Application of organic boron and guanidine / phosphazene base combined catalyst and high molecular weight polyester synthesis method

Abstract

The invention discloses application of an organic boron and guanidine / phosphazene base combined catalyst and a high-molecular-weight polyester synthesis method, relates to the technical field of polyester synthesis catalysis, and solves the problems of low polymerization rate, limited monomer application, over-wide molecular weight distribution and the like in the prior art. The high-molecular-weight polyester is synthesized on the basis of efficient and controllable ring-opening copolymerization of cheap monomers including styrene oxide / vinyl ethylene oxide and phthalic anhydride. The number-average molecular weight of the high-molecular-weight polyester is 5.02 thousands to 16.33 thousands, and the molecular weight distribution is 1.22-1.58. The method comprises the following steps: adding an organic boron and guanidine / phosphazene base combined catalyst, epoxide and anhydride into a reaction container under anhydrous and anaerobic conditions, reacting for a certain time at a specific temperature, diluting the obtained mixture with dichloromethane, slowly dropwise adding into excessive ethanol to precipitate a polymer, and filtering and drying to obtain the high molecular weight polyester. The method can be used for synthesizing high-molecular-weight polyester, and has a good application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester synthesis catalysis, and in particular to the application of an organic boron and guanidine / phosphazene base combined catalyst and a high molecular weight polyester synthesis method. Background Art

[0002] While the innovative application of polymer materials is driving social progress, their recalcitrant nature has also led to increasingly severe environmental problems. Against this backdrop, the development of biodegradable polymer materials that combine low cost and high performance has become a key approach to addressing this issue and has rapidly become a research hotspot of concern to both academia and industry. Among these, polyester materials, due to the easily hydrolyzed ester bonds in their backbone, exhibit excellent biodegradability potential and are widely used in fiber products, plastics, medical devices, and other fields. Therefore, the development of new biodegradable polyester materials based on inexpensive monomers has significant application value.

[0003] Styrene oxide and vinyl ethylene oxide are two important types of epoxy monomers that can be prepared by epoxidation of cheap olefin raw materials styrene and butadiene. These monomers are subjected to controllable ring-opening copolymerization with rigid phthalic anhydride, and it is expected to produce polyester materials with both economic benefits and excellent performance. In the polyester synthesis process, the rational design of catalysts is the key to increasing molecular weight and improving material properties. However, these two epoxy monomers have serious structural instability problems during the polymerization process and are prone to isomerization side reactions. This phenomenon seriously restricts the increase in the molecular weight of polyester products. Taking the research of Lu Xiaobing's research group in 2019 as an example, even with the use of binuclear aluminum catalysts and the reaction under mild conditions, the number average molecular weight of the copolymerization product of styrene oxide and phthalic anhydride is still limited to less than 18,300 (J.Am.Chem.Soc.2019,141,8937-8942).

[0004] In recent years, organic catalysts have gradually been favored by researchers due to their advantage of no metal residues. In 2024, the Chinese patent document CN118240194A innovatively adopted a (thio)urea / phosphazene base catalytic system to successfully achieve the synthesis of high molecular weight polyesters with a number average molecular weight of 50,900 to 76,700. However, this system still has obvious limitations: on the one hand, the polymerization rate is slow, and on the other hand, the molecular weight distribution of the obtained product is wide. More noteworthy is that this catalytic system is completely unsuitable for vinyl ethylene oxide monomers.

[0005] Based on the above research status, the development of a novel organic catalytic system to achieve efficient and controlled copolymerization of styrene oxide / vinyl ethylene oxide with phthalic anhydride, and thereby synthesize high molecular weight, narrowly distributed polyester materials, is not only of great scientific significance but also has significant application value. Breakthroughs in this research direction will provide new technical support for the industrial application of biodegradable polymer materials. Summary of the Invention

[0006] In order to achieve efficient and controllable copolymerization of styrene oxide / vinyl ethylene oxide and phthalic anhydride, and then synthesize high molecular weight, narrow distribution polyester materials, the present invention proposes the use of an organic boron and guanidine / phosphazene base combined catalyst and a high molecular weight polyester synthesis method.

[0007] The technical solutions of the present invention are as follows:

[0008] An application of a combined catalyst of organoboron and guanidine / phosphazene base for the synthesis of high molecular weight polyesters;

[0009] The high molecular weight polyester has a number average molecular weight of 50,200 to 163,300 and a molecular weight distribution of 1.22 to 1.58;

[0010] The structural formula of the organic boron is one of B1 to B5 shown below:

[0011]

[0012] The structural formula of the guanidine is one of G1 to G5 shown below:

[0013] The structural formula of the phosphazene base is one of P1 to P4 shown below:

[0014] Preferably, the structural formula of the organoboron is:

[0015]

[0016] The structural formula of the guanidine is:

[0017]

[0018] The structural formula of the phosphazene base is:

[0019]

[0020] The present invention also provides a method for synthesizing high molecular weight polyester, which specifically comprises the following steps:

[0021] S1. Under anhydrous and oxygen-free conditions, the above-mentioned organoboron and guanidine / phosphazene base combination catalyst, epoxide and acid anhydride are added to a reaction vessel and reacted at a specific temperature for a certain time;

[0022] S2. After the reaction is completed, the obtained mixture is diluted with dichloromethane, and then slowly added dropwise to excess ethanol to precipitate a polymer, which is then filtered and dried to obtain a high molecular weight polyester.

[0023] Preferably, the epoxide is styrene oxide or vinyl ethylene oxide.

[0024] Preferably, the acid anhydride is phthalic anhydride.

[0025] Preferably, the molar ratio of the acid anhydride, epoxide, organic boron and guanidine / phosphazene base is 1000:1200-2500:0.5-2:1-14.

[0026] Preferably, the specific temperature is 25° C. to 120° C., and the reaction time is 1 h to 150 h.

[0027] Preferably, the drying time is 24 hours to 48 hours, and the drying temperature is 30° C. to 80° C.

[0028] The present invention also provides a high molecular weight polyester prepared by the above synthesis method.

[0029] Compared with the prior art, the present invention has the following specific beneficial effects:

[0030] 1. Compared to traditional (thio)urea / phosphazene base catalysts, the organoboron-guanidine / phosphazene base composite catalytic system developed in this paper combines both initiation and catalysis functions, effectively promoting the ring-opening copolymerization of styrene oxide / vinyl ethylene oxide with phthalic anhydride. This system not only significantly improves polymerization efficiency but also achieves a significant increase in molecular weight (up to 163,300) and precise control of molecular weight distribution (down to 1.22), providing key guarantees for the mechanical and processing properties of polyester materials.

[0031] 2. Compared to traditional metal catalysts, the organic catalytic system of this invention effectively suppresses the isomerization side reaction of epoxy monomers, resolving the structural instability issue during polymerization. Furthermore, the system is completely metal-free, completely avoiding the adverse effects of metal residues in the product on material properties such as biocompatibility and thermal stability, potentially enabling future applications in polyesters. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of the polyester synthesized in Example 5;

[0033] Figure 2is a gel permeation chromatogram of the polyester synthesized in Example 5;

[0034] Figure 3 is the hydrogen nuclear magnetic resonance spectrum of the polyester synthesized in Example 18;

[0035] Figure 4 This is the gel permeation chromatogram of the polyester synthesized in Example 18. DETAILED DESCRIPTION

[0036] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the specification of the present invention. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as limiting the present invention.

[0037] It should be noted that the present invention has no particular restrictions on the sources of the styrene oxide, vinyl ethylene oxide, and phthalic anhydride; commercially available products may be used. The present invention preferably purifies the commercially available styrene oxide, vinyl ethylene oxide, and phthalic anhydride before carrying out the polymerization reaction. In the present invention, styrene oxide and vinyl ethylene oxide serve as both reactive monomers and solvents for dissolving the monomers and polymers. The present invention has no particular restrictions on the purification methods of the styrene oxide, vinyl ethylene oxide, and phthalic anhydride; distillation and recrystallization techniques well known to those skilled in the art may be employed. The present invention has no particular restrictions on the amount of dichloromethane used; it may be sufficient to fully dissolve the resulting polymerization mixture; the present invention has no particular restrictions on the amount of ethanol used; it may be sufficient to precipitate the diluted polymerization mixture at a high yield; and the filtration and drying methods have no particular restrictions; it may be sufficient to employ filtration and drying techniques well known to those skilled in the art.

[0038] Example 1.

[0039] Under anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1 (0.1 mmol), organoboron B1 (0.02 mmol) and styrene oxide (18 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 18 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 h. 1 H NMR analysis showed that the conversion of phthalic anhydride was 99%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.58 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 85,000, with a molecular weight distribution of 1.34.

[0040] The above-mentioned organic boron B1 was replaced with an equal molar amount of B2, and the rest remained unchanged. The conversion rate was 95%, and 2.34 g of polymer was precipitated, with a number average molecular weight of 70,200 and a molecular weight distribution of 1.31.

[0041] The above-mentioned organic boron B1 was replaced with an equal molar amount of B3, and the rest remained unchanged. The conversion rate was 99%, and 2.48 g of polymer was precipitated, with a number average molecular weight of 81,200 and a molecular weight distribution of 1.38.

[0042] The above-mentioned organic boron B1 was replaced with an equal molar amount of B4, and the rest remained unchanged. The conversion rate was 85%, and 2.11 g of polymer was precipitated, with a number average molecular weight of 65,900 and a molecular weight distribution of 1.41.

[0043] The above-mentioned organic boron B1 was replaced with an equal molar amount of B5, and the rest remained unchanged. The conversion rate was 99%, and 2.52 g of polymer was precipitated, with a number average molecular weight of 52,700 and a molecular weight distribution of 1.51.

[0044] Example 2.

[0045] Under anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.1 mmol), organoboron B1 (0.02 mmol) and styrene oxide (18 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 21 hours. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 hours. 1 H NMR analysis showed that the conversion of phthalic anhydride was 99%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.60 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 158,400, with a molecular weight distribution of 1.26.

[0046] Example 3.

[0047] Under anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P2 (0.1 mmol), organoboron B1 (0.02 mmol) and styrene oxide (18 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 18 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 h. 1 H NMR analysis showed that the conversion of phthalic anhydride was 99%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.52 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 51,700, with a molecular weight distribution of 1.56.

[0048] Example 4.

[0049] Under anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P4 (0.05 mmol), organoboron B1 (0.02 mmol) and styrene oxide (18 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 16 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 h. 1 H NMR analysis showed that the conversion of phthalic anhydride was 99%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.55 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 57,800, with a molecular weight distribution of 1.58.

[0050] Example 5.

[0051] Under anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.1 mmol), organoboron B1 (0.01 mmol) and styrene oxide (18 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 28 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 24 h. 1 H NMR analysis showed that the conversion of phthalic anhydride was 86%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.19 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 163,300, with a molecular weight distribution of 1.27.

[0052] Example 6.

[0053] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.1 mmol), organoboron B1 (0.005 mmol) and styrene oxide (18 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 56 hours. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for filtration. 1 H NMR analysis showed that the conversion of phthalic anhydride was 89%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.23 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 105,200, with a molecular weight distribution of 1.29.

[0054] Example 7.

[0055] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.1 mmol), organoboron B1 (0.01 mmol) and styrene oxide (18 mmol) were added to the reaction flask. The reaction was carried out at 50°C for 48 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 h.1 H NMR analysis showed a phthalic anhydride conversion of 92%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.32 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 141,500, with a molecular weight distribution of 1.22.

[0056] Example 8.

[0057] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.1 mmol), organoboron B1 (0.02 mmol) and styrene oxide (18 mmol) were added to the reaction flask. The reaction was carried out at 80°C for 5.5 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for filtration. 1 H NMR analysis showed a phthalic anhydride conversion of 87%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.19 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 68,500, with a molecular weight distribution of 1.24.

[0058] The amount of the phosphazene base P1' was changed from 0.1 mmol to 0.04 mmol, and the reaction was continued for 3 h. The other parameters remained unchanged, and the conversion rate was 40%. 0.99 g of polymer was precipitated, with a number average molecular weight of 51,200 and a molecular weight distribution of 1.31.

[0059] The amount of the phosphazene base P1' was changed from 0.1 mmol to 0.06 mmol, and the reaction was continued for 4 h. The other parameters remained unchanged, and the conversion rate was 45%. 1.21 g of polymer was precipitated, with a number average molecular weight of 52,500 and a molecular weight distribution of 1.35.

[0060] The amount of the phosphazene base P1' was changed from 0.1 mmol to 0.08 mmol, and the reaction was continued for 7 h. The other conditions remained unchanged, and the conversion rate was 91%. 2.34 g of polymer was precipitated, with a number average molecular weight of 50,200 and a molecular weight distribution of 1.38.

[0061] The amount of the phosphazene base P1' was changed from 0.1 mmol to 0.14 mmol, and the reaction was continued for 5 h. The conversion rate was 92%, and 2.36 g of polymer was precipitated. The number average molecular weight was 63,800 and the molecular weight distribution was 1.24.

[0062] Example 9.

[0063] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), guanidine G3 (0.1 mmol), organoboron B1 (0.02 mmol) and styrene oxide (18 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 22 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 h. 1 H NMR analysis showed that the conversion of phthalic anhydride was 99%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.46 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 97,600, with a molecular weight distribution of 1.37.

[0064] The above guanidine G3 was replaced with an equal molar amount of guanidine G1, and the rest remained unchanged. The conversion rate was 99%, and 2.49 g of polymer was precipitated, with a number average molecular weight of 62,600 and a molecular weight distribution of 1.41.

[0065] The above guanidine G3 was replaced with an equal molar amount of guanidine G2, and the rest remained unchanged. The conversion rate was 99%, and 2.57 g of polymer was precipitated, with a number average molecular weight of 72,800 and a molecular weight distribution of 1.54.

[0066] The above guanidine G3 was replaced with an equal molar amount of guanidine G4, and the rest remained unchanged. The conversion rate was 99%, and 2.54 g of polymer was precipitated, with a number average molecular weight of 57,000 and a molecular weight distribution of 1.52.

[0067] The above guanidine G3 was replaced with an equal molar amount of guanidine G5, and the rest remained unchanged. The conversion rate was 99%, and 2.56 g of polymer was precipitated, with a number average molecular weight of 51,600 and a molecular weight distribution of 1.43.

[0068] Example 10.

[0069] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), guanidine G1 (0.05 mmol), organoboron B1 (0.01 mmol) and vinyl oxirane (24 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 29 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for filtration. 1 HNMR analysis showed that the conversion of phthalic anhydride was 92%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.89 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 64,200, and the molecular weight distribution was 1.41.

[0070] The amount of the above guanidine G1 was changed from 0.05 mmol to 0.025 mmol, and the reaction was carried out for 48 h. The other parameters remained unchanged, and the conversion rate was 96%. 1.96 g of polymer was precipitated, with a number average molecular weight of 67,000 and a molecular weight distribution of 1.38.

[0071] The amount of the above guanidine G1 was changed from 0.05 mmol to 0.015 mmol, and the reaction was carried out for 69 h. The other parameters remained unchanged, and the conversion rate was 90%. 1.82 g of polymer was precipitated, with a number average molecular weight of 58,300 and a molecular weight distribution of 1.45.

[0072] The amount of the above guanidine G1 was changed from 0.05 mmol to 0.01 mmol, and the reaction was carried out for 114 h. The other parameters remained unchanged, and the conversion rate was 85%. 1.73 g of polymer was precipitated, with a number average molecular weight of 50,600 and a molecular weight distribution of 1.54.

[0073] Example 11.

[0074] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), guanidine G2 (0.025 mmol), organoboron B1 (0.01 mmol) and vinyl oxirane (24 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 48 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 h. 1 HNMR analysis showed that the conversion of phthalic anhydride was 89%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.80 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 69,100, and the molecular weight distribution was 1.36.

[0075] The above guanidine G2 was replaced with an equal molar amount of guanidine G3, and the rest remained unchanged. The conversion rate was 85%, and 1.72 g of polymer was precipitated, with a number average molecular weight of 75,300 and a molecular weight distribution of 1.35.

[0076] The above guanidine G2 was replaced with an equal molar amount of guanidine G4, and the rest remained unchanged. The conversion rate was 97%, and 2.01 g of polymer was precipitated, with a number average molecular weight of 58,100 and a molecular weight distribution of 1.48.

[0077] The above guanidine G2 was replaced with an equal molar amount of guanidine G5, and the rest remained unchanged. The conversion rate was 99%, and 2.05 g of polymer was precipitated. The number average molecular weight was 50,400 and the molecular weight distribution was 1.36.

[0078] Example 12.

[0079] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.025 mmol), organoboron B1 (0.01 mmol) and vinyl oxirane (24 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 36 hours. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for filtration. 1HNMR analysis showed that the conversion of phthalic anhydride was 90%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.84 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 64,300, and the molecular weight distribution was 1.47.

[0080] Example 13.

[0081] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.035 mmol), organoboron B1 (0.01 mmol) and vinyl oxirane (24 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 36 hours. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for filtration. 1 HNMR analysis showed that the conversion of phthalic anhydride was 99%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.95 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 54,100, and the molecular weight distribution was 1.35.

[0082] Example 14.

[0083] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.035 mmol), organoboron B1 (0.015 mmol) and vinyl oxirane (24 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 27 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 24 h. 1 HNMR analysis showed that the conversion of phthalic anhydride was 99%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.97 g of polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 65,800, and the molecular weight distribution was 1.41.

[0084] Example 15.

[0085] Under anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.035 mmol), organoboron B1 (0.015 mmol) and vinyl oxirane (18 mmol) were added to the reaction flask. The reaction was carried out at 60°C for 24 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 24 h. 1 HNMR analysis showed that the conversion of phthalic anhydride was 99%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 2.02 g of polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 71,000, and the molecular weight distribution was 1.49.

[0086] Example 16.

[0087] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.035 mmol), organoboron B1 (0.015 mmol) and vinyl oxirane (18 mmol) were added to the reaction flask. The reaction was carried out at 50°C for 46 hours. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for filtration. 1 HNMR analysis showed that the conversion of phthalic anhydride was 99%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.93 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 80,300, and the molecular weight distribution was 1.41.

[0088] Example 17.

[0089] Under anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.035 mmol), organoboron B1 (0.015 mmol) and vinyl oxirane (14 mmol) were added to the reaction flask. The reaction was carried out at 50°C for 42 hours. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for filtration. 1 HNMR analysis showed that the conversion of phthalic anhydride was 88%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.75 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 87,200, and the molecular weight distribution was 1.40.

[0090] Example 18.

[0091] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.035 mmol), organoboron B1 (0.015 mmol) and vinyl oxirane (14 mmol) were added to the reaction flask. The reaction was carried out at 40°C for 65 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 h. 1 HNMR analysis showed that the conversion of phthalic anhydride was 82%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.68 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 105,100, and the molecular weight distribution was 1.50.

[0092] Example 19.

[0093] In anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1' (0.035 mmol), organoboron B5 (0.015 mmol) and vinyl oxirane (14 mmol) were added to the reaction flask. The reaction was carried out at 40°C for 65 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 h. 1 HNMR analysis showed that the conversion of phthalic anhydride was 90%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.87 g of polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 61,200, and the molecular weight distribution was 1.45.

[0094] Example 20.

[0095] Under anhydrous and oxygen-free conditions, phthalic anhydride (10 mmol), phosphazene base P1 (0.035 mmol), organoboron B1 (0.015 mmol) and vinyl oxirane (14 mmol) were added to the reaction flask. The reaction was carried out at 40°C for 65 h. 5 mL of dichloromethane was added to dilute the mixture, and about 0.2 mL of the mixed solution was taken for 2 h. 1 HNMR analysis showed that the conversion of phthalic anhydride was 84%. The reaction mixture was precipitated with 100 mL of ethanol to obtain 1.70 g of a polymer. The polymer obtained in this example was analyzed by gel permeation chromatography using polystyrene as a standard, and the number average molecular weight of the copolymer was 78,300, and the molecular weight distribution was 1.48.

[0096] As can be seen from the above examples, the present invention uses organoboron and guanidine / phosphazene base as catalysts to overcome the problem of easy isomerization of styrene oxide / vinyl ethylene oxide during the polymerization process, and successfully realizes the synthesis of high molecular weight polyester based on inexpensive monomers styrene oxide / vinyl ethylene oxide and phthalic anhydride.

[0097] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. An application of an organic boron and guanidine / phosphazene base combined catalyst, characterized in that: Used to synthesize high molecular weight polyester; The high molecular weight polyester has a number average molecular weight of 50,200 to 163,300 and a molecular weight distribution of 1.22 to 1.58; The structural formula of the organic boron is one of B1 to B5 shown below: The structural formula of the guanidine is one of G1 to G5 shown below: The structural formula of the phosphazene base is one of P1 to P4 shown below:

2. The use of the organoboron and guanidine / phosphazene base combined catalyst according to claim 1, characterized in that: The structural formula of the organoboron is: The structural formula of the guanidine is: The structural formula of the phosphazene base is:

3. A method for synthesizing high molecular weight polyester, characterized in that: The steps include: S1. Under anhydrous and oxygen-free conditions, adding an organic boron and guanidine / phosphazene base combined catalyst, epoxide and acid anhydride to a reaction vessel, and reacting at a specific temperature for a certain time; S2. After the reaction is completed, the obtained mixture is diluted with dichloromethane, and then slowly added dropwise to excess ethanol to precipitate a polymer, which is then filtered and dried to obtain a high molecular weight polyester.

4. The method for synthesizing high molecular weight polyester according to claim 3, wherein: The epoxide is styrene oxide or vinyl ethylene oxide.

5. The method for synthesizing high molecular weight polyester according to claim 3, wherein: The acid anhydride is phthalic anhydride.

6. The method for synthesizing high molecular weight polyester according to claim 3, wherein: The molar ratio of the acid anhydride, epoxide, organic boron and guanidine / phosphazene base is 1000:1200-2500:0.5-2:1-14.

7. The method for synthesizing high molecular weight polyester according to claim 3, wherein: The specific temperature is 25° C. to 120° C., and the reaction time is 1 hour to 150 hours.

8. The method for synthesizing high molecular weight polyester according to claim 5, wherein: The drying time is 24 hours to 48 hours, and the drying temperature is 30° C. to 80° C.

9. A high molecular weight polyester prepared by the synthesis method according to any one of claims 3 to 8.

Images