A monomer for constructing a supramolecular polymer network, a toughened epoxy resin comprising the same, and a preparation method and applications thereof

Abstract

The application provides a monomer for constructing a supramolecular polymer network, a toughened epoxy resin containing the monomer, and a preparation method and application thereof, and belongs to the technical field of supramolecular polymers.The monomer is composed of an ethoxy columnar arene and a cyano long alkyl chain, and forms a supramolecular polymer network through self-assembly; an epoxy resin monomer and a curing agent polyether amine are cured to form an epoxy resin network; and the supramolecular polymer network and the epoxy resin network are intertwined to obtain a toughened epoxy resin based on a double-network structure.The toughened epoxy resin dissipates energy through dissociation and recombination of host-guest interaction in the supramolecular polymer network, so that the strength and toughness are simultaneously improved, the mechanical properties of the epoxy resin are enhanced, and the toughened epoxy resin has great application potential in the field of high-performance polymer materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of supramolecular polymers, and particularly relates to a monomer for constructing a supramolecular polymer network, a toughened epoxy resin containing the monomer, and a preparation method and application thereof. BACKGROUND

[0002] Epoxy resin is an important thermosetting polymer material, which has been widely used in aerospace, electronic packaging and composite materials industries, mainly due to its excellent mechanical properties, outstanding chemical stability and excellent adhesion. Despite these advantages, the highly cross-linked covalent structure of epoxy resin poses a major challenge: the ability of epoxy resin to absorb and dissipate energy is inherently limited, resulting in insufficient toughness. To address this issue, researchers have explored various traditional toughening methods, including the incorporation of liquid crystal polymers, rubbers, core-shell particles and nanomaterials, which have become one of the key research areas in materials science. Current methods have achieved certain success in improving the toughness of epoxy resin, but there are still some aspects that can be further deepened, such as material strength, thermal stability and optimization of preparation process. Therefore, exploring new toughening methods that can both improve toughness and strength is a promising direction.

[0003] Double network structure has a significant effect on enhancing toughness and has attracted widespread attention in the field of materials science, especially in the study of hydrogels. Double network structure is usually composed of two different polymer networks, one of which is a strong rigid network that helps to enhance the strength of the material, and the other is a weak network that is responsible for effectively dissipating energy. This design allows the weak network to break when the material is subjected to external force, dispersing stress and dissipating energy, thereby significantly improving the toughness of the material. Supramolecular polymer network is a classic form of weak network, which is favored for its dynamic reversibility and self-assembly ability. These networks can respond to external stimuli through the reorganization and dissociation of non-covalent interactions, effectively dissipating energy and thereby improving the strength and toughness of the material.

[0004] Therefore, how to construct an epoxy resin system with a double network structure that has good toughening effect is the focus of research in the field. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a monomer for constructing a supramolecular polymer network, and a toughened epoxy resin based on a double network structure, as well as a preparation method and application thereof. The present application introduces a supramolecular polymer network into the epoxy resin system by using a monomer that can self-assemble to form a supramolecular polymer network, successfully constructing a toughened epoxy resin based on a double network structure, and providing a new idea for the design and construction of functional polymer materials.

[0006] To achieve the above object, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a monomer for constructing a supramolecular polymer network, which has the following structure:

[0008] .

[0009] In a second aspect, the present application provides a preparation method of the monomer for constructing a supramolecular polymer network, which comprises the following steps:

[0010] (1) 1,4-diethoxybenzene, paraformaldehyde and boron trifluoride etherate are reacted to obtain compound 1, and the reaction formula is as follows:

[0011] ;

[0012] (2) Compound 1 is reacted with boron tribromide to remove ethyl to obtain compound 2, and the reaction formula is as follows:

[0013] ;

[0014] (3) 2,5-dihydroxy terephthalic acid diethyl ester is reacted with a halogen heptane nitrile compound to obtain compound 3, and the reaction formula is as follows:

[0015] ;

[0016] X is halogen; the halogen can be F, Cl, Br or I;

[0017] (4) Compound 3 is hydrolyzed to obtain compound 4, and the reaction formula is as follows:

[0018] ;

[0019] (5) Compound 4 is reacted with triethylene glycol to obtain compound 5, and the reaction formula is as follows:

[0020] ;

[0021] (6) Compound 5 is reacted with 4-toluene sulfonyl chloride to obtain compound 6, and the reaction formula is as follows:

[0022] ;

[0023] (7) Compound 2 is reacted with compound 6 to obtain the monomer for constructing a supramolecular polymer network, and the reaction formula is as follows:

[0024]

[0025]

[0026] .

[0027] Preferably, the molar ratio of 1,4-diethoxybenzene to paraformaldehyde in step (1) is 1: (3.0-3.5), for example 1:3.0, 1:3.1, 1:3.2, 1:3.3, 1:3.4 or 1:3.5.

[0028] Preferably, the molar ratio of boron trifluoride diethyl ether to 1,4-diethoxybenzene in step (1) is 1:1.

[0029] Preferably, the reaction in step (1) is carried out at room temperature (15-30°C, for example 15°C, 20°C, 25°C, 28°C or 30°C), and the reaction time is 30 min.

[0030] Preferably, the reaction in step (1) is carried out in a solvent selected from dichloromethane and / or trichloromethane.

[0031] In the present application, after the reaction in step (1) is completed, water is added to quench the reaction, extraction is performed, the organic phase is dried and concentrated, and column chromatography is used for purification to obtain compound 1. The purification is carried out by silica gel column chromatography, and the eluent for the silica gel column chromatography is a mixture of petroleum ether and ethyl acetate in a volume ratio of 7:1.

[0032] Preferably, the molar ratio of compound 1 to boron tribromide in step (2) is (1-1.5):1, for example 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1.

[0033] Preferably, the boron tribromide in step (2) is added dropwise to the reaction system containing compound 1 under ice bath.

[0034] Preferably, the reaction in step (2) is carried out at a temperature of 0°C for 6 hours.

[0035] Preferably, the reaction in step (2) is carried out in a solvent selected from dichloromethane and / or trichloromethane.

[0036] In the present application, after the reaction in step (2) is completed, deionized water is added to quench the reaction, extraction is performed, the organic phase is dried and concentrated, and column chromatography is used for purification to obtain compound 2. The purification is carried out by silica gel column chromatography, and the eluent for the silica gel column chromatography is a mixture of petroleum ether and ethyl acetate in a volume ratio of 7:1.

[0037] Preferably, the molar ratio of diethyl 2,5-dihydroxyterephthalate to halogen heptyl cyanide in step (3) is 1 : (3.0-4.0), such as 1 :3.0, 1 :3.2, 1 :3.4, 1 :3.5, 1 :3.6, 1 :3.8, or 1 :4.0, etc.

[0038] Preferably, the reaction in step (3) is carried out in the presence of a basic substance selected from potassium carbonate and / or sodium carbonate.

[0039] Preferably, the molar ratio of the basic substance to diethyl 2,5-dihydroxyterephthalate is (3.0-4.0): 1, such as 3.0: 1, 3.2: 1, 3.4: 1, 3.5: 1, 3.6: 1, 3.8: 1, or 4.0: 1, etc.

[0040] Preferably, the reaction in step (3) is carried out under reflux, and the reaction time is 12 hours.

[0041] Preferably, the reaction in step (3) is carried out in an organic solvent selected from N,N-dimethylformamide,

[0042] In the present application, after the reaction in step (3) is completed, filtration and concentration are carried out, and after extraction, the organic phase is dried and concentrated, and compound 3 is obtained by column chromatography purification. The purification is carried out by silica gel column chromatography, and the eluent for silica gel column chromatography is a mixture of dichloromethane and methanol in a volume ratio of 200: 1.

[0043] Preferably, the hydrolysis reaction in step (4) is carried out in an ethanol solution of sodium hydroxide.

[0044] Preferably, the molar ratio of compound 3 to sodium hydroxide is 1 : (3.0-3.5), such as 1 :3.0, 1 :3.1, 1 :3.2, 1 :3.3, 1 :3.4, or 1 :3.5.

[0045] Preferably, the hydrolysis reaction in step (4) is carried out under reflux, and the hydrolysis reaction time is 12 hours.

[0046] Preferably, after the reaction in step (4) is completed, the system is adjusted to be acidic.

[0047] In the present application, after the reaction in step (4) is completed, concentration is carried out, and after dissolution in deionized water, the pH is adjusted to 4 with an HCl solution to obtain compound 4.

[0048] Preferably, the molar ratio of compound 4 to trioxa-ethanediol in step (5) is 1 : (3.0-3.5), such as 1 :3.0, 1 :3.1, 1 :3.2, 1 :3.3, 1 :3.4, or 1 :3.5.

[0049] Preferably, the reaction in step (5) is carried out in the presence of a basic substance, which is 4-dimethylaminopyridine (DMAP).

[0050] Preferably, the molar ratio of 4-dimethylaminopyridine to compound 4 is (2.0-2.1): 1.

[0051] Preferably, the reaction in step (5) is carried out in the presence of a catalyst of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDCl).

[0052] Preferably, the molar ratio of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride to compound 4 is (2.0-2.1): 1.

[0053] Preferably, the reaction in step (5) is carried out under nitrogen protection.

[0054] Preferably, the temperature of the reaction in step (5) is 25°C, and the reaction time is 12 h.

[0055] Preferably, the reaction in step (5) is carried out in a solvent selected from dichloromethane and / or trichloromethane.

[0056] In the present application, after the reaction in step (5) is completed, deionized water is added, and the organic phase is extracted with dichloromethane, dried and concentrated, and then purified by column chromatography to obtain compound 5. The purification is carried out by silica gel column chromatography, and the eluent for silica gel column chromatography is a mixture of petroleum ether and acetone in a volume ratio of 2:1.

[0057] Preferably, the molar ratio of compound 5 to 4-toluenesulfonyl chloride in step (6) is 1:(4-4.1).

[0058] Preferably, the reaction in step (6) is carried out in the presence of a basic substance selected from potassium hydroxide and / or sodium hydroxide.

[0059] Preferably, the molar ratio of the basic substance to compound 5 is (3.0-3.2): 1, for example 3.0:1, 3.1:1 or 3.2:1.

[0060] Preferably, the reaction in step (6) is carried out in a solvent, which is a mixture of water and tetrahydrofuran.

[0061] Preferably, the volume ratio of water to tetrahydrofuran is 1:4.0.

[0062] Preferably, the temperature of the reaction in step (6) is 0°C, and the reaction time is 6 h.

[0063] After the reaction in step (6) is completed, the organic phase is concentrated, extracted, dried and concentrated, and column chromatography is used for purification to obtain compound 6. The purification is performed by using silica gel column chromatography, and the eluent of the silica gel column chromatography is a mixture of petroleum ether and acetone in a volume ratio of 2:1.

[0064] Preferably, the molar ratio of compound 2 to compound 5 in step (7) is (3.0-3.2):1.

[0065] Preferably, the reaction in step (7) is performed in the presence of a basic substance selected from cesium carbonate,

[0066] Preferably, the molar ratio of the basic substance to compound 5 is (3.0-3.2):1, for example 3.0:1, 3.1:1 or 3.2:1.

[0067] Preferably, compound 6 is added dropwise to the reaction system containing compound 2 at 0°C in step (7).

[0068] Preferably, the reaction in step (7) is performed under reflux, and the reaction time is 2-3 days.

[0069] Preferably, the reaction in step (7) is performed in a solvent selected from N,N-dimethylformamide.

[0070] In the present application, after the reaction in step (7) is completed, the reaction system is filtered and concentrated, and column chromatography is used for purification to obtain the monomer; the purification is performed by using silica gel column chromatography, and the eluent of the silica gel column chromatography is a mixture of petroleum ether and ethyl acetate in a volume ratio of 1:2.

[0071] In another aspect, the present application provides a toughened epoxy resin, and the raw materials for preparing the toughened epoxy resin include an epoxy resin, a curing agent and a monomer for constructing a supramolecular polymer network as described above.

[0072] In the present application, the monomer for constructing a supramolecular polymer network is used for toughening an epoxy resin, and the monomer is composed of an ethoxy columnar arene and a cyano long alkyl chain, and a supramolecular polymer network is formed by self-assembly, and an epoxy resin monomer and a curing agent are ring-opening cured to form an epoxy resin network; the above-mentioned supramolecular polymer network and the epoxy resin network are intertwined to obtain a toughened epoxy resin based on a double network structure. The toughened epoxy resin dissipates energy through the dissociation and recombination of the host-guest interaction in the supramolecular polymer network, thereby realizing the synchronous improvement of strength and toughness, not only enhancing the mechanical properties of the epoxy resin, but also providing a novel high-performance high-toughness material design strategy.

[0073] Preferably, the curing agent is selected from polyether amine curing agents.

[0074] Preferably, the weight ratio of the epoxy resin to the curing agent is 1.25:1.

[0075] Preferably, the content of the monomer for building supramolecular polymer network is 1-10%, such as 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, based on the total weight of the toughened epoxy resin being 100%.

[0076] In another aspect, the present application provides a method for preparing the toughened epoxy resin as described above, comprising the following steps:

[0077] The epoxy resin, the curing agent and the monomer for building supramolecular polymer network are put into a solvent to obtain a precursor solution, and then the precursor solution is cured to obtain the toughened epoxy resin.

[0078] Preferably, the solvent is selected from trichloromethane and / or dichloromethane.

[0079] Preferably, the precursor solution is subjected to freeze-drying before curing, and then the obtained liquid is subjected to ultrasonic treatment, and then curing.

[0080] In the present application, the freeze-drying is placing in liquid nitrogen, vacuumizing for 30 minutes under vacuum to remove air and trichloromethane in the mixture, and then the obtained liquid is injected into a prepared glass mold, ultrasonic treatment for 3 minutes, removing small air bubbles with a capillary tube, and then placing in a blast oven for curing.

[0081] Preferably, the temperature control of the curing is 30℃ for 2h; then increasing the temperature to 60℃ for 2h; and then increasing the temperature to 90℃ for 8h.

[0082] In the present application, the toughened epoxy resin is obtained after cooling and demolding after the curing is completed.

[0083] In another aspect, the present application provides the use of the toughened epoxy resin as described above in the synthesis of functional polymer materials.

[0084] Preferably, the functional polymer material is an elastomer.

[0085] Compared with the prior art, the present application has the following beneficial effects:

[0086] The monomer for constructing the supramolecular polymer network of the present application is composed of ethoxy columnar arene and cyano long alkyl chain, and forms a supramolecular polymer network through self-assembly; the monomer is used for toughening epoxy resin, and epoxy resin monomer and curing agent are cured to form an epoxy resin network; the supramolecular polymer network and the epoxy resin network are intertwined to obtain a toughened epoxy resin based on a double network structure. The toughened epoxy resin dissipates energy through dissociation and recombination of host-guest interaction in the supramolecular polymer network, thereby realizing synchronous improvement of strength and toughness, and not only endows the epoxy resin with a unique topological structure, but also enhances the mechanical properties of the epoxy resin, and has an application potential that cannot be ignored in the field of high-performance polymer materials. BRIEF DESCRIPTION OF DRAWINGS

[0087] Figure 1 H NMR chart of compound 1. 1 H NMR chart of compound 1.

[0088] Figure 2 H NMR chart of compound 2. 1 H NMR chart of compound 2.

[0089] Figure 3 H NMR chart of compound 3. 1 H NMR chart of compound 3.

[0090] Figure 4 H NMR chart of compound 4. 1 H NMR chart of compound 4.

[0091] Figure 5 H NMR chart of compound 5. 1 H NMR chart of compound 5.

[0092] Figure 6 H NMR chart of compound 6. 1 H NMR chart of compound 6.

[0093] Figure 7 H NMR chart of compound H2G2-1. 1 H NMR chart of compound H2G2-1.

[0094] Figure 8 Tensile stress-strain curves of DEP-0, DEP-1, DEP-2, DEP-3 and DEP-4 in the examples.

[0095] Figure 9 Cyclic tensile test curves of DEP-0 and DEP-3 in the examples.

[0096] Figure 10 TGA curves of DEP-0, DEP-1, DEP-2, DEP-3 and DEP-4 in the examples. DETAILED DESCRIPTION

[0097] The technical solutions of the present application are further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations on the present application.

[0098] Example 1

[0099] In this embodiment, a monomer H2G2-1 for constructing a supramolecular polymer network is provided, and the preparation method thereof comprises the following steps:

[0100] 1. Synthesis of compound 1

[0101]

[0102] Dissolve 1,4-diethoxybenzene (10.0 g, 60 mmol) and paraformaldehyde (5.42 g, 180.6 mmol) in dichloromethane (130 mL). Slowly add BF3-Et2O (7.43 mL, 60.2 mmol) to the reaction mixture at room temperature. After 30 minutes, quench the reaction by adding 50 mL of water. Extract with dichloromethane, and purify by column chromatography in petroleum ether / ethyl acetate (7:1, v / v) to obtain compound 1 (6.95 g, 65%).

[0103] The structure of the synthesized compound 1 is characterized, and an appropriate amount of the final product is weighed in a nuclear magnetic tube, dissolved in deuterated chloroform, and tested at 25°C using a nuclear magnetic resonance instrument. Figure 1 The nuclear magnetic resonance spectrum of compound 1 is as follows: Figure 1 It can be seen that the chemical shifts, integrals, and coupling splitting of each hydrogen are consistent with the target molecule, indicating that the target product is obtained, and the spectrum has no impurity peak, proving that the product has high purity.

[0104] The nuclear magnetic hydrogen spectrum data of compound 1 are as follows: 1 H NMR (CDCl3, 600 MHz, 298K) δ (ppm): 6.72(s, 10H), 3.82 (q, J = 7 Hz, 20H), 3.77 (s, 10H), 1.25 (t, J = 7 Hz, 30H).

[0105] 2. Synthesis of compound 2

[0106]

[0107] Compound 1 (1.00 g, 1.12 mmol) was dissolved in 30 mL of dichloromethane, stirred in ice bath for 10 minutes, then slowly added 2 mol / L BBr3dichloromethane solution (0.5 mL, 1 mmol). After 1 h at room temperature, the reaction was quenched by adding 30 mL of deionized water. After 3 times of dichloromethane extraction, dried with anhydrous MgSO4, spin dried with a rotary evaporator, and purified by column chromatography with petroleum ether / ethyl acetate (7:1, v / v) as eluent to obtain compound 2.

[0108] The structure of the synthesized compound 2 was characterized, and an appropriate amount of the final product was weighed into a nuclear magnetic tube, dissolved in deuterated chloroform, and tested at 25°C using a nuclear magnetic resonance instrument. Figure 2 The nuclear magnetic resonance spectrum of compound 2 is shown in Figure 1. Figure 2 It can be seen that the chemical shifts, integrals, and coupling splitting of each hydrogen are consistent with the target molecule, indicating that the target product is obtained, and the spectrum has no impurity peak, proving that the product reaches a high purity.

[0109] The nuclear magnetic hydrogen spectrum data of compound 2 are as follows: 1 H NMR (CDCl3, 600 MHz, 298K) δ (ppm): 6.90(s, 1H), 6.80 (s, 1H), 6.69 (d, J = 12 Hz, 2H), 6.64 (d, J = 8 Hz, 3H), 6.57−6.53 (m, 3H), 6.49 (s, 1H), 4.03 (q, J = 7 Hz, 2H), 3.91 (q, J = 7 Hz, 2H),3.85 (q, J = 7 Hz, 2H), 3.82−3.68 (m, 20H), 3.63 (q, J = 7 Hz, 2H), 1.43−1.35(m, 9H), 1.22 (t, J = 7 Hz, 3H), 1.18 (t, J = 7 Hz, 6H), 1.13 (t, J = 7 Hz,3H), 1.09 (t, J = 7 Hz, 3H), 1.03 (t, J = 7 Hz, 3H).

[0110] 3. Synthesis of compound 3

[0111]

[0112] Compound 3 (65%, 1.54 g) was obtained by purifying with CH2Cl2 / methanol (200:1, v / v) column chromatography.

[0113] The structure of the synthesized compound 3 was characterized, and an appropriate amount of the final product was weighed into a nuclear magnetic tube, dissolved with deuterated chloroform, and tested at 25°C using a nuclear magnetic resonance instrument. Figure 3 The nuclear magnetic resonance spectrum of compound 3 is shown in Figure 1. Figure 3 It can be seen that the chemical shifts, integrals, and coupling splitting of each hydrogen are consistent with the target molecule, indicating that the target product is obtained, and the spectrum has no impurity peak, proving that the product reaches a high purity.

[0114] The nuclear magnetic resonance spectrum of compound 3 is shown in Figure 1. 1 H NMR (CDCl3, 600 MHz, 298 K) δ (ppm): 7.34(d, J = 1 Hz 2H), 4.37 (q, J = 7 Hz, 4H), 4.01 (t, J = 6 Hz, 4H), 2.37 (td, J= 7, 1 Hz, 4H), 1.82 (q, J = 7 Hz, 4H), 1.70 (p, J = 7 Hz, 4H), 1.54 (d, J =9 Hz, 8H), 1.39 (td, J = 7, 1 Hz, 6H).

[0115] 4. Synthesis of compound 4

[0116]

[0117] Compound 3 (1.00 g, 2.12 mmol) and KOH (357 mg, 6.36 mmol) were added to EtOH (70 mL) and then refluxed at 60°C overnight. After the reaction was completed, the solvent was removed. Then 100 mL of deionized water was added to dissolve the residue, and adjusted to pH = 4 with 1.00 M HC1 solution. The mixture was stirred for 30 minutes and filtered to obtain compound 4 (843 mg, 96%).

[0118] The structure of the synthesized compound 4 was characterized, and an appropriate amount of the final product was weighed into a nuclear magnetic tube, dissolved with deuterated dimethyl sulfoxide, and tested at 25°C using a nuclear magnetic resonance instrument. Figure 4The NMR spectrum of compound 4 is shown below. Figure 4 It can be seen that the chemical shifts, integrals, and coupling splitting of each hydrogen are consistent with the target molecule, indicating that the target product has been obtained. Furthermore, the absence of impurity peaks in the spectrum proves that the product has achieved high purity.

[0119] The 1H NMR spectrum data of compound 4 are as follows: 1 H NMR (DMSO-d6, 600 MHz, 298 K) δ (ppm):12.94 (s, 2H), 7.26 (s, 2H), 3.97 (t, J = 6 Hz, 5H), 2.47 (d, J = 7 Hz, 4H),1.70−1.66 (m, 4H), 1.58−1.54 (m, 4H), 1.41 (dq, J = 13, 7, 6 Hz, 8H).

[0120] 5. Synthesis of Compound 5

[0121]

[0122] Compound 4 (2.00 g, 4.8 mmol), tetraethylene glycol triacetonitrile (2.80 g, 14.4 mmol), and 4-dimethylaminopyridine (DMAP) (1.80 g, 9.6 mmol) were dissolved in 24 mL of anhydrous DCM. The mixture was deoxygenated under nitrogen atmosphere for 15 min, placed in an ice-water bath for 15 min, and then N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDCl) (1.84 g, 9.6 mmol) was added. The reaction proceeded for 12 h. After the reaction was complete, 30 mL of deionized water was added. The mixture was then reacted at room temperature for another 12 h. At the end of the reaction, 30 mL of deionized water was added. After three extractions with DCM, the organic phase was dried over anhydrous Na₂SO₄, dried by rotary evaporation, and purified by column chromatography using petroleum ether / acetone (2:1, v / v) as the eluent to give compound 5 (1.3 g, 35%) as a colorless oily liquid.

[0123] The structure of the synthesized compound 5 was characterized by weighing an appropriate amount of the final product into an NMR tube, dissolving it in deuterated chloroform, and testing it using an NMR spectrometer at 25°C. Figure 5 The NMR spectrum of compound 5 is shown below. Figure 5 It can be seen that the chemical shifts, integrals, and coupling splitting of each hydrogen are consistent with the target molecule, indicating that the target product has been obtained. Furthermore, the absence of impurity peaks in the spectrum proves that the product has achieved high purity.

[0124] The 1H NMR spectrum data of compound 5 are as follows: 1H NMR (CDC13, 400 MHz, 298K) δ (ppm): 7.34(s, 2H), 4.45 (t, J = 5 Hz, 4H), 3.99 (t, J = 6 Hz, 4H), 3.80 (t, J = 55 Hz,4H), 3.69−3.62 (m, 20H), 3.56 (dd, J = 5, 4 Hz, 4H), 2.35 (t, J = 7 Hz, 4H),1.80 (t, J = 7 Hz, 4H), 1.69 (d, J = 8 Hz, 4H), 1.52 (h, J = 5, 4 Hz, 8H)。

[0125] 6. Synthesis of compound 6

[0126]

[0127] Compound 5 (500 mg, 0.65 mmol), KOH (109 mg, 1.95 mmol) and 2 mL deionized water were added to 8 mL THF, stirred in an ice water bath for 5 min, then TsCl (496 mg, 2.6 mmol) was added. Stirring at 0 °C for 6 h, after centrifugal drying to remove the solvent, 20 mL DCM / H2O (v / v, 1:1) was added. In addition, the organic phase was extracted with DCM 3 times, and purified by silica gel column chromatography with petroleum ether / ethyl acetate (v / v, 1:3) as eluent, to obtain compound 6 (273 mg, 39%) as a light yellow oil.

[0128] The structure of the synthesized compound 6 was characterized, and an appropriate amount of the final product was weighed in a nuclear magnetic tube, dissolved with deuterated chloroform, and tested at 25 °C using a nuclear magnetic resonance instrument. Figure 6 The nuclear magnetic resonance spectrum of compound 6 is shown in Figure 6 It can be seen that the chemical shift, integration and coupling splitting of each hydrogen are consistent with the target molecule, indicating that the target product is obtained, and the spectrum has no impurity peak, proving that the product reaches a high purity.

[0129] The nuclear magnetic hydrogen spectrum data of compound 6 are as follows: 1H NMR (CDC13, 600 MHz, 298 K) δ (ppm): 7.78 (d, J = 8 Hz, 4H), 7.34 (s, 4H), 7.33 (s, 2H), 4.45 (t, J = 5 Hz, 4H), 4.15-4.12 (m, 4H), 3.99 (t, J = 6 Hz, 4H), 3.80 (t, J = 5 Hz, 4H), 3.67 (td, J = 5, 2 Hz, 8H), 3.63 (dt, J = 6, 3 Hz, 4H), 3.57 (p, J = 2 2 Hz, 8H), 2.43 (s, 6H), 2.36 (t, J = 7 Hz, 4H), 1.81 (td, J = 10, 8, 5 Hz, 4H), 1.69 (dd, J = 9, 5 Hz, 4H), 1.54-1.50 (m, 8H).

[0130] 7. Synthesis of compound H2G2-1

[0131]

[0132] Compound 2 (518 mg, 0.6 mmol) and Cs2CO3(196 mg, 0.6 mmol) were dissolved in 7 mL DMF. After adding compound 6 (215 mg, 0.2 mmol) dropwise, the reaction mixture was stirred at 0 °C for 20 min. The mixture was refluxed at 90 °C for 2 days. After the reaction was completed, it was filtered, spun dry, and purified by silica gel column chromatography with petroleum ether / ethyl acetate (1:2, v / v) as the eluent to obtain H2G2-1 (87 mg, 18%) as a light yellow solid.

[0133] The structure of the synthesized compound H2G2-1 was characterized, and an appropriate amount of the final product was weighed into a nuclear magnetic tube, dissolved with deuterated chloroform, and tested at 25 °C using a nuclear magnetic resonance instrument. Figure 7 The nuclear magnetic resonance spectrum of compound H2G2-1 is shown in Figure 7 It can be seen that the chemical shifts, integrals, and coupling splitting of each hydrogen are consistent with the target molecule, indicating that the target product is obtained, and the spectrum has no impurity peak, proving that the product reaches a high purity.

[0134] The nuclear magnetic hydrogen spectrum data of compound H2G2-1 are as follows: 1H NMR (500 MHz, CDCl3, 298 K, 1 mmol / L) δ (ppm): 7.47 (s, 2H), 6.99−6.87 (m, 20H), 4.53 (s, 4H), 3.94 (d, J = 44Hz, 40H), 3.77 (s, 28H), 3.70 (s, 16H), 1.51−1.20 (m, 69H), −0.13−−1.93 (m,5H).

[0135] Comparative Example 1 and Examples 2-5

[0136] Synthesis of toughened epoxy resins, including the following steps:

[0137] A solution of E51 epoxy resin monomer EPM-1, curing agent polyetheramine ED600 and H2G2-1 in chloroform was prepared, and the precursor solution was placed in liquid nitrogen and vacuumed for 30 minutes under vacuum to remove air and chloroform in the mixture. The resulting liquid was carefully injected into a prepared glass mold. After ultrasonic treatment for 3 minutes to remove small air bubbles with a capillary, it was placed in a forced air oven for programmed temperature curing according to the following steps: 30℃, 2h; 60℃, 2h; 90℃, 8h. After cooling and demolding, the obtained epoxy resin was denoted as DEP-0, DEP-1, DEP-2, DEP-3, DEP-4, respectively, according to the proportion of H2G2-1.

[0138] The amounts of substances in Comparative Example 1 and each example are shown in Table 1.

[0139] Table 1

[0140]

[0141] The DEP-0, DEP-1, DEP-2, DEP-3 and DEP-4 prepared in the examples were tested for performance; DEP-0 is a pure epoxy resin, and there is no supramolecular polymer network in the polymer; DEP-1, DEP-2, DEP-3 and DEP-4 are toughened epoxy resins based on a double network structure.

[0142] The test method is as follows:

[0143] (1) Tensile stress-strain: The mechanical properties of the polymer were measured using an Instron 34SC-1 instrument in a standard stress-strain test. The toughness value was obtained by integrating the area under the corresponding stress-strain curve. The tensile rate was 50 mm / min.

[0144] (2) Cyclic tensile test: The mechanical properties of the polymer were measured using an Instron 34SC-1 instrument in a standard stress-strain test. The toughness value was obtained by integrating the area under the corresponding stress-strain curve. The tensile rate was 50 mm / min.

[0145] (3) TGA: Thermogravimetric analysis-differential scanning calorimetry (TG-DSC) was performed using a TA Instruments (USA) SDT Q600 V8.2 Build 100 instrument with a heating rate of 10 °C / min and a constant air flow rate of 100 mL / min.

[0146] Figure 8 The tensile stress-strain curves for DEP-0, DEP-1, DEP-2, DEP-3, and DEP-4 are shown. Figure 8 As shown, the epoxy resin using the H2G2-1 monomer described in this invention exhibits significantly improved tensile strength and toughness. Among them, DEP-3 shows the best performance. Specifically, the epoxy resin toughened with the dual-network structure provided by this invention, with an H2G2-1 addition of 7 wt%, exhibits a tensile strength of 3.80 MPa, an elongation at break of 270.2%, and a toughness of 0.333 MJ / m. 3 The polyurethane without the introduction of dual non-covalent interactions exhibits a tensile strength of only 2.70 MPa, an elongation at break of only 138.0%, and a toughness of only 0.216 MJ / m. 3 .

[0147] Figure 9 The cyclic tensile test curves for DEP-0 and DEP-3 are shown. Figure 9 As shown, the hysteresis loop area of ​​DEP-3 is larger than that of DEP-0, indicating that the dual-network structure based on supramolecular polymer network endows epoxy resin with good energy dissipation capability. Figure 10 This is the TGA curve for DEP-3. (Example) Figure 10 As shown, DEP-1 to DEP-4 all begin to decompose only at temperatures above 320℃, indicating that this toughened epoxy resin based on a dual network has good thermal stability.

[0148] The applicant declares that this invention illustrates the monomers for constructing supramolecular polymer networks, the toughened epoxy resins containing them, their preparation methods, and applications through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A monomer for constructing supramolecular polymer networks, characterized in that, The monomer has the following structure: 。 2. The method for preparing monomers for constructing supramolecular polymer networks according to claim 1, wherein the preparation method comprises the following steps: (1) 1,4-diethoxybenzene, paraformaldehyde, and boron trifluoride diethyl ether react to give compound 1, and the reaction formula is as follows: ； (2) Compound 1 reacts with boron tribromide to remove the ethyl group, yielding compound 2, as shown in the following reaction formula: ； (3) Diethyl 2,5-dihydroxyterephthalate reacts with a haloheptanenitrile compound to give compound 3, as shown in the following reaction formula: ； Where X is a halogen; (4) Compound 3 undergoes a hydrolysis reaction to give compound 4, and the reaction formula is as follows: ； (5) Compound 4 reacts with tetraethylene glycol triethylene glycol to give compound 5, as shown in the following reaction formula: ； (6) Compound 5 reacts with 4-toluenesulfonyl chloride to give compound 6, as shown in the following reaction formula: ； (7) Compound 2 reacts with Compound 6 to obtain the monomer used to construct the supramolecular polymer network, as shown in the following reaction formula: 。 3. The preparation method according to claim 2, characterized in that, The molar ratio of 1,4-diethoxybenzene to paraformaldehyde in step (1) is 1:(3.0-3.5). The molar ratio of boron trifluoride ether to 1,4-diethoxybenzene in step (1) is 1:1; The reaction in step (1) is carried out at room temperature for 30 minutes; The reaction in step (1) is carried out in a solvent selected from dichloromethane and / or trichloromethane; In step (2), the molar ratio of compound 1 to boron tribromide is (1-1.5):1; In step (2), boron tribromide is added dropwise to the reaction system containing compound 1 under ice bath conditions; The reaction in step (2) is carried out at a temperature of 0°C for 6 hours. The reaction in step (2) is carried out in a solvent selected from dichloromethane and / or trichloromethane.

4. The preparation method according to claim 2, characterized in that, In step (3), the molar ratio of diethyl 2,5-dihydroxyterephthalate to the haloheptanenitrile compound is 1:(3.0-4.0). The reaction in step (3) is carried out in the presence of an alkaline substance selected from potassium carbonate and / or sodium carbonate; The molar ratio of the alkaline substance to diethyl 2,5-dihydroxyterephthalate is (3.0-4.0):1; The reaction in step (3) is carried out under reflux for 12 hours; The reaction in step (3) is carried out in an organic solvent selected from N,N-dimethylformamide; The hydrolysis reaction described in step (4) is carried out in an ethanol solution of sodium hydroxide, with the molar ratio of compound 3 to sodium hydroxide being 1:(3.0-3.5). The hydrolysis reaction in step (4) is carried out under reflux and the hydrolysis reaction time is 12 hours; After the reaction in step (4) is completed, the pH of the system is adjusted to be acidic.

5. The preparation method according to claim 2, characterized in that, In step (5), the molar ratio of compound 4 to tetraethylene glycol is 1:(3.0-3.5). The reaction in step (5) is carried out in the presence of an alkaline substance, namely 4-dimethylaminopyridine; The molar ratio of 4-dimethylaminopyridine to compound 4 is (2.0-2.1):1; The reaction described in step (5) was carried out in the presence of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride catalyst; The molar ratio of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride to compound 4 is (2.0-2.1):1; The reaction described in step (5) is carried out under nitrogen protection; The reaction temperature in step (5) is 25°C, and the reaction time is 12 hours. The reaction in step (5) is carried out in a solvent selected from dichloromethane and / or trichloromethane; In step (6), the molar ratio of compound 5 to 4-toluenesulfonyl chloride is 1:(4-4.1). The reaction in step (6) is carried out in the presence of an alkaline substance selected from potassium hydroxide and / or sodium hydroxide; The molar ratio of the alkaline substance to compound 5 is (3.0-3.2):1; The reaction in step (6) is carried out in a solvent, which is a mixture of water and tetrahydrofuran, wherein the volume ratio of water to tetrahydrofuran is 1:4.0; The reaction in step (6) is carried out at a temperature of 0°C for 6 hours.

6. The preparation method according to claim 2, characterized in that, In step (7), the molar ratio of compound 2 to compound 5 is (3.0-3.2):1; The reaction in step (7) is carried out in the presence of an alkaline substance selected from cesium carbonate; The molar ratio of the alkaline substance to compound 5 is (3.0-3.2):1; In step (7), compound 6 is added dropwise to the reaction system containing compound 2 at 0°C; The reaction in step (7) is carried out under reflux for 2-3 days; The reaction is carried out in the solvent described in step (7), which is selected from N,N-dimethylformamide.

7. A toughened epoxy resin, characterized in that, The raw materials for preparing the toughened epoxy resin include epoxy resin, curing agent, and the monomers for constructing supramolecular polymer networks as described in claim 1.

8. The toughened epoxy resin according to claim 7, characterized in that, The curing agent is selected from polyetheramine curing agents; The weight ratio of the epoxy resin to the curing agent is 1.25:1; Based on the total weight of the toughened epoxy resin as 100%, the content of the monomers used to construct the supramolecular polymer network is 1%-10%.

9. The method for preparing the toughened epoxy resin according to claim 7 or 8, characterized in that, The preparation method includes the following steps: The epoxy resin, curing agent, and monomers used to construct the supramolecular polymer network are placed in a solvent to obtain a precursor solution, which is then cured to obtain the toughened epoxy resin. The solvent is selected from chloroform and / or dichloroform; The precursor solution is freeze-dried before solidification, and then the resulting liquid is ultrasonically treated and then solidified. The curing temperature is controlled at 30°C for 2 hours; then the temperature is increased to 60°C and held for 2 hours; then the temperature is increased to 90°C and held for 8 hours.

10. The application of the toughened epoxy resin according to claim 7 or 8 in the synthesis of functional polymer materials.

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