Controllable depolymerization and debonding high-performance epoxy adhesive as well as preparation method and application thereof

Abstract

The invention discloses a preparation method and application of a controllable depolymerization and debonding high-performance epoxy adhesive. The preparation method comprises the following steps: S1, reacting an aldehyde monomer with an alcohol monomer to obtain a polyhydroxy intermediate containing an acetal structure; the aldehyde monomer has at least one hydroxyl functional group; the alcohol monomer has more than three hydroxyl functional groups; s2, carrying out ring-opening addition and alkaline environment ring-closing epoxidation reaction on epoxy chloropropane and the polyhydroxy intermediate to obtain an epoxy monomer containing an acetal dynamic bond; and S3, compounding the epoxy monomer obtained in the step S2 with a temperature-resistant epoxy monomer, and mixing and curing with an amine curing agent to obtain the controllable depolymerization debonding thermosetting adhesive under the acidic condition, the temperature-resistant epoxy monomer comprises at least one of an epoxy monomer containing a naphthalene ring structure and an epoxy monomer containing a biphenyl structure.

Description

Technical Field

[0001] The present invention relates to the field of thermosetting adhesives, and in particular to a high-performance epoxy adhesive capable of controllably depolymerizing and debonding under acidic conditions, and a preparation method and application thereof. Background Art

[0002] Epoxy resin-based adhesives offer advantages such as high bonding strength, strong cohesive strength, excellent electrical insulation, chemical resistance, and low creep. They are widely used in the automotive, electrical and electronics, wind power generation, aerospace, and other fields, making them the most widely used class of synthetic adhesives. However, while the three-dimensional cross-linked network structure of epoxy resin adhesives imparts excellent cohesive and adhesive properties, it also prevents them from depolymerizing, dissolving, or melting after complete curing. This poses significant challenges to the rapid disassembly and repair of bonded structures during their service life, as well as their efficient, graded disassembly and recycling after they are scrapped.

[0003] By introducing dynamic bonds into the three-dimensional cross-linked network of epoxy resins, specific external field stimuli (such as light, heat, and pH) can induce reversible rupture of the internal dynamic bonds and controllable depolymerization of the three-dimensional cross-linked network. This provides a new approach for the design and preparation of thermosetting epoxy adhesives with controllable depolymerization and debonding. Extensive research has been conducted in this field, and novel adhesive systems with controllable depolymerization and degradation based on chemical dynamic bonds such as Diels-Alder (DA) bonds, disulfide bonds, β-ester bonds, borate bonds, and oxime ester bonds have been developed, achieving controlled dissociation of adhesives and controlled disassembly of bonded components.

[0004] For example, the patent specification with publication number CN106947054A discloses a method for preparing and disassembling a thermosetting material that can be quickly disassembled under mild conditions. The preparation method includes the following steps: synthesizing a polymer monomer containing multiple sensitive dynamic bonds; then cross-linking and curing with other monomers to obtain a three-dimensional cross-linked network structure thermosetting material containing multiple responsive dynamic bonds. This patented technology introduces dynamic bonds such as disulfide bonds, imine bonds, or acylhydrazone bonds into the cross-linked network structure of the thermosetting material. Under dual or multiple external stimuli such as heat, light, ultrasound, or a reducing agent, the material can be quickly disassembled under mild conditions, solving the problems of harsh disassembly conditions, long disassembly time, and single disassembly method for thermosetting materials.

[0005] However, the introduction of dynamic bonds also weakens the mechanical properties and heat resistance of the resin matrix to a certain extent, limiting the practical application of controlled depolymerization adhesives (especially in high-end technology fields). Therefore, the development of high-performance controlled depolymerization adhesives has attracted widespread attention from academia and industry.

[0006] The patent specification of the publication number CN119662177A previously applied for by the applicant discloses a kind of controllable debonding type thermosetting adhesive under certain conditions and its preparation method and application in composite material bonding and disassembly. This patented technology introduces acetal bond into the cross-linked network structure of thermosetting resin as the functional unit of controllable debonding, and the initial bonding strength of the obtained thermosetting adhesive is high. Under the external stimulation of acidity (organic solvent can be added as auxiliary if necessary), the acetal bond can be caused to break, and the cross-linked network of the adhesive resin matrix is broken, thereby realizing the controllable debonding of thermosetting adhesive under acidic conditions, solving the difficult problem that thermosetting adhesive is not easy to disassemble for the second time after bonding. The present invention introduces heat-resistant epoxy monomer on this basis, solves the problem that conventional controllable disassembly type adhesive is affected by the introduction of dynamic bond and thus cannot be applied in high temperature environment. Summary of the Invention

[0007] The present invention discloses a preparation technology and application method of a high-performance epoxy adhesive with controllable depolymerization and debonding, providing a new solution to the urgent demand for high-performance adhesives with controllable depolymerization and debonding in high-tech fields such as automobiles, electronics and electrical equipment, wind power generation, and aerospace.

[0008] The present invention provides a method for preparing a high-performance epoxy adhesive with controllable depolymerization and debonding. The specific invention contents are as follows: (1) The present invention introduces an acid-sensitive acetal structure into an epoxy monomer as a functional unit for controllable depolymerization and debonding, thereby preparing an epoxy monomer containing an acetal dynamic bond and imparting controllable depolymerization and debonding properties under acid stimulation. (2) A high-temperature resistant epoxy resin monomer is selected and compounded with an epoxy monomer containing an oxygen-containing acetal structure to improve the heat resistance and mechanical properties of the epoxy adhesive system.

[0009] The specific technical solutions are as follows:

[0010] [1] A method for preparing a high-performance epoxy adhesive with controllable depolymerization and debonding, comprising the steps of:

[0011] S1, an aldehyde monomer and an alcohol monomer react to obtain a polyhydroxy intermediate containing an acetal structure; the aldehyde monomer has at least one hydroxyl functional group; the alcohol monomer has three or more hydroxyl functional groups;

[0012] S2, epichlorohydrin and the polyhydroxy intermediate undergo ring-opening addition and ring-closing epoxidation in an alkaline environment to obtain an epoxy monomer containing an acetal dynamic bond;

[0013] S3, compounding the epoxy monomer obtained in step S2 with a heat-resistant epoxy monomer, mixing and curing with an amine curing agent, and obtaining a thermosetting adhesive capable of controllably depolymerizing and debonding under acidic conditions;

[0014] The heat-resistant epoxy monomer includes at least one of an epoxy monomer containing a naphthalene ring structure and an epoxy monomer containing a biphenyl structure.

[0015] In step S1 , the aldehyde monomer may include but is not limited to at least one of aldehyde functional group-containing monomers such as vanillin and p-hydroxybenzaldehyde.

[0016] In step S1 , the alcohol monomer may include but is not limited to at least one of polyol monomers such as glycerol, pentaerythritol, trimethylolpropane, and trimethylolethane.

[0017] In step S1 , the aldehyde monomer and the alcohol monomer may be added according to a molar ratio of aldehyde groups in the aldehyde monomer to the alcohol monomer of 1:1 to 1.5.

[0018] In step S1, the reaction temperature may be 80-100°C.

[0019] In step S1, the reaction solvent may be an organic solvent, which may include but is not limited to at least one of N,N-dimethylformamide (DMF) and petroleum ether.

[0020] In step S1, the reaction may be carried out in the presence of a catalyst. Further, the catalyst may include p-toluenesulfonic acid monohydrate, etc.

[0021] In step S2, the polyhydroxy intermediate and the epichlorohydrin can be added according to a molar ratio of hydroxyl groups in the polyhydroxy intermediate to the epichlorohydrin of 1:3 to 6.

[0022] In step S2, the reaction temperature of the ring-opening addition can be 80-120°C.

[0023] In step S2, the ring-opening addition reaction may be carried out in the presence of a catalyst. Further, the catalyst may include tetrabutylammonium bromide or the like.

[0024] In step S2, the temperature of the alkaline environment ring-closing epoxidation reaction can be 30-60°C.

[0025] In step S2, the alkaline environment can be obtained by adding a sodium hydroxide aqueous solution. Optionally, the molar ratio of sodium hydroxide in the added sodium hydroxide aqueous solution to the hydroxyl group in the polyhydroxy intermediate is 4 to 10:1. Optionally, the mass percentage concentration of sodium hydroxide in the sodium hydroxide aqueous solution is 30% to 60%.

[0026] In step S3, the temperature-resistant epoxy monomer preferably includes at least one of 2,2'-[1,6-naphthylenebis(oxymethylene)]dioxirane (CAS No.: 27610-48-6), 4,4'-biphenyl bisphenol diglycidyl ether (CAS No.: 2461-46-3), β,β'-dihydroxy-dinaphthalene diglycidyl ether (CAS No.: 1106-42-9), and 3,3'5,5'-tetramethylbiphenyl bisphenol diglycidyl ether (CAS No.: 85954-11-6), which can significantly improve the tensile strength, glass transition temperature and thermal decomposition temperature of the epoxy adhesive, as well as the initial bonding strength.

[0027] In step S3, the mass ratio of the heat-resistant epoxy monomer to the epoxy monomer obtained in step S2 may be 1:0.5-1.

[0028] In step S3, the amine curing agent may include but is not limited to at least one of isophoronediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethyltoluenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone and the like.

[0029] In step S3, the epoxy monomer obtained in step S2, the heat-resistant epoxy monomer, and the amine curing agent are mixed in a stoichiometric ratio for complete reaction. The primary amine and the secondary amine in the amine curing agent can react with the epoxy monomer obtained in step S2 and the epoxy group in the heat-resistant epoxy monomer.

[0030] In step S3, no special requirements are imposed on the curing conditions, and for example, the curing conditions generally required for amine curing agents in the art can be designed.

[0031] [2] A thermosetting adhesive capable of controlled depolymerization and debonding under acidic conditions, prepared according to the preparation method described in [1]. The thermosetting adhesive capable of controlled depolymerization and debonding under acidic conditions described in the present invention is an epoxy adhesive containing a three-dimensional dynamic cross-linked network and high-temperature resistant structural units.

[0032] [3] Application of the controllable depolymerization and debonding thermosetting adhesive according to [2] under acidic conditions in the controllable bonding and disassembly of composite materials and other structures.

[0033] In some embodiments, the application described in [3] is to treat the controllable depolymerization and debonding thermosetting adhesive under acidic conditions with an acid when disassembling the joint bonded by the controllable depolymerization and debonding thermosetting adhesive under acidic conditions to achieve depolymerization and debonding. The acid used in the acid treatment may include but is not limited to at least one of hydrochloric acid, sulfuric acid, etc. Further, the controllable depolymerization and debonding thermosetting adhesive under acidic conditions may be treated with an acidic solution containing an organic solvent. The controllable depolymerization and debonding thermosetting adhesive under acidic conditions of the present invention can quickly depolymerize and debond under acidic conditions with the assistance of an organic solvent. Furthermore, the organic solvent may include but is not limited to at least one of tetrahydrofuran, acetone, ethanol, etc.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention introduces acetal dynamic bonds and high-temperature-resistant groups into the three-dimensional cross-linked network structure of the epoxy adhesive, simultaneously imparting controllable depolymerization and debonding under acidic conditions and high-temperature resistance. This overcomes the problem that conventional controllable disassembly adhesives, which suffer from the reduced heat resistance caused by the introduction of dynamic bonds, cannot be used in high-temperature environments. The epoxy adhesive of the present invention exhibits high bonding strength, high-temperature resistance, and controllable depolymerization and debonding under acidic conditions, and has promising application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the chemical structure of the epoxy monomer containing acetal structure in Example 1. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0038] Example 1:

[0039] At 90°C, p-toluenesulfonic acid monohydrate (p-TsOH·H2O) was used as a catalyst. p-Hydroxybenzaldehyde and trimethylolpropane were reacted in a mixed solution of DMF and petroleum ether at a molar ratio of 1:1.02 for 24 hours. After removing the petroleum ether, the remaining solution was dropwise added to a 3wt% NaHCO3 aqueous solution to precipitate the product. The resulting product was washed with deionized water and vacuum dried at 80°C to obtain a dihydroxy intermediate containing an acetal structure.

[0040] The above-synthesized dihydroxy intermediate containing acetal structure and epichlorohydrin (molar ratio of 1:10) were used as raw materials, tetrabutylammonium bromide was used as catalyst, and the reaction was carried out at 110°C for 2h for ring-opening etherification. After cooling to 50°C, 50wt% NaOH aqueous solution was added dropwise to the raw material at a molar ratio of hydroxyl group to NaOH of 1:5 and the reaction was continued for 3h for ring closure. The organic phase was washed with deionized water to remove excess epichlorohydrin to obtain an epoxy monomer containing acetal structure ( Figure 1 ).

[0041] An epoxy monomer containing an acetal structure and an epoxy monomer containing a naphthalene ring structure, 2,2'-[1,6-naphthylenebis(oxymethylene)]dioxirane (CAS No.: 27610-48-6), are fully mixed (mass ratio of 1:1) to obtain a heat-resistant epoxy adhesive resin matrix with controllable depolymerization. Isophorone diamine is used as a curing agent and is fully stirred and mixed with the heat-resistant epoxy adhesive resin matrix with controllable depolymerization (molar ratio of epoxy group to amino group is 2:1) to obtain a heat-resistant epoxy adhesive with controllable depolymerization.

[0042] The glass transition temperature, thermal decomposition temperature and tensile strength of the heat-resistant epoxy adhesive with controlled depolymerization were analyzed. The results are shown in Table 1.

[0043] Carbon fiber reinforced epoxy composites (CFRP) were bonded with a heat-resistant epoxy adhesive with controlled depolymerization. Standard specimens for single lap tensile shear performance testing were prepared and the controlled depolymerization and debonding performance of the adhesive was analyzed.

[0044] At a temperature of 50°C, a 1M hydrochloric acid solution (solvent tetrahydrofuran and water volume ratio of 9:1) was used as a degradation solution to treat the single lap tensile shear test samples bonded with the above-mentioned heat-resistant epoxy adhesive with controlled depolymerization to study the debonding behavior of the bonded samples under acidic conditions. The test samples were placed in 1M HCl (solvent V THF :V H2O =9:1) degradation solution, after 5 hours of debonding treatment, the bond strength decreased from the initial 16.2MPa to 7.8MPa. After 10 hours of treatment, the bond strength decreased from the initial 16.2MPa to 2.6MPa. After 15 hours of debonding treatment, the adhesive was completely debonded and the CFRP bonded specimens were completely separated.

[0045] Comparative Example 1:

[0046] The difference from Example 1 is that the adhesive system does not contain a heat-resistant component (naphthalene ring epoxy resin) but only an acetal epoxy resin. First, the tensile strength, thermal decomposition temperature, and glass transition temperature of the acetal epoxy adhesive without a heat-resistant component were analyzed. The results are shown in Table 1. Second, the composite material samples bonded by the acetal epoxy adhesive without a heat-resistant component were analyzed after being subjected to 1M HCl (solvent VTHF :V H2O =9:1) degradation solution, and the bonding strength test was carried out with reference to Example 1. Similar bonding and debonding tests were carried out using a commercial epoxy adhesive, and the experimental results are shown in Table 2.

[0047] The high-performance epoxy adhesive with controlled depolymerization in Example 1 exhibits enhanced thermal stability, superior mechanical properties, and bond strength. Furthermore, under the same degradation conditions, both epoxy adhesives containing only acetal structures and those containing both acetal and naphthalene ring structures can undergo depolymerization and debonding under acid stimulation. However, commercial epoxy adhesives maintain relatively high bond strength, making effective debonding difficult.

[0048] Table 1

[0049] tensile strength Glass transition temperature Thermal decomposition temperature Example 1 Epoxy Adhesive Containing Acetal and Naphthalene Ring Structures 92.0MPa 189.6℃ 362.1℃ Comparative Example 1 Epoxy Adhesive Containing Acetal Structure 65.2MPa 119.5℃ 304.2℃

[0050] Table 2

[0051] Initial bonding strength Processing 5h Processing 10h Processing 15h Example 1 Epoxy Adhesive Containing Acetal and Naphthalene Ring Structures 16.2MPa 7.8MPa 2.6MPa 0MPa Comparative Example 1: Acetal-containing epoxy adhesive 13.9MPa 5.3MPa 0MPa 0MPa Comparative Example 1 Commercial Epoxy Adhesive 10.1MPa 9.8MPa 9.3MPa 9.0MPa

[0052] Example 2:

[0053] The epoxy monomer containing an acetal structure synthesized in Example 1 was fully mixed with 4,4'-biphenyl bisphenol diglycidyl ether (CAS No.: 2461-46-3) (mass ratio of 1:1) to obtain a heat-resistant epoxy adhesive resin matrix with controllable depolymerization. Isophorone diamine was used as a curing agent and was fully stirred and mixed with the heat-resistant epoxy adhesive resin matrix with controllable depolymerization (the molar ratio of epoxy group to amino group was 2:1) to obtain a heat-resistant epoxy adhesive with controllable depolymerization.

[0054] The glass transition temperature, thermal decomposition temperature, and tensile strength of the controllable depolymerization heat-resistant epoxy adhesive were analyzed. The results are shown in Table 3.

[0055] Glass fiber reinforced epoxy composite (GFRP) was bonded with a heat-resistant epoxy adhesive with controlled depolymerization. Standard specimens for GFRP single lap tensile shear performance test were prepared, and the controlled depolymerization and debonding behavior of the GFRP under acid stimulation was analyzed.

[0056] GFRP single-lap tensile shear test specimens bonded with the controllable depolymerization heat-resistant epoxy adhesive were treated with a 1M hydrochloric acid solution (9:1 volume ratio of acetone to water) at 80°C as a degradation solution to study the depolymerization and debonding behavior of the GFRP specimens under acidic conditions. GFRP single-lap tensile shear test specimens bonded with the controllable depolymerization heat-resistant epoxy adhesive were treated with a 1M hydrochloric acid solution (9:1 volume ratio of acetone to water) as a degradation solution to study the debonding behavior of the GFRP specimens under acidic conditions.

[0057] The test sample was placed in 1M HCl (solvent V 丙酮:V H2O =9:1) degradation solution, after 5 hours of debonding treatment, the bond strength decreased from the initial 14.6MPa to 7.0MPa. After 10 hours of treatment, the bond strength decreased from the initial 14.6MPa to 2.3MPa. After 15 hours of debonding treatment, the adhesive was completely debonded and the GFRP bonded specimens were completely separated.

[0058] Comparative Example 2:

[0059] The difference from Example 2 is that the epoxy adhesive system does not contain a heat-resistant component (epoxy monomer containing a biphenyl structure), and only contains acetal epoxy resin. First, the tensile strength, thermal decomposition temperature, and glass transition temperature of the acetal epoxy adhesive without a heat-resistant component were analyzed. The results are shown in Table 3. Second, the tensile strength, thermal decomposition temperature, and glass transition temperature of the composite material sample bonded by the acetal epoxy adhesive without a heat-resistant component were analyzed after 1M HCl (solvent V 丙酮 :V H2O =9:1) degradation solution, and the bonding strength test was performed with reference to Example 2. At the same time, similar bonding and debonding tests were carried out using a commercial epoxy adhesive, and the experimental results are shown in Table 2.

[0060] The high-temperature-resistant epoxy adhesive with controlled depolymerization in Example 2 exhibits superior thermal stability, mechanical properties, and bond strength. Furthermore, under the same degradation conditions, both epoxy adhesives containing only acetal structures and those containing both acetal and biphenyl structures can depolymerize and debond under acid stimulation. However, commercial epoxy adhesives still maintain relatively high bond strength, making effective debonding difficult.

[0061] Table 3

[0062] tensile strength Glass transition temperature Thermal decomposition temperature Example 2 Epoxy Adhesive Containing Acetal and Biphenyl Structures 84.7MPa 170.8℃ 355.6℃ Comparative Example 2 Epoxy Adhesive Containing Acetal Structure 65.2MPa 119.5℃ 304.2℃

[0063] Table 4

[0064] Initial bonding strength Processing 5h Processing 10h Processing 15h Example 2 Epoxy Adhesive Containing Acetal and Biphenyl Structures 14.6MPa 7.0MPa 2.3MPa 0MPa Comparative Example 2: Acetal-containing epoxy adhesive 13.9MPa 3.4MPa 0MPa 0MPa Comparative Example 2 Commercial Epoxy Adhesive 10.1MPa 9.5MPa 9.1MPa 8.8MPa

[0065] In summary, the epoxy adhesive of the present invention has excellent mechanical strength, bonding strength, and high-temperature resistance. At the same time, it can achieve controllable depolymerization and debonding under the stimulation of acid, which facilitates the disassembly, repair, and recycling of the bonded structure.

[0066] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a high-performance epoxy adhesive with controllable depolymerization and debonding, characterized in that: Including steps: S1, an aldehyde monomer and an alcohol monomer react to obtain a polyhydroxy intermediate containing an acetal structure; the aldehyde monomer has at least one hydroxyl functional group; the alcohol monomer has three or more hydroxyl functional groups; S2, epichlorohydrin and the polyhydroxy intermediate undergo ring-opening addition and ring-closing epoxidation in an alkaline environment to obtain an epoxy monomer containing an acetal dynamic bond; S3, compounding the epoxy monomer obtained in step S2 with a heat-resistant epoxy monomer, mixing and curing with an amine curing agent, and obtaining a thermosetting adhesive capable of controllably depolymerizing and debonding under acidic conditions; The heat-resistant epoxy monomer includes at least one of an epoxy monomer containing a naphthalene ring structure and an epoxy monomer containing a biphenyl structure.

2. The preparation method according to claim 1, characterized in that In step S1: The aldehyde monomer includes at least one of vanillin and p-hydroxybenzaldehyde; The alcohol monomer includes at least one of glycerol, pentaerythritol, trimethylolpropane, and trimethylolethane; The aldehyde monomer and the alcohol monomer are added according to a molar ratio of aldehyde group in the aldehyde monomer to the alcohol monomer of 1:1 to 1.5; The reaction temperature is 80-100°C.

3. The preparation method according to claim 1, characterized in that In step S2: The polyhydroxy intermediate and the epichlorohydrin are added according to a molar ratio of hydroxyl groups in the polyhydroxy intermediate to the epichlorohydrin of 1:3 to 6; The reaction temperature of the ring-opening addition is 80-120°C; The temperature of the alkaline environment ring-closing epoxidation reaction is 30 to 60°C; The alkaline environment is obtained by adding an aqueous sodium hydroxide solution; The molar ratio of sodium hydroxide in the added sodium hydroxide aqueous solution to the hydroxyl group in the polyhydroxy intermediate is 4 to 10:1; The mass percentage concentration of sodium hydroxide in the sodium hydroxide aqueous solution is 30% to 60%.

4. The preparation method according to claim 1, characterized in that In step S3: The heat-resistant epoxy monomer includes at least one of 2,2'-[1,6-naphthylenebis(oxymethylene)]dioxirane, 4,4'-biphenyl bisphenol diglycidyl ether, β,β'-dihydroxy-dinaphthalene diglycidyl ether, and 3,3'5,5'-tetramethylbiphenyl bisphenol diglycidyl ether; The mass ratio of the heat-resistant epoxy monomer to the epoxy monomer obtained in step S2 is 1:0.5-1; The amine curing agent includes at least one of isophorone diamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethyltoluenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl sulfone; The epoxy monomer obtained in step S2, the heat-resistant epoxy monomer and the amine curing agent are mixed in a completely reacted stoichiometric ratio.

5. A thermosetting adhesive capable of controllably depolymerizing and debonding under acidic conditions, prepared according to the preparation method according to any one of claims 1 to 4.

6. Use of the controllable depolymerization and debonding thermosetting adhesive under acidic conditions according to claim 5 in controllable bonding and disassembly.

7. The use according to claim 6, characterized in that When disassembling the joint bonded by the controllable depolymerization and debonding thermosetting adhesive under acidic conditions, the controllable depolymerization and debonding thermosetting adhesive under acidic conditions is treated with acid to achieve depolymerization and debonding.

8. The use according to claim 7, characterized in that The acid used in the acid treatment includes at least one of hydrochloric acid and sulfuric acid; The controllably depolymerizable and debonding thermosetting adhesive under acidic conditions is treated with an acidic solution containing an organic solvent.

9. The use according to claim 8, characterized in that The organic solvent includes at least one of tetrahydrofuran, acetone, and ethanol.

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