Near-infrared light self-healing epoxy resin and preparation method and application thereof

Abstract

The application discloses a kind of near-infrared light self-healing epoxy resin and its preparation method and application.The preparation method includes the following steps: epoxy resin and boric acid derivative are reacted to obtain epoxy resin containing borate ester bond, furan derivative and maleimide derivative are reacted to obtain mixed solution containing Diels-Alder bond, the mixed solution and the above-mentioned epoxy resin containing borate ester bond are reacted, further and nano material with photo-thermal effect are reacted, and finally light curing and thermal post-curing are carried out respectively.The application constructs double dynamic covalent bond by Diels-Alder reaction and borate ester bond ester exchange reaction, simultaneously realizes photo-thermal conversion effect of carbon nanomaterial by Diels-Alder reaction functionalization, to prepare the epoxy resin that can be quickly and efficiently self-healed under near-infrared light irradiation by the synergistic effect of the two.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, and in particular relates to a near-infrared self-healing epoxy resin, its preparation method, and its application. Background Technology

[0002] With the depletion of global oil resources and the increasing demand for longer lifespans of epoxy resins, the need for self-healing epoxy resins is growing. Introducing dynamic covalent bonds within epoxy resins to achieve self-healing has become a current research hotspot. However, most current self-healing modified resins are based on single dynamic covalent bonds. For example, some literature reports the preparation of self-healing epoxy resins containing borate ester bonds based on the principle of borate ester bond transesterification. However, the strength of borate ester bonds is relatively weak, which affects the mechanical properties of epoxy resins to some extent. Furthermore, epoxy resins containing only single borate ester bonds require a self-healing reaction at 130-180℃, and prolonged high-temperature treatment can easily produce side reactions, reducing their repeated self-healing efficiency. Chinese patent application (CN103483605A) discloses a method for preparing reversibly covalently crosslinked epoxy resins using the Diels-Alder reaction, which causes the covalent crosslinking of epoxy resins to break at 100-150℃ and can be restored when the temperature is cooled to below 90℃. However, the reconstruction process of Diels-Alder bonds (DA bonds) is relatively slow and random, which reduces the repeatability of epoxy resin's self-healing efficiency.

[0003] Traditional dynamic covalent epoxy resins primarily rely on heat sources to trigger their self-healing process, resulting in long self-healing times, low self-healing efficiency, and even thermal deformation of the material. Carbon nanoparticles, with their photothermal conversion effect, can capture light signals and convert them into heat, enabling epoxy resins to rapidly self-heal under light irradiation. Summary of the Invention

[0004] To address at least some of the technical problems in the prior art, this invention provides a method for preparing epoxy resin that can rapidly and efficiently self-heal under near-infrared light irradiation by constructing dual dynamic covalent bonds through Diels-Alder (DA) reaction and borate ester exchange reaction, while simultaneously utilizing DA-functionalized carbon nanomaterials to achieve their photothermal conversion effect. Specifically, the invention includes the following:

[0005] A first aspect of the present invention provides a method for preparing a near-infrared self-healing epoxy resin, comprising the following steps:

[0006] (1) React epoxy resin and boric acid derivative to obtain epoxy resin containing borate ester bonds, react furan derivative and maleimide derivative to obtain mixed solution containing Diels-Alder bonds, and react the mixed solution with the epoxy resin containing borate ester bonds to obtain a double dynamic covalent epoxy resin containing borate ester bonds and Diels-Alder bonds.

[0007] (2) React the nanomaterial with photothermal effect with the double dynamic covalent epoxy resin to obtain the double dynamic covalent epoxy resin with photothermal conversion effect.

[0008] (3) The double dynamic covalent epoxy resin with photothermal conversion effect is subjected to photocuring and thermal post-curing respectively.

[0009] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, the molar ratio of the epoxy resin to the boric acid derivative is (1:0.8)-(1:1.2), the molar ratio of the furan derivative to the maleimide derivative is (1:0.9)-(1:1.3), and the molar ratio of the boric acid derivative to the furan derivative is (0.8:1)-(1.2:1).

[0010] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, the mass ratio of the nanomaterial and the dual dynamic covalent epoxy resin is (1:20)-(1:50).

[0011] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, the epoxy resin includes at least one of bisphenol A glycidyl ether, bisphenol F glycidyl ether, bisphenol S glycidyl ether, and alicyclic epoxy resin.

[0012] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, the boric acid derivative includes at least one of 3-carboxyphenylboronic acid, naphthaleneboronic acid, p-vinylphenylboronic acid, and methylphenylboronic acid.

[0013] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, the furan derivative includes at least one of 2-furanmethylamine, 2-furanethanol and 2,5-furandicarboxylic acid.

[0014] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, the maleimide derivative includes at least one selected from 1,6-bis(maleimide)hexane, 4,4'-methylenebis(N-phenylmaleimide), 1,8-bismaleimide diethylene glycol, and N,N'-1,3-phenylenebismaleimide.

[0015] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, the nanomaterial includes at least one of graphene, graphene oxide, single-walled carbon nanotubes, and multi-walled carbon nanotubes.

[0016] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin according to the present invention, in step (1), the epoxy resin and the boric acid derivative are reacted at 45-105°C for 1-5 hours.

[0017] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, in step (1), the furan derivative and the maleimide derivative are reacted at 55-95°C for 1-3 hours.

[0018] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin according to the present invention, in step (1), the mixed solution and the epoxy resin containing borate ester bonds are reacted at 55-95°C for 1-5 hours.

[0019] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin according to the present invention, in step (2), the nanomaterial and the double dynamic covalent epoxy resin are reacted at 55-95°C for 1-3 hours.

[0020] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, the reaction is carried out in a polar solvent.

[0021] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin of the present invention, the polar solvent includes at least one selected from ethanol, acetone, N,N'-dimethylformamide, N,N'-dimethylacetamide, and N-methylpyrrolidone.

[0022] In some embodiments, according to the method for preparing near-infrared self-healing epoxy resin according to the present invention, the photocuring conditions include curing at 800-1500 nm for 5-10 min, and the post-heat curing conditions include curing at 60-90 °C for 1-2 h.

[0023] In a second aspect, the present invention provides a near-infrared self-healing epoxy resin, which is prepared by the preparation method described in the present invention.

[0024] A third aspect of the present invention provides the application of the near-infrared self-healing epoxy resin described herein in coatings, adhesives, encapsulation materials, castings, molding materials or injection molding materials.

[0025] This invention constructs a dual-dynamic covalent epoxy resin through DA bonds and borate ester bonds. At 130-180℃, both DA bonds and borate ester bonds break simultaneously. The associated borate ester bonds undergo instantaneous bond exchange at the high temperature of 130-180℃, initially completing reconstruction. Subsequently, at 60-90℃, the dissociated DA bonds undergo a new DA reaction, and a small number of unreconstructed borate ester bonds undergo further bond exchange. The dual-dynamic covalent bonds are then reconstructed, achieving the self-healing properties of the epoxy resin.

[0026] This invention functionalizes carbon nanoparticles via a DA reaction by incorporating excess maleimide groups in the dual dynamic covalent bonds, grafting the carbon nanoparticles into these bonds. Leveraging the excellent photothermal conversion effect of the carbon nanoparticles, epoxy resin achieves complete self-healing within 90 seconds of near-infrared light irradiation, realizing rapid photo-induced self-healing properties. Furthermore, after two repeated self-healing cycles under near-infrared light, the epoxy resin of this invention still maintains a 90% self-healing efficiency in tensile strength, while simultaneously shortening the self-healing time and improving the self-healing efficiency.

[0027] In summary, this invention solves the problems of long self-healing time, low self-healing efficiency, and easy deformation of existing heat-source-based single dynamic covalent bond epoxy resins, and can be applied to the preparation of self-healing, self-repairing, and biodegradable epoxy resins. Attached Figure Description

[0028] Figure 1 The infrared spectrum of the double dynamic covalent epoxy resin containing DA bonds and borate ester bonds of the present invention is shown.

[0029] Figure 2 A schematic diagram of temperature monitoring during the self-healing process of the modified epoxy resin in Embodiment 1 of the present invention is shown.

[0030] Figure 3 A schematic diagram of temperature monitoring during the self-healing process of the modified epoxy resin in Embodiment 2 of the present invention is shown.

[0031] Figure 4 A schematic diagram of temperature monitoring during the self-healing process of the modified epoxy resin in Embodiment 3 of the present invention is shown.

[0032] Figure 5 The tensile strength of epoxy resin in the embodiments and comparative examples of the present invention is shown.

[0033] Figure 6 The self-healing efficiency of epoxy resin in the embodiments and comparative examples of the present invention is shown. Detailed Implementation

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that the upper and lower limits of the range and each intermediate value between them are specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0036] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0037] Preparation method

[0038] One aspect of the present invention provides a method for preparing a near-infrared self-healing epoxy resin, comprising the following steps:

[0039] (1) React epoxy resin and boric acid derivative to obtain epoxy resin containing borate ester bonds, react furan derivative and maleimide derivative to obtain mixed solution containing Diels-Alder bonds, and react the mixed solution with the epoxy resin containing borate ester bonds to obtain a double dynamic covalent epoxy resin containing borate ester bonds and Diels-Alder bonds.

[0040] (2) React the nanomaterial with photothermal effect with the double dynamic covalent epoxy resin to obtain the double dynamic covalent epoxy resin with photothermal conversion effect.

[0041] (3) The double dynamic covalent epoxy resin with photothermal conversion effect is subjected to photocuring and thermal post-curing respectively.

[0042] In a preferred embodiment, the molar ratio of the epoxy resin to the boric acid derivative is (1:0.8)-(1:1.2), preferably (1:0.9)-(1:1.2), even more preferably (1:0.9)-(1:1.1), further preferably (1:0.95)-(1:1.1), and more preferably (1:0.95)-(1:1.05), for example, 1:0.95, 1:0.96, 1:0.97, 1:0.98. The molar ratios of the furan derivative and the maleimide derivative are (1:0.99), (1:1.00), (1:1.01), (1:1.02), (1:1.03), (1:1.04), and (1:1.05); the molar ratio of the furan derivative to the maleimide derivative is (1:0.9)-(1:1.3), preferably (1:0.9)-(1:1.2), even more preferably (1:0.9)-(1:1.1), and more preferably (1:0.95)-(1:1.1), for example, 1:0.95, 1 The molar ratios of the boric acid derivative and the furan derivative are (0.8:1) to (1.2:1), preferably (0.9:1) to (1.2:1). Further preferred ratios are (0.9:1)-(1.1:1), and even more preferred ratios are (0.95:1)-(1.1:1), such as 0.95:1, 0.96:1, 0.97:1, 0.98:1, 0.99:1, 1.00:1, 1.01:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, 1.06:1, 1.07:1, 1.08:1, 1.09:1, and 1.10:1.

[0043] In a preferred embodiment, the mass ratio of the nanomaterial to the dual dynamic covalent epoxy resin is (1:20)-(1:50), preferably (1:21)-(1:49), even more preferably (1:22)-(1:48), further preferably (1:23)-(1:47), more preferably (1:24)-(1:46), even more preferably (1:25)-(1:45), for example 1:25, 1:27, 1:29, 1:31, 1:33, 1:35, 1:37, 1:39, 1:41, 1:43, 1:45.

[0044] In this invention, the epoxy resin includes bisphenol-type epoxy resin and / or alicyclic epoxy resin. The bisphenol-type epoxy resin includes, but is not limited to, one or a combination of bisphenol A glycidyl ether, bisphenol F glycidyl ether, bisphenol S glycidyl ether, bisphenol M epoxy resin, and bisphenol AD ​​epoxy resin; the alicyclic epoxy resin includes, but is not limited to, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylate. In a preferred embodiment, the epoxy resin is bisphenol A glycidyl ether. In another preferred embodiment, the epoxy resin is bisphenol F glycidyl ether. In yet another preferred embodiment, the epoxy resin is 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylate.

[0045] In this invention, the boric acid derivative includes one or a combination of 3-carboxyphenylboronic acid, naphthaleneboronic acid, p-vinylphenylboronic acid, and methylphenylboronic acid. In a preferred embodiment, the boric acid derivative is 3-carboxyphenylboronic acid. In another preferred embodiment, the boric acid derivative is p-vinylphenylboronic acid. In yet another preferred embodiment, the boric acid derivative is methylphenylboronic acid.

[0046] In this invention, the furan derivative includes at least one selected from 2-furanmethylamine, 2-furanethanol, and 2,5-furandicarboxylic acid. In a preferred embodiment, the furan derivative is 2-furanethanol. In another preferred embodiment, the furan derivative is 2-furanmethylamine. In yet another preferred embodiment, the furan derivative is 2,5-furandicarboxylic acid.

[0047] In this invention, the maleimide derivative comprises at least one selected from 1,6-bis(maleimide)hexane, 4,4'-methylenebis(N-phenylmaleimide), 1,8-bismaleimide diethylene glycol, and N,N'-1,3-phenylenebismaleimide. In a preferred embodiment, the maleimide derivative is N,N'-1,3-phenylenebismaleimide. In another preferred embodiment, the maleimide derivative is 1,6-bis(maleimide)hexane. In yet another preferred embodiment, the maleimide derivative is 4,4'-methylenebis(N-phenylmaleimide).

[0048] In this invention, the nanomaterial includes at least one selected from graphene, graphene oxide, single-walled carbon nanotubes, and multi-walled carbon nanotubes. In one preferred embodiment, the nanomaterial is graphene oxide. In another preferred embodiment, the nanomaterial is graphene. In yet another preferred embodiment, the nanomaterial is single-walled carbon nanotubes.

[0049] In step (1) of the present invention, the epoxy resin and the boric acid derivative are heated at 45-105°C, preferably 46-104°C, even more preferably 47-103°C, further preferably 48-102°C, more preferably 49-101°C, and even more preferably 50-100°C, for example 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 7... The epoxy resin and the boric acid derivative are reacted at 6℃, 78℃, 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃, 96℃, 98℃, and 100℃ for 1-5 hours (e.g., 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, and 5.0 hours). In a preferred embodiment, the epoxy resin and the boric acid derivative are reacted at 50℃ for 5 hours. In another preferred embodiment, the epoxy resin and the boric acid derivative are reacted at 80℃ for 3 hours. In yet another preferred embodiment, the epoxy resin and the boric acid derivative are reacted at 100℃ for 1 hour.

[0050] In step (1) of the present invention, the furan derivative and the maleimide derivative are reacted at 55-95°C, preferably 56-94°C, even more preferably 57-93°C, further preferably 58-92°C, more preferably 59-91°C, and even more preferably 60-90°C, for example at 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C, and 90°C for 1-3 hours (e.g., 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, and 3.0 hours). In a preferred embodiment, the furan derivative and the maleimide derivative are reacted at 60°C for 3 hours. In another preferred embodiment, the furan derivative and the maleimide derivative are reacted at 80°C for 2 hours. In yet another preferred embodiment, the furan derivative and the maleimide derivative are reacted at 90°C for 1 hour.

[0051] In step (1) of the present invention, the mixed solution and the epoxy resin containing borate ester bonds are reacted at 55-95°C, preferably 56-94°C, even more preferably 57-93°C, further preferably 58-92°C, more preferably 59-91°C, and more preferably 60-90°C, for example at 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C, and 90°C for 1-5 hours (for example, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, and 5.0 hours). In one preferred embodiment, the mixed solution and the borate ester-containing epoxy resin are reacted at 60°C for 5 hours. In another preferred embodiment, the mixed solution and the borate ester-containing epoxy resin are reacted at 80°C for 3 hours. In a preferred embodiment, the mixed solution and the borate ester-containing epoxy resin are reacted at 90°C for 1 hour.

[0052] In step (2) of the present invention, the nanomaterial and the dual dynamic covalent epoxy resin are reacted at 55-95°C, preferably 56-94°C, even more preferably 57-93°C, further preferably 58-92°C, more preferably 59-91°C, and even more preferably 60-90°C, for example at 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C, and 90°C for 1-3 hours (for example, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, and 3.0 hours).

[0053] In a preferred embodiment, the reaction is carried out in a polar solvent, which includes, but is not limited to, one or a combination of ethanol, acetone, N,N'-dimethylformamide, N,N'-dimethylacetamide, and N-methylpyrrolidone. In one preferred embodiment, the polar solvent is N,N-dimethylformamide. In another preferred embodiment, the polar solvent is N,N-dimethylacetamide. In yet another preferred embodiment, the polar solvent is N-methylpyrrolidone.

[0054] In a preferred embodiment, the photocuring includes wavelengths of 800-1500 nm (e.g., 800, 820, 840, 860, 880, 900, 920, 940, 960, 980, 1000, 1020, 1040, 1060, 1080, 1100, 1120, 1140, 1160, 1180, 1200, 1220, 1240, 1260, 1280, 1300, 1320, 1340, 1360, 1380, 14...). The photocuring process involves curing at 800 nm for 5-10 minutes (e.g., 5, 6, 7, 8, 9, 10 minutes) and post-curing at 60-90 °C for 1-2 hours (e.g., 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 hours). In a preferred embodiment, the photocuring conditions are curing at 800 nm for 10 minutes and post-curing at 60 °C for 2 hours. In another preferred embodiment, the photocuring conditions are curing at 1000 nm for 8 minutes and post-curing at 80 °C for 1.5 hours. In yet another preferred embodiment, the photocuring conditions are curing under 1500nm light for 5 minutes, and the post-heat curing conditions are curing at 90°C for 1 hour.

[0055] Near-infrared self-healing epoxy resin

[0056] In one aspect, the present invention provides a near-infrared self-healing epoxy resin, which is prepared by the preparation method described in the present invention.

[0057] In this invention, "self-healing" is sometimes also called "self-repair," referring to the ability of damaged epoxy resin to self-repair or return to its pre-damage state under light irradiation conditions (e.g., irradiation with near-infrared light at 700-2500 nm for 60-120 s). The self-healing performance can be determined by measuring its healing rate. The testing of the self-healing performance of epoxy resin can be performed using methods known in the art, and there are no particular limitations on these methods.

[0058] application

[0059] One aspect of the present invention provides the application of the near-infrared self-healing epoxy resin described herein in coatings, adhesives, encapsulation materials, castings, molding materials or injection molding materials.

[0060] In this invention, examples of coatings include, but are not limited to, building protective coatings (e.g., protective coatings for walls, roofs, and floors), protective coatings for laminated wood, outdoor coatings, heavy-duty protective coatings, and anti-corrosion layers for industrial equipment. Examples of adhesive materials include, but are not limited to, concrete reinforcing adhesives and steel structure connection adhesives. Examples of encapsulation materials include, but are not limited to, semiconductor encapsulation materials, integrated circuit encapsulation materials, and electronic component encapsulation materials. Examples of casting materials include, but are not limited to, bearing casting materials and gear casting materials. Examples of molding materials include, but are not limited to, electronic product molds and automotive part molds. Examples of injection molding materials include, but are not limited to, injection molding molds.

[0061] Example 1

[0062] The following shows the preparation method and performance testing of near-infrared self-healing epoxy resin.

[0063] 1. Preparation method

[0064] (1) Design and preparation of epoxy resin with dual dynamic covalent bonds: Bisphenol A type glycidyl ether and 3-carboxyphenylboronic acid were added to N,N-dimethylformamide at a molar ratio of 1:1 and reacted at 50℃ for 5h to obtain epoxy resin containing borate ester bonds; 2-furan methanol and N,N'-1,3-phenylenebismaleimide were added to N,N-dimethylformamide at a molar ratio of 1:1.02 and reacted at 60℃ for 3h to obtain a mixed solution containing DA bonds. The two solutions were reacted at 60℃ for 5h to obtain epoxy resin with dual dynamic covalent bonds containing borate ester bonds and DA bonds.

[0065] (2) Preparation of dual dynamic covalent epoxy resin with photothermal conversion effect: 0.05g of graphene oxide was dispersed in N,N-dimethylformamide to obtain a suspension, and 25g of dual dynamic covalent epoxy resin was added. The graphene oxide was reacted with N,N'-1,3-phenylenebismaleimide in the dual dynamic covalent epoxy resin at 60℃ for 3h to obtain dual dynamic covalent epoxy resin with photothermal conversion effect.

[0066] (3) Photothermal synergistic curing of epoxy resin: Utilizing the photothermal conversion effect of graphene oxide in epoxy resin and the dual reversible characteristics of dual dynamic covalent bonds, the epoxy resin was prepared by curing under 800nm ​​light for 10min and then heat curing at 60℃ for 2h.

[0067] (4) Preparation of near-infrared self-healing epoxy resin: The epoxy resin obtained in step (3) is subjected to a cross-shaped scratch treatment. The epoxy resin with damaged surface is placed under 800nm ​​light for 90s to obtain self-healing epoxy resin.

[0068] 2. Performance Testing

[0069] Two low-speed impact tests were conducted on the epoxy resin. After the damaged epoxy resin was self-healed for 90 seconds under 800nm ​​light, a tensile test was performed. The tensile strength after the first and second self-healing was recorded and the self-healing efficiency was calculated.

[0070] Example 2

[0071] The following shows the preparation method and performance testing of near-infrared self-healing epoxy resin.

[0072] 1. Preparation method

[0073] (1) Design and preparation of epoxy resin with dual dynamic covalent bonds: Bisphenol F glycidyl ether and p-vinylphenylboronic acid were added to N,N-dimethylacetamide at a molar ratio of 1:1.02 and reacted at 80°C for 3 h to obtain epoxy resin containing borate ester bonds; 2-furanmethylamine and 1,6-bis(maleimide)hexane were added to N,N-dimethylacetamide at a molar ratio of 1:1.05 and reacted at 80°C for 2 h to obtain a mixed solution containing DA bonds. The two solutions were reacted at 80°C for 3 h to obtain epoxy resin with dual dynamic covalent bonds containing borate ester bonds and DA bonds.

[0074] (2) Preparation of dual dynamic covalent epoxy resin with photothermal conversion effect: 0.1g of graphene was dispersed in N,N-dimethylacetamide to obtain a suspension, and 25g of dual dynamic covalent epoxy resin was added. The graphene was reacted with 1,6-bis(maleimide)hexane in the dual dynamic covalent epoxy resin at 80℃ for 2h to obtain dual dynamic covalent epoxy resin with photothermal conversion effect.

[0075] (3) Photothermal synergistic curing of epoxy resin: Utilizing the photothermal conversion effect of graphene oxide in epoxy resin and the dual reversible characteristics of dual dynamic covalent bonds, the epoxy resin was prepared by curing under 1000nm light for 8min and then heat curing at 80℃ for 1.5h.

[0076] (4) Preparation of near-infrared self-healing epoxy resin: The epoxy resin obtained in step (3) is subjected to a cross-shaped scratch treatment. The epoxy resin with damaged surface is placed under 1000nm light for 60s to obtain self-healing epoxy resin.

[0077] 2. Performance Testing

[0078] Two low-speed impact tests were conducted on the epoxy resin. After the damaged epoxy resin was self-healed for 60 seconds under 1000nm light, a tensile test was performed. The tensile strength after the first and second self-healing was recorded and the self-healing efficiency was calculated.

[0079] Example 3

[0080] The following shows the preparation method and performance testing of near-infrared self-healing epoxy resin.

[0081] 1. Preparation method

[0082] (1) Design and preparation of epoxy resin with dual dynamic covalent bonds: 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexylcarboxylate (ECC) and methylphenylboronic acid were added to N-methylpyrrolidone at a molar ratio of 1:1.05 and reacted at 100℃ for 1 h to obtain epoxy resin containing borate ester bonds; 2,5-furandicarboxylic acid and 4,4'-methylenebis(N-phenylmaleimide) were added to N-methylpyrrolidone at a molar ratio of 1:1.1 and reacted at 90℃ for 1 h to obtain a mixed solution containing DA bonds. The two solutions were reacted at 90℃ for 1 h to obtain epoxy resin with dual dynamic covalent bonds containing borate ester bonds and DA bonds.

[0083] (2) Preparation of dual dynamic covalent epoxy resin with photothermal conversion effect: 0.125g of single-walled carbon nanotubes were dispersed in N-methylpyrrolidone to obtain a suspension, and 25g of dual dynamic covalent epoxy resin was added. The single-walled carbon nanotubes were reacted with 4,4'-methylenebis(N-phenylmaleimide) in the dual dynamic covalent epoxy resin at 90℃ for 1h to obtain dual dynamic covalent epoxy resin with photothermal conversion effect.

[0084] (3) Preparation of photothermal synergistic curing epoxy resin: Utilizing the photothermal conversion effect of graphene oxide in epoxy resin and the dual reversible characteristics of dual dynamic covalent bonds, the epoxy resin was prepared by curing under 1500nm light for 5min and then heat curing at 90℃ for 1h.

[0085] (4) Preparation of near-infrared self-healing epoxy resin: The epoxy resin obtained in step (3) is subjected to a cross-shaped scratch treatment. The epoxy resin with damaged surface is placed under 1500nm light for 30s to obtain self-healing epoxy resin.

[0086] 2. Performance Testing

[0087] Two low-speed impact tests were conducted on the epoxy resin. After the damaged epoxy resin was self-healed for 30 seconds under 1500nm light, a tensile test was performed. The tensile strength after the first and second self-healing was recorded and the self-healing efficiency was calculated.

[0088] Comparative Example 1

[0089] The following shows the preparation method and performance testing of self-healing epoxy resin.

[0090] 1. Preparation method

[0091] (1) Design and preparation of epoxy resin containing borate ester bonds: Bisphenol A type glycidyl ether and 3-carboxyphenylboronic acid were added to N,N-dimethylformamide at a molar ratio of 1:1.02 and reacted at 80℃ for 3h to obtain epoxy resin containing borate ester bonds.

[0092] (2) Preparation of self-healing epoxy resin: The borate ester bond epoxy resin obtained in step (1) is subjected to a thermocuring reaction at 80°C for 12 hours to prepare self-healing epoxy resin.

[0093] 2. Performance Testing

[0094] A scratch test was conducted on the epoxy resin surface. The damaged epoxy resin was placed at 150°C until it was completely self-healed, and the self-healing time was recorded. Two low-speed impact tests were conducted on the epoxy resin. After the damaged epoxy resin was completely self-healed at 150°C, a tensile test was conducted. The tensile strength after the first and second self-healing was recorded, and the self-healing efficiency was calculated.

[0095] Comparative Example 2

[0096] The following shows the preparation method and performance testing of self-healing epoxy resin.

[0097] 1. Preparation method

[0098] (1) Design and preparation of DA bond epoxy resin: Bisphenol A type glycidyl ether and 2-furan methylamine were added to N,N-dimethylformamide at a molar ratio of 1:1.02 and reacted at 80℃ for 3h; N,N'-1,3-phenylenebismaleimide was dissolved in N,N-dimethylformamide and the above solution was reacted at 80℃ for 3h, wherein the molar ratio of 2-furan methylamine to N,N'-1,3-phenylenebismaleimide was 1:1.02, and epoxy resin containing DA bond was obtained.

[0099] (2) Preparation of self-healing epoxy resin: The DA bond epoxy resin obtained in step (1) was subjected to a thermocuring reaction at 80°C for 36 hours to prepare self-healing epoxy resin.

[0100] 2. Performance Testing

[0101] A scratch test was conducted on the epoxy resin surface. The damaged epoxy resin was placed at 150℃ for 10 minutes and at 80℃ until it was completely self-healed, and the self-healing time was recorded. Two low-speed impact tests were conducted on the epoxy resin. After the damaged epoxy resin was completely self-healed under the above conditions, a tensile test was conducted. The tensile strength after the first and second self-healing was recorded and the self-healing efficiency was calculated.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a near-infrared self-healing epoxy resin, characterized in that, Includes the following steps: (1) React epoxy resin and boric acid derivative at 45-105℃ for 1-5 h to obtain epoxy resin containing boric acid ester bonds, react furan derivative and maleimide derivative at 55-95℃ for 1-3 h to obtain mixed solution containing Diels-Alder bonds, react the mixed solution and the epoxy resin containing boric acid ester bonds at 55-95℃ for 1-5 h to obtain a double dynamic covalent epoxy resin containing boric acid ester bonds and Diels-Alder bonds; (2) React the photothermal nanomaterial and the dual-dynamic covalent epoxy resin at 55-95℃ for 1-3h to obtain the photothermal conversion effect dual-dynamic covalent epoxy resin; the nanomaterial is graphene, graphene oxide, single-walled or multi-walled carbon nanotubes. (3) The double dynamic covalent epoxy resin with photothermal conversion effect is subjected to photocuring and thermal post-curing respectively.

2. The method for preparing near-infrared self-healing epoxy resin according to claim 1, characterized in that, The molar ratio of the epoxy resin to the boric acid derivative is (1:0.8)-(1:1.2), the molar ratio of the furan derivative to the maleimide derivative is (1:0.9)-(1:1.3), and the molar ratio of the boric acid derivative to the furan derivative is (0.8:1)-(1.2:1).

3. The method for preparing near-infrared self-healing epoxy resin according to claim 1, characterized in that, The mass ratio of the nanomaterial to the dual dynamic covalent epoxy resin is (1:20)-(1:50).

4. The method for preparing near-infrared self-healing epoxy resin according to claim 1, characterized in that, The epoxy resin includes bisphenol type epoxy resin and / or alicyclic epoxy resin.

5. The method for preparing near-infrared self-healing epoxy resin according to claim 1, characterized in that, The boric acid derivatives include at least one of 3-carboxyphenylboronic acid, naphthaleneboronic acid, p-vinylphenylboronic acid, and methylphenylboronic acid.

6. The method for preparing near-infrared self-healing epoxy resin according to claim 1, characterized in that, The furan derivatives include at least one of 2-furanmethylamine, 2-furanethanol, and 2,5-furandicarboxylic acid.

7. The method for preparing near-infrared self-healing epoxy resin according to claim 1, characterized in that, The maleimide derivatives include at least one of 1,6-bis(maleimide)hexane, 4,4'-methylenebis(N-phenylmaleimide), 1,8-bismaleimide diethylene glycol, and N,N'-1,3-phenylenebismaleimide.

8. The method for preparing near-infrared self-healing epoxy resin according to claim 1, characterized in that, The reaction is carried out in a polar solvent.

9. The method for preparing near-infrared self-healing epoxy resin according to claim 8, characterized in that, The polar solvent includes at least one of ethanol, acetone, N,N'-dimethylformamide, N,N'-dimethylacetamide, and N-methylpyrrolidone.

10. The method for preparing the near-infrared self-healing epoxy resin according to claim 1, characterized in that, The photocuring conditions include curing at 800-1500 nm for 5-10 min, and the post-thermal curing conditions include curing at 60-90℃ for 1-2 h.

11. A near-infrared self-healing epoxy resin, characterized in that, It is prepared according to any one of claims 1-10.

12. The application of the near-infrared self-healing epoxy resin according to claim 11 in coatings, adhesives, encapsulation materials, castings, molding materials or injection molding materials.

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