Preparation method of lignin-based self-healing material based on dynamic coordination crosslinking

Abstract

The application provides a preparation method of a lignin-based self-repairing material based on dynamic coordination crosslinking, and comprises the following steps: lignin prepolymer preparation: after epoxy lignin is dissolved, an epoxy lignin solution is obtained, the epoxy lignin solution is modified by refluxing and aminating through an amino-triazole compound, and an amino-triazole compound modified epoxy lignin prepolymer is obtained; sebacic acid prepolymer preparation: after epoxy long-chain diacid is dissolved, an epoxy long-chain diacid solution is obtained, the epoxy long-chain diacid solution is cooled in an ice bath, and then modified by refluxing and aminating through an amino-triazole compound, and an amino-triazole compound modified epoxy sebacic acid prepolymer is obtained; the amino-triazole compound modified epoxy lignin prepolymer and the amino-triazole compound modified epoxy sebacic acid prepolymer are dissolved in a solvent according to a set molar ratio, a metal ion solution is added for coordination crosslinking to obtain a liquid, the liquid is introduced into a mold, and drying is performed, and a metal ion coordination crosslinked lignin-based self-repairing material is obtained.

Description

Technical Field

[0001] This invention belongs to the field of self-healing materials technology, specifically relating to a method for preparing lignin-based self-healing materials based on dynamic coordination crosslinking. Background Technology

[0002] Lignin is a naturally occurring polymer abundant in nature, widely distributed in coniferous, broad-leaved, and grassy plants. Primarily found in the xylem of plants, lignin is a major component of the xylem cell wall. Through the formation of a three-dimensional network, it imparts strength and rigidity to the xylem, enabling it to support the plant structure. Lignin is abundant in nature, and due to the strong regenerative capacity of plant resources, it possesses the characteristics of sustainable utilization. However, in actual production, as a byproduct of the cellulose industry, lignin is not fully utilized. Large quantities are directly discarded into the environment or burned for heat energy, causing enormous waste of natural resources and polluting the environment. While lignin has a complex molecular structure, it contains active groups such as hydroxyl and carboxyl groups, allowing it to participate in various chemical reactions. Furthermore, the benzene rings and polycyclic rings in lignin endow it with high rigidity and thermal stability, enabling modification to prepare various high-performance products, thus possessing significant application value in production.

[0003] Triazole heterocycles, due to their ease of leveraging various non-covalent interactions, have been widely used in constructing supramolecular systems for supramolecular recognition and biomimetic simulations. Furthermore, triazole heterocycles are a class of heterocyclic compounds with broad biological activities, finding wide applications in synthesis, catalysis, pharmaceuticals, pesticides, life sciences, functional materials, and molecular biology. Supramolecular structures built from triazole rings have shown great potential as self-healing materials, attracting significant attention in the materials science field and providing a new avenue for their development.

[0004] Current self-healing materials suffer from several drawbacks. Materials based on strong reversible bonds exhibit excellent mechanical properties but poor repair capabilities; conversely, materials based on weak reversible bonds require relatively mild repair conditions but suffer from inferior mechanical properties. Therefore, developing a self-healing material that combines both excellent mechanical properties and superior repair capabilities is of paramount importance. Summary of the Invention

[0005] This invention utilizes renewable and inexpensive lignin as a raw material to prepare lignin-based self-healing materials based on dynamic coordination crosslinking. Using epoxidized lignin with a rigid structure and epoxidized long-chain diacid with a flexible structure as the matrix, a lignin-based self-healing material based on dynamic coordination crosslinking is prepared through the coordination crosslinking effect of triazole and metal ions.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: The preparation method of lignin-based self-healing materials based on dynamic coordination crosslinking includes the following steps. Preparation of lignin prepolymer: The epoxidized lignin solution after dissolution was modified by reflux ammoniation with amino-triazole compounds to obtain amino-triazole modified epoxidized lignin prepolymer; Preparation of sebacic acid prepolymer: The solution of epoxidized long-chain diacid after dissolution was cooled in an ice bath and then modified by reflux ammoniation with amino-triazole compounds to obtain amino-triazole modified epoxidized sebacate prepolymer. Preparation of lignin-based self-healing materials: Amino-triazole modified epoxidized lignin prepolymer and amino-triazole modified epoxidized sebacic acid prepolymer are dissolved in a solvent at a set molar ratio, and then a metal ion solution is added for coordination crosslinking to obtain a liquid. The mixture is stirred and poured into a mold, evaporated at room temperature, and then dried to obtain a metal ion coordinated crosslinked lignin-based self-healing material.

[0007] Furthermore, it also includes the preparation of epoxidized lignin, the specific steps of which are as follows: Epoxidized lignin is obtained by reacting propane with lignin solution under reflux conditions in the presence of tetrabutylammonium bromide solution and sodium hydroxide catalysis.

[0008] Furthermore, in the preparation of the epoxidized lignin, tetrabutylammonium bromide is added in two parts. The first part is added together with epichlorohydrin and stirred under reflux. The second part is the remaining tetrabutylammonium bromide and sodium hydroxide dissolved in water and added dropwise to the reflux liquid.

[0009] Furthermore, in the first and second additions, the mass ratio of the tetrabutylammonium bromide to lignin is 1:10-1:5.

[0010] Furthermore, it also includes the preparation of epoxidized long-chain diacids, the specific steps of which are as follows: In the presence of tetrabutylammonium bromide solution and sodium hydroxide as catalysts, propane epoxide reacts with a long-chain diacid solution to yield an epoxidized long-chain diacid.

[0011] Furthermore, in the preparation of the epoxidized long-chain diacid, epichlorohydrin and tetrabutylammonium bromide are added first, and after reflux and cooling, sodium hydroxide solution is added dropwise.

[0012] Furthermore, the epoxidized long-chain diacid solution can also be made of other long-chain natural polymers containing epoxy groups.

[0013] Furthermore, the amino-triazole compound is one or a mixture of several of 4-amino-4H-1,2,4-triazole and 3-amino-1,2,4-triazole.

[0014] Furthermore, the metal ion is one or a mixture of several of Fe3+, Zn2+, Co2+, Cu2+, Ca2+, Mg2+, and Al3+.

[0015] Furthermore, in the preparation of the lignin prepolymer and the sebacic acid prepolymer, the molar ratio of the amino-triazole compound to the epoxidized lignin and the epoxidized epoxidized lignin is 1:1-5:1.

[0016] The present invention has the following beneficial effects: This invention utilizes lignin and long-chain diacids as raw materials to prepare lignin-based self-healing materials based on dynamic coordination crosslinking. The benzene ring structure of lignin endows the composite film with high strength and rigidity; the macromolecular structure of phenylpropane imparts good water stability and hydrophobicity; and the abundant hydroxyl content endows the composite film with excellent antioxidant, antibacterial, and UV protection properties. As a long-chain aliphatic diacid, it can improve the toughness of the composite film.

[0017] This invention utilizes metal ion-triazole coordination bonds as the non-covalent interaction between amino-triazole-modified epoxidized lignin prepolymers and amino-triazole-modified epoxidized sebacic acid prepolymers. The introduction of these metal ion-triazole coordination bonds enables the composite material to undergo self-healing under relatively mild conditions. Furthermore, the chemical inertness, antioxidant, reducing, and hydrolytic properties of triazoles result in high aromatic stability and resistance to degradation, effectively extending the material's service life. Implementation

[0018] The present invention will now be described in detail with reference to various embodiments. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent changes or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the protection scope of the present invention.

[0019] The preparation method of the lignin-based self-healing material based on dynamic coordination crosslinking in this invention includes the following steps: (1) preparation of amino-triazole compound (TA) modified epoxidized lignin prepolymer (T-HL); (2) preparation of TA modified epoxidized long-chain diacid prepolymer (T-HCA); (3) preparation of metal ion coordinated crosslinked T-HL / T-HCA composite material. A lignin-based self-healing material based on dynamic coordination crosslinking is obtained.

[0020] The preparation method of this invention includes the following specific steps:

[0021] A suitable amount of lignin is dissolved in a specified solvent and stirred at room temperature until completely dissolved to obtain a lignin solution with a mass fraction of 1.0%-30.0%. Then, epichlorohydrin with a molar ratio of 1:1-5:1 to the hydroxyl groups on the lignin and tetrabutylammonium bromide with a mass ratio of 1:10-1:5 to the lignin are added. The mixture is stirred under reflux at 50-100℃ for 1-6 h and cooled to room temperature. Tetrabutylammonium bromide with a mass ratio of 1:10-1:5 to the lignin and sodium hydroxide with a mass ratio of 1:1-1:5 to the lignin are simultaneously dissolved in water to obtain an aqueous solution containing 1.0%-5.0% tetrabutylammonium bromide and 1.0%-50.0% sodium hydroxide. This aqueous solution is added dropwise to the mixed solution and stirred at 100-1000 r / m for 5-12 h. After precipitation and washing multiple times in deionized water, the solution is vacuum dried for 12-36 h to obtain epoxidized lignin.

[0022] In this embodiment, the lignin can be selected from one or a mixture of several of sulfate lignin, alkali lignin, lignin sulfonate, hydrolyzed lignin and organic solvent lignin.

[0023] An appropriate amount of epoxidized lignin was dissolved in a designated solvent and stirred at room temperature until completely dissolved to obtain an epoxidized lignin solution with a mass fraction of 1.0%-20.0%. The solution temperature was lowered to approximately 0°C using an ice-water bath. A TA solution with a molar ratio of 1:1-5:1 to the epoxy groups on the epoxidized lignin was dissolved in a designated solvent to obtain a TA solution with a mass fraction of 10.0%-50.0%. This TA solution was slowly added to the epoxidized lignin solution, and the mixture was stirred for 1-6 h. The reaction was then continued at room temperature for 8-20 h until the reaction was terminated. After precipitation and washing multiple times in deionized water, the product was vacuum dried for 12-36 h to obtain T-HL. The specific reaction formula for this step is as follows:

[0024] (2) Preparation of amino-triazole modified epoxidized long-chain diacid prepolymer (hereinafter referred to as T-HCA) Dissolve an appropriate amount of long-chain diacid in a specified solvent and stir at room temperature until completely dissolved to obtain a long-chain diacid solution with a mass fraction of 1.0%-30.0%. Then add epichlorohydrin in a molar ratio of 1:1-5:1 to the carboxyl groups on the long-chain diacid and tetrabutylammonium bromide in a mass ratio of 1:20-1:10 to the long-chain diacid. Stir under reflux at 50-130℃ for 1-6 h and cool to 10-80℃. Dissolve sodium hydroxide in water in a mass ratio of 1:1-1:5 to the long-chain diacid to obtain a sodium hydroxide solution with a mass fraction of 1.0%-50.0%. Add the sodium hydroxide solution dropwise to the mixed solution and stir at 100-1000 r / m for 5-12 h. After washing several times with distilled water, dry under vacuum for 12-36 h to obtain epoxidized long-chain diacid.

[0025] In this embodiment, the long-chain diacid is one or a mixture of several of sebacic acid, octanoic acid, pimelic acid, and adipic acid. In this embodiment, the epoxidized long-chain diacid prepolymer can also be directly replaced by long-chain natural polymers rich in epoxy groups, such as epoxidized soybean oil.

[0026] An epoxidized long-chain diacid was dissolved in a specified solvent and stirred at room temperature until completely dissolved to obtain an epoxidized long-chain diacid solution with a mass fraction of 5.0%-20.0%. The solution temperature was lowered to approximately 0°C using an ice-water bath. A TA solution with a molar ratio of 1:1 to 5:1 to the epoxy groups on the epoxidized long-chain diacid was dissolved in a specified solvent to obtain a TA solution with a mass fraction of 10.0%-50.0%. This TA solution was slowly added to the epoxidized long-chain diacid solution, and the mixture was stirred for 1-6 h. The reaction was then continued at room temperature for 8-20 h until the reaction was terminated. After precipitation and washing multiple times in deionized water, the product was vacuum dried for 12-36 h to obtain T-HCA. The specific reaction is as follows:

[0027] In steps (1) and (2) above, the amino-triazole compound is one or a mixture of several of 4-amino-4H-1,2,4-triazole and 3-amino-1,2,4-triazole.

[0028] (3) Preparation of metal ion coordination crosslinked T-HL / T-HCA composite material.

[0029] T-HL and T-HCA were dissolved in a specified solvent at a molar ratio of 1:1-1:5 and stirred at room temperature until completely dissolved to obtain a solution containing 1.0%-30.0% T-HL and 5.0%-50.0% T-HCA by mass. Metal ions with a molar ratio of 1:1-1:5 to the triazole in the solution were dissolved in methanol to obtain a metal ion solution with a mass fraction of 10.0%-50.0%. This solution was slowly added dropwise to the above solution, and stirring was continued for 12-48 h. The mixture was then poured into a mold and allowed to evaporate at room temperature for 12-48 h, followed by vacuum drying at 20-80℃ for 12-48 h to obtain a lignin-based composite material with metal ion coordination crosslinking. The specific reaction formula is as follows:

[0030] In this embodiment, the metal ions are one or a mixture of several of Fe3+, Zn2+, Co2+, Cu2+, Ca2+, Mg2+, and Al3+.

[0031] In steps (1), (2), and (3) above, the specified solvent is one or a mixture of several of N,N-dimethylformamide, dimethyl sulfoxide, dioxane, and tetrahydrofuran.

[0032] In step (3) of the preparation of T-HL / T-HCA, the mold material is one or more of the following: polytetrafluoroethylene, glass, tinplate, steel, etc.

[0033] The composite material obtained by this invention possesses excellent self-healing and mechanical properties. The coordination crosslinking of TA and metal ions primarily serves a self-healing function, and the mechanical properties of the material can be controlled according to the type of metal ions and the ratio of rigid T-HL to flexible T-HCA. The method of this invention is easy to implement under experimental conditions, has low production costs, and can be widely applied to engineering materials such as coatings and films.

[0034] In this invention, the complex molecular structure of lignin is utilized. However, lignin contains active groups such as hydroxyl and carboxyl groups, which can participate in a variety of chemical reactions. In addition, the benzene ring and polycyclic ring structures in lignin endow it with high rigidity and thermal stability. It can be modified to prepare various products with excellent performance, which has extremely high application value in production.

[0035] Secondly, triazole heterocyclic compounds are also a class of heterocyclic compounds with broad biological activities, and they have wide applications in synthesis, catalysis, medicine, pesticides, life sciences, functional materials and molecular biology.

[0036] Finally, the bond energy of metal coordination bonds is higher than that of most hydrogen bonds, but lower than that of traditional covalent bonds. Common ligands include catechol, pyridine, triazole, and carboxylic acids, while metal ions include Fe2+, Zn2+, Cu2+, Ca2+, Mg2+, and Al3+. By changing the type and number of ligands and metals, materials with different mechanical properties and repair capabilities can be obtained. Furthermore, lignin-based self-healing materials based on dynamic coordination crosslinking are prepared using renewable and inexpensive lignin as a raw material. Using epoxidized lignin with a rigid structure and epoxidized long-chain diacid with a flexible structure as the matrix, a lignin-based self-healing material based on dynamic coordination crosslinking is prepared through the coordination crosslinking of triazole and metal ions.

[0037] The invention will be further illustrated below with reference to specific preparation examples: Example

[0038] (1) Preparation of 4-amino-4H-1,2,4-triazole (TA) modified epoxide lignin prepolymer (T-HL) 4 g of alkali lignin was dissolved in N,N-dimethylformamide (DMF) and stirred at room temperature until completely dissolved to obtain a lignin solution with a mass fraction of 20.0%. Then epichlorohydrin with a molar ratio of 3:1 to the hydroxyl groups on the lignin and tetrabutylammonium bromide with a mass ratio of 1:10 to the lignin were added. The mixture was stirred under reflux at 60 °C for 3 h and then cooled to room temperature.

[0039] Tetrabutylammonium bromide (3:20 by mass) and sodium hydroxide (1:4 by mass) were simultaneously dissolved in water to obtain an aqueous solution containing 1.2% tetrabutylammonium bromide and 2.0% sodium hydroxide by mass. This solution was added dropwise to the mixed solution and stirred at 500 r / m for 8 h. After settling and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain epoxidized lignin.

[0040] 2 g of epoxidized lignin was dissolved in DMF and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) epoxidized lignin solution. The solution temperature was lowered to approximately 0°C using an ice-water bath. TA (at a molar ratio of 3:1 to the epoxy groups on the epoxidized lignin) was dissolved in a specified solvent to obtain a 30.0% (w / w) TA solution. This TA solution was slowly added to the epoxidized lignin solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HL.

[0041] (2) Preparation of TA-modified epoxidized sebacic acid prepolymer (T-HGA) 4 g of sebacic acid was dissolved in DMF and stirred at room temperature until completely dissolved to obtain a 20.0% sebacic acid solution. Then, epichlorohydrin (3:1 molar ratio to the carboxyl groups of sebacic acid) and tetrabutylammonium bromide (1:20 mass ratio to sebacic acid) were added. The mixture was stirred under reflux at 117°C for 3 h and then cooled to 50°C. Sodium hydroxide (1:1 mass ratio to sebacic acid) was dissolved in water to obtain a 30.0% sodium hydroxide solution, which was added dropwise to the mixed solution. The mixture was stirred at 500 r / m for 8 h, washed several times with distilled water, and then vacuum dried for 24 h to obtain epoxidized sebacic acid.

[0042] 2 g of epoxidized sebacic acid was dissolved in DMF and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) epoxidized sebacic acid solution. The solution temperature was lowered to approximately 0°C using an ice-water bath. A TA solution with a molar ratio of 3:1 to the epoxy groups on the epoxidized sebacic acid was dissolved in a specified solvent to obtain a 30.0% (w / w) TA solution. This TA solution was slowly added to the epoxidized sebacic acid solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HGA.

[0043] (3) Preparation of Fe3+ coordinated crosslinked T-HL / T-HGA composite material.

[0044] 1 g of T-HL and 3 g of T-HGA were dissolved in DMF and stirred at room temperature until completely dissolved to obtain a solution containing 10.0% T-HL and 30.0% T-HGA by mass. Fe3+ with a molar ratio of 1:3 to triazole in the solution was dissolved in methanol to obtain a Fe3+ solution with a mass fraction of 30.0%. This Fe3+ solution was slowly added dropwise to the above solution, and stirring was continued for 24 h. The solution was then poured into a polytetrafluoroethylene mold, allowed to evaporate at room temperature for 24 h, and then dried under vacuum at 60 °C for 24 h to obtain the composite material.

[0045] Example 2: (1) Preparation of 3-amino-1,2,4-triazole (TA) modified epoxide sulfate lignin prepolymer (T-HL) 4 g of sulfate lignin was dissolved in dimethyl sulfoxide (DMSO) and stirred at room temperature until completely dissolved to obtain a lignin solution with a mass fraction of 20.0%. Epichlorohydrin (3:1 molar ratio to the hydroxyl groups on the lignin) and tetrabutylammonium bromide (1:10 mass ratio to the lignin) were then added. The mixture was stirred under reflux at 60 °C for 3 h and cooled to room temperature. Tetrabutylammonium bromide (3:20 mass ratio to the lignin) and sodium hydroxide (1:4 mass ratio to the lignin) were simultaneously dissolved in water to obtain an aqueous solution containing 1.2% tetrabutylammonium bromide and 2.0% sodium hydroxide. This aqueous solution was added dropwise to the mixed solution and stirred at 500 rpm for 8 h. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain epoxidized lignin.

[0046] 2 g of epoxidized lignin was dissolved in DMSO and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) epoxidized lignin solution. The solution temperature was lowered to approximately 0°C using an ice-water bath. A TA solution with a molar ratio of 3:1 to the epoxy groups on the epoxidized lignin was dissolved in a specified solvent to obtain a 30.0% (w / w) TA solution. This TA solution was slowly added to the epoxidized lignin solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HL.

[0047] (2) Preparation of TA-modified epoxidized octanoic acid prepolymer (T-HXA) 4 g of octanoic acid was dissolved in DMSO and stirred at room temperature until completely dissolved to obtain a 20.0% octanoic acid solution. Epichlorohydrin (3:1 molar ratio to the carboxyl groups of octanoic acid) and tetrabutylammonium bromide (1:20 molar ratio to octanoic acid) were then added. The mixture was stirred under reflux at 117°C for 3 h and then cooled to 50°C. Sodium hydroxide (1:1 molar ratio to octanoic acid) was dissolved in water to obtain a 30.0% sodium hydroxide solution, which was added dropwise to the mixed solution. The mixture was stirred at 500 r / m for 8 h, washed several times with distilled water, and then vacuum dried for 24 h to obtain epoxidized octanoic acid.

[0048] 2 g of epoxidized sebacic acid was dissolved in DMSO and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) epoxidized sebacic acid solution. The solution temperature was lowered to about 0°C using an ice-water bath. A TA solution with a molar ratio of 3:1 to the epoxy groups on the epoxidized sebacic acid was dissolved in a specified solvent to obtain a 30.0% (w / w) TA solution. This TA solution was slowly added to the epoxidized sebacic acid solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HXA.

[0049] (3) Preparation of Cu2+ coordinated crosslinked T-HL / T-HXA composite material.

[0050] 1 g of T-HL and 3 g of T-HXA were dissolved in DMSO and stirred at room temperature until completely dissolved to obtain a solution containing 10.0% T-HL and 30.0% T-HXA by mass. Cu2+ with a molar ratio of 1:3 to triazole in the solution was dissolved in methanol to obtain a Cu2+ solution with a mass fraction of 30.0%. This solution was slowly added dropwise to the above solution, and stirring was continued for 24 h. The solution was then poured into a tinplate mold, allowed to evaporate at room temperature for 24 h, and then vacuum dried at 60 °C for 24 h to obtain the composite material.

[0051] Example 3: (1) Preparation of 4-amino-4H-1,2,4-triazole (TA) modified epoxidized hydrolyzed lignin prepolymer (T-HL) 4 g of hydrolyzed lignin was dissolved in tetrahydrofuran and stirred at room temperature until completely dissolved to obtain a lignin solution with a mass fraction of 20.0%. Then, epichlorohydrin (3:1 molar ratio to the hydroxyl groups on the lignin) and tetrabutylammonium bromide (1:10 mass ratio to the lignin) were added. The mixture was stirred under reflux at 60 °C for 3 h and then cooled to room temperature. Tetrabutylammonium bromide (3:20 mass ratio to the lignin) and sodium hydroxide (1:4 mass ratio to the lignin) were simultaneously dissolved in water to obtain an aqueous solution containing 1.2% tetrabutylammonium bromide and 2.0% sodium hydroxide. This aqueous solution was added dropwise to the mixed solution, and the mixture was stirred at 500 r / m for 8 h. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain epoxidized lignin.

[0052] 2 g of epoxidized lignin was dissolved in tetrahydrofuran and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) epoxidized lignin solution. The solution temperature was lowered to approximately 0°C using an ice-water bath. A TA solution with a molar ratio of 3:1 to the epoxy groups on the epoxidized lignin was dissolved in a specified solvent to obtain a 30.0% (w / w) TA solution. This TA solution was slowly added to the epoxidized lignin solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HL.

[0053] (2) Preparation of TA-modified epoxidized hempanoic acid prepolymer (T-HPA) 4 g of pimelic acid was dissolved in tetrahydrofuran and stirred at room temperature until completely dissolved to obtain a 20.0% pimelic acid solution. Then, epichlorohydrin (3:1 molar ratio to the carboxyl groups of pimelic acid) and tetrabutylammonium bromide (1:20 mass ratio to pimelic acid) were added. The mixture was stirred under reflux at 117 °C for 3 h and then cooled to 50 °C. Sodium hydroxide (1:1 mass ratio to pimelic acid) was dissolved in water to obtain a 30.0% sodium hydroxide solution, which was added dropwise to the mixed solution. The mixture was stirred at 500 r / m for 8 h, washed several times with distilled water, and then vacuum dried for 24 h to obtain epoxidized pimelic acid.

[0054] 2 g of pimecrolic acid epoxidation was dissolved in tetrahydrofuran and stirred at room temperature until completely dissolved to obtain a 20.0% pimecrolic acid epoxidation solution. The solution temperature was lowered to about 0°C using an ice-water bath. A TA solution with a molar ratio of 3:1 to the epoxy groups on the pimecrolic acid epoxidation was dissolved in a specified solvent to obtain a 30.0% TA solution. This TA solution was slowly added to the pimecrolic acid epoxidation solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HPA.

[0055] (3) Preparation of Zn2+ coordination crosslinked T-HL / T-HPA composite material.

[0056] 1 g of T-HL and 3 g of T-HPA were dissolved in tetrahydrofuran and stirred at room temperature until completely dissolved to obtain a solution containing 10.0% T-HL and 30.0% T-HPA by mass. Zn2+ with a molar ratio of 1:3 to triazole in the solution was dissolved in methanol to obtain a Zn2+ solution with a mass fraction of 30.0%. This Zn2+ solution was slowly added dropwise to the above solution, and stirring was continued for 24 h. The solution was then poured into a glass mold, allowed to evaporate at room temperature for 24 h, and then dried under vacuum at 60 °C for 24 h to obtain the composite material.

[0057] Example 4: (1) Preparation of 3-amino-1,2,4-triazole (TA) modified epoxidized organic solvent lignin prepolymer (T-HL) 4 g of lignin was dissolved in DMF and stirred at room temperature until completely dissolved to obtain a lignin solution with a mass fraction of 20.0%. Epichlorohydrin (3:1 molar ratio to the hydroxyl groups on the lignin) and tetrabutylammonium bromide (1:10 mass ratio to the lignin) were then added. The mixture was stirred under reflux at 60 °C for 3 h and cooled to room temperature. Tetrabutylammonium bromide (3:20 mass ratio to the lignin) and sodium hydroxide (1:4 mass ratio to the lignin) were simultaneously dissolved in water to obtain an aqueous solution containing 1.2% tetrabutylammonium bromide and 2.0% sodium hydroxide. This aqueous solution was added dropwise to the mixed solution and stirred at 500 r / m for 8 h. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain epoxidized lignin.

[0058] 2 g of epoxidized lignin was dissolved in DMF and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) epoxidized lignin solution. The solution temperature was lowered to approximately 0°C using an ice-water bath. TA (at a molar ratio of 3:1 to the epoxy groups on the epoxidized lignin) was dissolved in a specified solvent to obtain a 30.0% (w / w) TA solution. This TA solution was slowly added to the epoxidized lignin solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HL.

[0059] (2) Preparation of TA-modified epoxidized adipic acid prepolymer (T-HAA) 4 g of adipic acid was dissolved in DMF and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) adipic acid solution. Epichlorohydrin (3:1 molar ratio to the carboxyl groups of adipic acid) and tetrabutylammonium bromide (1:20 (w / w)) were then added. The mixture was stirred under reflux at 117 °C for 3 h and cooled to 50 °C. Sodium hydroxide (1:1 (w / w)) was dissolved in water to obtain a 30.0% (w / w) sodium hydroxide solution, which was added dropwise to the mixed solution. The mixture was stirred at 500 r / m for 8 h, washed several times with distilled water, and then vacuum dried for 24 h to obtain epoxidized adipic acid.

[0060] 2 g of epoxidized adipic acid was dissolved in DMF and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) epoxidized adipic acid solution. The solution temperature was lowered to approximately 0°C using an ice-water bath. A TA solution with a molar ratio of 3:1 to the epoxy groups on the epoxidized adipic acid was dissolved in a specified solvent to obtain a 30.0% (w / w) TA solution. This TA solution was slowly added to the epoxidized adipic acid solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HAA.

[0061] (3) Preparation of Co2+ coordinated crosslinked T-HL / T-HAA composite material.

[0062] 1 g of T-HL and 3 g of T-HAA were dissolved in DMF and stirred at room temperature until completely dissolved to obtain a solution containing 10.0% T-HL and 30.0% T-HAA by mass. Co2+ with a molar ratio of 1:3 to the triazole in the solution was dissolved in methanol to obtain a Co2+ solution with a mass fraction of 30.0%. This Co2+ solution was slowly added dropwise to the above solution, and stirring was continued for 24 h. The solution was then poured into a polytetrafluoroethylene mold, allowed to evaporate at room temperature for 24 h, and then dried under vacuum at 60 °C for 24 h to obtain the composite material.

[0063] Example 5: (1) Preparation of 3-amino-1,2,4-triazole (TA) modified epoxidized lignin sulfonate prepolymer (T-HL) 4 g of lignin sulfonate was dissolved in DMSO and stirred at room temperature until completely dissolved to obtain a lignin solution with a mass fraction of 20.0%. Epichlorohydrin (3:1 molar ratio to the hydroxyl groups on the lignin) and tetrabutylammonium bromide (1:10 mass ratio to the lignin) were then added. The mixture was stirred under reflux at 60 °C for 3 h and cooled to room temperature. Tetrabutylammonium bromide (3:20 mass ratio to the lignin) and sodium hydroxide (1:4 mass ratio to the lignin) were simultaneously dissolved in water to obtain an aqueous solution containing 1.2% tetrabutylammonium bromide and 2.0% sodium hydroxide. This aqueous solution was added dropwise to the mixed solution and stirred at 500 r / m for 8 h. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain epoxidized lignin.

[0064] 2 g of epoxidized lignin was dissolved in DMSO and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) epoxidized lignin solution. The solution temperature was lowered to approximately 0°C using an ice-water bath. A TA solution with a molar ratio of 3:1 to the epoxy groups on the epoxidized lignin was dissolved in a specified solvent to obtain a 30.0% (w / w) TA solution. This TA solution was slowly added to the epoxidized lignin solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HL.

[0065] (2) Preparation of TA-modified epoxidized sebacic acid prepolymer (T-HSA) 4 g of sebacic acid was dissolved in DMSO and stirred at room temperature until completely dissolved to obtain a 20.0% sebacic acid solution. Then, epichlorohydrin (3:1 molar ratio to the carboxyl groups of sebacic acid) and tetrabutylammonium bromide (1:20 mass ratio to sebacic acid) were added. The mixture was stirred under reflux at 117°C for 3 h and then cooled to 50°C. Sodium hydroxide (1:1 mass ratio to sebacic acid) was dissolved in water to obtain a 30.0% sodium hydroxide solution, which was added dropwise to the mixed solution. The mixture was stirred at 500 r / m for 8 h, washed several times with distilled water, and then vacuum dried for 24 h to obtain epoxidized sebacic acid.

[0066] 2 g of epoxidized sebacic acid was dissolved in DMSO and stirred at room temperature until completely dissolved to obtain a 20.0% (w / w) epoxidized sebacic acid solution. The solution temperature was lowered to approximately 0°C using an ice-water bath. A TA solution with a molar ratio of 3:1 to the epoxy groups on the epoxidized sebacic acid was dissolved in a specified solvent to obtain a 30.0% (w / w) TA solution. This TA solution was slowly added to the epoxidized sebacic acid solution, stirred for 3 h, and then the reaction was continued at room temperature for 12 h before the reaction was terminated. After precipitation and washing multiple times in deionized water, the solution was vacuum dried for 24 h to obtain T-HSA.

[0067] (3) Preparation of Fe3+ coordinated crosslinked T-HL / T-HSA composite material.

[0068] 1 g of T-HL and 3 g of T-HSA were dissolved in DMSO and stirred at room temperature until completely dissolved to obtain a solution containing 10.0% T-HL and 30.0% T-HSA by mass. Fe3+ with a molar ratio of 1:3 to triazole in the solution was dissolved in methanol to obtain a Fe3+ solution with a mass fraction of 30.0%. This Fe3+ solution was slowly added dropwise to the above solution, and stirring was continued for 24 h. The solution was then poured into a tinplate mold, allowed to evaporate at room temperature for 24 h, and then vacuum dried at 60 °C for 24 h to obtain the composite material.

[0069] The self-healing performance of the composite materials prepared in Examples 1-5 was tested, and the specific steps are as follows: The self-healing efficiency of the material was evaluated using a tensile test method: The composite materials prepared in Examples 1-5 were used to prepare test strips with a length of 40 mm * width of 20 mm * height of 2 mm. The strips were cut at the middle along a direction perpendicular to the tensile axis. A force of 5 N was applied above the strips at a certain temperature, causing the cut strips to come into close contact. Self-healing was achieved after 5 hours of contact. The tensile rate was 200 mm / min. The self-healing efficiency can be expressed by the following formula: (T) = (healed) / (initial), where (healed) and (initial) are the tensile strengths before and after healing, respectively. The experimental results are shown in Appendix Table 1.

[0070]

[0071] As can be seen from the data in Table 1, the self-healing elastomer prepared in the examples has high tensile strength, and even after self-healing, it still possesses high mechanical strength and high self-healing efficiency (up to 67.9%). In summary, the preparation method of this invention can produce composite materials with good mechanical properties, high self-healing efficiency, and multiple reusability.

[0072] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0073] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing lignin-based self-healing materials based on dynamic coordination crosslinking, characterized in that, Includes the following steps, Preparation of amino-triazole modified epoxidized lignin prepolymers: Epoxidized lignin was dissolved in a specified solvent and stirred at room temperature until completely dissolved to obtain an epoxidized lignin solution. The solution temperature was lowered to 0°C using an ice-water bath. 4-amino-4H-1,2,4-triazole and / or 3-amino-1,2,4-triazole in a molar ratio of 1:1 to 5:1 with the epoxy groups on the epoxidized lignin were dissolved in a specified solvent to obtain a TA solution with a mass fraction of 10.0% to 50.0%. This TA solution was slowly added to the epoxidized lignin solution, stirred, and then the temperature was raised to room temperature to continue the reaction until the reaction was completed. After precipitation and washing multiple times in deionized water, the prepolymer of epoxidized lignin modified with amino-triazole compounds was obtained by vacuum drying. Preparation of amino-triazole modified epoxidized long-chain diacid prepolymers: Epoxidized long-chain diacid was dissolved in a specified solvent and stirred at room temperature until completely dissolved to obtain an epoxidized long-chain diacid solution. The solution temperature was lowered to 0℃ using an ice-water bath. 4-amino-4H-1,2,4-triazole and / or 3-amino-1,2,4-triazole with a molar ratio of 1:1 to 5:1 to the epoxy groups on the epoxidized long-chain diacid was dissolved in a specified solvent to obtain a TA solution with a mass fraction of 10.0% to 50.0%. This TA solution was slowly added to the epoxidized long-chain diacid solution and stirred for 1-6 h. The reaction was then continued at room temperature for 8-20 h until the reaction was terminated. After precipitation and washing multiple times in deionized water, the product was vacuum dried for 12-36 h to obtain an amino-triazole compound-modified epoxidized long-chain diacid prepolymer. Preparation of lignin-based self-healing materials: The amino-triazole compound modified epoxidized lignin prepolymer and the amino-triazole compound modified epoxidized long-chain diacid prepolymer are dissolved in a specified solvent at a set molar ratio. Then, a solution containing metal ions is added to carry out a coordination crosslinking reaction to obtain a coordination crosslinking reaction solution. The coordination crosslinking reaction solution is introduced into a mold, evaporated at room temperature, and then dried to obtain a metal ion coordination crosslinked lignin-based self-healing material. The metal ions are selected from Fe³⁺, Zn²⁺, Co²⁺ and / or Cu²⁺.

2. The method for preparing lignin-based self-healing materials based on dynamic coordination crosslinking according to claim 1, characterized in that, It also includes the preparation of epoxidized lignin, the specific steps of which are as follows: In the presence of tetrabutylammonium bromide solution and sodium hydroxide as catalysts, epoxide propane reacts with lignin solution under reflux to yield epoxide lignin.

3. The preparation method of lignin-based self-healing material based on dynamic coordination crosslinking according to claim 2, characterized in that, In the preparation of the epoxidized lignin, tetrabutylammonium bromide is added in two parts. The first part is added together with epichlorohydrin and stirred under reflux. The second part is the remaining tetrabutylammonium bromide and sodium hydroxide dissolved in water and added dropwise to the reflux liquid.

4. The method for preparing lignin-based self-healing materials based on dynamic coordination crosslinking according to claim 3, characterized in that, In the first and second additions, the mass ratio of the tetrabutylammonium bromide to lignin is 1:10-1:

5.

5. The method for preparing lignin-based self-healing materials based on dynamic coordination crosslinking according to claim 1, characterized in that, It also includes the preparation of epoxidized long-chain dicarboxylic acids, the specific steps of which are as follows: In the presence of tetrabutylammonium bromide solution and sodium hydroxide as catalysts, propane epoxide reacts with a long-chain diacid solution to yield an epoxidized long-chain diacid.

6. The method for preparing lignin-based self-healing materials based on dynamic coordination crosslinking according to claim 5, characterized in that, In the preparation of the epoxidized long-chain diacid, epichlorohydrin and tetrabutylammonium bromide are added first, and after reflux and cooling, sodium hydroxide solution is added dropwise.

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