum ions (Al < 3 + >); then adding an initiator and a cross-linking agent to initiate acrylic acid polymerization, and meanwhile, carrying out Schiff base reaction on ketone groups in quercetin molecules and amino groups in PEI to form dynamic imine bonds; the obtained polyacrylic acid (PAA) network is combined with positively charged PEI through electrostatic interaction, and Al < 3 + > and carboxyl of PAA form a metal coordination bond. Dynamic imine bonds formed in the hydrogel, electrostatic interaction, hydrogen bonds and metal coordination bonds jointly endow the hydrogel with rapid self-healing ability. The hydrogel has good mechanical properties, stable conductivity provided by Al < 3 + >, and the characteristic of rapid self-healing after being damaged by puncture, cutting and the like. The flexible strain sensor can generate obvious and stable resistance change after being stimulated by external strain, has high strain sensing sensitivity, is suitable for the field of flexible strain sensing, prolongs the service life, and conforms to the concept of green materials.

Description

Technical Field

[0001] The present invention relates to the technical field of functional polymer materials, and in particular to a quercetin-containing fast self-healing conductive hydrogel constructed by quercetin, branched polyethyleneimine, acrylic acid and aluminum ions through the synergistic action of multiple dynamic bonds, and a preparation method thereof. Background Art

[0002] Hydrogels are a class of polymers with a three-dimensional network structure composed of hydrophilic polymer chains physically or chemically cross-linked. Hydrogels can absorb thousands of times their own weight in water without breaking. They also possess unique properties such as high transparency, good flexibility, excellent biocompatibility, and responsiveness to external stimuli. Consequently, hydrogels are widely used in various fields. However, due to limitations such as the matrix material, traditional hydrogels often suffer from shortcomings such as poor mechanical properties, lack of electrical conductivity, and limited performance. Furthermore, in complex and changing external environments, hydrogels are inevitably susceptible to mechanical damage such as bumps, punctures, and ruptures. This can significantly shorten the hydrogel's service life. Therefore, it is of great significance to construct and prepare a conductive hydrogel with a wide operating range and self-healing capabilities.

[0003] Self-healing hydrogels can self-repair after mechanical damage, restoring the hydrogel's mechanical properties, sensing properties, and external morphology to their pre-damage state. Self-healing bonding can be divided into dynamic covalent bonds (imine bonds, acylhydrazone bonds, borate bonds, and disulfide bonds, etc.) and dynamic non-covalent bonds (hydrophobic bonds, hydrogen bonds, metal coordination bonds, and host-guest interactions, etc.). Self-healing hydrogels often suffer from problems such as poor mechanical properties, insufficient self-healing efficiency, long self-healing time, and lack of electrical conductivity. Therefore, it is possible to consider using multiple dynamic bonds to bond together to construct a conductive hydrogel with a rapid white healing effect.

[0004] Quercetin is a flavonoid compound extracted from plants rich in catechol structure, which has anti-inflammatory, antioxidant and adhesion capabilities. However, the insolubility of quercetin in water greatly limits its application in the field of hydrogels. Dissolving quercetin in glycerol and then mixing glycerol with water can solve this problem. Quercetin contains ketone groups, which can react with amino-containing compounds through Schiff base to form dynamic imine bonds, so that the hydrogel can obtain self-healing ability. Amino-containing compounds are often positively charged, and they can generate electrostatic interactions when combined with negatively charged acrylic acid. In addition, by introducing aluminum ions (Al 3+ ) as charge carriers to provide ion conduction pathways, while Al 3+ Aluminum ions can form dynamic metal coordination bonds with the carboxyl groups on the polyacrylic acid chain, and the aluminum ions themselves can significantly enhance the conductivity of the hydrogel. Therefore, a conductive hydrogel with excellent mechanical properties, rapid self-healing, and high strain sensitivity can be constructed. Summary of the Invention

[0005] Purpose of the invention: The present invention provides a quercetin-containing fast self-healing conductive hydrogel and a preparation method thereof. The hydrogel prepared by this method can quickly and efficiently self-heal when damaged, and the preparation process is relatively environmentally friendly, and is applied in the field of flexible strain sensing.

[0006] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] 1) Weigh a certain amount of branched polyethyleneimine and dissolve it in a certain volume of deionized water, stirring for a certain period of time to obtain a polyethyleneimine solution;

[0008] 2) Weighing a certain amount of quercetin and dissolving it in a certain volume of glycerol, then adding a certain volume of deionized water and stirring for a certain period of time to obtain a quercetin solution;

[0009] 3) mixing the polyethyleneimine solution obtained in step 1) and the quercetin solution obtained in step 2) with a certain volume of acrylic acid in the same container, adding a certain amount of aluminum chloride hexahydrate, and continuing to stir for a certain period of time to form a mixed precursor solution containing aluminum ions;

[0010] 4) In an ice-water bath, adding a certain amount of ammonium persulfate and a certain amount of N,N′-methylenebisacrylamide to the mixed precursor solution obtained in step 3), stirring for a certain time to mix evenly, then pouring the mixed solution into a mold, placing it in a water bath and heating it for a certain time to perform a polymerization reaction, thereby forming a fast self-healing conductive hydrogel with polyacrylic acid as the network skeleton and cross-linked by multiple dynamic interactions such as dynamic Schiff base bonds between quercetin ketone groups and branched polyethyleneimine amino groups, electrostatic interactions between polyacrylic acid carboxyl groups and branched polyethyleneimine amino groups, and metal coordination bonds between aluminum ions and polyacrylic acid carboxyl groups.

[0011] In the step 1), the molecular weight of polyethyleneimine is 10,000-70,000, the dosage is 0.05-0.3 g, the volume of deionized water is 1-6 ml, and the stirring time is 0.5-3 hours.

[0012] In the step 2), the amount of quercetin is 0.005-0.03 g, the amount of glycerol is 1-5 ml, the volume of deionized water is 1-4 ml, and the stirring time is 1-3 hours.

[0013] In the step 3), the amount of acrylic acid used is 1-5 ml, the amount of aluminum chloride hexahydrate used is 0.05-0.4 g, and the stirring time is 0.5-4 hours.

[0014] In the step 4), the amount of ammonium persulfate used is 0.02-0.1 g, the amount of N,N′-methylenebisacrylamide used is 0.001-0.01 g, the stirring time is 30-120 seconds, the heating temperature of the water bath is 45-70 degrees Celsius, and the thermal initiation time is 1-5 hours.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1) The present invention provides a quercetin-containing fast self-healing conductive hydrogel and a preparation method thereof. The preparation process does not require complex equipment, is simple to operate, has good reproducibility, and the obtained hydrogel exhibits good mechanical properties.

[0017] 2) An innovative glycerol / water mixed solvent system was used to effectively dissolve and evenly disperse hydrophobic quercetin within the hydrogel system. The keto groups in the quercetin molecule were fully utilized to undergo a reversible Schiff base reaction with the abundant primary amino groups on the branched polyethyleneimine molecular chain, forming a dynamic imine bond. This reversible covalent bond, combined with the strong electrostatic interaction between the polyacrylic acid carboxyl groups and the polyethyleneimine amino groups, enabled the hydrogel to completely self-heal within 2 hours after damage (with a healing efficiency of 100%).

[0018] 3) The quercetin-containing fast self-healing conductive hydrogel prepared by the present invention has conductive ability by introducing aluminum chloride hexahydrate. The prepared hydrogel has excellent stability and can detect various small to large strains such as human joint movement and muscle contraction in real time and stably. It has application potential in the fields of flexible strain sensing, wearable electronic devices, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The stress-strain curve and basic mechanical properties of the quercetin-containing fast self-healing conductive hydrogel prepared in Example 1 of the present invention are shown;

[0020] Figure 2 This is a macroscopic display of the self-healing performance of the quercetin-containing fast self-healing conductive hydrogel prepared in Example 1 of the present invention;

[0021] Figure 3 The quercetin-containing fast self-healing conductive hydrogel prepared in Example 1 of the present invention monitors micro-movements of different parts of the human body.

[0022] The performance of the quercetin-containing fast self-healing conductive hydrogel prepared in Example 1 was tested as follows:

[0023] 1) Pictures showing the mechanical properties of hydrogels

[0024] Figure 1The stress-strain curve and mechanical properties of the hydrogel prepared in Example 1 are shown in the figure. As shown, the hydrogel has a tensile strength of 93 kPa and an elongation at break of 860%. Furthermore, the hydrogel sensor can withstand twisting, tangling, and penetration by sharp objects.

[0025] 2) Image showing the self-healing properties of hydrogels

[0026] Figure 2 This image shows the self-healing of the hydrogel prepared in Example 1. As shown, the hydrogel, dyed and cut into multiple small squares, then pieced together, heals itself into a single piece after 15 minutes. Furthermore, the small squares show no tendency to separate after stretching, demonstrating the hydrogel's excellent, rapid self-healing ability.

[0027] 3) Image of hydrogel sensing performance for detecting activities in different parts of the human body

[0028] Figure 3 This image shows the hydrogel prepared in Example 1 being tested using an LCR bridge to measure the resistance change caused by finger bending and eyebrow raising. As shown, the hydrogel's resistance changes can accurately detect the frequency and degree of finger bending, eyebrow raising, and frowning. DETAILED DESCRIPTION

[0029] Example 1

[0030] 1) Weigh 0.1 g of branched polyethyleneimine (relative molecular weight = 25000) and dissolve it in 2.5 ml of deionized water. Stir for 1 hour to obtain a polyethyleneimine solution.

[0031] 2) Weigh 0.01 g of quercetin and dissolve it in 3 ml of glycerol. Then add 2 ml of deionized water and stir for 2 hours to obtain a quercetin solution.

[0032] 3) The polyethyleneimine solution obtained in step 1) and the quercetin solution obtained in step 2) were mixed with 2.5 ml of acrylic acid in the same beaker, 0.2 g of aluminum chloride hexahydrate was added, and stirring was continued for 1 hour to form a mixed precursor solution containing aluminum ions;

[0033] 4) In an ice-water bath, 0.05 g of ammonium persulfate and 0.0025 g of N,N′-methylenebisacrylamide were added to the mixed precursor solution obtained in step 3) and stirred for 60 seconds to mix the solution evenly. The solution was then poured into a polytetrafluoroethylene mold, placed in a 55°C water bath, and heated for 2 hours for polymerization to obtain a fast self-healing conductive hydrogel.

[0034] Example 2

[0035] 1) Weigh 0.2 g of branched polyethyleneimine (relative molecular weight = 60,000) and dissolve it in 5 ml of deionized water. Stir for 1.5 hours to obtain a polyethyleneimine solution.

[0036] 2) Weigh 0.015 g of quercetin and dissolve it in 3.5 ml of glycerol. Then add 3.5 ml of deionized water and stir for 1 hour to obtain a quercetin solution.

[0037] 3) mixing the polyethyleneimine solution obtained in step 1) and the quercetin solution obtained in step 2) with 3 ml of acrylic acid in the same beaker, adding 0.1 g of aluminum chloride hexahydrate, and continuing stirring for 2.5 hours to form a mixed precursor solution containing aluminum ions;

[0038] 4) In an ice-water bath, 0.08 g of ammonium persulfate and 0.004 g of N,N′-methylenebisacrylamide were added to the mixed precursor solution obtained in step 3) and stirred for 90 seconds to mix the solution evenly. The solution was then poured into a polytetrafluoroethylene mold, placed in a 60°C water bath, and heated for 1.5 hours for polymerization to obtain a fast self-healing conductive hydrogel.

[0039] Example 3

[0040] 1) Weigh 0.15 g of branched polyethyleneimine (relative molecular weight = 10,000) and dissolve it in 3 ml of deionized water. Stir for 0.5 hour to obtain a polyethyleneimine solution.

[0041] 2) Weigh 0.005 g of quercetin and dissolve it in 1.5 ml of glycerol. Then add 1.5 ml of deionized water and stir for 1.5 hours to obtain a quercetin solution.

[0042] 3) The polyethyleneimine solution obtained in step 1) and the quercetin solution obtained in step 2) were mixed with 4 ml of acrylic acid in the same beaker, 0.15 g of aluminum chloride hexahydrate was added, and stirring was continued for 2 hours to form a mixed precursor solution containing aluminum ions;

[0043] 4) In an ice-water bath, 0.03 g of ammonium persulfate and 0.0015 g of N,N′-methylenebisacrylamide were added to the mixed precursor solution obtained in step 3) and stirred for 50 seconds to mix the solution evenly. The solution was then poured into a polytetrafluoroethylene mold, placed in a 50°C water bath, and heated for 3 hours for polymerization to obtain a fast self-healing conductive hydrogel.

[0044] Example 4

[0045] 1) Weigh 0.3 g of branched polyethyleneimine (relative molecular weight = 30,000) and dissolve it in 4 ml of deionized water. Stir for 2.5 hours to obtain a polyethyleneimine solution.

[0046] 2) Weigh 0.02 g of quercetin and dissolve it in 2 ml of glycerol. Then add 3 ml of deionized water and stir for 3 hours to obtain a quercetin solution.

[0047] 3) mixing the polyethyleneimine solution obtained in step 1) and the quercetin solution obtained in step 2) with 2 ml of acrylic acid in the same beaker, adding 0.3 g of aluminum chloride hexahydrate, and continuing stirring for 3 hours to form a mixed precursor solution containing aluminum ions;

[0048] 4) In an ice-water bath, 0.09 g of ammonium persulfate and 0.003 g of N,N′-methylenebisacrylamide were added to the mixed precursor solution obtained in step 3) and stirred for 45 seconds to mix the solution evenly. The solution was then poured into a polytetrafluoroethylene mold, placed in a 70°C water bath, and heated for 2.5 hours for polymerization to obtain a fast self-healing conductive hydrogel.

[0049] Example 5

[0050] 1) Weigh 0.25 g of branched polyethyleneimine (relative molecular weight = 40,000) and dissolve it in 2 ml of deionized water. Stir for 2 hours to obtain a polyethyleneimine solution.

[0051] 2) Weigh 0.025 g of quercetin and dissolve it in 2.5 ml of glycerol. Then add 4 ml of deionized water and stir for 2.5 hours to obtain a quercetin solution.

[0052] 3) mixing the polyethyleneimine solution obtained in step 1) and the quercetin solution obtained in step 2) with 3.5 ml of acrylic acid in the same beaker, adding 0.25 g of aluminum chloride hexahydrate, and continuing stirring for 1.5 hours to form a mixed precursor solution containing aluminum ions;

[0053] 4) In an ice-water bath, 0.06 g of ammonium persulfate and 0.005 g of N,N′-methylenebisacrylamide were added to the mixed precursor solution obtained in step 3) and stirred for 100 seconds to mix the solution evenly. The solution was then poured into a polytetrafluoroethylene mold, placed in a 65°C water bath, and heated for 3.5 hours for polymerization to obtain a fast self-healing conductive hydrogel.

[0054] Several specific embodiments of the present invention have been described above. However, it should be noted that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the essence of the present invention.

Claims

1. A method for preparing a fast self-healing conductive hydrogel containing quercetin, characterized in that: The following steps are involved: 1) Weigh a certain amount of branched polyethyleneimine and dissolve it in a certain volume of deionized water, stirring for a certain period of time to obtain a polyethyleneimine solution; 2) Weighing a certain amount of quercetin and dissolving it in a certain volume of glycerol, then adding a certain volume of deionized water and stirring for a certain period of time to obtain a quercetin solution; 3) mixing the polyethyleneimine solution obtained in step 1) and the quercetin solution obtained in step 2) with a certain volume of acrylic acid in the same container, adding a certain amount of aluminum chloride hexahydrate, and continuing to stir for a certain period of time to form a mixed precursor solution containing aluminum ions; 4) In an ice-water bath, adding a certain amount of ammonium persulfate and a certain amount of N,N′-methylenebisacrylamide to the mixed precursor solution obtained in step 3), stirring for a certain time to mix evenly, then pouring the mixed solution into a mold, placing it in a water bath and heating it for a certain time to perform a polymerization reaction, thereby forming a fast self-healing conductive hydrogel with polyacrylic acid as the network skeleton and cross-linked by multiple dynamic interactions such as dynamic Schiff base bonds between quercetin ketone groups and branched polyethyleneimine amino groups, electrostatic interactions between polyacrylic acid carboxyl groups and branched polyethyleneimine amino groups, and metal coordination bonds between aluminum ions and polyacrylic acid carboxyl groups.

2. The method for preparing the quercetin-containing fast self-healing conductive hydrogel according to claim 1, characterized in that: In the step 1), the molecular weight of polyethyleneimine is 10,000-70,000, the dosage is 0.05-0.3 g, the volume of deionized water is 1-6 ml, and the stirring time is 0.5-3 hours.

3. The method for preparing the quercetin-containing fast self-healing conductive hydrogel according to claim 1, wherein: In the step 2), the amount of quercetin is 0.005-0.03 g, the amount of glycerol is 1-5 ml, the volume of deionized water is 1-4 ml, and the stirring time is 1-3 hours.

4. The method for preparing the quercetin-containing fast self-healing conductive hydrogel according to claim 1, wherein: In the step 3), the amount of acrylic acid used is 1-5 ml, the amount of aluminum chloride hexahydrate used is 0.05-0.4 g, and the stirring time is 0.5-4 hours.

5. The method for preparing the quercetin-containing fast self-healing conductive hydrogel according to claim 1, wherein: In the step 4), the amount of ammonium persulfate used is 0.02-0.1 g, the amount of N,N′-methylenebisacrylamide used is 0.001-0.01 g, the stirring time is 30-120 seconds, the heating temperature of the water bath is 45-70 degrees Celsius, and the thermal initiation time is 1-5 hours.

6. A quercetin-containing fast-healing conductive hydrogel prepared by the preparation method according to any one of claims 1 to 5, which has excellent mechanical and conductive properties, rapid self-healing ability, and high strain sensing sensitivity, and can be used in the field of flexible strain sensing.

Images