A bio-based semi-crystalline co-polyamide of bifuran and its preparation, depolymerization recycling method and application

Abstract

The application discloses a kind of bio-based semi-crystalline bifuran copolyamide and its preparation, depolymerization recycling method and application, it is related to bio-based polymer material technical field.The application is based on solution polymerization method using bifuran binary acid and / or its derivative, long-chain binary acid and / or its derivative as starting material and binary amine reaction, bifuran unit rigid skeleton restricts molecular chain movement, promotes the formation of crystalline region.This synthesis strategy can obtain semi-crystalline polyamide, which shows fast crystallization in the molten state, realizes the green synthesis of high-purity difuran monomer, controllable functional modification and high-efficiency polycondensation under mild conditions, finally obtains bifuran polyamide material with excellent thermal stability and crystallization performance, breaks through the bottleneck of traditional bio-based polyamide performance limitation, and lays a solid foundation for further synthesis of bio-based polyamide suitable for high-performance application scenarios.

Description

Technical Field

[0001] This invention belongs to the field of bio-based polymer materials technology, specifically relating to a bio-based semi-crystalline tandem furan copolymer polyamide and its preparation, depolymerization and recycling methods and applications. Background Technology

[0002] In recent years, biomass platform compounds, represented by furfural and 5-hydroxymethylfurfural (HMF), have provided new pathways for the greening of polyamide monomers. In particular, furan compounds, due to their rigid aromatic ring structure similar to petroleum-based aromatic monomers, are considered ideal building blocks for constructing high-performance bio-based polyamides, and furan-based polyamides have become an important branch of bio-based polymer materials. Studies have shown that 2,5-furandicarboxylic acid (FDCA), as a bio-alternative to terephthalic acid, has been successfully used to prepare polyester materials and exhibits superior barrier properties compared to traditional PET. Using biomass platform molecules such as FDCA and furfural as raw materials, fully bio-based preparation of furan-based polyamides can be achieved. These materials retain the excellent corrosion resistance and processability of traditional petroleum-based polyamides, and due to the introduction of the furan ring, they exhibit unique advantages in heat resistance and flame retardancy, showing broad application prospects in multiple fields and receiving national policy support. Building on this, researchers have turned their attention to bisfuran structures with extended conjugated systems. Among them, bisfuran monomers (such as 2,2'-bifuran-5,5'-dicarboxylic acid, BFDCA) can significantly enhance the rigidity of the polymer backbone and the π-π stacking effect due to their unique coplanar configuration and high rotational barrier, providing new ideas for the preparation of high-performance bio-based PAs.

[0003] Despite some progress in the research of furan-based polyamides, several key challenges remain: the variety of existing furan-based monomers is insufficient, preparation processes are complex, the sources of some monomer raw materials are limited, and green and efficient synthesis processes need to be developed; side reactions such as decarboxylation and N-methylation easily occur during polymerization, affecting polymer purity and molecular weight improvement; the rigid structure of the furan ring makes it difficult to balance processability and high performance in some polyamides, crystallinity control is challenging, and domestic products lack independent intellectual property rights, with industrial scale-up technology still immature. Furthermore, traditional bio-based polyamides are mostly non-depolymerizable or difficult to depolymerize, and the closed-loop recycling system for furan-based polymers is not yet perfect, becoming another bottleneck for their sustainable development. In addition, although traditional bio-based PAs such as PA 1010 use bio-based monomers, their thermal properties still cannot meet the requirements of high-end engineering plastics. However, the bifuran unit, with its planar configuration and π-conjugated extension, can effectively improve material properties. Therefore, it is urgent to develop a method for preparing and depolymerizing semi-crystalline bio-based polyamides using bifuran monomers as raw materials, laying the foundation for the synthesis of high-performance bio-based PAs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a bio-based semi-crystalline tandem furan copolymer polyamide, which addresses the shortcomings of the prior art.

[0005] Another technical problem to be solved by the present invention is to provide a method for preparing the bio-based semi-crystalline co-furan copolymer polyamide.

[0006] Another technical problem to be solved by the present invention is to provide a method for depolymerization and recovery of the bio-based semi-crystalline co-furan copolymer polyamide.

[0007] The final technical problem to be solved by this invention is to provide the application of the aforementioned bio-based semi-crystalline tandem furan copolymer polyamide.

[0008] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0009] The first aspect of this invention provides a bio-based semi-crystalline tanfuran copolyamide, the structural formula of which is shown in Formula I:

[0010] Ⅰ

[0011] The bio-based semi-crystalline syn-furan copolymer polyamide with the structural formula shown in Formula I is a ternary random copolymer formed by the random alternation of structural units A, B, and C. Each structural unit B and each structural unit C is directly connected only to structural unit A, and each structural unit A is directly connected only to structural unit B or structural unit C.

[0012] Among them, structural units A, B, and C are respectively:

[0013]

[0014] Where m is an integer between 5 and 12; n is an integer between 3 and 10; x and y are the mole fractions of the corresponding binary structural units in the bio-based semi-crystalline tandem furan copolymer polyamide, respectively, 0.25≤x≤0.75, 0.25≤y≤0.75, x+y=1; ran represents random copolymerization.

[0015] Where x and y are the theoretical mole fractions of the corresponding structural units, and the ratio of x to y is controlled by adjusting the feed ratio of the reaction raw materials.

[0016] In some embodiments, m is 5, 8, 10, or 12.

[0017] In some embodiments, n is 3, 6, 8, or 10.

[0018] The bio-based semi-crystalline co-furan polyamide has a number-average molecular weight of 7500-20000 Da and a molecular weight distribution of 0.8-2.

[0019] In some embodiments, the bio-based semi-crystalline co-furan polyamide has a molecular weight distribution of 1 to 1.8.

[0020] The bio-based semi-crystalline syn-furan copolymer polyamide has a crystallinity of 20-45%, a 5% thermal weight loss temperature of 380-420℃, and a melting point of 170-210℃.

[0021] The second aspect of the present invention provides a method for preparing the bio-based semi-crystalline bifuran copolymer polyamide, comprising the following steps: adding bifuran dicarboxylic acid and / or its derivatives, long-chain dicarboxylic acid and / or its derivatives, diamine, acid-binding agent and catalyst to a solvent, mixing them evenly to obtain a polymerization reaction system, carrying out a polymerization reaction to obtain a polymerization reaction liquid, separating and purifying it to obtain the final product.

[0022] In some embodiments, the preparation method of the bio-based semi-crystalline bifuran copolymer polyamide includes the following steps: dissolving bifuran dicarboxylic acids and / or their derivatives, long-chain dicarboxylic acids and / or their derivatives, and diamines in solvents to prepare a first solution, a second solution, and a third solution, respectively; dissolving an acid-binding agent and a catalyst in the third solution to obtain a fourth solution; adding the first and second solutions dropwise to the fourth solution under ice bath and stirring conditions, mixing evenly to obtain a polymerization reaction system, carrying out a polymerization reaction to obtain a polymerization reaction liquid, separating and purifying it to obtain the final product.

[0023] Wherein, the bifuran dicarboxylic acid is 2,2'-bifuran-5,5'-dicarboxylic acid; the bifuran dicarboxylic acid derivative is 2,2'-bifuran-5,5'-dicarboxyl chloride; the long-chain dicarboxylic acid is at least one selected from glutaric acid, octanoic acid, sebacic acid, and dodecanoic acid; the long-chain dicarboxylic acid derivative is at least one selected from glutaryl chloride, octanoic acid chloride, sebacic acid chloride, and 1,12-diacyl chloride dodecane; the diamine is 1,5-pentanediamine, 1,8-octanediamine, 1,10-decanediamine, and 1,12-dicarboxyl chloride dodecane. At least one of aminododecane; the acid-binding agent is at least one of triethylamine, calcium hydroxide, pyridine, and potassium carbonate; the catalyst is at least one of 1,5,7-triazabicyclo[4.4.0]decen-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, and 4-dimethylaminopyridine; the solvent is at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-diethylformamide, dimethyl sulfoxide, diphenyl ether, 2-methylnaphthalene, and 1,2-dichlorobenzene.

[0024] In some embodiments, the long-chain dicarboxylic acid is octanoic acid or sebacic acid; the long-chain dicarboxylic acid derivative is octanoyl chloride or sebacyl chloride; the diamine is 1,5-pentanediamine or 1,10-decanediamine; the acid-binding agent is triethylamine; the catalyst is 4-dimethylaminopyridine; and the solvent is N,N-dimethylformamide.

[0025] The molar ratio of the total amount of the bifuran dicarboxylic acid and / or its derivatives to the long-chain dicarboxylic acid and / or its derivatives to the molar amount of the diamine is (1 ~ 1.08): (1 ~ 1.08); the molar ratio of the bifuran dicarboxylic acid and / or its derivatives to the long-chain dicarboxylic acid and / or its derivatives is (1 ~ 3): (1 ~ 3); the molar ratio of the total amount of the bifuran dicarboxylic acid and / or its derivatives to the long-chain dicarboxylic acid and / or its derivatives to the molar amount of the acid-binding agent is 1: (1 ~ 4); the amount of catalyst added is 3 ~ 15% of the total amount of the bifuran dicarboxylic acid and / or its derivatives, the long-chain dicarboxylic acid and / or its derivatives, the diamine, and the acid-binding agent; the amount of solvent used is not particularly limited, as long as the raw materials are completely dissolved.

[0026] In some embodiments, the total amount of the bifuran dicarboxylic acid and / or its derivatives and the long-chain dicarboxylic acid and / or its derivatives is in a molar ratio of 1:1 to the diamine.

[0027] In some embodiments, the molar ratio of the bifuran dicarboxylic acid and / or its derivatives to the long-chain dicarboxylic acid and / or its derivatives is 1:1, thereby controlling the theoretical molar fraction of x to be 0.5 and the theoretical molar fraction of y to be 0.5.

[0028] In some embodiments, the molar ratio of the bifuran dicarboxylic acid and / or its derivatives to the long-chain dicarboxylic acid and / or its derivatives is 1:3, thereby controlling the theoretical molar fraction of x to be 0.25 and the theoretical molar fraction of y to be 0.75.

[0029] In some embodiments, the molar ratio of the bifuran dicarboxylic acid and / or its derivatives to the long-chain dicarboxylic acid and / or its derivatives is 3:1, thereby controlling the theoretical molar fraction of x to be 0.75 and the theoretical molar fraction of y to be 0.25.

[0030] In some embodiments, the ratio of the total amount of the bifuran dicarboxylic acid and / or its derivatives to the amount of the long-chain dicarboxylic acid and / or its derivatives to the amount of the acid-binding agent is 1:3.

[0031] In some embodiments, the amount of catalyst added is 4.6% of the total amount of the bifuran dicarboxylic acid and / or its derivatives, long-chain dicarboxylic acid and / or its derivatives, diamine and acid-binding agent.

[0032] In some embodiments, the first and second solutions are added dropwise to the fourth solution at a flow rate of 0.5 to 2 mL / min.

[0033] The polymerization reaction is carried out under nitrogen atmosphere at 60-140°C with stirring for 1-6 hours.

[0034] In some embodiments, the polymerization reaction is carried out under nitrogen atmosphere at 80°C with stirring for 4 hours.

[0035] In some embodiments, the separation and purification includes the following steps: adding the polymerization reaction solution to water, precipitating a precipitate, separating the solid and liquid, washing the solid, and drying it to obtain the bio-based semi-crystalline tanfuran copolymer polyamide.

[0036] In some embodiments, adding the polymerization reaction solution to water means adding the polymerization reaction solution dropwise to water at a flow rate of 5 to 10 mL / min.

[0037] In some embodiments, the volume of water used is at least 10 times the volume of the solvent used to prepare the polymerization reaction system.

[0038] In some embodiments, the washing solid is a solid that is washed sequentially with water, dilute hydrochloric acid, and ethanol.

[0039] A third aspect of the present invention provides a method for depolymerizing and recovering the aforementioned bio-based semi-crystalline difuran copolyamide, comprising the following steps:

[0040] Step 1: Add the bio-based semi-crystalline tanfuran copolymer polyamide to an aqueous sodium hydroxide solution to carry out the first reaction, obtain the first reaction solution, extract, and collect the organic phase and aqueous phase respectively.

[0041] Step 2: Distill the organic phase obtained in Step 1 to obtain a diamine monomer; adjust the pH of the aqueous phase obtained in Step 1 to acidic, precipitate out, and obtain a mixture of 2,2'-difuran-5,5'-dicarboxylic acid and long-chain dicarboxylic acid.

[0042] The concentration of the sodium hydroxide aqueous solution is 1-6 M; the reaction conditions for the first reaction are: 140-200℃ for 4-10 h; the acidity is a pH value of 2-3.

[0043] In some embodiments, before adjusting the pH of the aqueous phase obtained in step 1 to acidic, the aqueous phase obtained in step 1 is first subjected to solid-liquid separation to remove the solid portion. The solid portion is undepolymerized bio-based semi-crystalline difuran copolymer polyamide.

[0044] In some embodiments, the liquid-to-solid ratio of the aqueous sodium hydroxide solution to the bio-based semi-crystalline cyclofuran copolymer polyacrylamide is 1 mL : 10 mg.

[0045] In some embodiments, the extractant used in the extraction is dichloromethane.

[0046] In some embodiments, the distillation is vacuum distillation, with no particular limitation on the operating parameters, aiming to remove the extractant and retain the diamine.

[0047] In some embodiments, the reagent used to adjust the pH of the aqueous phase is an aqueous solution of hydrochloric acid.

[0048] In some embodiments, the drying is vacuum drying at 60-80°C for 8-12 hours.

[0049] The fourth aspect of this invention provides the application of the aforementioned bio-based semi-crystalline co-furan polyamide in the preparation of synthetic fibers and plastic products.

[0050] This invention addresses the technical bottlenecks in monomer synthesis efficiency, functionalization design, and polymerization processes of existing bio-based polyamide materials, proposing an innovative method for the efficient preparation of bio-based semi-crystalline bifuran copolymer polyamides. Based on solution polymerization, bifuran-based diacids and / or their derivatives, long-chain diacids and / or their derivatives, are used as starting materials to react with diamines. The rigid skeleton of the bifuran units restricts molecular chain movement, promoting the formation of crystalline regions. This synthetic strategy yields semi-crystalline polyamides exhibiting rapid crystallization in the molten state, achieving green synthesis of high-purity bifuran monomers, controllable functionalization modification, and efficient polycondensation under mild conditions, ultimately obtaining bifuran polyamide materials with excellent thermal stability and crystallinity.

[0051] Beneficial effects:

[0052] (1) This invention innovatively selects a planar furan unit as the core structural unit. This planar configuration can significantly extend the π-conjugated system between the two furan rings. This structural design is different from the traditional single furan unit and significantly improves the stability and reactivity at the molecular level of furan. At the same time, with the help of the rigid skeleton of the furan unit and the synergistic effect of the amide bond, a polyamide with semi-crystalline properties is constructed. Its thermodynamic properties, mechanical properties and UV blocking properties are significantly better than those of traditional bio-based polyamides and ordinary furan-based polyamides. It can meet the performance requirements of high-end engineering materials and lay a solid foundation for the further synthesis of high-performance bio-based polyamides.

[0053] (2) The present invention uses solvent polymerization to prepare semi-crystalline furan copolymer polyamide. The target product can be obtained by simple stirring polymerization, precipitation, washing and drying. The process is simple and easy to operate, which effectively reduces the occurrence of side reactions such as decarboxylation and N-methylation during polymerization and improves the purity and molecular weight of the polymer. At the same time, the raw materials used can be prepared based on biomass platform compounds, which are renewable and have good environmental compatibility. This overcomes the problems of insufficient variety of furan polyamide monomers, complex preparation process and difficulty in industrial scale-up, which facilitates large-scale production and promotion.

[0054] (3) Realize resource recycling and conform to the concept of green and low-carbon development. The present invention designs a depolymerization process under alkaline conditions, which can efficiently recover monomers in polymers. It solves the problems of traditional bio-based polyamides being unable to depolymerize or having great difficulty in depolymerization, which easily leads to resource waste and environmental burden. It constructs a closed-loop recycling system of "monomer-polymer-monomer", reduces dependence on fossil resources, helps promote the global carbon neutrality strategy, and has both environmental protection and resource utilization efficiency.

[0055] (4) Expanding application scenarios and enhancing product competitiveness. The bio-based semi-crystalline bifuran polyamide prepared by this invention has excellent thermal stability, mechanical properties, chemical resistance, and UV barrier properties. It retains the application advantages of traditional polyamides and makes up for the shortcomings of existing bio-based polyamides. It can be widely used in high-end fields such as textiles, automobiles, electronics, and packaging. At the same time, it fills the technological gap of bifuran-type semi-crystalline bio-based polyamides and enhances the level of independent intellectual property rights and market competitiveness of bio-based polymer materials in my country. Attached Figure Description

[0056] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0057] Figure 1 The image shows the 1H NMR spectrum of the bio-based semi-crystalline tanfuran copolymer polyamide prepared in Example 1.

[0058] Figure 2 The infrared spectrum is shown for the bio-based semi-crystalline tanfuran copolymer polyamide prepared in Example 1.

[0059] Figure 3 The image shows the XRD pattern of the bio-based semi-crystalline tanfuran copolymer polyamide prepared in Example 1.

[0060] Figure 4 The TGA and DSC spectra of the bio-based semi-crystalline co-furan polyamide prepared in Example 1 are shown; wherein, figure a is the TGA spectrum and figure b is the DSC spectrum.

[0061] Figure 5The image shows the UV-Vis transmission spectrum of the bio-based semi-crystalline tanfuran copolymer polyamide prepared in Example 1.

[0062] Figure 6 The image shows the UV-Vis transmission spectrum of the bio-based semi-crystalline tanfuran copolymer polyamide prepared in Example 2. Detailed Implementation

[0063] The present invention will be further described below with reference to the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0064] For any specific techniques or conditions not specified in the examples, the techniques or conditions described in the literature in this field, or the product instructions, shall be followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0065] Example 1: Preparation of bio-based semi-crystalline syn-furan copolyamide

[0066]

[0067] Accurately weigh 0.00175 mol of 2,2'-bifuran-5,5'-dicarboxylic chloride (BFDCl), 0.00525 mol of sebacic acid chloride (DDCl), 0.007 mol of 1,10-decanediamine (DDA), 0.021 mol of triethylamine (TEA), and 0.00161 mol of 4-dimethylaminopyridine (DMAP) using a 0.00161 mol balance. Dissolve BFDCl, DDCl, and DDA separately in an appropriate amount of ultra-dry N,N-dimethylformamide (DMF) (the amount of DMF is not specifically limited; complete dissolution of BFDCl, DDCl, or DDA is sufficient) to prepare a clear solution of uniform concentration. Subsequently, add TEA and DMAP sequentially to the DDA DMF solution, stirring to dissolve and form a homogeneous and transparent DDA mixture. The DDA mixture was placed in an ice bath (0 ~ 5℃) and magnetically stirred. BFDCl DMF solution and DDCl DMF solution were then slowly added dropwise (at a flow rate of 1 mL / min) to avoid excessively vigorous local reactions. After the addition was complete, the polymerization reaction system was obtained.

[0068] The reaction system was subjected to vacuum-nitrogen purging (repeated 3 times), and then the temperature of the polymerization reaction system was raised to 80°C using a programmed temperature riser. The polymerization reaction was carried out at this temperature with magnetic stirring for 4 hours. After the polymerization reaction was completed, the reaction solution was allowed to cool naturally to room temperature, resulting in a yellow viscous reaction solution. This solution was slowly added dropwise (approximately 5 mL / min) to excess water (the amount used was 10 times the volume of DMF used to prepare the above polymerization reaction system) to induce precipitation. Solid-liquid separation was performed, and the solid fraction was collected. The solid fraction was then thoroughly washed with water, dilute hydrochloric acid, and ethanol to remove the solvent and unreacted monomers. Finally, it was vacuum dried at 60°C for 12 hours to obtain the bio-based semi-crystalline difuran copolymer polyamide of this invention, with a yield of 84%. The theoretical molar fraction ratio of x to y in the copolymer structure was x : y = 0.25 : 0.75, and the number average molecular weight (NUMBER) was... M n The value is 9237 Da, and the molecular weight distribution is 1.6.

[0069] The 1H NMR spectrum, IR spectrum, and XRD pattern of the bio-based semi-crystalline syn-furan copolymer polyamide prepared in this embodiment are shown below. Figure 1 , Figure 2 and Figure 3 As shown. Figure 1 The 1H NMR spectrum shows characteristic signals at δ=7.6 ppm (a) and 7.0 ppm (b) attributed to protons in the furan ring. Peaks at δ=3.7 ppm (c) and (f) correspond to methylene protons adjacent to -CONH-, respectively. Furthermore, peaks at δ=2.8 ppm (g), δ=1.5 ppm (h), δ=1.8 ppm (d), and δ=1.4 ppm (e) are signals attributed to methylene protons in the alkyl chain. Figure 2 The infrared spectrum shows that at 3290 cm⁻¹ -1 The absorption peak at 1576 cm⁻¹ belongs to the NH group that forms a hydrogen bond, indicating that the amide group has been successfully formed. -1 1173 cm -1 1013 cm -1 804 cm -1 811 cm -1 Each group belongs to a different group on the furan ring, 2920 cm -1 2852 cm -1 1448 cm -1 The peak represents the stretching vibration of the CH group. Figure 3 The XRD patterns show that in 2 θThree characteristic diffraction peaks appeared at 8.07°, 19.96° and 23.52°, corresponding to the (002), (100) and (010 / 110) crystal planes of the monoclinic α crystal form, respectively. The crystallinity (Xc) was calculated based on the ratio of the crystal peak area to the total area of ​​the crystalline and amorphous regions. The crystallinity of the bio-based semi-crystalline tanfuran copolymer polyamide prepared in this embodiment was calculated to be 42.17%.

[0070] Thermodynamic tests were performed on the bio-based semi-crystalline syn-furan copolymer polyamide prepared in this embodiment. The experimental results are as follows: Figure 4 The results showed that T d5% (5% thermogravimetric temperature) is 394.09℃. Figure 4 a), T m The melting point is 187.07℃. Figure 4 b).

[0071] The solid-state ultraviolet transmittance of the bio-based semi-crystalline tanfuran copolyamide prepared in this embodiment was tested, and the results are as follows: Figure 5 As shown, this indicates that it has ultraviolet blocking capabilities.

[0072] Example 2 Preparation of bio-based semi-crystalline syn-furan copolyamide

[0073]

[0074] Accurately weigh 0.00175 mol of 2,2'-bifuran-5,5'-dicarboxylic chloride (BFDCl), 0.00525 mol of sebacic acid chloride (DDCl), 0.007 mol of 1,5-pentanediamine (PDA), 0.021 mol of triethylamine (TEA), and 0.00161 mol of 4-dimethylaminopyridine (DMAP) using a 0.00161 mol balance. Dissolve BFDCl, DDCl, and PDA separately in an appropriate amount of ultra-dry N,N-dimethylformamide (DMF) (the amount of DMF is not specifically limited; it is sufficient to completely dissolve BFDCl, DDCl, or PDA) to prepare a clear solution of uniform concentration. Subsequently, add TEA and DMAP sequentially to the PDA DMF solution, stirring to dissolve and form a homogeneous and transparent PDA mixture. The PDA mixture was placed in an ice bath (0 ~ 5℃) and magnetically stirred. BFDCl DMF solution and DDCl DMF solution were then slowly added dropwise (at a flow rate of 1 mL / min) to avoid excessively vigorous local reactions. After the addition was complete, the polymerization reaction system was obtained.

[0075] The reaction system was subjected to vacuum-nitrogen purging (repeated 3 times), and then the temperature of the polymerization reaction system was raised to 80°C using a programmed temperature riser. The polymerization reaction was carried out at this temperature with magnetic stirring for 4 hours. After the polymerization reaction was completed, the reaction solution was allowed to cool naturally to room temperature, resulting in a yellow viscous reaction solution. This solution was slowly added dropwise (approximately 5 mL / min) to excess water (the amount used was 10 times the volume of DMF used to prepare the above polymerization reaction system) to induce precipitation. Solid-liquid separation was performed, and the solid fraction was collected. The solid fraction was then thoroughly washed with water, dilute hydrochloric acid, and ethanol to remove the solvent and unreacted monomers. Finally, it was vacuum dried at 60°C for 12 hours to obtain the bio-based semi-crystalline difuran copolymer polyamide of this invention, with a yield of 79%. The theoretical molar fraction ratio of x to y in the copolymer structure was x : y = 0.25 : 0.75, and the number average molecular weight (NUMBER) was... M n The molecular weight is 9166 Da, the molecular weight distribution is 1.6, the crystallinity is 36.49%, and the T... d5% The temperature was 397.61℃, T m It is 188.82℃.

[0076] The solid-state ultraviolet transmittance of the bio-based semi-crystalline tanfuran copolyamide prepared in this embodiment was tested, and the results are as follows: Figure 6 As shown, this indicates that it has ultraviolet blocking capabilities.

[0077] Example 3 Preparation of bio-based semi-crystalline syn-furan copolyamide

[0078]

[0079] Accurately weigh 0.00175 mol of 2,2'-bifuran-5,5'-dicarboxylic acid (BFDCA), 0.00525 mol of sebacic acid (DDCA), 0.007 mol of 1,10-decanediamine (DDA), 0.021 mol of triethylamine (TEA), and 0.00161 mol of 4-dimethylaminopyridine (DMAP) using a 0.00175 mol balance. Dissolve BFDCA, DDCA, and DDA separately in an appropriate amount of ultra-dry N,N-dimethylformamide (DMF) (the amount of DMF is not specifically limited; complete dissolution of BFDCA, DDCA, and DDA is sufficient) to prepare a clear solution of uniform concentration. Then, add TEA and DMAP sequentially to the DDA DMF solution, stirring to dissolve and form a homogeneous and transparent DDA mixture. The DDA mixture was placed in an ice bath (0 ~ 5℃) and magnetically stirred. BFDCA DMF solution and DDCA DMF solution were then slowly added dropwise (at a flow rate of 1 mL / min) to avoid excessively vigorous local reactions. After the addition was complete, the polymerization reaction system was obtained.

[0080] The reaction system was subjected to vacuum-nitrogen purging (repeated 3 times), and then the temperature of the polymerization reaction system was raised to 80°C using a programmed temperature riser. The polymerization reaction was carried out at this temperature with magnetic stirring for 4 hours. After the polymerization reaction was completed, the reaction solution was allowed to cool naturally to room temperature, resulting in a yellow viscous reaction solution. This solution was slowly added dropwise (approximately 5 mL / min) to excess water (the amount used was 10 times the volume of DMF used to prepare the above polymerization reaction system) to induce precipitation. Solid-liquid separation was performed, and the solid fraction was collected. The solid fraction was then thoroughly washed with water, dilute hydrochloric acid, and ethanol to remove the solvent and unreacted monomers. Finally, it was vacuum dried at 60°C for 12 hours to obtain the bio-based semi-crystalline difuran copolymer polyamide of this invention, with a yield of 79%. The theoretical molar fraction ratio of x to y in the copolymer structure was x : y = 0.25 : 0.75, and the number average molecular weight (NUMBER) was... M n The molecular weight is 8724 Da, the molecular weight distribution is 1.8, the crystallinity is 40.14%, and the T... d5% The temperature was 392.94℃, T m It is 182.70℃.

[0081] Example 4 Preparation of bio-based semi-crystalline syn-furan copolyamide

[0082]

[0083] Accurately weigh 0.00175 mol of 2,2'-bifuran-5,5'-dicarboxylic chloride (BFDCl), 0.00525 mol of sebacic acid chloride (DDCl), 0.007 mol of 1,8-octanediamine (OMDA), 0.021 mol of triethylamine (TEA), and 0.00161 mol of 4-dimethylaminopyridine (DMAP) using a 0.00161 mol balance. Dissolve BFDCl, DDCl, and OMDA separately in an appropriate amount of ultra-dry N,N-dimethylformamide (DMF) (the amount of DMF is not specifically limited; it is sufficient to completely dissolve BFDCl, DDCl, or OMDA) to prepare a clear solution of uniform concentration. Then, add TEA and DMAP sequentially to the DMF solution of OMDA, stirring to dissolve and form a uniform and transparent OMDA mixture. The OMDA mixture was placed in an ice bath (0 ~ 5℃) and magnetically stirred. BFDCl DMF solution and DDCl DMF solution were then slowly added dropwise (at a flow rate of 1 mL / min) to avoid excessively vigorous local reactions. After the addition was complete, the polymerization reaction system was obtained.

[0084] The reaction system was subjected to vacuum-nitrogen purging (repeated 3 times), and then the temperature of the reaction system was raised to 80°C using a programmed temperature riser. At this temperature, the polymerization reaction was carried out under constant temperature magnetic stirring for 4 h. After the polymerization reaction was completed, the reaction solution was allowed to cool naturally to room temperature, resulting in a yellow viscous reaction solution. This solution was slowly added dropwise (approximately 5 mL / min) to excess water (the amount used was 10 times the volume of DMF used to prepare the above polymerization reaction system) to induce precipitation. Solid-liquid separation was performed, and the solid fraction was collected. The solid fraction was then thoroughly washed with water, dilute hydrochloric acid, and ethanol to remove the solvent and unreacted monomers. Finally, it was vacuum dried at 60°C for 12 h to obtain the bio-based semi-crystalline difuran copolymer polyamide of this invention, with a yield of 79%. The theoretical molar fraction ratio of x to y in the copolymer structure was x : y = 0.25 : 0.75, and the number average molecular weight (NUMBER) was... M n The molecular weight is 9698 Da, the molecular weight distribution is 1.6, the crystallinity is 38.19%, and the T... d5% The temperature was 390.07℃, T m It is 186.73℃.

[0085] Example 5 Preparation of bio-based semi-crystalline syn-furan copolyamide

[0086]

[0087] Accurately weigh 0.00525 mol 2,2'-bifuran-5,5'-dicarboxyl chloride (BFDCl), 0.00175 mol sebacatel chloride (DDCl), 0.007 mol 1,10-decanediamine (DDA), 0.021 mol triethylamine (TEA), and 0.00161 mol 4-dimethylaminopyridine (DMAP) using a 0.00161 mol balance. Dissolve BFDCl, DDCl, and PDA separately in an appropriate amount of ultra-dry N,N-dimethylformamide (DMF) (the amount of DMF is not specifically limited; it is sufficient to completely dissolve BFDCl, DDCl, or PDA) to prepare a clear solution of uniform concentration. Subsequently, add TEA and DMAP sequentially to the DDA DMF solution, stirring to dissolve and form a homogeneous and transparent DDA mixture. The DDA mixture was placed in an ice bath (0 ~ 5℃) and magnetically stirred. BFDCl DMF solution and DDCl DMF solution were then slowly added dropwise (at a flow rate of 1 mL / min) to avoid excessively vigorous local reactions. After the addition was complete, the polymerization reaction system was obtained.

[0088] The reaction system was subjected to vacuum-nitrogen purging (repeated 3 times), and then the temperature of the polymerization reaction system was raised to 80°C using a programmed temperature riser. The polymerization reaction was carried out at this temperature with magnetic stirring for 4 hours. After the polymerization reaction was completed, the reaction solution was allowed to cool naturally to room temperature, resulting in a yellow viscous reaction solution. This solution was slowly added dropwise (approximately 5 mL / min) to excess water (the amount used was 10 times the volume of DMF used to prepare the above polymerization reaction system) to induce precipitation. Solid-liquid separation was performed, and the solid fraction was collected. The solid fraction was then thoroughly washed with water, dilute hydrochloric acid, and ethanol to remove the solvent and unreacted monomers. Finally, it was vacuum dried at 60°C for 12 hours to obtain the bio-based semi-crystalline difuran copolymer polyamide of this invention, with a yield of 81%. The theoretical molar fraction ratio of x to y in the copolymer structure was x : y = 0.75 : 0.25, and the number average molecular weight (NUMBER) was [not specified in the original text]. M n The molecular weight is 8994 Da, the molecular weight distribution is 1.3, the crystallinity is 21.77%, and the T... d5% The temperature was 401.43℃, T m It is 172.81℃.

[0089] Example 6 Preparation of bio-based semi-crystalline syn-furan copolyamide

[0090]

[0091] Accurately weigh 0.0035 mol of 2,2'-bifuran-5,5'-dicarboxylic chloride (BFDCl), 0.0035 mol of sebacic acid chloride (DDCl), 0.007 mol of 1,10-decanediamine (DDA), 0.021 mol of triethylamine (TEA), and 0.00161 mol of 4-dimethylaminopyridine (DMAP) using a 0.00161 mol balance. Dissolve BFDCl, DDCl, and PDA separately in an appropriate amount of ultra-dry N,N-dimethylformamide (DMF) (the amount of DMF is not specifically limited; it is sufficient to completely dissolve BFDCl, DDCl, or PDA) to prepare a clear solution of uniform concentration. Subsequently, add TEA and DMAP sequentially to the DDA DMF solution, stirring to dissolve and form a homogeneous and transparent DDA mixture. The DDA mixture was placed in an ice bath (0 ~ 5℃) and magnetically stirred. BFDCl DMF solution and DDCl DMF solution were then slowly added dropwise (at a flow rate of 1 mL / min) to avoid excessively vigorous local reactions. After the addition was complete, the polymerization reaction system was obtained.

[0092] The reaction system was subjected to vacuum-nitrogen purging (repeated 3 times), and then the temperature of the polymerization reaction system was raised to 80°C using a programmed temperature riser. The polymerization reaction was carried out at this temperature with magnetic stirring for 4 hours. After the polymerization reaction was completed, the reaction solution was allowed to cool naturally to room temperature, resulting in a yellow viscous reaction solution. This solution was slowly added dropwise (approximately 5 mL / min) to excess water (the amount used was 10 times the volume of DMF used to prepare the above polymerization reaction system) to induce precipitation. Solid-liquid separation was performed, and the solid fraction was collected. The solid fraction was then thoroughly washed with water, dilute hydrochloric acid, and ethanol to remove the solvent and unreacted monomers. Finally, it was vacuum dried at 60°C for 12 hours to obtain the bio-based semi-crystalline difuran copolymer polyamide of this invention, with a yield of 76%. The theoretical molar fraction ratio of x to y in the copolymer structure is x:y = 0.5:0.5, and the number average molecular weight (NUMBER) is... M n The molecular weight is 8493 Da, the molecular weight distribution is 1.7, the crystallinity is 27.86%, and the T... d5% The temperature was 392.67℃, T m It is 177.09℃.

[0093] Example 7 Preparation of bio-based semi-crystalline syn-furan copolyamide

[0094]

[0095] Accurately weigh 0.00175 mol of 2,2'-bifuran-5,5'-dicarboxyl chloride (BFDCl), 0.00525 mol of octanoyl chloride (OMDl), 0.007 mol of 1,10-decanediamine (DDA), 0.021 mol of triethylamine (TEA), and 0.00161 mol of 4-dimethylaminopyridine (DMAP) using a 0.00161 mol balance. Dissolve BFDCl, OMDl, and DDA separately in an appropriate amount of ultra-dry N,N-dimethylformamide (DMF) (the amount of DMF is not specifically limited; it is sufficient to completely dissolve BFDCl, OMDl, and DDA) to prepare a clear solution of uniform concentration. Subsequently, add TEA and DMAP sequentially to the DDA DMF solution, stirring to dissolve and form a homogeneous and transparent DDA mixture. The DDA mixture was placed in an ice bath (0 ~ 5℃) and magnetically stirred. BFDCl DMF solution and OMDl DMF solution were then slowly added dropwise (at a flow rate of 1 mL / min) to avoid excessively vigorous local reactions. After the addition was complete, the polymerization reaction system was obtained.

[0096] The reaction system was subjected to vacuum-nitrogen purging (repeated 3 times), and then the temperature of the polymerization reaction system was raised to 80°C using a programmed temperature riser. The polymerization reaction was carried out at this temperature with magnetic stirring for 4 hours. After the polymerization reaction was completed, the reaction solution was allowed to cool naturally to room temperature, resulting in a yellow viscous reaction solution. This solution was slowly added dropwise (approximately 5 mL / min) to excess water (the amount used was 10 times the volume of DMF used to prepare the above polymerization reaction system) to induce precipitation. Solid-liquid separation was performed, and the solid fraction was collected. The solid fraction was then thoroughly washed with water, dilute hydrochloric acid, and ethanol to remove the solvent and unreacted monomers. Finally, it was vacuum dried at 60°C for 12 hours to obtain the bio-based semi-crystalline difuran copolymer polyamide of this invention, with a yield of 79%. The theoretical molar fraction ratio of x to y in the copolymer structure was x : y = 0.25 : 0.75, and the number average molecular weight (NUMBER) was... M n The molecular weight is 8205 Da, the molecular weight distribution is 1.5, the crystallinity is 37.22%, and the T... d5% The temperature was 389.71℃, T m It is 177.24℃.

[0097] Example 8 Depolymerization and recovery of bio-based semi-crystalline difuran copolyamide

[0098] Weigh 50 mg of the bio-based semi-crystalline cyclofuran copolymer polyamide prepared in Example 1 into a pressure-resistant tube, add 5 mL of 6 M NaOH aqueous solution, and react at 200 °C for 10 h. After the reaction is completed and the reaction solution is cooled to room temperature, extract with dichloromethane since the 1,10-decanediamine suspension is on the liquid surface, and collect the organic phase and the aqueous phase.

[0099] Dichloromethane was removed from the organic phase by vacuum distillation to obtain 1,10-decanediamine monomer with a recovery rate of 74%. The aqueous phase was filtered to obtain a solid (undepolymerized polyamide) and a filtrate. The pH of the filtrate was adjusted to 2-3 with hydrochloric acid solution. The resulting precipitate was a mixture of 2,2'-difuran-5,5'-dicarboxylic acid and sebacic acid, which was collected by filtration and dried under vacuum to constant weight. The recovery rate of the mixture of 2,2'-difuran-5,5'-dicarboxylic acid and sebacic acid was 69%.

[0100] The recovery rate is calculated as follows: Recovery rate = (Actual recovery amount / Theoretical recovery amount) × 100%.

[0101] Comparative Example 1: Preparation of Bio-based Furan Polyamide

[0102] 0.007 mol 2,5-furandicarboxylic acid chloride (FDCl), 0.007 mol 1,10-decanediamine (DDA), 0.0021 mol triethylamine (TEA), and 0.00161 mol 4-dimethylaminopyridine (DMAP) were accurately weighed using a 0.001500 ppm balance. FDCl and DDA were dissolved separately in an appropriate amount of ultra-dry N,N-dimethylformamide (DMF) (the amount of DMF used is not specifically limited; complete dissolution of FDCl or DDA is sufficient) to prepare a clear solution of uniform concentration. Subsequently, TEA and DMAP were added sequentially to the DDA DMF solution, and the mixture was stirred to dissolve, forming a homogeneous and transparent DDA mixture. The DDA mixture was placed in an ice bath (0–5°C) and magnetically stirred. The FDCl DMF solution was slowly added dropwise (at a flow rate of 1 mL / min) to avoid excessively vigorous localized reactions. After the addition was complete, the polymerization reaction system was obtained.

[0103] The reaction system was subjected to vacuum-nitrogen purging (repeated 3 times), and then the polymerization temperature was raised to 80°C using a programmed temperature riser. The polymerization reaction was carried out at this temperature with magnetic stirring for 4 h. After the polymerization reaction, the reaction solution was allowed to cool naturally to room temperature, resulting in a yellow viscous reaction solution. This solution was slowly added dropwise (approximately 5 mL / min) to excess water to precipitate the solid. Solid-liquid separation was performed, and the solid fraction was collected. The solid fraction was then thoroughly washed with water, dilute hydrochloric acid, and ethanol to remove the solvent and unreacted monomers. Finally, it was vacuum dried at 60°C for 12 h to obtain the bio-based furan polyamide, with a yield of 74% and a crystallinity of 0%. d5% It has a temperature of 405.23 ℃ and no obvious melting point.

[0104] Comparative Example 2: Preparation of Bio-based Semi-crystalline Furan Polyamide

[0105] 0.007 mol of 2,2'-bifuran-5,5'-dicarboxylic chloride (BFDCl), 0.007 mol of 1,10-decanediamine (DDA), 0.0021 mol of triethylamine (TEA), and 0.00161 mol of 4-dimethylaminopyridine (DMAP) were accurately weighed using a 0.001 balance. BFDCl and DDA were dissolved separately in an appropriate amount of ultra-dry N,N-dimethylformamide (DMF) (the amount of DMF used is not specifically limited; complete dissolution of BFDCl or DDA is sufficient) to prepare a clear solution of uniform concentration. Subsequently, TEA and DMAP were added sequentially to the DDA DMF solution, and the mixture was stirred to dissolve, forming a homogeneous and transparent DDA mixture. The DDA mixture was placed in an ice bath (0 ~ 5℃) and magnetically stirred. The BFDCl DMF solution was slowly added dropwise (at a flow rate of 1 mL / min) to avoid excessively vigorous localized reactions. After the addition was complete, the polymerization reaction system was obtained.

[0106] The reaction system was subjected to vacuum-nitrogen purging (repeated 3 times), and then the temperature of the polymerization reaction system was raised to 80°C using a programmed temperature riser. The polymerization reaction was carried out at this temperature with magnetic stirring for 4 h. After the polymerization reaction was completed, the reaction solution was allowed to cool naturally to room temperature, resulting in a yellow viscous reaction solution. This solution was slowly added dropwise (approximately 5 mL / min) to excess water to precipitate the solid. Solid-liquid separation was performed, and the solid fraction was collected. The solid fraction was then thoroughly washed with water, dilute hydrochloric acid, and ethanol to remove the solvent and unreacted monomers. Finally, it was vacuum dried at 60°C for 12 h to obtain the bio-based semi-crystalline syn-furan copolymer polyamide of this invention, with a yield of 88% and a crystallinity of 39.82%. d5% The temperature was 417.75℃.

[0107] This invention provides a concept and method for the preparation, depolymerization and recovery of a bio-based semi-crystalline co-furan polyamide and its applications. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A bio-based semi-crystalline co-furan polyamide, characterized in that, Its structural formula is shown in Formula I: Ⅰ Where m is an integer between 5 and 12; n is an integer between 3 and 10; x and y are the mole fractions of the corresponding structural units, 0.25≤x≤0.75, 0.25≤y≤0.75, x + y = 1; ran represents random copolymerization; The bio-based semi-crystalline co-furan polyamide has a number-average molecular weight of 7500-20000 Da and a molecular weight distribution of 0.8-2.

2. The bio-based semi-crystalline syn-furan copolyamide according to claim 1, characterized in that, Its crystallinity is 20-45%, its 5% thermal weight loss temperature is 380-420℃, and its melting point is 170-210℃.

3. The method for preparing the bio-based semi-crystalline syn-furan copolyamide according to claim 1 or 2, characterized in that, The process includes the following steps: adding bifuran dicarboxylic acid and / or its derivatives, long-chain dicarboxylic acid and / or its derivatives, diamine, acid-binding agent and catalyst to a solvent, mixing them evenly to obtain a polymerization reaction system, carrying out the polymerization reaction to obtain a polymerization reaction liquid, separating and purifying it to obtain the final product.

4. The preparation method according to claim 3, characterized in that, The bifuran dicarboxylic acid is 2,2'-bifuran-5,5'-dicarboxylic acid; the bifuran dicarboxylic acid derivative is 2,2'-bifuran-5,5'-dicarboxyl chloride; the long-chain dicarboxylic acid is at least one selected from glutaric acid, octanoic acid, sebacic acid, and dodecanoic acid; the long-chain dicarboxylic acid derivative is at least one selected from glutaryl chloride, octanoyl chloride, sebacyl chloride, and 1,12-diacyl chloride dodecane; the diamine is 1,5-pentanediamine, 1,8-octanediamine, 1,10-decanediamine, and 1,12-diamine. The solvent is at least one of the following: 1,5,7-triazabicyclo[4.4.0]decen-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, and 4-dimethylaminopyridine; the solvent is at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-diethylformamide, dimethyl sulfoxide, diphenyl ether, 2-methylnaphthalene, and 1,2-dichlorobenzene.

5. The preparation method according to claim 3, characterized in that, The molar ratio of the total amount of the bifuran dicarboxylic acid and / or its derivatives to the long-chain dicarboxylic acid and / or its derivatives to the molar ratio of the diamine is (1 ~ 1.08): (1 ~ 1.08); the molar ratio of the bifuran dicarboxylic acid and / or its derivatives to the long-chain dicarboxylic acid and / or its derivatives is (1 ~ 3): (1 ~ 3); the molar ratio of the total amount of the bifuran dicarboxylic acid and / or its derivatives to the long-chain dicarboxylic acid and / or its derivatives to the molar ratio of the acid-binding agent is 1: (1 ~ 4); the amount of catalyst added is 3 ~ 15% of the total amount of the bifuran dicarboxylic acid and / or its derivatives, the long-chain dicarboxylic acid and / or its derivatives, the diamine, and the acid-binding agent.

6. The preparation method according to claim 3, characterized in that, The polymerization reaction is carried out under nitrogen atmosphere at 60-140°C with stirring for 1-6 hours.

7. The preparation method according to claim 3, characterized in that, The separation and purification process includes the following steps: adding the polymerization reaction solution to water, precipitating a solid, separating the solid and liquid, washing the solid, and drying it to obtain the bio-based semi-crystalline tanfuran copolymer polyamide.

8. The method for depolymerization and recovery of the bio-based semi-crystalline difuran copolyamide according to claim 1 or 2, characterized in that, Includes the following steps: Step 1: Add the bio-based semi-crystalline tanfuran copolymer polyamide to an aqueous sodium hydroxide solution to carry out the first reaction, obtain the first reaction solution, extract, and collect the organic phase and aqueous phase respectively; Step 2: Distill the organic phase obtained in Step 1 to obtain a diamine monomer; adjust the pH of the aqueous phase obtained in Step 1 to acidic, precipitate out, and obtain a mixture of 2,2'-difuran-5,5'-dicarboxylic acid and long-chain dicarboxylic acid.

9. The depolymerization and recycling method according to claim 8, characterized in that, The concentration of the sodium hydroxide aqueous solution is 1~6 M; the reaction conditions for the first reaction are: 140~200℃ for 4~10 h; the acidity is pH 2~3.

10. The use of the bio-based semi-crystalline co-furan copolymer polyamide according to claim 1 or 2 in the preparation of synthetic fibers and plastic products.

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