A self-healing elastomer based on triple hydrogen bonds and metal coordination and its preparation method

Abstract

The present invention relates to a self-healing elastomer based on triple hydrogen bonds and metal coordination and a preparation method thereof, and a novel benzene-1,3,5-tricarboxamide (BTA) assembly unit is introduced to prepare the self-healing elastomer. BTA can form a one-dimensional fiber structure similar to the hard segment of polystyrene through triple hydrogen bond assembly, and its triple hydrogen bond interaction can be used as a reversible sacrificial bond. The BTA assembly is used as both the hard segment of microphase separation and the reversible sacrificial bond for absorbing fracture energy to regulate the mechanical properties and repair properties of the material. At the same time, the introduction of metal coordination accelerates the repair behavior of the material. The method includes synthesizing an imidazole-functionalized BTA molecule and an imidazole-functionalized acrylate polymer, and then performing coordination crosslinking on them with a metal salt to obtain a self-healing polymer elastomer material. The obtained self-healing elastomer material has good mechanical properties and excellent repair effects.

Description

Technical Field

[0001] The present invention belongs to the field of self - healing polymer materials, and relates to a self - healing elastomer based on triple hydrogen bonds and metal coordination and a preparation method thereof, specifically to the preparation of a self - healing elastomer material based on microphase separation and dual reversible non - covalent bond interactions. Background Art

[0002] Polymer materials are widely used in all walks of life and are developing towards the integration of structure - function, intelligence, and high performance. However, the damage and destruction generated during the processing and use of materials will significantly reduce their service life, and at the same time trigger a series of safety and environmental problems caused by material failure. Therefore, the design and development of materials with damage - sensing self - healing functions are of great value for extending the material life, improving the use safety, reducing the maintenance cost, and realizing recycling. Currently, self - healing materials are divided into two systems: externally - assisted self - healing and intrinsically self - healing. Externally - assisted self - healing materials are limited in application to a certain extent due to reasons such as limited repair agent content and number of repairs, and the difficulty in adjusting the matching between the repair process and the resin matrix properties.

[0003] In recent years, researchers have introduced reversible dynamic bonds into the structure to design and prepare a series of intrinsically self - healing functional materials. However, the currently developed self - healing materials generally need to be repaired under heating conditions and have a long repair time; in addition, the strength of the materials is generally low. In order to simultaneously enhance and toughen the material, it is usually required that the material has a suitable cross - linked structure and a continuous energy absorption - dissipation mechanism. The room - temperature self - healing function of materials is often achieved by introducing reversible non - covalent bonds with low bond energy into the polymer structure. Research shows that microphase separation and reversible sacrificial bonds are effective ways to coordinately improve the strength, toughness, and repair performance of elastomers. Summary of the Invention

[0004] Technical Problems to be Solved

[0005] In order to avoid the deficiencies of the prior art, the present invention proposes a self - healing elastomer based on triple hydrogen bonds and metal coordination and a preparation method thereof. In order to simultaneously improve the strength, toughness, and repair performance of the material, the present invention for the first time uses a novel benzene - 1,3,5 - tricarboxamide (BTA) assembly unit to construct microphase separation and dual reversible sacrificial bonds, thereby regulating the mechanical properties and self - healing properties, and realizing the preparation of a high - strength, high - toughness, and fast - self - healing elastomer material.

[0006] Technical Solutions

[0007] A self-healing elastomer based on triple hydrogen bonds and metal coordination, characterized by comprising imidazole-functionalized trimesic acid amide, an acrylate polymer containing imidazole functional groups, and a metal salt; the trimesic acid amide BTA in the imidazole-functionalized trimesic acid amide assembles a one-dimensional fiber structure through triple hydrogen bonds, and its triple hydrogen bonds serve as reversible sacrificial bonds to obtain a self-healing polymer elastomer material through metal coordination crosslinking; the tensile strength of the self-healing elastomer is up to 10 MPa at most, the elongation at break is 2000%, and damage repair is achieved by placing it at room temperature or below 100 °C for 12 h.

[0008] The mass ratio of the imidazole-functionalized trimesic acid amide to the acrylate polymer containing imidazole functional groups is 20:80 to 50:50; the molar ratio of the metal salt to the imidazole functional group is 1:4 to 1:7.

[0009] The imidazole-functionalized trimesic acid amide is obtained by reacting trimesoyl chloride with an aminoimidazole compound, and the structural general formula is:

[0010]

[0011] Wherein: R1 and R2 are straight-chain alkanes with benzene ring or alkyl substituents.

[0012] The aminoimidazole compound is any one or a mixture of 2-(2-methyl-1H-imidazol-1-yl)ethylamine, 1-(3-aminopropyl)imidazole, 2-(1H-imidazol-1-yl)ethylamine, 4-(2-methyl-1H-imidazole)benzylamine, 1H-imidazole-2-methylamine, and the structural formula is:

[0013]

[0014] The acrylate polymer containing imidazole functional groups is obtained by free radical copolymerization of acrylate monomers and double bond monomers containing imidazole, and the molar content of the double bond monomers containing imidazole in the polymer is 10 - 40%.

[0015] The double bond monomers containing imidazole are any one or a mixture of 4-(3-imidazol-1-ylpropionic acid)-1-butylene glycol acrylate, imidazole ethyl methacrylate, 3-(3-imidazol-1-ylpropionic acid)-1-propylene glycol acrylate, vinyl imidazole, and the chemical structure:

[0016]

[0017] The acrylate monomers are any one or a mixture of ethyl acrylate, methyl acrylate, n-octyl acrylate, n-butyl acrylate, tert-butyl acrylate.

[0018] The metal salt is any one of 4-fluorophenylmagnesium chloride, 1,3-dioxolan-2-ylethylmagnesium bromide, zinc bis(trifluoromethanesulfonyl)imide, zinc 2-mercaptobenzothiazole, zinc trifluoromethanesulfonate, zinc acetate, and iron(III) chloride.

[0019] A method for preparing a self-healing elastomer based on triple hydrogen bonds and metal coordination, characterized by the following steps:

[0020] Step 1: Mix the imidazole-functionalized benzene-1,3,5-tricarboxamide solution A and the acrylate polymer solution B containing imidazole functional groups to obtain a mixed solution;

[0021] Step 2: Gradually add dropwise the methanol solution containing the metal salt to the mixed solution under stirring;

[0022] Step 3: After the dropping is completed, place the solution in a drying oven to volatilize the solvent until the film material reaches a constant weight, obtaining a self-healing elastomer based on triple hydrogen bonds and metal coordination.

[0023] The solvents of the solution A and the solution B are one or a mixture of N,N-dimethylformamide, tetrahydrofuran, methanol, and acetonitrile.

[0024] Beneficial effects

[0025] A self-healing elastomer based on triple hydrogen bonds and metal coordination and a preparation method thereof proposed by the present invention introduce a novel benzene-1,3,5-tricarboxamide (BTA) assembly motif to prepare a self-healing elastomer. BTA can assemble through triple hydrogen bonds to form a one-dimensional fiber structure similar to the hard segment of polystyrene, and its triple hydrogen bond interaction can be used as a reversible sacrificial bond. The BTA assembly is used as both the hard segment of microphase separation and the reversible sacrificial bond for absorbing fracture energy to regulate the mechanical properties and repair properties of the material. At the same time, the introduction of metal coordination accelerates the repair behavior of the material. The method includes synthesizing an imidazole-functionalized BTA molecule and an imidazole-functionalized acrylate polymer, and then coordinating and crosslinking them with a metal salt to obtain a self-healing polymer elastomer material. The obtained self-healing elastomer material has good mechanical properties and excellent repair effects.

[0026] (1) In the present invention, acrylate and acrylate containing imidazole functional groups are first used as monomers for polymerization reaction to obtain a polymer containing imidazole functional groups. Then, an imidazole-functionalized BTA small molecule is synthesized, and a polymer material is obtained by adding metal ions to form an imidazole / metal coordination crosslinking effect. In the design concept, a novel reversible dynamic motif BTA capable of assembling through triple hydrogen bonds is used in the preparation of self-healing elastomers. BTA can form an assembly similar to the hard phase of polystyrene through triple hydrogen bonds to act as the hard segment of microphase separation, achieving the enhancement of the material. The room-temperature rapidly exchangeable dynamic sacrificial bond, the imidazole / metal ion coordination, is designed in the soft segment region of the microphase separation structure, endowing the material with rapid repair ability. When the elastomer is deformed under force, the formed hard segment microdomains can act as physical crosslinking points to enhance the mechanical properties of the elastomer material, while the soft segment microdomains can dissipate energy during the stretching process through the breakage-recombination of dynamic bonds, thereby improving the toughness of the material and endowing the material with rapid repair ability. By designing the coordination crosslinking ratio, the properties of the material can be effectively regulated, and finally an elastomer material with excellent strength, toughness, and repair performance is obtained.

[0027] (2) The present invention first selects the BTA assembly containing triple reversible hydrogen bonds as the reinforcing body and dynamic reversible bond for the design of the strength, toughness, and repair performance of the material. The design concept is that the assembly of BTA is similar to the structure of the hard segment microdomains of traditional polystyrene, but it is assembled through the induction of triple hydrogen bonds, and hydrogen bonds are a kind of reversible dynamic bonds. Therefore, when the elastomer material is fractured under external force, the reversible hydrogen bonds can absorb the energy during the fracture process of the material, improving the toughness of the material. When the fractured parts of the material are spliced together, the material can spontaneously recombine to form hydrogen bonds, endowing the material with damage repair performance. Description of the Drawings

[0028] Figure 1 : The general reaction structure formula of imidazole-functionalized mellitic triamide;

[0029] Figure 2 : The chemical structure of aminoimidazole monomers;

[0030] Figure 3 : Acrylate monomer containing imidazole functional groups;

[0031] Figure 4 : High-resolution transmission electron micrograph of the multiple hydrogen bond assembly of the self-healing elastomer based on triple hydrogen bonds and metal coordination;

[0032] Figure 5 : Stress-strain curves of the self-healing elastomer based on triple hydrogen bonds and metal coordination, where the BTA content is 10%, and the coordination numbers are 4, 4.3, and 4.5 respectively;

[0033] Figure 6: Stress-strain curves of materials based on metal coordination (comparative examples), where the coordination numbers are 4, 4.3, and 4.5 respectively;

[0034] Figure 7 : Microscope images of artificial scratches on the surface of a self-healing elastomer based on triple hydrogen bonds and metal coordination after repairing for 0 h, 6 h, and 12 h at 60 °C, with a magnification of 25. Detailed implementation manners

[0035] Now, the present invention will be further described in combination with examples and drawings:

[0036] Example 1:

[0037] React 1.33 g of trimesoyl chloride with 2.30 g of 1-(3-aminopropyl)imidazole. After reacting at room temperature for 16 h, purify by column chromatography to obtain trimesic acid triamide. Dissolve it with N,N-dimethylformamide to obtain a trimesic acid triamide solution.

[0038] Under an inert gas, add 1 g of ethyl acrylate and 1.66 g of ethyl methacrylate imidazole to a round-bottom flask. At 65 °C, use N,N-dimethylformamide as the solvent and react for 5.5 h to obtain an acrylate polymer solution containing imidazole functional groups through free radical polymerization.

[0039] Mix the trimesic acid triamide solution A and the acrylate polymer solution B containing imidazole functional groups evenly at a ratio of A:B = 20:80 to obtain solution C. Take a certain amount of zinc 2-mercaptobenzothiazole and solution C, with the ratio of metal salt to imidazole functional groups in the solution being 1:4. Slowly add the methanol solution containing the metal salt dropwise to the above solution C. After the addition is complete, place the solution in an oven to evaporate the solvent until the obtained film material reaches a constant weight to obtain a self-healing elastomer material.

[0040] Example 2:

[0041] React 1.33 g of trimesoyl chloride with 2.57 g of 2-(2-methyl-1H-imidazol-1-yl)ethylamine. After reacting at room temperature for 16 h, purify by column chromatography to obtain trimesic acid triamide. Dissolve it with N,N-dimethylformamide to obtain a trimesic acid triamide solution.

[0042] Under an inert gas, add 1 g of ethyl acrylate and 1.66 g of ethyl methacrylate imidazole to a round-bottom flask. At 65 °C, use N,N-dimethylformamide as the solvent and react for 5.5 h to obtain an acrylate polymer solution containing imidazole functional groups through free radical polymerization.

[0043] Mix the trimesic acid amide solution A and the acrylate polymer solution B containing imidazole functional groups evenly at a ratio of A:B = 35:65 to obtain the mixed solution C. Take a certain amount of zinc 2-mercaptobenzothiazole and solution C, and the ratio of the metal salt to the imidazole functional groups in the solution is 1:4. Slowly add dropwise the methanol solution dissolved with the metal salt into the above solution C while stirring. After the addition is completed, place the solution in a drying oven to evaporate the solvent until the obtained film material reaches a constant weight, and a self-healing elastomer material is obtained.

[0044] Example 3:

[0045] Mix 1.33 g of trimesoyl chloride and 2.57 g of 2-(2-methyl-1H-imidazol-1-yl)ethylamine and react. After reacting at room temperature for 16 h, purify by column chromatography to obtain trimesic acid amide. Dissolve it with N,N-dimethylformamide to obtain the trimesic acid amide solution.

[0046] Under an inert gas, add 1.84 g of n-octyl acrylate and 1.66 g of ethyl imidazole acrylate to a round-bottom flask. At 65 °C, use N,N-dimethylformamide as the solvent and react for 5.5 h to obtain an acrylate polymer solution containing imidazole functional groups through free radical polymerization.

[0047] Mix the trimesic acid amide solution A and the acrylate polymer solution B containing imidazole functional groups evenly at a ratio of A:B = 30:70 to obtain solution C. Take a certain amount of zinc bis(trifluoromethanesulfonyl)imide and solution C, and the ratio of the metal salt to the imidazole functional groups in the solution is 1:4. Slowly add dropwise the methanol solution dissolved with the metal salt into the above solution C. After the addition is completed, place the solution in a drying oven to evaporate the solvent until the obtained film material reaches a constant weight, and a self-healing elastomer material is obtained.

[0048] Example 4:

[0049] Mix 1.33 g of trimesoyl chloride and 2.57 g of 2-(2-methyl-1H-imidazol-1-yl)ethylamine and react. After reacting at room temperature for 16 h, purify by column chromatography to obtain trimesic acid amide. Dissolve it with N,N-dimethylformamide to obtain the trimesic acid amide solution.

[0050] Under an inert gas, add 1.28 g of n-butyl acrylate and 2.66 g of 4-(3-imidazol-1-ylpropanoic acid)-1,4-butanediol diacrylate to a round-bottom flask. At 65 °C, use N,N-dimethylformamide as the solvent and react for 5.5 h to obtain an acrylate polymer solution containing imidazole functional groups through free radical polymerization.

[0051] Mix the trimesic acid amide solution A and the acrylate polymer solution B containing imidazole functional groups evenly at a ratio of A:B = 30:70 to obtain solution C. Take a certain amount of zinc bis(trifluoromethanesulfonyl)imide and solution C, with the ratio of metal salt to imidazole functional groups in the solution being 1:4. Slowly add dropwise the methanol solution dissolving the metal salt into the above solution C while stirring. After the addition is completed, place the solution in a drying oven to evaporate the solvent until the obtained film material reaches a constant weight, thus obtaining the self-healing elastomer material.

[0052] Example Five:

[0053] Mix 1.33 g of trimesoyl chloride and 2.30 g of 1-(3-aminopropyl)imidazole and react. After reacting for 16 h at room temperature, purify by column chromatography to obtain trimesic acid amide. Dissolve it with N,N-dimethylformamide to obtain the trimesic acid amide solution.

[0054] Under an inert gas, add 1.28 g of n-butyl acrylate and 2.66 g of 4-(3-imidazol-1-ylpropionic acid)-1-butylene glycol acrylate to a round-bottom flask. At 65 °C, use N,N-dimethylformamide as the solvent and react for 5.5 h. Obtain the acrylate polymer solution containing imidazole functional groups through radical polymerization.

[0055] Mix the trimesic acid amide solution A and the acrylate polymer solution B containing imidazole functional groups evenly at a ratio of A:B = 20:80 to obtain solution C. Take a certain amount of zinc trifluoromethanesulfonate and solution C, with the ratio of metal salt to imidazole functional groups in the solution being 1:4. Slowly add dropwise the methanol solution dissolving the metal salt into the above solution C while stirring. After the addition is completed, place the solution in a drying oven to evaporate the solvent until the obtained film material reaches a constant weight, thus obtaining the self-healing elastomer material.

[0056] Example Six:

[0057] Mix 1.33 g of trimesoyl chloride and 3.36 g of 4-(2-methyl-1H-imidazole)benzylamine and react. After reacting for 16 h at room temperature, purify by column chromatography to obtain trimesic acid amide. Dissolve it with N,N-dimethylformamide to obtain the trimesic acid amide solution.

[0058] Under an inert gas, add 1.28 g of n-butyl acrylate and 2.52 g of 3-(3-imidazol-1-ylpropionic acid)-1-propylene glycol methacrylate to a round-bottom flask. At 65 °C, use N,N-dimethylformamide as the solvent and react for 5.5 h. Obtain the acrylate polymer solution containing imidazole functional groups through radical polymerization.

[0059] The solution A of benzene-1,3,5-tricarboxamide and the solution B of an acrylate polymer containing imidazole functional groups were mixed evenly at a ratio of A:B = 50:50 to obtain solution C. A certain amount of 1,3-dioxolan-2-yl-ethylmagnesium bromide and solution C were taken, and the ratio of the metal salt to the imidazole functional groups in the solution was 1:4. The methanol solution dissolved with the metal salt was added dropwise to the above solution C drop by drop while stirring. After the addition was completed, the solution was placed in a drying oven to volatilize the solvent until the obtained film material reached a constant weight, and a self-healing elastomer material was obtained.

[0060] Comparative example:

[0061] Under an inert gas, 1.28 g of n-butyl acrylate and 2.66 g of 4-(3-imidazol-1-ylpropanoic acid)-1-butylene glycol acrylate were mixed and added to a round-bottom flask. At 65 °C, N,N-dimethylformamide was used as the solvent, and the reaction was carried out for 5.5 h. A solution of an acrylate polymer containing imidazole functional groups was obtained by radical polymerization.

[0062] A certain amount of zinc bis(trifluoromethanesulfonyl)imide and the solution B of an acrylate polymer containing imidazole functional groups were taken, and the ratios of the metal salt to the imidazole functional groups in the solution were 1:4, 1:4.3, and 1:4.5 respectively. The methanol solution dissolved with the metal salt was added dropwise to the above solution B drop by drop while stirring. After the addition was completed, the solution was placed in a drying oven to volatilize the solvent until the obtained film material reached a constant weight, and a self-healing elastomer material was obtained.

[0063] The self-healing elastomer materials obtained in the above examples and comparative examples were subjected to evaluation tests:

[0064] (1) The elastomer prepared in the example was characterized by high-resolution transmission electron microscopy, and the results were as Figure 4 shown. A large number of fibrous assemblies were formed in the material, with a diameter of about 20 nm. It can be seen that a microphase separation structure did appear in the elastomer material, which is in line with the design structure that BTA can form hard segment microdomains through hydrogen bond assembly, providing support for BTA to enhance, toughen and promote the repair of the target material from the microscopic structure aspect.

[0065] (2) The mechanical properties of the examples and comparative examples were tested using a universal tensile testing machine, and the results were as Figure 5 and Figure 6 shown. From Figure 5It can be seen that for the elastomer with BTA added, due to the microphase separation hard phase formed by the BTA assembly, when adjusting the coordination crosslinking degree, all three samples exhibit the tensile mechanical behavior of the elastomer, and the strength and elongation at break are adjustable. In the control group without BTA added, there is only the coordination crosslinking effect. When changing the crosslinking degree of the material, the material transforms between plastic and non-load-bearing soft materials and does not exhibit the behavior of an elastomer. When the coordination number of the elastomer is 4.0, the elongation at break of the comparative example is relatively low. After adding BTA, the elongation of the material increases to a certain extent, showing a certain toughness. When the coordination numbers are 4.3 and 4.5, the elongation at break of the comparative example can reach 2000%, but there is almost no strength. After adding BTA, the strength of the material increases to 4.8 MPa and 3.1 MPa respectively, and the elongation at break can reach 510% and 678% respectively. The higher the coordination crosslinking degree, the better the material strength.

[0066] The mechanical test results show that introducing the reversible dynamic unit BTA into the preparation of the elastomer, the microphase separation structure that appears in the elastomer can improve the strength of the material, and the added metal ion coordination effect can regulate the strength and toughness of the elastomer. In the material without the BTA unit, the necessary hard-soft microphase separation structure for the elastomer is not formed, so it does not have the properties of an elastomer.

[0067] (3) The surface scratch repair effect of the examples was observed by optical microscopy, and the results are as Figure 7 shown. At 60 °C, after 6 h of repair, the cross scratches in the elastomer material basically disappeared; after 12 h of repair, the scratches had disappeared.

[0068] The present invention uses the above examples to illustrate a self-healing elastomer based on triple hydrogen bonds and metal coordination and its preparation method, but the present invention is not limited to the above examples, that is, it does not mean that the present invention must rely on the above examples to be implemented. Any improvement to the present invention, the equivalent substitution of each raw material of the product of the present invention, and the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A self-healing elastomer based on triple hydrogen bonds and metal coordination, characterized in that It includes imidazole-functionalized trimesic acid amide, acrylate polymer containing imidazole functional groups, and metal salts; in the imidazole-functionalized trimesic acid amide, trimesic acid amide (BTA) assembles a one-dimensional fiber structure through triple hydrogen bonds, and its triple hydrogen bonds serve as reversible sacrificial bonds to obtain a self-healing polymer elastomer material through metal coordination cross-linking; the tensile strength of the self-healing elastomer is up to 10 MPa at most, and the elongation at break is 2000%, and damage repair is achieved after being placed at room temperature or below 100 °C for 12 h; the mass ratio of the imidazole-functionalized trimesic acid amide to the acrylate polymer containing imidazole functional groups is 20:80 to 50:50; the molar ratio of the metal salt to the imidazole functional group is 1:4 to 1:7; the imidazole-functionalized trimesic acid amide is obtained by reacting trimesoyl chloride with aminoimidazole compounds, and the structural formula of the aminoimidazole compound is:

2. The self-healing elastomer based on triple hydrogen bonds and metal coordination according to claim 1, characterized in that: The acrylate polymer containing imidazole functional groups is obtained by free radical copolymerization of acrylate monomers and double bond monomers containing imidazole, and the molar content of the double bond monomers containing imidazole in the polymer is 10-40%.

3. The self-healing elastomer based on triple hydrogen bonds and metal coordination according to claim 2, characterized in that: The double bond monomers containing imidazole are any one or a mixture of 4-(3-imidazol-1-ylpropionic acid)-1-butylene glycol acrylate, imidazole ethyl methacrylate, 3-(3-imidazol-1-ylpropionic acid)-1-propylene glycol acrylate, vinyl imidazole, etc., and the chemical structure:

4. The self-healing elastomer based on triple hydrogen bonds and metal coordination according to claim 2, characterized in that: The acrylate monomers are any one or a mixture of ethyl acrylate, methyl acrylate, n-octyl acrylate, n-butyl acrylate, tert-butyl acrylate.

5. The self-healing elastomer based on triple hydrogen bonds and metal coordination according to claim 1, wherein: The metal salts are any one of 4-fluorophenylmagnesium chloride, 1,3-dioxocyclopentyl-2-ethylmagnesium bromide, zinc bis(trifluoromethanesulfonyl)imide, zinc 2-mercaptobenzothiazole, zinc trifluoromethanesulfonate, zinc acetate, ferric chloride.

6. A method for preparing a self-healing elastomer based on triple hydrogen bonds and metal coordination according to any one of claims 1 to 5, characterized in that The steps are as follows: Step 1: Mix the imidazole-functionalized trimesic acid amide solution A and the acrylate polymer solution B containing imidazole functional groups to obtain a mixed solution; Step 2: Gradually dropwise add the methanol solution dissolved with the metal salt into the mixed solution while stirring; Step 3: After the dropping is completed, place the solution in an oven to volatilize the solvent until the film material reaches a constant weight to obtain a self-healing elastomer based on triple hydrogen bonds and metal coordination.

7. The method according to claim 6, characterized in that: The solvents of the solution A and the solution B are one or a mixture of N,N-dimethylformamide, tetrahydrofuran, methanol, and acetonitrile.

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