A method for the preparation of a performance tunable polyester from a PET alcoholysis product, poly(ethylene glycol terephthalate) by hydroxyl-yne click polymerization
By using the hydroxy-alkynyl click polymerization of bis(hydroxyethyl) terephthalate, a product of PET alcoholysis, a polyester material with adjustable properties was prepared, solving the problems of high energy consumption and metal residue in traditional PET recycling methods and realizing efficient and environmentally friendly PET reuse.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-04-09
- Publication Date
- 2026-06-09
AI Technical Summary
Traditional PET recycling methods are energy-intensive, have difficult-to-remove byproducts, and leave metal residues that pose environmental and health risks. They also rely on non-renewable fossil resources, resulting in low PET recycling rates and microplastic pollution.
A polyester material with a well-defined structure and tunable properties was prepared by using the hydroxy-alkynyl click polymerization of bis(hydroxyethyl) terephthalate, a product of PET alcoholysis, via click polymerization at room temperature using an organic catalyst.
It has enabled the transformation of PET into high-value functional polymers. Polyester materials have good thermal stability and mechanical properties, and can be transformed from semi-crystalline materials into amorphous materials with precise performance control.
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Figure CN122167714A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for preparing a performance-tunable polyester by hydroxy-alkynyl click polymerization of bis(2-hydroxyethyl) terephthalate (BHET), a product of PET alcoholysis. It is a method for preparing a novel polyester with a well-defined structure, specific stereoconfiguration, and tunable properties by using bis(2-hydroxyethyl) terephthalate (BHET), a product of waste PET alcoholysis, as a raw material through an organic catalytic "hydroxy-alkynyl" click polymerization reaction. Background Technology
[0002] Polyester is a class of polymeric materials produced by the stepwise polymerization of dicarboxylic acids (or their derivatives) and diols, with ester groups in the main chain. It possesses excellent mechanical properties, weather resistance, chemical resistance, and processability, making it an indispensable core material in packaging, textiles, automotive, medical, and electronics industries. In the packaging industry, polyethylene terephthalate (PET) is widely used in beverage bottles, food films, and pharmaceutical packaging due to its excellent barrier properties, transparency, and lightweight characteristics, with an annual global production exceeding 70 million tons. In the textile sector, polyester fibers account for more than 60% of the synthetic fiber market, used in clothing, home textiles, and industrial fabrics. In the automotive sector, polyester composites are used in interior parts, structural components, and lightweight car bodies. In the medical field, its biocompatibility and sterilizability make it an ideal choice for surgical sutures, vascular stents, and drug delivery systems. In the electronics field, polyester films, due to their high insulation and thermal stability, are widely used in flexible circuit boards, liquid crystal displays, and solar cell backsheets.
[0003] Traditional polyester synthesis mainly relies on melt polycondensation of petroleum-based dicarboxylic acids (such as terephthalic acid) and diols (such as ethylene glycol), typically requiring temperatures of 250–280 °C. oThe process is carried out at high temperatures in the presence of metal catalysts (such as antimony and titanium compounds). This process is energy-intensive, difficult to completely remove byproducts leading to a wide molecular weight distribution, and metal residues pose environmental and health risks. Furthermore, it is highly dependent on non-renewable fossil resources. With the escalating global plastic pollution crisis, the traditional linear "production-use-disposal" economic model is no longer sustainable. Globally, approximately 400 million tons of plastic waste are generated annually, with a PET recycling rate of less than 30%. Large quantities of waste enter the ocean and soil, causing microplastic pollution and ecological damage. Traditional PET recycling methods, such as mechanical and chemical recycling, have many limitations. Mechanical recycling, through crushing, washing, and remelting PET waste, inevitably leads to a decrease in molecular weight and thermal stability, limiting the application range of recycled PET. While chemical recycling can convert PET into monomers through depolymerization, it typically requires high-temperature, high-pressure conditions and corrosive reagents, resulting in high costs and safety hazards. Therefore, developing an efficient, environmentally friendly, and economical method for PET recycling and reuse is of great significance. To address these challenges, green synthesis technologies and research on novel polyesters with tunable properties have become hot topics in polymer science. Summary of the Invention
[0004] The purpose of this invention is to provide a method for preparing performance-tunable polyesters by hydroxy-alkynyl click polymerization of bis(hydroxyethyl) terephthalate, a product of PET alcoholysis. This method can synthesize a series of structurally rich, performance-tunable, and selectively degradable functional polymers, realizing the transformation of PET into high-value functional polymers, while solving the technical difficulties and environmental problems in traditional PET recycling methods.
[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a property-tunable polyester by hydroxy-yne click polymerization of bis(hydroxyethyl) terephthalate, a product of PET alcoholysis, comprises the following steps: Bis(2-hydroxyethyl) terephthalate (BHET) was added to a solvent and stirred at room temperature until dissolved. An organic catalyst was then added to obtain the reaction system. Separately, a difunctional propynyl ester monomer was dissolved in a solvent to prepare a solution, which was slowly added dropwise to the above reaction system. After the addition was complete, the reaction was continued to be stirred at room temperature. After the reaction was completed, the resulting mixture was added to a precipitation solvent, resulting in a precipitate. The precipitate was obtained by filtration and drying. The crude product was then vacuum dried to obtain a polyester material with tunable properties.
[0006] The molar ratio of BHET to the difunctional propynyl ester monomer is 1:1 to 1:1.3.
[0007] The solvent is tetrahydrofuran (THF), dichloromethane (CH2Cl2), or dimethyl sulfoxide (DMSO).
[0008] The organic catalyst is one or a mixture of two or more of the following: triethylamine (Et3N), 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD).
[0009] The molar percentage concentration of the organic catalyst in the reaction system is 5-15%.
[0010] The reaction temperature is 0~40℃. o C, the reaction time is 0.5~2 hours.
[0011] The precipitating solvent is methanol, and the separation yield is 92-98%.
[0012] The difunctional propynate monomer has one of the following structural formulas: The beneficial effects of this invention are: Using BHET as a raw material, a number-average molecular weight polymer was prepared by click polymerization of hydroxy-yne. M n The polymer dispersion is 10.8–14.2 kg / mol. Đ A series of structurally well-defined, stereospecific, and performance-tunable polyester materials with a thermal stability (T3–4.3) were synthesized. The synthesized polyester materials exhibit good thermal stability (T3). d5% >335 o C, T g 24–54 o C). By controlling the length and type of diol chains in difunctional propynyl esters, polymers can be transformed from semi-crystalline materials to amorphous materials, achieving precise control over the properties from brittle materials to rigid plastics and then to highly ductile elastomers. Attached Figure Description
[0013] Figure 1 Thermogravimetric analysis (TGA) curves for P1a-BHET to P1e-BHET are shown.
[0014] Figure 2 The differential scanning calorimetry (DSC) curves from P1a-BHET to P1e-BHET are shown. The solid line represents the second heating curve, and the dashed line represents the first heating curve.
[0015] Figure 3 X-ray diffraction (XRD) patterns of P1a-BHET to P1e-BHET.
[0016] Figure 4The stress-strain curves are for P1b-BHET, P1c-BHET, P1d-BHET, and P1e-BHET.
[0017] Figure 5 For different number-average molecular weights ( M n The stress-strain curve of P1e-BHET.
[0018] Figure 6 The cyclic tensile test curves (10 cycles) of P1e-BHET under the condition of 62% maximum strain.
[0019] Figure 7 This is a technical roadmap of the present invention. Detailed Implementation
[0020] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.
[0021] The technical route of the method of the present invention is as follows: Figure 7 As shown.
[0022] 1. Organocatalytic polymerization of BHET with difunctional acetylacetic acid esters Table 1. Organic-catalyzed click polymerization of BHET with difunctional alkyne esters "hydroxy-alkynyl". [a]
[0023] Example 1: Synthesis of P1a-BHET Bis(2-hydroxyethyl) terephthalate (BHET, 1.270 g, 5.0 mmol, 1.0 equivalent) was added to 5 mL of tetrahydrofuran (THF) and stirred at room temperature until dissolved. Then, 1,4-diazabicyclo[2.2.2]octane (DABCO, 0.50 mmol, 10 mol%) was added. The reaction flask was cooled in an ice-water bath. A separate THF solution of monomer 1a (0.831 g, 5.0 mmol, 1.0 equivalent) was prepared (dissolved in 5 mL of THF) and slowly added dropwise to the above reaction system using a syringe under ice-water conditions. After the addition was complete, the ice-water bath was removed, and the mixture was stirred vigorously at room temperature for 1 hour. After the reaction was complete, the reaction mixture was poured into a 250 mL Erlenmeyer flask containing a large amount of methanol (approximately 150–200 mL) and stirred rapidly to precipitate. After the polymer precipitation was complete, it was filtered through a sintered glass funnel, washed with methanol (3 × 30 mL), and then heated at 40 °C. o Drying under high vacuum for 24 hours yielded a pure polymer product, P1a-BHET, which was a white to off-white solid.
[0024] Example 2: Synthesis of P1b-BHET Add BHET (1.270 g, 5.0 mmol, 1.0 equivalent) to 5 mL of CH2Cl2 and stir at room temperature until dissolved. Then add DBU (0.250 mmol, 5 mol%). Cool the reaction flask in an ice-water bath. Prepare a CH2Cl2 solution of monomer 1b (0.901 g, 5.0 mmol, 1.3 equivalent) (dissolved in 5 mL of CH2Cl2) and slowly add it dropwise to the above reaction system using a syringe under ice-water conditions. After the addition is complete, remove the ice-water bath and allow the mixture to continue stirring vigorously at 40°C for 2 hours. After the reaction is complete, pour the reaction mixture into a 250 mL Erlenmeyer flask containing a large amount of methanol (approximately 150–200 mL) and stir rapidly to precipitate. Filter through a sintered glass funnel, wash with methanol (3 × 30 mL), and then at 40°C. o Drying under high vacuum for 24 hours yielded a pure polymer product, P1b-BHET, which was a white to off-white solid.
[0025] Example 3: Synthesis of P1c-BHET Add BHET (1.270 g, 5.0 mmol, 1.0 equivalent) to 5 mL of DMSO and stir at room temperature until dissolved. Then add Et3N (0.75 mmol, 15 mol%). Cool the reaction flask in an ice-water bath. Prepare a DMSO solution of 1c monomer (0.971 g, 5.0 mmol, 1.0 equivalent) (dissolved in 5 mL of DMSO) and slowly add it dropwise to the above reaction system using a syringe while in an ice bath. After the addition is complete, remove the ice-water bath and allow the mixture to reach 0°C. o Continue stirring vigorously at C for 0.5 hours. After the reaction is complete, pour the reaction mixture into a 250 mL Erlenmeyer flask containing a large amount of methanol (approximately 150–200 mL) and stir rapidly to precipitate. Filter using a sintered glass funnel, wash with methanol (3 × 30 mL), and then at 40 °C. o After drying under high vacuum for 24 hours, the pure polymer product P1c-BHET was obtained, which was a white to off-white solid.
[0026] Example 4: Synthesis of P1d-BHET Add BHET (1.270 g, 5.0 mmol, 1.0 equivalent) to 5 mL of THF and stir at room temperature until dissolved. Then add MTBD (0.50 mmol, 10 mol%). Cool the reaction flask in an ice-water bath. Prepare a THF solution of 1d monomer (1.050 g, 5.0 mmol, 1.0 equivalent) (dissolved in 5 mL of THF) and slowly add it dropwise to the above reaction system using a syringe while in an ice bath. After the addition is complete, remove the ice-water bath and continue to stir vigorously at room temperature for 1 hour. After the reaction is complete, pour the reaction mixture into a polytetrafluoroethylene beaker containing a large amount of methanol (about 150–200 mL) and stir rapidly to precipitate. After the polymer has precipitated, carefully discard the supernatant, wash with methanol (3 × 30 mL), and rinse at 40°C. o After drying under high vacuum for 24 hours, a pure polymer product, P1d-BHET, was obtained, which was a yellow-black, sticky, waxy solid.
[0027] Example 5: Synthesis of P1e-BHET Add BHET (1.270 g, 5.0 mmol, 1.0 equivalent) to 5 mL of THF and stir at room temperature until dissolved. Then add DABCO (0.750 mmol, 16 mol%). Cool the reaction flask in an ice-water bath. Prepare a THF solution of 1e monomer (1.270 g, 5.0 mmol, 1.2 equivalent) (dissolved in 5 mL of THF) and slowly add it dropwise to the above reaction system using a syringe while in an ice bath. After the addition is complete, remove the ice-water bath and continue to stir vigorously at room temperature for 2 hours. After the reaction is complete, pour the reaction mixture into a polytetrafluoroethylene beaker containing a large amount of methanol (approximately 150–200 mL) and stir rapidly to precipitate. After the polymer has precipitated, carefully discard the supernatant, wash with methanol (3 × 30 mL), and rinse at 40°C. o After drying under high vacuum for 24 hours, the pure polymer product P1e-BHET was obtained, which was a yellow-black sticky waxy solid.
[0028] P1a-BHET: 1 H NMR (500 MHz, CDCl3) δ 8.09 (s, 4H), 7.63 (d, J = 12.5 Hz, 2H), 5.28 (d, J = 12.5 Hz, 2H), 4.60 (s, 4H), 4.32 (s, 4H), 4.19 (s, 4H). 13 C NMR (126 MHz, CDCl3) δ152.24, 76.09, 74.07, 63.15. P1b-BHET: 1 H NMR (400 MHz, CDCl3) δ 8.08 (d, J = 17.2 Hz, 4H), 7.62 (d, J =11.5 Hz, 2H), 5.26 (d, J = 12.6 Hz, 2H), 4.61 (s, 4H), 4.19 (s, 8H), 1.99 (s,2H). 13 C NMR (126 MHz, CDCl3) δ 152.61, 75.27, 74.50, 62.58, 27.48. P1c-BHET: 1 H NMR (500 MHz, CDCl3) δ 8.06 (s, 4H), 7.58 (d, J = 12.3 Hz, 2H), 5.23 (d, J = 12.3 Hz, 2H), 4.76 – 4.40 (m, 4H), 4.16 (s, 4H), 4.10 (s,4H),1.68 (s, 2H). 13 C NMR (126 MHz, CDCl3) δ 152.72, 75.02, 74.63, 65.60, 24.97. P1d-BHET: 1 H NMR (400 MHz, CDCl3) δ 8.09 (s, 4H), 7.63 (d, J = 12.6 Hz,2H), 5.39 – 5.17 (m, 2H), 4.59 (s, 2H), 4.31 – 4.21 (m, 4H), 4.18 (s, 4H),3.78 – 3.59 (m, 4H), 1.84 (s, 2H). 13 C NMR (126 MHz, CDCl3) δ 152.61, 75.49, 74.48, 68.60, 65.08. P1e-BHET: 1 H NMR (400 MHz, CDCl3) δ 8.07 (s, 4H), 7.61 (d, J = 12.5 Hz, 2H), 5.27 (d, J = 12.6 Hz, 2H), 4.57 (s, 4H), 4.24 (s, 4H), 4.16 (s, 4H), 3.68 (s, 4H), 3.62 (s, 4H). 13 C NMR (126 MHz, CDCl3) δ 152.69, 75.34, 74.59, 70.73, 68.69, 65.26. 2. Thermal properties of polymers The prepared polymer was further tested for thermodynamic properties using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Figure 1 and Figure 2 As shown, the glass transition temperature of P1a-BHET is 53.91°C. o C, the temperature at which 5% weight loss occurs is 335.01. o C. The glass transition temperature of P1b-BHET is 44.87°C. o C, in 111 o A melting peak appears at temperature C, with a melting enthalpy of -48.01 J / g, and the temperature at which 5% weight loss occurs is 360.10. o C. The glass transition temperature of P1c-BHET is 37.58 °C. o C, in 77 o A melting peak appears at temperature C, with a melting enthalpy of -20.78 J / g, and the temperature at which 5% weight loss occurs is 353.62. o C. The glass transition temperature of P1d-BHET is 36.22°C. o The temperature at which 5% weight loss occurs is 349.68°C. o C. The glass transition temperature of P1e-BHET is 24.24°C. o The temperature at which 5% weight loss occurs is 361.74°C. o C.
[0029] X-ray diffraction (XRD) analysis further tested the polymer crystallization behavior: P1b-BHET and P1c-BHET are semi-crystalline polymers, with obvious crystallization diffraction peaks. P1a-BHET, P1d-BHET, and P1e-BHET are amorphous polymers, with no obvious diffraction peaks observed. Figure 3 ).
[0030] 3. Mechanical properties of polymers All prepared polymers can be molded into dumbbell-shaped test strips using a plate vulcanizer, and their mechanical properties can then be tested using a universal testing machine. For example... Figure 4 As shown: P1b-BHET (based on propylene glycol) exhibits obvious yield behavior followed by significant strain hardening, with a fracture strength of approximately (51.4 ± 0.2) MPa and an elongation at break exceeding (429.7 ± 2.4)%; P1c-BHET (based on butanediol) also has a yield plateau, with a fracture strength of approximately (41.7 ± 5.4) MPa and an elongation at break of approximately (504.1 ± 32.6)%; P1d-BHET (based on diethylene glycol) shows no obvious yield, with a fracture strength of approximately (42.0 ± 7.4) MPa and an elongation at break exceeding (443.8 ± 39.7)%; P1e-BHET (based on triethylene glycol) is a non-yielding elastomer, with a fracture strength of approximately (17.5 ± 0.8) MPa and an elongation at break exceeding (1050 ± 45)%. It is worth noting that P1a-BHET (based on ethylene glycol) material is quite brittle and is prone to brittle fracture in room temperature tensile tests, making it impossible to obtain a complete stress-strain curve.
[0031] Taking P1e-BHET as an example, the effect of molecular weight on its mechanical properties was further investigated. When the number average molecular weight (... M n When the concentration of the polymer (PP) increased from 11.1 kg / mol to 32.3 kg / mol, the tensile strength of the material increased from approximately 17.4 MPa to approximately 18.5 MPa, while the elongation at break decreased slightly from approximately 1060% to approximately 900%. Figure 5 ).like Figure 6 As shown: P1e-BHET material can maintain a stress recovery rate of over 60% after 10 cycles of tensile testing.
Claims
1. A method for preparing a performance-tunable polyester by hydroxy-alkyne click polymerization of bis(hydroxyethyl) terephthalate, a product of PET alcoholysis, characterized in that, The steps are as follows: Bis(2-hydroxyethyl) terephthalate (BHET) was added to a solvent and stirred at room temperature to dissolve it. An organic catalyst was then added to obtain the reaction system. Separately, a difunctional propynyl ester monomer was dissolved in a solvent to prepare a solution, which was slowly added dropwise to the above reaction system. After the addition was complete, the reaction was stirred at room temperature. After the reaction was completed, the mixture obtained from the reaction was added to a precipitation solvent to produce a precipitate. The precipitate was filtered and dried to obtain a crude product. The crude product was then vacuum dried to obtain a polyester material with adjustable properties.
2. The method for preparing performance-tunable polyester by hydroxy-alkyne click polymerization of bis(hydroxyethyl) terephthalate, a PET alcoholysis product, according to claim 1, is characterized in that... The molar ratio of BHET to the difunctional propynyl ester monomer is 1:1 to 1:1.
3.
3. A method for preparing a performance-tunable polyester by hydroxy-alkyne click polymerization of bis(hydroxyethyl) terephthalate, a PET alcoholysis product, according to claim 1 or 2, characterized in that, The solvent is tetrahydrofuran, dichloromethane, or dimethyl sulfoxide.
4. A method for preparing a performance-tunable polyester by hydroxy-alkyne click polymerization of bis(hydroxyethyl) terephthalate, a PET alcoholysis product, according to claim 1 or 2, characterized in that, The organic catalyst is one or a mixture of two or more of the following: triethylamine, 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD).
5. A method for preparing a performance-tunable polyester by hydroxy-alkyne click polymerization of bis(hydroxyethyl) terephthalate, a product of PET alcoholysis, according to claim 1 or 2, characterized in that, The molar percentage concentration of the organic catalyst in the reaction system is 5-15%.
6. A method for preparing a performance-tunable polyester by hydroxy-alkyne click polymerization of bis(hydroxyethyl) terephthalate, a PET alcoholysis product, according to claim 1 or 2, characterized in that, The reaction temperature is 0~40℃. o C, the reaction time is 0.5~2 hours.
7. A method for preparing a performance-tunable polyester by hydroxy-alkyne click polymerization of bis(hydroxyethyl) terephthalate, a product of PET alcoholysis, according to claim 1 or 2, characterized in that, The precipitating solvent is methanol.
8. A method for preparing a performance-tunable polyester by hydroxy-alkyne click polymerization of PET alcoholysis product diethyl terephthalate according to claim 1 or 2, characterized in that, The difunctional propynate monomer has one of the following structural formulas: 。