Full-bio-based heterocyclic monomer and method for regulating and controlling molecular weight of furyl polyester by using full-bio-based heterocyclic monomer

Abstract

The invention relates to the technical field of full-bio-based polyester synthesis, in particular to a full-bio-based heterocyclic monomer which is obtained by mixing equol, DMAP and undecylenic acid for reaction, the molar ratio of equol to DMAP is 1: (1-1.2), and the molar ratio of equol to undecylenic acid is 1: (1-1.2). The invention also discloses a method for regulating and controlling the molecular weight of furyl polyester by adopting the full-bio-based heterocyclic monomer. According to the full-bio-based heterocyclic monomer and the method for regulating and controlling the molecular weight of the furyl polyester, the furyl polyester with the adjustable molecular weight is prepared through rearrangement moving ring-chain balance of a carbon-carbon double bond along a main chain. A heterocyclic monomer can generate an unsaturated polyolefin structure in a copolymerization process, and the polyolefin realizes rearrangement of carbon-carbon double bonds along a main chain through closed-loop depolymerization double decomposition, so that ring-chain balance is shifted, unsaturated polyolefin structural units are alternately integrated in a furyl polyester skeleton, and polyester molecular weight adjustment is successfully realized.

Description

Technical Field

[0001] This invention relates to the field of fully bio-based polyester synthesis technology, and in particular to a fully bio-based heterocyclic monomer and a method for controlling the molecular weight of furan-based polyesters. Background Technology

[0002] Polyethylene furanate (PEF) is a representative bio-based polyester in the furanate polyester family, copolymerized from furanate dicarboxylic acid (FDCA) and ethylene glycol (EG). Compared to petroleum-based polyethylene terephthalate (PET), PEF possesses superior thermal and mechanical properties and a higher glass transition temperature. If PEF is continuously polymerized and spun, it holds promise as a replacement for PET fiber, my country's largest chemical fiber product. However, to ensure good spinnability and mechanical properties, the polyester molecular weight distribution should be narrow, i.e., concentrated molecular weight with a low polydispersity index (PDI). Typically, PEF has a wide molecular weight distribution (PDI > 3), which severely impacts the stability of the spinning process and the product's usability and processing performance. Therefore, controlling the polyester molecular weight and reducing the molecular weight distribution (PDI) is the development goal of fiber-grade furanate dicarboxylic acid polyesters.

[0003] Currently, molecular weight can usually be controlled by changing the polymerization method or the catalyst, but this can lead to problems such as polyester becoming brittle, harsh reaction conditions, and high energy consumption. Moreover, the catalyst has a significant impact on color change and molecular weight increase during the polymerization process. Summary of the Invention

[0004] To address the shortcomings of the aforementioned technologies, this invention provides a fully bio-based heterocyclic monomer and a method for regulating the molecular weight of furan-based polyesters, thereby improving the regulation of the molecular weight of furan-based polyesters and reducing their polydimer (PDI).

[0005] This invention discloses a fully bio-based heterocyclic monomer obtained by the mixed reaction of equol, DMAP and undecenoic acid, wherein the molar ratio of equol to DMAP is 1:1-1.2 and the molar ratio of equol to undecenoic acid is 1:1-1.2.

[0006] The fully bio-based heterocyclic monomer was prepared by the following method: estrol, DMAP, and undecenoic acid were dissolved in dichloromethane and reacted with stirring at room temperature for 12-18 h. The resulting mixture was collected, washed, and dried to obtain the fully bio-based heterocyclic monomer, denoted as M, wherein the drying temperature was 40-100℃.

[0007] A method for controlling the molecular weight of furan-based polyester using the above-mentioned fully bio-based heterocyclic monomers comprises the following steps: First, FDCA, EG, M, Sb2O3, and Grubbs 1 are added to a flask, and the system is heated to 180-220℃ for esterification. Next, the system is heated to 200-230℃, the vacuum is reduced to 1000 Pa, and the pressure is maintained for at least 1 hour for pre-condensation reaction. Finally, during the final condensation reaction, the temperature of the reaction system is raised to 220-240℃, the vacuum is reduced to below 100 Pa, and the reaction ends when the rod-climbing effect is obvious. The final product is collected and denoted as furan-based polyester.

[0008] The molar ratio of FDCA to EG is 1:1.01-1.8, the mass ratio of Sb2O3 to FDCA is 0.0001-0.02:1, the mass ratio of M to FDCA is 0.1-0.3:1, and the mass ratio of Grubbs1 to M is 0.01:1.

[0009] The esterification reaction is carried out under inert gas protection for 1-3 hours.

[0010] The vacuum level of the reactor for the final polycondensation reaction is reduced to below 50 Pa, and the pressure is maintained for no less than 3 hours.

[0011] The combined time for the pre-condensation reaction and the final condensation reaction is 2-6 hours.

[0012] Furan-based polyester fibers are prepared using a low-speed spinning process, with the front and rear hot roller temperatures at 50°C and 90°C respectively during drawing, and a draw ratio of 2.7.

[0013] This invention discloses a fully bio-based heterocyclic monomer and a method for regulating the molecular weight of furan-based polyesters. The method involves shifting the ring-chain equilibrium through the rearrangement of carbon-carbon double bonds along the main chain to prepare furan-based polyesters with adjustable molecular weight. The heterocyclic monomer can generate unsaturated polyolefin structures during copolymerization. These polyolefins achieve carbon-carbon double bond rearrangement along the main chain through ring-closure depolymerization and metathesis, thereby shifting the ring-chain equilibrium. Unsaturated polyolefin structural units are alternately integrated into the furan-based polyester backbone, successfully achieving molecular weight regulation. The resulting furan-based polyesters have a molecular weight distribution (PDI) of 2.2-2.6, a number-average molecular weight (Mn) of 27200-29400 g / mol, a fiber linear density of 141.8 dtex-167.2 dtex, a breaking strength of 28.1±1-55.4±3 cN·dtex, and a breaking elongation of 37±11-211±9%.

[0014] Therefore, a fully bio-based heterocyclic monomer was prepared using equol and castor oil derivative catalysts. This monomer was then copolymerized to generate soft-segment unsaturated polyolefins. Furthermore, by shifting ring-chain equilibrium, quantitative preparation of furanyl polyesters through forward polymerization and reverse depolymerization was achieved. This method holds promise for updating existing methods for controlling the molecular weight of bio-based polyesters and demonstrates broad practical application prospects. Attached Figure Description

[0015] Figure 1 The preparation route of the fully bio-based heterocyclic monomer of the present invention is as follows;

[0016] Figure 2 This is the design route for regulating the molecular weight of PEF using the heterocyclic monomer M of the present invention;

[0017] Figure 3 The stress-strain curves are for filaments based on furan-based polyester. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0019] Example 1:

[0020] like Figure 1 As shown, this invention discloses a fully bio-based heterocyclic monomer. First, 0.331 g (1.368 mmol) of estrol, 0.168 g (1.368 mmol) of DMAP, and 0.252 g (1.370 mmol) of undecenoic acid were dissolved in 50 mL of dichloromethane. The mixture was stirred and reacted at room temperature for 12 h. The resulting mixture was collected, washed, dried, and designated as the fully bio-based heterocyclic monomer M1.

[0021] Example 2:

[0022] This invention discloses a fully bio-based heterocyclic monomer. First, 0.29 g of estrol (1.2 mmol), 0.168 g (1.368 mmol) of DMAP, and 0.378 g (2.055 mmol) of undecenoic acid were dissolved in 50 mL of dichloromethane. The mixture was stirred and reacted at room temperature for 14 h. The resulting mixture was collected, washed, dried, and designated as the fully bio-based heterocyclic monomer M2.

[0023] Example 3:

[0024] This invention discloses a fully bio-based heterocyclic monomer. First, 0.662 g of estrol (2.756 mmol), 0.193 g (3.169 mmol) of DMAP, and 0.507 g (2.756 mmol) of undecenoic acid were dissolved in 50 mL of dichloromethane. The mixture was stirred and reacted at room temperature for 16 h. The resulting mixture was collected, washed, dried, and designated as the fully bio-based heterocyclic monomer M3.

[0025] Example 4:

[0026] This invention discloses a fully bio-based heterocyclic monomer. First, 0.662 g of estrol (2.756 mmol), 0.193 g (3.169 mmol) of DMAP, and 0.608 g (3.3072 mmol) of undecenoic acid were dissolved in 50 mL of dichloromethane. The mixture was stirred and reacted at room temperature for 18 h. The resulting mixture was collected, washed, dried, and designated as the fully bio-based heterocyclic monomer M4.

[0027] Example 5:

[0028] This invention discloses a method for controlling the molecular weight of furan-based polyesters using the fully bio-based heterocyclic monomer obtained in Example 1. The specific steps are as follows.

[0029] All synthesis operations of furanyl polyesters were carried out in a three-necked round-bottom flask equipped with a polytetrafluoroethylene (PTFE) stirrer and under continuous mechanical stirring. First, 0.1 mol (15.609 g) FDCA, 0.101 mol (6.269 g) EG, 0.0156 g Sb₂O₃, 1.561 g M₁, and 0.015 g Grubbs 1 were added to a 100 mL four-necked flask. To ensure the reaction was sealed, the ports were sealed with vacuum silicone ester, and the flask was placed in an oil bath for heating. Next, after stirring at 110 °C for 0.5 h, the temperature was increased to 180 °C and reacted for 2 h. Subsequently, the vacuum was reduced from atmospheric pressure to 1000 Pa, and the reaction was continued at 200 °C for 1 h. Finally, at 220 °C, the vacuum was reduced to below 50 Pa, and the reaction was continued for 2 h. Finally, N₂ was introduced into the system to increase the internal pressure to 0.2 MPa, and the bottom temperature and casting head temperature were set to 220 °C. Subsequently, the temperature was raised to 240℃ for further melting and depolymerization. After a 1-hour interval, the polymer melt was water-cooled and granulated using a pelletizer. It was then dried and sealed for storage, designated as furan-based polyester S1. The PDI of furan-based polyester S1 in its molten state, obtained by extrusion using an inert gas precipitator, was 2.6, and the Mn content was 27200 g / mol. Its spun fiber linear density was 141.8 dtex, its breaking strength was 28.1 ± 1 cN·dtex, and its elongation at break was 67 ± 3%.

[0030] Example 6:

[0031] This invention discloses a method for regulating the molecular weight of furan-based polyesters using the fully bio-based heterocyclic monomer obtained in Example 2. The specific steps are as follows.

[0032] All synthesis operations of furanyl polyesters were carried out in a three-necked round-bottom flask equipped with a polytetrafluoroethylene (PTFE) stirrer and under continuous mechanical stirring. First, 0.3 mol (46.827 g) FDCA, 0.101 mol (24.827 g) EG, 0.05 g Sb₂O₃, 9.365 g M₂, and 0.09 g Grubbs were added to a 100 mL four-necked flask. To ensure the reaction was sealed, the ports were sealed with vacuum silicone ester, and the flask was heated in an oil bath. Next, the mixture was stirred at 110 °C for 0.5 h, then the temperature was increased to 180 °C and reacted for 2 h. Subsequently, the vacuum was reduced from atmospheric pressure to 1000 Pa, and the reaction was continued at 200 °C for 1 h. Finally, the vacuum was reduced to below 50 Pa at 220 °C, and the reaction was continued for 2 h. Finally, N₂ was introduced into the system to increase the internal pressure to 0.2 MPa, and the bottom temperature and casting head temperature were set to 220 °C. Subsequently, the temperature was raised to 240℃ for further melting and depolymerization. After a 1-hour interval, the polymer melt was water-cooled and granulated using a pelletizer, dried, and sealed for storage, designated as furan-based polyester S2. The PDI of furan-based polyester S2 in the molten state, obtained by extrusion using inert gas, was 2.42, and the Mn content was 28400 g / mol. Its spun fiber linear density was 161.8 dtex, its breaking strength was 42.7 ± 2 cN·dtex, and its elongation at break was 157 ± 7%.

[0033] Example 7:

[0034] This invention discloses a method for controlling the molecular weight of furan-based polyesters using the fully bio-based heterocyclic monomer obtained in Example 3. The specific steps are as follows.

[0035] All synthesis operations of furanyl polyesters were carried out in a three-necked round-bottom flask equipped with a polytetrafluoroethylene (PTFE) stirrer and under continuous mechanical stirring. First, 0.13 mol (20.29 g) FDCA, 0.16 mol (9.931 g) EG, 0.2029 g Sb₂O₃, 6.087 g M₃, and 0.06 g Grubbs 1 were added to a 100 mL four-necked flask. To ensure the reaction was sealed, the flask was sealed with vacuum silicone ester and heated in an oil bath. Next, after stirring at 110 °C for 0.5 h, the temperature was increased to 200 °C and reacted for 2 h. Subsequently, the vacuum was reduced from atmospheric pressure to 1000 Pa, and the reaction was continued at 210 °C for 2 h. Finally, at 230 °C, the vacuum was reduced to below 50 Pa, and the reaction was continued for 3 h. Finally, N2 was introduced into the system to increase the internal pressure to 0.2 MPa. The bottom temperature of the reactor and the casting head temperature were set to 240℃. Melting and depolymerization continued for 3 hours. The polymer melt was then water-cooled and granulated using a pelletizer, dried, and sealed for storage, and designated as furan-based polyester S3. The PDI of furan-based polyester S3 in the molten state, obtained by extrusion using inert gas, was 2.2, and the Mn content was 29400 g / mol. Its fiber linear density was 167.2 dtex, its tensile strength was 55.4 ± 3 cN·dtex, and its elongation at break was 211 ± 9%.

[0036] Example 8:

[0037] This invention discloses a method for controlling the molecular weight of furan-based polyesters using the fully bio-based heterocyclic monomer obtained in Example 4. The specific steps are as follows.

[0038] All synthesis operations of furanyl polyesters were carried out in a three-necked round-bottom flask equipped with a polytetrafluoroethylene (PTFE) stirrer and under continuous mechanical stirring. First, 0.13 mol (20.29 g) FDCA, 0.16 mol (9.931 g) EG, 0.2029 g Sb₂O₃, 5.073 g M₄, and 0.05 g Grubbs 1 were added to a 100 mL four-necked flask. To ensure the reaction was sealed, the flask was sealed with a vacuum silicone sealant and placed in an oil bath for heating. Next, after stirring at 110 °C for 0.5 h, the temperature was increased to 200 °C and reacted for 2 h. Subsequently, the vacuum was reduced from atmospheric pressure to 1000 Pa, and the reaction was continued at 210 °C for 2 h. Finally, at 230 °C, the vacuum was reduced to below 50 Pa, and the reaction was continued for 3 h. Finally, N2 was introduced into the system to increase the internal pressure to 0.2 MPa. The bottom temperature of the reactor and the casting head temperature were set to 240℃. Melting and depolymerization continued for 3 hours. The polymer melt was then water-cooled and granulated using a pelletizer, dried, and sealed for storage, and designated as furan-based polyester S4. The PDI of furan-based polyester S4 in the molten state, obtained by extruding with inert gas, was 2.37, and the Mn content was 28700 g / mol. Its spun fiber linear density was 157.1 dtex, its breaking strength was 47.9 ± 1 cN·dtex, and its breaking elongation was 172 ± 8%.

[0039] Example 9:

[0040] This invention discloses a method for controlling the molecular weight of furan-based polyesters using the fully bio-based heterocyclic monomer obtained in Example 4. The specific steps are as follows.

[0041] All synthesis operations of furanyl polyesters were carried out in a three-necked round-bottom flask equipped with a polytetrafluoroethylene (PTFE) stirrer and under continuous mechanical stirring. First, 0.1 mol (15.609 g) FDCA, 0.101 mol (6.269 g) EG, 0.0156 g Sb₂O₃, 2.26 g M₄, and 0.02 g Grubbs 1 were added to a 100 mL four-necked flask. To ensure the reaction was sealed, the ports were sealed with vacuum silicone ester, and the flask was heated in an oil bath. Next, after stirring at 110 °C for 0.5 h, the temperature was increased to 180 °C and reacted for 2 h. Subsequently, the vacuum was reduced from atmospheric pressure to 1000 Pa, and the reaction was continued at 200 °C for 1 h. Finally, at 220 °C, the vacuum was reduced to below 50 Pa, and the reaction was continued for 2 h. Finally, N₂ was introduced into the system to increase the internal pressure to 0.2 MPa, and the bottom temperature and casting head temperature were set to 220 °C. Subsequently, the temperature was raised to 240℃ for further melting and depolymerization. After a 1-hour interval, the polymer melt was water-cooled and granulated using a pelletizer, dried, and sealed for storage, designated as furan-based polyester S5. The PDI of furan-based polyester S5 in its molten state, obtained by extrusion using inert gas, was 2.51, and the Mn content was 27900 g / mol. Its fiber linear density was 151.1 dtex, tensile strength was 37.7 ± 1 cN·dtex, and elongation at break was 81 ± 5%.

[0042] Comparative Example 1 (Preparation of furanyl polyester S6)

[0043] Furan-based polyester was prepared using the same method as in Example 5, without the addition of M4. The resulting furan-based polyester S6 had a PDI of 3.78 and a Mn of 23700 g / mol, making it difficult to spin.

[0044] Comparative Example 2 (Preparation of high molecular weight furan-based polyester S7 using solid-state polycondensation)

[0045] Using the same method as in Example 4, without adding M4, solid-state polycondensation was carried out after polymerization. The resulting furan-based polyester S7 had a PDI of 3.51 and a Mn of 41900 g / mol, making it difficult to spin.

[0046] Table 1. Performance data of furanyl polyester and its spun fibers

[0047]

[0048]

[0049] Based on the experimental results and comparing the examples and comparative examples, a furan-based polyester with adjustable molecular weight was prepared by rearranging carbon-carbon double bonds along the main chain to achieve ring-chain equilibrium. The lowest PDI was 2.2, and the highest Mn was 29400 g / mol. The maximum breaking strength of the spun fiber filament was 55.4 ± 3 cN·dtex, and the highest breaking elongation was 211 ± 9%. The method described in this invention can significantly reduce PDI and significantly improve the spinnability of furan-based polyesters while ensuring mechanical properties.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simplification, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A fully bio-based heterocyclic monomer, characterized in that: It is obtained by reacting equol, DMAP and undecenoic acid, wherein the molar ratio of equol to DMAP is 1:1-1.2 and the molar ratio of equol to undecenoic acid is 1:1-1.

2.

2. The all-bio-based heterocyclic monomer according to claim 1, characterized in that: It is prepared by the following method: estrol, DMAP and undecenoic acid are dissolved in dichloromethane and stirred at room temperature for 12-18 h. The resulting mixture is collected, washed and dried to obtain a fully bio-based heterocyclic monomer, denoted as M, wherein the drying temperature is 40-100℃.

3. A method for controlling the molecular weight of furan-based polyesters using the fully bio-based heterocyclic monomer as described in claim 2, characterized in that: The specific steps are as follows: First, add FDCA, EG, M, Sb2O3, and Grubbs 1 to a flask, heat the system to 180-220℃ for esterification reaction, then heat the system to 200-230℃, reduce the vacuum to 1000Pa, and maintain the pressure for at least 1 hour for pre-condensation reaction; finally, during the final condensation reaction, raise the temperature of the reaction system to 220-240℃, reduce the vacuum to below 100Pa, and wait until the climbing effect is obvious, the reaction ends, collect the final product, and record it as furanyl polyester.

4. The method for regulating the molecular weight of furan-based polyesters using a fully bio-based heterocyclic monomer according to claim 3, characterized in that: The molar ratio of FDCA to EG is 1:1.01-1.8, the mass ratio of Sb2O3 to FDCA is 0.0001-0.02:1, the mass ratio of M to FDCA is 0.1-0.3:1, and the mass ratio of Grubbs 1 to M is 0.01:

1.

5. A method for regulating the molecular weight of furan-based polyesters using a fully bio-based heterocyclic monomer according to claim 3, characterized in that: The esterification reaction is carried out under inert gas protection for 1-3 hours.

6. A method for regulating the molecular weight of furan-based polyesters using a fully bio-based heterocyclic monomer according to claim 3, characterized in that: The vacuum level of the reactor for the final polycondensation reaction is reduced to below 50 Pa, and the pressure is maintained for no less than 3 hours.

7. A method for regulating the molecular weight of furan-based polyesters using a fully bio-based heterocyclic monomer according to claim 6, characterized in that: The combined time for the pre-condensation reaction and the final condensation reaction is 2-6 hours.

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