Method for reversely synthesizing polyol polyester based on dynamic DES microenvironment and intelligent separation technology

Abstract

The invention belongs to the technical field of biological catalytic synthesis, and provides a method for reversely synthesizing polyol polyester based on a dynamic DES microenvironment and an intelligent separation technology, and the method comprises the following steps: heating a hydrogen bond donor, a hydrogen bond acceptor and a microstructure regulating agent to form a clear solution to prepare the dynamic DES microenvironment; adding polyol, a dicarboxylate monomer, the pH response type amphiphilic copolymer and the immobilized lipase into a dynamic DES microenvironment, and carrying out heating reaction; and adjusting the pH value, adding an organic solvent, recovering the immobilized lipase, and carrying out supercritical CO2 extraction to separate the polyol polyester. According to the method disclosed by the invention, the reaction time is shortened by 40%, the maximum monomer conversion rate is up to 95.7%, and the enzyme stability is kept under a high-temperature condition; the dosage of an organic solvent is reduced by 80%, the DES recovery rate is greater than or equal to 97%, and the purification cost is remarkably reduced; the number-average molecular weight of the product is greater than or equal to 3500Da, the PDI is as low as 1.12, and the method is suitable for manufacturing high-end materials.

Description

Technical Field

[0001] The present invention relates to a method for reverse synthesizing polyol polyesters by combining a dynamic deep eutectic solvent (DES) microenvironment with intelligent separation technology and lipase, belonging to the technical field of biocatalytic synthesis. Background Art

[0002] In the field of polymer materials, polyol polyesters are an important type of synthetic material and are widely used in fields such as textiles, packaging, and biomedicine. Taking polyethylene succinate (PES) as an example, it is a polyol polyester with good biodegradability and mechanical properties and is widely used in fields such as degradable plastics, fibers, and films. However, traditional methods for synthesizing PES usually place succinic acid and ethylene glycol in a reaction kettle and carry out an esterification reaction using a catalyst at high temperature. The disadvantages of this method are long reaction time, high energy consumption, and the performance of the final product being limited by the catalyst and reaction conditions, which not only increases production costs but also limits the application of the product in some high-performance fields.

[0003] With the continuous expansion of the application of polyol polyesters in various fields, developing a green, efficient, and environmentally friendly method for synthesizing polyol polyesters has become an important research topic. In recent years, lipase catalysis technology has attracted attention due to its mild conditions and high selectivity, but it faces many challenges in reverse synthesizing polyol polyesters: the activity and stability of lipase in the non-aqueous phase are insufficient, which may lead to unsatisfactory catalytic effects; the poor solubility of substrates (such as polyols and dicarboxylic esters) significantly affects the reaction efficiency; the reaction system lacks a dynamic regulation mechanism, resulting in limited conversion rate and product polymerization degree, affecting the quality and performance of the final product. Summary of the Invention

[0004]

Technical Problem

[0005] In the prior art, there are problems such as insufficient activity and stability of lipase in the non-aqueous phase, difficulty in substrate solubility and product separation in the transesterification reaction system, and lack of a dynamic regulation mechanism in the reaction system, resulting in limited conversion rate and product polymerization degree.

[0006]

Technical Solution

[0007] To solve at least one of the above problems, the present invention uses a dynamic DES microenvironment combined with magnetically immobilized lipase to reverse synthesize polyol polyesters. Taking the synthesis of PES from ethylene glycol and dimethyl succinate as an example, combined with intelligent separation technology, it realizes efficient catalysis, enzyme recovery, and precise molecular weight regulation.

[0008] The first object of the present invention is to provide a method for reverse synthesizing polyol polyesters based on a dynamic DES microenvironment and intelligent separation technology, comprising the following steps:

[0009] S1. Heat the hydrogen bond donor, hydrogen bond acceptor, and microstructure regulator in a water bath with stirring until a clear solution is formed to prepare a dynamic DES microenvironment;

[0010] S2. Add polyol, dicarboxylate monomer, pH-responsive amphiphilic copolymer, and immobilized lipase to the dynamic DES microenvironment to obtain a reaction solution, and heat the reaction;

[0011] S3. Adjust the pH of the product of step S2, add an organic solvent, recover the immobilized lipase, and take the supernatant to extract and separate the polyol polyester with supercritical CO2.

[0012] In one embodiment of the present invention, in step S1, the hydrogen bond donor is glycerol (Gly) and polyethylene glycol 200 (PEG200).

[0013] In one embodiment of the present invention, in step S1, the hydrogen bond acceptor is choline chloride (ChCl).

[0014] In one embodiment of the present invention, in step S1, the molar ratio of choline chloride, glycerol, and polyethylene glycol 200 is 2:1:0.2 - 0.4 or 1:1:0.2 - 0.4.

[0015] In one embodiment of the present invention, in step S1, the molar ratio of choline chloride, glycerol, and polyethylene glycol 200 is preferably 2:1:0.3.

[0016] The microstructure regulator refers to a class of substances or methods that can precisely regulate the microstructure of materials through physical or chemical means. By changing the microstructural characteristics of materials such as crystallinity, phase state, defects, and interfaces, the macroscopic properties of materials are affected, such as mechanical strength, electrical conductivity, thermal conductivity, and optical properties.

[0017] In one embodiment of the present invention, in step S1, the microstructure regulator is selected from one of nanocellulose (NFC) and nanopolymer particles.

[0018] In one embodiment of the present invention, the nanopolymer particles are selected from one of polylactic acid nanoparticles and polystyrene nanospheres.

[0019] In one embodiment of the present invention, in step S1, the dosage of the microstructure regulator is 0.1 - 1 wt% of the total mass of the substrates (polyol and dicarboxylate in step S2).

[0020] In one embodiment of the present invention, in step S1, the temperature of the water bath heating is 60 - 85°C.

[0021] In one embodiment of the present invention, in step S2, the polyol is ethylene glycol or glycerol; the dicarboxylate monomer is dimethyl succinate or dimethyl adipate.

[0022] In one embodiment of the present invention, in step S2, the molar ratio of the polyol to the dicarboxylate monomer is 1:0.5 - 3.

[0023] In one embodiment of the present invention, in step S2, the dosage of the dynamic DES microenvironment is 10 - 100 wt% of the total mass of the substrate.

[0024] In one embodiment of the present invention, in step S2, the pH-responsive amphiphilic copolymer is selected from one or more of poly(ethylene oxide)-poly(propylene oxide) (Pluronic F127), poly(ε-caprolactone)-poly(ethylene glycol) (PCL-PEG), and poly(L-glutamic acid)-poly(ethylene glycol) (PGA-PEG).

[0025] In one embodiment of the present invention, in step S2, the dosage of the pH-responsive amphiphilic copolymer is 0.05 - 2 wt% of the total mass of the substrate.

[0026] In one embodiment of the present invention, in step S2, the immobilized lipase is magnetic immobilized lipase.

[0027] Magnetic immobilized lipase is a biocatalyst formed by immobilizing lipase on a magnetic carrier.

[0028] In one embodiment of the present invention, the carrier of the magnetic immobilized lipase is SiO₂-coated Fe₃O₄ (Fe₃O₄@SiO₂).

[0029] Fe₃O₄@SiO₂ is a core-shell structured nanomaterial that can be applied to the enzyme immobilization technology. Fe₃O₄@SiO₂ consists of two parts: a Fe₃O₄ magnetic core and a SiO₂ shell. Fe₃O₄ is the core part, whose main function is to provide magnetism so that the carrier can be quickly separated and recovered by an external magnetic field; SiO₂ is the outer layer, which acts to wrap around Fe₃O₄ to form a protective layer. The SiO₂ shell layer not only prevents Fe₃O₄ from being corroded in acidic or oxidizing environments, but also provides active sites for binding to lipase through surface modification (such as amination). Fe₃O₄@SiO₂ adopts a mesoporous structure design to increase its specific surface area, which helps to improve the lipase loading and catalytic efficiency.

[0030] In one embodiment of the present invention, in step S2, the enzyme activity of the immobilized lipase is 1500 - 1800 U / g; the carrier particle size is 45000 - 50100 nm; the dosage is 0.05 - 2 wt% of the total mass of the substrate.

[0031] In one embodiment of the present invention, in step S2, the temperature of the heating reaction is 50 - 75 °C; the heating reaction time is 6 - 8 h.

[0032] In one embodiment of the present invention, in step S2, the reaction is carried out in a low-frequency vibration reactor; the vibration frequency is 20-50 Hz; the amplitude is 0.2-0.7 mm.

[0033] In one embodiment of the present invention, the reaction liquid is cooled to below 40 °C before step S3 is carried out.

[0034] In one embodiment of the present invention, in step S3, the pH is adjusted to 4.8-5.2.

[0035] In one embodiment of the present invention, in step S3, the organic solvent is one or more of acetonitrile and methanol.

[0036] In one embodiment of the present invention, in step S3, the volume of the organic solvent is 1-3 times the volume of the dynamic DES microenvironment.

[0037] In one embodiment of the present invention, in step S3, after adding the organic solvent, the supernatant is obtained by ultrasonic treatment; the conditions of ultrasonic treatment are 20-60 kHz for 3-10 minutes.

[0038] In one embodiment of the present invention, in step S3, the conditions for supercritical CO2 extraction are: temperature 35-45 °C; pressure 9.5-10.5 MPa.

[0039] In one embodiment of the present invention, carbon quantum dots (CQDs) are added to the dynamic DES microenvironment in step S1, and the reaction liquid is irradiated with near-infrared light during the heating reaction in step S2.

[0040] In one embodiment of the present invention, the dosage of carbon quantum dots is 0.02-0.2 wt% of the total mass of the substrate.

[0041] In one embodiment of the present invention, the wavelength of the near-infrared light is 800-808 nm; the light power density of the near-infrared light irradiation is 0.8-1.2 W / cm 2 ; the heating reaction time is 5-8 h.

[0042] The second object of the present invention is to provide the polyol polyester prepared by the above method.

[0043] The third object of the present invention is to provide the application of the above polyol polyester in the textile field and precision injection molding.

[0044] In one embodiment of the present invention, the application includes home textiles, industrial textiles, and 3D printing materials.

[0045] Beneficial effects:

[0046] (1) The present invention uses a dynamic DES microenvironment combined with magnetic immobilized lipase for the reverse synthesis of polyol polyesters. The solvent is simple to prepare, low in cost, biodegradable, recyclable, and environmentally friendly.

[0047] (2) The present invention real-time regulates the conformation of lipase through a dynamic DES microenvironment and low-frequency vibration technology, and combines the characteristics of PEG200 of "protecting enzymes at low temperature and promoting reactions at high temperature", shortening the reaction time by 40%, with the highest conversion rate reaching 95.7%, and maintaining enzyme stability under high-temperature conditions.

[0048] (3) The present invention uses an intelligent separation technology through the synergistic action of a pH-responsive copolymer and supercritical CO2, reducing the amount of organic solvent used by 80%, and the DES recovery rate ≥ 97%, significantly reducing the purification cost.

[0049] (4) The present invention optimizes the substrate solubility and precisely regulates the molecular weight through a dynamic DES microenvironment. The number-average molecular weight (Mn) of the product ≥ 3500 Da, and the PDI is as low as 1.12, which is suitable for the manufacture of high-end materials. Description of the Drawings

[0050] Figure 1 It is the test result of Fourier transform infrared spectrometer (FTIR) of the polyol polyester obtained in Example 1;

[0051] Figure 2 It is the circular dichroism (CD) test of the magnetic immobilized lipase before and after low-frequency vibration in Example 1 and Comparative Example 2, and the diagram of the proportion of the secondary structure of lipase is detected. Detailed Embodiments

[0052] Test methods:

[0053] 1. Fourier transform infrared spectrometer (FTIR) test of polyol polyester

[0054] The polyol polyester generated by the reaction is ground into fine powder and mixed with potassium bromide for pressing tablets. Check the Fourier transform infrared spectrometer (FTIR), perform background scanning, set the scanning range from 4000 cm -1 to 400 cm -1 , perform spectral scanning, analyze the resulting spectrum, identify characteristic peaks and perform background subtraction and correction, and use software for peak fitting and quantitative analysis.

[0055] 2. High performance liquid chromatography (HPLC) test of dicarboxylate monomers

[0056] The test was carried out by high performance liquid chromatography (HPLC). Standard solutions of dicarboxylate monomers with different concentration gradients were prepared and a standard curve was plotted; after the reaction, the sample was filtered to remove insolubles, a C18 reversed-phase column chromatographic column, phosphoric acid aqueous solution and acetonitrile were selected as the mobile phase, the detection wavelength was set as the ultraviolet absorption wavelength, and the flow rate and gradient elution conditions were optimized. After injection, the peak area of the dicarboxylate monomer in the sample was recorded, and its concentration was calculated according to the standard curve. By comparing the concentration changes of the monomer before and after the reaction, its conversion rate was calculated.

[0057] 3. Mass spectrometry (MALDI-TOF MS) test of polyol polyester

[0058] The test was carried out by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS). An appropriate matrix, such as 2,5-dihydroxybenzoic acid (DHB), was selected, the polyol polyester generated by the reaction was mixed with the matrix and spotted on the MALDI target plate, and after drying, it was loaded into the instrument. In the MALDI-TOF MS instrument, analysis was carried out by adjusting the laser parameters, and the mass spectrum was recorded. By identifying the polymer peaks with different chain lengths, measuring their m / z values, the number-average molecular weight and the polydispersity index PDI were calculated.

[0059] 4. Circular dichroism (CD) test of lipase

[0060] Analysis was carried out by circular dichroism (CD) technology. Magnetic immobilized lipase solutions with the same concentration were prepared and dissolved in the dynamic DES microenvironment and traditional solvents respectively. The CD spectrometer was calibrated and the measurement wavelength range was set from 190 nm to 250 nm, and a quartz cuvette with a 1 cm optical path was used. Before measuring the sample, the baseline of the solvent was recorded to deduct the background signal, and the CD spectra of lipase under different conditions were measured in turn. The spectral data were analyzed by software, the secondary structure of the enzyme could be quantitatively analyzed, the percentages of the structures of different secondary structures (such as α-helix, β-sheet, etc.) were evaluated, and a mathematical model between the secondary structure content and the enzyme activity, such as a linear regression model, was established in combination with the experimentally determined enzyme activity data. In this way, when the contents of these components are known, the enzyme activity can be estimated.

[0061] Example 1

[0062] A method for reverse synthesis of polyol polyester based on dynamic DES microenvironment and intelligent separation technology, comprising the following steps:

[0063] (1) Preparation of dynamic DES microenvironment

[0064] The hydrogen bond acceptor choline chloride (ChCl, 14.0 g), the hydrogen bond donor glycerol (Gly, 9.0 g) and polyethylene glycol 200 (PEG200, 2.1 g) were mixed at a molar ratio of 2:1:0.3, and nanocellulose (NFC) was added to make it 0.5 wt% of the total substrate mass. It was stirred in a water bath at 70 °C for 2 h until it became clear and transparent, thus obtaining a dynamic DES microenvironment.

[0065] (2) Synthesis of polyol polyester:

[0066] The substrate polyol (ethylene glycol, 0.1 mol), the substrate dicarboxylate monomer (diethyl succinate, 0.2 mol), the pH-responsive amphiphilic copolymer (Pluronic F127, 0.5 g) and the magnetic immobilized lipase (Fe3O4@SiO2 support, 0.45 g, enzyme activity 1800 U / g) were added to 3 ml of the dynamic DES microenvironment, and reacted at 75 °C for 8 h in a low-frequency vibration reactor (40 Hz, 0.5 mm amplitude) to synthesize polyethylene glycol succinate.

[0067] (3) Intelligent purification:

[0068] After the reaction, the temperature was lowered to 40 °C, the pH was adjusted to 5.0, 5 ml of acetonitrile was added, and it was ultrasonically treated at 40 kHz for 5 minutes. The lipase was recovered by magnetic separation. The supernatant was taken and the product and DES were extracted and separated by supercritical CO2 (40 °C, 10 MPa) to obtain the white solid product polyethylene glycol succinate.

[0069] Comparative Example 1

[0070] The difference from Example 1 is that PEG200 and NFC were not used in step S1, that is, the dynamic DES microenvironment was replaced with a traditional DES (ChCl:Gly = 2:1).

[0071] Comparative Example 2

[0072] The difference from Example 1 is that free lipase was used to replace the magnetic immobilized lipase in step S2, and the low-frequency vibration technology was not used.

[0073] The test results of the infrared spectrometer (FTIR) of the polyol polyester prepared in Example 1 are as Figure 1 shown. The characteristic absorption peak of -OH is at 3677 cm -1 , indicating the presence of a hydroxyl structure in the synthesized product; the stretching vibration of -CH2 is at 2978 cm -1 , indicating the presence of a structure with a methylene carbon chain as the backbone in the synthesized product; the stretching vibration absorption peak of the carbonyl group in the ester bond is at 1722 cm -1 ; the stretching vibration absorption peaks of the ester bond are at 1165 and 1055 cm -1The absorption peak at [specific position] is for C-O stretching vibration, indicating the presence of ester bond structure in the synthesized product; at 549 cm -1 The absorption peak at [specific position] is due to the in-plane bending vibration of C-C=O. The presence of these characteristic peaks indicates that the synthesized product is poly(ethylene succinate).

[0074] The reaction mixtures of Example 1 and Comparative Examples 1-2 were tested by high performance liquid chromatography (HPLC) for dicarboxylate monomers, and the conversion rates of dicarboxylate monomers were calculated. The results are shown in Table 1.

[0075] Table 1 Test results of the conversion rates of dicarboxylate monomers in Example 1 and Comparative Examples 1 and 2

[0076]

[0077] It can be seen from the data in Table 1 that the conversion rate of Example 1 is as high as 92.6%, which is 19.8% and 30.3% higher than that of Comparative Example 1 (82.0%) and Comparative Example 2 (75.3%) respectively. This significant improvement is attributed to the non-linear viscosity reduction characteristic of the dynamic DES microenvironment, which optimizes the substrate mass transfer efficiency. The low-frequency vibration technology further enhances the exposure of the active sites of lipase, and the stability of the magnetic immobilized lipase avoids the inactivation problem of free enzymes. In Comparative Example 1, due to the lack of dynamic microenvironment regulation, the solvent viscosity is high, which limits the substrate diffusion. In Comparative Example 2, due to the absence of vibration assistance and immobilization technology, the enzyme conformation is not optimized and the stability is poor, resulting in a low conversion rate.

[0078] The polyol polyesters obtained from Example 1 and Comparative Examples 1-3 were tested by matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS), and the number-average molecular weight and polydispersity index (PDI) were calculated. The calculation results are shown in Table 2.

[0079] Table 2 Calculation results of the number-average molecular weight and polydispersity index (PDI) of the polyol polyesters prepared in Example 1 and Comparative Examples 1 and 2

[0080]

[0081] Table 2 shows that the number-average molecular weight (Mn) of Example 1 reaches 3500 Da and the PDI is as low as 1.12, which is significantly better than that of Comparative Example 1 (Mn = 2200 Da, PDI = 1.45) and Comparative Example 2 (Mn = 1800 Da, PDI = 1.67). The high molecular weight and narrow distribution of Example 1 benefit from the precise regulation of the dynamic DES microenvironment during the polymerization process. The "low-temperature enzyme protection and high-temperature reaction promotion" characteristic of PEG200 prolongs the catalytic life of lipase. The low-frequency vibration enhances the substrate selectivity, and the intelligent separation technology (supercritical CO2 extraction) effectively avoids the doping of by-products. In Comparative Example 1, due to the lack of PEG200 and NFC, the solvent viscosity fails to dynamically adapt to the reaction requirements, and the degree of polymerization is limited. In Comparative Example 2, due to the inactivation of free enzymes and the absence of vibration assistance, the polymerization reaction is incomplete and the molecular weight distribution is wide.

[0082] The lipases of Example 1 and Comparative Example 2 were subjected to circular dichroism (CD) tests, and the CD test results of the secondary structure of the lipases are as Figure 2 shown. Under the action of the dynamic DES microenvironment, the α-helix of the lipase increased significantly, while the β-sheet decreased. Since the α-helix structure has a certain rigidity and plays a supporting role in the overall conformation of some proteins, this may be one of the reasons for the increased catalytic effect of the lipase. In addition, the huge change in the lipase conformation may also affect its substrate pocket or other regions that play a key role in the catalytic cycle, thereby improving its efficiency.

[0083] Example 2

[0084] The difference from Example 1 is that in step S1, carbon quantum dots (CQDs) were added to the dynamic DES microenvironment, and the dosage of the carbon quantum dots was 0.1 wt% of the total mass of the substrate. And in step S2, when heating the reaction, the reaction solution was irradiated with near-infrared light (808 nm, 1 W / cm 2 ²), and the heating reaction time was 6 h.

[0085] The obtained reaction mixture and the polyol polyester were subjected to performance tests (high performance liquid chromatography (HPLC) test and matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF MS) test), and the conversion rate of the dicarboxylate monomer and the number-average molecular weight, polydispersity index PDI, and glass transition temperature Tg of the polyol polyester were calculated. The results are shown in Table 3.

[0086] Table 3 Comparison of the performances of Example 1 and Example 2

[0087] Parameter Example 1 (without photothermal) Example 2 (photothermal assisted) Monomer conversion rate (%) 92.6 95.3 Number-average molecular weight 3525 3630 PDI 1.12 1.1 Tg (°C) 65 85

[0088] Table 3 shows that near-infrared photothermal assistance increased Mn from 3500 Da to 3600 Da, decreased PDI from 1.12 to 1.1, and increased Tg by 20 °C. This is attributed to the fact that the photothermal effect of CQDs enhanced the local reaction temperature, promoted the efficient progress of the polymerization reaction, and at the same time, the regulation of the dynamic DES microenvironment further optimized the consistency of the molecular chain growth and improved the thermal stability of the product, which is applicable to high heat-resistant injection molding materials.

[0089] Example 3

[0090] The difference from Example 1 is that in step S1, the molar ratio of ChCl:Gly:PEG200 was adjusted to 2:1:0.2.

[0091] Example 4

[0092] The difference from Example 1 is that in step S1, the molar ratio of ChCl:Gly:PEG200 was adjusted to 2:1:0.4.

[0093] The obtained reaction mixture and polyol polyester were subjected to performance tests (liquid chromatography (HPLC) test and mass spectrometry (MALDI-TOF MS) test), and the conversion rate of dicarboxylate monomer and the number-average molecular weight, dispersion coefficient PDI and glass transition temperature Tg of polyol polyester were calculated. The calculation results are as follows:

[0094] Table 4 Calculation results of the conversion rate of dicarboxylate monomer, number-average molecular weight and PDI under different DES ratios

[0095] DES molar ratio 2:1:0.2 (Example 3) 2:1:0.3 (Example 1) 2:1:0.4 (Example 4) Monomer conversion rate (%) 85.3 92.6 88.7 Number-average molecular weight 3220 3525 3300 PDI 1.25 1.12 1.20

[0096] Table 4 shows that the conversion rate and Mn reached their peaks (92.6% and 3525 Da) at a molar ratio of 2:1:0.3, and the PDI was the lowest (1.12). When the PEG200 ratio was 0.2, the DES viscosity was relatively high (about 250 mPa·s), the substrate diffusion was limited, and the conversion rate and molecular weight were slightly lower; when the ratio increased to 0.4, the viscosity was too low (about 180 mPa·s), the conformational stability of lipase decreased, and the degree of polymerization decreased slightly. The ratio of 2:1:0.3 achieved the balance between solvent viscosity and enzyme activity through the optimal synergistic effect of PEG200 and NFC, and it was the optimal ratio.

[0097] Comparative Example 3

[0098] The difference from Example 1 was that in step S2, a dynamic DES microenvironment was not used.

[0099] Example 5

[0100] The difference from Example 1 was that in step S2, the amount of the dynamic DES microenvironment was 10% of the substrate mass.

[0101] Example 6

[0102] The difference from Example 1 was that in step S2, the amount of the dynamic DES microenvironment was 20% of the substrate mass.

[0103] Example 7

[0104] The difference from Example 1 was that in step S2, the amount of the dynamic DES microenvironment was 50% of the substrate mass.

[0105] The obtained reaction mixture and polyol polyester were subjected to performance tests (liquid chromatography (HPLC) test and mass spectrometry (MALDI-TOF MS) test), and the conversion rate of dicarboxylate monomer and the number-average molecular weight and dispersion coefficient PDI of polyol polyester were calculated. The calculation results are as follows:

[0106] Table 5 Calculation results of the conversion rate of dicarboxylate monomer, number-average molecular weight and PDI under different amounts of dynamic DES microenvironment

[0107]

[0108] As can be seen from Table 5, with the increase in the dosage of DES, the conversion rate of the dicarboxylate monomer, the number-average molecular weight of the polyol polyester, and the polydispersity index PDI all showed a trend of first increasing and then decreasing. When the dosage of DES reached 50%, that is, 1.5 ml, the conversion rate of the dicarboxylate monomer, the number-average molecular weight, and the polydispersity index PDI reached the maximum value, indicating that the dosage of 50% of the substrate dosage is the optimal dosage.

[0109] Example 8

[0110] The difference from Example 1 is that in step S2, the frequency of the low-frequency vibration reactor is 20 Hz.

[0111] Example 9

[0112] The difference from Example 1 is that in step S2, the frequency of the low-frequency vibration reactor is 60 Hz.

[0113] The obtained reaction mixture and polyol polyester were subjected to performance tests (liquid chromatography (HPLC) test and mass spectrometry (M-ALDI-TOF MS) test), and the conversion rate of the dicarboxylate monomer, the number-average molecular weight of the polyol polyester, the polydispersity index PDI, and the enzyme activity retention rate (%) were calculated. The calculation results are as follows:

[0114] Table 6 Calculation results of the conversion rate of the dicarboxylate monomer, the number-average molecular weight, PDI, and the enzyme activity retention rate at different vibration frequencies

[0115] Vibration frequency (Hz) 20 (Example 8) 40 (Example 1) 60 (Example 9) Monomer conversion rate (%) 86.7 92.6 89.5 Number-average molecular weight 3290 3525 3415 PDI 1.23 1.12 1.17 Enzyme activity retention rate (%) 93 95 92

[0116] Table 6 shows that when the vibration frequency is 40 Hz, the conversion rate (92.6%), Mn (3500 Da), and the enzyme activity retention rate (95%) all reach the best, and the PDI is the lowest (1.12). When the frequency is 20 Hz, the vibration energy is insufficient, the exposure degree of the active sites of the lipase is relatively low, and the conversion rate and the molecular weight slightly decrease; when the frequency is 60 Hz, the too high frequency may cause slight perturbation of the enzyme conformation, and the enzyme activity retention rate slightly decreases. At 40 Hz, through the input of appropriate mechanical energy, the conformation of the lipase and the contact efficiency with the substrate are optimally regulated.

[0117] The embodiments provided above are not intended to limit the scope covered by the present invention, nor are the described steps intended to limit the execution order. Obvious improvements made by those skilled in the art to the present invention in combination with the existing common general knowledge also fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for reverse synthesizing polyol polyesters based on a dynamic DES microenvironment and intelligent separation technology, characterized in that, It includes the following steps: S1. Water-bath heat and stir a hydrogen bond donor, a hydrogen bond acceptor, and a microstructure regulator until a clear solution is formed to obtain a dynamic DES microenvironment; S2. Add a polyol, a dicarboxylate monomer, a pH-responsive amphiphilic copolymer, and an immobilized lipase into the dynamic DES microenvironment to obtain a reaction solution, and heat for reaction; S3. Adjust the pH of the product of step S2, add an organic solvent, recover the immobilized lipase, and take the supernatant to extract and separate the polyol polyester with supercritical CO2.

2. The method according to claim 1, characterized in that In step S1, the hydrogen bond donor is glycerol and polyethylene glycol 200; the hydrogen bond acceptor is choline chloride; the molar ratio of choline chloride, glycerol, and polyethylene glycol 200 is 2:1:0.2 - 0.4 or 1:1:0.2 - 0.

4.

3. The method according to claim 1, characterized in that, In step S1, the microstructure regulator is selected from one of nanocellulose and nanopolymer particles; the dosage of the microstructure regulator is 0.1 - 1 wt% of the total mass of the substrates; the temperature of water-bath heating is 60 - 85 °C.

4. The method according to claim 1, wherein In step S2, the polyol is ethylene glycol or glycerol; the dicarboxylate monomer is dimethyl succinate or dimethyl adipate; the pH-responsive amphiphilic copolymer is selected from one or more of polyoxyethylene polyoxypropylene ether, polycaprolactone polyethylene glycol, and polyglutamic acid polyethylene glycol; the immobilized lipase is magnetic immobilized lipase.

5. The method according to claim 1, wherein In step S2, the molar ratio of the polyol to the dicarboxylate monomer is 1:0.5 - 3; the dosage of the dynamic DES microenvironment is 10 - 100 wt% of the total mass of the substrates; the dosage of the pH-responsive amphiphilic copolymer is 0.05 - 2 wt% of the total mass of the substrates; the enzyme activity of the immobilized lipase is 1500 - 1800 U / g; the carrier particle size is 45000 - 50100 nm; the dosage is 0.05 - 2 wt% of the total mass of the substrates.

6. The method according to claim 1, characterized in that, In step S2, the temperature of the heating reaction is 50 - 75 °C; the time of the heating reaction is 6 - 8 h; the reaction is carried out in a low-frequency vibration reactor; the vibration frequency is 20 - 50 Hz; the amplitude is 0.2 - 0.7 mm.

7. The method according to claim 1, wherein In step S3, adjusting the pH means adjusting the pH to 4.8 - 5.2; the organic solvent is one or more of acetonitrile and methanol; the conditions for supercritical CO2 extraction are: temperature 35 - 45 °C; pressure 9.5 - 10.5 MPa.

8. The method according to claim 1, wherein Add carbon quantum dots to the dynamic DES microenvironment in step S1, and irradiate the reaction solution with near-infrared light during the heating reaction in step S2; the dosage of the carbon quantum dots is 0.02-0.2 wt% of the total mass of the substrate; the wavelength of the near-infrared light is 800-808 nm; the light power density of the near-infrared light irradiation is 0.8-1.2 W / cm 2 ; the heating reaction time is 5-8 h.

9. The polyol polyester prepared by the method according to any one of claims 1 - 8.

10. The application of the polyol polyester according to claim 9 in the textile field and precision injection molding.

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