Polyester-based chemically recyclable crosslinked elastomer and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and discloses a polyester-based chemically recyclable crosslinked elastomer and a preparation method thereof. According to the chemically recyclable cross-linked elastomer, an aliphatic lactone monomer and a furyl substituted lactone monomer are subjected to a copolymerization reaction under the action of a catalyst to form a copolyester prepolymer, and the prepolymer further reacts with a cross-linking agent containing complementary dynamic bonds through a furyl side group of the prepolymer to form a reversible cross-linked network. The cross-linked network can simultaneously realize controllable dissociation of dynamic covalent bonds and selective degradation of a polyester main chain under thermal or chemical stimulation, so that an original monomer is efficiently recovered. The cross-linked elastomer provided by the invention has the advantages of excellent mechanical properties, good heat resistance, capability of closed-loop chemical circulation and the like.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology and relates to a polyester-based chemically cyclic crosslinkable elastomer and its preparation method. Background Technology

[0002] Polyolefin thermoplastic elastomers (TPEs) are lightweight, inexpensive, and have excellent performance. However, they are mainly composed of stable carbon-hydrogen and carbon-carbon bonds, making them extremely stable and difficult to recycle through degradation, resulting in both environmental pollution and resource waste. Therefore, developing thermoplastic elastomers with chemical recycling capabilities (polymer degradation into polymer precursors) is an urgent need in this field. Polyesters are ideal chemically recyclable materials and are a suitable alternative to polyolefin elastomers. Currently, although the preparation of ABA-type polyester-based thermoplastic elastomers via block polymerization and the achievement of chemical recycling have been reported, these elastomers produced through physical crosslinking of crystalline block copolymers exhibit poor resilience (resilience < 65%) and insufficient heat resistance (melting point < 74 ℃). Nat. Commun. 2024, 15 , 7904; Angew. Chem., Int. Ed. 2025, 64, e202415388); Good resilience (resilience ~90%) of polyester elastomers was achieved through dynamic chemical crosslinking based on acetal bonds, but the resulting elastomers exhibited extremely low mechanical strength (tensile strength <0.6 MPa). Adv. Mother. 2023, 2300954). Therefore, thermoplastic elastomers with good resilience (>80%), heat resistance (working temperature >100℃) and excellent mechanical strength (tensile strength >10MPa) remain a technological gap. Summary of the Invention

[0003] This invention addresses the problems existing in polyester-based elastomers by providing a polyester-based chemically cyclically crosslinkable elastomer and its preparation method.

[0004] The technical solution of the present invention: A polyester-based chemically cyclic crosslinkable elastomer is obtained by uniformly mixing a furan-containing polyester with a crosslinking agent and carrying out a Diels-Alder reaction. This crosslinked elastomer has... Figure 1 The linear furanyl polyester backbone 1 and the crosslinking point 2 formed by the furanyl polyester backbone and the crosslinking agent through the Diels-Alder reaction are shown.

[0005] The structural formula of the polyester containing furan groups is: in, R1 R 2 R 3 R 4 R 5 R 6 Selected from hydrogen, Alkyl groups with 1 to 20 carbon atoms, R 1 R 2 R 3 R 4 R 5 R 6 Same or different; R 1 R 2 R 3 R 4 R 5 R 6 At least one is a is 1, 2, or 3; b is 0, 1, 2, or 3; x is an integer between 0 and 10; The structural formulas for A, B, and C are: R 7 R 8 R 9 R 10 R 11 R 12 Selected from hydrogen, alkyl groups with 1 to 20 carbon atoms, R 7 R 8 R 9 R 10 R 11 R 12 Same or different; c is 1, 2 or 3; d is 0, 1, 2 or 3; A, B, and C may be the same or different; m is an integer between 1 and 10000, n is an integer between 10 and 10000; o and p are integers between 0 and 10000; The crosslinking agent is a bismaleimide compound linked by bridging groups, and its structural formula is: Among them, R 13 The crosslinking agent preferably has the following structure: It contains 1-40 carbon alkane or aromatic subunits. , , , , , , .

[0006] A method for preparing a polyester-based chemically cyclic crosslinkable elastomer includes the following steps: S1, Synthesis of furan group polyesters; Furanyl lactone monomer 1 and one or more lactone monomers 2 are dissolved in a first organic solvent with or without an initiator. The molar ratio of monomer 1 to monomer 2 is 1:0.01 to 1:1000. The mixture is stirred at room temperature for 5 minutes. Then, a catalyst is added (the molar ratio of catalyst to monomer 1 is 1:10 to 1:10000). When the conversion rates of furanyl lactone monomer 1 and lactone monomer 2 remain unchanged, water or an acidic substance is added to terminate the reaction. A second organic solvent is added to precipitate the polymer. The precipitate is filtered, washed, and dried to obtain furanyl polyester. S2, crosslinking of furanyl polyester; The furan-based polyester obtained in step S1 is dissolved in a third organic solvent, and then a crosslinking agent is added. The molar ratio of furan groups in the furan-based polyester to the crosslinking agent is 1:0.01 to 1:100. The mixture is stirred at room temperature for 0.1 to 12 hours to ensure uniform mixing. Subsequently, the solvent is removed in a mold, and the resulting solid is placed under heating conditions (40 to 100°C) for 0.1 to 24 hours to allow the furan groups and maleimide groups to undergo a Diels-Alder reaction, forming a dynamic covalent crosslinking network, and finally obtaining a polyester-based chemically cyclic crosslinkable elastomer.

[0007] The structural formula of the furanyl lactone monomer 1 is as follows: The structural formula of the lactone monomer 2 is as follows: The catalyst is a metal catalyst, an organic catalyst, or an inorganic catalyst; The metal catalyst is Ln(OR) 14 )3, Ln(CH2SiMe3)(THF)x, Ln[N(SiMe3)2], M(OR 14 )2, M(CH2SiMe3)2 or M[N(SiMe3)2]2, wherein Ln is selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Sc, Y and Lu; M is selected from Zn and Mg; R 14 Selected from alkyl groups of 1 to 20 carbon atoms, aryl groups of 6 to 24 carbon atoms, and olefins of 2 to 12 carbon atoms; Me is methyl; The organic catalyst is an organic base or an organic acid, wherein the organic acid is diphenyl phosphate, and the organic base is: Among them, R 15 R 16R 17 R is a hydrocarbon group selected from 1 to 20 (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 18, 19) carbon atoms. 15 R 16 R 17 Same or different; The inorganic catalyst is sodium alkoxide containing 1 to 40 carbon atoms or potassium alkoxide containing 1 to 40 carbon atoms; The initiator is any one of monohydric alcohols, dihydric alcohols, polyhydric alcohols, thiols, and amines containing 1 to 40 (e.g., 2, 3, 5, 6, 8, 10, 12, 15, 20, 25, 30, 32, 35, 38) carbon atoms.

[0008] When water or acidic substances are added to terminate the polymerization reaction, the amount of water or acidic substances added is 1 to 10 times the equivalent of the catalyst (e.g., 1, 3, 5, 8, 10 times).

[0009] The acidic substance is at least one of acetic acid, benzoic acid, hydrochloric acid, sulfuric acid, and phosphoric acid.

[0010] The first organic solvent is at least one of benzene, toluene, ethylbenzene, hexane, heptane, octane, tetrahydrofuran, diethyl ether, petroleum ether, chloroform, dichloromethane, and N,N-dimethylformamide.

[0011] The second organic solvent includes at least one of hexane, heptane, octane, tetrahydrofuran, diethyl ether, petroleum ether, methanol, and ethanol.

[0012] The third organic solvent includes dichloromethane, tetrahydrofuran, toluene, ethylbenzene, ethyl acetate, acetonitrile, etc. N , N At least one of dimethylformamide.

[0013] A method for depolymerizing a polyester-based chemically recyclable crosslinkable elastomer involves placing the elastomer in the presence of a Lewis acid catalyst and pyrolyzing it under reduced pressure conditions (0.01-760 mmHg) within a temperature range of 90-300 °C to efficiently and selectively recover furanyl lactone monomer 1 and lactone monomer 2.

[0014] The Lewis acid catalyst includes at least one of zinc chloride, zinc acetate, magnesium chloride, ferric chloride, ferrous chloride, stannous octoate, and zinc acetate.

[0015] The beneficial effects of this invention are: The cross-linked elastomer prepared by this method successfully combines the high strength and high resilience of chemical cross-linked networks with the reversible properties of dynamic bonds; Based on dynamic Diels-Alder crosslinking, this elastomer can be efficiently depolymerized under mild conditions of 90~300℃ in the presence of Lewis acid catalysts, recovering the original lactone monomers with high yield (>90%) and high selectivity, realizing a true chemical closed-loop cycle of "monomer → high-performance material → monomer", which is in line with the concepts of green chemistry and sustainable development. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a crosslinked elastic structure: 1-a linear furan-based polyester backbone; 2-crosslinking points formed by the linear furan polyester backbone and the crosslinking agent through a Diels-Alder reaction; Figure 2 A comparison of atomic force images of the furan-based polyester synthesized in Example 2 and the polyester crosslinked elastomer formed by reacting the furan-based polyester prepolymer synthesized in Example 4 with a crosslinking agent is shown. Among them, (a) is the atomic force image of the furan-based polyester prepolymer in Example 2, and (b) is the atomic force image of the polyester crosslinked elastomer formed by reacting the furan-based polyester prepolymer with a crosslinking agent. Figure 3 The stress-strain curves of the crosslinked elastomer P4 prepared in Example 5 are shown. Figure 4 The uniaxial tensile stress-strain curves of the crosslinked elastomer P4 prepared in Example 5 under cyclic tensile loading are shown. Figure 5 This is a comparison of the 1H NMR spectra of the degradation product of the crosslinked elastomer P2 prepared in Example 4 of the present invention with the pre-crosslinked furanyl polyester pre-P2, the monomers α-methyl-δ-valerolactone and α-furanmethyl-δ-valerolactone that form pre-P2. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0018] Example 1: Furanyl polyester poly(α-methyl- e -caprolactone- co - α -furanmethyl- e Synthesis of β-caprolactone (pre-P1) pre-P1 In a nitrogen-filled glove box, add to a 100 mL Schlenk reaction flask that has been baked and cooled at high temperature. α -methyl- e -Caprolactone (12.8 g, 100.0 mmol), α -furanmethyl- e-Caprolactone (1.94 g, 10.0 mmol), initiator 1,4-benzenedimethanol (BDM) (0.069 g, 0.5 mmol), and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) (0.139 g, 1 mmol). 30 mL of anhydrous toluene was added, and the reaction was magnetically stirred at room temperature for 24 hours.

[0019] After the reaction was complete, the reaction flask was cooled to room temperature. 5 mL of benzoic acid / CDCl3 (10 mg / mL) was added to the system to quench the polymerization reaction. Then, under vigorous stirring, the reaction solution was poured into 500 mL of ice-cold methanol, and a precipitate immediately formed. The precipitate was washed three times (50 mL each time) with ice-cold methanol to remove unreacted monomers and oligomers. The resulting precipitate was transferred to a petri dish and dried in a vacuum oven at 40 °C to constant weight to obtain the product. The weight was 12.6 g, with a yield of approximately 92%. The product was analyzed by proton nuclear magnetic resonance (NMR) spectroscopy (1H NMR). 1 ¹H NMR (CDCl₃) analysis, with furan ring characteristic peaks ( d The furan group content was calculated to be 10% based on the ratio of the methylene peak area of ​​the polycaprolactone backbone (6.2-7.4 ppm). The molecular weight was determined using gel permeation chromatography (GPC, with DCM as the mobile phase and polystyrene as the standard). The number-average molecular weight (MA) was... M n The molecular weight distribution is 25 kg / mol. , M w / M n The value is 1.54.

[0020] Example 2: Furanyl polyester poly(α-methyl- d -valerol- co - α -furanmethyl- d Synthesis of pre-P2 (-valerolactone) pre-P2 The operating steps are the same as in Example 1, except that the raw materials are replaced with: α -methyl- d -Velolactone (11.4 g, 100.0 mmol), α -furanmethyl- d -Velolactone (1.80 g, 10.0 mmol), BDM (0.069 g, 0.05 mmol), and TBD (0.139 g, 0.1 mmol). The reaction was carried out at room temperature for 20 hours. After quenching, precipitation was performed in ice-cold methanol to give 11.8 g of a white viscous liquid pre-P2 prepolymer, with a yield of approximately 90%. GPC analysis showed that...M n It is 26 kg / mol. It is 1.63.

[0021] Example 3: Crosslinked Elastomer Preparation The furanyl polyester poly(α-methyl-) prepared in Example 1 was used e -caprolactone- co - α -furanmethyl- e 2.00 g of caprolactone (containing 1.50 mmol of furan groups) and N , N -(4,4-methylenediphenyl)bismaleimide (BMI, 0.26 g, 0.75 mmol) was added to a 50 mL round-bottom flask. 15 mL of dichloromethane was added, and the mixture was magnetically stirred at room temperature for approximately 2 hours until a completely homogeneous solution was formed. The clarified solution was poured into a rectangular polytetrafluoroethylene (PTFE) mold. The mold was placed in a fume hood and allowed to stand at room temperature for 48 hours to allow the solvent to evaporate slowly and completely. Subsequently, the mold, which had formed a solid film, was transferred to a vacuum oven and heat-treated at 70 °C for 24 hours to complete the Diels-Alder crosslinking reaction between furan and maleimide.

[0022] After heat treatment, turn off the oven power and allow it to cool naturally to room temperature. Remove the mold to obtain a pale yellow, transparent, and highly elastic cross-linked elastomer film P1 with a thickness of approximately 0.8 mm. Its gel content, determined by the swelling method (toluene, 25°C), is 98.3%.

[0023] Example 4: Crosslinked Elastomer Preparation The operating steps are the same as in Example 3, except that the pre-P2 furanyl polyester (2.00 g) prepared in Example 2 is used instead of... N , N Crosslinking was performed using 0.30 g of 4,4-methylenediphenyl)bismaleimide. The resulting elastomer film P2 was a light yellow, transparent film with a gel content of 99.0%.

[0024] Example 5: Preparation of crosslinked elastomers with different ratios of lactone monomers to furan monomers This embodiment aims to illustrate that by adjusting the feeding ratio of lactone monomer and furan-containing functional monomer, the content of furan groups in the prepolymer can be effectively controlled, thereby achieving precise control over the network density and mechanical properties of the final crosslinked elastomer, demonstrating the advantages of this invention in terms of material performance designability.

[0025] (1) Synthesis of furanyl polyester: With the catalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (0.1 mmol) and initiator 1,4-benzenedimethanol (0.05 mmol) fixed, the amounts of these components were varied. α -methyl- d -Velolactone and α -furanmethyl- d A series of furan-based polyesters with different furan contents were synthesized by adjusting the molar ratio of -valerolactone. The operation steps were the same as in Example 1. The specific feed and results are as follows:

[0026] (2) Preparation of cross-linked elastomers: Take 2.00 g each of the three furanyl polyesters pre-P3, pre-P4, and pre-P5 prepared above, and prepare crosslinked elastomers according to the process in Example 3. The resulting elastomers are labeled as P3, P4, and P5 respectively.

[0027] (3) Performance characterization and comparison: The gel content, swelling degree, and mechanical properties of the three elastomers were tested, and the results are summarized below:

[0028] Example 6: Crosslinked elastomers formed from furan-based polyesters prepared using different catalytic systems This embodiment aims to illustrate the role of different catalytic systems in synthesis. α -methyl- d -valerol and α -furanmethyl- d The applicability of valproic acid in the preparation of furanyl polyesters and its effect on the final elastomer properties.

[0029] Prepolymers of the same composition were synthesized using a metal catalyst (La[N(SiMe3)2]3), an organic catalyst (1,5,7-triazabicyclo[4.4.0]dec-5-ene), and an inorganic catalyst (sodium methoxide), respectively. The specific steps are as follows: (1) Preparation of furan-based polyester pre-P6 using La[N(SiMe3)2]3 as a catalyst: The operation is the same as in Example 1. α -methyl- d -Velolactone (11.1 g, 97.0 mmol), α -furanmethyl- d-Velolactone (0.54 g, 3.0 mmol), 1,4-benzenedimethanol (0.0069 g, 0.05 mmol), and La[N(SiMe3)2]3 (0.0620 g, 0.1 mmol). The reaction was carried out at room temperature for 3 hours. After drying the precipitate, 10.7 g of white solid furanyl polyester pre-P6 was obtained, with a yield of 92%. GPC: M n = 170 kg / mol, = 1.51.

[0030] (2) Preparation of furanyl polyester pre-P7 using 1,5,7-triazabicyclo[4.4.0]dec-5-ene as a catalyst: Same as in Example 2, α -methyl- d -Velolactone (11.1 g, 97.0 mmol), α -furanmethyl- d -Velolactone (0.54 g, 3.0 mmol), 1,4-benzenedimethanol (0.0069 g, 0.05 mmol), and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (0.0139 g, 0.1 mmol). The reaction was carried out at room temperature for 20 hours. After quenching, precipitation was performed in ice-cold methanol to give 10.5 g of white viscous furanyl polyester pre-P7, with a yield of approximately 90%. GPC analysis showed that its... M n It is 161 kg / mol. It is 1.63.

[0031] (3) Preparation of furan-based polyester pre-P8 using sodium methoxide as a catalyst: α -methyl- d -Velolactone (11.1 g, 97.0 mmol), α -furanmethyl- d -Velolactone (0.54 g, 3.0 mmol), 1,4-benzenedimethanol (0.0069 g, 0.05 mmol), and sodium methoxide (0.0054 g, 0.1 mmol). The reaction was carried out at room temperature for 24 hours. Subsequent processing was the same as above, yielding 9.2 g of white solid furanyl polyester pre-P8, in 79% yield. GPC: M n =78.9 kg / mol, = 2.01.

[0032] (4) Preparation and performance comparison of cross-linked elastomers: The above three furanyl polyesters were respectively subjected to the method described in Example 3, and...N , N Elastomers P6, P7, and P8 were prepared by crosslinking with 4,4-methylenediphenyl)bismaleimide. Their properties are compared below:

[0033] Example 7: Preparation of crosslinked elastomers from furanyl polyesters formed by different lactone monomers and α-furanmethyl-δ-valerolactone. (1) Furanyl polyester poly(β-methyl- d -valerol- co - α -furanmethyl- d -Velolactone) (pre-P9) and poly( α -Ethyl- d -valerol- co - α -furanmethyl- d Synthesis of pre-P10 (-valerolactone): By fixing the furan monomer (α-furanmethyl-δ-valerolactone) at a feed concentration of 10 mol%, and changing the composition of the lactone monomer, two furan-based polyesters were synthesized: pre-P9: The operation is the same as in Example 2. β -methyl- d -Velolactone (11.1 g, 97.0 mmol), α -furanmethyl- d -Velolactone (0.54 g, 3.0 mmol), 1,4-benzenedimethanol (0.0069 g, 0.05 mmol) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (0.0139 g, 0.1 mmol).

[0034] pre-P9 pre-P10: The operation is the same as in Example 2. α -Ethyl- d -Velolactone (12.4 g, 97.0 mmol), α -furanmethyl- d -Velolactone (0.54 g, 10.0 mmol), 1,4-benzenedimethanol (0.0069 g, 0.05 mmol) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (0.0139 g, 0.1 mmol).

[0035] pre-P10 (2) Preparation of cross-linked elastomers: The above prepolymers were respectively combined with N , N -(4,4-methylenediphenyl)bismaleimide was crosslinked according to the method in Example 4 to prepare elastomers P9 and P10.

[0036] (3) Performance characterization: The mechanical and thermal properties of the two elastomers were tested, and the results are as follows:

[0037] Example 8: Polymer Depolymerization and Recycling The elastomer P2 (2.00 g) prepared in Example 4 was pulverized and placed in a 50 mL round-bottom flask with anhydrous zinc chloride (ZnCl2, 0.10 g, 0.73 mmol). The mixture was heated to 120 °C on a rotary evaporator. Volatile monomers continuously evaporated and were collected in a receiving flask via a condenser. After 6 h, the reaction was complete, and 1.89 g of a colorless, transparent liquid was collected. Gas chromatography (GC) analysis confirmed that it contained... α -methyl- d -Velolactone, α -furanmethyl- d The recoveries of the two main components, valproic acid and valproic acid, were 97% and 94%, respectively, calculated by the area normalization method. Figure 5 The degradation products and α -methyl- d -Velolactone, α -furanmethyl- d Comparison of 1H NMR spectra of valproic acid.

[0038] Comparative Example 1: Comparison of Non-Polyester Main Chains To illustrate the crucial role of the feature of "polymer backbone originating from the ring-opening polymerization of lactone monomers" in achieving efficient chemical cycling in this invention, a non-depolymerizable polyacrylate backbone was selected for comparison in this comparative example. A poly(n-butyl acrylate-co-methyl furan acrylate) prepolymer pre-PA1 containing furan groups (~8.5 mol%) in the side chains was synthesized via free radical copolymerization, and the exact same conditions as those in this invention were used. N , NDA-crosslinked elastomer PA1 was prepared by heat treatment at 70°C using (4,4-methylenediphenyl)bismaleimide crosslinking agent. Under the same depolymerization conditions (120°C, ZnCl2 catalysis), PA1 did not undergo the clear selective depolymerization and monomer evaporation process seen in the elastomer of this invention. The final product was a brownish-black viscous gel, and GC-MS analysis showed that it was a complex mixture of dozens of low-molecular-weight fragments, with a primary monomer recovery rate of less than 5%. This result demonstrates that dynamic DA crosslinking alone cannot ensure high-selectivity recycling; the ester bonds unique to the polyester backbone, which can be directionally broken under mild conditions, and the reversibility of dynamic bonds produce a crucial synergistic effect, which is a necessary condition for achieving efficient and highly selective regeneration of the primary monomer from the crosslinked network. Therefore, the "polyester backbone" is an indispensable key technical feature in the core inventive concept of achieving a high-quality closed-loop chemical cycle of "monomer → material → monomer" in this invention.

Claims

1. A polyester-based chemically recyclable crosslinkable elastomer, characterized in that, This polyester-based chemically cyclic crosslinkable elastomer is obtained by uniformly mixing a furan-containing polyester with a crosslinking agent and carrying out a Diels-Alder reaction.

2. The polyester-based chemically recyclable crosslinkable elastomer according to claim 1, characterized in that, The structural formula of the polyester containing furan groups is: ； in, R 1 R 2 R 3 R 4 R 5 R 6 Selected from hydrogen, Alkyl groups with 1 to 20 carbon atoms, R 1 R 2 R 3 R 4 R 5 R 6 Same or different; R 1 R 2 R 3 R 4 R 5 R 6 At least one is a is 1, 2, or 3; b is 0, 1, 2, or 3; x is an integer between 0 and 10; The structural formulas for A, B, and C are: ； R 7 R 8 R 9 R 10 R 11 R 12 Selected from hydrogen, alkyl groups with 1 to 20 carbon atoms, R 7 R 8 R 9 R 10 R 11 R 12 Same or different; c is 1, 2 or 3; d is 0, 1, 2 or 3; A, B, and C may be the same or different; m is an integer between 1 and 10000, n is an integer between 10 and 10000; o and p are integers between 0 and 10000.

3. The polyester-based chemically recyclable crosslinkable elastomer according to claim 1, characterized in that, The crosslinking agent is a bismaleimide compound linked by bridging groups, and its structural formula is: ； Among them, R 13 It consists of subunits containing 1-40 carbon alkane or aromatic hydrocarbons.

4. The polyester-based chemically recyclable crosslinkable elastomer according to claim 3, characterized in that, The crosslinking agent is: 、 、 、 、 、 、 。 5. A method for preparing a polyester-based chemically cyclic crosslinkable elastomer, characterized in that, Includes the following steps: S1, Synthesis of furan group polyesters; Furanyl lactone monomer 1 and one or more lactone monomers 2 are dissolved in a first organic solvent with or without an initiator. The molar ratio of monomer 1 to monomer 2 is 1:0.01 to 1:1000. The mixture is stirred at room temperature for 5 minutes. Then, a catalyst is added. The molar ratio of the catalyst to furanyl lactone monomer 1 is 1:10 to 1:10000. When the conversion rates of furanyl lactone monomer 1 and lactone monomer 2 remain unchanged, water or an acidic substance is added to terminate the reaction. A second organic solvent is added to precipitate the polymer. The precipitate is filtered, washed, and dried to obtain furanyl polyester. S2, crosslinking of furanyl polyester; The furan-based polyester obtained in step S1 is dissolved in a third organic solvent, and then a crosslinking agent is added. The molar ratio of furan groups in the furan-based polyester to the crosslinking agent is 1:0.01 to 1:

100. The mixture is stirred at room temperature for 0.1 to 12 hours to ensure uniform mixing. Subsequently, the solvent is removed in a mold, and the resulting solid is placed under heating conditions of 40 to 100°C for 0.1 to 24 hours to allow the furan groups and maleimide groups to undergo a Diels-Alder reaction, forming a dynamic covalent crosslinking network, and finally obtaining a polyester-based chemically cyclic crosslinkable elastomer.

6. The preparation method according to claim 5, characterized in that, The structural formula of furanyl lactone monomer 1 is: ； The structural formula of lactone monomer 2 is: ； The catalyst is a metal catalyst, an organic catalyst, or an inorganic catalyst.

7. The preparation method according to claim 6, characterized in that, The metal catalyst is Ln(OR) 14 )3, Ln(CH2SiMe3)(THF)x, Ln[N(SiMe3)2], M(OR 14 )2, M(CH2SiMe3)2 or M[N(SiMe3)2]2, wherein Ln is selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Td, Dy, Ho, Er, Tm, Yb, Sc, Y and Lu; M is selected from Zn and Mg; R 14 Selected from alkyl groups of 1 to 20 carbon atoms, aryl groups of 6 to 24 carbon atoms, and olefins of 2 to 12 carbon atoms; Me is methyl; The organic catalyst is an organic base or an organic acid, wherein the organic acid is diphenyl phosphate, and the organic base is: ； Among them, R 15 R 16 R 17 Selected from hydrocarbon groups with 1 to 20 carbon atoms, R 15 R 16 R 17 Same or different; The inorganic catalyst is sodium alkoxide containing 1 to 40 carbon atoms or potassium alkoxide containing 1 to 40 carbon atoms.

8. The preparation method according to claim 5, characterized in that, The initiator is any one of monohydric alcohols, dihydric alcohols, polyhydric alcohols, thiols, and amines containing 1 to 40 carbon atoms; The acidic substance is at least one of acetic acid, benzoic acid, hydrochloric acid, sulfuric acid, and phosphoric acid; The first organic solvent is at least one of benzene, toluene, ethylbenzene, hexane, heptane, octane, tetrahydrofuran, diethyl ether, petroleum ether, chloroform, dichloromethane, and N,N-dimethylformamide; The second organic solvent includes at least one of hexane, heptane, octane, tetrahydrofuran, diethyl ether, petroleum ether, methanol, and ethanol; The third organic solvent includes dichloromethane, tetrahydrofuran, toluene, ethylbenzene, ethyl acetate, acetonitrile, etc. N , N At least one of dimethylformamide; When water or acidic substances are added to terminate the polymerization reaction, the amount of water or acidic substances added is 1 to 10 times the equivalent of the catalyst.

9. A method for depolymerizing a polyester-based chemically cyclic crosslinkable elastomer, characterized in that, Polyester-based chemically recyclable crosslinkable elastomers were pyrolyzed in the presence of a Lewis acid catalyst at a temperature range of 90–300 °C and a vacuum degree of 0.01–760 mmHg to recover furanyl lactone monomer 1 and lactone monomer 2.

10. The depolymerization method according to claim 9, characterized in that, The Lewis acid catalyst includes at least one of zinc chloride, zinc acetate, magnesium chloride, ferric chloride, ferrous chloride, stannous octoate, and zinc acetate.

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