A self-repairing material of nucleobase pair assembly and a preparation method and application thereof

Abstract

The application provides a self-repairing material based on nucleobase pairs, and a preparation method and application thereof. The self-repairing material comprises a modified matrix material and modified graphene two-dimensional nanosheets embedded in the modified matrix material; the modified graphene two-dimensional nanosheets comprise graphene oxide modified by a modifier containing dynamic hydrogen bonds; and the modified matrix material comprises a matrix material modified by a monomer containing six-times azido and / or a nucleobase chain extender. In the self-repairing material provided by the application, the interface between the modified graphene two-dimensional nanosheets and the polyurethane matrix material is due to the existence of high-density nucleobase pair hydrogen bonds, so that the graphene two-dimensional nanosheets are arranged in the polyurethane matrix material in a parallel arrangement, have a biomimetic inverse nacre structure, and thus the mechanical strength of the self-repairing material is improved, and the self-repairing material has excellent stretchable performance.

Description

Technical Field

[0001] This invention relates to the field of self-healing coating technology, specifically to a self-healing material based on nucleobase pair assembly, its preparation method, and its application. Background Technology

[0002] Self-healing supramolecular elastomers have attracted considerable attention due to their ability to autonomously repair material damage and defects to restore their original function, recyclability, and reduced environmental burden, leading to their widespread application in fields such as artificial electronic skin, flexible robots, and wearable electronic devices. The polymer damage repair capability of supramolecular polyurethanes is typically achieved through the reversible dynamic bonds of cross-linked molecular chains or the physical structure of the polymer network, including covalent or non-covalent hydrogen bonds, imine bonds, metal-ligand coordination, disulfides, and Diels-Alder (DA) reactions. However, most of these self-healing elastomers require specific stimuli such as molecular changes, light changes, or temperature changes to achieve functional repair. Existing technologies propose introducing non-covalent hydrogen interactions into the molecular chains as reversible cross-linking bonds and sacrificial bonds to prepare tough, room-temperature self-healing materials. However, due to the inherent contradiction between the material's mechanical strength and self-healing ability caused by weak non-covalent bonds, such materials typically exhibit limited ultimate tensile strength and low elongation. Therefore, balancing the contradiction between the mechanical strength, tensile properties, and rapid room-temperature self-healing ability of self-healing materials remains a significant challenge. This is because the high mechanical properties of materials come from different molecular mechanisms in the rigid molecular structure, while the self-healing ability depends on the dynamic breakage and reconstruction of molecular chains, so they are usually mutually exclusive.

[0003] In nature, spider silk and nacre, based on non-covalent self-assembly of biomacromolecules, exhibit an extraordinary combination of contradictory mechanical properties and a certain degree of self-healing ability after damage. In spider silk, dense hydrogen-bonded motifs and polypeptide chains, forming small β-sheet nanocrystals uniformly embedded in an amorphous matrix, allow for dynamic hydrogen bond breaking and recombination under external force, dissipating a large amount of energy and making it one of the strongest materials found in nature. The unique "brick-and-mortar" structure of natural nacre, evolved over centuries, consists of 4 wt.% biopolymers and approximately 96 wt.% inorganic sheets, exhibiting extremely high strength, toughness, and stability. Loading rigid inorganic nanofillers is a primary means of enhancing the mechanical strength of polymers. While this method can efficiently enhance the mechanical properties of low-strength polymer materials, the introduction of nanofillers restricts the movement of polymer chains, limiting self-healing performance and making it difficult to achieve high tensile properties; that is, existing self-healing material systems cannot simultaneously satisfy the contradiction between high mechanical properties, tensile strength, and rapid self-healing ability. Therefore, it is of great significance to design self-healing coatings that combine high mechanical strength, excellent tensile properties, and rapid room temperature self-healing capabilities.

[0004] To address the problems existing in the prior art, this invention provides a self-healing material based on nucleobase pair assembly, its preparation method, and its application. The self-healing coating based on nucleobase pair assembly is prepared by synergistically combining main chain hydrogen bonds, side chain hydrogen bonds, and interfacial hydrogen bonds. It can achieve self-healing not only at room temperature but also at low temperature and / or in aqueous environments. Summary of the Invention

[0005] In view of this, the present invention provides a self-healing material based on nucleobase pair assembly, its preparation method and application, which successfully balances the contradictions among high mechanical properties, excellent tensile strength and rapid room temperature self-healing ability in the self-healing material system, thereby enabling its application in the field of metal corrosion protection or flexible crawling robots.

[0006] To achieve the above objectives, this invention provides a self-healing material based on nucleobase pair assembly, comprising a modified matrix material and modified graphene two-dimensional nanosheets; wherein the modified graphene two-dimensional nanosheets comprise graphene oxide modified with a modifier containing dynamic hydrogen bonds; the modified matrix material comprises a matrix material modified with a monomer containing hexa-hydrogen bonds and / or a nucleobase chain extender. Furthermore, interfacial hydrogen bonds of nucleobase pairs are formed at the interface between the modified graphene two-dimensional nanosheets and the modified matrix material, causing the modified graphene two-dimensional nanosheets to align parallel within the modified matrix material, thereby giving the self-healing material a biomimetic anti-pearl structure.

[0007] Preferably, the modifier containing dynamic hydrogen bonds and the nucleobase chain extender each contain complementary bases for forming the nucleobase pair.

[0008] Furthermore, the nucleobase pairs include, but are not limited to, any one of the following combinations: thymine and adenine (T=A), cytosine and guanine (C=G), and uracil and adenine (U=A).

[0009] Preferably, the modifier containing dynamic hydrogen bonds includes any one of the nucleobases thymine, cytosine, uracil, adenine, and guanine.

[0010] Preferably, the nucleobase chain extender is selected from at least monomers containing pyrimidines or purines.

[0011] More preferably, the pyrimidine monomer comprises any one of thymine, cytosine, and uracil.

[0012] More preferably, the purine monomers include either adenine or guanine.

[0013] Preferably, the monomer containing six hydrogen bonds includes adipicohydrazide.

[0014] Preferably, the modified matrix material contains multiple types of hydrogen bonds, including a combination of two or three of the following: main chain hydrogen bonds, side chain hydrogen bonds, and interfacial hydrogen bonds.

[0015] Preferably, the energy diffusion mechanism constructed by the breaking-movement-reconstruction of the multi-type hydrogen bonds enables the room temperature self-healing material to have self-healing function in room temperature, low temperature or water environment.

[0016] More preferably, the low temperature is -2℃ to 5℃.

[0017] Preferably, the main-chain hydrogen bonds are obtained by introducing adipic acid dihydrazide monomers containing six hydrogen bonds into the matrix material.

[0018] Preferably, the side-chain hydrogen bonds are obtained by using the nucleobase chain extender in the matrix material.

[0019] Preferably, the interfacial hydrogen bonds are formed through an interface formed by embedding the modified graphene two-dimensional nanosheets in the matrix material.

[0020] Preferably, the method for preparing the modified graphene two-dimensional nanosheets includes: adding the modifier containing dynamic hydrogen bonds to a graphene oxide dispersion activated by N,N′-carbonyldiimidazole (CDI), and stirring at 20-80°C for 4-12 hours to obtain the modified graphene two-dimensional nanosheets.

[0021] Preferably, the mass ratio of the modifier containing dynamic hydrogen bonds to graphene oxide is 1:10 to 100:1.

[0022] More preferably, the mass ratio of CDI to graphene oxide in the CDI-activated graphene oxide dispersion is 10:1 to 100:1.

[0023] Preferably, the graphene oxide dispersion is a 0.1-10 mg / mL graphene oxide / water dispersion.

[0024] Preferably, the graphene oxide has a diameter of 0.5–15 μm and a thickness of 0.7–10 nm.

[0025] Preferably, the self-healing material's repair function includes self-healing of mechanical properties and / or self-healing of salt water corrosion protection function and / or self-healing of photothermal response crawling function.

[0026] Preferably, the self-healing of the mechanical properties means that the tensile strength of the material recovers to 70% to 90%.

[0027] As another objective, the present invention also provides a method for preparing the above-mentioned self-healing material based on nucleobase pair assembly. An embodiment of the present invention also provides a method for preparing a room-temperature self-healing coating based on nucleobase pair assembly, comprising: introducing two or more combinations of main-chain hydrogen bonds, side-chain hydrogen bonds, and interfacial hydrogen bonds into a prepolymer after the reaction of a polyol and a diisocyanate to obtain a polyurethane material; then adding modified graphene two-dimensional nanosheets; and due to the presence of high-density interfacial nucleobase pair hydrogen bonds, the modified graphene two-dimensional nanosheets are arranged in parallel within the polyurethane to obtain a composite material with a biomimetic anti-pearl structure.

[0028] Specifically, it includes the following steps:

[0029] S1. Provide modified matrix materials;

[0030] One or both of the main chain hydrogen bonds and the side chain hydrogen bonds are introduced into the prepolymer of the matrix material to obtain the modified matrix material;

[0031] S2. Provides modified graphene two-dimensional nanosheets;

[0032] A modifier containing dynamic hydrogen bonds was added to a CDI-activated graphene oxide dispersion, and the modified graphene two-dimensional nanosheets were obtained after stirring and reaction.

[0033] S3. Preparation of self-healing materials;

[0034] The modified graphene two-dimensional nanosheets and the modified matrix material are mixed and stirred to obtain the self-healing material.

[0035] In a preferred embodiment, in S1, the matrix material is polyurethane; the preparation method of the modified matrix material includes blending a polyol, a diisocyanate and an organic solvent, and stirring at 60-100°C for 2-5 hours to obtain a prepolymer; adding one or a combination of adipic acid dihydrazide and a nucleobase chain extender to the prepolymer and stirring at 30-70°C for 2-20 hours to obtain a polyurethane material.

[0036] Preferably, the diisocyanate comprises one of dicyclohexylmethane diisocyanate (HMDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI).

[0037] Preferably, the polyol comprises at least one of polytetrahydrofuran (PTMEG), 1,4-butanediol (BDO), and polypropylene glycol (PPG).

[0038] Preferably, the organic solvent includes at least one of N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF).

[0039] Preferably, the mass ratio of the polyol to the organic solvent is 2:1 to 1:5.

[0040] Preferably, the molar ratio of the polyol to the diisocyanate is 1:1 to 1:2.

[0041] Preferably, the molar ratio of the polyol and one or two combinations of adipic dihydrazide and nucleobase chain extender is 1:1.

[0042] In S2, the mass ratio of the modifier containing dynamic hydrogen bonds to the graphene oxide is 1:10 to 100:1.

[0043] Preferably, in the CDI-activated graphene oxide dispersion, the mass ratio of CDI to graphene oxide is 10:1 to 100:1.

[0044] Preferably, the CDI-activated graphene oxide dispersion is a 0.1–10 mg / mL graphene oxide / water dispersion; wherein the graphene oxide has a diameter of 0.5–15 μm and a thickness of 0.7–10 nm.

[0045] Preferably, in step S3, the mass ratio of the modified matrix material to the modified graphene two-dimensional nanosheets is 2000:1 to 20:1.

[0046] Preferably, the mixing temperature is 25–50°C, and the stirring reaction time is 0.5–5 h.

[0047] As one of the objectives of the invention, the present invention also provides a self-healing coating, which is obtained by curing the above-mentioned self-healing material based on nucleobase pair assembly; preferably, the curing temperature is 40-100°C and the time is 10-60h.

[0048] Based on the above technical solutions, the self-healing material assembled from nucleobase pairs disclosed in this invention is formed through multi-type hydrogen bond connections. These multi-type hydrogen bonds are a combination of main chain hydrogen bonds, side chain hydrogen bonds, and interfacial hydrogen bonds. The nucleobase pairs are one of thymine and adenine (T=A), cytosine and guanine (C=G), or uracil and adenine (U=A). The preparation method includes: introducing a side chain containing the above-mentioned pyrimidine or purine monomers into the main chain containing adipic acid dihydrazide monomers, and finally introducing graphene two-dimensional nanosheets modified with the monomers corresponding to the above-mentioned nucleobase pairs. Due to the presence of interfacial nucleobase pair hydrogen bonds, the modified graphene two-dimensional nanosheets of this invention can achieve parallel alignment in polyurethane. The prepared room-temperature self-healing coating assembled from nucleobase pairs exhibits excellent mechanical strength, stretchability, and rapid self-healing capabilities in room temperature, low temperature, and aqueous environments due to the synergistic effect of side chain hydrogen bonds, multiple dynamic hydrogen bonds, and interfacial nucleobase pair hydrogen bonds.

[0049] The beneficial technical effects obtained by this invention are as follows:

[0050] (1) In the self-healing material provided by the technical solution of the present invention, due to the presence of high-density nuclear base pairs hydrogen bonds at the interface between the modified graphene two-dimensional nanosheets and the polyurethane matrix material, the graphene two-dimensional nanosheets are arranged in parallel in the polyurethane matrix, thereby improving the mechanical strength of the material and having excellent tensile properties; its mechanical tensile strength is 10-50 MPa and its elongation at break is 1000-1800%.

[0051] (2) The self-healing material assembled by the nucleobase pair provided by the present invention has a rapid self-healing ability in room temperature, low temperature (~2℃) and water environment due to the energy diffusion mechanism constructed by the breaking-movement-reconstruction of multiple types of hydrogen bonds in the matrix material.

[0052] (3) The room temperature self-healing material assembled by the nucleobase pair provided by the present invention can recover 60% to 90% of its ultimate tensile strength after being cut into two segments and contacted at room temperature for 0.5 to 12 hours. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the synthesis process of the polyurethane material obtained in Example 1 of the present invention;

[0054] Figure 2 This is a scanning electron microscope image of the room temperature self-healing coating composed of nucleobase pairs as described in Example 1 of the present invention, which contains parallel-arranged two-dimensional nanosheets.

[0055] Figure 3 This is the tensile stress-strain curve of the room temperature self-healing coating assembled with nucleobase pairs prepared in Example 1 of the present invention.

[0056] Figure 4This is a scanning electron microscope image of the room temperature self-healing coating assembled by nucleobase pairs prepared in Example 1 of the present invention after being cut into two segments and then contacted at room temperature for 2 hours.

[0057] Figure 5 This is the tensile stress-strain curve of the room temperature self-healing coating assembled by nucleobase pairs prepared in Example 1 of the present invention after being cut into two segments and then contacted at room temperature for 2 hours.

[0058] Figure 6 This is a local electrochemical impedance spectroscopy diagram of the self-healing behavior of the room temperature self-healing coating assembled by nucleobase pairs prepared in Example 1 of the present invention in 3.5 wt.% sodium chloride ice-salt water (~2°C);

[0059] Figure 7 This is an optical photograph of the crawling process of a crawling robot after 2 hours of room temperature repair using a room temperature self-healing coating assembled with nucleobase pairs prepared in Example 1 of this invention, under an infrared lamp. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0061] One aspect of the present invention provides a room temperature self-healing coating based on nucleobase pair-driven assembly of natural spider silk and nacre structure, which is formed by a combination of main chain hydrogen bonds, side chain hydrogen bonds and interface hydrogen bonds, wherein the modified graphene two-dimensional nanosheets and polyurethane are arranged in parallel in the polyurethane due to the presence of high density nucleobase pair hydrogen bonds at the interface.

[0062] In some preferred embodiments, the modified graphene two-dimensional nanosheets are prepared from graphene oxide modified with one of the nucleobases thymine, cytosine, uracil, adenine, and guanine.

[0063] In some preferred embodiments, the method for preparing the modified graphene two-dimensional nanosheets includes: adding a modifier containing dynamic hydrogen bonds to a graphene oxide dispersion activated by N,N′-carbonyldiimidazole (CDI), and stirring at 20-80°C for 4-12 h to obtain modified graphene two-dimensional nanosheets.

[0064] Furthermore, the modifier containing dynamic hydrogen bonds is one of the above-mentioned nucleobases thymine, cytosine, uracil, adenine, and guanine.

[0065] Furthermore, the mass ratio of the modifier to graphene oxide is 1:10 to 100:1.

[0066] Furthermore, the mass ratio of CDI to graphene oxide in the CDI-activated graphene oxide dispersion is 10:1 to 100:1.

[0067] Furthermore, the graphene oxide dispersion is a 0.1–10 mg / mL graphene oxide / water dispersion.

[0068] Furthermore, the graphene oxide has a diameter of 0.5–15 μm and a thickness of 0.7–10 nm.

[0069] Another aspect of the present invention provides a method for preparing a self-healing material, comprising: introducing two or more combinations of main chain hydrogen bonds, side chain hydrogen bonds, and interfacial hydrogen bonds into a prepolymer after the reaction of a polyol and a diisocyanate to obtain a polyurethane material.

[0070] In some preferred embodiments, the preparation method includes the following reaction conditions: blending a polyol, a diisocyanate and an organic solvent, and stirring at 60–100°C for 2–5 h to obtain a prepolymer; adding one or a combination of adipic acid dihydrazide and a nucleobase chain extender to the prepolymer and stirring at 30–70°C for 2–20 h to obtain a polyurethane material.

[0071] Furthermore, the diisocyanate comprises one of dicyclohexylmethane diisocyanate (HMDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), and hexamethylene diisocyanate (HDI).

[0072] Furthermore, the polyol comprises at least one of polytetrahydrofuran (PTMEG), 1,4-butanediol (BDO), and polypropylene glycol (PPG).

[0073] In some preferred embodiments, the organic solvent includes at least one of N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N,N-dimethylformamide (DMF).

[0074] Furthermore, the mass ratio of the polyol to the organic solvent is 2:1 to 1:5.

[0075] Furthermore, the molar ratio of the polyol to the diisocyanate is 1:1 to 1:2.

[0076] Furthermore, the molar ratio of the polyol and one or two combinations of adipic dihydrazide and nucleobase chain extender is 1:1.

[0077] Another aspect of the present invention provides a method for preparing a room temperature self-healing coating assembled from nucleobase pairs, comprising: adding modified graphene two-dimensional nanosheets to the above polyurethane solution; due to the presence of high-density nucleobase pair hydrogen bonds at the interface, the modified graphene two-dimensional nanosheets are arranged in parallel in the polyurethane to obtain a composite material with a biomimetic anti-pearl structure.

[0078] The composite coating is cured to obtain a room temperature self-healing coating of the nucleobase pair assembly.

[0079] Furthermore, the mass ratio of the polyurethane material to the modified graphene two-dimensional nanosheets is 2000:1 to 20:1.

[0080] Furthermore, the mixing temperature is 25–50°C, and the stirring time is 0.5–5 h.

[0081] In some preferred embodiments, the curing temperature is 40–100°C and the curing time is 10–60 h.

[0082] In some preferred embodiments, the room-temperature self-healing coating assembled from nucleobase pairs possesses rapid room-temperature functional self-healing capability due to the energy diffusion mechanism constructed by the breaking-movement-reconstruction of multiple types of hydrogen bonds in polyurethane.

[0083] In some more typical specific implementation examples, the preparation method of a room temperature self-healing coating of nucleobase pair assembly according to the present invention includes the following steps:

[0084] 1) Graphene two-dimensional nanosheet modification: Add a modifier containing dynamic hydrogen bonds in a mass ratio of 1:10 to 100:1 to a CDI-activated graphene oxide dispersion and stir at 20 to 80°C for 4 to 12 hours.

[0085] 2) Preparation of self-healing polyurethane material: Polyol, diisocyanate and organic solvent are blended and stirred at 60-100°C for 2-5 h to obtain a prepolymer; one or a combination of adipic acid dihydrazide and nucleobase chain extender are added to the prepolymer and stirred at 30-70°C for 2-20 h to obtain polyurethane material.

[0086] 3) Preparation of room temperature self-healing coating with nucleobase pair assembly: A polyurethane solution with a mass ratio of 2000:1 to 20:1 and modified graphene two-dimensional nanosheets are mixed and stirred at 25 to 50°C for 0.5 to 5 hours to obtain a nacre-like self-healing material. Finally, the composite material is cured to obtain a room temperature self-healing coating with nucleobase pair assembly; wherein the curing temperature is 40 to 100°C and the time is 10 to 60 hours.

[0087] This invention also provides a room-temperature self-healing coating assembled from nucleobase pairs prepared by the aforementioned method.

[0088] This invention also provides the application of the aforementioned nucleobase pair-assembled room temperature self-healing coating in the preparation of metal corrosion protection structures or flexible crawling robots.

[0089] In summary, this invention prepares a room-temperature self-healing coating assembled from nucleobase pairs by synergistically combining main-chain hydrogen bonds, side-chain hydrogen bonds, and interfacial hydrogen bonds. Specifically, modified graphene two-dimensional nanosheets are arranged in parallel within polyurethane due to the presence of high-density interfacial nucleobase pair hydrogen bonds. The room-temperature self-healing coating assembled from nucleobase pairs exhibits high mechanical strength due to the parallel-arranged nanosheets, and excellent stretchability due to the presence of multiple types of hydrogen bonds. It possesses rapid room-temperature functional self-healing capability through an energy diffusion mechanism constructed by the breakage-movement-reconstruction of multiple types of hydrogen bonds in polyurethane; specifically, the mechanical tensile strength of the room-temperature self-healing coating assembled from nucleobase pairs is 10–50 MPa, and the elongation at break is 1000–1800%; furthermore, the ultimate tensile strength of a polyurethane coating cut into two segments can recover 60%–90% after contact at room temperature for 0.5–12 hours. This successfully balances the contradictions between high mechanical properties, excellent stretchability, and rapid room-temperature self-healing capability in the self-healing material system.

[0090] It should be noted that, unless otherwise specified, all raw materials and chemical reagents used in this invention are commercially available.

[0091] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0092] Example 1

[0093] This embodiment provides a method for preparing a room temperature self-healing coating assembled from nucleobase pairs, which will be described below using polyurethane as the matrix material.

[0094] See Figure 1 The figure shows a schematic diagram of the preparation process of the self-healing material. As shown, PTMEG (polytetrahydrofuran ether diol, molecular weight 2000 g / mol), HMDI (dicyclohexylmethane diisocyanate), and other components are stirred at 80°C for 3 hours under nitrogen protection to obtain a prepolymer. Adipate dihydrazide and a thymine-containing nucleobase chain extender are added to the prepolymer to react and obtain a modified polyurethane material. The modified polyurethane material is then mixed with modified graphene to obtain a self-healing material with nucleobase pair assembly.

[0095] Specifically, the preparation method includes the following steps:

[0096] 1. Modification of graphene two-dimensional nanosheets: Adenine modifier containing dynamic hydrogen bonds with a mass ratio of 1.2:1 was added to a 2 mg / mL CDI (N,N′-carbonyldiimidazole) activated graphene oxide dispersion and stirred at 60 °C for 8 h, wherein the mass ratio of CDI to graphene oxide was 27:1.

[0097] The preparation method of CDI-activated graphene oxide includes: dispersing 1.6 g of graphene nanosheets (GO nanosheets) in 800 mL of DMF and ultrasonically dispersing in a water bath for 20 minutes. Then, adding 43.24 g of N,N′-carbonyldiimidazole (CDI) and stirring at 60 °C for 12 h. The resulting suspension is centrifuged at 10,000 rpm for 10 minutes and washed three times with ethanol, deionized water, and DMF, respectively, to obtain CDI-activated graphene oxide. The surface of the obtained CDI-activated graphene oxide contains a large number of oxygen-containing functional groups (such as carboxyl-COOH groups) to facilitate the subsequent grafting of adenine modifiers containing dynamic hydrogen bonds.

[0098] 2. Preparation of self-healing polyurethane material: 80g PTMEG (polytetrahydrofuran ether diol, molecular weight 2000g / mol, 40mmol), 21g HMDI (dicyclohexylmethane diisocyanate, 80mmol) and 200mL DMAc (N,N-dimethylacetamide) were mixed and stirred at 80℃ for 3h to obtain a prepolymer; 3.484g adipic acid dihydrazide (20mmol) and a thymine-containing nucleobase chain extender (20mmol, thymine-1-acetic acid, CAS: 20924-05-4, Aladdin, catalog number: T130008) were added to the prepolymer and stirred at 80℃ for 3h to obtain a polyurethane material.

[0099] 3. Preparation of room temperature self-healing material assembled from nucleobase pairs: Two-dimensional graphene nanosheets were mixed in a polyurethane solution with a mass ratio of 200:1 and stirred at 40°C for 3 hours to obtain a self-healing material with a nacre-like structure.

[0100] 4. Preparation of self-healing coating: The self-healing material prepared in the above steps is cured at 80°C for 36 hours to obtain a room temperature self-healing coating with nucleobase pair assembly.

[0101] like Figure 2 The image shown is a scanning electron microscope (SEM) image of the self-healing material assembled from nucleobase pairs provided in this embodiment. The polyurethane contains parallel-aligned two-dimensional nanosheets. Clearly, the modified graphene two-dimensional nanosheets are arranged in parallel within the polyurethane, which is beneficial for improving the mechanical strength of the self-healing material. Simultaneously, the presence of high-density nucleobase pair hydrogen bonds at the polyurethane / graphene interface results in excellent stretchability.

[0102] See Figure 3 Figure 1 shows the tensile stress-strain curve of the self-healing material in this embodiment. As can be seen from the figure, its mechanical tensile strength and elongation at break are 46.6 MPa and 1736.9%, respectively, demonstrating excellent mechanical properties.

[0103] Furthermore, after the self-healing material was cut into two segments and then exposed to room temperature for 2 hours, its tensile strength recovered to 85.6%. This indicates that the polyurethane material in this embodiment exhibits rapid room-temperature functional self-healing capability through an energy diffusion mechanism constructed by the breaking-movement-reconstruction of main-chain hydrogen bonds, side-chain hydrogen bonds, and interfacial hydrogen bonds.

[0104] See Figure 4 and Figure 5 The images shown are scanning electron microscope (SEM) images and tensile stress-strain curves of the self-healing material after 2 hours of self-healing following shearing.

[0105] Furthermore, this embodiment also investigated the self-healing ability of the self-healing coating after 2 hours in low temperature (~2°C) and 3.5 wt.% saline solution, respectively. Figure 6 As shown, it can achieve self-healing even at low temperatures and in 3.5 wt.% saline, demonstrating outstanding aquatic environment and low-temperature self-repair capabilities.

[0106] By utilizing the difference in thermal expansion coefficients between the self-healing coating and the modified graphene two-dimensional nanosheets described in this embodiment, a crawling robot was assembled. This robot exhibits crawling behavior when driven by a near-infrared lamp, and its optical process is as follows: Figure 7 As shown.

[0107] In summary, the room temperature self-healing coating assembled from nucleobase pairs prepared in this embodiment has broad application prospects in the fields of metal corrosion protection and flexible crawling robots.

[0108] Example 2

[0109] This embodiment provides a method for preparing a room temperature self-healing coating assembled from nucleobase pairs, comprising the following steps:

[0110] 1. Graphene two-dimensional nanosheet modification: Cytosine modifier containing dynamic hydrogen bonds with a mass ratio of 1:10 was added to a CDI-activated graphene oxide dispersion of 0.1 mg / mL and stirred at 20 °C for 12 h, wherein the mass ratio of CDI to graphene oxide was 10:1.

[0111] 2. Preparation of self-healing polyurethane material: BDO (1,4-butanediol, 40 mmol), TDI (toluene diisocyanate, 80 mmol) and 100 mL DMSO (dimethyl sulfoxide) were blended and stirred at 60 °C for 5 h to obtain a prepolymer; 1.742 g adipic acid dihydrazide (10 mmol) and a guanine-containing nucleobase chain extender (30 mmol, guanine nucleoside, CAS No.: 118-00-3, Aladdin, catalog number: G103965) were added to the prepolymer and stirred at 30 °C for 20 h to obtain a polyurethane material.

[0112] 3. Preparation of room temperature self-healing coating with nucleobase pair assembly: Modified graphene two-dimensional nanosheets were mixed in a polyurethane solution with a mass ratio of 2000:1 and stirred at 25°C for 5 h to obtain a self-healing material with a nacre-like structure. Finally, the composite material was cured at 40°C for 60 h to obtain a room temperature self-healing coating with nucleobase pair assembly.

[0113] The self-healing properties of the self-healing polyurethane material prepared in this embodiment are similar to those in Example 1.

[0114] Example 3

[0115] This embodiment provides a method for preparing a room temperature self-healing coating assembled from nucleobase pairs, comprising the following steps:

[0116] 1. Graphene two-dimensional nanosheet modification: Guanine modifier containing dynamic hydrogen bonds with a mass ratio of 100:1 was added to a CDI-activated graphene oxide dispersion of 10 mg / mL and stirred at 80 °C for 4 h, wherein the mass ratio of CDI to graphene oxide was 100:1.

[0117] 2. Preparation of self-healing polyurethane material: PPG (polypropylene glycol, molecular weight 2000 g / mol, 40 mmol), IPDI (isophorone diisocyanate, 80 mmol) and 250 mL DMF (N,N-dimethylformamide) were blended and stirred at 100 °C for 2 h to obtain a prepolymer; 5.226 g of adipic acid dihydrazide (30 mmol) and a cytosine-containing nucleobase chain extender (10 mmol, N4-acetylcytosine, CAS No.: 14631-20-0, Aladdin, catalog No.: N103229) were added to the prepolymer and stirred at 70 °C for 2 h to obtain a polyurethane material.

[0118] 3. Preparation of room temperature self-healing coating with nucleobase pair assembly: Modified graphene two-dimensional nanosheets were mixed in a polyurethane solution with a mass ratio of 20:1 and stirred at 50°C for 0.5 h to obtain a self-healing material with a nacreous structure. Finally, the self-healing material was cured at 100°C for 10 h to obtain a self-healing coating with nucleobase pair assembly.

[0119] Example 4

[0120] This embodiment provides a method for preparing a room temperature self-healing coating assembled from nucleobase pairs, comprising the following steps:

[0121] 1. Graphene two-dimensional nanosheet modification: A uracil modifier containing dynamic hydrogen bonds with a mass ratio of 50:1 was added to a CDI-activated graphene oxide dispersion of 5 mg / mL and stirred at 40 °C for 6 h, wherein the mass ratio of CDI to graphene oxide was 50:1.

[0122] 2. Preparation of self-healing polyurethane material: PTMEG (molecular weight 1000 g / mol, 40 mmol), MDI (4,4'-diphenylmethane diisocyanate, 80 mmol) and 150 mL DMF+DMAc were blended and stirred at 70 °C for 4 h to obtain a prepolymer; 2.613 g adipic acid dihydrazide (15 mmol) and an adenine-containing nucleobase chain extender (25 mmol, adenine nucleoside, CAS No.: 58-61-7, Aladdin, catalog No.: A108806) were added to the prepolymer and stirred at 50 °C for 10 h to obtain a polyurethane material.

[0123] 3. Preparation of room temperature self-healing coating with nucleobase pair assembly: Modified graphene two-dimensional nanosheets were mixed in a polyurethane solution with a mass ratio of 1000:1 and stirred at 30°C for 4 hours to obtain a self-healing material with a nacre-like structure. Finally, the composite material was cured at 70°C for 40 hours to obtain a room temperature self-healing coating with nucleobase pair assembly.

[0124] Example 5

[0125] This embodiment provides a method for preparing a room temperature self-healing coating assembled from nucleobase pairs, comprising the following steps:

[0126] 1. Graphene two-dimensional nanosheet modification: Thymine modifier containing dynamic hydrogen bonds with a mass ratio of 20:1 was added to a CDI-activated graphene oxide dispersion of 1 mg / mL and stirred at 50℃ for 10 h, wherein the mass ratio of CDI to graphene oxide was 20:1.

[0127] 2. Preparation of self-healing polyurethane material: PPG (molecular weight 1000 g / mol, 40 mmol), HDI (80 mmol) and 200 mL DMSO + DMAc were blended and stirred at 90 °C for 2.5 h to obtain a prepolymer; 4.355 g adipic acid dihydrazide (25 mmol) and an adenine-containing nucleobase chain extender (15 mmol, adenine nucleoside, CAS No.: 58-61-7, Aladdin, catalog No.: A108806) were added to the prepolymer and stirred at 40 °C for 12 h to obtain a polyurethane material.

[0128] 3. Preparation of room temperature self-healing coating with nucleobase pair assembly: Modified graphene two-dimensional nanosheets were mixed in a polyurethane solution with a mass ratio of 500:1 and stirred at 45°C for 2 hours to obtain a self-healing material with a nacre-like structure. Finally, the composite material was cured at 60°C for 50 hours to obtain a room temperature self-healing coating with nucleobase pair assembly.

[0129] The mechanical properties of Examples 2-5 were tested. Similar to Example 1, the mechanical tensile strength was 10-50 MPa and the elongation at break was 1000-1800%. The ultimate tensile strength of the polyurethane coating cut into two pieces could recover 60%-90% after contact at room temperature for 0.5-12 hours. It could also achieve self-healing at low temperature and in 3.5 wt.% saline. Therefore, the technical solutions of Examples 2-5 can achieve the same technical effects as Example 1.

[0130] Comparative Example 1

[0131] This comparative example provides a method for preparing a room-temperature self-healing polyurethane material, including the following steps:

[0132] 80 g PTMEG (molecular weight 2000 g / mol, 40 mmol), 21 g HMDI (80 mmol) and 200 mL DMAc were blended and stirred at 80 °C for 3 h to obtain a prepolymer; 3.484 g adipic acid dihydrazide (20 mmol) and a thymine-containing nucleobase chain extender (20 mmol) were added to the prepolymer and stirred at 40 °C for 12 h to obtain a polyurethane material.

[0133] The prepared polyurethane material exhibited an ultimate tensile strength of 59.6 MPa and an elongation of 1112.4%, but it could not self-heal at room temperature. At 80°C, the mechanical strength of the material broken into two pieces recovered to 53.8 MPa after 2 hours of contact, with a mechanical strength repair efficiency of 90.3%.

[0134] Comparative Example 2

[0135] This comparative example provides a method for preparing a room-temperature self-healing polyurethane material, including the following steps:

[0136] BDO (40 mmol), TDI (80 mmol) and 100 mL DMSO were blended and stirred at 60 °C for 5 h to obtain a prepolymer; 1.742 g adipic acid dihydrazide (10 mmol) and a guanine-containing nucleobase chain extender (30 mmol) were added to the prepolymer and stirred at 30 °C for 20 h to obtain a polyurethane material.

[0137] The results of this comparative example are similar to those of Comparative Example 1, and it does not have a self-healing function at room temperature.

[0138] Comparative Example 3

[0139] This comparative example provides a method for preparing a room-temperature self-healing polyurethane material, including the following steps:

[0140] PPG (molecular weight 2000 g / mol, 40 mmol), IPDI (80 mmol) and 250 mL DMF were blended and stirred at 100 °C for 2 h to obtain a prepolymer; 5.226 g adipic acid dihydrazide (30 mmol) and a cytosine-containing nucleobase chain extender (10 mmol) were added to the prepolymer and stirred at 70 °C for 2 h to obtain a polyurethane material.

[0141] The results of this comparative example are similar to those of Comparative Example 1, and it does not have a self-healing function at room temperature.

[0142] In summary, this invention prepares a room-temperature self-healing coating assembled from nucleobase pairs by synergistically combining main-chain hydrogen bonds, side-chain hydrogen bonds, and interfacial hydrogen bonds. Specifically, modified graphene two-dimensional nanosheets are arranged in parallel within polyurethane due to the presence of high-density interfacial nucleobase pair hydrogen bonds. The room-temperature self-healing coating assembled from nucleobase pairs exhibits high mechanical strength due to the parallel arrangement of the nanosheets, and excellent stretchability due to the presence of multiple types of hydrogen bonds. It possesses rapid room-temperature functional self-healing capability through an energy diffusion mechanism constructed by the breakage-movement-reconstruction of multiple types of hydrogen bonds in polyurethane. Specifically, the mechanical tensile strength of the room-temperature self-healing coating assembled from nucleobase pairs is 10–50 MPa, and the elongation at break is 1000–1800%. Furthermore, after contact at room temperature for 0.5–12 hours, the ultimate tensile strength of the polyurethane coating cut into two segments can recover 60%–90%. The self-healing material obtained using the technical solution of this invention successfully balances the contradictions between high mechanical properties, excellent stretchability, and rapid room-temperature self-healing capability in the self-healing material system.

[0143] All aspects, embodiments, features, and examples of this invention are to be regarded as illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0144] The use of titles and descriptions in this invention does not imply limitation of the invention; each part can be applied to any aspect, embodiment, or feature of the invention.

[0145] Throughout this invention, wherever a composition is described as having, containing, or including specific components, or wherever a process is described as having, containing, or including specific process steps, it is contemplated that the compositions taught in this invention are also substantially composed of or comprised of the described components, and that the processes taught in this invention are also substantially composed of or comprised of the described process steps.

[0146] Unless otherwise specifically stated, the use of the terms “include, include, including” or “have, has, or having” should generally be understood as open-ended and non-restrictive.

[0147] It should be understood that the order of the steps or the order in which specific actions are performed is not particularly important, as long as the teachings of this invention remain operable. Furthermore, two or more steps or actions can be performed simultaneously.

[0148] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0149] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

Claims

1. A self-healing material based on nucleobase pair assembly, characterized in that, The invention includes a modified matrix material and modified graphene two-dimensional nanosheets; wherein the modified graphene two-dimensional nanosheets comprise graphene oxide modified with a modifier containing dynamic hydrogen bonds; the modified matrix material comprises a matrix material modified with a monomer containing hexa-hydrogen bonds and / or a nucleobase chain extender; and, the interface between the modified graphene two-dimensional nanosheets and the modified matrix material is formed with interfacial hydrogen bonds of nucleobase pairs, so that the modified graphene two-dimensional nanosheets are arranged in parallel in the modified matrix material. The modifier containing dynamic hydrogen bonds and the nucleobase chain extender each contain complementary base pairs for forming the nucleobase pairs; The nucleobase pair includes any one of the following combinations: thymine and adenine, cytosine and guanine, and uracil and adenine. The modifier containing dynamic hydrogen bonds includes any one of the nucleobases thymine, cytosine, uracil, adenine, and guanine; The nucleobase chain extender includes monomers containing pyrimidines or purines; The monomer containing six hydrogen bonds includes adipic acid dihydrazide monomer; The modified matrix material contains multiple types of hydrogen bonds, including a combination of two or three of the following: main chain hydrogen bonds, side chain hydrogen bonds, and interfacial hydrogen bonds. The energy diffusion mechanism constructed by the breaking-movement-reconstruction of the multi-type hydrogen bonds enables the self-healing material to have self-healing function at room temperature, low temperature or in water environment; The low temperature conditions are -2℃ to 5℃; the water environment is 0 to 5 wt.% saline solution; The main-chain hydrogen bonds are formed by introducing monomers containing six hydrogen bonds into the matrix material; And / or, the side-chain hydrogen bonds are formed by introducing the nucleobase chain extender into the matrix material; And / or, the interfacial hydrogen bonds are formed at the interface between the modified matrix material and the modified graphene two-dimensional nanosheets by embedding the modified graphene two-dimensional nanosheets in the modified matrix material. The method for preparing the modified graphene two-dimensional nanosheets includes: adding the modifier containing dynamic hydrogen bonds to the graphene oxide dispersion activated by N,N'-carbonyldiimidazole, and reacting at 20~80℃ for 4~12h to obtain the modified graphene two-dimensional nanosheets.

2. The self-healing material based on nucleobase pair assembly as described in claim 1, characterized in that, The pyrimidine monomers include any one of thymine, cytosine, and uracil; The monomers of the purine class include either adenine or guanine.

3. The self-healing material based on nucleobase pair assembly as described in claim 1, characterized in that, The mass ratio of the modifier containing dynamic hydrogen bonds to the graphene oxide is 1:10 to 100:1; In the graphene oxide dispersion, the mass ratio of N,N'-carbonyldiimidazole to graphene oxide is 10:1 to 100:1; The graphene oxide dispersion contains 0.1~10 mg / mL of graphene oxide; The graphene oxide has a diameter of 0.5~15μm and a thickness of 0.7~10 nm.

4. The self-healing material based on nucleobase pair assembly as described in claim 1, characterized in that, The self-healing material's repair functions include self-healing of mechanical properties and / or self-healing of salt water corrosion protection functions and / or self-healing of photothermal response crawling functions.

5. The self-healing material based on nucleobase pair assembly as described in claim 4, characterized in that, The self-healing mechanical properties mean that the tensile strength of the material recovers to 70%~90%.

6. A method for preparing a self-healing material based on nucleobase pair assembly as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Introduce one or both of the main chain hydrogen bonds and side chain hydrogen bonds into the prepolymer of the matrix material to obtain the modified matrix material; S2. A modifier containing dynamic hydrogen bonds is added to an N,N'-carbonyldiimidazole activated graphene oxide dispersion for reaction to obtain modified graphene two-dimensional nanosheets. S3. The modified graphene two-dimensional nanosheets and the modified matrix material are mixed and reacted to obtain the self-healing material.

7. The method for preparing the self-healing material as described in claim 6, characterized in that, In S1, the matrix material includes polyurethane; The method for preparing the modified matrix material includes blending a polyol, diisocyanate and organic solvent, and reacting at 60-100°C for 2-5 hours to obtain a prepolymer; adding one or a combination of two of adipic acid dihydrazide and nucleobase chain extender to the prepolymer and reacting at 30-70°C for 2-20 hours to obtain a polyurethane material. The diisocyanate comprises one of dicyclohexylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate; The polyol comprises at least one of polytetrahydrofuran, 1,4-butanediol, and polypropylene glycol; The organic solvent includes at least one of N,N-dimethylacetamide, dimethyl sulfoxide, and N,N-dimethylformamide; The mass ratio of the polyol to the organic solvent is 2:1 to 1:5; The molar ratio of the polyol to the diisocyanate is 1:1 to 1:2; The molar ratio of the polyol and adipic dihydrazide, and one or two of the nucleobase chain extender, is 1:1; In S2, the mass ratio of the modifier containing dynamic hydrogen bonds to the graphene oxide is 1:10 to 100:1; In the N,N'-carbonyldiimidazole activated graphene oxide dispersion, the mass ratio of N,N'-carbonyldiimidazole to graphene oxide is 10:1 to 100:1; The N,N'-carbonyldiimidazole activated graphene oxide dispersion contains 0.1~10 mg / mL graphene oxide; wherein the graphene oxide has a diameter of 0.5~15 μm and a thickness of 0.7~10 nm. In S3, the mass ratio of the modified matrix material to the modified graphene two-dimensional nanosheets is 2000:1 to 20:1; The mixing temperature is 25~50℃, and the reaction time is 0.5~5h.

8. A self-healing coating, characterized in that, The coating is obtained by curing the room temperature self-healing material based on nucleobase pair assembly as described in any one of claims 1-5, or the self-healing material based on nucleobase pair assembly prepared by the preparation method described in any one of claims 6-7. The curing temperature is 40~100℃ and the time is 10~60h.

9. The application of the self-healing material based on nucleobase pair assembly as described in any one of claims 1-5, or the self-healing material based on nucleobase pair assembly prepared by the preparation method as described in any one of claims 6-7, in the preparation of metal corrosion protection structures or flexible crawling robots.

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