Closed-loop recyclable bio-based resin as well as preparation method and application thereof

Abstract

The invention discloses bio-based resin capable of being recycled in a closed-loop mode and a preparation method and application of the bio-based resin. According to the resin material, bio-based polybasic acid serves as a raw material and is mixed with 4-carboxyphenylboronic acid, then the mixture and ethylene glycol diglycidyl ether are subjected to an epoxy ring-opening reaction to prepare a bio-based monomer with the end group being boric acid, and the resin is prepared after the monomer is subjected to cross-linking polymerization. Wherein the bio-based polybasic acid is azelaic acid, sebacic acid, Brazil acid, acrylic abietic acid, eleostearic acid anhydride, maleated rosin and the like. The end group of the bio-based monomer is boric acid bonds, and small molecule amine is subjected to catalytic dehydration to form dynamic boric acid ester, so that the monomer is cross-linked to prepare a material with closed-loop recovery, shape memory and self-repairing performance, and the material has wide application prospects in the fields of 3D printing, flexible sensors and friction generator materials.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis technology, specifically relating to a bio-based resin that can be recycled in a closed loop, its preparation method, and its application. Background Technology

[0002] The rise of closed-loop recyclable materials technology is rooted in a profound global reflection on the resource crisis and environmental pollution caused by the linear economy's "get-manufacture-dispose" model. Traditional materials, especially composite materials and plastic products, are often downgraded for recycling or directly landfilled and incinerated after use, leading to resource waste and ecological burden. To overcome this dilemma, it is necessary to design products that are renewable from the source and can efficiently return to the production system after their lifespan, thereby achieving resource recycling and reducing dependence on non-renewable resources and environmental impact.

[0003] Achieving closed-loop recycling requires breakthroughs in both materials science and manufacturing processes. At the materials level, research focuses on single-material design, easily depolymerizable polymer structures (such as depolymerizable plastics), and bio-based biodegradable materials to ensure the integrity of the material's chemical structure and properties during recycling. At the process level, this involves reprocessing technologies, efficient and precise chemical recycling methods (such as depolymerization and pyrolysis to reduce waste to monomers), and physical recycling. These technological advancements collectively form the material basis for closed-loop material regeneration, making "waste-to-raw material" both technically and economically possible.

[0004] Borate ester bonds are dynamic covalent bonds whose unique reversible properties (the ability to break and reform under specific conditions, such as moisture, heat, or acid stimulation) make them ideal for designing recyclable, remodelable, and self-healing materials. In recent years, significant progress has been made in developing closed-loop recyclable polymers using this functional group. Zhang et al. reported a glass polymer based on borate ester bonds. This material exhibits the mechanical strength, stability, and solvent resistance of conventional thermosetting plastics at room temperature, making it suitable for load-bearing structures. Its core innovation lies in the dramatic acceleration of the borate ester bond exchange reaction rate when heated to specific temperatures (e.g., above 100°C), resulting in a glass-like fluidity that allows for reshaping, welding, or repair without degradation. More importantly, when placed in specific acidic aqueous solutions, the borate ester bonds can be selectively hydrolyzed, breaking down the polymer network into original monomers. These monomers can be easily separated and purified, and then used to resynthesize new materials with the exact same properties, achieving true closed-loop monomer recycling. Liu et al. reported a class of studies that combines borate ester bonds with other dynamic bonds (such as Schiff bases and imine bonds) using bio-based raw materials. This work synthesized a dual-dynamic network thermosetting resin containing dynamic borate ester bonds and imine bonds, using vanillin derived from lignin as the main raw material. This material not only possesses good mechanical properties and thermal stability but also offers a triple recycling pathway: physical reprocessing, chemical degradation, and closed-loop recycling. Summary of the Invention

[0005] Technical problem to be solved: This invention provides a bio-based resin that can be recycled in a closed loop, its preparation method and application. The material has excellent monomer recycling performance, shape memory performance and self-healing performance.

[0006] Technical solution: A bio-based resin that can be recycled in a closed loop, with the chemical structure shown below:

[0007]

[0008] Where R is any one of the following groups:

[0009]

[0010] .

[0011] The above-mentioned method for preparing the closed-loop recyclable bio-based resin involves dissolving a bio-based polyacid in mixture with 4-carboxyphenylboronic acid, followed by a ring-opening addition reaction with ethylene glycol diglycidyl ether to synthesize a bio-based monomer with boric acid as the terminal group. The chemical structural formula is shown below:

[0012]

[0013] Where R is any one of the following groups:

[0014]

[0015] ;

[0016] Using a small molecule amine as a catalyst, it is dissolved with a bio-based monomer with boric acid at the end in a mixed solvent of THF and DMF, then heated for dehydration polymerization, and the solvent is removed to obtain a bio-based resin that can be closed-loop recycled.

[0017] The aforementioned bio-based polyacids are one of azelaic acid, sebacic acid, brassic acid, acrylonitrile acid, tung oil anhydride, and maleic rosin.

[0018] The molar ratio of the above-mentioned bio-based polyacid, 4-carboxyphenylboronic acid and ethylene glycol diglycidyl ether is 1:n:n, where n is the number of carboxylic acids in the bio-based polyacid.

[0019] The solvent used in the above ring-opening addition reaction is a mixture of water and DMF in a volume ratio of 1:2 to 1:6, the temperature is 90 to 130°C, and the reaction time is 6 to 24 hours.

[0020] The aforementioned small molecule amine is one of diethanolamine (DEA), triethanolamine (TEA), serine, and N-methyl-2-pyrrolidone (NMP), and the molar ratio of the bio-based monomer with boric acid end group to the amine bond is 1:1 to 1:12.

[0021] The organic solvent used in the above dehydration polymerization reaction is a mixture of THF and DMF in a volume ratio of 1:1 to 1:12. The oven temperature is 120-160 ℃ and the dehydration time is 24-48 h.

[0022] The aforementioned bio-based resins that can be recycled in a closed loop can be used in the preparation of 3D printing inks, flexible sensors, and triboelectric generator materials.

[0023] Beneficial Effects: This invention synthesizes bio-based monomers with boric acid as the end group from bio-based polyacids, and synthesizes a bio-based resin based on dynamic borate ester bonds through an amine-catalyzed dehydration reaction of boric acid. This bio-based resin material possesses excellent monomer recovery performance, shape memory properties, and self-healing properties. It can achieve spontaneous detection and repair of material damage, thereby preventing potential destruction due to microscopic damage and extending the service life of products. Furthermore, the resulting products can be efficiently returned to the production system after the end of their service life, thus achieving resource recycling, reducing dependence on non-renewable resources and environmental impact, and showing broad application prospects in the fields of 3D printing, flexible sensors, and triboelectric generator materials. Attached Figure Description

[0024] Figure 1 Hydrogen NMR spectrum of tungmaic anhydride.

[0025] Figure 2 Hydrogen NMR spectrum of Malaysian rosin.

[0026] Figure 3 1H NMR spectrum of tung oil-based monomers with boric acid end groups.

[0027] Figure 4 The 1H NMR spectrum of maleic rosin monomer with boric acid as the terminal group.

[0028] Figure 5 Mechanical properties of bio-based resins that can be recycled in a closed loop.

[0029] Figure 6 Closed-loop recycling of bio-based resins.

[0030] Figure 7 Shape memory of bio-based resins that can be recycled in a closed loop.

[0031] Figure 8 Self-healing properties of bio-based resins that can be recycled in a closed loop. Detailed Implementation

[0032] Example 1

[0033] 4g of tung oil anhydride and 5.4g of 4-carboxyphenylboronic acid were dissolved in a mixed solvent of water and DMF (volume ratio 1:3), and then 5.6g of ethylene glycol diglycidyl ether was added. The mixture was reacted at 120℃ for 12h to synthesize a tung oil-based monomer with boric acid at the end group. 2g of the tung oil-based monomer with boric acid at the end group was dissolved in 6 mL of a mixed solution containing 0.02g of serine and 0.015g of terephthalaldehyde (DMF:THF volume ratio = 1:2). The mixture was stirred at 25℃ for 30 minutes, and then the reaction mixture was poured into a specially made polytetrafluoroethylene mold and placed in a drying oven at 140℃ for 24h. After evaporating the solvent, a bio-based resin with closed-loop recovery was obtained. 0.2g of the prepared bio-based resin with closed-loop recovery was hydrolyzed in 1.5ml of ammonia:water (1:1 ratio) for 24h to recover the tung oil-based monomer with boric acid at the end group, with a monomer recovery rate of 83.7%.

[0034] Example 2

[0035] 4g of maleic rosin and 5g of 4-carboxyphenylboronic acid were dissolved in a mixed solvent of water and DMF (volume ratio 1:3), and then 5.2g of ethylene glycol diglycidyl ether was added. The mixture was reacted at 120℃ for 12h to synthesize a rosin monomer with boric acid at the end group. 2g of the rosin monomer with boric acid at the end group was dissolved in 6 mL of a mixed solution containing 0.02g of serine and 0.015g of terephthalaldehyde (DMF:THF volume ratio = 1:2). The mixture was stirred at 25℃ for 30 minutes, and then the reaction mixture was poured into a specially made polytetrafluoroethylene mold and placed in a drying oven at 140℃ for 24h. After evaporating the solvent, a bio-based resin with closed-loop recovery was obtained. 0.2g of the prepared bio-based resin with closed-loop recovery was hydrolyzed in 1.5ml of ammonia:water (1:1 ratio) for 24h to recover the rosin monomer with boric acid at the end group, with a monomer recovery rate of 84.2%.

[0036] Example 3

[0037] 1 g of the tung oil-based monomer with boric acid terminal group prepared in Example 1 and 1 g of the rosin-based monomer with boric acid terminal group prepared in Example 2 were dissolved in 6 mL of a mixed solution containing 0.02 g serineol and 0.015 g terephthalaldehyde (DMF:THF volume ratio = 1:2). After stirring at 25°C for 30 minutes, the reaction mixture was poured into a specially made polytetrafluoroethylene mold and placed in a drying oven at 140°C for 24 hours. After evaporating the solvent, a bio-based resin with closed-loop recovery was obtained. 0.2 g of the prepared bio-based resin with closed-loop recovery was hydrolyzed in 1.5 mL of ammonia water:water = 1:1 mixed solution for 24 hours to recover the tung oil-based monomer with boric acid terminal group and the rosin-based monomer with boric acid terminal group, with a total monomer recovery rate of 83.9%.

[0038] Depend on Figure 5 It can be seen that Example 1 has the strongest tensile strength, while Example 2 has the weakest tensile strength. Example 1 is an elastomer, while Examples 2 and 3 are rigid solids.

Claims

1. A biobased resin that is closed loop recyclable, characterized in that, The chemical structure is shown as follows: wherein R is any one of the following groups: 。 2. The method of claim 1, wherein the ring-closable, recyclable bio-based resin is prepared by the steps of: The bio-based monomer with boronic acid end group is synthesized by mixing and dissolving bio-based polybasic acid and 4-carboxyphenylboronic acid, and then open ring addition reaction with ethylene glycol diglycidyl ether, and the chemical structure is shown as follows: wherein R is any one of the following groups: ； The bio-based resin which can be recycled by ring closure is prepared by dissolving the small molecule amine catalyst and the bio-based monomer with boronic acid end group in THF and DMF mixed solvent, and then heating and dehydration polymerization, and then removing the solvent.

3. The preparation method according to claim 2, characterized in that, The bio-based polybasic acid is one of azelaic acid, sebacic acid, brassylic acid, propenyl abietic acid, tung oil acid anhydride and maleic rosin.

4. The preparation method according to claim 2, characterized in that, The molar ratio of the bio-based polybasic acid, 4-carboxyphenylboronic acid and ethylene glycol diglycidyl ether is 1:n:n, wherein n is the number of carboxylic acid in the bio-based polybasic acid.

5. The preparation method according to claim 2, characterized in that, The solvent used in the open ring addition reaction is a mixture of water and DMF, the volume ratio is 1:2-1:6, the temperature is 90-130℃, and the reaction time is 6-24h.

6. The preparation method according to claim 2, characterized in that, The small molecule amine is one of diethanolamine (DEA), triethanolamine (TEA), serinol, N-methyl-2-pyrrolidone (NMP), and the molar ratio of the bio-based monomer with boronic acid end group and amine group is 1:1-1:

12.

7. The preparation method according to claim 2, characterized in that, The organic solvent used in the dehydration polymerization reaction is a mixture of THF and DMF, the volume ratio is 1:1-1:12, the oven temperature is 120-160℃, and the dehydration time is 24-48h.

8. The bio-based resin which can be recycled by ring closure of claim 1 can be used in the preparation of 3D printing ink, flexible sensor and friction generator material.

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