Curing method and application of polylipoic acid-based high polymer material

Abstract

The invention relates to the technical field of high polymer materials, and particularly provides a curing method and application of a polylipoic acid-based high polymer material. The curing method comprises the following steps: S100, mixing a polylipoic acid-based material and an epoxy curing agent to obtain a mixed system; and S200, carrying out a reaction on the mixed system at 20-160 DEG C for 1-12 hours to obtain the cured polylipoic acid-based material. A polylipoic acid-based material and an epoxy curing agent are uniformly mixed and react for 1-12 hours at the temperature of 20-160 DEG C, so that carboxyl and epoxy groups in the material are subjected to addition crosslinking, disulfide bonds participate in dynamic recombination at the same time, a double-dynamic three-dimensional network structure with ester bonds and disulfide bonds is formed, and the problems that the material is not resistant to high temperature and is slightly soft during use are never solved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology. Specifically, this invention provides a curing method and application of polythiooctanoic acid-based polymer materials. Background Technology

[0002] Currently, the demand for high-performance polymer materials continues to rise in fields such as aerospace, automotive manufacturing, electronic packaging, and medical devices. These applications not only require materials with excellent mechanical strength and high-temperature stability, but also need to meet sustainable development requirements such as recyclability, self-healing, and environmental degradation. However, while traditional thermosetting plastics such as epoxy resins, polyesters, and polyamides perform reliably under high-temperature or heavy-load conditions, they generally lack dynamic reversibility and environmentally friendly recycling capabilities, making it difficult to fully meet the innovative needs of "high-performance and sustainable" materials.

[0003] Poly(thioctic acid) (PTA) and its styrene copolymers exhibit a unique "dual dynamic bond" advantage due to the presence of both ring-opening / ring-closing disulfide bonds and carboxyl functional groups capable of participating in esterification reactions within their molecular chains. Literature reports that these materials possess excellent properties such as high toughness, self-healing ability, biocompatibility, and biodegradability; however, under high-temperature conditions, PTA-based materials are still prone to softening and flowing, and their compressive strength is relatively low, failing to meet the load-bearing and durability requirements of industrial applications such as structural adhesives or high-temperature coatings.

[0004] Although published literature and patents have conducted in-depth research on the synthesis, polymerization mechanism, and self-healing properties of polythiooctanoic acid (PPA), no systematic chemical crosslinking process for PPA with epoxy curing agents has been found to date. Therefore, there is an urgent need to develop a curing method that can significantly improve high-temperature deformation and compressive strength while retaining the dynamic self-healing and recyclable properties of PPA. Summary of the Invention

[0005] This invention provides a curing method and application for polythiooctanoic acid-based polymer materials. By uniformly mixing the polythiooctanoic acid-based material with an epoxy curing agent and reacting it at 20~160℃ for 1~12h, the carboxyl groups and epoxy groups in the material undergo addition crosslinking, and the disulfide bonds simultaneously participate in dynamic recombination, forming a dual dynamic three-dimensional network structure with both ester bonds and disulfide bonds. This curing method solves the problems of the material's inability to withstand high temperatures and its softness during use, while retaining the dynamic self-healing and recyclable properties of polythiooctanoic acid.

[0006] This invention provides a curing method for polythiooctanoic acid-based polymer materials. The curing method includes the following steps: S100, mixing the polythiooctanoic acid-based material with an epoxy curing agent to obtain a mixed system; S200, reacting the mixed system at 20~160℃ for 1~12h to obtain the cured polythiooctanoic acid-based material.

[0007] In any of the above technical solutions, in step S100, the polythioctic acid-based material includes a polymer containing thioctic acid structural units, including polythioctic acid, copolymers of thioctic acid and thioctic acid derivatives, and copolymers of thioctic acid with other monomers; the epoxy curing agent includes at least one or a combination of aliphatic epoxy resin, alicyclic epoxy resin, and aromatic epoxy resin.

[0008] In any of the above technical solutions, step S100 further includes: S101, adding a catalyst during the mixing process.

[0009] In any of the above technical solutions, the catalyst includes at least one of organotin compounds, organometallic complexes, Lewis acid metal halides, organic amine / phosphine compounds, and quaternary ammonium salt / inorganic base catalysts.

[0010] In any of the above technical solutions, in step S100, the ratio of polythiooctanoic acid-based material to epoxy curing agent is 100:(1~100) based on the molar ratio of carboxyl groups in polythiooctanoic acid-based material to epoxy groups in epoxy curing agent.

[0011] In any of the above technical solutions, step S100 specifically includes the following steps: S111, dissolving the polythiooctanoic acid-based material in a solvent to obtain a polythiooctanoic acid-based solution; S112, adding an epoxy curing agent to the polythiooctanoic acid-based solution for mixing treatment, and then removing the solvent to obtain a mixed system.

[0012] In any of the above technical solutions, step S100 specifically includes the following steps: S121, mixing the polythiooctanoic acid-based material and the epoxy curing agent in a solvent, and then removing the solvent to obtain a mixed system.

[0013] In any of the above technical solutions, step S100 specifically includes the following steps: S131, crushing the polythiooctanoic acid-based material into particles to obtain polythiooctanoic acid-based particles; S132, mixing the polythiooctanoic acid-based particles with an epoxy curing agent to obtain a mixed system.

[0014] In any of the above technical solutions, the solvent includes at least one or a combination of acetone, butanone, toluene, xylene, tetrahydrofuran, dimethyl sulfoxide, sulfolane, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, diethyl ether, and anisole.

[0015] This invention provides an application of a polythioctic acid-based polymer material in adhesives. The polythioctic acid-based polymer material prepared using any of the above-described curing methods is used to prepare polymer material products, including but not limited to adhesives, 3D printing materials, plastic products, cross-linked elastomers, coatings, sealants, or composite materials. Therefore, it includes the beneficial effects of any of the above-described technical solutions, which will not be elaborated upon here.

[0016] The technical effects that can be achieved by adopting the technical solution of the present invention are as follows: 1. The rigid framework formed by ester bond crosslinking gives the material the heat resistance to maintain its shape at high temperatures, while the ester bond and disulfide bond work together to bear external forces, which significantly improves the compressive strength of the cured body compared with the uncured material, meeting the requirements of structural adhesives and high-strength coatings under harsh load conditions. 2. Disulfide bonds can be continuously broken and recombined under high temperature or catalysis. Once microcracks or damage occur in the material, they can be quickly closed and their performance restored by heating or chemical triggering. At the same time, the entire network can be disassembled and recombined in a reducing medium, enabling multiple reprocessing and recycling, greatly extending service life and reducing environmental burden. 3. It allows for flexible selection of various mixing methods such as solvent method, co-solution method or particle method, and combinations of epoxy type, catalyst system and solvent. It also allows for fine control of crosslinking density, curing speed and final performance, making it easy to quickly optimize the formula in various application scenarios. Detailed Implementation

[0017] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0018] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0019] To make the above-mentioned objectives, features and advantages of this aspect more apparent and understandable, specific embodiments of this aspect are described in detail below.

[0020] Polythioctic acid (Polythioctic Acid) and its styrene copolymers exhibit a unique "dual dynamic bond" advantage due to the presence of both ring-opening / ring-closing disulfide bonds and carboxyl functional groups capable of participating in esterification reactions within their molecular chains. Literature reports that these materials possess excellent properties such as high toughness, self-healing ability, biocompatibility, and biodegradability. However, under high-temperature conditions, Polythioctic Acid-based materials are still prone to softening and flowing, and their compressive strength is relatively low, failing to meet the load-bearing and durability requirements of industrial applications such as structural adhesives or high-temperature coatings.

[0021] Although published literature and patents have conducted in-depth research on the synthesis, polymerization mechanism, and self-healing properties of polythiooctanoic acid (PPA), no systematic chemical crosslinking process for PPA with epoxy curing agents has been found to date. Therefore, there is an urgent need to develop a curing method that can significantly improve high-temperature deformation and compressive strength while retaining the dynamic self-healing and recyclable properties of PPA.

[0022] Specifically, this embodiment provides a curing method for a polythiooctanoic acid-based polymer material, the curing method comprising the following steps: S100. The polythiooctanoic acid-based material is mixed with an epoxy curing agent to obtain a mixed system; S200. The mixture is reacted at 20~160℃ for 1~12h to obtain the cured polythiooctanoic acid-based material.

[0023] Preferably, a three-dimensional network is constructed by using the dynamically exchangeable chemical bonds of polythiooctanoic acid (PPA)-based materials and epoxy curing agents. Under heating conditions, the carboxyl groups at the ends of the PPA molecular chains and on the main chain undergo ring-opening addition to the epoxy small-molecule curing agent, generating stable -COO- ester bonds. These serve as permanent or semi-permanent crosslinking points, providing a rigid framework for the network and ensuring dimensional stability and compressive strength at high temperatures. During the curing process, the disulfide bonds in PPA continuously break and recombine under high temperatures. Simultaneously, the hydroxyl ester groups generated by the reaction of carboxyl groups and epoxy groups can also undergo dynamic ester exchange under high temperatures or with a catalyst, achieving dual dynamic exchange within the network. This endows the cured body with excellent self-healing capabilities, stress relaxation characteristics, and reprocessable and recyclable properties.

[0024] The aforementioned dual dynamic crosslinking mechanism enables the permanent ester bond skeleton to prevent the material from softening at high temperatures. Simultaneously, the ester bonds and disulfide bonds work together to bear external forces, significantly improving compressive strength and meeting the requirements of structural adhesives and high-load coatings. Furthermore, after damage, the material can complete crack closure and performance recovery through heating or chemical triggering, and can fracture and reassemble in high-temperature or reducing solvents for reprocessing. On the other hand, the mixing-solvent removal-thermal curing process can be flexibly applied to solvent methods, solid-phase particle methods, or one-step mixing methods, and is suitable for various molding processes such as injection molding, coating, casting, and 3D printing.

[0025] Preferably, in step S100, the polythioctic acid-based material includes polymers containing thioctic acid structural units, including polythioctic acid, copolymers of thioctic acid and thioctic acid derivatives, and copolymers of thioctic acid with other monomers. This type of material not only carries abundant carboxyl functional groups but also possesses a disulfide ring structure capable of ring-opening / ring-closing. The aliphatic, alicyclic, or aromatic epoxy resins used in conjunction with it are multifunctional, with their molecules carrying multiple epoxy groups. During mixing, the two materials interpenetrate and come into close contact, laying a good foundation for the subsequent thermosetting reaction. Upon heating, the carboxyl groups on the polythioctic acid molecular chain undergo ring-opening addition to the epoxy groups, forming stable ester bond crosslinking points. Simultaneously, the disulfide bonds and hydroxyl ester groups reversibly break and recombine under the dual action of high temperature and a catalyst, giving the entire network both a permanent "skeleton" and dynamic "activity." This dual crosslinking mechanism, on the one hand, endows the material with excellent high-temperature stability and mechanical strength through the newly formed ester bond network, enabling it to maintain its shape and size even at high temperatures; on the other hand, the continuous breaking and recombination of disulfide bonds adds self-healing and stress relaxation capabilities to the material. When external forces or microcracks occur, it can self-heal within a short time through temperature or chemical triggering, extending its service life. More importantly, this dynamic reversibility also supports the reprocessing or recycling of the cured body while meeting performance requirements, truly achieving an organic combination of high performance and sustainability.

[0026] Furthermore, the epoxy curing agent can be selected from meso-1,2:3,4-diepoxybutane, butadiene diepoxide, 1,5-hexadiene diepoxide, dicyclopentadiene diepoxide, 1,2,7,8-diepoxyoctane, 2,2'-(2,2,3,3,4,4,5,5-octafluorohexane-1,6-diyl)bis(ethylene oxide), 5,5-dimethyl-1,3-bis(ethylene oxide-2-ylmethyl)imidazolidine-2,4-dione, 1,3-bis(3-glycidoxypropyl)-1,1,3,3-tetramethyldisiloxane, tetraepoxycyclosiloxane, tetraepoxycyclohexylethyl-2,4,6,8-tetramethylcyclotetrasiloxane, 1,3-bis(N,N-diglycidylaminomethyl) 9,9-bis[(2,3-epoxypropoxy)phenyl]fluorene, 9,9-bis(4-epoxypropyloxy-3-tolyl)fluorene, 9,9-bis[4-(2,3-epoxypropoxyethoxy)phenyl]fluorene, 2,2′-[cyclohexylidene bis(4,1-phenyleneoxymethylene)]bis[epoxyethylene], 1,5-bis(epoxypropoxypropyl)-3-phenyl-1,1,3,5,5-pentamethyltrisiloxane, tri(epoxypropoxypropyldimethylsiloxy)phenylsilane, resorcinol diglycidyl ether, triglycidyl-m-aminophenol, triglycidyl-m-cresol, triglycidyl-p-aminophenol, N,N,N',N' -Tetraglycidyl-4,4'-diaminodiphenyl ether, bisphenol A (2,3-dihydroxypropyl)glycidyl ether, vinylcyclohexene dioxide, diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 2,2'-[oxybis(2,1-ethyleneoxymethylene)]bis(ethylene oxide), ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, glycerol diglycidyl ether, bisphenol F diglycidyl ether, bisphenol A diglycidyl ether, 4,4'-biphenyl bisphenol diglycidyl ether, bisphenol A propoxylated diglycidyl ether, 1,4-bis[(glycidyloxy)methyl]cyclohexane, 3,3'',5,5''-tetra(2,3-dihydroxypropyl)diphenyl ether Methylbiphenyl bisphenol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, tri(4-hydroxyphenyl)methane triglycidyl ether, pentaerythritol glycidyl ether, epoxidized soybean oil, (2b,3a,16a,17a)bisepoxy-17b-acetoxy-5α-androstane, 1,4-cyclohexanediethanol bis(3,4-epoxycyclohexanecarboxylic acid) ester, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylic acid ester, 4,5-epoxytetrahydrophthalic acid diglycidyl ester (4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester), tri(epoxyethylene-2-ylmethyl)benzene-1,3,5-tricarboxylic acid ester, bis(7-oxabicyclo[4.1]).At least one of the following: [0]3-heptamethyl) adipate, 1,2-cyclohexanedicarboxylic acid diglycidyl ester, 4-cyclohexene-1,2-dicarboxylic acid diglycidyl ester, bis[4-(glycidoxy)phenyl]methane, 9,10:12,13-diepoxyoctadecanoic acid, and triglycidyl isocyanurate.

[0027] The diverse range of epoxy curing agents mentioned above can be flexibly selected according to the performance requirements of the target application, thereby greatly expanding the controllability of the curing system and improving the material properties: aliphatic epoxy resins such as meso-diepoxybutane and diepoxybutadiene have low viscosity, excellent electrical insulation and toughness; alicyclic epoxy resins (such as dicyclopentadiene epoxy and diepoxyoctane) take into account high temperature weather resistance and chemical resistance; aromatic epoxy resins (such as bisphenol A glycidyl ether and biphenyl bisphenol glycidyl ether) can significantly improve crosslinking density and rigidity, heat resistance and corrosion resistance; while epoxy resins containing silicon or fluorene structures (such as tetraepoxycyclosiloxane and 9,9-bis(epoxypropoxy)fluorene) endow the cured body with superior UV aging resistance, low dielectric constant or intermolecular combing space effect. By selecting or combining these epoxy resins, not only can the crosslinking density and glass transition temperature of the network be precisely adjusted, but also multiple functions such as low temperature curing, high toughness, excellent insulation, chemical resistance and weather resistance can be achieved.

[0028] Preferably, step S100 further includes: S101, adding a catalyst during the mixing process. The catalyst includes at least one of organotin compounds, organometallic complexes, Lewis acid metal halides, organic amine / phosphine compounds, and quaternary ammonium salt / inorganic base catalysts. Simultaneous addition of the catalyst during the mixing of the polythiooctanoic acid-based material and the epoxy curing agent can significantly accelerate the ring-opening addition reaction of carboxyl groups to epoxy groups and the reversible exchange of disulfide bonds, thereby rapidly constructing a uniform and dense three-dimensional network under milder conditions. In general, the addition of the catalyst not only shortens the reaction time but also helps to achieve a uniform distribution of crosslinking points, avoiding excessive or insufficient crosslinking in certain areas, and improving the mechanical consistency and thermal stability of the cured body. Simultaneously, the catalyst also promotes the dynamic transesterification of hydroxyl ester groups: under thermal triggering, they can accelerate the exchange and recombination of ester groups, making the self-healing and stress relaxation properties of the material more efficient.

[0029] Furthermore, the catalyst can be selected from dibutyltin dilaurate, dioctyltin dilaurate, stannous octanoate, di(dodecyl sulfide)dibutyltin, dibutyltin diacetate, dibutyltin dimaleate, dithiol butyltin, thiol dioctyltin, tin acetylacetonate, organobismuth, chromium trichloride, chromium 3,5-diisopropylsalicylate, chromium 5-tert-butylfuranate, chromium 5-isopropylfuranate, chromium 2-ethylhexanoate, fatty acid chromium, chromium acetylacetonate, molybdenum acetylacetonate, aluminum acetylacetonate, cobalt(II) acetylacetonate, and cobalt(III) acetylacetonate. Manganese acetylacetone, zirconium acetylacetone, vanadium acetylacetone, vanadium oxyacetylacetone, ruthenium acetylacetone, iron acetylacetone, cobalt acetylacetone, nickel acetylacetone, titanium oxide acetylacetone, palladium acetylacetone, gallium acetylacetone, rhodium dicarbonyl acetylacetone, neodymium (III) acetylacetone, trifluoromethanesulfonates of lanthanides (yttrium, scandium, dysprosium, samarium, gadolinium, and neodymium), manganese perchlorate, magnesium perchlorate, calcium perchlorate, cesium perchlorate, barium perchlorate, ferric perchlorate, zinc dichloride, cadmium dichloride, mercuric dichloride, aluminum trichloride, aluminum tribromide, gallium trichloride, ferric trichloride, Tin tetrachloride, titanium tetrachloride, zirconium tetrachloride, vanadium tetrachloride, antimony pentafluoride, antimony pentachloride, tungsten pentachloride, boron trichloride, boron trifluoride, boron tribromide, AlRmX3-m (R is methyl, ethyl, or other alkyl groups, X is a halogen), triazine trimerizing catalyst, bis(dimethylaminomethyl)benzene, N,N-dimethylbenzylamine, N,N-diethylbenzylamine, triethylamine, triethanolamine, N,N-dimethylethanolamine (DMEA), tetrabutylammonium bromide, triethylbenzylammonium chloride, pyridine, N,N'-dimethylpyridine, sodium hydroxide, hydroxide At least one or a combination of potassium, sodium bicarbonate, sodium carbonate, triphenylphosphine, triphenylphosphine sulfide, dibromotriphenylphosphine, dichlorotriphenylphosphine, triphenylphosphine borane, triphenylphosphine hydrobromide, triphenylphosphine diiodide, N-tert-butoxycarbonyl-amidinium triphenylphosphine, triphenylphosphine rhodium chloride, triphenylphosphine palladium acetate, bis(triphenylphosphine)ammonium chloride, tetra(triphenylphosphine)palladium, bis(triphenylphosphine)dicarbonyl nickel, tri(triphenylphosphine)cobalt chloride, bis(triphenylphosphine)cobalt chloride, bis(triphenylphosphine)dichloride palladium(II), and dichlorotetra(triphenylphosphine)ruthenium.

[0030] The aforementioned diverse catalysts encompass various types, ranging from organotin and chromium-based complexes to organic amines, phosphorus compounds, and strong bases. They can be flexibly selected based on formulation and process requirements, enabling precise control of crosslinking reaction kinetics and network structure within the curing system. Specifically, organotin and Lewis acid catalysts exhibit significant activation effects on epoxy rings, rapidly forming ester bonds at lower temperatures; organic amines / phosphine and quaternary ammonium salts enhance the nucleophilicity of carboxyl groups, accelerating the crosslinking reaction rate. This diverse catalytic system not only shortens curing time and reduces energy consumption but also optimizes network uniformity based on the acidity, basicity, and coordination ability of the selected catalyst, achieving an optimal balance in terms of high-temperature stability, mechanical strength, self-healing efficiency, and subsequent recycling processing.

[0031] Preferably, in step S100, the ratio of polythiooctanoic acid-based material to epoxy curing agent is 100:(1~100) based on the molar ratio of carboxyl groups in polythiooctanoic acid-based material to epoxy groups in epoxy curing agent. This not only allows for precise control of crosslinking point density and ensures the optimal balance between the dynamic exchange of ester bond network and disulfide bond, but also avoids the problem of brittleness caused by excessive epoxy or low strength due to insufficient epoxy. Within this range, the cured body exhibits excellent mechanical properties and thermal stability, while retaining good self-healing and recyclability. The process operation is also simpler and more repeatable.

[0032] Preferably, step S100 specifically includes the following steps: S111, dissolving the polythiooctanoic acid-based material in a solvent to obtain a polythiooctanoic acid-based solution; S112, adding an epoxy curing agent to the polythiooctanoic acid-based solution for mixing, and then removing the solvent to obtain a mixed system; when mixing by solvent method, the polythiooctanoic acid-based material is first fully dissolved, the molecular chain is completely unfolded, and the carboxyl groups and disulfide rings are uniformly exposed in the solution; at this time, the addition of epoxy curing agent, the solvent medium ensures high diffusion and close contact between the two molecules, so that the subsequent esterification reaction and disulfide bond recombination can be carried out simultaneously at the microscopic level. The presence of solvent not only improves the mixing uniformity, but also leaves a premixed system with uniform dispersion and consistent distribution of crosslinking active sites after solvent removal, thereby ensuring that the final cured body has a higher crosslinking density and a more homogeneous network structure.

[0033] Preferably, step S100 specifically includes the following steps: S121, mixing the polythiooctanoic acid-based material and the epoxy curing agent in a solvent, and then removing the solvent to obtain a mixed system. This method of co-dissolving the polythiooctanoic acid-based material and the epoxy curing agent in the same solvent allows for true molecular-level mixing, bringing the relative positions of the carboxyl and epoxy groups closer together, and significantly reducing the initial activation energies of ring-opening addition and disulfide bond exchange. This "co-solution" strategy enables deep cross-linking at lower temperatures or in shorter times, while avoiding uneven network density caused by localized uneven material concentration, resulting in a better balance in mechanical strength, thermal stability, and self-healing properties of the cured body.

[0034] Furthermore, the solvents include at least one or a combination of acetone, butanone, toluene, xylene, tetrahydrofuran, dimethyl sulfoxide, sulfolane, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, diethyl ether, and anisole. These solvents each possess different polarities and boiling ranges, providing optimal solubility and dispersibility for polythiooctanoic acid-based materials and various epoxy curing agents. Simultaneously, their volatility ensures a rapid and thorough solvent removal process, avoiding interference from solvent residues on the crosslinking reaction. By flexibly combining these solvents, the viscosity and mass transfer efficiency of the mixed system can be precisely controlled, allowing the carboxyl and epoxy groups to fully contact in solution, promoting the simultaneous crosslinking of ester bonds and the recombination of disulfide bonds, thereby obtaining a more uniform and denser dual-dynamic network structure.

[0035] Preferably, step S100 specifically includes the following steps: S131, crushing the polythiooctanoic acid (PPA)-based material into particles to obtain PPA-based particles; S132, mixing the PPA-based particles with an epoxy curing agent to obtain a mixed system. When using the particle mixing method, the PPA-based material is mechanically crushed into micron- or nano-sized particles, significantly increasing the specific surface area. Subsequently, it is mixed with the epoxy curing agent, and the carboxyl groups on the particle surface rapidly react with the epoxy active groups to form a preliminary cross-linked network. During the thermosetting stage, the inner cyclic disulfide bonds are also broken and recombined, ultimately constructing a three-dimensional interconnected dual-dynamic network between and within the particles. This "particle and curing agent" premixed system requires no solvent removal, making the process more environmentally friendly and simpler, and enabling rapid curing and efficient self-healing.

[0036] In summary, this embodiment involves uniformly mixing a polythiooctanoic acid-based material rich in carboxyl groups and disulfide rings with a multifunctional epoxy curing agent under solvent or solid-phase conditions, and then reacting it at 20-160°C for 1-12 hours. Through the dual mechanisms of crosslinking of ester bonds and dynamic recombination of disulfide bonds, a robust and reversible three-dimensional network is simultaneously constructed, thereby achieving high-temperature stability, excellent mechanical properties, and dynamic self-healing in one step.

[0037] Example 1 This embodiment provides a curing method for polythiooctanoic acid-based polymer materials, including the following steps: S111. Dissolve 5 g of polythiooctanoic acid in 50 mL of acetone to obtain a polythiooctanoic acid solution; S112. While adding 0.85 g of butadiene diepoxidized to the polythioctic acid solution for mixing, add 2 drops of dioctyltin dilaurate. After stirring evenly, pour the mixture into a polytetrafluoroethylene mold, remove the solvent, and obtain the mixed system. S200, the mixture is cured at 130℃ for 8 h to obtain cured polythiooctanoic acid.

[0038] Example 2 This embodiment provides a curing method for polythiooctanoic acid-based polymer materials, including the following steps: S121. While mixing 5 g of thioctic acid-styrene copolymer in 50 mL of dimethyl sulfoxide, add 1.12 g of tetracyclooxysiloxane and 60 mg of triphenylphosphine. After thorough mixing, pour into a polytetrafluoroethylene mold, remove the solvent, and obtain the mixed system.

[0039] S200. The mixture was reacted at 100°C for 12 h to obtain the cured thioctic acid-styrene copolymer.

[0040] Example 3 This embodiment provides a curing method for polythiooctanoic acid-based polymer materials, including the following steps: S131. 5 g of polythiooctanoic acid is crushed into particles to obtain polythiooctanoic acid particles; S132. Polythioctic acid granules and 1.21 g diglycidyl ether are extruded and mixed evenly through a twin-screw extruder to obtain a mixed system. S200, the mixture is reacted at 160℃ for 2 h to obtain cured polythiooctanoic acid.

[0041] Example 4 This embodiment provides a curing method for polythiooctanoic acid-based polymer materials. The specific steps are the same as in Example 1, except that the epoxy curing agent, solvent, and catalyst are selected and their contents are different, as shown in Table 1. Table 1 Example 5 This embodiment provides a curing method for polythiooctanoic acid-based polymer materials. The specific steps are the same as in Example 2, except that the epoxy curing agent, solvent, and catalyst are selected and their contents are different, as shown in Table 2. Table 2 Example 6 This embodiment provides a curing method for polythiooctanoic acid-based polymer materials. The specific steps are the same as in Example 3, except that the polythiooctanoic acid-based polymer raw materials, epoxy curing agents, and catalysts are selected and their contents are different, as shown in Table 3. Table 3 Comparative Example 1 This embodiment provides a polythioctic acid, which is synthesized in the laboratory.

[0042] Comparative Example 2 This embodiment provides a polythioctic acid copolymer, which is synthesized in the laboratory.

[0043] Performance testing Examples 1-6 were tested for self-healing efficiency, tensile strength, Young's modulus, rheological temperature, and thermal stability, respectively. Examples 1-2 were tested for tensile strength, Young's modulus, and rheological temperature, respectively. Examples 3, 6, and Examples 1-2 were tested for toughness and fracture strength, respectively. The test results are shown in Table 4. Table 4 Test conclusion: The curing method provided by this invention can significantly improve the properties of polythioctic acid and its copolymers in many aspects, perfectly balancing the self-healing properties, mechanical properties and heat resistance of the materials. (1) The self-healing efficiency of the cured products in all embodiments of this application remains above 94% (up to 97.83% in Example 5-1), and there is no significant decrease compared with the comparative raw materials. This indicates that the curing process of this application successfully retains the inherent and efficient self-healing ability of the polythiooctanoic acid system while greatly enhancing other properties.

[0044] (2) The tensile strength in the embodiments of this application is increased by orders of magnitude compared with the comparative example, and the rigidity of the material is greatly improved. In particular, the tensile strength of Example 5-1 is as high as 12.82 MPa, which is more than 34 times that of the comparative example 1, and the Young's modulus reaches 320.56 MPa, proving that it has extremely strong resistance to deformation and transforms from a soft elastomer into a strong and tough engineering material. In addition, Examples 3, 6-1, and 6-4 are prepared under solvent-free conditions, and their toughness and fracture strength have increased by 2-3 times, proving that the product can still effectively resist crack propagation under high strength and has both high strength and high toughness.

[0045] (3) The rheological temperatures in the embodiments of this application are all higher than those in the comparative examples. The polythioctic acid in Comparative Example 1 softens and flows at 80°C, while the rheological temperature of the product of this invention is at least 120°C and at most over 150°C, significantly widening the thermal stability window. In terms of long-term thermal stability, after prolonged heating at 100-120°C, all the cured products in the embodiments of this application maintain stable properties and do not soften, flow, or deform, meeting the application requirements in high-temperature environments.

[0046] In summary, the curing method of this application, by uniformly mixing polythioctic acid-based materials with epoxy curing agents, causes the carboxyl groups and epoxy groups in the material to undergo ring-opening cross-linking reactions, while disulfide bonds simultaneously participate in dynamic recombination, forming a dual dynamic three-dimensional network structure with both hydroxyl ester groups and disulfide bonds. This solves the problems of the material's inability to withstand high temperatures and its softness during use, while retaining the dynamic self-healing and recyclable properties of polythioctic acid. It solves a long-standing technical problem in this field and can be used to prepare polymer material products, including but not limited to adhesives, 3D printing materials, plastic products, cross-linked elastomers, coatings, sealants, or composite materials.

[0047] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0048] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for curing a polythiooctanoic acid-based polymer material, characterized in that, The curing method includes the following steps: S100. The polythiooctanoic acid-based material is mixed with an epoxy curing agent to obtain a mixed system; S200. The mixture is reacted at 20~160℃ for 1~12h to obtain the cured polythiooctanoic acid-based material.

2. The curing method according to claim 1, characterized in that, In step S100, The polythioctic acid-based material includes polymers containing thioctic acid structural units, including polythioctic acid, copolymers of thioctic acid and thioctic acid derivatives, and copolymers of thioctic acid with other monomers. The epoxy curing agent includes at least one or a combination of aliphatic epoxy resin, alicyclic epoxy resin, and aromatic epoxy resin.

3. The curing method according to claim 1, characterized in that, Step S100 further includes: S101, A catalyst is added during the mixing process.

4. The curing method according to claim 3, characterized in that, The catalyst includes at least one of organotin compounds, organometallic complexes, Lewis acid metal halides, organic amine / phosphine compounds, and quaternary ammonium salt / inorganic base catalysts.

5. The curing method according to claim 1, characterized in that, In step S100, the ratio of the polythiooctanoic acid-based material to the epoxy curing agent is 100:(1~100) based on the molar ratio of carboxyl groups in the polythiooctanoic acid-based material to epoxy groups in the epoxy curing agent.

6. The curing method according to any one of claims 1 to 5, characterized in that, Step S100 specifically includes the following steps: S111. Dissolve the polythiooctanoic acid-based material in a solvent to obtain a polythiooctanoic acid-based solution; S112. After adding an epoxy curing agent to the polythioctic acid solution and performing the mixing treatment, the solvent is removed to obtain the mixed system.

7. The curing method according to any one of claims 1 to 5, characterized in that, Step S100 specifically includes the following steps: S121. The polythiooctanoic acid-based material and the epoxy curing agent are mixed in a solvent, and then the solvent is removed to obtain the mixed system.

8. The curing method according to any one of claims 1 to 5, characterized in that, Step S100 specifically includes the following steps: S131. The polythiooctanoic acid-based material is crushed into particles to obtain polythiooctanoic acid-based particles; S132. The polythiooctanoic acid particles and the epoxy curing agent are mixed to obtain the mixed system.

9. The curing method according to any one of claims 6 or 7, characterized in that, The solvent includes at least one or a combination of acetone, butanone, toluene, xylene, tetrahydrofuran, dimethyl sulfoxide, sulfolane, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, diethyl ether, and anisole.

10. The application of a polythiooctanoic acid-based polymer material prepared by the curing method according to any one of claims 1 to 9 in adhesives, characterized in that, The material is used to prepare polymer material products.

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