Meerwein type organic ion pair catalyst as well as preparation method and application thereof

Abstract

The invention discloses a Meerwein type organic ion pair catalyst as well as a preparation method and application thereof, and belongs to the technical field of polymer preparation. The invention relates to a preparation method of a Meerwein type organic ion pair catalyst, which comprises the following steps: in an inert atmosphere, taking 1-bromo-2, 3, 4, 5, 6-pentafluorobenzene, n-butyllithium, BCl3 and alkali metal salt as raw materials, carrying out stirring reaction, and then drying to prepare an intermediate product; dissolving [Me3O] < + > [BF4] <-> in an organic solvent, then adding the intermediate product into the organic solvent, carrying out an ionic reaction to generate a white precipitate, then carrying out solvent removal, filtering and separating the precipitate, concentrating, recrystallizing, washing and drying in sequence, and finally preparing [Me3O] < + > [B (C6F5) 4] <->, the catalyst is the Meerwein type organic ion pair catalyst. The synthesized catalyst can catalyze controllable cation ring-opening polymerization of monomers, and polyester which is excellent in thermal stability, free of metal residues and controllable in molecular weight and molecular weight distribution is prepared through solution polymerization or bulk polymerization. In addition, compared with a current commercial stannous isooctoate catalyst, the Meerwein type ion pair [Me3O] < + > [B (C6F5) 4] <-> organic catalyst provided by the invention has higher catalytic activity and lower biotoxicity.

Description

Technical Field

[0001] This invention belongs to the field of polymer preparation technology, and particularly relates to a Meerwein-type organic ion-pair catalyst, its preparation method, and its application. Background Technology

[0002] Catalysts used for the ring-opening polymerization of cyclic esters mainly include metal complexes and organic catalysts. In the field of ring-opening polymerization of cyclic esters, metal complex catalysts have made significant progress. Scientists have developed highly efficient catalytic systems based on various metals such as aluminum (Al), zirconium (Zr), titanium (Ti), zinc (Zn), scandium (Sc), and tin (Sn). Although these catalysts possess high catalytic activity and selectivity, they often leave metal residues in the polymer products, which severely limits the application of polyester materials in biological and medical fields. It is noteworthy that the current industrial synthesis of PCL (polycaprolactone) mainly uses Sn(Oct)₂ catalysts, while Sn… 2+ Residual issues remain a major technical bottleneck limiting its application in biomedicine.

[0003] To overcome the residue problems caused by metal catalysts, organic catalyst systems... ɛ -caprolactone, δ -Velolactone, L The application of organic bases in the ring-opening (co)polymerization of cyclic esters such as lactide and glycolide has attracted widespread attention. Significant progress has been made in the anionic ring-opening polymerization of cyclic esters catalyzed by organo-Lewis bases. Currently, a variety of organo-base catalysts have been developed. However, in the ring-opening polymerization of cyclic ester monomers with chiral centers, the active alkoxy anion chain terminus may induce racemization of the monomer and epimerization of the polymer chain, leading to a decrease in the isotacticity of the polymer. The synergistic catalytic system of organo-base / Lewis acid or hydrogen bond donor can, to some extent, suppress epimerization. The mechanism lies in the fact that Lewis acids and hydrogen bond donors can form hydrogen bonds with the alkoxy anion chain terminus, reducing the Lewis basicity of the active chain terminus. However, the hydrogen bond force is weak, and epimerization can recur under high-temperature conditions. Furthermore, organocatalyzed CROP (ring-opening polymerization) is also an effective method for synthesizing metal-free polyesters, but currently, Brønsted acid catalysts are mainly used. While these methods effectively address the issue of metal residues in polymers caused by metal complex catalysts, Brønsted acid catalysts are corrosive and require highly skilled operators and sophisticated reaction equipment. Therefore, developing metal-free Lewis acid catalytic systems for cyclic ester CROP is of significant research importance. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a Meerwein-type organic ion-pair catalyst, its preparation method, and its application.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A Meerwein-type organic ion-pair catalyst has the chemical formula [Me3O]. + [B(C6F5)4] - The structural formula is as follows: .

[0006] A method for preparing a Meerwein-type organic ion-pair catalyst includes the following steps: Under an inert atmosphere, 1-bromo-2,3,4,5,6-pentafluorobenzene, n-butyllithium, BCl3, and an alkali metal salt (potassium chloride) were reacted with stirring, followed by drying, to prepare the intermediate product ([K)). + [B(C6F5)4] - ); [Me3O] + [BF4] - The intermediate product is dissolved in an organic solvent, and then an ionic reaction is carried out to generate a white precipitate. The precipitate is then subjected to solvent removal, filtration, concentration, recrystallization, washing, and drying to obtain the Meerwein-type organic ion-pair catalyst.

[0007] Optionally, the molar ratio of 1-bromo-2,3,4,5,6-pentafluorobenzene to n-butyllithium is 1.1:1.

[0008] Optionally, the ionic reaction requires 72 h.

[0009] Optionally, the organic solvent is anhydrous dichloromethane.

[0010] Optionally, the undesirable solvent added during the recrystallization process is ultra-dry n-hexane with a water content of <0.2 ppm.

[0011] Furthermore, the preparation method specifically includes the following steps: (1) After evacuating the three-necked flask containing the magnetic inlet, fill it with N2 and repeat three times. Dissolve 1-bromo-2,3,4,5,6-pentafluorobenzene in anhydrous diethyl ether and lower the temperature of the reaction system to -72.0 ℃; n BuLi (n-butyllithium) was slowly added to the reaction system, and stirring was continued at this temperature for 1.5 h. Subsequently, BCl3 was added dropwise to the system over 20 min, followed by the addition of an alkali metal salt and H2O, and stirring was continued for 2 h. The product was dried at 150 °C for 48 h to obtain a white solid [K].+ [B(C6F5)4] - The reaction pathway is as follows: ; (2) In a glove box filled with N2, [Me3O] + [BF4] - Dissolve in an organic solvent (anhydrous dichloromethane), stir until homogeneous, and then add [K]. + [B(C6F5)4] - The reaction system was rapidly stirred at room temperature for 72 h to carry out the ionic reaction. During this period, a fine white precipitate (potassium tetrafluoroborate [K]) gradually formed. + [BF4] - After the reaction was complete, the solvent in the reaction system was removed under vacuum. The white residue was then thoroughly stirred and dissolved using 5.0 mL of DCM (dichloromethane), filtered, and the clear DCM solution was collected. The white filter residue was washed three times with 5.0 mL of DCM. The filtered DCM solutions were combined and concentrated to approximately 5.0 mL under reduced pressure. Subsequently, 10.0 mL of n-hexane was slowly added to the system, and the solution was placed in a refrigerator at -36.0 °C for recrystallization purification. After 24 h, the reaction system was filtered to obtain a pale yellow powder. The pale yellow solid was washed three times with 10.0 mL of a poor solvent (ultra-dry n-hexane) to obtain a white solid [Me3O]. + [B(C6F5)4] - [Me3O] was obtained by maintaining the mixture under vacuum for 12 hours to remove the solvent. + [B(C6F5)4] - The reaction pathway is as follows: .

[0012] The above-mentioned Meerwein-type organic ion-pair catalysts are used in the catalytic polymerization of cyclic ester monomers to prepare polyesters.

[0013] A method for preparing polyester based on a Meerwein-type organic ion-pair catalyst includes the following steps: The cyclic ester monomer and the above-mentioned Meerwein-type organic ion-pair catalyst were mixed and subjected to heating polymerization. A terminator was then added to terminate the reaction, yielding the polyester. The reaction route is as follows: ; In the above formula, n is the degree of polymerization, with a value range of 50-1,000,000; the number average molecular weight of the prepared polyester is 2.8 kDa~686.2 kDa, and the molecular weight distribution is 1.05~2.01.

[0014] Optionally, the molar ratio of the cyclic ester monomer to the Meerwein-type organic ion catalyst is 50-100000:1.

[0015] Optionally, the cyclic ester monomer is selected from... ɛ -caprolactone ( Formula 1) δ -valerolactone ( Formula 2), glycolide ( Equation 3) and L -lactide ( At least one of Formula 4).

[0016] Optionally, the conditions for the heating polymerization are: temperature 60 ~ 100 ℃, reaction time 1 ~ 96 h.

[0017] Optionally, the terminator is H2O.

[0018] Optionally, the heating polymerization conditions are: bulk polymerization under molten conditions, or solution polymerization using toluene or dichloromethane as solvent.

[0019] Furthermore, the bulk polymerization preparation process is as follows: [Me3O] is placed in a glove box filled with N2. + [B(C6F5)4] - The cyclic ester monomers were added to a sealable pressure-resistant tube equipped with a stirring magnet; then the pressure-resistant tube was placed in an oil bath for polymerization, the reaction temperature was lowered, and H2O terminator was added to the system to terminate the reaction; The solution polymerization preparation process is as follows: In a glove box filled with N2, [Me3O] is... + [B(C6F5)4] - Cyclic ester monomers and solvents are added to a sealable pressure-resistant tube equipped with a magnetic stir bar; then the pressure-resistant tube is placed in an oil bath for polymerization, the reaction temperature is lowered, and H2O terminator is added to the system, and the reaction is terminated by stirring thoroughly.

[0020] Furthermore, when preparing alternating copolyesters with the linear structure of Formula 5, the bulk polymerization described above is used to [Me3O]. + [B(C6F5)4] - As a catalyst for cationic ring-opening polymerization and condensation polymerization, it catalyzes the cationic ring-opening polymerization of α-caprolactone. After the reaction is completed, the resulting polymer is precipitated, filtered, and dried.

[0021] Formula 5 Furthermore, the precipitant used in the precipitation process is methanol; The polymerization temperature of the ring-opening polymerization is 60 ~ 100 ℃, more preferably 65 ℃; The polymerization time is 1 to 96 hours, more preferably 48 hours; The monomer α-caprolactone and the catalyst [Me3O] + [B(C6F5)4] - The feed ratio is 50 / 1 to 1,000,000 / 1, more preferably 100 / 1; The tin content in the polyester with the structure of Formula 5 is less than 10 mg / kg; n is the degree of polymerization, ranging from 50 to 1,000,000.

[0022] Furthermore, when preparing alternating copolyesters with the linear structure of Formula 6, bulk polymerization is employed to [Me3O] + [B(C6F5)4] - As a catalyst for cationic ring-opening polymerization and condensation polymerization, it catalyzes the cationic ring-opening polymerization of δ-valerolactone. After the reaction is completed, the resulting polymer is precipitated, filtered, and dried.

[0023] Formula 6 Furthermore, the precipitant used in the precipitation process is methanol; The polymerization temperature of the ring-opening polymerization is 60 ~ 100 ℃, more preferably 65 ℃; The polymerization time is 1 to 96 hours, more preferably 48 hours.

[0024] The monomer δ-valerolactone and the catalyst [Me3O] + [B(C6F5)4] - The feed ratio is 50 / 1 to 1,000,000 / 1, more preferably 100 / 1; The tin content in the polyester with the Formula 6 structure is less than 10 mg / kg; n is the degree of polymerization, ranging from 50 to 1,000,000.

[0025] Furthermore, when preparing alternating copolyesters with the linear structure of Formula 7, bulk polymerization is employed to [Me3O]. + [B(C6F5)4] - As a catalyst for cationic ring-opening polymerization and condensation polymerization, it catalyzes the cationic ring-opening polymerization of lactide. After the reaction is completed, the resulting polymer is precipitated, filtered, and dried.

[0026] Formula 7 Furthermore, the precipitant used in the precipitation process is methanol; The polymerization temperature of the ring-opening polymerization is 60 ~ 100 ℃, more preferably 100 ℃; The polymerization time is 1 to 96 hours, more preferably 24 hours.

[0027] The monomer lactide and the catalyst [Me3O] + [B(C6F5)4] - The feed ratio is 50 / 1 to 1,000,000 / 1, more preferably 100 / 1; The tin content in the polyester having the Formula 7 structure is less than 10 mg / kg; n is the degree of polymerization, ranging from 50 to 1,000,000.

[0028] Furthermore, when preparing alternating copolyesters with the linear structure of Formula 8, bulk polymerization is employed to [Me3O] + [B(C6F5)4] - As a catalyst for cationic ring-opening polymerization and condensation polymerization, it catalyzes the cationic ring-opening polymerization of glycolide. After the reaction is completed, the resulting polymer is precipitated, filtered, and dried.

[0029] Formula 8 Furthermore, the precipitant used in the precipitation process is methanol; The polymerization temperature of the ring-opening polymerization is 60 ~ 100 ℃, more preferably 100 ℃; The polymerization time is 1 to 96 hours, more preferably 12 hours.

[0030] Monomer glycolide and catalyst [Me3O] + [B(C6F5)4] - The feed ratio is 50 / 1 to 1,000,000 / 1, more preferably 100 / 1; The tin content in the polyester with Formula 8 structure is less than 10 mg / kg; n is the degree of polymerization, ranging from 50 to 1,000,000.

[0031] Furthermore, when preparing copolyesters with the linear structure of Formula 9, bulk polymerization is employed to obtain [Me3O]. + [B(C6F5)4] - As a catalyst for cationic ring-opening polymerization and condensation polymerization, catalysis L - Cationic ring-opening (co) polymerization of lactide and glycolide. After the reaction is complete, the resulting polymer is precipitated, filtered, and dried.

[0032] Formula 9 In Formula 9 above, n and m are the degrees of polymerization of polyglycolic acid and poly-L-lactide, respectively. n is the degree of polymerization of polyglycolic acid, ranging from 25 to 500,000; m is the degree of polymerization of polylactide, ranging from 25 to 500,000; and the length ratio (n:m) of polyglycolic acid and polylactide blocks in the polymer ranges from 1:99 to 50:50, more preferably 5:95.

[0033] Furthermore, the precipitant used in the precipitation process is methanol; The polymer temperature is 60 ~ 100 ℃, more preferably 80 ℃; The polymerization time is 1 to 96 h, more preferably 16 h.

[0034] Monomers L-lactide and glycolide with catalyst [Me3O] + [B(C6F5)4] - The feeding ratio is (25+25) / 1 ~ (500000+500000) / 1, more preferably (50+50) / 1; The tin content in the polyester having the Formula 9 structure is less than 10 mg / kg.

[0035] Furthermore, when preparing copolyesters with the linear structure of Formula 10, bulk polymerization is employed to obtain [Me3O]. + [B(C6F5)4] - As a catalyst for cationic ring-opening polymerization and condensation polymerization, it catalyzes the cationic ring-opening polymerization of L-lactide and α-caprolactone. After the reaction is completed, the resulting polymer is precipitated, filtered, and dried.

[0036] Formula 10 In Formula 10, n and m are the degrees of polymerization of poly(α-caprolactone) and poly(L-lactide), respectively. n is the degree of polymerization of polycaprolactone, ranging from 50 to 1,000,000; m is the degree of polymerization of polylactide, ranging from 50 to 1,000,000; the length ratio of polycaprolactone and polylactide blocks in the polymer is (1 / 99) to (99 / 1), more preferably 80 / 20.

[0037] Furthermore, the precipitant used in the precipitation process is methanol; The polymerization temperature of the ring-opening polymerization is 60 ~ 100 ℃, more preferably 80 ℃; The polymerization time is 1 to 96 hours, more preferably 24 hours; Monomers L-lactide and α-caprolactone with the catalyst [Me3O] + [B(C6F5)4] -The feeding ratio is 50 / 1 to 1,000,000 / 1, more preferably 100 / 1; The tin content in the polyester having the Formula 10 structure is less than 10 mg / kg.

[0038] Furthermore, when preparing copolyesters with the linear structure of Formula 11, bulk polymerization is employed to obtain [Me3O]. + [B(C6F5)4] - As a catalyst for cationic ring-opening polymerization and condensation polymerization, it catalyzes the cationic ring-opening polymerization of δ-valerolactone and α-caprolactone. After the reaction is completed, the resulting polymer is precipitated, filtered, and dried.

[0039] Formula 11 In Formula 11, n and m are the degrees of polymerization of polyα-caprolactone and polyδ-valactone, respectively. n is the degree of polymerization of polycaprolactone, ranging from 50 to 1,000,000; m is the degree of polymerization of polyvalactone, ranging from 50 to 1,000,000; the length ratio of polyglycolic acid and polyvalactone blocks in the polymer is (1 / 99) to (99 / 1), more preferably 80 / 20.

[0040] Furthermore, the precipitant used in the precipitation process is methanol; The polymerization temperature of the ring-opening polymerization is 60 ~ 100 ℃, more preferably 80 ℃; The polymerization time is 1 to 96 hours, more preferably 24 hours; Monomers α-caprolactone and δ-valerolactone with the catalyst [Me3O] + [B(C6F5)4] - The feeding ratio is 50 / 1 to 1,000,000 / 1, more preferably 100 / 1; The tin content in the polyester having the structure of Formula 11 is less than 10 mg / kg.

[0041] Compared with the prior art, the present invention has the following advantages and technical effects: This invention discloses a sterically hindered Meerwein-type organic ion pair [Me3O]. + [B(C6F5)4] - And it is used as a cationic catalyst for catalyzing cyclic esters ( ɛ -caprolactone, δ -Velolactone, LThe cationic ring-opening (co)polymerization of monomers such as lactide and glycolide was used to prepare (co)polyesters with diverse structures. During polymerization, the monomer conversion rate was 87–99%; the resulting polyesters had molecular weights between 2.8 kDa and 686.2 kDa, with a molecular weight distribution of 1.05–2.01. Under the same polymerization conditions, the smaller anionic [Me3O]... + [BF4] - Catalyst, Catalysis ɛ -caprolactone and δ -Velolactone cationic ring-opening polymerization monomer conversion is only 5-12%, and it cannot effectively catalyze glycolide and... L - Cationic ring-opening polymerization of lactide.

[0042] Furthermore, compared with the stannous octoate catalyst, the organic catalyst used in this invention produces a polyester that is metal-free.

[0043] In summary, by using the sterically hindered Meerwein-type organic ion pair of this invention as a cationic ring-opening polymerization catalyst to catalyze the cationic ring-opening (co)polymerization of cyclic ester monomers, it is possible to prepare (co)polyesters with diverse structures and no metal residues. Attached Figure Description

[0044] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The polyester structures with Formula I prepared by Examples 1-12 of this invention are examples of applications of this invention. 1 H NMR spectrum; Figure 2 The polyester structures with Formula I prepared by Examples 1-12 of this invention are examples of applications of this invention. 13 C NMR spectrum; Figure 3 The polyester structures with Formula II prepared by Examples 13-16 of this invention are examples of applications of this invention. 1 H NMR spectrum; Figure 4 The polyester structures with Formula II prepared by Examples 13-16 of this invention are examples of applications of this invention. 13 C NMR spectrum; Figure 5 The polyester structures with Formula III prepared by Examples 17-19 of this invention are examples of applications of this invention. 1 H NMR spectrum; Figure 6 The polyester structures with Formula III prepared by Examples 17-19 of this invention are examples of applications of this invention. 13C NMR spectrum; Figure 7 The polyester structures with Formula IV prepared in Examples 20-22 of this invention are examples of applications of this invention. 1 H NMR spectrum; Figure 8 The polyester structures with Formula IV prepared in Examples 20-22 of this invention are examples of applications of this invention. 13 C NMR spectrum; Figure 9 The thermal and mechanical properties of the polyester prepared in the application example of this invention and the polyester prepared by Sn(Oct)2 as a catalyst were tested; where (a) is the DSC diagram; (b) is the TGA diagram; (c) is the breaking strength; and (d) is the elongation at break. Figure 10 This is a ball-and-stick structure diagram of the sterically hindered Meerwein-type organic ion-pair catalyst prepared in Example 1 of the present invention. Figure 11 The sterically hindered Meerwein-type organic ion-pair catalyst prepared in Example 1 of this invention 1 H NMR spectrum. Detailed Implementation

[0045] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0046] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0047] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0048] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0049] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0050] This invention employs a low-steric-impedance Meerwein-type organic ion pair [Me3O]. + [B(C6F5)4] - In the process of preparing polyesters with diverse structures by cationic ring-opening (co)polymerization of catalytic cyclic ester monomers, all operations sensitive to moisture and oxygen are performed by professionals in this field under nitrogen protection in an Etelux Lab2000 glove box or using standard Schlenk techniques.

[0051] The present invention conducted relevant tests on the obtained polymer, using nuclear magnetic resonance spectroscopy to determine the polymer's microstructure and gel permeation chromatography to determine the polymer's molecular weight and molecular weight distribution index. The polymer... 1 ¹H NMR was determined by a Bruker-400 NMR spectrometer at 25 °C, with TMS as the internal standard and deuterated chloroform as the solvent. Gel permeation chromatography was performed using a Waters gel permeation chromatograph. Tetrahydrofuran (THF) was used as the solvent (with 0.05 wt% 2,6-di-tert-butyl-4-methylphenol added as an antioxidant). The test temperature was 40 °C, the flow rate was 1.0 mL / min, and PL EasiCal PS-1 was used as the standard.

[0052] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0053] All raw materials used in this invention were purchased from the market.

[0054] The technical solution of the present invention will be further illustrated by the following embodiments.

[0055] Example 1 A method for preparing a Meerwein-type organic ion-pair catalyst includes the following steps: (1) After evacuating the three-necked flask containing the magnetic ingot, fill it with N2 and repeat three times. Dissolve 22.0 mmol of 1-bromo-2,3,4,5,6-pentafluorobenzene in 80 ml of anhydrous diethyl ether and lower the temperature of the reaction system to -72.0 ℃; dissolve 8.4 mL of 2.4 M of a solution containing... nA hexane solution of BuLi (n-butyllithium) was slowly added to the reaction system, and stirring was continued at this temperature for 1.5 h. Subsequently, 5.0 mL of 1.0 M BCl3 was added dropwise to the system over 20 min, followed by the addition of 40.0 mmol of potassium chloride and 80.0 mL of H2O, and stirring was continued for 2 h. The product was dried at 150 °C for 48 h to obtain a white solid [K]. + [B(C6F5)4] - (Yield rate 47.2%) (2) In a glove box filled with N2, add 0.80 mmol [Me3O] + [BF4] - Dissolve in 10 mL of anhydrous dichloromethane, stir well, and then add 0.84 mmol [K]. + [B(C6F5)4] - The reaction system was rapidly stirred at room temperature for 72 h to allow for the ionic reaction. During this period, a fine white precipitate (potassium tetrafluoroborate [K]) gradually formed. + [BF4] - After the reaction was complete, the solvent was removed from the reaction system under vacuum. The white residue was then thoroughly stirred and dissolved using 5.0 mL of DCM, filtered, and the clear DCM solution was collected. The white filter residue was washed three times with 5.0 mL of DCM. The filtered DCM solutions were combined and concentrated to approximately 5.0 mL under reduced pressure. Subsequently, 10.0 mL of n-hexane was slowly added to the system, and the solution was placed in a refrigerator at -36.0 °C for recrystallization purification. After 24 h, the reaction system was filtered to obtain a pale yellow powder. The pale yellow solid was washed three times with 10.0 mL of a poor solvent (ultra-dry n-hexane). A white solid [Me3O] was obtained. + [B(C6F5)4] - [Me3O] was obtained by maintaining the mixture under vacuum for 12 hours to remove the solvent. + [B(C6F5)4] - .

[0056] Figure 10 This is a ball-and-stick structure diagram of the sterically hindered Meerwein-type organic ion-pair catalyst prepared in Example 1 of the present invention. Figure 11 The sterically hindered Meerwein-type organic ion-pair catalyst prepared in Example 1 of this invention 1 H NMR spectrum.

[0057] The sterically hindered Meerwein-type organic ion pair [Me3O] prepared in Example 1 was used. +[B(C6F5)4] - As a catalyst, the following polyesters were prepared: Application Example 1 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.1 equivalent) of catalyst and α-caprolactone (2000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 65°C.

[0058] (2) After polymerization has proceeded for an appropriate time (36 h), the reaction temperature is lowered (to 30 °C), and H2O terminator is added to the system, followed by thorough stirring. DCM is then added to the reaction system to fully dissolve it, and the mixture is slowly added dropwise to methanol for back precipitation. After stirring for a period of time (60 min), the polymer is separated from the methanol by filtering the DCM or centrifugation. The resulting polymer is dried at 40 °C for 24 h.

[0059] The polymerization was carried out for 36 hours, and the conversion rate of α-caprolactone monomer reached 96%. The final product was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 1 of this invention is a polyester with the structure of Formula I. The polymer has a molecular weight of 20.5 kDa and a molecular weight distribution of 1.23.

[0060] Formula I Application Example 2 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.05 equivalent) of catalyst and α-caprolactone (4000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 80°C.

[0061] (2) After polymerization for an appropriate time (48 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time (60 min), the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0062] The polymerization was carried out for 48 hours, and the conversion rate of α-caprolactone monomer reached 93%. The final product was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 2 of this invention is a polyester with the structure of Formula I, wherein the polymer molecular weight is 30.1 kDa and the molecular weight distribution is 1.31.

[0063] Application Example 3 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.025 equivalent) catalyst and α-caprolactone (8000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 100°C.

[0064] (2) After polymerization for an appropriate time (48 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0065] The polymerization was carried out for 48 hours, and the conversion rate of α-caprolactone monomer reached 90%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 3 of this invention is a polyester with the structure of Formula I, wherein the polymer molecular weight is 41.6 kDa and the molecular weight distribution is 1.48.

[0066] Application Example 4 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4]- (2 mmol, 0.02 equivalent) catalyst and α-caprolactone (1000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 65°C.

[0067] (2) After polymerization for an appropriate time (12 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0068] The polymerization was carried out for 12 hours, and the conversion rate of α-caprolactone monomer reached 98%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 4 of this invention is a polyester with the structure of Formula I, wherein the polymer molecular weight is 16.3 kDa and the molecular weight distribution is 1.18.

[0069] Application Example 5 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.4 equivalents) of catalyst and α-caprolactone (500 mmol, 100.0 equivalents) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 80°C.

[0070] (2) After polymerization has proceeded for an appropriate time (24 h), the reaction temperature is lowered (to 30 °C), and H2O terminator is added to the system, followed by thorough stirring. DCM is then added to the reaction system to fully dissolve it, and the mixture is slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer is separated from the methanol by filtration or centrifugation. The resulting polymer is dried at 40 °C for 24 h.

[0071] The polymerization was carried out for 24 hours, and the conversion rate of α-caprolactone monomer reached 96%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 5 of this invention is a polyester with the structure of Formula I, wherein the polymer molecular weight is 8.5 kDa and the molecular weight distribution is 1.15.

[0072] Application Example 6 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. +[B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.4 equivalent) catalyst and α-caprolactone (500 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 60°C.

[0073] (2) After polymerization has proceeded for an appropriate time (8 h), the reaction temperature is lowered (to 30 °C), and H2O terminator is added to the system, followed by thorough stirring. DCM is then added to the reaction system to fully dissolve it, and the mixture is slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer is separated from the methanol by filtration or centrifugation. The resulting polymer is dried at 40 °C for 24 h.

[0074] The polymerization was carried out for 8 hours, and the conversion rate of α-caprolactone monomer reached 95%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 6 of this invention is a polyester with the structure of Formula I, wherein the polymer molecular weight is 9.6 kDa and the molecular weight distribution is 1.12.

[0075] Application Example 7 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.4 equivalent) catalyst, α-caprolactone (500 mmol, 100.0 equivalent), and dichloromethane were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 60°C.

[0076] (2) After polymerization for an appropriate time (12 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0077] The polymerization was carried out for 12 hours, and the conversion rate of α-caprolactone monomer reached 96%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 7 of this invention is a polyester with a structure of Formula I, wherein the polymer molecular weight is 11.2 kDa and the molecular weight distribution is 1.10.

[0078] Application Example 8 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.4 equivalent) catalyst, α-caprolactone (500 mmol, 100.0 equivalent), and toluene were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 60°C.

[0079] (2) After polymerization has proceeded for an appropriate time (8 h), the reaction temperature is lowered (to 30 °C), and H2O terminator is added to the system, followed by thorough stirring. DCM is then added to the reaction system to fully dissolve it, and the mixture is slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer is separated from the methanol by filtration or centrifugation. The resulting polymer is dried at 40 °C for 24 h.

[0080] The polymerization was carried out for 8 hours, and the conversion rate of α-caprolactone monomer reached 96%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 8 of this invention is a polyester with a structure of Formula I, wherein the polymer molecular weight is 11.5 kDa and the molecular weight distribution is 1.10.

[0081] Application Example 9 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.001 equivalent) catalyst, α-caprolactone (200,000 mmol, 100.0 equivalent), and toluene were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 60°C.

[0082] (2) After polymerization for an appropriate time (96 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0083] The polymerization was carried out for 96 hours, and the conversion rate of α-caprolactone monomer reached 92%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 9 of this invention is a polyester with a structure of Formula I, wherein the polymer molecular weight is 686.2 kDa and the molecular weight distribution is 2.01.

[0084] Application Example 10 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.001 equivalent) of catalyst and α-caprolactone (2000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 60°C.

[0085] (2) After polymerization has proceeded for an appropriate time (24 h), the reaction temperature is lowered (to 30 °C), and H2O terminator is added to the system, followed by thorough stirring. DCM is then added to the reaction system to fully dissolve it, and the mixture is slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer is separated from the methanol by filtration or centrifugation. The resulting polymer is dried at 40 °C for 24 h.

[0086] The polymerization was carried out for 24 hours, and the conversion rate of α-caprolactone monomer reached 93%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 10 of this invention is a polyester with a structure of Formula I, wherein the polymer molecular weight is 80.4 kDa and the molecular weight distribution is 1.78.

[0087] Application Example 11 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] -(2 mmol, 0.001 equivalent) of catalyst and α-caprolactone (4000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 60°C.

[0088] (2) After polymerization for an appropriate time (36 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0089] The polymerization was carried out for 36 hours, and the conversion rate of α-caprolactone monomer reached 92%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 11 of this invention is a polyester with a structure of Formula I, wherein the polymer molecular weight is 147.6 kDa and the molecular weight distribution is 1.87.

[0090] Application Example 12 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.001 equivalent) catalyst and α-caprolactone (6000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 60°C.

[0091] (2) After polymerization for an appropriate time (48 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0092] The polymerization was carried out for 48 h, and the conversion rate of α-caprolactone monomer reached 93%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 12 of this invention is a polyester with a structure of Formula I, wherein the polymer molecular weight is 201.8 kDa and the molecular weight distribution is 2.00.

[0093] Figure 1-2 The NMR spectra of the polyester structures with Formula I prepared by Application Examples 1-12 of this invention are shown.

[0094] Application Example 13 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polyvalerol as a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.1 equivalent) of catalyst and δ-valerolactone (2000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a stirring magnet. The pressure-resistant tube was then placed in an oil bath at 65°C.

[0095] (2) After polymerization for an appropriate time (38 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0096] The polymerization was carried out for 38 hours, and the conversion rate of δ-valerolactone monomer reached 98%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 13 of this invention is a polyester with a structure of Formula II, wherein the polymer molecular weight is 19.5 kDa and the molecular weight distribution is 1.25.

[0097] Formula II Application Example 14 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polyvalerol as a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.05 equivalent) of catalyst and δ-valerolactone (4000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a stirring magnet. The pressure-resistant tube was then placed in an oil bath at 80°C.

[0098] (2) After polymerization for an appropriate time (36 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0099] The polymerization was carried out for 36 hours, and the conversion rate of δ-valerolactone monomer reached 95%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 14 of this invention is a polyester with a structure of Formula II, wherein the polymer molecular weight is 28.9 kDa and the molecular weight distribution is 1.35.

[0100] Application Example 15 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polyvalerol as a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.025 equivalent) catalyst and δ-valerolactone (8000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a stirring magnet. The pressure-resistant tube was then placed in an oil bath at 100°C.

[0101] (2) After polymerization for an appropriate time (48 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0102] The polymerization was carried out for 48 h, and the conversion rate of δ-valerolactone monomer reached 89%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 15 of this invention is a polyester with a structure of Formula II, wherein the polymer molecular weight is 40.1 kDa and the molecular weight distribution is 1.50.

[0103] Application Example 16 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polyvalerol as a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] -(2 mmol, 0.025 equivalent) catalyst and δ-valerolactone (10000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a stirring magnet. The pressure-resistant tube was then placed in an oil bath at 100°C.

[0104] (2) After polymerization for an appropriate time (48 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0105] The polymerization was carried out for 48 h, and the conversion rate of δ-valerolactone monomer reached 89%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 16 of this invention is a polyester with a structure of Formula II, wherein the polymer molecular weight is 186.2 kDa and the molecular weight distribution is 1.77.

[0106] Figure 3-4 The NMR spectra of the polyester structures with Formula II prepared in Examples 13-16 of this invention are shown.

[0107] Application Example 17 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polylactic acid using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.1 equivalent) of catalyst and L-lactide (2000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 80°C.

[0108] (2) After polymerization for an appropriate time (40 h), the reaction temperature was lowered, and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0109] The polymerization process lasted for 40 hours. L- The conversion rate of lactide monomer reached 95%. The obtained product was subjected to GPC and NMR analysis. Example 17 of this invention yielded a polyester with a structure of Formula III, wherein the polymer molecular weight was 18.9 kDa and the molecular weight distribution was 1.35. Furthermore, the polylactic acid prepared by this invention has a highly isotactic chain structure.

[0110] Formula III Application Example 18 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polylactic acid using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.05 equivalent) catalyst and L-lactide (4000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 80°C.

[0111] (2) After polymerization for an appropriate time (36 h), the reaction temperature was lowered, and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0112] The polymerization process lasted 36 hours. L - The conversion rate of lactide monomer reached 95%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 18 of this invention is a polyester with a structure of Formula III, wherein the polymer molecular weight is 29.5 kDa and the molecular weight distribution is 1.37.

[0113] Application Example 19 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polylactic acid using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.025 equivalent) catalyst and L - Lactide (8000 mmol, 100.0 equivalent) was added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 100°C.

[0114] (2) After polymerization for an appropriate time (48 h), the reaction temperature was lowered, and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0115] The polymerization process lasted 48 hours. L - The conversion rate of lactide monomer reached 89%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Application Example 15 of this invention is a polyester with a structure of Formula III, wherein the polymer molecular weight is 41.3 kDa and the molecular weight distribution is 1.51.

[0116] Figure 5-6 The NMR spectra of the polyester structures with Formula III prepared in Application Examples 17-19 of this invention are shown.

[0117] Application Example 20 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polylactide and polyglycolic acid copolymers using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.1 equivalent) of catalyst and L-lactide and glycolide (total molar amount of the two esters: 2000 mmol, 100.0 equivalent; wherein the molar ratio of L-lactide and glycolide is 1:1) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 80°C.

[0118] (2) After polymerization for an appropriate time (40 h), the reaction temperature was lowered, and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0119] The polymerization process lasted for 40 hours. L - The conversion rates of lactide and glycolide monomers were 68% and 96%, respectively. The products obtained were subjected to GPC and NMR analysis. Application Example 20 of this invention yielded a polyester with a structure of formula IV, wherein the polymer molecular weight was 18.5 kDa and the molecular weight distribution was 1.66.

[0120] Formula IV Application Example 21 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polylactide and polyglycolic acid copolymers using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.05 equivalent) catalyst and L-lactide and glycolide (total molar amount of the two esters: 4000 mmol, 100.0 equivalent; molar ratio of L-lactide to glycolide: 1:1) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 80°C.

[0121] (2) After polymerization for an appropriate time (36 h), the reaction temperature was lowered, and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0122] The polymerization process lasted 36 hours. L The conversion rates of lactide and glycolide monomers were 67% and 95%, respectively. The products obtained were subjected to GPC and NMR analysis. The product obtained in Application Example 21 of this invention was a polyester with a structure of formula IV, wherein the polymer molecular weight was 29.1 kDa and the molecular weight distribution was 1.27.

[0123] Application Example 22 The sterically hindered Meerwein-type organic ion pair [Me3O] was employed. + [B(C6F5)4] - The process for preparing polylactide and polyglycolic acid copolymers using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [B(C6F5)4] - (2 mmol, 0.025 equivalent) catalyst and L - Lactose and glycolide (the total molar amount of the two esters is 8000 mmol, 100.0 equivalents; of which, L - A molar ratio of lactide and glycolide of 1:1 is added to a sealable pressure-resistant tube equipped with a stirring magnet. The pressure-resistant tube is then placed in an oil bath at 100°C.

[0124] (2) After polymerization for an appropriate time (48 h), the reaction temperature was lowered, and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0125] The polymerization process lasted 48 hours. L The conversion rates of lactide and glycolide monomers were 61% and 91%, respectively. The products obtained were subjected to GPC and NMR analysis. The product obtained in Application Example 22 of this invention was a polyester with a structure of formula IV, wherein the polymer molecular weight was 40.3 kDa and the molecular weight distribution was 1.51.

[0126] Figure 7 The polyester structures with Formula IV prepared in Examples 20-22 of this invention are examples of applications of this invention. 1 H NMR spectrum.

[0127] Figure 8 The polyester structures with Formula IV prepared in Examples 20-22 of this invention are examples of applications of this invention. 13 C10 NMR spectrum.

[0128] Comparative Example 1 Using [Me3O] + [BF4] - The process for preparing polycaprolactone using a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [BF4] - (2 mmol, 0.1 equivalent) of catalyst and α-caprolactone (2000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a magnetic stir bar. The pressure-resistant tube was then placed in an oil bath at 65°C.

[0129] (2) After polymerization has proceeded for an appropriate time (36 h), the reaction temperature is lowered (to 30 °C), and H2O terminator is added to the system, followed by thorough stirring. DCM is then added to the reaction system to fully dissolve it, and the mixture is slowly added dropwise to methanol for back precipitation. After stirring for a period of time (60 min), the polymer is separated from the methanol by filtering the DCM or centrifugation. The resulting polymer is dried at 40 °C for 24 h.

[0130] The polymerization was carried out for 36 hours, and the conversion rate of α-caprolactone monomer reached 5%. The final product was subjected to GPC analysis and NMR analysis. The product obtained in Comparative Example 1 of this invention is a polyester with the structure of Formula I. The polymer has a molecular weight of 2.1 kDa and a molecular weight distribution of 1.16.

[0131] Comparative Example 2 Using [Me3O] + [BF4] - The process for preparing polyvalerol as a catalyst is as follows: (1) In a glove box filled with N2, [Me3O] + [BF4] - (2 mmol, 0.05 equivalent) of catalyst and δ-valerolactone (4000 mmol, 100.0 equivalent) were added to a sealable pressure-resistant tube equipped with a stirring magnet. The pressure-resistant tube was then placed in an oil bath at 80°C.

[0132] (2) After polymerization for an appropriate time (36 h), the reaction temperature was lowered (to 30 °C), and H2O terminator was added to the system, followed by thorough stirring. DCM was then added to the reaction system to fully dissolve it, and the mixture was slowly added dropwise to methanol for back precipitation. After stirring for a period of time, the polymer was separated from the methanol by filtration or centrifugation. The resulting polymer was dried at 40 °C for 24 h.

[0133] The polymerization was carried out for 36 h, and the conversion rate of δ-valerolactone monomer reached 11%. The product obtained above was subjected to GPC analysis and NMR analysis. The product obtained in Comparative Example 2 of this invention is a polyester with a structure of Formula II, wherein the polymer molecular weight is 1.7 kDa and the molecular weight distribution is 1.09.

[0134] Effect verification: I. For those using the above [Me3O] + [B(C6F5)4] - The thermal properties of PCL and PVL samples prepared by catalytic bulk polymerization were investigated. For comparison, the bulk polymerization synthesis of α-CL using Sn(Oct)₂ catalyst was also studied. M n PCL of 224.1 kDa and M n The PVL concentration was 186.2 kDa. For ease of subsequent research, the samples were named PCL-80.4 kDa ([Me3O)). + [B(C6F5)4] - Synthesized as a catalyst M n PCL (polycaprolactone) with a strength of 80.4 kDa, and PCL-147.6 kDa ([Me3O)) + [B(C6F5)4] - Synthesized as a catalyst M n PCL of 147.6 kDa), PCL-201.8 kDa ([Me3O])+ [B(C6F5)4] - Synthesized as a catalyst M n (PCL of 201.8 kDa), PVL of 186.2 kDa ([Me3O]) + [B(C6F5)4] - Synthesized as a catalyst M n The synthesis was carried out using PVL (polyvalerol) (186.2 kDa) and PCL-Sn-224.1 kDa (Sn(Oct)2) as catalysts. M n (PCL of 224.1 kDa).

[0135] The thermal properties of the above five samples were investigated, and DSC tests revealed (e.g.) Figure 9 As shown in (a): PCL-80.4 kDa, PCL-147.6 kDa and PCL-201.8 kDa T m Within the range of 55.5℃ - 57.8℃, with the PCL M n The growth rate improved slightly. However, the PCL sample (PCL-Sn-224.1 kDa) prepared using Sn(Oct)2 as a catalyst showed a slight increase. T m Lower than PCL-201.8 kDa. PVL-186.2 kDa has a melting point of 55.5℃. TGA test results for the polymer show (e.g.) Figure 9 As shown in (b), the PCL-80.4 kDa sample lost 5 wt% at a temperature of 361℃, while the PCL-147.6 kDa and PCL-201.8 kDa samples lost 5 wt% at temperatures of 377℃ and 379℃, respectively, indicating that thermal stability improved with increasing polymer molecular weight. However, the PCL-Sn-224.1 kDa sample lost only 5 wt% at a temperature of 358℃, which may be due to residual Sn in the polymer. 2+ The catalyst accelerated the depolymerization reaction of the polymer at high temperatures. The PVL-186.2 kDa sample lost 5 wt% of its weight at 342 °C. These results demonstrate that the [Me3O] catalyst... + [B(C6F5)4] -Metal-free PCL synthesized using Sn(Oct)2 as a catalyst exhibits superior thermal stability compared to PCL synthesized using Sn(Oct)2 as a catalyst. In particular, while PCL-201.8 kDa and PCL-Sn-224.1 kDa have similar molecular weights, the former demonstrates significantly better thermal stability, with a 5 wt% weight loss temperature exceeding that of the latter by more than 20.0 °C. This provides important evidence for the synthesis of highly stable metal-free PCL.

[0136] II. The mechanical properties of the above five samples were tested through tensile tests.

[0137] like Figure 9 As shown in (c) and (d), the fracture strengths of the PCL-80.4 kDa, PCL-147.6 kDa, and PCL-201.8 kDa samples are 27 MPa, 36 MPa, and 51 MPa, respectively, with elongations at break of 850%, 1100%, and 1520%, respectively. The mechanical properties significantly improve with increasing molecular weight. However, although the PCL-Sn-224.1 kDa sample has a higher molecular weight than the PCL-201.8 kDa sample, its fracture strength is only 35 MPa, and its elongation at break is only 980%, significantly lower than the metal-free PCL-201.8 kDa sample. The PVL-186.2 kDa sample has a fracture strength of 47 MPa and an elongation at break of 1350%.

[0138] The test results of the high molecular weight polyester synthesized by the above bulk polymerization sufficiently demonstrate that [Me3O] + [B(C6F5)4] - As a catalyst, high molecular weight polymers synthesized via bulk polymerization exhibit superior thermal stability and mechanical properties. This invention utilizes [Me3O]. + [B(C6F5)4] - Using catalytic bulk polymerization of cyclic esters as a catalyst provides a new method for synthesizing polyester materials with high thermal stability and high molecular weight.

[0139] In summary, this invention prepares a sterically hindered Meerwein-type organic ion pair [Me3O]. + [B(C6F5)4] - And applied to ɛ -caprolactone, δ -valerol and L - Cationic ring-opening polymerization of cyclic ester monomers such as lactide is used to prepare thermally stable polyesters with no metal residues.

[0140] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A Meerwein-type organic ion pair catalyst, characterized by, trimethyloxonium tetrapentafluorophenylborate [Me3O] + [B(C6F5)4] - , the structural formula of which is as follows: 。 2. A process for the preparation of a Meerwein-type organic ion pair catalyst, characterized in that, The method comprises the following steps: An intermediate product is prepared by stirring reaction under inert atmosphere, using 1-bromo-2,3,4,5,6-pentafluorobenzene, n-butyllithium, BCl3 and alkali metal salt as raw materials, and then drying; [Me3O] + [BF4] - The intermediate product is dissolved in an organic solvent, and then an ionic reaction is carried out to generate a white precipitate. The precipitate is then subjected to solvent removal, filtration, concentration, recrystallization, washing, and drying to obtain the Meerwein-type organic ion-pair catalyst as described in claim 1.

3. The process for the preparation of Meerwein-type organic ion pair catalyst according to claim 2, characterized in that, The molar ratio of the 1-bromo-2,3,4,5,6-pentafluorobenzene to the n-butyllithium is 1.1:

1.

4. The process for the preparation of Meerwein-type organic ion pair catalyst according to claim 2, characterized in that, The ion reaction time is 72 h.

5. The process for the preparation of Meerwein-type organic ion pair catalyst according to claim 2, wherein, The poor solvent added in the recrystallization process is super-dry n-hexane, and the water content is less than 0.2 ppm.

6. Application of the Meerwein-type organic ion pair catalyst in catalyzing polymerization of cyclic ester monomers to prepare a polyester.

7. A process for the preparation of a polyester based on a Meerwein-type organic ion pair catalyst, characterized in that, The method comprises the following steps: The cyclic ester monomer and the Meerwein-type organic ion pair catalyst are mixed, heated and polymerized, a terminating agent is added into the reaction system to terminate the reaction, and finally the polyester is prepared; The number average molecular weight of the polyester is 2.8 kDa to 686.2 kDa, and the molecular weight distribution is 1.05 to 2.

01.

8. The process for the preparation of a polyester based on a Meerwein-type organic ion pair catalyst according to claim 7, characterized in that, The molar ratio of the cyclic ester monomer to the Meerwein-type organic ion pair catalyst is (50-100000):

1.

9. The process for the preparation of a polyester based on Meerwein-type organic ion pair catalyst according to claim 7, characterized in that, The cyclic ester monomers are selected from at least one of ɛ - caprolactone, δ - valerolactone, glycolide or L - lactide.

10. The process for the preparation of a polyester based on Meerwein-type organic ion pair catalyst according to claim 7, characterized in that, The polymerization temperature is 60-100 ℃, and the reaction time is 1-96 h.

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