A method for real-time visualization and autonomous quantitative evaluation of the repair process of a self-healing material

Abstract

The application discloses a kind of real-time visualization and autonomous quantitative evaluation method of self-healing material repair process, first establish "repair degree-time" standard curve, "fluorescence characteristic-time" standard atlas and "fluorescence color-time" standard color chart, then "repair degree-fluorescence characteristic-time" standard atlas and "repair degree-fluorescence color-time" standard atlas are established by time variable, the fluorescence characteristic parameter of damage area is determined, fluorescence characteristic parameter is compared with the "repair degree-fluorescence characteristic-time" standard atlas established, obtains the equivalent repair degree reached by current damage area, or by observing the macro fluorescence color of damage area, and "repair degree-fluorescence color-time" standard atlas is directly compared and estimated repair degree.The application promotes self-healing evaluation from qualitative indication to quantitative characterization, and provides new data dimension for precise evaluation and life prediction of material service state.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary technical field of intelligent response materials and structural health monitoring. Specifically, it relates to a method for non-destructive real-time quantification of the self-healing process and mechanical property recovery after material damage by utilizing the characteristic that fluorescence signals change regularly with the evolution of the internal physicochemical state of self-healing materials. Background Technology

[0002] Self-healing materials are composite materials that encapsulate microcapsules within a polymer matrix. By embedding microcapsules containing healing agents within the matrix, the material can autonomously repair itself after damage. However, the core bottleneck of existing technologies lies in the fact that the repair process is a "black box," making it impossible to effectively assess the initiation, progress, and completion of the repair. Although some studies have attempted to introduce fluorescent dyes or single aggregation-induced emission (AIE) molecules for damage indication, their functions are mostly limited to static, qualitative labeling of the damage location. There is a lack of quantifiable and intrinsic correlation between the fluorescence signal and the chemical process of the healing reaction, as well as the final recovery of mechanical properties. This makes it impossible for users to accurately determine whether the repair is sufficient or whether the material has been restored to a safe service condition.

[0003] Therefore, there is an urgent need in this field for an intelligent material system that can deeply integrate self-healing function with real-time, visualized, and quantifiable monitoring capabilities of the repair status, especially to overcome the limitations of single or a few fluorescent molecules in response through the synergistic design of multiple fluorescent components. This invention aims to construct a multi-dimensional fluorescence response network by synergistically combining at least two AIE components, thereby solving the quantitative accuracy and applicability issues of existing technologies, and providing an integrated solution capable of dynamically tracking and quantitatively evaluating the entire "damage-repair-healing completion" process. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned defects of the prior art and provide a real-time visualization and autonomous quantitative assessment method for the repair process of self-healing materials. The core of this method is to establish a definite quantitative relationship between the internal repair state (such as the degree of chemical curing), macroscopic mechanical properties and non-destructively detectable fluorescence signal parameters of the material through the synergistic response of at least two AIE components, thereby realizing non-destructive, real-time and quantitative monitoring of the repair process.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials, specifically including the following steps:

[0007] (1) Establishment of standard curve: The core material of the microcapsule flows out, and the healing agent undergoes a curing reaction under the action of a catalyst or initiator. During the curing reaction, the core material is tested at different time points using thermal analysis, chemical analysis, or mechanical property testing methods. The test results are converted into the degree of repair of the core material, and a standard curve of "degree of repair-time" is established. The degree of repair includes at least one of curing degree and mechanical property recovery rate.

[0008] At the same time point, the fluorescence spectrum of the core material was measured using optical detection methods, fluorescence characteristic parameters were extracted, and the fluorescence color of the core material was observed simultaneously. The fluorescence characteristic parameters included the trend of fluorescence spectrum change over time, fluorescence intensity at characteristic wavelengths, the ratio of fluorescence intensities at two or more characteristic wavelengths, and one or more of the fluorescence emission peak positions. Based on this, a standard spectrum of "fluorescence characteristic-time" and a standard colorimetric card of "fluorescence color-time" were established. Furthermore, using the time variable, standard spectra of "repair degree-fluorescence characteristic-time" and "repair degree-fluorescence color-time" were established.

[0009] (2) Monitoring of the actual damage repair process: After the self-healing material containing the microcapsules of step (1) is damaged, the core material flows out to the damaged area. Under the action of a catalyst or initiator, the healing agent undergoes a curing reaction. Timing starts from the damage trigger. At any monitoring time, the fluorescence characteristic parameters of the damaged area are measured using an optical detection method. By comparing the fluorescence characteristic parameters with the "repair degree-fluorescence characteristic-time" standard spectrum established in step (1), the equivalent repair degree (i.e., healing degree) reached by the current damaged area at the monitoring time can be obtained.

[0010] By observing the macroscopic fluorescence color of the damaged area and directly comparing it with the standard spectrum of "repair degree-fluorescence color-time", the degree of repair can be estimated and the repair stage reached can be quickly determined.

[0011] Based on the curing reaction triggering process, self-healing materials are classified into three types.

[0012] The first method involves the healing agent and catalyst or initiator flowing out of the core material and undergoing a curing reaction under the influence of external energy (such as light or heat) to achieve matrix repair. Correspondingly, the self-healing material includes a polymer matrix and a first microcapsule uniformly dispersed within the polymer matrix. The first microcapsule has a mass fraction of 5-25 wt.% in the self-healing material. The first microcapsule comprises a shell and a first core material encapsulated therein. The first core material includes a synergistic response system, a liquid healing agent, and a catalyst or initiator that triggers the curing of the healing agent. The total mass of the synergistic response system accounts for 0.01%-0.20% of the total mass of the liquid healing agent, and the catalyst or initiator accounts for 1%-4% of the total mass of the liquid healing agent. In this case, external energy (such as light or heat) is applied to the flowable first core material through specific wavelength ultraviolet light irradiation, heating, or microwave energy to trigger the curing reaction of the healing agent.

[0013] The second method involves the healing agent in the core material flowing out and reacting with the catalyst in the polymer matrix to achieve matrix repair. Correspondingly, the self-healing material includes a polymer matrix, second microcapsules uniformly dispersed in the polymer matrix, and a catalyst. The second microcapsules have a mass fraction of 5-25 wt.% in the self-healing material, and the catalyst has a mass fraction of 2.5-5 wt.%. The second microcapsule includes a shell and a second core material encapsulated therein. The second core material includes a synergistic response system and a liquid healing agent, with the total mass of the synergistic response system accounting for 0.01%-0.20% of the total mass of the liquid healing agent.

[0014] The third method involves a curing reaction between a healing agent flowing from one core material and a catalyst flowing from another core material to achieve matrix repair. Correspondingly, the self-healing material includes a polymer matrix and third and fourth microcapsules uniformly dispersed within the polymer matrix. The mass fraction of the third and fourth microcapsules in the self-healing material is 5-25 wt.%. The third microcapsule includes a shell and a third core material encapsulated therein. The third core material includes a liquid healing agent and a synergistic response system, with the total mass of the synergistic response system accounting for 0.01%-0.20% of the total mass of the liquid healing agent. The fourth microcapsule includes a shell and a fourth core material encapsulated therein, and the fourth core material includes a liquid catalyst.

[0015] Specifically, the synergistic response system includes at least two aggregation-induced emission (AIE) molecules with different emission wavelengths, and the mass ratio of any two AIE components is 1:2 to 1:60. AIE molecules are a class of special functional molecules that, in solution, dissipate excited-state energy through non-radiative transitions due to intense internal rotation / vibration, but exhibit strong fluorescence in confined environments (such as curing, aggregation, or high-viscosity environments) due to restricted intramolecular motion (RIM). Different AIE molecules within the synergistic response system are used to generate differentiated and synergistic optical responses to changes in the microenvironment (such as viscosity, polarity, free volume, and molecular mobility) during the curing process of the flowable core material. Their fluorescence characteristics (such as emission wavelength, intensity, lifetime, and peak shift) exhibit multi-stage, distinguishable, and regular changes with the curing process. Through signal superposition, competition, or complementarity, rich fluorescence spectral evolution and macroscopic color gradients are formed, providing a basis for multi-dimensional quantitative monitoring. Preferably, the synergistic response system consists of two AIE molecules with different emission wavelengths. More preferably, the two fluorescent molecules with different emission wavelengths, located in the blue and red light regions respectively, produce a composite color evolution that is easier to observe and distinguish through the superposition and competition of their fluorescence signals.

[0016] The AIE molecule includes tetraphenylethylene (TPE) and its derivatives, triphenylamine (TPA) derivatives, etc., wherein the TPE derivatives are tetraphenylethylene-dicyano (TPE-2CN), 4,4'-bis(1,2,2-triphenylvinyl)biphenyl (BTPE) or 1,1,2,2-tetra(4-methoxyphenyl)ethylene (TPE-4OMe), and the TPA derivatives are triphenylamine-phenanthreneimidazole (TPA-PPI), triphenylamine-benzothiadiazole (TPA-BT), and 2,3-bis[4-(diphenylamino)phenyl]fumaronitrile (BPF).

[0017] The liquid healing agent of this invention comprises a healing agent and a first auxiliary agent, with a mass ratio of 7:3-0. The healing agent is classified into epoxy resins, cyclic olefins, isocyanates, etc.; the epoxy resin healing agents include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic glycidyl ether epoxy resin, aliphatic epoxy resin, oligomeric epoxy glycidyl ether, etc.; the cyclic olefin healing agents include dicyclopentadiene, cyclopentadiene oligomers, etc.; the isocyanate healing agents include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), etc. The first auxiliary agent is used to dissolve the healing agent, or the healing agent and the synergistic response system, to assist in encapsulation or improve flow properties (e.g., as a solvent to promote dissolution and form a liquid solution). The specific selection depends on the physicochemical properties of the synergistic response system or the healing agent. When the healing agent itself is liquid and can dissolve AIE, the first auxiliary agent may not be added. For example, the healing agent is bisphenol A type epoxy resin, and the first auxiliary agent is ethyl phenylacetate.

[0018] Liquid catalysts consist of a catalyst and a second promoter, with a mass ratio of catalyst to promoter of 1:80-100. The second promoter is used to improve the catalyst's flow properties (e.g., as a solvent to promote dissolution and form a liquid solution), and its specific selection is based on the physicochemical properties of the catalyst. For example, if the catalyst is a second-generation Grubbs catalyst, the corresponding second promoter would be cyclohexylbenzene.

[0019] Catalysts are used to catalyze the curing reaction of the healing agent. The specific catalyst is selected based on the type of healing agent, and the specific triggering conditions are selected based on the characteristics of the healing agent. For example, if the healing agent is bisphenol A type epoxy resin, the corresponding catalyst (or photoinitiator) is triarylsulfonium hexafluorophosphate; if the healing agent is dicyclopentadiene (DCPD), the corresponding catalyst is a second-generation Grubbs catalyst.

[0020] The polymer matrix is ​​a thermosetting polymer or a thermoplastic polymer. Specifically, the polymer matrix includes thermosetting polymers such as epoxy resin, phenolic resin, urea-formaldehyde resin, and polydimethylsiloxane, or thermoplastic polymers such as polyamide and polystyrene.

[0021] The shell material can be selected from urea-formaldehyde resin, polyurethane, polymethyl methacrylate, silicon dioxide, etc.

[0022] Specifically, the thermal or chemical analysis methods include differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and thermogravimetric analysis (TGA). DSC is used to determine the exothermic enthalpy (or residual heat of reaction) of the core material's curing reaction. The degree of polymerization, or curing degree, is obtained by calculating the ratio of the residual heat of reaction to the total heat of reaction of the completely uncured sample. Fourier transform infrared spectroscopy is used to measure the characteristic absorption peak intensity of specific reactive functional groups (such as epoxy groups, carbon-carbon double bonds, or isocyanate groups) in the core material. The curing degree is obtained by calculating the rate of change of the characteristic functional group peak intensity relative to the internal standard peak intensity before and after the reaction. Raman spectroscopy is used to measure the Raman scattering peak intensity of characteristic chemical bonds (such as C=C double bonds or cyclic structures) in the core material. The curing degree is obtained by calculating the attenuation ratio of the characteristic peak intensity. Thermogravimetric analysis is used to measure the thermal decomposition behavior of the core material and the mass loss of volatile components. The curing degree is obtained by determining the mass percentage of volatile monomers or solvents that did not participate in the reaction.

[0023] Specifically, the mechanical property testing method in step (1) is an lap shear test, a tensile test, or a bending test. Specifically, the shear strength of the core material is determined by the lap shear test, and the ratio (or percentage) of the shear strength of the repaired sample to the shear strength of the original undamaged sample is used as the mechanical property recovery rate; the tensile strength of the core material is determined by the tensile test, and the ratio (or percentage) of the tensile strength of the repaired sample to the tensile strength of the original undamaged sample is used as the mechanical property recovery rate; the bending strength of the sample is determined by the bending test, and the ratio (or percentage) of the bending strength of the repaired sample to the bending strength of the original undamaged sample is used as the mechanical property recovery rate.

[0024] The optical detection method in step (1) includes measuring the fluorescence spectrum of the core material using a fluorescence spectrometer and an optical imaging system to obtain parameters such as the fluorescence spectrum, fluorescence emission peak wavelength, and fluorescence emission peak intensity ratio.

[0025] The preparation method of the self-healing material specifically includes the following steps:

[0026] (1) Preparation of core material oil phase: Weigh the core material raw materials, the core material including a first core material, a second core material or a third core material, and prepare a uniform and stable core material oil phase;

[0027] (2) Aqueous phase preparation: Dissolve urea, ammonium chloride, modifiers (such as resorcinol and melamine) and surfactants (such as ethylene-maleic anhydride copolymer (EMA) and sodium dodecyl sulfate (SDS)) in deionized water and adjust the pH value to 3.0-4.5 to form a stable aqueous phase.

[0028] (3) Emulsion preparation: Under mechanical stirring conditions (500-1200 rpm), the core material oil phase is slowly injected into the aqueous phase and emulsified for 10-30 minutes to form a stable oil-in-water emulsion. The droplet size of the emulsion is controlled at 50-150 μm.

[0029] (4) Interfacial polymerization and post-treatment: Add formaldehyde solution (mass fraction 37%) to the emulsion as a crosslinking agent, control the temperature to rise to 50-65 °C at a rate of 1-2 °C / min, and keep the reaction at this temperature for 3-6 hours; after the reaction, filter, wash repeatedly with deionized water (3-5 times), dry at room temperature (12-24 hours), and grade and sieve to obtain functional microcapsules with uniform particle size distribution (50-150 μm).

[0030] (5) Composite material molding: The microcapsules are uniformly mixed with the polymer matrix at a mass fraction of 5%-25%, and after vacuum degassing (vacuum degree -0.08~-0.1 MPa, time 15-30 minutes), the self-healing material is obtained by casting, molding or 3D printing.

[0031] Compared with the prior art, the present invention has the following beneficial effects.

[0032] (1) Innovative breakthrough in synergistic use of multiple AIE components: For the first time, at least two AIE components were clearly used to construct a synergistic response system, which has richer fluorescence response dimensions and higher signal discrimination compared to a single AIE molecule. Through multi-parameter synergistic calibration, the accuracy and stability of quantitative monitoring were significantly improved.

[0033] (2) Substantial methodological innovation: This invention goes beyond simple “damage fluorescence indication” and for the first time establishes a quantitative and calibrable mapping relationship between fluorescence signal parameters and the internal repair chemical state and macroscopic mechanical properties of materials. This invention elevates self-healing assessment from qualitative indication to quantitative characterization, providing a completely new data dimension for the accurate assessment of material service status and life prediction.

[0034] (3) Non-destructive and real-time monitoring process: The entire monitoring process is completely non-destructive, requiring no sampling or contact measurement. It can be carried out in real time and in situ while the material is in service, greatly improving the feasibility and convenience of engineering applications.

[0035] (4) Universality and flexibility of the monitoring mechanism: The core of the protection of this invention lies in the methodology of "quantitatively characterizing the repair process by utilizing changes in fluorescence signals", rather than a specific chemical system. By matching different types of AIE components, it can be adapted to a variety of healing chemical systems (epoxy, DCPD, etc.), and the system design is flexible.

[0036] (5) Practicality and Reliability: Microcapsule encapsulation ensures the long-term stability of the active components. Through examples, the evolution trend of the fluorescence signal and the recovery trend of mechanical properties are highly consistent, proving the effectiveness of this method as a reliability characterization tool and demonstrating broad industrial application prospects in safety-critical fields such as aerospace, new energy equipment, and flexible electronics. Attached Figure Description

[0037] Figure 1 is a schematic diagram of the damage and self-healing process of the self-healing material described in this invention.

[0038] Figure 2 shows the SEM morphology and fluorescence comparison images of the microcapsules prepared in Example 1 before and after solidification.

[0039] Figure 3 is a comparison of thermogravimetric analysis (TGA) between the microcapsules prepared in Example 1 of this invention and the pure liquid healing agent (core material).

[0040] Figure 4 shows the evolution of the fluorescence spectrum of the healing agent in Example 1 under different UV irradiation times.

[0041] Figure 5 is a curve showing the curing degree of the healing agent versus time in Example 1.

[0042] Figure 6 is a schematic diagram of the lap shear strength testing device.

[0043] Figure 7 shows the change in material shear strength with repair time in Example 1.

[0044] Figure 8 shows an actual observation photograph of the fluorescence color evolution of the damaged area of ​​the coating during the healing process.

[0045] Figure 9 This is a fluorescence spectrum evolution diagram of the healing agent during the curing process in Example 2. Detailed Implementation

[0046] The present invention will be further described in detail below through specific embodiments, but the scope of protection of the present invention is not limited thereto. Unless otherwise specified, the equipment and materials used in the following embodiments are commercially available.

[0047] Example 1: A method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials

[0048] This embodiment demonstrates the quantitative evolution of fluorescence color from red to blue using a specific combination of AIE molecules (BTPE and BPF), and correlates it with the curing degree of the epoxy healing agent and the recovery of material shear strength.

[0049] (1) Preparation of functional microcapsules:

[0050] (101) Preparation of oil phase: Bisphenol A type epoxy resin (EPON 813, 46.8 g), ethyl phenylacetate (12 g), photoinitiator triarylsulfonium hexafluorophosphate (1.2 g), AIE molecule 4,4'-bis(1,2,2-triphenylvinyl)-1,1'-biphenyl (BTPE, 48 mg) and 2,3-bis(4-N-phenyltetrastyryl)-2-butenedionitrile (BPF, 1.92 mg) were mixed evenly.

[0051] (102) Emulsion preparation: In a 500 mL beaker, urea (2.5 g), ammonium chloride (0.25 g), resorcinol (0.25 g), and surfactant ethylene-maleic anhydride copolymer (EMA, 0.5 g) were dissolved in deionized water (125 mL), and the pH of the aqueous phase was adjusted to 3.5 with sodium hydroxide solution. Under mechanical stirring at 800 rpm, the oil phase was slowly poured into the aqueous phase, and emulsification was carried out for 10 minutes to form a stable oil-in-water emulsion.

[0052] (103) Interfacial polymerization: A 37% formaldehyde solution (6.33 g) was added to the emulsion. The reaction system was placed in a 55 °C water bath, heated at a rate of 1 °C / min, and reacted for 4 hours. After the reaction, the product was filtered, washed repeatedly with deionized water to remove residual surfactants, and dried at room temperature. Finally, functional microcapsules with a particle size distribution of 75-125 μm were obtained by fractional sieving.

[0053] (2) Preparation of self-healing composite material: The above microcapsules are uniformly mixed with epoxy resin matrix at a mass fraction of 10 wt%, and after vacuum degassing, they are poured into a specific mold and cured.

[0054] (3) Morphology and stability

[0055] Figure 2 Scanning electron microscopy confirmed that the prepared microcapsules have a regular spherical morphology and a clear core-shell structure. Figure 3 Thermogravimetric analysis showed that the microcapsules exhibited excellent thermal stability. This result confirms that the microencapsulation technology successfully protected the internal healing agent, enabling it to withstand the high-temperature curing environment that may be involved in the composite material preparation process, thereby ensuring the effectiveness of the self-healing function.

[0056] (4) Establishment and validation of methods for measuring the degree of healing

[0057] (401) Establishment of the standard time-parameter curve library:

[0058] (a) The oil phase of the microcapsule core material was simultaneously monitored using a fluorescence spectrometer equipped with a 365 nm ultraviolet light source and an optical differential scanning calorimeter.

[0059] Curing Degree Standard Curve: The curing degree of the oil phase in step (101) at different irradiation times was tested using photopolymerization differential scanning calorimetry to obtain the "curing degree (degree of polymerization) - time" standard curve (e.g., ...). Figure 5 The degree of curing (degree of polymerization) α is calculated using the following formula:

[0060] α=ΔH t / ΔH×100%

[0061] Where, ΔH t : The cumulative heat released up to time t;

[0062] ΔH: The total heat release that should occur upon complete curing.

[0063] Fluorescence characteristic standard spectrum: The fluorescence spectra of the oil phase in step (101) under different irradiation times are collected, which are the "fluorescence characteristic-time" standard spectra (e.g. Figure 4 Simultaneously, by recording the color of the sample under ultraviolet light at each time point, a standard colorimetric card of "fluorescence color-time" can be created. Figure 5 (At the ordinate).

[0064] Furthermore, by using the time variable, standard spectra for "curing degree-fluorescence characteristics-time" and "curing degree-fluorescence color-time" are established. Figure 5 ).

[0065] (b) Mechanical property recovery curve: such as Figure 6 As shown, a standard lap shear test specimen was prepared by placing microcapsule samples encapsulated with healing agent between two glass slides. The microcapsules were then squeezed in the lap area to release the healing agent. The microcapsules were irradiated with a 365 nm ultraviolet light source. While applying a shear load and promoting the curing of the healing agent, the lap shear strength of the sample was measured at regular intervals, and the fluorescence peak positions in the same region were recorded using a fluorescence spectrometer.

[0066] Mechanical property recovery rate standard curve: The shear strength of microcapsules under different irradiation times was tested to obtain the "shear strength recovery rate - time" standard curve (e.g.) Figure 7 This is the standard curve of "mechanical property recovery rate - time".

[0067] Fluorescence characteristic standard spectrum: The fluorescence spectra of microcapsules at different irradiation times are collected, which are the "fluorescence characteristic-time" standard spectrum. At the same time, the color of the sample under ultraviolet light at each time point is recorded.

[0068] Furthermore, by using the time variable, standard spectra for "mechanical property recovery rate - fluorescence characteristics - time" and "mechanical property recovery rate - fluorescence color - time" were established. Figure 7 ).

[0069] Figure 7 The plotted "shear strength recovery rate-time" curve and Figure 5 The "curing degree-time" curve showed a highly consistent trend. As the fluorescence color shifted from green-blue to blue, the interfacial shear strength of the material gradually increased from a peeled state, eventually recovering to over 85% of its original strength. This change in strength quantitatively reflects the degree of curing and repair of the interface.

[0070] Mechanism Explanation: In this specific system, the programmed evolution of fluorescence color (red → green → blue) is the result of multiple mechanisms working together: a) BPF molecules are sensitive to environmental viscosity / polarity, exhibiting red fluorescence in the early liquid state; b) As curing progresses, the system viscosity increases, restricting the intramolecular rotation of BTPE, and its blue fluorescence efficiency increases sharply; c) Due to the large amount of BTPE added and its high solid-state luminescence efficiency, its high-intensity blue light eventually becomes dominant. This process indicates that the fluorescence signal (represented here as color / spectrum) is highly responsive to changes in the microenvironment and has a quantitative correlation with the degree of polymerization.

[0071] (402) Real-time monitoring of actual damage repair:

[0072] For damaged samples, irradiation was performed under the same 365 nm ultraviolet light, and timing was started. At any monitoring time, the fluorescence spectrum of the damaged area was acquired, and the fluorescence color of the damaged area was observed simultaneously. Figure 8 The fluorescence spectrum is compared with the standard spectrum of "curing degree-fluorescence feature-time" and "mechanical property recovery rate-fluorescence feature-time" established in step (401) to find the corresponding curing degree and mechanical property recovery rate. These two parameters are used to characterize the degree of healing achieved by the current damaged area at the monitoring time.

[0073] Simplified assessment: The degree of curing and the rate of recovery of mechanical properties can also be quickly estimated by observing the color of the damaged area and directly comparing it with the standard spectra of "curing degree-fluorescence color-time" and "mechanical property recovery rate-fluorescence color-time". This allows for a rough estimation of the repair stage (e.g., early, middle, or late stage). For example, for the self-healing material prepared in this embodiment, green fluorescence indicates the middle stage of curing, blue fluorescence indicates the middle to late stage of curing, and dark blue fluorescence indicates the late stage of curing.

[0074] The fluorescence signal monitored by this method can serve as a reliable, non-destructive indicator of the degree of recovery of the internal mechanical properties of a material. The repair effect can be assessed in real time simply by monitoring the evolution of the fluorescence signal.

[0075] Example 2: A method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials

[0076] Except for the matrix material in steps (101) and (2), all other steps in this embodiment are the same as in embodiment 1.

[0077] (1) Preparation of microcapsules:

[0078] (101) First, the healing agent dicyclopentadiene (57 g), the adjuvant ethylidene norbornene (3 g), and TPE (96 mg) and BPF (1.92 mg) as aggregation-induced emission (AIE) molecules were thoroughly mixed to obtain a uniform oil phase.

[0079] (102) and (103) are the same as in Example 1.

[0080] (2) Preparation of self-healing material: 10 wt% microcapsules and 2.5 wt% second-generation Grubbs catalyst were uniformly mixed with polydimethylsiloxane (PDMS) matrix, and after vacuum degassing, they were poured into a specific mold and cured.

[0081] (3) Method for determining the degree of healing (same as in Example 1)

[0082] This embodiment also observed a regular change in fluorescence signal with the DCPD polymerization reaction (e.g. Figure 9 (As shown).

[0083] The method for quantitative monitoring of the repair process based on fluorescence spectroscopy described in this invention is universally applicable to different self-healing chemical systems. By matching a suitable combination of fluorescently responsive molecules, a quantitative correlation between optical signals and mechanical states can be established, enabling non-destructive, real-time monitoring of the repair process.

[0084] The above embodiments fully verify the feasibility, effectiveness, and universality of the core method of the present invention, providing a solid technical foundation for realizing the "self-diagnosis" function of smart materials.

[0085] Compared to traditional technologies, the core advantage of this invention lies in constructing and validating a universal monitoring methodology based on quantitative mapping of the internal state of materials using fluorescence signals. Existing technologies typically only achieve static color marking of damage points, while this invention, by constructing a correlation model of "fluorescence parameters-chemical state-mechanical properties," achieves "visualization" and "quantitative" tracking of the dynamic repair process. This methodological improvement enables smart materials to truly possess "self-diagnostic" capabilities, significantly enhancing their reliability and practical application prospects in safety-critical fields such as aerospace and new energy.

Claims

1. A method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials, characterized in that, Includes the following steps: (1) Establishment of standard curve: The core material of the microcapsule flows out and the healing agent undergoes a curing reaction under the action of a catalyst or initiator. During the curing reaction, the core material is tested at different time points using thermal analysis, chemical analysis or mechanical property testing methods. The test results are converted into the degree of repair of the core material, and a standard curve of "degree of repair-time" is established. The degree of repair includes at least one of curing degree and mechanical property recovery rate. At the same time point, the fluorescence spectrum of the core material is measured using optical detection methods, fluorescence characteristic parameters are extracted, and the fluorescence color of the core material is observed. The fluorescence characteristic parameters include the trend of fluorescence spectrum change over time, fluorescence intensity of characteristic wavelengths, fluorescence intensity ratio of two or more characteristic wavelengths, and one or more of fluorescence emission peak positions. Thus, a standard spectrum of "fluorescence characteristic-time" and a standard colorimetric card of "fluorescence color-time" are established. Furthermore, by using the time variable, a standard spectrum of "repair degree-fluorescence characteristic-time" and a standard spectrum of "repair degree-fluorescence color-time" are established. (2) Monitoring of actual damage repair process: After the self-healing material containing the microcapsules in step (1) is damaged, the core material flows out to the damaged area. Under the action of a catalyst or initiator, the healing agent undergoes a curing reaction. Timing starts from the damage trigger. At any monitoring time, the fluorescence characteristic parameters of the damaged area are measured by optical detection method. The fluorescence characteristic parameters are compared with the "repair degree-fluorescence characteristic-time" standard spectrum established in step (1) to obtain the equivalent repair degree reached by the current damaged area at the monitoring time. By observing the macroscopic fluorescence color of the damaged area and directly comparing it with the standard spectrum of "repair degree-fluorescence color-time", the degree of repair can be estimated and the repair stage reached can be quickly determined.

2. The method for real-time visualization and autonomous quantitative assessment of the self-healing material repair process according to claim 1, characterized in that, Step (1) After the healing agent and catalyst or initiator in the core material flow out, they undergo a curing reaction under the action of external energy to achieve matrix repair. Correspondingly, the self-healing material includes a polymer matrix and a first microcapsule uniformly dispersed in the polymer matrix. The mass fraction of the first microcapsule in the self-healing material is 5-25 wt.%. The first microcapsule includes a shell and a first core material encapsulated therein. The first core material includes a synergistic response system, a liquid healing agent, and a catalyst or initiator that can trigger the curing of the healing agent. The total mass of the synergistic response system accounts for 0.01%-0.20% of the total mass of the liquid healing agent, and the catalyst or initiator accounts for 1%-4% of the total mass of the liquid healing agent.

3. The method for real-time visualization and autonomous quantitative assessment of the self-healing material repair process according to claim 1, characterized in that, Step (1) After the healing agent in the core material flows out, it undergoes a curing reaction with the catalyst in the polymer matrix to achieve matrix repair. Correspondingly, the self-healing material includes a polymer matrix, a second microcapsule uniformly dispersed in the polymer matrix, and a catalyst. The mass fraction of the second microcapsule in the self-healing material is 5-25 wt.%, and the mass fraction of the catalyst in the self-healing material is 2.5-5 wt.%. The second microcapsule includes a shell and a second core material encapsulated therein. The second core material includes a synergistic response system and a liquid healing agent. The total mass of the synergistic response system accounts for 0.01%-0.20% of the total mass of the liquid healing agent.

4. The method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials according to claim 1, characterized in that, Step (1) A healing agent flowing out of one core material undergoes a curing reaction with a catalyst flowing out of another core material to achieve matrix repair. Correspondingly, the self-healing material includes a polymer matrix and a third microcapsule and a fourth microcapsule uniformly dispersed in the polymer matrix. The mass fraction of the third microcapsule and the fourth microcapsule in the self-healing material is 5-25 wt.%. The third microcapsule includes a shell and a third core material encapsulated therein. The third core material includes a liquid healing agent and a synergistic response system. The total mass of the synergistic response system accounts for 0.01%-0.20% of the total mass of the liquid healing agent. The fourth microcapsule includes a shell and a fourth core material encapsulated therein. The fourth core material includes a liquid catalyst.

5. The method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials according to any one of claims 2-4, characterized in that, The synergistic response system includes at least two AIE molecules with different emission wavelengths.

6. The method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials according to claim 5, characterized in that, The AIE molecule includes TPE and its derivatives, and TPA derivatives, wherein the TPE derivative is tetraphenylethylene-dicyano, 4,4'-bis(1,2,2-triphenylvinyl)biphenyl or 1,1,2,2-tetra(4-methoxyphenyl)ethylene, and the TPA derivative is triphenylamine-phenimazole, triphenylamine-benzothiadiazole, or 2,3-bis[4-(diphenylamino)phenyl]fumaronitrile.

7. The method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials according to any one of claims 2-4, characterized in that, The liquid healing agent includes a healing agent and a first auxiliary agent, with a mass ratio of 7:3-0. The healing agent is classified into epoxy resin, cyclic olefin, and isocyanate types.

8. The method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials according to any one of claims 2-4, characterized in that, The liquid catalyst includes a catalyst and a second promoter, with a mass ratio of 1:80-100.

9. The method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials according to any one of claims 2-4, characterized in that, The polymer matrix is ​​a thermosetting polymer or a thermoplastic polymer; the shell material can be selected from urea-formaldehyde resin, polyurethane, polymethyl methacrylate, and silicon dioxide.

10. The method for real-time visualization and autonomous quantitative assessment of the repair process of self-healing materials according to claim 1, characterized in that, The thermal or chemical analysis methods are differential scanning calorimetry, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. Specifically, the mechanical performance testing method described in step (1) is an overlap shear test, a tensile test, or a bending test; The optical detection method in step (1) includes measuring the fluorescence spectrum of the core material using a fluorescence spectrometer and an optical imaging system to obtain parameters such as fluorescence spectrum, fluorescence emission peak wavelength, and fluorescence emission peak intensity ratio.

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