A tough, self-healing functional material, its preparation method and application

Abstract

This application relates to the field of self-healing materials, specifically disclosing a high-toughness self-healing functional material, its preparation method, and its applications. This self-healing functional material is a supramolecular elastomer formed by in-situ free radical polymerization of the tetrad hydrogen-bonded monomer UPy-EMA, a host-guest inclusion complex, and an acrylate monomer under the action of a crosslinking agent and an initiator. The high-toughness self-healing functional material provided in this application is the first to effectively integrate multiple functions of "strength, toughness, self-healing, conductivity, and antibacterial properties," ultimately obtaining a self-repairing material that combines high strength and toughness, rapid self-healing at room temperature, conductivity, and antibacterial properties, with broad application prospects.

Description

Technical Field

[0001] This application relates to the field of self-healing materials, and more specifically, to a tough self-healing functional material, its preparation method, and its application. Background Technology

[0002] Self-healing materials have significant application value in flexible electronic devices and implantable medical devices, but their development has long been constrained by three core contradictions: the mutual exclusion of mechanical strength and self-healing properties, the conflict between functional integration and network dynamics, and the imbalance between environmental stability and practicality. Existing technological systems suffer from the following irreconcilable defects: I. Functional Singularity: The rigidity of dynamic network design makes it difficult to support functional requirements. Traditional hydrogels rely on only a single type of dynamic bond (such as hydrogen bonds or ionic bonds). Due to the lack of modifiable sites or steric hindrance in their molecular structure, it is difficult to introduce additional functional groups. The mutually exclusive contradiction between material function and self-healing properties remains unresolved. Regarding material conductivity, adding conductive fillers (such as carbon nanotubes or metal particles) to the building material hinders the recombination of dynamic bonds, thus reducing self-healing efficiency. To improve the bioactivity of the material, proteins or growth factors are often introduced, but this can trigger phase separation, leading to the disruption of the uniformity of the dynamic network.

[0003] II. Low Self-Healing Efficiency: Dynamic Bond Reorganization is Constrained by Both Kinetics and Thermodynamics. Traditional materials rely on random molecular diffusion for recombination, lacking a directional driving mechanism, resulting in low self-healing efficiency. During the self-repair process of material fracture, the dynamic bond recombination is disordered, and hydrogen bonds on the fracture surface are randomly connected, leading to a significant weakening of the interfacial strength compared to the bulk material.

[0004] III. Harsh Healing Conditions: Environmental Sensitivity Limits Material Practicality. The material's healing is highly dependent on humidity; when the relative humidity is below 40%, the healing efficiency of polyvinyl alcohol-borate gel decreases by 80% (leading to hydrogen bond competition failure). The material's healing is temperature-limited; the temperature must be above 60°C for hydrogels based on the Diels-Alder reaction to trigger the reverse reaction. This limitation prevents the material from being used in living organisms. The material's healing requires external force; 90% of traditional hydrogels require pressure to bring the fracture surfaces together, which is difficult to achieve in practice.

[0005] Therefore, there is an urgent need to provide a new type of self-healing functional material. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a tough, self-healing functional material, its preparation method, and its application.

[0007] The technical solution adopted in this application is as follows: In a first aspect, this application provides a tough self-healing functional material, which is a supramolecular elastomer formed by in-situ free radical polymerization of the quadruple hydrogen bond monomer UPy-EMA, a host-guest inclusion complex, and an acrylate monomer under the action of a crosslinking agent and an initiator. The tetrahydrobonded monomer UPy-EMA is ureidopyrimidinone ethyl methacrylate; The host molecule in the host-guest inclusion complex is a carbon nanotube composite material, which is compounded with single-walled carbon nanotubes through π-π stacking via a pyrene-functionalized β-cyclodextrin derivative, denoted as Py-β-CD / SWCNT; the guest molecule is an adamantane-functionalized acrylate monomer, denoted as HEMA-Ad.

[0008] Furthermore, the molar ratio of the aforementioned tetrahydrobonded monomer UPy-EMA, host-guest inclusion complex, and acrylate monomer is 1:1:4-6.

[0009] Furthermore, the acrylate monomers participating in the free radical polymerization reaction include at least one of 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, and 2-methoxypropyl acrylate.

[0010] Furthermore, the structural formula of the above HEMA-Ad is: Ad-C(O)-O-(CH2)2-OC(O)-C(R2)=CH2, where R2 is H or CH3.

[0011] Furthermore, in the above-mentioned host-guest inclusion complex, the molar ratio of the host molecule to the guest molecule is 1:1.2-1.8.

[0012] Furthermore, in the above-mentioned host-guest inclusion complex, the content of SWCNT in the host material Py-β-CD / SWCNT is 6-10 wt%.

[0013] Furthermore, the above-mentioned self-healing functional material has a tensile strength ≥0.39MPa, an elongation at break ≥550%, and a conductivity ≥5.55 S / m; after three self-healing cycles, the mechanical efficiency is ≥50% and the electrical efficiency is ≥95%.

[0014] Secondly, this application provides a method for preparing the above-mentioned tough and self-healing functional material, comprising: (1) Carbon nanotube composite material was included with adamantane-functionalized acrylate monomer in a solvent to form a host-guest inclusion complex. The specific inclusion of β-CD cavity with adamantane was verified by the characteristic correlation peak δ (3.65, 1.84) in 2D NOESY spectrum. (2) 2-Amino-4-hydroxy-6-methylpyrimidine was reacted with isocyanate methyl methacrylate at 160-180 °C in DMSO to obtain the tetrad hydrogen bond monomer UPy-EMA, and the structure was verified by the hydrogen bond proton peaks in ¹H NMR (δ 12.93, 11.90). (3) The host-guest inclusion complex, the four-fold hydrogen bond monomer UPy-EMA, the acrylate monomer, the crosslinking agent, and the initiator are mixed in a solvent and formed by in-situ free radical polymerization.

[0015] Furthermore, the above-mentioned in-situ free radical polymerization reaction is carried out by polymerization in an inert environment at 50-55°C for 2 hours.

[0016] Furthermore, the above-mentioned carbon nanotube composite material is prepared by the following steps: combining Py-β-CD and SWCNT in an alkaline aqueous solution by ultrasonic treatment; The preparation methods of Py-β-CD include: (a) β-cyclodextrin was reacted with p-toluenesulfonyl chloride to give 6-sulfonated β-CD, denoted as 6-TsO-β-CD; (b) React 6-TsO-β-CD with ammonia water, and the sulfonyl group is replaced by an amino group to give 6-NH2-β-CD; (c) In the presence of a condensing agent, 6-NH2-β-CD is amidated with a pyrenic acid compound to obtain Py-β-CD.

[0017] Thirdly, this application provides an application of the above-mentioned tough self-healing functional material, applying the self-healing functional material to the biomedical field related to self-healing flexible sensors or wearable devices.

[0018] In summary, this application has the following beneficial effects: 1. Traditional self-healing materials are limited by the contradiction between the strength and self-healing properties of dynamic bonds and functional integration bottlenecks. This invention crosslinks the quadruple hydrogen-bonded monomer UPy-EMA with a host-guest inclusion complex and an acrylate monomer to form a dual dynamic network: UPy-EMA provides instantaneous recombination capability, compensating for the slow kinetics of host-guest interactions; the host-guest inclusion complex provides high binding energy and directionality, inhibiting hydrogen bond failure under humid conditions. The two components covalently couple to construct an intramolecular synergistic dynamic network, eliminating bond recombination steric hindrance and achieving defect-free interfacial repair.

[0019] 2. This application achieves a fundamental breakthrough in intramolecular synergistic dynamic network design. Its core lies in the stable composite of β-cyclodextrin (β-CD) host molecules with single-walled carbon nanotubes (SWCNTs) through π-π stacking after pyrene functionalization, constructing a carbon nanotube composite material with both conductivity and drug-carrying cavity as a nano-reinforcing unit; at the same time, it innovatively designs adamantane functionalized guest molecule (HEMA-Ad provides antibacterial hydrophilicity), forming a host-guest inclusion complex through host-guest inclusion interaction.

[0020] 3. The tough self-healing functional material provided in this application has excellent mechanical properties, with a tensile strength of 0.39 MPa, an elongation at break of more than 550%, and a conductivity of ≥5.55 S / m; and it has excellent self-healing ability, with a mechanical efficiency of ≥50% and an electrical efficiency of ≥95% after three self-healing cycles.

[0021] 4. The tough self-healing functional material provided in this application retains drug loading capacity in the β-CD cavity, achieves conductive self-healing synergy with SWCNT, and simultaneously imparts high antibacterial rate with adamantane guest. For the first time, the multi-functionality of "toughness-self-healing-conductivity-antibacterial" is effectively integrated, and finally a self-repairing material with high strength and toughness, rapid self-healing at room temperature, conductivity and antibacterial properties is obtained, which has broad application prospects. Attached Figure Description

[0022] Figure 1 This is the synthetic route for the host-guest inclusion complex PHEMA-SWCNT-β-CD prepared in Example 1; Figure 2 This is the two-dimensional NMR (2D NOESY) spectrum of the host-guest inclusion complex obtained in Example 1; Figure 3 This is the MS spectrum of the tetrahydrobonded monomer prepared in Example 1; Figure 4 It is the tetrahydrobonded monomer prepared in Example 1. 1 H NMR characterization spectrum; Figure 5 These are the cyclic tensile test results of the functional material prepared in Example 1; Figure 6 This is the result of the change in proximity sensing resistance of the functional material prepared in Example 1; Figure 7 These are the mechanical self-healing cycle test results of the functional material prepared in Example 1; Figure 8 These are the qualitative test results of the electrical self-healing properties of the functional material prepared in Example 1; Figure 9 These are the quantitative results of the electrical self-healing properties of the functional materials prepared in Example 1; Figure 10These are the results of the electrical self-healing cycle test of the functional material prepared in Example 1; Figure 11 These are the DSC analysis results of the functional materials prepared in Example 1; Figure 12 These are the results of the moisture absorption performance test of the functional material prepared in Example 1. Detailed Implementation

[0023] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Specific conditions not specified in the examples shall be carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0024] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0025] Preparation Example 1 This preparation example provides the host molecule Py-β-CD / SWCNT, and its preparation method includes: (1) Synthesis of 6-p-toluenesulfonyl-β-cyclodextrin (6-TsO-β-CD) Dissolve 25 g of β-cyclodextrin in 600 mL of deionized water, slowly add 6.5 g of p-toluenesulfonyl chloride, and stir overnight at room temperature. Add 10 g of NaOH (dissolved in 100 mL of water), filter, add 30 g of NH4Cl to adjust the pH to 8, cool at 4 °C overnight, and recrystallize the aqueous phase three times to obtain 6-TsO-β-CD with a yield of 29.8%. Mass spectrometry characterization showed the presence of 1311 [M+Na]. + and 1287 [MH] - Ion peak.

[0026] (2) Synthesis of 6-amino-β-cyclodextrin (6-NH2-β-CD) 6-TsO-β-CD was dissolved in excess ammonia water, stirred in an oil bath at 75°C for 4 hours, cooled, and precipitated with acetone. The precipitate was dissolved in H2O / CH3OH (3:1, v / v), and precipitated three more times with acetone. After drying, 6-NH2-β-CD was obtained in 43.5% yield. Mass spectrometry showed 1157 [M+Na]. + and 1133 [MH] - Ion peak.

[0027] (3) Synthesis of pyrene-modified β-cyclodextrin (Py-β-CD) Dissolve 250 mg of 6-NH2-β-CD and 174 mg of 1-pyrenebutyric acid in 10 mL of DMF, add 200 mg of DCC and 50 mg of HOBT, and stir for 5 days at 0 °C under argon protection. After filtration, precipitate with acetone, wash the precipitate with water to remove unreacted raw materials, and dry under vacuum to obtain Py-β-CD with a yield of 69.2%. 1 In the 1H NMR, δ8.29–8.11 represents the hydrogen signal from the pyrene ring.

[0028] (4) Preparation of Py-β-CD / SWCNT 73.8 mg of Py-β-CD was dissolved in 0.1 mol / L NaOH solution, and 12.3 mg of single-walled carbon nanotubes (SWCNTs) were added. After sonication for 5 hours, the mixture was centrifuged, and the supernatant was dialyzed for 7 days (using 0.1 mol / L NaOH for the first 5 days and deionized water for the last 2 days). The product was then freeze-dried to obtain the final product. The SWCNT content was 6 wt%, and thermogravimetric analysis showed that the β-CD grafting rate on the SWCNT surface was 75.6%.

[0029] Preparation Example 2 This preparation example provides a guest molecule, HEMA-Ad, whose preparation method includes: (1) Synthesis of 1-adamantanoyl chloride Take 2.3g of 1-adamantane carboxylic acid and mix it with 20mL of SOCl2. Stir at 80℃ for 2 hours. After the solvent is evaporated, azeotropically react with dichloromethane twice to obtain 1-adamantane chlorohydrin.

[0030] (2) Synthesis of hydroxyethyl methacrylate-adamantane ester (HEMA-Ad) 1 mL of hydroxyethyl methacrylate (HEMA) and 1.6 mL of triethylamine were dissolved in 100 mL of dichloromethane. 1.85 g of 1-adamantanoyl chloride (dissolved in 30 mL of dichloromethane) was added dropwise under ice bath conditions. After the addition was complete, the reaction was allowed to proceed for 5 hours. The solution was then washed successively with 1 mol / L hydrochloric acid, 1 mol / L sodium bicarbonate, and pure water, and dried over anhydrous sodium sulfate to obtain a pale yellow liquid, HEMA-Ad, with a yield of 74.3%. A characteristic peak appeared at δ 4.2 in 1H NMR.

[0031] Example 1

[0032] This embodiment provides a tough, self-healing functional material, the preparation method of which includes: (1) Assembly of the subject-guest inclusion complex: According to the host molecule: guest molecule = 1:1.5 (molar ratio), 1 mg of Py-β-CD / SWCNT (375 μL black solution, provided by Preparation Example 1) was dissolved in DMSO, 2 mg of HEMA-Ad (provided by Preparation Example 2) was added, and the mixture was stirred, assembled, and then freeze-dried.

[0033] The correlation signals between β-CD (δ3.3-3.8) and Ad (δ1.5-2.0) were observed by two-dimensional nuclear magnetic resonance (2D NOESY), and the formation of inclusion complexes was verified by two-dimensional infrared spectroscopy (2D IR).

[0034] (2) Synthesis of the tetrahydrobonded monomer UPy-EMA: 1 g of 2-amino-4-hydroxy-6-methylpyrimidine (8 mmol) was dissolved in DMSO, heated in an oil bath to 170 °C, and then removed. 1.25 mL of isocyanate methacrylate (8.8 mmol) was quickly added, and the mixture was stirred in a water bath at 20 °C for 20 minutes to form a white precipitate. After filtration, the precipitate was washed three times with cyclohexane and dried to obtain UPy-EMA. The 1H NMR was used to characterize the precipitate, and hydrogen bond-related signals were observed at δ 12.93 and 11.90.

[0035] (3) Copolymerization preparation of elastomers: 2 mL of 2-methoxyethyl acrylate (MEA), 200 mg of host-guest inclusion complex, and UPy-EMA (in a molar ratio of 1:1 to host-guest inclusion complex) were dissolved in 10 mL of tetrahydrofuran. After ultrasonic dispersion, 5 mg of azobisisobutyronitrile (initiator, AIBN) and 2 μL of ethylene glycol dimethacrylate (crosslinking agent, EGDMA) were added. After deoxygenation by argon bubbling, polymerization was carried out in an oil bath at 52 °C. The solvent was removed by drying to obtain a supramolecular elastomer.

[0036] Example 2

[0037] This embodiment provides a tough self-healing functional material, which differs from Embodiment 3 in that: in step (3), the molar ratio of the host-guest inclusion complex to UPy-EMA is 1:0.8.

[0038] Example 3

[0039] This embodiment provides a tough self-healing functional material, which differs from Embodiment 3 in that: in step (3), the molar ratio of the host-guest inclusion complex to UPy-EMA is 1:1.2.

[0040] Example 4

[0041] This embodiment provides a tough, self-healing functional material, which differs from Embodiment 3 in that: In step (3), the acrylate monomer is 2-ethoxypropyl acrylate (2 mL added).

[0042] Example 5

[0043] This embodiment provides a tough self-healing functional material, which differs from Example 3 in that: in step (1), Py-β-CD / SWCNT (provided by Example 1) is dissolved in DMSO according to the molar ratio of host molecule: guest molecule = 1:1.2, and HEMA-Ad (provided by Example 2) is added, stirred and assembled, and then freeze-dried.

[0044] Example 6

[0045] This embodiment provides a tough self-healing functional material, which differs from Example 3 in that: in step (1), Py-β-CD / SWCNT (provided by Example 1) is dissolved in DMSO according to the molar ratio of host molecule: guest molecule = 1:1.8, HEMA-Ad (provided by Example 2) is added, and after stirring and assembly, it is freeze-dried.

[0046] Performance testing

[0047] I. Structural verification of key intermediates in self-healing functional materials: 1. Structural identification and significance of host-guest inclusion complexes Figure 1 This application describes the synthetic route of the host-guest inclusion complex PHEMA-SWCNT-β-CD. Through the host-guest inclusion interaction between β-CD (SWCNT surface) and Ad (HEMA-Ad terminal), SWCNT is "anchored" to the HEMA network: the inclusion complex acts as a crosslinking point, enabling the HEMA molecular chains and SWCNT to form a three-dimensional network structure.

[0048] Two-dimensional NMR (2D NOESY) analysis was performed on the host-guest inclusion complex prepared in Example 1, and the results are as follows: Figure 2 As shown. By Figure 2 As can be seen, two-dimensional NMR (2D NOESY) showed a correlation between the H (δ3.3-3.8) of β-CD and the H (δ1.5-2.0) of Ad, indicating that the host-guest inclusion complex is not a "simple mixed system" of SWCNT particles dispersed in the PHEMA matrix, but rather achieves "structural synergy" through the presence of host-guest inclusion, that is, the two achieve "structural synergy" through supramolecular interaction.

[0049] Regarding the significance of the inclusion complex for self-healing materials: The inclusion complex provides a dynamic cross-linked framework for the material through the host-guest inclusion interaction of β-cyclodextrin (β-CD, grafted onto the SWCNT surface) and adamantane (Ad, grafted onto the HEMA monomer), thus possessing both elasticity and self-healing capabilities. In the inclusion complex, β-CD and Ad are assembled at a molar ratio of 1:1.5. The inclusion interaction acts as a "dynamic cross-linking point," allowing the SWCNTs, after copolymerization with HEMA, to form a three-dimensional network structure. The inclusion complex anchors the SWCNTs to the PHEMA matrix, preventing aggregation while allowing the molecular chains to slip under stress. Mechanical characterization shows that the material containing the inclusion complex has a maximum elongation at break of 901.8% (0wt% SWCNT content), maintaining 325.0% even with 20wt% SWCNTs. Furthermore, after three cycles of tensile testing, it essentially recovers to its initial state, demonstrating the flexibility and elastic recovery of the cross-linked network.

[0050] When the material is damaged, the host-guest inclusion complex (Ad-β-CD) breaks at the fracture surface, exposing free β-CD and Ad. Upon re-contact, the groups rapidly rebuild the inclusion complex, restoring electrical properties within 20 seconds. Comparative experiments show that the PHEMA / SWCNT physical hybrid material without inclusion complexes cannot self-heal, further demonstrating that the host-guest inclusion complex is the core driving force for self-healing.

[0051] Both the host and guest molecules of a host-guest inclusion complex are crucial to the performance of self-healing materials because: 1) Main molecule (Py-β-CD / SWCNT) The host molecule is based on a single-walled carbon nanotube (SWCNT), and the surface is grafted with β-cyclodextrin (Py-β-CD) modified with 1-pyrene butyric acid. The hydrophobic cavity of β-CD has a strong specific inclusion effect with the adamantane (Ad) in the guest molecule HEMA-Ad.

[0052] SWCNTs are uniformly dispersed in the matrix through the π-π stacking effect of Py-β-CD, forming a continuous conductive network with intertwined structures. With a SWCNT content of 10 wt%, the material's conductivity reaches 5.55 S / m, and its electrical efficiency remains ≥95% after three self-healing processes. If SWCNTs are removed (pure PHEMA system), the material becomes completely non-conductive. Simultaneously, SWCNTs, as a nano-reinforcing phase, can inhibit crack propagation within the PHEMA matrix. Increasing the SWCNT content from 0 wt% to 20 wt% increases the maximum tensile stress from 0.04 MPa to 0.37 MPa and the Young's modulus from 0.13 MPa to 0.45 MPa, demonstrating that SWCNTs are crucial for the material's mechanical strength, preventing insufficient strength due to excessive flexibility in the host-guest cross-linked network.

[0053] 2) Guest molecule (HEMA-Ad) Ad, as a guest group, has a molecular size (approximately 0.7 nm in diameter) that perfectly matches the cavity of β-CD (0.6-0.8 nm in inner diameter), enabling the rapid formation of stable inclusion complexes. Furthermore, the inclusion of Ad with β-CD is dynamically reversible—when the material fractures, the inclusion complex dissociates, exposing free Ad at the fracture surface. Upon re-contact, it can re-include with the host β-CD, which is the core driving force of self-healing.

[0054] The HEMA segments in HEMA-Ad have the same structure as the polymer monomer HEMA, allowing for seamless integration into the PHEMA matrix during copolymerization and preventing phase separation due to poor compatibility between the guest molecules and the matrix. Simultaneously, the HEMA segments contain hydrophilic hydroxyl groups (-OH), which enhance the mobility of the polymer molecular chains. DSC data shows that PHEMA has a glass transition temperature (Tg) of 8.4-17.1℃ (below room temperature), and the molecular chains are in a highly elastic state at room temperature, making it easier for the boundary groups at the fracture surface to contact after the material breaks, thus aiding in the reconstruction of host-guest interactions.

[0055] 3) Subject-object synergy Without the host β-CD / SWCNT: the material lacks dynamic binding sites and conductive network, cannot self-heal and does not have conductive function; Without guest molecules, Ad-HEMA: the host β-CD / SWCNT cannot crosslink with the PHEMA matrix, SWCNT is prone to agglomeration, and the material's mechanical properties and self-healing efficiency are greatly reduced; Only when the host β-CD / SWCNT and the guest HEMA-Ad combine through a precisely matched host-guest interaction can an integrated structure of "dynamic cross-linking network (host-guest interaction) + conductive network (SWCNT) + elastic matrix (HEMA)" be constructed, enabling the material to simultaneously possess the properties of room temperature self-healing (mechanical efficiency ≥50%), high conductivity (5.55S / m), and high elasticity (elongation at break 621.7%).

[0056] 2. Structural identification of the tetrahydrobonded monomer UPy-EMA The four-hydrogen-bonded monomer prepared in Example 1 was used as a sample for determination.

[0057] (1) MS analysis was performed, and the results are as follows: Figure 3 As shown, [M+H] appears in the MS spectrum. + , [M+Na] + Positive ion peak and [MH] - The negative ion peak indicates the presence of UPy-EMA (M=278) in the product.

[0058] (2) The structure and purity of the compound were characterized by nuclear magnetic resonance, with CDCl3 as the solvent.

[0059] 1 The H NMR characterization results are as follows Figure 4 As shown in the spectrum, isomerization of the carbonyl group and double bond on the pyrimidine ring produces a phenolic hydroxyl signal, and intramolecular hydrogen bonding occurs in the product, resulting in absorption signals at δ 12.93 and 11.90. Other hydrogen absorption peaks in the compound structure have been identified in the spectrum. The peak positions and integrated areas indicate that the compound was successfully synthesized.

[0060] II. Material Property Characterization The mechanical properties, electrical properties, and self-healing properties of the self-healing functional material synthesized according to the method of Example 1 of this application were characterized.

[0061] (a) Mechanical property testing 1. Cyclic tensile tests were performed on the self-healing material provided in Example 1, and the results are as follows: Figure 5 As shown, this demonstrates that the material has excellent resilience. After three cycles of stretching, the material basically returns to its initial state, and its mechanical properties do not decrease by an order of magnitude.

[0062] 2. The mechanical properties of the polymer materials were characterized by a universal tensile testing machine, and the effect of SWCNT content on the mechanical properties of the self-healing functional materials was investigated, with the SWCNT content as a variable (all synthesized according to the method of Example 1). The results are shown in Table 1.

[0063] Table 1. Characterization of mechanical properties of materials

[0064] As can be seen from Table 1: The content of SWCNTs has a significant impact on mechanical properties. The maximum tensile stress and Young's modulus increase significantly with increasing SWCNT content. When the SWCNT content reaches 8 wt%, the Young's modulus (0.39 MPa) meets the requirements; with further increases in content, both the maximum tensile stress and Young's modulus increase further, fully meeting the requirements (tensile strength ≥ 0.39 MPa). When the SWCNT content is 8–10 wt%, the elongation at break is higher than 550%.

[0065] The material exhibits a certain degree of self-healing ability after damage, retaining some tensile stress after healing, and this value increases with the increase of SWCNT content (from 0.02 MPa to 0.19 MPa). The elongation at break after healing is significantly lower than that in the initial state, but still maintains a certain degree of ductility, indicating that the addition of SWCNTs not only improves strength but also endows the material with a certain structural recovery capability.

[0066] This indicates that the addition of SWCNTs significantly improves the stiffness and strength of PHEMA composites, but reduces their ductility. At an SWCNT content of 8–10 wt%, the material can maintain a high elongation at break (>550%) while meeting tensile strength requirements, representing an optimal range for balancing strength and toughness. The composite also exhibits certain self-healing properties, with the mechanical properties after healing positively correlated with the SWCNT content.

[0067] (ii) Electrical performance testing 1. Conductivity measurement: The conductivity of SWCNTs with different contents (6wt%-20wt%) was measured using an SZT-2A four-probe tester. The results are as follows: Figure 2 As shown.

[0068] Table 2. Characterization of electrical properties of materials

[0069] Note: c = b / a As shown in Table 2, when the SWCNT content is 10wt%, the electrical conductivity of the material is 5.55±0.09 S / m; when it is 20wt%, it is 7.76±0.11 S / m, both ≥5.55 S / m. The electrical conductivity increases with the increase of SWCNT content, which clearly meets the conductivity index.

[0070] 2. Conductivity stability: Conductivity was measured simultaneously under tensile conditions, and the results are as follows: Figure 5 As shown, the performance did not decrease significantly when the strain was 300%.

[0071] 3. Proximity sensing: The resistance changes of a finger, a plastic rod, and a metal rod were measured when they were brought close together using an HP 4284A LCR meter with a sample size of 1.5×1.5×1cm.

[0072] The results are as follows Figure 6 As shown, when a finger approaches the material surface, the material's conductivity increases and its resistance decreases. When a conductive metal rod and an insulated plastic rod approach the material surface, the change in conductivity is minimal. This indicates that the composite material possesses certain human contact and sensing characteristics, and has potential application value in fields such as proximity sensing, sensing materials, and electronic skin.

[0073] (III) Self-healing performance test 1. Mechanical self-healing: The mechanical self-healing properties of an elastomer are determined by the maximum tensile strength of the material before and after self-healing. The tensile strength of the initial specimen was measured, then the specimen was cut, and the fracture surfaces were rejoined. The stress-strain curves of the material were measured at different healing times.

[0074] Determine the initial tensile strength T initial After the fracture surfaces healed upon contact, the post-healing strength T was measured. healed Calculate the mechanical self-healing efficiency (η) mech The self-healing cycle was tested three times. Mechanical self-healing efficiency (η) mech η is calculated according to the following formula: mech =T healed / T initial , among which, T initial The tensile strength of the initial spline, T healed The tensile strength of the specimen after healing.

[0075] The results are as follows Figure 7 As shown, the self-healing efficiency of the material can still reach 50% after three cut-and-heal cycles, indicating that the composite material has excellent mechanical self-healing ability.

[0076] 2. Electrical self-healing: (1) Qualitative testing: such as Figure 8 As shown, the material is connected in series with a 3V circuit and an LED. When the circuit is cut off, the LED goes out, and it lights up again after the circuit is repaired.

[0077] (2) Quantitative determination: The conductivity was measured with four probes at the initial and post-healing stages, and the resistance change was calculated and tracked. By measuring the conductivity of the composite before and after self-healing (three times), the electrical self-healing efficiency (η) of the material was quantitatively calculated according to the following formula. elec ):η elec =E healed / E initial E initial The electrical conductivity of the initial sample, E healed The electrical conductivity of the sample after healing.

[0078] The results are as follows Figure 9 and Figure 10 As shown, the electrical properties of this composite material can be restored in a very short time, indicating a high functional healing rate. Furthermore, the electrical properties of the composite material remain above 95% after three self-healing cycles.

[0079] (iv) Thermal and structural verification 1. Thermal properties: The glass transition temperature (Tg) was measured using DSC (TA Q2000), and the tanδ- temperature curve was measured using DMA (TA Q800) to verify that Tg was lower than room temperature; thermal stability was measured using TGA (EXSTAR 6000).

[0080] The measured thermal weight loss of the prepared composite material reached 75.6%, indicating that the mass fraction of cyclodextrin grafted onto the surface of carbon nanotubes was 75.6%.

[0081] 2. DSC analysis was performed on composite materials with different SWCNT contents (6 wt%~20 wt%) to characterize the material properties, explore the mechanism of elasticity of the material at room temperature, and characterize the glass transition temperature (Tg) of the material.

[0082] The results are as follows Figure 11 As shown, the glass transition temperatures of the samples are all below room temperature, thus exhibiting elasticity at room temperature.

[0083] (v) Verification of moisture absorption performance A Noske-Kaeser KSP-252 humidity chamber was used. The humidity was adjusted at 25℃ (33%-100% RH). After equilibration for 48 hours, the moisture absorption rate was calculated by weighing. The resistance was measured simultaneously, and the humidity-resistance correlation was analyzed.

[0084] The results are as follows Figure 12 As shown, this composite material exhibits extremely high electrical sensitivity to humidity. This indicates that by constructing a dual dynamic covalent network (UPy + host-guest) and stably integrating SWCNTs within it, the resulting material is not only expected to possess excellent sensing performance but may also achieve intelligent self-healing functionality triggered by ambient humidity, demonstrating advanced capabilities and environmental adaptability surpassing traditional composite materials.

[0085] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-toughness, self-healing functional material, characterized in that, The self-healing functional material is a supramolecular elastomer formed by in-situ free radical polymerization of the quadruple hydrogen-bonded monomer UPy-EMA, host-guest inclusion complex, and acrylate monomer under the action of crosslinking agent and initiator. The tetrahydrobonded monomer UPy-EMA is ureidopyrimidinone ethyl methacrylate; The host molecule in the host-guest inclusion complex is a carbon nanotube composite material, which is compounded with single-walled carbon nanotubes through π-π stacking via a pyrene-functionalized β-cyclodextrin derivative, denoted as Py-β-CD / SWCNT; the guest molecule is an adamantane-functionalized acrylate monomer, denoted as HEMA-Ad.

2. The high-toughness self-healing functional material according to claim 1, characterized in that, The molar ratio of the quadruple hydrogen-bonded monomer UPy-EMA to the host-guest inclusion complex is 1:0.5-1.

5.

3. The high-toughness self-healing functional material according to claim 2, characterized in that, The acrylate monomers participating in the free radical polymerization reaction include at least one of 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-methoxypropyl acrylate, and 2-ethoxypropyl acrylate.

4. The high-toughness self-healing functional material according to claim 1, characterized in that, The structural formula of HEMA-Ad is: Ad-C(O)-O-(CH2)2-OC(O)-C(R2)=CH2, where R2 is H or CH3.

5. The high-toughness self-healing functional material according to claim 1, characterized in that, In the host-guest inclusion complex, the molar ratio of the host molecule to the guest molecule is 1:1.2-1.

8.

6. The high-toughness self-healing functional material according to any one of claims 1-5, characterized in that, In the host-guest inclusion complex, the mass fraction of SWCNT in the host material Py-β-CD / SWCNT is 6-10 wt%.

7. A method for preparing a tough, self-healing functional material according to any one of claims 1-6, characterized in that, It includes: (1) Carbon nanotube composite material was included with adamantane-functionalized acrylate monomer in a solvent to form a host-guest inclusion complex. The specific inclusion of β-CD cavity with adamantane was verified by the characteristic correlation peaks δ3.3-3.8 and δ1.5-2.0 in 2D NOESY spectrum. (2) 2-Amino-4-hydroxy-6-methylpyrimidine was reacted with isocyanate methyl methacrylate at 160-180 °C in DMSO to obtain the tetrad hydrogen bond monomer UPy-EMA, and the structure was verified by the hydrogen bond proton peaks in ¹H NMR (δ 12.93, 11.90). (3) The host-guest inclusion complex, the four-fold hydrogen bond monomer UPy-EMA, the acrylate monomer, the crosslinking agent, and the initiator are mixed in a solvent and formed by in-situ free radical polymerization.

8. The method for preparing the tough, self-healing functional material according to claim 7, characterized in that, The in-situ free radical polymerization reaction is carried out by polymerization at 50-55°C for 2 hours in an inert environment.

9. The method for preparing the high-toughness self-healing functional material according to claim 7, characterized in that, The carbon nanotube composite material is prepared by the following steps: combining Py-β-CD and SWCNT in an alkaline aqueous solution by ultrasonic treatment; The preparation method of the Py-β-CD includes: (a) β-cyclodextrin was reacted with p-toluenesulfonyl chloride to give 6-sulfonated β-CD, denoted as 6-TsO-β-CD; (b) React 6-TsO-β-CD with ammonia water, and the sulfonyl group is replaced by an amino group to give 6-NH2-β-CD; (c) In the presence of a condensing agent, 6-NH2-β-CD is amidated with a pyrenic acid compound to obtain Py-β-CD.

10. An application of a tough, self-healing functional material according to any one of claims 1-5, characterized in that, The self-healing functional material can be applied to biomedical fields related to self-healing flexible sensors or wearable devices.

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