Crosslinked polyamide material capable of being recycled in closed-loop manner as well as preparation method and application of crosslinked polyamide material

Abstract

The invention relates to a cross-linked polyamide material which can be recycled in a closed-loop manner and is shown in a formula I'as well as a preparation method and application of the cross-linked polyamide material. The polyamide material shown in the formula I'can be depolymerized after a heating reaction for a period of time under an acidic condition, and a monomeric compound can be almost completely recovered for regeneration preparation of a cross-linked polymer network without mechanical property loss, so that cyclic renewable utilization of the polyamide material is realized.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer materials technology, specifically relating to a closed-loop recyclable cross-linked polyamide material, its preparation method, and its application. Background Technology

[0002] Polyamides are a class of high-performance polymers containing amide groups in their molecular backbone, commonly known as nylon. As the leading engineering plastic, polyamides possess excellent properties and are widely used in electronics, automobiles, aerospace, and many other fields.

[0003] Cross-linked polymer materials possess excellent mechanical properties, structural stability, and solvent resistance due to their covalent network structure. However, this permanent cross-linked network structure is difficult to break even at high temperatures, making most cross-linked polymer materials difficult to recycle after use. Therefore, developing a closed-loop recyclable polyamide material that is easy to recycle and possesses certain mechanical properties, structural stability, and solvent resistance is of great significance. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention first provides a crosslinked polymer as shown in formula I'.

[0005]

[0006] Where m is 0, 1, 2, 3, 4, 5 or 6;

[0007] X is selected from -C 6-20 Aryl-OC 6-20 Aryl-, C 1-12 Alkylene -C 6-20 Aryl-SC 6-20 Aryl- or -C 6-20 Aryl-C 1-12 Alkylene-C 6-20 Aryl-, where s is a number from 1 to 25.

[0008] According to an embodiment of the present invention, m is 0, 1, 2 or 3;

[0009] X is selected from -C 6-14 Aryl-OC 6-14 Aryl-, C 1-6 Alkylene -C 6-14 Aryl-SC 6-14 Aryl- or -C 6-14 Aryl-C 1-6 Alkylene-C 6-14 Aryl-, s is a number between 2 and 15.

[0010] As an example, the crosslinked polymers are polymers I, II, III, and IV as shown below:

[0011]

[0012] In Equation IV, n = 11.0.

[0013] The present invention also provides a monomeric compound represented by the following formula Q:

[0014]

[0015] Where X has the same definition as in Equation I' above.

[0016] According to an embodiment of the present invention, X is selected from -C 6-14 Aryl-OC 6-14 Aryl-, C 1-6 Alkylene -C 6-14 Aryl-SC 6-14 Aryl- or -C 6-14 Aryl-C 1-6 Alkylene-C 6-14 Aryl-, s is a number from 2 to 15.

[0017] As an example, the monomeric compound represented by formula Q is selected from the following monomeric compound AD:

[0018]

[0019] In compound D, n = 11.0.

[0020] The present invention also provides a method for preparing the monomeric compound represented by formula Q, comprising the following steps:

[0021] Compound Q1 reacts with compound Q2 to give compound Q3; compound Q3 undergoes an internal cyclization reaction to give the monomeric compound represented by formula Q.

[0022]

[0023] Where X has the same definition as in Equation I' above; L is a halogen (e.g., chlorine).

[0024] The present invention also provides the use of the monomer compound shown in formula Q in the preparation of the crosslinked polymer shown in formula I'.

[0025] The present invention also provides a method for preparing the crosslinked polymer shown in Formula I', comprising the following steps:

[0026] The monomeric compound shown in Q is polymerized with compound T.

[0027]

[0028] Where m has the same definition as in equation I' above.

[0029] According to an embodiment of the present invention, the molar ratio of the monomer compound represented by formula Q to compound T is 1.5:1.

[0030] According to an embodiment of the present invention, the method further includes a step of curing the product after the reaction is completed.

[0031] According to an embodiment of the present invention, the reaction is carried out in N,N-dimethylformamide.

[0032] According to an embodiment of the present invention, the reaction does not require the addition of a catalyst.

[0033] According to an embodiment of the present invention, the concentration of the monomeric compound represented by formula Q is 0.1-5.0 M, for example 0.1-1.0 M, such as 0.5 M.

[0034] According to an embodiment of the present invention, the reaction is carried out at room temperature, for example, at 0-25°C.

[0035] According to an embodiment of the present invention, the reaction time is 1-36 hours, for example 12-24 hours.

[0036] According to an embodiment of the present invention, the reaction solvent is removed using a vacuum drying oven after the reaction is completed.

[0037] The present invention also provides uses of the crosslinked polymer shown in Formula I', for example, for the preparation of rigid plastics, elastomers and fibrous materials.

[0038] Specifically, it can be used as a polymer raw material for manufacturing gears, bearings, seals, gaskets, air pipes, printed films, etc., which require certain mechanical strength, dimensional stability, and weather resistance.

[0039] The present invention also provides a method for closed-loop chemical recovery of the crosslinked polymer shown in Formula I', comprising the following steps:

[0040] The cross-linked polymer shown in Formula I' was immersed in an acidic solution to undergo a degradation reaction, yielding the monomer compound shown in Formula Q and compound T.

[0041] According to an embodiment of the present invention, the degradation reaction is carried out in a haloalkane solvent or an aromatic solvent, such as in chloroform, toluene, anisole, or xylene.

[0042] According to an embodiment of the present invention, the acidic solution used in the degradation reaction is a solution of trichloroacetic acid.

[0043] According to an embodiment of the present invention, the concentration of trichloroacetic acid is 1.0-10.0M, for example 2.0-8.0M, such as 3.0M.

[0044] According to an embodiment of the present invention, the degradation reaction is carried out at 60-110°C, for example, 100°C.

[0045] According to an embodiment of the present invention, the degradation reaction time is 0.5-12.0 h, for example 1.0-3.0 h.

[0046] According to an embodiment of the present invention, after the degradation reaction is completed, the monomeric compound is separated and purified by operations such as extraction and precipitation.

[0047] The present invention also provides a method for preparing the crosslinked polymer of formula I' by recycling, comprising the following steps: reacting the monomer compound of formula Q obtained by the closed-loop chemical recycling method as described above with compound T by polymerization.

[0048] According to an embodiment of the present invention, during the recycling process, the conditions under which the monomer compound represented by formula Q undergoes polymerization with compound T are the same as the reaction conditions for preparing the crosslinked polymer represented by formula I'.

[0049] Beneficial effects of the present invention

[0050] The monomer compound represented by formula Q provided by this invention can prepare cross-linked polyamide materials at room temperature without a catalyst, and the resulting polymers range from rigid plastics to elastomers. The resulting polyamide materials can undergo depolymerization after being heated under acidic conditions for a period of time, allowing for almost complete recovery of the monomer compound for regeneration to prepare cross-linked polymer networks without loss of mechanical properties, thus achieving the recyclable and reusable use of polyamide materials.

[0051] Terminology Definitions and Explanations

[0052] The asterisks or slashes in certain groups or structures in this application The location indicates the connection point.

[0053] The term "halogen" refers to fluorine, chlorine, bromine, or iodine.

[0054] In this application, "numbers from 1 to 25" includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25.

[0055] Term "C" 1-12 "Alkylene" should be understood to refer to a straight-chain or branched saturated divalent hydrocarbon group having 1 to 12 carbon atoms. Preferably, "C" is used. 1-6 Alkylene. "C" 1-6"alkylene" refers to a straight-chain or branched divalent alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms. Examples of alkylenes include methylene, ethylene, propylene, butylene, pentylene, hexylene, isopropylene, isobutylene, sec-butylene, tert-butylene, isopentylene, 2-methylbutylene, 1-methylbutylene, 1-ethylpropylene, and 1,2-dimethylpropylene.

[0056] Term "C" 6-20 "Aryl" should be understood as representing a monocyclic, bicyclic, or tricyclic hydrocarbon ring with 6 to 20 carbon atoms that is monovalent and partially aromatic, preferably "C". 6-14 "Aromatic". The term "C" 6-14 "Aryl" should be understood to preferably represent a monovalent aromatic or partially aromatic monocyclic, bicyclic, or tricyclic hydrocarbon ring ("C") having 6, 7, 8, 9, 10, 11, 12, 13, or 14 carbon atoms. 6-14 Aryl), particularly a ring with 6 carbon atoms (“C6 aryl”), such as phenyl; or biphenyl, or a ring with 9 carbon atoms (“C9 aryl”), such as indenyl or indenyl, or a ring with 10 carbon atoms (“C9 aryl”). 10 Aryl groups, such as tetrahydronaphthyl, dihydronaphthyl, or naphthyl, or rings with 13 carbon atoms (“C”). 13 Aryl groups, such as fluorene groups, or rings with 14 carbon atoms (“C”). 14 Aryl), for example, anthracene. When the C 6-20 When the aryl group is substituted, it can be monosubstituted or polysubstituted. Furthermore, there are no restrictions on the substitution site; for example, it can be ortho, para, or meta substituted. Attached Figure Description

[0057] Figure 1 The NMR spectrum of monomer A prepared in Example 1 (the deuterated reagent used was deuterated dimethyl sulfoxide);

[0058] Figure 2 The NMR spectrum of monomer B prepared in Example 1 (the deuterated reagent used was deuterated dimethyl sulfoxide);

[0059] Figure 3 The NMR spectrum of monomer C prepared in Example 1 (the deuterated reagent used was deuterated dimethyl sulfoxide);

[0060] Figure 4 The NMR spectrum of monomer D prepared in Example 1 (the deuterated reagent used was deuterated dimethyl sulfoxide);

[0061] Figure 5 The infrared spectrum of the cross-linked polymer network I prepared in Example 2;

[0062] Figure 6 The infrared spectrum of the cross-linked polymer network II prepared in Example 2;

[0063] Figure 7 The infrared spectrum of the cross-linked polymer network III prepared in Example 2;

[0064] Figure 8 The infrared spectrum of the cross-linked polymer network IV prepared in Example 2;

[0065] Figure 9 The following are DSC diagrams of the cross-linked polymer networks I, II, III, and IV prepared in Example 2 (A: Polymer I; B: Polymer ⅠⅠ; C: Polymer ⅠⅠⅠ; D: Polymer ⅠV).

[0066] Figure 10 TGA diagrams of cross-linked polymer networks I, II, III, and IV prepared in Example 2 (A: Polymer I; B: Polymer ⅠⅠ; C: Polymer ⅠⅠⅠ; D: Polymer ⅠV);

[0067] Figure 11 The DMA diagrams of the cross-linked polymer networks I, II, III, and IV prepared in Example 2 are shown below (A: Polymer I; B: Polymer ⅠⅠ; C: Polymer ⅠⅠⅠ; D: Polymer ⅠV).

[0068] Figure 12 The stress-strain curves of cross-linked polymer networks I, II, III, and IV prepared in Example 2 are shown below (A: Polymer I; B: Polymer ⅠⅠ; C: Polymer ⅠⅠⅠ; D: Polymer ⅠV).

[0069] Figure 13 The NMR spectrum of tris(2-aminoethyl)amine prepared in Example 3 (the deuterated reagent used was deuterated chloroform);

[0070] Figure 14 The NMR spectrum of monomer A prepared in Example 3 (the deuterated reagent used was deuterated dimethyl sulfoxide);

[0071] Figure 15 The NMR spectrum of monomer B prepared in Example 3 (the deuterated reagent used was deuterated dimethyl sulfoxide);

[0072] Figure 16 The NMR spectrum of monomer C prepared in Example 3 (the deuterated reagent used was deuterated dimethyl sulfoxide);

[0073] Figure 17 The NMR spectrum of monomer D prepared in Example 3 (the deuterated reagent used was deuterated dimethyl sulfoxide);

[0074] Figure 18The infrared spectrum of the cross-linked polymer network I prepared in Example 4;

[0075] Figure 19 The image shows a DSC diagram of the cross-linked polymer network I prepared in Example 4.

[0076] Figure 20 The image shown is a TGA diagram of the cross-linked polymer network I prepared in Example 4;

[0077] Figure 21 This is a DMA diagram of the cross-linked polymer network I prepared in Example 4;

[0078] Figure 22 The stress-strain curve of the cross-linked polymer network I prepared in Example 4 is shown.

[0079] Figure 23 This is a graph showing the change in reaction conversion rate of the model compound over time in Example 5;

[0080] Figure 24 The NMR spectrum of the model compound in Example 5 (the deuterated reagent used was deuterated dimethyl sulfoxide). Detailed Implementation

[0081] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0082] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0083] The models of the nuclear magnetic resonance spectrometer, infrared spectrometer, differential scanning calorimeter, thermogravimetric analyzer, dynamic mechanical thermal analyzer, and universal tensile testing machine used in the test methods in the following embodiments are as follows:

[0084] The liquid nuclear magnetic resonance spectrometer is a Bruker Avance 400.

[0085] The infrared spectrometer is a Bruker Tensor27 FT-IR.

[0086] The differential scanning calorimeter was a DSC Q2000, and the characterization conditions were: under a nitrogen atmosphere, the heating rate was 10℃ / min.

[0087] The thermogravimetric analyzer was a PerkinElmer Pyris 1TGA, and the characterization conditions were: under a nitrogen atmosphere, a heating rate of 10 °C / min, from 30 °C to 700 °C.

[0088] The dynamic mechanical thermal analyzer model is DMA Q800. The characterization conditions are: test at a frequency of 1 Hz and a strain of 0.1%, with a heating rate of 3 ℃ / min from -80 ℃ to 250 ℃.

[0089] The universal tensile testing machine is model Instron 3365. The characterization conditions are: tensile test, strain rate of 10 mm / min, temperature of approximately 25℃, and equipped with a 1000N sensor.

[0090] Example 1

[0091] 1.1 The preparation route of polymer monomer A is as follows, and the specific steps are as follows:

[0092]

[0093] 1) Dissolve 10.00 g of 3,4-dihydrocoumarin in acetic anhydride (60 mL). Add dropwise a mixture of fuming nitric acid (5.53 g) and glacial acetic acid (7 mL) at 18-20 °C. React the mixture at room temperature for 1 hour, then pour it into an ice-water mixture (300 mL). Collect the precipitate and wash thoroughly with water. Recrystallize several times in a mixture of petroleum ether and ethyl acetate to give compound 1a (9.26 g, 71% yield).

[0094] 2) Compound 1a (9.26 g) was dissolved in dichloromethane (100 mL), and propylamine (5.66 g) was added dropwise. After stirring at room temperature for 1 h, the precipitate was collected, washed thoroughly with DCM, and dried under vacuum to obtain compound 1b (11.97 g, yield 99%).

[0095] 3) Add palladium / carbon (0.5 g) to a methanol (40 mL) solution of compound 1b (5.0 g) and stir overnight under a hydrogen (balloon) atmosphere. Then filter the mixture through diatomaceous earth, using ethyl acetate as the washing solution. Evaporate the solvent and perform column chromatography (V... 二氯甲烷 V 甲醇 Purification was performed using a ratio of 20:1 to obtain compound 1c (4.82 g, 95% yield).

[0096] 4) Compound 1c (4.00 g) and triethylamine (1.82 g) were dissolved in tetrahydrofuran (90 mL). After stirring and dissolving, 4,4'-oxobis(benzoyl chloride) (2.42 g) was slowly added at 0 °C. After reacting at room temperature for 1 hour, the solvent was removed by filtration. The resulting crude solid was washed several times with deionized water and dried to obtain compound 1d (5.37 g, yield 98%).

[0097] 5) Compound 1d (5.37 g) was added to a solution of trichloroacetic acid (26.28 g) in toluene (40 mL). The reaction was carried out at 100 °C for 1 hour. The mixture was concentrated under reduced pressure and redissolved in dichloromethane (80 mL). The mixture was washed once with deionized water (100 mL), and then a saturated sodium bicarbonate solution (100 mL) was added to the mixture. The solid gradually precipitated, and the solvent was removed by filtration. The resulting crude solid product was washed several times with deionized water and dried to give polymer monomer A (4.00 g, 90% yield). The NMR spectrum is shown below. Figure 1 As shown.

[0098] 1.2 The preparation route of polymer monomer B is shown below, and the specific steps are as follows:

[0099]

[0100] 1) Compound 1c (4.00 g) and triethylamine (1.82 g) were dissolved in tetrahydrofuran (90 mL), and adipic acid chloride (1.50 g) was slowly added at 0 °C. The reaction was carried out at room temperature for 1 hour. The solvent was removed by filtration, and the resulting crude solid was washed several times with deionized water and dried to obtain compound 2a (4.47 g, yield 98%).

[0101] 2) Compound 2a (4.47 g) was added to a solution of trichloroacetic acid (26.28 g) in toluene (40 mL). The reaction was carried out at 100 °C for 1 hour. The mixture was concentrated under reduced pressure and redissolved in dichloromethane (80 mL). The residue was washed once with deionized water (100 mL), and then a saturated sodium bicarbonate solution (100 mL) was added to the mixture. The solid gradually precipitated, and the solvent was removed by filtration. The resulting crude solid product was washed several times with deionized water and dried to give polymer monomer B (3.24 g, yield 92%). Its NMR spectrum is shown below. Figure 2 As shown.

[0102] 1.3 The preparation route of polymer monomer C is shown below, and the specific steps are as follows:

[0103]

[0104] 1) At 0 °C, oxaloyl chloride (6.86 g) (2.0 M dichloromethane solution) and a catalytic amount of DMF were added to a solution of 3,6,9-trioxadecanoic acid (2.0 g) in dichloromethane (60 mL). After 5 minutes, the solution was heated to room temperature and stirred for 1 hour. The solvent was evaporated and then dissolved in dichloromethane (20.0 mL) to prepare a dichloromethane solution of diacyl chloride. The dichloromethane solution of diacyl chloride was slowly added to a solution of compound 1c (4.4 g) and triethylamine (1.99 g) in tetrahydrofuran (100 mL). The reaction was carried out at room temperature for 1 hour. The reaction mixture was concentrated and subjected to column chromatography (V) 二氯甲烷 V 甲醇 Purification was performed at a ratio of 10:1 to give compound 3a (5.32 g, 94% yield).

[0105] 2) Compound 3a (5.32 g) was added to a solution of trichloroacetic acid (27.38 g) in toluene (40 mL). The reaction was carried out at 100 °C for 1 hour. The mixture was concentrated under reduced pressure and redissolved in dichloromethane (80 mL). The residue was washed with deionized water (1 × 80 mL) and saturated sodium bicarbonate solution (2 × 80 mL). The organic layer was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give polymer monomer C (3.59 g, yield 88%). Its NMR spectrum is shown below. Figure 3 As shown.

[0106] The preparation route of polymer monomer D is shown below, and the specific steps are as follows:

[0107]

[0108] 1) At 0°C, oxaloyl chloride (5.17 g) (2.0 M dichloromethane solution) and a catalytic amount of DMF were added to a solution of polyethylene glycol bis(carboxymethyl) ether (4.06 g) (n = 11.0) in dichloromethane (45 mL). After 5 minutes, the solution was allowed to warm to room temperature and stirred for 1 hour. The solvent was removed by evaporation, and the remaining diacyl chloride was evaporated twice to remove DCM, and then dissolved in DCM (15.0 mL) to prepare a dichloromethane solution of diacyl chloride. The dichloromethane solution of diacyl chloride was slowly added to a solution of compound 1c (3.16 g) and triethylamine (1.44 g) in THF (70 mL) under stirring. The reaction was carried out at room temperature for 1 hour. After concentrating the reaction mixture, column chromatography (V) was performed. 二氯甲烷 V 甲醇 Purification was performed at a ratio of 10:1 to give compound 4a (5.30 g, 74% yield).

[0109] 2) Compound 4a (5.30 g) was added to a solution of trichloroacetic acid (16.30 g) in toluene (25 mL). The reaction was carried out at 100 °C for 1 hour. The mixture was concentrated under reduced pressure and redissolved in dichloromethane (50 mL). The residue was washed with deionized water (1 × 50 mL) and saturated sodium bicarbonate solution (2 × 50 mL). The organic layer was dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give polymer monomer D (3.95 g, yield 84%). Its NMR spectrum is shown below. Figure 4 As shown.

[0110] Example 2

[0111] 2.1 Preparation of Polymer I, the specific steps are as follows:

[0112]

[0113] Monomer A (1.50 g) was dissolved in N,N-dimethylformamide (5.5 mL) at 0 °C, and tris(2-aminoethyl)amine (0.27 g) was added. After stirring at 0 °C for 30 seconds, the reaction mixture was transferred to a mold and cured for another 24 hours. After removing the solvent under vacuum, polymer I was obtained.

[0114] 2.2 Preparation of Polymer II, the specific steps are as follows:

[0115]

[0116] Monomer B (1.50 g) was dissolved in N,N-dimethylformamide (6.9 mL) at 0 °C, and tris(2-aminoethyl)amine (0.34 g) was added. After stirring at 0 °C for 30 seconds, the reaction mixture was transferred to a mold and cured for another 24 hours. After removing the solvent under vacuum, polymer II was obtained.

[0117] 2.3 Preparation of Polymer III, the specific steps are as follows:

[0118]

[0119] Monomer C (2.30 g) was dissolved in N,N-dimethylformamide (5.0 mL) at 0 °C, and tris(2-aminoethyl)amine (0.25 g) was added. After stirring at 0 °C for 30 seconds, the reaction mixture was transferred to a mold and cured for another 24 hours. After removing the solvent under vacuum, polymer III was obtained.

[0120] 2.3 Preparation of Polymer IV, the specific steps are as follows:

[0121]

[0122] Monomer D (2.30 g) was dissolved in N,N-dimethylformamide (4.8 mL) at 0 °C, and tris(2-aminoethyl)amine (0.24 g) was added. After stirring at 0 °C for 30 seconds, the reaction mixture was transferred to a mold and cured for another 24 hours. After removing the solvent under vacuum, polymer IV was obtained.

[0123] Example 3

[0124] To simulate and verify whether the raw materials used to prepare the crosslinked polymer of this application can be recycled in a closed loop, the recyclability of tris(2-aminoethyl)amine and polymer monomer AD was tested using the following method.

[0125] 3.1 The specific steps for the chemical recovery of tris(2-aminoethyl)amine from acidic aqueous solution are as follows:

[0126] Tris(2-aminoethyl)amine (1.0 g) was added to a stirred aqueous solution of trichloroacetic acid (16.72 g) (34 mL). After the tris(2-aminoethyl)amine was completely neutralized, an alkaline ion exchange resin was used ( 900(OH) (70g) was used to remove trichloroacetic acid ions. The resulting deionized tri(2-aminoethyl)amine aqueous solution (pH>12) was filtered, and the ion exchange resin was recovered for reuse. Water was removed by distillation to obtain tri(2-aminoethyl)amine (0.94g, yield 94%).

[0127] 3.2 Closed-loop chemical recovery of polymer I, the specific steps are as follows:

[0128] Polymer I (1.0 g) was added to a solution of trichloroacetic acid (2.52 g) in toluene (8 mL). The reaction was carried out at 100 °C for 1 hour. The mixture was concentrated under reduced pressure and redissolved in DCM (30 mL). Subsequently, deionized water was added to the reaction mixture for extraction. Sodium bicarbonate was then added to the organic phase. The solid was obtained by filtration and washed several times with deionized water to give monomer A (0.77 g, 90% yield).

[0129] 3.3 Closed-loop chemical recovery of polymer B, the specific steps are as follows:

[0130] Polymer II (1.0 g) was added to a solution of trichloroacetic acid (2.62 g) in toluene (8 mL). The reaction was carried out at 100 °C for 1 hour. The mixture was concentrated under reduced pressure and redissolved in DCM (30 mL). Subsequently, deionized water was added to the reaction mixture for extraction. Sodium bicarbonate was then added to the organic phase. The solid was obtained by filtration and washed several times with deionized water to give monomer B (0.75 g, 91% yield).

[0131] 3.4 Closed-loop chemical recovery of polymer C, the specific steps are as follows:

[0132] Polymer III (1.0 g) was added to a solution of trichloroacetic acid (2.67 g) in toluene (8 mL). The reaction was carried out at 100 °C for 1 h. The mixture was concentrated under reduced pressure and redissolved in DCM (30 mL). Subsequently, deionized water was added to the reaction mixture for extraction. Sodium bicarbonate was then added to the organic phase, and the solid was removed by filtration. The organic layer was washed with deionized water, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give monomer C (0.76 g, 90% yield).

[0133] 3.5 Closed-loop chemical recovery of polymer D, the specific steps are as follows:

[0134] Polymer IV (0.8 g) was added to a solution of trichloroacetic acid (2.47 g) in toluene (8 mL). The reaction was carried out at 100 °C for 1 h. The mixture was concentrated under reduced pressure and redissolved in DCM (30 mL). Subsequently, deionized water was added to the reaction mixture for extraction. Sodium bicarbonate was then added to the organic phase, and the solid was removed by filtration. The organic layer was washed with deionized water, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure to give monomer C (0.67 g, 92% yield).

[0135] Example 4

[0136] The specific steps for preparing recycled polymer I are as follows:

[0137] Monomer A (1.50 g) obtained from the closed-loop chemical recovery in Example 3 was dissolved in N,N-dimethylformamide (5.5 mL) at 0 °C, and tris(2-aminoethyl)amine (0.27 g) recovered in Example 3 was added. After stirring at 0 °C for 30 seconds, the reaction mixture was transferred to a mold and cured for another 24 hours. After removing the solvent under vacuum, polymer I was obtained.

[0138] Its infrared spectrum is as follows Figure 18 As shown, the DSC diagram is as follows Figure 19 As shown, the TGA diagram is as follows: Figure 20 As shown, DMA is as follows Figure 21 As shown, the stress-strain curve is as follows: Figure 22 As shown, comparing the test data of FTIR, DSC, TGA, DMA and tensile tests of recycled polymer I with those of unrecycled polymer I, it can be seen that the monomer compounds after degradation and recycling of crosslinked polyamide can be used to regenerate crosslinked polyamide networks without loss of mechanical properties, thereby realizing the recycling of crosslinked polyamide.

[0139] Example 5

[0140] Model compound M was mixed with n-hexylamine at a concentration of 0.2 M in deuterated dimethyl sulfoxide and reacted at room temperature. The conversion rate of model compound M was monitored using nuclear magnetic resonance spectroscopy. The monitoring results are as follows: Figure 23 As shown, by Figure 23 It can be seen that the final conversion rate of model compound M can reach over 99%. The reaction results of model compound M with n-hexylamine prove that the monomer compound Q and compound T shown in formula Q can be almost 100% converted into the crosslinked polymer shown in formula I' during the polymer preparation process of this application.

[0141] The preparation process of model compound M is as follows:

[0142]

[0143] The NMR structure of model compound M is as follows: Figure 24 As shown.

[0144] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The cross-linked polymer shown in Formula I', in, m can be 0, 1, 2, 3, 4, 5, or 6; X is selected from -C 6-20 Aryl-OC 6-20 Aryl-, C 1-12 Alkylene -C 6-20 Aryl-SC 6-20 Aryl- or -C 6-20 Aryl-C 1-12 Alkylene-C 6-20 Aryl-, where s is a number from 1 to 25.

2. The crosslinked polymer according to claim 1, wherein, m can be 0, 1, 2, or 3; X is selected from -C 6-14 Aryl-OC 6-14 Aryl-, C 1-6 Alkylene -C 6-14 Aryl-SC 6-14 Aryl- or -C 6-14 Aryl-C 1-6 Alkylene-C 6-14 Aryl-, s is a number from 2 to 15.

3. The crosslinked polymer according to claim 1 or 2, wherein, The crosslinked polymers are polymers I, II, III, and IV as shown below: In Equation IV, n = 11.

0.

4. The monomeric compound represented by formula Q: in, X is selected from -C 6-20 Aryl-OC 6-20 Aryl-, C 1-12 Alkylene -C 6-20 Aryl-SC 6-20 Aryl- or -C 6-20 Aryl-C 1-12 Alkylene-C 6-20 aryl-; s is a number from 2 to 25 Preferably, X is selected from -C 6-14 Aryl-OC 6-14 Aryl-, C 1-6 Alkylene -C 6-14 Aryl-SC 6-14 Aryl- or -C 6-14 Aryl-C 1-6 Alkylene-C 6-14 aryl-, s is a number from 2 to 15; Preferably, the monomeric compound represented by formula Q is selected from the following monomeric compounds AD: In compound D, n = 11.

0.

5. A method for preparing the monomeric compound represented by formula Q according to claim 4, wherein, Includes the following steps: Compound Q1 reacts with compound Q2 to give compound Q3; compound Q3 undergoes a cyclization reaction to give the monomeric compound represented by formula Q. X has the definition of any one of claims 1-3; L is a halogen; 6. Use of the monomer compound of formula Q according to claim 4 in the preparation of the crosslinked polymer of I' according to any one of claims 1-3.

7. A method for preparing the crosslinked polymer of formula I' according to any one of claims 1-3, wherein, Includes the following steps: The monomeric compound represented by formula Q according to claim 4 is subjected to a polymerization reaction with compound T; Wherein, m has the definition as described in any one of claims 1-3; Preferably, the molar ratio of the monomer compound represented by formula Q to compound T is 1.5:

1.

8. Use of the crosslinked polymer of Formula I' according to any one of claims 1-3 in the preparation of rigid plastics, elastomers and fibrous materials; Preferably, it is a polymer raw material used in the preparation of gears, bearings, seals, gaskets, air pipes, and printed films where certain requirements are placed on mechanical strength, dimensional stability, and weather resistance.

9. A method for closed-loop chemical recovery of the crosslinked polymer represented by Formula I' according to any one of claims 1-3, wherein, Includes the following steps: The cross-linked polymer of Formula I' as described in any one of claims 1-3 is immersed in an acidic solution to undergo a degradation reaction, yielding the monomer compound of Formula Q and compound T.

10. A method for preparing the crosslinked polymer of formula I' through recycling, wherein, The process includes the following steps: polymerizing the monomer compound of formula Q obtained by the closed-loop chemical recovery method of claim 9 with compound T; Preferably, during the recycling process, the polymerization reaction conditions between the monomer compound represented by formula Q and compound T are the same as the reaction conditions of the method for preparing the crosslinked polymer represented by formula I' according to claim 7.

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