High-strength low-temperature-resistant recyclable adhesive and preparation method thereof

Abstract

The invention relates to the technical field of low-temperature adhesive materials, and discloses a high-strength low-temperature-resistant recoverable adhesive and a preparation method thereof.The method comprises the steps that DL-alpha-lipoic acid and N, N '-carbonyldiimidazole are dissolved in a polar organic solvent and then react with ethylenediamine, and a comonomer SNH is obtained through purification; the preparation method comprises the following steps: dissolving a benzo-21-crown-7 derivative B21C7-N and 1, 2-dithienyl-3-pentanoic acid succinimide ester in acetone, adding triethylamine, carrying out a reaction, and purifying to obtain a comonomer SC; and uniformly mixing the comonomers SC and SNH, and polymerizing under an ultraviolet light source to obtain the adhesive. The molecular structure is reasonably designed from the chemical angle, the adhesive is synthesized in one step in the room temperature environment through lipoic acid photo-initiation polymerization, and the adhesive has excellent room temperature scene adhesion strength, has the best adhesion strength at about 25 DEG C, meets the conventional use requirement, also has excellent liquid nitrogen temperature adhesion strength, and has the good application prospect. And the method has the characteristics of excellent reusability and complete closed-loop recovery.

Description

Technical Field

[0001] This invention relates to the field of low-temperature adhesive materials technology, specifically to a high-strength, low-temperature resistant, recyclable adhesive and its preparation method. Background Technology

[0002] As a key material for achieving lightweight structures, multifunctional integration, and device miniaturization, adhesives play a vital role in promoting the research and development of high-performance materials and intelligent manufacturing. With human activities expanding into extreme environments such as polar regions and deep space, adhesive materials are facing unprecedented performance challenges. These materials not only need to maintain mechanical integrity and interfacial stability at low temperatures, but also need to meet increasingly stringent requirements for recyclability, environmental compatibility, and sustainability. Therefore, developing high-performance adhesives that combine high adhesive strength, wide temperature range tolerance, and closed-loop recyclability has significant scientific and engineering value.

[0003] Traditional structural adhesives (such as epoxy resins and acrylate systems) possess excellent room-temperature performance, but their removal and recycling without damaging the substrate material are extremely difficult. Commercially available low-temperature adhesives (such as polyethersulfone, ethylene-vinyl acetate copolymers, polyamides, and polyurethanes) often exhibit stress cracking, interfacial adhesion failure, and debonding when temperatures drop to approximately -50°C. These performance degradation phenomena stem from two core factors: first, polymers shrink in volume at low temperatures, and the movement of frozen molecular chains is restricted, preventing the release of internal stress, ultimately leading to material embrittlement and stress cracking; second, under low-temperature conditions, residual free water molecules in the adhesive matrix easily form ice crystal clusters, which become stress concentration points, severely impairing interfacial adhesion. These limitations reveal an essential contradiction in polymer molecular design: rigid molecular structures suitable for room-temperature bonding tend to exacerbate material embrittlement at low temperatures; while flexible molecular chains that improve low-temperature resistance often sacrifice the material's load-bearing capacity and adhesive durability. Therefore, developing adhesives that combine high bonding strength, recyclability, and stable service performance over a wide temperature range remains a highly challenging task. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of stress cracking, interfacial adhesion failure and debonding that occur in traditional adhesive materials under extremely low temperature conditions, and to provide a method for preparing a high-strength, low-temperature resistant, recyclable adhesive. The adhesive obtained by this method is green, environmentally friendly, reusable, and completely recyclable.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for preparing a high-strength, low-temperature resistant, recyclable adhesive, comprising the following steps:

[0006] S1. DL-α-lipoic acid and N,N'-carbonyldiimidazole were dissolved in a polar organic solvent and then added dropwise to a dichloromethane solution of ethylenediamine to carry out the reaction. After the reaction was completed, the reaction solution was extracted with water, the organic phases were combined and concentrated, and then purified by silica gel column chromatography to obtain the comonomer SNH with the following structure:

[0007] ;

[0008] S2. Potassium carbonate and potassium fluoroborate were dissolved in anhydrous acetonitrile, and hexaethylene glycol di-p-toluenesulfonate (HEDP) and N-(tert-butoxycarbonyl)dopamine (DA-Boc) were added. The mixture was heated under reflux at 70-90°C. After the reaction was completed, the mixture was cooled to room temperature and filtered. The concentrated solution was extracted with saturated sodium chloride solution. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain the crude product. The crude product was then purified by silica gel column chromatography to obtain the benzo-21-crown-7 derivative B21C7-boc with the following structure:

[0009] ;

[0010] S3. The benzo-21-crown-7 derivative B21C7-boc was dissolved in dichloromethane, and trifluoroacetic acid (TFA) was added to carry out the reaction. After the reaction was completed, the mixture was concentrated under reduced pressure to obtain the benzo-21-crown-7 derivative B21C7-N with the following structure:

[0011] ;

[0012] S4. The benzo-21-crown-7 derivative B21C7-N and succinimide 1,2-dithiapentane-3-pentanoic acid were dissolved in acetone, and triethylamine was added to react. After the reaction was completed, the mixture was filtered and concentrated under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography to obtain the comonomer SC with the following structure:

[0013] ;

[0014] S5. Mix the comonomers SC and SNH at a molar ratio of 1:0.5~2.5 until homogeneous, and perform photo-initiated polymerization under an ultraviolet light source to obtain a high-strength, low-temperature resistant, recyclable adhesive.

[0015] As a further preferred embodiment of the present invention, the reaction in step S1 is carried out under an inert atmosphere and at room temperature, and the reaction in step S2 is carried out at room temperature.

[0016] As a further preferred technical solution of the present invention, in step S1, the amount of DL-α-lipoic acid is 14.5 mmol, the amount of N,N'-carbonyldiimidazole is 10~20 mmol, and the amount of ethylenediamine is 80~200 mmol.

[0017] As a further preferred technical solution of the present invention, in step S2, the potassium carbonate is 15 mmol, potassium fluoroborate is 5-10 mmol, hexaethylene glycol di-p-toluenesulfonate is 2-7 mmol, and N-(tert-butoxycarbonyl)dopamine is 2-7 mmol.

[0018] As a further preferred technical solution of the present invention, in step S3, the volume ratio of dichloromethane to trifluoroacetic acid is 1~3:1.

[0019] As a further preferred technical solution of the present invention, in step S4, the benzo-21-crown-7 derivative B21C7-N is 10.01 mmol, 1,2-dithiapentane-3-pentanoic acid succinimide ester is 15~30 mmol, and triethylamine is 10~50 mmol.

[0020] As a further preferred embodiment of the present invention, in step S1, purification is performed by silica gel column chromatography, wherein the eluent is dichloromethane and methanol in a volume ratio of 1 to 5:1; and / or, in step S2, purification is performed by silica gel column chromatography, wherein the eluent is methanol and dichloromethane in a volume ratio of 20 to 40:1; and / or, in step S4, purification is performed by silica gel column chromatography, wherein the eluent is dichloromethane and methanol in a volume ratio of 10 to 30:1.

[0021] As a further preferred embodiment of the present invention, the wavelength of the ultraviolet light source is 365nm.

[0022] According to a second aspect of the present invention, the present invention also provides a high-strength, low-temperature resistant, recyclable adhesive, which is prepared by the above-described preparation method.

[0023] As a further preferred embodiment of the present invention, the adhesive is applied to the bonding area after being heated (e.g., to 110-130°C) to a fluid state during use, and then cooled to room temperature to achieve bonding. This adhesive is reusable; by heating the material (e.g., to 110-130°C), the material returns to a fluid state, and subsequent coatings can be applied for repeated use.

[0024] According to a second aspect of the present invention, the present invention also provides a method for recovering a high-strength, low-temperature resistant, recyclable adhesive, wherein the adhesive is selectively depolymerized in methanol solvent using sodium borohydride as a reducing agent, the adhesive is then selectively depolymerized, silica powder is added and evaporated, and after separation and purification, comonomers SC and SNH are recovered, wherein the purification method is the same as the method for preparing comonomers SC and SNH.

[0025] This invention designs and prepares a polythioctic acid-based adhesive. This type of adhesive achieves a harmonious balance of high adhesive strength, ultra-low temperature durability, and closed-loop recyclability by introducing benzo-21-crown-7 (B21C7) groups and ammonium functional groups into the molecular side chains. From a molecular design perspective, the disulfide bonds (S–S) in the polymer backbone have a lower rotational barrier than carbon-carbon bonds (C–C), which endows the material with high segmental mobility and toughness at low temperatures. Simultaneously, the reversible supramolecular network constructed by dynamic host-guest crosslinking and crown ether-water molecule hydrogen bonds effectively enhances the material's energy dissipation capacity and interfacial adhesive strength. More importantly, this unique molecular structure design ensures that the material maintains its colloidal structural integrity over a wide temperature range of -196℃ to 30℃, guaranteeing no shrinkage at low temperatures and preventing the formation of ice crystal defects, thus achieving stable adhesion. Furthermore, the dynamic properties of the disulfide bonds also endow the material with closed-loop depolymerization capabilities, enabling efficient monomer recovery. The strategy proposed in this invention provides an efficient and feasible solution for preparing high-performance recyclable adhesives that can be used stably in extreme environments.

[0026] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0027] (1) The present invention rationally designs the molecular structure from a chemical perspective, and synthesizes an adhesive in a room temperature environment by photo-initiated polymerization of thioctic acid. It has excellent adhesion strength at room temperature, with the best adhesion strength at around 25°C, which meets the requirements for conventional use. In addition, it also has excellent adhesion strength at liquid nitrogen temperature, and has excellent reusability and complete closed-loop recycling characteristics.

[0028] (2) Compared with traditional adhesive materials such as epoxy resin adhesives, phenolic resin adhesives, and acrylic adhesives, which require petroleum resources for preparation, the raw materials of the adhesive of the present invention, thioctic acid and benzo-21-crown-7 derivatives, are non-petrochemical resources, which can be naturally extracted or simply synthesized, and the source is pollution-free.

[0029] (3) The adhesive of the present invention exhibits excellent adhesion strength in low temperature and even extremely low temperature (-196℃) scenarios, which broadens its application scenarios. Attached Figure Description

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0031] Figure 1 The synthesis route of the copolymer monomer SNH in Example 1 is shown below;

[0032] Figure 2 The synthetic route for 1,2-dithiapentane-3-pentanoic acid succinimide ester (TANHS) in Example 1 is shown below.

[0033] Figure 3 The synthetic route for N-(tert-butyloxycarbonyl)dopamine (DA-Boc) in Example 1 is shown below.

[0034] Figure 4 The synthetic route for hexaethylene glycol di-p-toluenesulfonate (HEDP) in Example 1 is shown below;

[0035] Figure 5 The synthetic route for the benzo-21-crown-7 derivative (B21C7-boc) in Example 1 is shown below.

[0036] Figure 6 The synthetic route for the benzo-21-crown-7 derivative (B21C7-N) in Example 1 is shown below.

[0037] Figure 7 The synthetic route for the copolymer monomer SC in Example 1 is shown below;

[0038] Figure 8 Nuclear magnetic resonance (NMR) characterization of the copolymer monomer SNH in Example 1;

[0039] Figure 9 Mass spectrometry characterization of the molecule TANHS in Example 1;

[0040] Figure 10 The NMR structure of the DA-Boc molecule in Example 1 is characterized.

[0041] Figure 11 The NMR structure of the HEDP molecule in Example 1 is characterized.

[0042] Figure 12 The NMR structure of molecule B21C7-boc in Example 1 is characterized.

[0043] Figure 13 The NMR structure characterization of molecule B21C7-N in Example 1;

[0044] Figure 14 shows the NMR structure characterization of the copolymer SC in Example 1;

[0045] Figure 15 shows a comparative test of the adhesion strength of a series of adhesive materials on a room temperature glass substrate;

[0046] Figure 16 shows the adhesion strength of adhesive materials after bonding at room temperature for different times;

[0047] Figure 17 shows the adhesion strength of the adhesive material in the temperature range of -196℃ to 55℃;

[0048] Figure 18 shows a photograph of a teapot filled with liquid nitrogen after it has been bonded with adhesive material.

[0049] Figure 19 is a flowchart of the closed-loop recycling process for adhesive materials;

[0050] Figure 20 The NMR structures of the comonomer SC for the adhesive material before and after recycling are shown.

[0051] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0052] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0053] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0054] The raw materials DL-α-lipoic acid (99%), hexaethylene glycol (97%), anhydrous p-toluenesulfonyl chloride (99%), ethylenediamine (98%), 3-hydroxytyramine hydrochloride (99%, i.e., dopamine hydrochloride), deuterated dimethyl sulfoxide-D6 (deuterated degree 99.8%), deuterated chloroform-D (deuterated degree 99.8%), and N,N'-carbonyldiimidazole (CDI, 98%) were purchased from Shanghai Yuanye Biotechnology Co., Ltd.; the raw materials ditert-butyl dicarbonate (99%), trifluoroacetic acid (99%), potassium fluoroborate (99%), N,N'-disuccinimidyl carbonate (98%), and 4-dimethylaminopyridine (99%) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0055] Example 1

[0056] This embodiment provides a method for preparing a high-strength, low-temperature resistant, recyclable adhesive based on polythiooctanoic acid, specifically including:

[0057] Step 1: Preparation of comonomer SNH

[0058] Under a nitrogen atmosphere, DL-α-lipoic acid (3 g, 14.5 mmol) and N,N'-carbonyldiimidazole (CDI, 2.59 g, 16.0 mmol) were dissolved in 30 mL of dichloromethane and reacted with stirring at room temperature for 1 h. The resulting solution was then added dropwise over 1 h to a 30 mL solution of ethylenediamine (8 mL, 120 mmol) in dichloromethane, and the mixture was stirred overnight at room temperature to obtain a homogeneous yellow solution. The resulting reaction solution was then extracted three times with water (50 mL each time), and the organic phases were combined and concentrated to approximately 20 mL. The solution was purified by silica gel column chromatography (eluent: dichloromethane / methanol = 5:1) to give a pale yellow solid product (3.4 g, yield 88.43%). The synthetic route is described in [reference needed]. Figure 1 As shown.

[0059] Step 2: Preparation of comonomer SC

[0060] Triethylamine (19.40 mL, 139.59 mmol, 3.0 equivalent) was added to an anhydrous acetonitrile solution (300 mL) of DL-α-lipoic acid (9.6 g, 46.53 mmol, 1.0 equivalent) and N,N'-disuccinimidyl carbonate (DSC, 14.40 g, 55.84 mmol, 1.2 equivalent). The mixture was stirred at room temperature for 5 h to obtain a homogeneous yellow solution. The reaction mixture was filtered, and the filtrate was concentrated under reduced pressure to a volume of approximately 80 mL. The concentrate was then slowly poured into 600 mL of sodium bicarbonate aqueous solution [5% (w / v)], resulting in the precipitation of a pale yellow precipitate. The solid product was collected by vacuum filtration, thoroughly washed with water, and then dried under vacuum to obtain a yellow powder, 1,2-dithiapentane-3-pentanoic acid succinimide ester (TANHS, CAS No. 40846-94-4) (13.59 g, yield 93.77%). The synthetic route is described in [reference needed]. Figure 2 As shown.

[0061] Under a nitrogen atmosphere, tetrahydrofuran (94 mL) and a saturated sodium bicarbonate aqueous solution (56 mL) were added to a 250 mL round-bottom flask and mixed thoroughly. Dopamine hydrochloride (8.6 g, 45.3 mmol) was added to the mixture, followed by di-tert-butyl dicarbonate ((Boc)₂O, 10.9 g, 50 mmol). The mixture was stirred at room temperature for 2 h. After the reaction was complete, the reaction mixture was extracted with ethyl acetate (3 times, 100 mL each time). The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure. The resulting colorless liquid was allowed to stand, and a white crystalline solid, N-(tert-butyloxycarbonyl)-dopamine (DA-Boc, CAS No.: 37034-31-4) (10.24 g, yield 89.12%), precipitated. The synthetic route is described in [reference needed]. Figure 3 As shown.

[0062] Under ice-water bath cooling, potassium hydroxide (19 g, 336 mmol) was slowly added to a 40 mL solution of hexaethylene glycol (11.8578 g, 42 mmol) and anhydrous p-toluenesulfonyl chloride (16.2 g, 85 mmol) in dichloromethane. The reaction mixture was stirred for 4 h. After the reaction was complete, the mixture was extracted with deionized water (3 times, 80 mL each time). The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: ethyl acetate / petroleum ether = 2:1) to give the colorless liquid product hexaethylene glycol di-p-toluenesulfonate (HEDP, CAS No.: 42749-27-9) (15.32 g, yield 61.75%). The HEDP synthetic route is described in [reference needed]. Figure 4 As shown.

[0063] Potassium carbonate (2.07 g, 15 mmol) and potassium fluoroborate (0.944 g, 7.5 mmol) were dissolved in 100 mL of anhydrous acetonitrile, and the resulting mixture was heated to reflux temperature (78 °C). Separately, HEDP (2.9545 g, 5 mmol) and DA-Boc (1.2665 g, 5 mmol) were dissolved in 100 mL of anhydrous acetonitrile to prepare a solution, which was added dropwise to the above reflux system over 24 h using a dropping funnel. After the addition was complete, the reaction system continued to react at reflux temperature for 48 h, then cooled to room temperature. After filtration, the filtrate was concentrated under reduced pressure to approximately 80 mL. The remaining concentrate was extracted with saturated sodium chloride solution. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: methanol / dichloromethane = 30:1) to give a colorless liquid product, the benzo-21-crown-7 derivative (B21C7-boc) (1.21 g, yield 48.42%). The synthetic route is described in [reference needed]. Figure 5 As shown.

[0064] B21C7-boc was dissolved in dichloromethane, followed by the addition of trifluoroacetic acid (TFA) to prepare a reaction system with a dichloromethane / trifluoroacetic acid volume ratio of 2:1. The reaction mixture was stirred overnight at room temperature. After the reaction was completed, the solution was concentrated under reduced pressure to obtain the benzo-21-crown-7 derivative (B21C7-N), which can be further purified in subsequent reactions. The synthetic route is described in [reference needed]. Figure 6 As shown.

[0065] Triethylamine (3.49 mL, 25.0 mmol, 2.5 equivalents) was added to a 40 mL acetone solution of benzo-21-crown-7 derivative (B21C7-N, 4 g, 10.01 mmol, 1.0 equivalent) and succinimide 1,2-dithiapentane-3-pentanoic acid (TANHS) (7.585 g, 25 mmol, 2.5 equivalents). The mixture was stirred at room temperature for 18 h, and the reaction progress was monitored by thin-layer chromatography (TLC). After the reaction was complete, the mixture was filtered, and the filtrate was concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: dichloromethane / methanol = 20:1) to obtain the target product (1.86 g, yield 31.58%). The synthetic route is described in [reference needed]. Figure 7 As shown.

[0066] Step 3: Adhesive Synthesis

[0067] The comonomers SC and SNH are arranged according to... Figure 15 The different copolymer ratios (molar ratios) shown are mixed evenly, and then photo-initiated polymerization is carried out under a 365nm ultraviolet light source to obtain the adhesive material.

[0068] The structures of the synthesized molecules were determined using a Bruker AV III HD 400 MHz NMR spectrometer. The deuteration reagent used for molecules SNH, HEDP, B21C7-boc, and SC was deuterated chloroform, while the deuteration reagent used for molecules DA-boc and B21C7-N was deuterated DMSO. The test temperature was 25℃, and the frequency was 400 MHz. The results are shown in Figure 8-14. The characteristic structural peaks of the monomer molecules were distinguished from the NMR spectra, confirming the correctness of the synthesized SNH and SC molecular structures.

[0069] The performance of the above-prepared adhesive material samples was tested, as follows:

[0070] (1) Test the adhesion strength of the adhesive material on a glass substrate at room temperature.

[0071] Tensile properties were tested using an Instron 68TM-10 universal testing machine manufactured by ITW, USA. A 10 kN load cell was used, and the beam movement speed was set to 50 mm / min. Adhesion strength test results are as follows: Figure 15 As shown, the adhesive material exhibits the highest adhesion strength when the SC:SNH molar ratio is 1:2.

[0072] (2) Test the adhesion strength of the adhesive materials after bonding at room temperature for different times.

[0073] Tensile properties were tested using an Instron 68TM-10 universal testing machine manufactured by ITW, USA. A 10 kN load cell was used, and the beam movement speed was set to 50 mm / min. Using the adhesive material with a 1:2 SC:SNH molar ratio as the test object, tensile tests were performed on the bonded substrate after different placement times. The results are as follows: Figure 16 As shown, the material strength did not decrease significantly after different placement times, demonstrating excellent stability.

[0074] (3) Test the adhesion strength of the adhesive material in the temperature range of -196℃ to 55℃.

[0075] Tensile properties were tested using an Instron 68TM-10 universal testing machine manufactured by ITW, USA. A 10 kN load cell was used, and the beam movement speed was set to 50 mm / min. Using the adhesive material with a SC:SNH molar ratio of 1:2 as the test object, the adhesive strength was tested in a temperature range of -196℃ to 55℃. The results are as follows. Figure 17 As shown in the figure, the test results show that the adhesion strength of the material continuously increases from -196℃ to room temperature, reaching its maximum adhesion strength at room temperature. Subsequently, the adhesion strength gradually decreases with increasing temperature, reaching only 5.2 MPa at 55℃.

[0076] (4) Application test of adhesive materials at extremely low temperatures

[0077] Using the adhesive material with an SC:SNH molar ratio of 1:2 as the test object, the adhesive material was heated to 120°C to become a flowing liquid and then applied to the bonding area of ​​a broken teapot and teacup. After cooling to room temperature, the broken teapot and teacup were bonded together completely. Liquid nitrogen was then poured into the teapot and teacup, and the effect was as follows: Figure 18 As shown, the teapot and teacups remain intact, demonstrating the adhesive's excellent resistance to low-temperature adhesion.

[0078] Example 2

[0079] This embodiment provides a method for recycling adhesive materials, specifically:

[0080] In methanol solvent, sodium borohydride (NaBH4) was used as a reducing agent to selectively depolymerize the SC:SNH adhesive material prepared above with a molar ratio of 1:2, causing the dynamic disulfide bonds to break. Silica powder was then added and evaporated to obtain a crude product. The crude product was purified by column chromatography, successfully recovering the initial comonomers SC and SNH (Figure 19). Furthermore, when the recovered comonomers SC and SNH were mixed in the desired ratio and then photoinitiated under a 365 nm UV light source, the adhesive material could be obtained again.

[0081] Nuclear magnetic resonance (NMR) structural characterization was performed on the comonomer SC before and after recovery. Figure 20 The comparison of NMR before and after recovery showed that both NMR spectra had the characteristic SC peak of the monomer, indicating that the molecular structure was correct and confirming the ability of the monomer to be recovered in a closed loop.

[0082] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. A method for preparing a high-strength, low-temperature resistant, recyclable adhesive, characterized in that, Includes the following steps: S1. DL-α-lipoic acid and N,N'-carbonyldiimidazole were dissolved in a polar organic solvent and then added dropwise to a dichloromethane solution of ethylenediamine to carry out the reaction. After the reaction was completed, the reaction solution was extracted with water, the organic phases were combined and concentrated, and then purified by silica gel column chromatography to obtain the comonomer SNH with the following structure: ； S2. Potassium carbonate and potassium fluoroborate were dissolved in anhydrous acetonitrile, and hexaethylene glycol di-p-toluenesulfonate and N-(tert-butoxycarbonyl)dopamine were added. The mixture was heated under reflux at 70-90°C. After the reaction was completed, the mixture was cooled to room temperature and filtered. The concentrated solution was extracted with saturated sodium chloride solution. The organic phases were combined, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain the crude product. The crude product was then purified by silica gel column chromatography to obtain the benzo-21-crown-7 derivative B21C7-boc with the following structure: ； S3. The benzo-21-crown-7 derivative B21C7-boc was dissolved in dichloromethane, and trifluoroacetic acid (TFA) was added to carry out the reaction. After the reaction was completed, the mixture was concentrated under reduced pressure to obtain the benzo-21-crown-7 derivative B21C7-N with the following structure: ； S4. The benzo-21-crown-7 derivative B21C7-N and succinimide 1,2-dithiapentane-3-pentanoic acid were dissolved in acetone, and triethylamine was added to react. After the reaction was completed, the mixture was filtered and concentrated under reduced pressure to obtain the crude product. The crude product was then purified by silica gel column chromatography to obtain the comonomer SC with the following structure: ； S5. Mix the comonomers SC and SNH at a molar ratio of 1:0.5~2.5 until homogeneous, and perform photo-initiated polymerization under an ultraviolet light source to obtain a high-strength, low-temperature resistant, recyclable adhesive.

2. The method for preparing the high-strength, low-temperature resistant, recyclable adhesive according to claim 1, characterized in that, The reaction in step S1 is carried out under an inert atmosphere and at room temperature, and the reaction in step S4 is carried out at room temperature.

3. The method for preparing the high-strength, low-temperature resistant, recyclable adhesive according to claim 1, characterized in that, In step S1, the amount of DL-α-lipoic acid is 14.5 mmol, the amount of N,N'-carbonyldiimidazole is 10~20 mmol, and the amount of ethylenediamine is 80~200 mmol.

4. The method for preparing the high-strength, low-temperature resistant, recyclable adhesive according to claim 1, characterized in that, In step S2, the potassium carbonate is 15 mmol, potassium fluoroborate is 5-10 mmol, hexaethylene glycol di-toluenesulfonate is 2-7 mmol, and N-(tert-butyloxycarbonyl)dopamine is 2-7 mmol.

5. The method for preparing the high-strength, low-temperature resistant, recyclable adhesive according to claim 1, characterized in that, In step S4, the benzo-21-crown-7 derivative B21C7-N is 10.01 mmol, 1,2-dithiapentane-3-pentanoic acid succinimide ester is 15~30 mmol, and triethylamine is 10~50 mmol.

6. The method for preparing the high-strength, low-temperature resistant, recyclable adhesive according to claim 1, characterized in that, In step S1, purification is performed by silica gel column chromatography, wherein the eluent is dichloromethane and methanol in a volume ratio of 1 to 5:1; and / or, in step S2, purification is performed by silica gel column chromatography, wherein the eluent is methanol and dichloromethane in a volume ratio of 20 to 40:1; and / or, in step S4, purification is performed by silica gel column chromatography, wherein the eluent is dichloromethane and methanol in a volume ratio of 10 to 30:

1.

7. The method for preparing the high-strength, low-temperature resistant, recyclable adhesive according to claim 1, characterized in that, The wavelength of the ultraviolet light source is 365nm.

8. A high-strength, low-temperature resistant, recyclable adhesive, characterized in that, It is prepared by the preparation method described in any one of claims 1-7.

9. The high-strength, low-temperature resistant, recyclable adhesive according to claim 8, characterized in that, During use, the adhesive is heated to a fluid state and then applied to the bonding area, and the bonding is achieved by cooling to room temperature.

10. The method for recycling the high-strength, low-temperature resistant, recyclable adhesive according to claim 8, characterized in that, The adhesive was selectively depolymerized in methanol solvent using sodium borohydride as a reducing agent. Then, silica powder was added and evaporated. After separation and purification, the comonomers SC and SNH were recovered.

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