A self-healing crystal material and its preparation method

Abstract

This invention relates to the field of crystal material technology, and provides a self-healing crystal material and its preparation method, wherein the structural formula of the material is shown in Formula 1 or Formula 2; wherein, R 1 R 2 R 3 R 4 Taken from H, CH3, C2H5, OCH3, and Br respectively; R 5 and R 6 The materials are derived from N(CH3)2 and N(C2H5)2, respectively. The self-healing crystal material provided by this invention has a reasonable structural design and can achieve rapid and efficient self-healing behavior in low-temperature environments without relying on high temperatures or external energy. It also has high repeatability, excellent environmental adaptability, and potential industrial feasibility, and can be widely used in polar engineering, low-temperature electronic devices, cold chain logistics packaging, and low-temperature sensing systems.

Description

Technical Field

[0001] This invention belongs to the field of crystal material technology, and in particular relates to a crystal material with self-healing ability and its preparation method. Background Technology

[0002] Self-healing materials are a class of smart materials that can autonomously repair damaged areas and restore functional properties after being subjected to external damage through physical or chemical response mechanisms within their internal structure. In recent years, with the rapid development of applications such as flexible electronics, wearable devices, structural health monitoring, and advanced coatings, self-healing materials have attracted widespread attention due to their characteristics of extending service life, reducing maintenance costs, and improving material reliability.

[0003] Currently, mainstream self-healing materials mainly include several types: microcapsule-type self-healing materials pre-embed microcapsules containing repair agents, which release repair monomers when the material breaks and solidify under the action of a catalyst to complete self-healing; dynamic covalent bond systems utilize external stimuli such as temperature and light to activate reversible covalent bonds in the material, such as Diels-Alder reactions, transesterification, or disulfide bonds, to reconnect the crack surfaces; non-covalent interaction systems rely on reconfigurable weak forces such as hydrogen bonds, metal coordination, and π-π stacking to quickly restore the structural integrity of the material after damage; phase change self-healing materials induce controllable molecular rearrangement within the material through thermally or photo-induced phase transitions, assisting in the crack repair process.

[0004] Existing self-healing materials exhibit good self-healing capabilities at room temperature or medium-high temperatures, but they also generally suffer from some drawbacks, especially at low temperatures (such as below 0°C): First, low temperatures significantly limit the thermal mobility of molecular chain segments, preventing sufficient molecular rearrangement and migration within the material, making it difficult for fractured interfaces to effectively connect and repair. Second, self-healing mechanisms that rely on thermal activation or catalytic reactions experience a significant decrease in reaction rate at low temperatures, resulting in a significant reduction in self-healing efficiency or even complete failure. Furthermore, many materials require specific environments such as high temperatures, ultraviolet radiation, or humid heat to activate the repair process, making them unsuitable for extreme environments with low temperatures, dryness, or insufficient light. At the same time, while increasing intermolecular forces can enhance the structural stability of materials, it often inhibits self-healing capabilities, creating a contradiction between repair performance and material strength. Finally, in low-temperature applications such as cold chain transportation, polar exploration, and aerospace, there is a lack of practical materials that can serve for extended periods and possess self-healing capabilities, greatly limiting the promotion and application of smart materials in extreme environments. Summary of the Invention

[0005] The purpose of this invention is to provide a crystal material with self-healing capabilities, thereby addressing the problems mentioned in the background section.

[0006] The present invention is implemented as follows: a crystalline material with self-healing ability, the structural formula of which is shown in Formula 1 or Formula 2:

[0007] ;

[0008] Formula 1

[0009] ;

[0010] Formula 2

[0011] Among them, R 1 R 2 R 3 R 4 Taken from H, CH3, C2H5, OCH3, and Br, respectively;

[0012] R 5 and R 6 They were taken from N(CH3)2 and N(C2H5)2, respectively.

[0013] Preferably, the material is any of the following compounds:

[0014] , ,

[0015] , ,

[0016] , ,

[0017] , .

[0018] Another objective of this invention is to provide a method for preparing a self-healing crystal material, comprising the following steps:

[0019] Terephthalic acid nitrile and the reactants were added to ethanol, followed by the addition of sodium hydroxide. After stirring, the mixture was filtered to obtain a solid crude product. The solid crude product was then purified to obtain the target compound.

[0020] The target compound was dissolved in a good solvent, and a poor solvent was added dropwise on the top layer of the good solvent. After standing for several days, a crystalline material was obtained.

[0021] The reactant is one of 4-(diphenylamino)benzaldehyde, 4-((4-bromophenyl)(phenyl)amino)benzaldehyde, 4-di-p-toluidinebenzaldehyde, 4-di-p-ethylphenylaminobenzaldehyde, 4-[bis(4-methoxyphenyl)amino]benzaldehyde, 4-(bis(4-bromophenyl)amino)benzaldehyde, N,N-dimethyl-4-aminobenzaldehyde, and N,N-diethyl-4-aminobenzaldehyde.

[0022] Preferably, the step of filtering after stirring is specifically to filter after stirring at room temperature for 5-7 hours.

[0023] Preferably, the step of purifying the crude solid product specifically involves purification by column chromatography using dichloromethane as the eluent.

[0024] Preferably, the good solvent is dichloromethane, and the bad solvent is ethanol.

[0025] Another objective of this invention is to provide an application of a self-healing crystal material in optical devices, flexible electronics, and repairable organic materials.

[0026] The present invention provides a self-healing crystal material with a reasonable structural design, which can achieve rapid and efficient self-healing behavior in low-temperature environments (such as -190°C or even lower) without relying on high temperature or external energy. It not only has excellent low-temperature self-healing ability, but also has high repeatability, excellent environmental adaptability and potential industrial feasibility. It can be widely used in polar engineering, low-temperature electronic devices, cold chain logistics packaging and low-temperature sensing systems, thereby effectively overcoming the technical bottleneck of insufficient self-healing performance of existing technologies under low-temperature conditions. Attached Figure Description

[0027] Figure 1 This describes the stepwise self-healing process of the crystal material prepared in Example 1 of the present invention.

[0028] Figure 2 This describes the external force-assisted healing process of the crystal material prepared in Example 1 of the present invention.

[0029] Figure 3 This describes the self-healing process of the crystal material prepared in Example 1 of the present invention under high temperature and low temperature environments;

[0030] Figure 4 This is a schematic diagram of the recovery of the light transmission capability of the crystal material prepared in Example 1 of the present invention (a is before fracture, b is after fracture, c is after self-healing). Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] A self-healing crystalline material, the preparation method of which includes the following steps:

[0033] (1) Synthesis of small organic molecule compound 1, the synthetic route is shown below:

[0034] ;

[0035] Terephthalic acid nitrile (1 eq) and 4-(diphenylamino)benzaldehyde (2 eq) were added to ethanol, and sodium hydroxide was added. After stirring at room temperature for 6 hours, the mixture was filtered to obtain a solid crude product. The solid crude product was purified by column chromatography using dichloromethane as the eluent to obtain the target compound.

[0036] (2) Crystal growth: Dissolve the target compound in a good solvent, add a poor solvent on top of the good solvent, let stand, and obtain the crystal material after several days.

[0037] A self-healing crystalline material, the preparation method of which includes the following steps:

[0038] (1) Synthesize organic small molecule compound 2. The synthetic route is shown below:

[0039] ;

[0040] Terephthalic acid nitrile (1 eq) and 4-((4-bromophenyl)(phenyl)amino)benzaldehyde (2 eq) were added to ethanol, and sodium hydroxide was added. After stirring at room temperature for 6 hours, the mixture was filtered to obtain a solid crude product. The solid crude product was purified by column chromatography using dichloromethane as the eluent to obtain the target compound.

[0041] (2) Crystal growth: Dissolve the target compound in a good solvent, add a poor solvent on top of the good solvent, let stand, and obtain the crystal material after several days.

[0042] A self-healing crystalline material, the preparation method of which includes the following steps:

[0043] (1) Synthesize organic small molecule compound 3. The synthetic route is shown below:

[0044] ;

[0045] Terephthalic acid nitrile (1 eq) and 4-di-p-toluidine benzaldehyde (2 eq) were added to ethanol, and sodium hydroxide was added. After stirring at room temperature for 6 hours, the mixture was filtered to obtain a solid crude product. The solid crude product was purified by column chromatography using dichloromethane as the eluent to obtain the target compound.

[0046] (2) Crystal growth: Dissolve the target compound in a good solvent, add a poor solvent on top of the good solvent, let stand, and obtain the crystal material after several days.

[0047] A self-healing crystalline material, the preparation method of which includes the following steps:

[0048] (1) Synthesize organic small molecule compound 4. The synthetic route is shown below:

[0049] ;

[0050] Terephthalic acid nitrile (1 eq) and 4-di-p-ethylaniline benzaldehyde (2 eq) were added to ethanol, and sodium hydroxide was added. After stirring at room temperature for 6 hours, the mixture was filtered to obtain a solid crude product. The solid crude product was purified by column chromatography using dichloromethane as the eluent to obtain the target compound.

[0051] (2) Crystal growth: Dissolve the target compound in a good solvent, add a poor solvent on top of the good solvent, let stand, and obtain the crystal material after several days.

[0052] A self-healing crystalline material, the preparation method of which includes the following steps:

[0053] (1) Synthesize organic small molecule compound 5. The synthetic route is shown below:

[0054] ;

[0055] Terephthalic acid nitrile (1 eq) and 4-[bis(4-methoxyphenyl)amino]benzaldehyde (2 eq) were added to ethanol, and sodium hydroxide was added. After stirring at room temperature for 6 hours, the mixture was filtered to obtain a solid crude product. The target compound was dissolved in a good solvent, and a poor solvent was added dropwise to the top layer of the good solvent. After standing for several days, crystalline material was obtained.

[0056] (2) Crystal growth: Dissolve the target compound in an organic solvent, and slowly add a poor solvent on the top layer of the organic solvent. After standing for several days, the crystal material is obtained.

[0057] A self-healing crystalline material, the preparation method of which includes the following steps:

[0058] (1) Synthesize the small organic molecule compound 6. The synthetic route is shown below:

[0059] ;

[0060] Terephthalic acid nitrile (1 eq) and 4-(bis(4-bromophenyl)amino)benzaldehyde (2 eq) were added to ethanol, and sodium hydroxide was added. After stirring at room temperature for 6 hours, the mixture was filtered to obtain a solid crude product. The solid crude product was purified by column chromatography using dichloromethane as the eluent to obtain the target compound.

[0061] (2) Crystal growth: Dissolve the target compound in a good solvent, add a poor solvent on top of the good solvent, let stand, and obtain the crystal material after several days.

[0062] A self-healing crystalline material, the preparation method of which includes the following steps:

[0063] (1) Synthesize the small organic molecule compound 7. The synthetic route is shown below:

[0064] ;

[0065] Terephthalic acid nitrile (1 eq) and N,N-dimethyl-4-aminobenzaldehyde (2 eq) were added to ethanol, and sodium hydroxide was added. After stirring at room temperature for 6 hours, the mixture was filtered to obtain a solid crude product. The solid crude product was purified by column chromatography using dichloromethane as the eluent to obtain the target compound.

[0066] (2) Crystal growth: Dissolve the target compound in a good solvent, add a poor solvent on top of the good solvent, let stand, and obtain the crystal material after several days.

[0067] A self-healing crystalline material, the preparation method of which includes the following steps:

[0068] (1) Synthesize organic small molecule compound 8. The synthetic route is shown below:

[0069] ;

[0070] Terephthalic acid nitrile (1 eq) and N,N-diethyl-4-aminobenzaldehyde (2 eq) were added to ethanol, and sodium hydroxide was added. After stirring at room temperature for 6 hours, the mixture was filtered to obtain a solid crude product. The solid crude product was purified by column chromatography using dichloromethane as the eluent to obtain the target compound.

[0071] (2) Crystal growth: Dissolve the target compound in a good solvent, add a poor solvent on top of the good solvent, let stand, and obtain the crystal material after several days.

[0072] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0073] Example 1: A self-healing crystalline material (2Z,2′Z)-2,2′-(1,4-phenylene)bis[3-(4-(diphenylamino)phenyl)acrylonitrile] (PBDPA) is prepared by the following steps:

[0074] (1) Synthesis of small organic molecule compound 1, the synthetic route is shown below:

[0075] ;

[0076] Terephthalic acid nitrile (1 eq) and 4-(diphenylamino)benzaldehyde (2 eq) were added to ethanol, and sodium hydroxide was added. After stirring at room temperature for 6 hours, the mixture was filtered to obtain a solid crude product. The solid crude product was purified by column chromatography using dichloromethane as the eluent to obtain the target compound.

[0077] (2) Crystal growth: The target compound was dissolved in dichloromethane, and ethanol was slowly added dropwise to the upper layer of the dichloromethane solution. After standing, solvent-solvent diffusion crystallization was carried out. After several days, transparent orange plate-shaped crystals were obtained. The crystals showed visible light absorption at a wavelength of 420 nm and emitted strong yellow fluorescence at 570 nm, exhibiting excellent optical properties.

[0078] The performance of the PBDPA crystals prepared in Example 1 was analyzed, and the following results were obtained:

[0079] Self-healing behaviors and mechanisms:

[0080] Crystals can heal themselves after mechanical damage without external intervention, such as Figure 1 As shown, the self-healing behavior depends on the crack spacing and the degree of interface alignment. When the crack surfaces are close and aligned, the cracks close instantly after the external force is removed. When the spacing is moderate, the crystals gradually connect and repair, exhibiting a progressive healing characteristic. The healing process is characterized by a zipper-like closure: local contact initiates overall repair, and finally, the interface overlaps.

[0081] External force-assisted healing:

[0082] When the crack distance is large or the interface misalignment is significant (such as the formation of steps or fractures), the crystal cannot heal spontaneously. In this case, external force can be used to rebuild the contact and restore the healing function. Figure 2 As shown, applying a longitudinal force along the (001) crystal plane can close the crack, and applying a transverse force to the misaligned structure can achieve interface alignment. After healing, the structure of most areas of the crystal is continuous, with slight residual cracks in some areas, which may be due to the destruction of the bottom structure.

[0083] Temperature adaptability:

[0084] The crystal was heated on a temperature-controlled stage and observed under a microscope, such as... Figure 3 As shown, the crystal can still self-heal when the temperature reaches 150℃ (423 K), indicating that the process is feasible at high temperatures. Another crystal was placed in liquid nitrogen at about -196℃ (77 K), and self-healing was also observed at low temperatures. Optical microscopy showed that five of the six main cracks were completely healed, and the remaining crack was partially healed.

[0085] Self-healing capability can be used to restore optical transmission performance:

[0086] like Figure 4 As shown, the crystal exhibits a strong luminescence response under 365 nm laser excitation, with an undamaged luminescence intensity of 4.7127 × 10⁻⁶. 4 After the crystal fractured, its light transmittance dropped to 34% of its original value. However, after self-healing under slight pressure at room temperature, the light transmittance recovered to 99% of its initial value (4.6548 × 10⁻⁶). 4 Further optical loss testing showed that the optical attenuation coefficient of the crystal was 0.156 dB / mm before fracture, increased to 0.427 dB / mm after fracture, and recovered to 0.163 dB / mm after self-healing, close to the initial state; this confirmed the crystal's structural self-healing ability in maintaining high optical transmission performance, and is particularly suitable for the construction of flexible optoelectronic devices, self-healing optical waveguides and high-stability organic optical components.

[0087] In summary, the embodiments of this invention propose a series of organic molecules with excellent self-healing capabilities and optical properties. These molecules, through the construction of a rigid conjugated framework and multi-level weak interactions, endow them with unique molecular alignment and interface recognition capabilities in the crystalline state, enabling the crystal to automatically heal after damage and efficiently restore its optical transmittance. Specifically:

[0088] Highly efficient self-healing ability: After mechanical damage, the crystalline state of this organic molecule can achieve rapid or gradual self-healing at room temperature without complex external stimuli, exhibiting excellent structural self-recovery performance.

[0089] Optical performance is almost completely restored: before and after self-healing, the transmittance of the crystal can be restored to 99% of the original value, and the optical loss coefficient is restored from 0.427 dB / mm after the fracture to 0.163 dB / mm, close to the initial 0.156 dB / mm, indicating that the optical function is almost undamaged.

[0090] Self-healing under low temperature conditions: It still exhibits obvious self-healing behavior in extreme low temperature environments as low as 77 K, breaking through the dependence of traditional self-healing materials on molecular migration and high temperature conditions, and significantly broadening its application environment.

[0091] Integrated structural-functional repair: The self-healing process not only repairs crystal structure cracks, but also simultaneously restores its optical transmission performance, achieving dual repair of structural integrity and functional performance.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. Use of a crystalline material having self-healing ability in a repairable organic material, characterized in that, The crystal material with self-healing ability is compound 1, and a structural formula is as follows: 。 2. Use of a crystalline material having self-healing ability according to claim 1 in a repairable organic material, characterized in that, The preparation method of the crystal material with self-healing ability comprises the following steps: The p-phenylenediacetonitrile and a reactant are respectively added into ethanol, and then sodium hydroxide is added, and after stirring, the solid crude product is obtained, and the solid crude product is purified to obtain the target compound; The target compound is dissolved in a good solvent, and a poor solvent is added dropwise on the upper layer of the good solvent, and the crystal material is obtained after standing for several days; The reactant is 4-(diphenylamine) benzaldehyde.

3. Use of a crystalline material having self-healing ability according to claim 2 in a repairable organic material, characterized in that, The step of stirring and filtering is specifically filtering after stirring for 5-7 hours at room temperature.

4. Use of a crystalline material having self-healing ability according to claim 2 in a repairable organic material, characterized in that, The step of purifying the solid crude product is specifically purifying by column chromatography and using dichloromethane as an eluent.

5. Use of the crystalline material with self-healing ability according to claim 2 in a repairable organic material, characterized in that, The good solvent is dichloromethane, and the poor solvent is ethanol.

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