Furyl-based polyamides based on ionic liquid catalysis and methods for their preparation

Abstract

This invention discloses a furan-based polyamide based on ionic liquid catalysis and its preparation method. Using bio-based dimethyl furanate and 1,4-butanediamine as monomers and an ionic liquid as catalyst, furan-based polyamide, specifically poly(dimethyl furanate-butanediamine), is obtained through direct melt polycondensation. The entire synthesis process uses only water as a solvent, eliminating the need for any organic solvents or additives. This solves the problems of uneven heat and mass transfer and product molecular weight distribution during the reaction, and avoids altering the physicochemical parameters of monomers and amine salts during polymerization due to the introduction of organic solvents and additives, thus preventing disruption of the entire polymerization process. This invention uses an ionic liquid as a catalyst, resulting in a reaction system with high catalytic efficiency and no metals. The obtained product has high molecular weight and good performance, meeting the requirements of green, environmentally friendly, and recyclable bio-based polymer materials.

Description

Technical Field

[0001] This invention belongs to the field of bio-based polymer materials, specifically relating to a bio-based polyamide based on ionic liquid catalysis and its preparation method, particularly to a polyfuran dicarboxylate based on ionic liquid catalysis and its preparation method. Background Technology

[0002] Polyamide is a polymer containing amide bonds in repeating units, exhibiting excellent chemical stability and mechanical properties. As an important engineering plastic, polyamide is widely used in the petroleum industry, automotive industry, machinery, shipbuilding, electronics, medical devices, and household appliances. Due to its superior comprehensive properties, polyamide has become the most widely used thermoplastic engineering plastic both domestically and internationally, and is also the world's second largest fiber material after polyester fiber. However, current traditional polyamide synthesis heavily relies on fossil resources, such as aromatic / aliphatic dicarboxylic acids, diamines, amino acids, and lactams. The rapid depletion of fossil resources and increasingly serious environmental problems have drawn widespread attention to bio-based polymers. Furan-based polyamides, derived from biomass, are semi-aromatic polyamides that simultaneously possess the good processability of aliphatic polyamides and the heat resistance of aromatic polymers, showing broad application prospects.

[0003] 2,5-Furandicarboxylic acid (FDCA) is prepared from biomass and its derivatives using chemical or biological methods. Compared to petroleum-based aromatic terephthalic acid (TPA), bio-based FDCA exhibits better biodegradability and unique properties due to its reduced carbon atom count and lower aromaticity, and has been recognized as one of the 12 most valuable bio-based platform compounds. Since the 1960s, FDCA has been used to prepare polyamides, breaking the traditional dependence of the polyamide synthesis industry on petroleum resources and reducing the production and emission of hazardous waste.

[0004] Poly(furandibutylamine) (PA4F) possesses thermal and mechanical properties similar to, or even better than, those of terephthalic acid (TPA) / isophthalic acid (IPA) based polymers. Therefore, FDCA-based furan-aliphatic polyamides can serve as a substitute for polyphthalamides and have broad application prospects in future industrial fields as high-performance materials. However, current research on polyamide PA4F, both domestically and internationally, mainly focuses on copolymerization and thermal degradation, and is far from reaching the level of industrially scalable processes.

[0005] Ionic liquids are a class of widely used green catalysts. In recent years, they have attracted widespread attention due to their unique physicochemical properties, such as near-zero vapor pressure, high thermal stability, structural tunability, and low toxicity. In the preparation of polyamides, high molecular weight aromatic polyamides have been successfully synthesized using imidazole-based ionic liquids as solvents. They hold promise as excellent catalysts in polymer preparation, offering advantages over traditional catalysts such as high catalytic efficiency and the absence of metal residues, thus avoiding environmental pollution and harm to human health caused by residual metals in the final product. Therefore, the preparation of bio-based polyamides using ionic liquids is an important pathway to achieving non-metallic catalysis.

[0006] Furthermore, in existing PA4F synthesis processes, the raw materials are typically first salted in methanol / ethanol, followed by pressurized prepolymerization and depressurized polymerization using water as the reaction medium. After obtaining a polymer of a certain molecular weight, melt polycondensation or solid-state polycondensation is then performed. This process is cumbersome, requires sophisticated equipment, has poor atom economy, and generates a large amount of waste liquid. Therefore, developing a green, environmentally friendly, and efficient process for preparing high-performance furanyl polyamide PA4F is particularly important. Summary of the Invention

[0007] This invention addresses the shortcomings of existing processes by providing a furanyl polyamide based on ionic liquid catalysis and its preparation method. The entire reaction process of this invention uses only water as the dispersion phase and heating medium, eliminating the need for any organic solvents or additives, thus aligning with the green and environmentally friendly concept of bio-based polymer materials. Initially, pressure prepolymerization is used to prevent the volatilization of the diamine, followed by removal of the water solvent under vacuum conditions. Finally, melt polycondensation yields a polymer with a number-average molecular weight of 9642–27229 g / mol. The bio-based polyamide synthesis method based on ionic liquid catalysis provided by this invention is convenient, rapid, and has a wide range of applications. The resulting polymer exhibits excellent overall properties, including a high glass transition temperature, high transparency, and good thermal stability.

[0008] To achieve the above-mentioned objectives, the specific technical solution of this invention is as follows:

[0009] A furanyl polyamide based on ionic liquid catalysis and its preparation method are characterized in that: dimethyl furanate and 1,4-butanediamine are reacted via melt polycondensation using an ionic liquid as a catalyst to prepare a bio-based polyamide, specifically, the preparation of bio-based polyfuranylbutanediamine includes the following steps:

[0010] (1) Prepolymerization stage: Dimethyl furanate, deionized water and ionic liquid catalyst are mixed in a certain proportion and 1,4-butanediamine is added. The above solution is transferred into a high-pressure reactor, and nitrogen is repeatedly purged to replace the atmosphere in the reactor with an inert atmosphere. Then the reactor is heated and pressurized to obtain an oligomer solution.

[0011] (2) Polycondensation stage: The obtained oligomer solution is vacuumed at a certain temperature to remove water and by-product methanol from the system, and then the temperature is raised to carry out melt polycondensation.

[0012] The melt polycondensation reaction is carried out in four stages. The first stage is pressurized prepolymerization: nitrogen is used to pressurize to 0.1-0.4 MPa, the stirring rate is 300-800 rpm, the reaction temperature is 80-120℃, and the reaction time is 30-150 min. The second stage is heat and pressure holding: the reaction temperature is 120-190℃, and the reaction time is 60-300 min, to obtain an oligomer solution. The third stage is dehydrated under reduced pressure: the reaction temperature is 80-160℃, the stirring rate is 50-200 rpm, the reaction time is 60-360 min, and the vacuum degree is 1000-6000 Pa. The fourth stage is melt polycondensation: the reaction temperature is 190-260℃, the vacuum degree is controlled within 100 Pa, the stirring rate is 50-150 rpm, and the reaction time is 120-360 min.

[0013] The reaction equation for the synthesis of furanyl polyamide PA4F from dimethyl furanyl dicarboxylate (DMFDC) and 1,4-butanediamine (BDA) in this invention is as follows:

[0014]

[0015] The furanyl polyamide based on ionic liquid catalysis and its preparation method are characterized in that the total mass ratio of dimethyl furanate and 1,4-butanediamine to deionized water is 1:0.2-1.5, and the monomer molar ratio of dimethyl furanate and 1,4-butanediamine is 1:0.95-1.1.

[0016] The aforementioned furanyl polyamide based on ionic liquid catalysis and its preparation method are characterized in that the ester-amine exchange and polycondensation catalysts are 1-butyl-3-methylimidazolium phosphate ([Bmim][H2PO4]), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]), 1-butyl-3-methylimidazolium chlorate ([Bmim]Cl), 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF6]), and 1-butyl-3-methylimidazolium acetate ([Bmim][CH3COO]), and the catalyst dosage is 0.1% of the total mass of the reactants. ～ 1.5 wt%.

[0017] The furanyl polyamide based on ionic liquid catalysis and its preparation method are characterized in that, before pressurized prepolymerization, nitrogen gas is used for pressurization at 0.1-0.4 MPa.

[0018] The furanyl polyamide based on ionic liquid catalysis and its preparation method are characterized in that the prepolymerization stage is kept at a temperature of 120-190℃.

[0019] The furanyl polyamide based on ionic liquid catalysis and its preparation method are characterized in that the dehydration temperature under reduced pressure before melt polycondensation is 80-160℃.

[0020] The aforementioned furanyl polyamide based on ionic liquid catalysis and its preparation method are characterized in that the molecular formula of the prepared polyfurandiformylbutane is [missing information]. Where n is an integer, and its number-average molecular weight is 9642–27229 g / mol.

[0021] The aforementioned furanyl polyamide based on ionic liquid catalysis and its preparation method are characterized in that the glass transition temperature of the polyfuran dicarboxylate is 121–151 °C.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) The furanyl PA4F prepared by this invention is a bio-based polymer material. The raw materials used can be entirely derived from biomass, which is conducive to reducing the dependence of the current traditional polyamide industry on fossil resources and provides a new idea for the sustainable development of the polyamide industry.

[0024] (2) The maximum number-average molecular weight of PA4F synthesized by existing technology is 10,000 g / mol, and the molecular weight needs to be further improved; while the present invention uses imidazole ionic liquid as catalyst to prepare polyamide PA4F, and the obtained polymer has a number-average molecular weight of 27,229 g / mol, which is much better than the molecular weight of PA4F obtained by existing synthesis technology.

[0025] (3) The technology of this invention uses only water as the reaction medium in the synthesis process and does not add any other organic solvents, which is green and environmentally friendly and in line with the principle of sustainable development of bio-based polymer materials. The preparation of bio-based polyamide PA4F by direct melt polycondensation simplifies the polyamide preparation process.

[0026] (4) The present invention first ensures the ester-amine ratio under pressure, and then ensures the degree of polymerization of the prepolymer by controlling the reaction temperature and reaction time. Under suitable reaction temperature, the decarboxylation of dimethyl furanate and the thermal degradation of furan ring will not be caused. At the same time, the closed reaction vessel prevents the escape of monomer small molecules. Attached Figure Description

[0027] Figure 1 The furanyl polyamide PA4F obtained in specific embodiment 1 of the present invention 1 H-NMR.

[0028] Figure 2 The furanyl polyamide PA4F obtained in specific embodiment 1 of the present invention 13 C-NMR.

[0029] Figure 3 The TGA curve of furanyl polyamide PA4F obtained in specific embodiment 1 of the present invention is shown.

[0030] Figure 4 The image shows the DSC curve of furanyl polyamide PA4F obtained in specific embodiment 1 of the present invention. Detailed Implementation

[0031] The present invention will be further illustrated below with specific examples. However, the scope of protection of the present invention is not limited thereto. All equivalent changes and modifications made within the scope of the present invention patent should be included in the scope of the present invention.

[0032] In the examples below, the molecular weight of the polymer was determined by gel permeation chromatography (GPC) using polymethyl methacrylate as a standard. The mobile phase was hexafluoroisopropanol (containing 5 mmol / L sodium trifluoroacetate). The initial decomposition temperature and residual carbon content were tested using TG-60H. The glass transition temperature Tg was tested using a differential thermal calorimeter (DSC1). The test methods were based on the literature (Acta Polymerica Sinica, 2014(2):233-238).

[0033] Example 1: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.23 g of [Bmim][H2PO4] ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times, then pressurized to 0.4 MPa, and the stirring speed was adjusted to 800 rpm. The reaction was carried out at 80 °C for 60 min, and then the temperature was increased to 150 °C for 180 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the reactor pressure and remove methanol produced by ester-amine exchange. Then the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min. After that, the temperature was raised to 230℃ and held for 360 min to obtain PA4F, with Mn = 27229 g / mol, Mw = 61080 g / mol, PD = 2.24, and Tg = 151℃.

[0034] Example 2: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.23 g of [Bmim][H2PO4] ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times until the pressure reached 0.4 MPa. The magnetic stirring speed was adjusted to 800 rpm, and the reaction was carried out at 80 °C for 60 min. Then, the temperature was increased to 130 °C and the reaction was carried out for 180 min. After the reaction, the temperature was maintained at 80 °C for 60 min, and the mechanical stirring speed was 50 rpm. Nitrogen gas was introduced to restore the pressure of the reactor and remove methanol produced by ester-amine exchange. Then, the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min, followed by raising the temperature to 230℃ and holding for 360 min to obtain PA4F, with Mn = 21116 g / mol, Mw = 55316 g / mol, PD = 2.62, and Tg = 149℃.

[0035] Example 3: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.23 g of [Bmim][H2PO4] ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times until the pressure reached 0.4 MPa. The stirring speed was adjusted to 800 rpm, and the reaction was carried out at 80 °C for 60 min. Then, the temperature was increased to 190 °C and the reaction was carried out for another 60 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the pressure of the reactor and remove methanol produced by ester-amine exchange. Then, the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min, followed by a rise to 230℃ and a holding time of 360 min. PA4F was obtained, with Mn = 16679 g / mol, Mw = 30316 g / mol, PD = 1.81, and Tg = 132℃.

[0036] Example 4: 13.81 g of dimethyl furanate, 6.61 g of 1,4-butanediamine, 0.23 g of [Bmim][H2PO4] ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times until the pressure reached 0.4 MPa. The stirring speed was adjusted to 800 rpm, and the reaction was carried out at 80 °C for 60 min. Then, the temperature was increased to 150 °C and the reaction was carried out for 180 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the pressure of the reactor and remove methanol produced by ester-amine exchange. Then, the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, the temperature was raised to 190℃ and held for 120 min, and then the temperature was raised to 230℃ and held for 360 min to obtain PA4F, with Mn = 14825 g / mol, Mw = 33688 g / mol, PD = 2.27, and Tg = 127℃.

[0037] Example 5: 13.12 g of dimethyl furanate, 6.61 g of 1,4-butanediamine, 0.23 g of [Bmim][H2PO4] ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times until the pressure reached 0.4 MPa. The stirring speed was adjusted to 800 rpm, and the reaction was carried out at 80 °C for 60 min. Then, the temperature was increased to 150 °C and the reaction was carried out for 180 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the pressure of the reactor and remove methanol produced by ester-amine exchange. Then, the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min, followed by raising the temperature to 230℃ and holding for 360 min to obtain PA4F, with Mn = 23359 g / mol, Mw = 42859 g / mol, PD = 1.79, and Tg = 144℃.

[0038] Example 6: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.23 g of [Bmim][H2PO4] ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times until the pressure reached 0.4 MPa. The stirring speed was adjusted to 800 rpm, and the reaction was carried out at 80 °C for 60 min. Then, the temperature was increased to 190 °C and the reaction was carried out for 360 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the pressure of the reactor and remove methanol produced by ester-amine exchange. Then, the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, the temperature was raised to 190℃ and held for 120 min, and then the temperature was raised to 230℃ and held for 360 min to obtain PA4F, with Mn = 9642 g / mol, Mw = 25594 g / mol, PD = 2.65, and Tg = 121℃.

[0039] Example 7: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.23 g of [Bmim]Cl ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times, then pressurized to 0.4 MPa, and the stirring speed was adjusted to 800 rpm. The reaction was carried out at 80 °C for 60 min, and then the temperature was increased to 150 °C for 180 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the reactor pressure and remove methanol produced by ester-amine exchange. Then the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min. After that, the temperature was raised to 230℃ and held for 360 min to obtain PA4F, with Mn = 2063 g / mol, Mw = 7133 g / mol, PD = 3.46, and Tg = 125℃.

[0040] Example 8: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.23 g of [Bmim][BF4] ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times, then pressurized to 0.4 MPa, and the stirring speed was adjusted to 800 rpm. The reaction was carried out at 80 °C for 60 min, and then the temperature was increased to 150 °C for 180 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the reactor pressure and remove methanol produced by ester-amine exchange. Then the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min. After that, the temperature was raised to 230℃ and held for 360 min to obtain PA4F, with Mn = 2638 g / mol, Mw = 8620 g / mol, PD = 3.27, and Tg = 127℃.

[0041] Example 9: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.23 g of [Bmim][PF6] ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times, then pressurized to 0.4 MPa, and the stirring speed was adjusted to 800 rpm. The reaction was carried out at 80 °C for 60 min, and then the temperature was increased to 150 °C for 180 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the reactor pressure and remove methanol produced by ester-amine exchange. Then the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min. After that, the temperature was raised to 230℃ and held for 360 min to obtain PA4F, with Mn = 5197 g / mol, Mw = 21283 g / mol, PD = 4.09, and Tg = 136℃.

[0042] Example 10: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.23 g of [Bmim][CH3COO] ionic liquid, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times, then pressurized to 0.4 MPa, and the stirring speed was adjusted to 800 rpm. The reaction was carried out at 80 °C for 60 min, and then the temperature was increased to 150 °C for 180 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the reactor pressure and remove methanol produced by ester-amine exchange. Then the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min. After that, the temperature was raised to 230℃ and held for 360 min to obtain PA4F, with Mn = 2573 g / mol, Mw = 9162 g / mol, PD = 3.56, and Tg = 131℃.

[0043] Comparative Example 1: 27.62g of dimethyl furanate, 13.88g of 1,4-butanediamine, 0.2g of sodium hypophosphite, and 50.20g of deionized water were added to a 100ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly replaced with nitrogen three times, pressurized to 0.4MPa, and the stirring speed was adjusted to 800rpm. The reaction was carried out at 80℃ for 60min, then the temperature was increased to 150℃ and the reaction was carried out for 180min. After the reaction was completed, the temperature was maintained at 80℃ for 60min with mechanical stirring at 50rpm. Nitrogen was introduced to restore the pressure of the reactor and remove methanol produced by ester-amine exchange. Then the temperature was increased to 130℃ and maintained for 30min. Vacuum was drawn to gradually reduce the pressure of the reaction system to below 1000pa. At this time, the molecular weight of the polymer was further increased with the removal of by-products and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min. After that, the temperature was raised to 220℃ and held for 360 min to obtain PA4F, with Mn = 13435 g / mol, Mw = 35716 g / mol, PD = 2.66, and Tg = 136℃.

[0044] Comparative Example 2: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.2 g of isopropyl titanate, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times until the pressure reached 0.4 MPa. The stirring speed was adjusted to 800 rpm, and the reaction was carried out at 80 °C for 60 min. Then, the temperature was increased to 190 °C and the reaction was carried out for 360 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the pressure of the reactor and remove methanol produced by ester-amine exchange. Then, the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min, followed by raising the temperature to 230℃ and holding for 360 min to obtain PA4F, with Mn = 6392 g / mol, Mw = 15977 g / mol, PD = 2.50, and Tg = 121℃.

[0045] Comparative Example 3: 13.81 g of dimethyl furanate, 6.94 g of 1,4-butanediamine, 0.2 g of H3PO4, and 25 g of deionized water were added to a 100 ml high-pressure reactor equipped with a stirrer. The gas atmosphere in the system was repeatedly purged with nitrogen three times until the pressure reached 0.4 MPa. The stirring speed was adjusted to 800 rpm, and the reaction was carried out at 80 °C for 60 min. Then, the temperature was increased to 150 °C and the reaction was carried out for 180 min. After the reaction, the temperature was maintained at 80 °C for 60 min with mechanical stirring at 50 rpm. Nitrogen gas was introduced to restore the pressure of the reactor and remove methanol produced by ester-amine exchange. Then, the temperature was increased to 130 °C and maintained for 30 min. Vacuum was then applied to gradually reduce the pressure of the reaction system to below 1000 Pa. At this point, the molecular weight of the polymer was further increased with the removal of byproducts and water. The temperature was then raised to 160℃ and held for 30 min, the pressure was reduced to below 100 Pa, and then the temperature was raised to 190℃ and held for 120 min, followed by raising the temperature to 230℃ and holding for 360 min to obtain PA4F, with Mn = 15749 g / mol, Mw = 34708 g / mol, PD = 2.20, and Tg = 149℃.

[0046] The physical properties of the furanyl polyamide PA4F synthesized in Examples 1-10 and Comparative Examples 1-3 are detailed in Table 1.

[0047] Table 1. Physical properties of furanyl polyamide PA4F synthesized in Examples 1-8 and Comparative Examples 1-2

[0048]

[0049] Wherein, the melting temperature 'a' is the melting point exhibited during the first heating process of DSC due to annealing and crystallization.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing furanyl polyamide based on ionic liquid catalysis, characterized in that, Bio-based poly(dimethylfuranoylbutanediamine) is prepared by melt polycondensation of dimethyl furanoyldicarboxylate and 1,4-butanediamine using an ionic liquid as a catalyst, comprising the following steps: (1) Prepolymerization stage: Dimethyl furanate, deionized water and ionic liquid catalyst are mixed in a certain proportion and 1,4-butanediamine is added. The above solution is transferred into a high-pressure reactor, and nitrogen is repeatedly purged to replace the atmosphere in the reactor with an inert atmosphere. Then the reactor is heated and pressurized to obtain an oligomer solution. (2) Polycondensation stage: The obtained oligomer solution is vacuumed at a certain temperature to remove water and by-product methanol from the system, and then the temperature is raised to carry out melt polycondensation; The prepolymerization and polycondensation stages are divided into four phases. The first phase is pressurized prepolymerization: nitrogen is used to pressurize the mixture to 0.1–0.4 MPa, with a stirring rate of 300–800 rpm, a reaction temperature of 80–120 °C, and a reaction time of 30–150 min. The second phase is heat and pressure holding: the reaction temperature is 120–190 °C, and the reaction time is 60–300 min, yielding an oligomer solution. The third phase is dehydrated under reduced pressure: the reaction temperature is 80–160 °C, the stirring rate is 50–200 rpm, the reaction time is 60–360 min, and the vacuum degree is 1000–6000 Pa. The fourth phase is melt polycondensation: the reaction temperature is 190–260 °C, the vacuum degree is controlled within 100 Pa, the stirring rate is 50–150 rpm, and the reaction time is 120–360 min. The ionic liquid catalyst is 1-butyl-3-methylimidazolium dihydrogen phosphate [Bmim][H2PO4], 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4], 1-butyl-3-methylimidazolium chlorate [Bmim]Cl, 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF6], or 1-butyl-3-methylimidazolium acetate [Bmim][CH3COO]. The amount of catalyst used is 0.1 to 1.5 wt% of the total mass of the reactants.

2. The method for preparing furanyl polyamide based on ionic liquid catalysis according to claim 1, characterized in that, The total mass ratio of dimethyl furanate and 1,4-butanediamine to deionized water is 1:0.2 to 1.5, and the monomer molar ratio of dimethyl furanate and 1,4-butanediamine is 1:0.95 to 1.

1.

3. The method for preparing furanyl polyamide based on ionic liquid catalysis according to claim 1, characterized in that, The molecular formula of the prepared polyfuran dibutyl phthalamide is: , where n is an integer, and the number-average molecular weight of the product is 9642~27229 g / mol.

4. The method for preparing furanyl polyamide based on ionic liquid catalysis according to claim 1, characterized in that, The glass transition temperature of the polyfuran dicarboxylate is 121–151 °C.

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