A process for the preparation of polyoxalates from a cyclic oxalate monomer and its cyclic oligomers by ring-opening polymerization

Abstract

The method for preparing polyoxalate by ring-opening polymerization of cyclic oxalate monomers and cyclic oligomers thereof disclosed by the application is that at least one of the cyclic oxalate monomers and the cyclic oligomers thereof, or a blend of at least one of the cyclic oxalate monomers and the cyclic oligomers thereof and at least one of cyclic lactone, cyclic lactide and cyclic carbonate, is subjected to bulk ring-opening polymerization or solution ring-opening polymerization under the action of a catalyst and an initiator to obtain polyoxalate and its copolymer. Since the application adopts ring-opening polymerization to prepare polyoxalate, not only the problems of low esterification polycondensation efficiency and poor polymerization controllability are avoided, but also the side reactions of alpha-keto acid decarboxylation and terminal hydroxyl group etherification in the esterification polycondensation process are avoided, so that the polyoxalate obtained has controllable polymerization degree / molecular weight, high structural regularity and clear end group structure, and further has higher melting point and crystallization temperature and is white, and at the same time, a new way for preparing polyoxalate is provided.

Description

Technical Field

[0001] This invention belongs to the field of polyester material preparation technology, specifically relating to a method for preparing polyoxalate by ring-opening polymerization of cyclooxalate monomer and its cyclic oligomer. Background Technology

[0002] Polymer materials are widely used in various aspects of the national economy due to their advantages such as light weight, good processability, low cost, and stability. However, the high chemical stability and long decomposition cycle of traditional polymer materials have led to environmental pollution and hazards caused by the large-scale use of their products, continuous accumulation of waste, and significant leakage, which has attracted great attention from society. Developing and using biodegradable plastics is one of the effective ways to solve this problem.

[0003] Currently, the market mainly offers a limited number of biodegradable materials, including polylactic acid (PLA), polybutylene terephthalate (PET), polybutylene succinate (PSS), and polyglycolic acid (PEG). Considering factors such as environmental degradation performance, mechanical properties, thermal properties, and economic viability, these commercially available biodegradable materials still have shortcomings. For example, PLA and PET require composting for degradation, which not only limits their degradation methods but also results in slow degradation in the natural environment. PEG, due to its high melting point, has a narrow processing window, restricting its application range.

[0004] Polyoxalates, due to their high ester bond density, typically possess high melting points and mechanical strength. Polyethylene oxalate (PEG) is the most representative variety, with a melting point of 175℃ and tensile strength of 76 MPa, comparable to polylactic acid (PLA). Furthermore, PEG can biodegrade naturally in aquatic environments, eliminating the need for industrial composting conditions required for PLA (Macromolecules 2023, 56, 3149-3159). Since oxalic acid and ethylene glycol are the cheapest organic diacid and diol, respectively, the raw materials for PEG are extremely cost-effective. If green, efficient, and controllable synthesis can be achieved, its price could potentially be only half that of PLA. Moreover, PEG materials have shown considerable application potential in biodegradable agricultural films (CN115584107A), seawater-degradable films (CN 116836522A), and the oil extraction field (CN 106029732A).

[0005] To date, polyoxalate has been produced by esterification polycondensation of oxalic acid or oxalate with diols, which usually requires melt polycondensation under high temperature and reduced pressure. This method requires prolonged high temperature and produces side reactions such as α-keto acid decarboxylation and back-biting depolymerization, resulting in problems such as reduced polymer molecular weight and yellowing color. There are two existing technical means to solve the above problems: (1) preparing highly efficient catalysts, such as CN 115466378A and CN 117964889A, which respectively use titanium-aluminum composite catalyst and organotin and rare earth compound composite catalyst to obtain high molecular weight polyoxalate; (2) changing melt polycondensation to solid-phase polycondensation, such as CN 103788325A and CN 102718948A, which obtain light-colored high molecular weight polyoxalate by reducing the reaction temperature and solid-phase thickening. However, regardless of the specific technique used, both are improvements to the esterification polycondensation preparation method and cannot overcome the problems of low esterification polycondensation efficiency and poor polymerization controllability. Furthermore, due to the high-temperature etherification side reaction of the diol, the polyoxalate molecular chain obtained by esterification polycondensation contains etherification units and has poor structural regularity (Macromolecules 2023, 56, 3149-3159). Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing melt polycondensation methods for preparing polyoxalates by providing a method for preparing polyoxalates through ring-opening polymerization of cyclooxalate monomers and their cyclic oligomers.

[0007] This invention provides a method for preparing polyoxalate by ring-opening polymerization of cyclooxalate monomers and their cyclic oligomers. The method involves bulk ring-opening polymerization of at least one of cyclic oxalate monomers and their cyclic oligomers, or a blend of at least one of cyclic oxalate monomers and their cyclic oligomers with at least one of cyclic lactones, cyclic lactones, and cyclic carbonates, under the action of a catalyst and an initiator, to obtain polyoxalate and copolymers of the following general structural formulas; or solution ring-opening polymerization to obtain polyoxalate and copolymers of the following general structural formulas:

[0008]

[0009] In the formula, R1 is any group.

[0010] In the above method, the molar ratio of catalyst to cyclic oxalate monomer and its cyclic oligomer in the bulk ring-opening polymerization reaction is 1 / 20000 to 1 / 100, preferably 1 / 10000 to 1 / 2000; the molar ratio of initiator to cyclic oxalate monomer and its cyclic oligomer is 1 / 10000 to 1 / 20, preferably 1 / 5000 to 1 / 200; the reaction temperature is 60 to 240°C, preferably 120 to 200°C; and the reaction time is 0.1 to 48 hours, preferably 0.5 to 12 hours.

[0011] In the above method, the concentration of the reaction solution prepared from the cyclic oxalate monomer and its cyclic oligomer in the solution ring-opening polymerization reaction is 0.1–3 mol·L⁻¹. -1 Preferably 0.2–2 mol·L -1 The molar ratio of catalyst to cyclic oxalate monomer and its cyclic oligomer is 1 / 10000 to 1 / 50, preferably 1 / 5000 to 1 / 100; the molar ratio of initiator to cyclic oxalate monomer and its cyclic oligomer is 1 / 10000 to 1 / 20, preferably 1 / 5000 to 1 / 200; the reaction temperature is room temperature to 200°C, preferably room temperature to 120°C; the reaction time is 0.1 to 48 hours, preferably 0.5 to 12 hours.

[0012] The solvent used to prepare the solution in the solution ring-opening polymerization reaction described above is any one of toluene, chloroform, tetrahydrofuran, dimethyl sulfoxide, or γ-valerolactone.

[0013] The cyclic oxalate monomers and their cyclic oligomers described in the above methods are based on CN 114805776A / WO.

[0014] The preparation was carried out using the method disclosed in 2023231524, and purified to gas phase purity by recrystallization and / or melt-crystallization.

[0015] Polyoxalate with a content of ≥98% has the following general structural formula:

[0016]

[0017] In the formula, R1 is any group.

[0018] The cyclic oxalate monomers described in the above methods are preferably 6- to 10-membered ring monomers, and the structures are further preferred as follows:

[0019]

[0020] The cyclic oxalate oligomers described in the above methods are cyclic dimers, preferably dimers with 12 to 20 membered rings, and the structures are further preferred as follows:

[0021]

[0022] In the above methods, R1 in the general formula of polyoxalate and its copolymers is preferably a group with 2 to 6 main chain atoms.

[0023] The following are further preferred structures of polyoxalate and its copolymers:

[0024]

[0025] The cyclic lactones, cyclic lactides, and cyclic carbonates mentioned in the above methods are preferably lactide, glycolide, caprolactone, p-dioxanone, and cyclotrimethylene carbonate.

[0026] The catalyst described in the above methods is at least one of stannous catalysts, organobismuth catalysts, organotitanium catalysts, and organic acid catalysts. Preferably, it is at least one of stannous octoate, stannous chloride, stannous stearate, stannous benzoate, bismuth basic salicylate, triphenylbismuth, bismuth stearate, tetrabutyl titanate, tetraisopropyl titanate, diphenyl phosphate, dodecylbenzenesulfonic acid, and p-toluenesulfonic acid.

[0027] The initiator described in the above methods is a trace amount of water and / or at least one of primary alcohols, secondary alcohols, primary amines, and secondary amines contained in the cyclic oxalate monomer and its cyclic oligomer. Preferred primary alcohols, secondary alcohols, primary amines, and secondary amines are at least one of benzyl alcohol, ethylene glycol, neopentyl glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, ethyl lactate, lauryl alcohol, octadecyl alcohol, octadecylamine, 1,6-hexanediamine, and ethanolamine.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1. Because this invention takes a different approach by using cyclic oxalate monomers and their cyclic oligomers as raw materials, the reaction for preparing polyoxalate is changed from the existing esterification polycondensation reaction to a ring-opening polymerization reaction. This not only avoids the problems of low efficiency and poor controllability of esterification polycondensation, but also provides a new route for the preparation of polyoxalate.

[0030] 2. Since the preparation method provided by the present invention uses cyclic oxalate monomers and their cyclic oligomers as reaction raw materials, and prepares polyoxalate through ring-opening polymerization with good and controllable activity, the side reactions of α-keto acid decarboxylation and terminal hydroxyl etherification in the esterification polycondensation process can be avoided, so that the degree of polymerization / molecular weight of the obtained polyoxalate is controllable, the structural regularity is high, and the end group structure is clear, thereby obtaining polyoxalate with higher melting point and crystallization temperature.

[0031] 3. Because the preparation method provided by this invention has a fast polymerization reaction rate and short polymerization time, the ring-opening polymerization process does not have a large number of terminal carboxyl intermediates and does not require a long-term high-temperature reaction, thus avoiding the problem of yellowing and blackening of the polymerization product caused by side reactions such as α-keto acid decarboxylation. In this way, white polyoxalate can be obtained, which can expand its application range.

[0032] 4. Because the preparation process of the method provided by the present invention is simple and energy-efficient, it is easy to promote and apply. Attached Figure Description

[0033] Figure 1This is a digital photograph of the polymer prepared in Example 1 of the present invention. The photograph shows that the polyoxalate prepared using the method of the present invention is white.

[0034] Figure 2 The image shows the 1H NMR spectrum of the polyoxalate prepared in Example 3 of this invention. The spectrum shows solvent peaks at 4.2 and 5.3 ppm, a water peak at 2.7 ppm, and a repeating unit peak of the polyoxalate at 4.4 ppm. The absence of etherified structural units indicates that the polymer was not only successfully prepared but also exhibits high molecular weight and structural regularity.

[0035] Figure 3 The figure shows the DSC single-heat curve of the polyoxalate prepared in Example 5 of this invention. It can be seen from the figure that the prepared polymer has two crystal forms with melting points of 174 and 182 °C, respectively, which are higher than the melting points of the two crystal forms of polyoxalate obtained by esterification polycondensation (the melting points reported in Macromolecules 2023, 56, 3149-3159 are 168 and 175 °C, respectively). This also indirectly indicates that the polyoxalate prepared by ring-opening polymerization has higher structural regularity.

[0036] Figure 4 The figure shows the DSC cooling curve of the polyoxalate prepared in Example 5 of this invention. As can be seen from the figure, the crystallization temperature of the prepared polymer is 152°C, which is higher than the crystallization temperature of the polyoxalate obtained by esterification polycondensation (Macromolecules 2023, 56, 3149-3159 reported a crystallization temperature of 141°C). This also indicates that the polyoxalate prepared by ring-opening polymerization has higher structural regularity.

[0037] Figure 5 The image shows the MALDI-TOF MS spectrum of the polyoxalate prepared in Example 2 of this invention. The peak spacing and end-group fitting indicate that the polyoxalate synthesized by ring-opening polymerization has high structural regularity and well-defined end-group structures (initiated by benzyl alcohol, with benzyloxy and hydroxyl groups at the two ends of the polymer chain, respectively).

[0038] Figure 6 This is a digital photograph of the polymer prepared in Example 9 of the present invention. The photograph shows that the polyoxalate prepared using the method of the present invention is white.

[0039] Figure 7 The image shows the 1H NMR spectrum of the polyoxalate prepared in Example 12 of this invention. The spectrum shows a water peak at 1.6 ppm, a solvent peak at 7.2 ppm, and peaks at 4.4 and 2.2 ppm representing repeating units of the polyoxalate. The absence of etherified structural units indicates that the polymer was not only successfully prepared but also exhibits high molecular weight and structural regularity.

[0040] Figure 8The figure shows the DSC single-heat curve of the polyoxalate prepared in Example 14 of the present invention. It can be seen from the figure that the melting points of the prepared polymers are 46 and 74 °C, respectively.

[0041] Figure 9 The figure shows the DSC cooling curve of the polyoxalate prepared in Example 14 of this invention. It can be seen from the figure that no crystallization peak was observed in the prepared polymer under the test condition of 10℃ / min.

[0042] Figure 10 The MALDI-TOF MS spectrum of the polyoxalate prepared in Example 10 of this invention. The peak spacing and end-group fitting can be seen from the figure, indicating that the polyoxalate synthesized by ring-opening polymerization has high structural regularity and well-defined end-group structure (initiated by benzyl alcohol, with benzyloxy and hydroxyl groups at the two ends of the polymer molecular chain, respectively).

[0043] Figure 11 This is a digital photograph of the polymer prepared in Example 15 of the present invention. The photograph shows that the polyoxalate prepared by the method of the present invention is white in color.

[0044] Figure 12 The image shows the 1H NMR spectrum of the polyoxalate prepared in Example 17 of this invention. The spectrum shows a water peak at 1.6 ppm, a solvent peak at 7.2 ppm, and peaks at 4.2 and 1.2 ppm representing repeating units of the polyoxalate. The absence of etherified structural units indicates that the polymer was not only successfully prepared but also exhibits high molecular weight and structural regularity.

[0045] Figure 13 The figure shows the DSC temperature rise curve of the polyoxalate prepared in Embodiment 19 of the present invention. It can be seen from the figure that the melting point of the prepared polymer is 105℃.

[0046] Figure 14 The figure shows the DSC cooling curve of the polyoxalate prepared in Embodiment 19 of this invention. It can be seen from the figure that no crystallization peak was observed in the prepared polymer under the test condition of 10℃ / min.

[0047] Figure 15 The image shows the MALDI-TOF MS spectrum of the polyoxalate prepared in Example 16 of this invention. The peak spacing and end-group fitting are visible in the image, indicating that the polyoxalate synthesized by ring-opening polymerization has high structural regularity and well-defined end-group structures (initiated by benzyl alcohol, with benzyloxy and hydroxyl groups at the two ends of the polymer chain, respectively). Detailed Implementation

[0048] The following embodiments are provided to further illustrate the present invention in detail. However, the following embodiments should not be construed as limiting the scope of protection of the present invention. If those skilled in the art make some non-essential improvements and adjustments to the present invention based on the content of the present invention, they shall still fall within the scope of protection of the present invention.

[0049] It is worth noting that the test conditions for the relevant performance parameters of the polyoxalate obtained in the following examples are as follows:

[0050] 1) Determination of intrinsic viscosity: The intrinsic viscosity was measured by the Ubbelohde viscometer method at 25°C. In Examples 1-9, the solvent was hexafluoroisopropanol and the Ubbelohde viscometer tube diameter was 0.5-0.6 mm. In Examples 10-75, the solvent was dichloromethane and the Ubbelohde viscometer tube diameter was 0.3-0.4 mm.

[0051] 2) Proton NMR spectroscopy: Deuterated hexafluoroisopropanol or deuterated chloroform are used as solvents.

[0052] 3) DSC test: N2 flow rate 20 mL / min, starting from -40℃, increase the temperature to 200℃ at 10℃ / min, hold at 200℃ for 3 min, then decrease the temperature to -40℃ at 10℃ / min, then increase the temperature to 200℃ at 10℃ / min, and finally equilibrate to 25℃.

[0053] 4) MALDI-TOF MS test: Using hexafluoroisopropanol or dichloromethane as solvent, the polymer was prepared into a solution with a concentration of 0.1-0.2 mg / mL, and soft ionization mass spectrometry was performed using CHCA / DMAP as the matrix.

[0054] 5) Yield calculation: Yield (%) = W / W0*100%, where W is the mass of the polymer after purification and drying, and W0 is the mass of the monomers fed into the reaction.

[0055] Example 1

[0056] 5.80 g (50.0 mmol) of cyclooxalate monomer A1 was placed in a dry polymerization flask, and 1.00 mg (0.0025 mmol) of stannous octoate catalyst was added. The reaction was initiated using trace amounts of water in the reaction system without the addition of an additional initiator. The reaction was carried out at 190 °C for 1.5 h under a nitrogen atmosphere. After the reaction was completed, the resulting pulverized / crushed polymerization product was extracted with dichloromethane and then vacuum dried to remove the solvent, finally yielding 5.68 g of product C1 (yield 98.0%). The intrinsic viscosity of this product was tested to be 3.24 dL / g. The product is white in color, as seen in the attached image. Figure 1 .

[0057] Example 2

[0058] 5.80 g (50.0 mmol) of cyclooxalate monomer A1 was placed in a dry polymerization flask, and 2.70 mg (0.025 mmol) of benzyl alcohol and 1.80 mg (0.0005 mmol) of basic bismuth salicylate catalyst were added. The reaction was carried out at 200 °C for 0.1 h. After the reaction was completed, the polymerization product was pulverized / crushed and the residual monomer / volatiles were removed by vacuum distillation to finally obtain 5.67 g of product C1 (yield 97.8%). The intrinsic viscosity of the product was tested to be 1.32 dL / g. The MALDI-TOF MS spectrum is shown in [reference needed]. Figure 5 .

[0059] Example 3

[0060] 5.80 g (50.0 mmol) of cyclooxalate monomer A1 was placed in a dry polymerization flask and placed in an oil bath at 150 °C under an argon atmosphere. After the monomer melted, 3.20 mg (0.05 mmol) of ethylene glycol and 9.00 mg (0.025 mmol) of stannous benzoate catalyst were added. The reaction was carried out at 200 °C for 5 h. After the reaction was completed, the obtained pulverized / crushed polymerization product was extracted with dichloromethane and then vacuum dried to remove the solvent, finally yielding 5.70 g of product C1 (yield 98.3%). The intrinsic viscosity of the product was tested to be 1.12 dL / g. The 1H NMR spectrum is shown in the appendix. Figure 2 .

[0061] Example 4

[0062] 5.80 g (25.0 mmol) of cyclooxalate dimer B1 was placed in a dry polymerization flask and placed in an oil bath at 180 °C under a nitrogen atmosphere. 2.70 mg (0.01 mmol) of octadecyl alcohol and 1.60 mg (0.05 mmol) of tetrabutyl titanate catalyst were added, and the reaction was carried out at 180 °C for 2 h. After the reaction was completed, the obtained pulverized / crushed polymerization product was extracted with dichloromethane and then vacuum dried to remove the solvent, finally yielding 5.66 g of product C1 (yield 97.6%). The intrinsic viscosity of the product was tested to be 1.22 dL / g.

[0063] Example 5

[0064] 5.80 g (50.0 mmol) of cyclooxalate monomer A1 was placed in a dry polymerization flask and placed in an oil bath at 160 °C under a nitrogen atmosphere. After the monomer melted, 0.190 g (2.5 mmol) of 1,2-propanediol and 9.45 mg (0.05 mmol) of stannous chloride catalyst were added. The reaction was carried out at 160 °C for 1 h. After the reaction was completed, the obtained pulverized / crushed polymerization product was extracted with dichloromethane and then vacuum dried to remove the solvent, finally yielding 5.67 g of product C1 (yield 97.8%). The intrinsic viscosity of the product was tested to be 1.22 dL / g. The DSC test results are shown in the attached figure. Figure 3 , 4 .

[0065] Example 6

[0066] 0.116 g (1.0 mmol) of cyclooxalate monomer A1 was placed in a dry polymerization flask. 10 mL of γ-valerol solution was added under a nitrogen atmosphere to prepare a 0.50 mol / L solution. After the monomer dissolved, 3.04 mg (0.04 mmol) of 1,3-propanediol and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at 160 °C for 0.5 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.490 g of product C1 (yield 84.5%). The intrinsic viscosity of the product was tested to be 0.76 dL / g.

[0067] Example 7

[0068] 0.58 g (5.0 mmol) of cyclooxalate monomer A1 was placed in a dry polymerization flask. 5 mL of toluene solution was added under a nitrogen atmosphere to prepare a 1.0 mol / L solution. After the monomer dissolved, 1.00 mg (0.005 mmol) of octadecylamine and 13.00 mg (0.05 mmol) of diphenyl phosphate catalyst were added. The reaction was carried out at 80 °C for 8 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.452 g of product C1 (yield 77.9%). The intrinsic viscosity of the product was tested to be 0.71 dL / g.

[0069] Example 8

[0070] 1.16 g (10.0 mmol) of cyclooxalate monomer A1 was placed in a dry polymerization flask. 5 mL of tetrahydrofuran solution was added under a nitrogen atmosphere to prepare a 2.0 mol / L solution. After the monomer dissolved, 2.00 mg (0.002 mmol) of 1,6-hexanediol and 16.0 mg (0.05 mmol) of dodecylbenzenesulfonic acid catalyst were added. The reaction was carried out at 50 °C for 12 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.759 g of product C1 (yield 65.4%). The intrinsic viscosity of the product was tested to be 0.65 dL / g.

[0071] Example 9

[0072] 1.74 g (15.0 mmol) of cyclooxalate monomer A1 was placed in a dry polymerization flask. 5 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 3.0 mol / L solution. After the monomer dissolved, 6.00 mg (0.075 mmol) of 1,3-propanediol and 9.00 mg (0.03 mmol) of tetraisopropyl titanate catalyst were added. The reaction was carried out at 50 °C for 16 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was vacuum dried to obtain 1.49 g of product C1 (yield 85.6%). The intrinsic viscosity of the product was tested to be 0.58 dL / g. The product is white in color, as seen in the attached digital photograph. Figure 6 .

[0073] Example 10

[0074] 6.40 g (50.0 mmol) of cyclooxalate monomer A2 was placed in a dry polymerization flask and placed in an oil bath at 60 °C under a nitrogen atmosphere. After the monomer melted, 1.00 mg (0.000025 mmol) of stannous octoate catalyst was added, and the reaction was carried out at 60 °C for 48 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane, followed by precipitation with a large amount of methanol. The resulting polyoxalate was then vacuum dried to obtain 6.29 g of product C2 (yield 98.3%). The intrinsic viscosity of the product was tested to be 1.10 dL / g. The MALDI-TOF MS spectrum is shown in the attached image. Figure 10 .

[0075] Example 11

[0076] 6.40 g (50.0 mmol) of cyclooxalate monomer A2 was placed in a dry polymerization flask and placed in an oil bath at 150 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.025 mmol) of benzyl alcohol and 18 mg (0.0005 mmol) of basic bismuth salicylate catalyst were added. The reaction was carried out at 150 °C for 5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.26 g of product C2 (yield 97.8%). The intrinsic viscosity of the product was tested to be 2.86 dL / g.

[0077] Example 12

[0078] 6.40 g (50.0 mmol) of cyclooxalate monomer A2 was placed in a dry polymerization flask and placed in an oil bath at 200 °C under a nitrogen atmosphere. After the monomer melted, 3.10 mg (0.05 mmol) of ethylene glycol and 17.1 mg (0.025 mmol) of stannous stearate catalyst were added. The reaction was carried out at 200 °C for 0.5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.27 g of product C2 (yield 98.0%). The intrinsic viscosity of the product was tested to be 1.12 dL / g. The 1H NMR spectrum of the product is shown in the appendix. Figure 7 .

[0079] Example 13

[0080] 6.40 g (25.0 mmol) of cyclooxalate dimer B2 was placed in a dry polymerization flask and placed in an oil bath at 180 °C under a nitrogen atmosphere. 2.70 mg (0.01 mmol) of octadecyl alcohol and 16 mg (0.05 mmol) of tetrabutyl titanate catalyst were added, and the reaction was carried out at 180 °C for 2 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.23 g of product C2 (yield 97.3%). The intrinsic viscosity of the product was tested to be 1.15 dL / g.

[0081] Example 14

[0082] 0.640 g (5.00 mmol) of cyclooxalate monomer A2 was placed in a dry polymerization flask. 5 mL of toluene solution was added under a nitrogen atmosphere to prepare a 1.0 mol / L solution. After the monomer dissolved, 0.52 mg (0.005 mmol) of neopentyl glycol and 13.0 mg (0.05 mmol) of diphenyl phosphate catalyst were added. The reaction was carried out at 80 °C for 8 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.489 g of product C2 (yield 76.4%). The intrinsic viscosity of this product was tested to be 0.68 dL / g. The DSC results are shown in the attached figure. Figure 8 , 9 .

[0083] Example 15

[0084] 1.28 g (10.0 mmol) of cyclooxalate monomer A2 was placed in a dry polymerization flask. 5 mL of tetrahydrofuran solution was added under a nitrogen atmosphere to prepare a 2.0 mol / L solution. After the monomer dissolved, 2.00 mg (0.002 mmol) of 1,6-hexanediol and 16.0 mg (0.05 mmol) of dodecylbenzenesulfonic acid catalyst were added. The reaction was carried out at 40 °C for 12 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.867 g of product C2 (yield 67.7%). The intrinsic viscosity of the product was tested to be 0.63 dL / g. The product is white in color, as seen in the attached digital photograph. Figure 11 .

[0085] Example 16

[0086] 1.74 g (15.0 mmol) of cyclooxalate monomer A2 was placed in a dry polymerization flask. 5 mL of dimethyl sulfoxide solution was added under a nitrogen atmosphere to prepare a 3.0 mol / L solution. After the monomer dissolved, 6.00 mg (0.075 mmol) of 1,3-propanediol and 9.00 mg (0.03 mmol) of tetraisopropyl titanate catalyst were added. The reaction was carried out at 50 °C for 16 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 1.47 g of product C2 (yield 84.5%). The intrinsic viscosity of this product was tested to be 0.54 dL / g. The MALDI-TOF MS spectrum is shown in the attached image. Figure 15 .

[0087] Example 17

[0088] 6.50 g (50.0 mmol) of cyclooxalate monomer A3 was placed in a dry polymerization flask and placed in an oil bath at 200 °C under a nitrogen atmosphere. After the monomer melted, 1.00 mg (0.000025 mmol) of stannous octoate catalyst was added, and the reaction was carried out at 200 °C for 1.5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.38 g of product C3 (yield 98.2%). The intrinsic viscosity of the product was tested to be 3.12 dL / g. The 1H NMR spectrum of the product is shown in the appendix. Figure 12 .

[0089] Example 18

[0090] 6.50 g (50.0 mmol) of cyclooxalate monomer A3 was placed in a dry polymerization flask and placed in an oil bath at 210 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.025 mmol) of benzyl alcohol and 18.0 mg (0.0005 mmol) of basic bismuth salicylate catalyst were added. The reaction was carried out at 210 °C for 0.5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.36 g of product C3 (yield 97.8%). The intrinsic viscosity of the product was tested to be 1.02 dL / g.

[0091] Example 19

[0092] 6.50 g (50.0 mmol) of cyclooxalate monomer A3 was placed in a dry polymerization flask and placed in an oil bath at 220 °C under a nitrogen atmosphere. After the monomer melted, 3.10 mg (0.05 mmol) of ethylene glycol and 9.00 mg (0.025 mmol) of stannous benzoate catalyst were added. The reaction was carried out at 220 °C for 0.8 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.40 g of product C3 (yield 98.5%). The intrinsic viscosity of the product was tested to be 1.12 dL / g. The DSC test results are shown in the attached figure. Figure 13 , 14 .

[0093] Example 20

[0094] 6.50 g (50.0 mmol) of cyclooxalate monomer A3 was placed in a dry polymerization flask and placed in an oil bath at 200 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.01 mmol) of octadecyl alcohol and 0.160 g (0.5 mmol) of tetrabutyl titanate catalyst were added. The reaction was carried out at 200 °C for 2 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.31 g of product C3 (yield 97.1%). The intrinsic viscosity of the product was tested to be 1.09 dL / g.

[0095] Example 21

[0096] 6.50 g (50.0 mmol) of cyclooxalate monomer A3 was placed in a dry polymerization flask and placed in an oil bath at 210 °C under a nitrogen atmosphere. After the monomer melted, 0.90 mg (0.01 mmol) of 1,4-butanediol and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at 210 °C for 1 h. After the reaction was completed, a large amount of methanol was used for precipitation. The resulting polyoxalate was then vacuum dried to obtain 6.36 g of product C3 (yield 97.8%). The intrinsic viscosity of the product was tested to be 1.10 dL / g.

[0097] Example 22

[0098] 0.650 g (5.00 mmol) of cyclooxalate monomer A3 was placed in a dry polymerization flask. 10.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 0.5 mol / L solution. After the monomer dissolved, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at room temperature for 24 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.564 g of product C3 (yield 86.8%). The intrinsic viscosity of the product was tested to be 0.73 dL / g.

[0099] Example 23

[0100] 0.650 g (5.00 mmol) of cyclooxalate monomer A3 was placed in a dry polymerization flask. 5.0 mL of toluene solution was added under a nitrogen atmosphere to prepare a 1.0 mol / L solution. After the monomer dissolved, 0.930 mg (0.005 mmol) of lauryl alcohol and 13.0 mg (0.05 mmol) of diphenyl phosphate catalyst were added. The reaction was carried out at 100 °C for 8 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.512 g of product C3 (yield 78.8%). The intrinsic viscosity of the product was tested to be 0.63 dL / g.

[0101] Example 24

[0102] 1.30 g (10.0 mmol) of cyclooxalate monomer A3 was placed in a dry polymerization flask. 5.0 mL of tetrahydrofuran solution was added under a nitrogen atmosphere to prepare a 2.0 mol / L solution. After the monomer dissolved, 2.00 mg (0.002 mmol) of 1,6-hexanediol and 16.0 mg (0.05 mmol) of dodecylbenzenesulfonic acid catalyst were added. The reaction was carried out at 50 °C for 12 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.902 g of product C3 (yield 69.4%). The intrinsic viscosity of the product was tested to be 0.68 dL / g.

[0103] Example 25

[0104] 1.95 g (10.0 mmol) of cyclooxalate dimer B3 was placed in a dry polymerization flask. 5 mL of γ-valerol solution was added under a nitrogen atmosphere to prepare a 3.0 mol / L solution. 38.0 mg (0.50 mmol) of 1,3-propanediol and 60.0 mg (0.2 mmol) of tetraisopropyl titanate catalyst were added. The reaction was carried out at 200 °C for 0.1 h. After the reaction was completed, the reaction solution was added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 1.02 g of product C3 (yield 52.3%). The intrinsic viscosity of the product was tested to be 0.51 dL / g.

[0105] Example 26

[0106] 7.90 g (50 mmol) of cyclooxalate monomer A4 was placed in a dry polymerization flask and placed in an oil bath at 210 °C under a nitrogen atmosphere. After the monomer melted, 1.00 mg (0.000025 mmol) of stannous octoate catalyst was added, and the reaction was carried out at 210 °C for 2 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.77 g of product C4 (yield 98.4%). The intrinsic viscosity of the product was tested to be 1.02 dL / g.

[0107] Example 27

[0108] 7.90 g (50 mmol) of cyclooxalate monomer A4 was placed in a dry polymerization flask and placed in an oil bath at 220 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.025 mmol) of benzyl alcohol and 18.0 mg (0.0005 mmol) of basic bismuth salicylate catalyst were added. The reaction was carried out at 220 °C for 0.2 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.73 g of product C4 (yield 97.8%). The intrinsic viscosity of the product was tested to be 1.12 dL / g.

[0109] Example 28

[0110] 7.90 g (50 mmol) of cyclooxalate monomer A4 was placed in a dry polymerization flask and placed in a salt bath at 230 °C under a nitrogen atmosphere. After the monomer melted, 3.10 mg (0.05 mmol) of ethylene glycol and 9.00 mg (0.025 mmol) of stannous benzoate catalyst were added. The reaction was carried out at 230 °C for 1 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.74 g of product C4 (yield 98.0%). The intrinsic viscosity of the product was tested to be 3.30 dL / g.

[0111] Example 29

[0112] 7.90 g (50 mmol) of cyclooxalate monomer A4 was placed in a dry polymerization flask and placed in a salt bath at 240 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.01 mmol) of octadecyl alcohol and 16.0 mg (0.05 mmol) of tetrabutyl titanate catalyst were added. The reaction was carried out at 240 °C for 0.5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.66 g of product C4 (yield 97.0%). The intrinsic viscosity of the product was tested to be 1.09 dL / g.

[0113] Example 30

[0114] 7.90 g (50 mmol) of cyclooxalate monomer A4 was placed in a dry polymerization flask and placed in an oil bath at 210 °C under a nitrogen atmosphere. After the monomer melted, 1.18 mg (0.01 mmol) of ethyl lactate and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at 210 °C for 3 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.73 g of product C4 (yield 97.8%). The intrinsic viscosity of the product was tested to be 1.10 dL / g.

[0115] Example 31

[0116] 0.790 g (5.00 mmol) of cyclooxalate monomer A4 was placed in a dry polymerization flask. 10.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 0.5 mol / L solution. After the monomer dissolved, 2.70 mg (0.01 mmol) of octadecylamine and 0.08 mg (0.0005 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at room temperature for 24 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.630 g of product C4 (yield 79.7%). The intrinsic viscosity of the product was tested to be 0.68 dL / g.

[0117] Example 32

[0118] 0.790 g (5.00 mmol) of cyclooxalate monomer A4 was placed in a dry polymerization flask. 5.0 mL of toluene solution was added under a nitrogen atmosphere to prepare a 1.0 mol / L solution. After the monomer dissolved, 1.00 mg (0.005 mmol) of octadecylamine and 13.0 mg (0.05 mmol) of diphenyl phosphate catalyst were added. The reaction was carried out at 100 °C for 8 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.650 g of product C4 (yield 82.3%). The intrinsic viscosity of the product was tested to be 0.74 dL / g.

[0119] Example 33

[0120] 1.58 g (10.0 mmol) of cyclooxalate monomer A4 was placed in a dry polymerization flask. 5.0 mL of tetrahydrofuran solution was added under a nitrogen atmosphere to prepare a 2.0 mol / L solution. After the monomer dissolved, 2.00 mg (0.002 mmol) of 1,6-hexanediol and 16.0 mg (0.05 mmol) of dodecylbenzenesulfonic acid catalyst were added. The reaction was carried out at 50 °C for 12 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 1.03 g of product C4 (yield 65.2%). The intrinsic viscosity of the product was tested to be 0.62 dL / g.

[0121] Example 34

[0122] 2.37 g (7.5 mmol) of cyclooxalate dimer B4 was placed in a dry polymerization flask. 5.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 3.0 mol / L solution. After the dimer dissolved, 6.00 mg (0.075 mmol) of 1,3-propanediol and 9.00 mg (0.03 mmol) of tetraisopropyl titanate catalyst were added. The reaction was carried out at 50 °C for 16 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 2.00 g of product C4 (yield 84.4%). The intrinsic viscosity of the product was tested to be 0.53 dL / g.

[0123] Example 35

[0124] 7.20 g (50.0 mmol) of cyclooxalate monomer A5 was placed in a dry polymerization flask and placed in an oil bath at 190 °C under a nitrogen atmosphere. After the monomer melted, 1.00 mg (0.000025 mmol) of stannous octoate catalyst was added, and the reaction was carried out at 190 °C for 2 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.06 g of product C5 (yield 98.1%). The intrinsic viscosity of the product was tested to be 3.45 dL / g.

[0125] Example 36

[0126] 7.20 g (50.0 mmol) of cyclooxalate monomer A5 was placed in a dry polymerization flask and placed in an oil bath at 150 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.025 mmol) of benzyl alcohol and 0.254 mg (0.0005 mmol) of bismuth stearate catalyst were added. The reaction was carried out at 150 °C for 6 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.04 g of product C5 (yield 97.8%). The intrinsic viscosity of the product was tested to be 1.12 dL / g.

[0127] Example 37

[0128] 7.20 g (50.0 mmol) of cyclooxalate monomer A5 was placed in a dry polymerization flask and placed in an oil bath at 170 °C under a nitrogen atmosphere. After the monomer melted, 3.10 mg (0.05 mmol) of ethylene glycol and 9.00 mg (0.025 mmol) of stannous benzoate catalyst were added. The reaction was carried out at 170 °C for 5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.07 g of product C5 (yield 98.2%). The intrinsic viscosity of the product was tested to be 1.08 dL / g.

[0129] Example 38

[0130] 7.20 g (50.0 mmol) of cyclooxalate monomer A5 was placed in a dry polymerization flask and placed in an oil bath at 200 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.01 mmol) of octadecyl alcohol and 16.0 mg (0.05 mmol) of tetrabutyl titanate catalyst were added. The reaction was carried out at 200 °C for 0.5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.00 g of product C5 (yield 97.2%). The intrinsic viscosity of the product was tested to be 0.99 dL / g.

[0131] Example 39

[0132] 7.20 g (50.0 mmol) of cyclooxalate monomer A5 was placed in a dry polymerization flask and placed in an oil bath at 180 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at 180 °C for 3 h. After the reaction was completed, a large amount of methanol was used for precipitation. The resulting polyoxalate was then vacuum dried to obtain 7.02 g of product C5 (yield 97.5%). The intrinsic viscosity of the product was tested to be 1.00 dL / g.

[0133] Example 40

[0134] 0.720 g (5.00 mmol) of cyclooxalate monomer A5 was placed in a dry polymerization flask. 10.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 0.5 mol / L solution. After the monomer dissolved, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at room temperature for 48 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.649 g of product C5 (yield 90.1%). The intrinsic viscosity of the product was tested to be 0.77 dL / g.

[0135] Example 41

[0136] 0.720 g (5.00 mmol) of cyclooxalate monomer A5 was placed in a dry polymerization flask. Under a nitrogen atmosphere, 5.0 mL of dimethyl sulfoxide solution was added to prepare a 1.0 mol / L solution. After the monomer dissolved, 1.00 mg (0.005 mmol) of octadecylamine and 13.0 mg (0.05 mmol) of diphenyl phosphate catalyst were added. The reaction was carried out at 80 °C for 12 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.615 g of product C5 (yield 85.4%). The intrinsic viscosity of this product was tested to be 0.73 dL / g.

[0137] Example 42

[0138] 1.44 g (10.0 mmol) of cyclooxalate monomer A5 was placed in a dry polymerization flask. 5.0 mL of tetrahydrofuran solution was added under a nitrogen atmosphere to prepare a 2.0 mol / L solution. After the monomer dissolved, 0.232 mg (0.002 mmol) of 1,6-hexanediamine and 16.0 mg (0.05 mmol) of dodecylbenzenesulfonic acid catalyst were added. The reaction was carried out at 50 °C for 24 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 1.27 g of product C5 (yield 88.2%). The intrinsic viscosity of the product was tested to be 0.68 dL / g.

[0139] Example 43

[0140] 2.16 g (7.5 mmol) of cyclooxalate dimer B5 was placed in a dry polymerization flask. 5.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 3.0 mol / L solution. After the dimer dissolved, 6.00 mg (0.075 mmol) of 1,3-propanediol and 9.00 mg (0.03 mmol) of tetraisopropyl titanate catalyst were added. The reaction was carried out at 50 °C for 16 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 1.97 g of product C5 (yield 91.2%). The intrinsic viscosity of the product was tested to be 0.56 dL / g.

[0141] Example 44

[0142] 8.00 g (50.0 mmol) of cyclooxalate monomer A6 was placed in a dry polymerization flask and placed in an oil bath at 140 °C under a nitrogen atmosphere. After the monomer melted, 1.00 mg (0.000025 mmol) of stannous octoate catalyst was added, and the reaction was carried out at 140 °C for 48 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.88 g of product C6 (yield 98.5%). The intrinsic viscosity of the product was tested to be 1.10 dL / g.

[0143] Example 45

[0144] 8.00 g (50.0 mmol) of cyclooxalate monomer A6 was placed in a dry polymerization flask and placed in an oil bath at 150 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.025 mmol) of benzyl alcohol and 2.22 mg (0.0005 mmol) of triphenylbismuth catalyst were added. The reaction was carried out at 150 °C for 6 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.82 g of product C6 (yield 97.8%). The intrinsic viscosity of the product was tested to be 2.98 dL / g.

[0145] Example 46

[0146] 8.00 g (50.0 mmol) of cyclooxalate monomer A6 was placed in a dry polymerization flask and placed in an oil bath at 170 °C under a nitrogen atmosphere. After the monomer melted, 3.10 mg (0.05 mmol) of ethylene glycol and 9.00 mg (0.025 mmol) of stannous benzoate catalyst were added. The reaction was carried out at 170 °C for 5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.84 g of product C6 (yield 98.0%). The intrinsic viscosity of the product was tested to be 1.08 dL / g.

[0147] Example 47

[0148] 8.00 g (50.0 mmol) of cyclooxalate monomer A6 was placed in a dry polymerization flask and placed in an oil bath at 180 °C under a nitrogen atmosphere. After the monomer melted, 0.610 mg (0.01 mmol) of ethanolamine and 16.0 mg (0.05 mmol) of tetrabutyl titanate catalyst were added. The reaction was carried out at 180 °C for 4 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.81 g of product C6 (yield 97.6%). The intrinsic viscosity of the product was tested to be 1.15 dL / g.

[0149] Example 48

[0150] 8.00 g (50.0 mmol) of cyclooxalate monomer A6 was placed in a dry polymerization flask and placed in an oil bath at 200 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at 200 °C for 2 h. After the reaction was completed, a large amount of methanol was used for precipitation. The polyoxalate was then vacuum dried to obtain 7.79 g of product C6 (yield 97.4%). The intrinsic viscosity of the product was tested to be 1.00 dL / g.

[0151] Example 49

[0152] 0.80 g (5.00 mmol) of cyclooxalate monomer A6 was placed in a dry polymerization flask. 10.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 0.5 mol / L solution. After the monomer dissolved, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at room temperature for 36 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.718 g of product C6 (yield 89.8%). The intrinsic viscosity of the product was tested to be 0.79 dL / g.

[0153] Example 50

[0154] 0.80 g (5.00 mmol) of cyclooxalate monomer A6 was placed in a dry polymerization flask. 5.0 mL of toluene solution was added under a nitrogen atmosphere to prepare a 1 mol / L solution. After the monomer dissolved, 0.10 mg (0.0005 mmol) of octadecylamine and 13.0 mg (0.05 mmol) of diphenyl phosphate catalyst were added. The reaction was carried out at 80 °C for 48 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.730 g of product C6 (yield 91.3%). The intrinsic viscosity of the product was tested to be 0.77 dL / g.

[0155] Example 51

[0156] 1.60 g (10.0 mmol) of cyclooxalate monomer A6 was placed in a dry polymerization flask. 5.0 mL of tetrahydrofuran solution was added under a nitrogen atmosphere to prepare a 2.0 mol / L solution. After the monomer dissolved, 2.00 mg (0.002 mmol) of 1,6-hexanediol and 16.0 mg (0.05 mmol) of dodecylbenzenesulfonic acid catalyst were added. The reaction was carried out at 40 °C for 24 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 1.23 g of product C6 (yield 76.9%). The intrinsic viscosity of the product was tested to be 0.69 dL / g.

[0157] Example 52

[0158] 2.40 g (12.5 mmol) of cyclooxalate dimer B6 was placed in a dry polymerization flask. 5.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 3.0 mol / L solution. 6.00 mg (0.075 mmol) of 1,3-propanediol and 9.00 mg (0.03 mmol) of tetraisopropyl titanate catalyst were added. The reaction was carried out at 50 °C for 16 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 2.03 g of product C6 (yield 84.6%). The intrinsic viscosity of the product was tested to be 0.55 dL / g.

[0159] Example 53

[0160] 8.60 g (50.0 mmol) of cyclooxalate monomer A7 was placed in a dry polymerization flask and placed in an oil bath at 140 °C under a nitrogen atmosphere. After the monomer melted, 1.00 mg (0.000025 mmol) of stannous octoate catalyst was added, and the reaction was carried out at 140 °C for 7 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 8.45 g of product C7 (yield 98.3%). The intrinsic viscosity of the product was tested to be 1.10 dL / g.

[0161] Example 54

[0162] 8.60 g (50.0 mmol) of cyclooxalate monomer A7 was placed in a dry polymerization flask and placed in an oil bath at 150 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.025 mmol) of benzyl alcohol and 18.0 mg (0.0005 mmol) of basic bismuth salicylate catalyst were added. The reaction was carried out at 150 °C for 6 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 8.41 g of product C7 (yield 97.8%). The intrinsic viscosity of the product was tested to be 1.13 dL / g.

[0163] Example 55

[0164] 8.60 g (50.0 mmol) of cyclooxalate monomer A7 was placed in a dry polymerization flask and placed in an oil bath at 170 °C under a nitrogen atmosphere. After the monomer melted, 3.10 mg (0.05 mmol) of ethylene glycol and 9.00 mg (0.025 mmol) of stannous benzoate catalyst were added. The reaction was carried out at 170 °C for 5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 8.43 g of product C7 (yield 98.0%). The intrinsic viscosity of the product was tested to be 1.08 dL / g.

[0165] Example 56

[0166] 8.60 g (50.0 mmol) of cyclooxalate monomer A7 was placed in a dry polymerization flask and placed in an oil bath at 180 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.01 mmol) of octadecyl alcohol and 16.0 mg (0.05 mmol) of tetrabutyl titanate catalyst were added. The reaction was carried out at 180 °C for 4 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 8.40 g of product C7 (yield 97.7%). The intrinsic viscosity of the product was tested to be 3.09 dL / g.

[0167] Example 57

[0168] 8.60 g (50.0 mmol) of cyclooxalate monomer A7 was placed in a dry polymerization flask and placed in an oil bath at 200 °C under a nitrogen atmosphere. After the monomer melted, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at 200 °C for 2 h. After the reaction was completed, a large amount of methanol was used for precipitation. The polyoxalate was then vacuum dried to obtain 8.38 g of product C7 (yield 97.4%). The intrinsic viscosity of the product was tested to be 1.01 dL / g.

[0169] Example 58

[0170] 0.860 g (5.00 mmol) of cyclooxalate monomer A7 was placed in a dry polymerization flask. 10.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 0.5 mol / L solution. After the monomer dissolved, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at room temperature for 48 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.738 g of product C7 (yield 85.8%). The intrinsic viscosity of the product was tested to be 0.98 dL / g.

[0171] Example 59

[0172] 0.860 g (5.00 mmol) of cyclooxalate monomer A7 was placed in a dry polymerization flask. 5.0 mL of toluene solution was added under a nitrogen atmosphere to prepare a 1.0 mol / L solution. After the monomer dissolved, 1.00 mg (0.005 mmol) of octadecylamine and 13.0 mg (0.05 mmol) of diphenyl phosphate catalyst were added. The reaction was carried out at 80 °C for 12 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.800 g of product C7 (yield 93.0%). The intrinsic viscosity of the product was tested to be 1.04 dL / g.

[0173] Example 60

[0174] 1.72 g (10.0 mmol) of cyclooxalate monomer A7 was placed in a dry polymerization flask. 5.0 mL of tetrahydrofuran solution was added under a nitrogen atmosphere to prepare a 2.0 mol / L solution. After the monomer dissolved, 2.00 mg (0.002 mmol) of 1,6-hexanediol and 16.0 mg (0.05 mmol) of dodecylbenzenesulfonic acid catalyst were added. The reaction was carried out at 40 °C for 36 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 1.37 g of product C7 (yield 79.7%). The intrinsic viscosity of the product was tested to be 0.87 dL / g.

[0175] Example 61

[0176] 2.58 g (10.0 mmol) of cyclooxalate dimer B7 was placed in a dry polymerization flask. 5.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 3.0 mol / L solution. After the monomer dissolved, 6.00 mg (0.075 mmol) of 1,3-propanediol and 9.00 mg (0.03 mmol) of tetraisopropyl titanate catalyst were added. The reaction was carried out at 50 °C for 16 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 2.15 g of product C7 (yield 83.3%). The intrinsic viscosity of the product was tested to be 0.55 dL / g.

[0177] Example 62

[0178] 2.90 g (25.0 mmol) of cyclooxalate monomer A1, 3.20 g (25.0 mmol) of cyclooxalate monomer A2, and 3.20 g (25.0 mmol) of cyclooxalate monomer A2 were placed in a dry polymerization flask and placed in an oil bath at 140 °C under a nitrogen atmosphere. After the monomers melted, 1.00 mg (0.000025 mmol) of stannous octoate catalyst was added, and the reaction was carried out at 140 °C for 7 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 5.75 g of copolymer product containing both C1 and C2 structures in the molecular chain (yield 94.3%). The intrinsic viscosity of the product was tested to be 1.14 dL / g.

[0179] Example 63

[0180] 3.25 g (25.0 mmol) of cyclooxalate monomer A3 and 3.95 g (25.0 mmol) of cyclooxalate A4 were placed in a dry polymerization flask and placed in an oil bath at 150 °C under a nitrogen atmosphere. After the monomers melted, 2.70 mg (0.025 mmol) of benzyl alcohol and 18.0 mg (0.0005 mmol) of basic bismuth salicylate catalyst were added. The reaction was carried out at 150 °C for 6 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.85 g of copolymer product containing both C3 and C4 structures in the molecular chain (yield 95.1%). The intrinsic viscosity of the product was tested to be 1.09 dL / g.

[0181] Example 64

[0182] 2.88 g (20.0 mmol) of cyclooxalate monomer A5 and 4.80 g (30.0 mmol) of cyclooxalate monomer A6 were placed in a dry polymerization flask and placed in an oil bath at 170 °C under a nitrogen atmosphere. After the monomers melted, 3.10 mg (0.05 mmol) of ethylene glycol and 9.00 mg (0.025 mmol) of stannous benzoate catalyst were added. The reaction was carried out at 170 °C for 5 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.43 g of copolymer product containing both C5 and C6 structures in the molecular chain (yield 96.7%). The intrinsic viscosity of the product was tested to be 2.96 dL / g.

[0183] Example 65

[0184] 4.32 g (30.0 mmol) of cyclooxalate monomer A5 and 3.44 g (20.0 mmol) of cyclooxalate monomer A7 were placed in a dry polymerization flask and placed in an oil bath at 180 °C under a nitrogen atmosphere. After the monomers melted, 2.70 mg (0.01 mmol) of octadecyl alcohol and 16.0 mg (0.05 mmol) of tetrabutyl titanate catalyst were added. The reaction was carried out at 180 °C for 4 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 7.31 g of copolymer product containing both C5 and C7 structures in the molecular chain (yield 94.2%). The intrinsic viscosity of the product was tested to be 1.17 dL / g.

[0185] Example 66

[0186] 4.64 g (40.0 mmol) of cyclooxalate monomer A1 and 1.58 g (10.0 mmol) of cyclooxalate monomer A4 were placed in a dry polymerization flask and placed in an oil bath at 200 °C under a nitrogen atmosphere. After the monomers melted, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at 200 °C for 2 h. After the reaction was completed, a large amount of methanol was used for precipitation. The resulting polyoxalate was then vacuum dried to obtain 6.05 g of copolymer containing both C1 and C4 structures in the molecular chain (yield 97.3%). The intrinsic viscosity of the product was tested to be 1.28 dL / g.

[0187] Example 67

[0188] 0.320 g (2.50 mmol) of cyclooxalate monomer A2 and 0.43 g (2.50 mmol) of cyclooxalate monomer A7 were placed in a dry polymerization flask. 10.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 0.5 mol / L solution. After the monomers dissolved, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at room temperature for 24 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.586 g of copolymer product containing both C2 and C7 structures in the molecular chain (yield 78.1%). The intrinsic viscosity of the product was tested to be 0.82 dL / g.

[0189] Example 68

[0190] 0.232 g (2.00 mmol) of cyclooxalate monomer A1 and 0.432 g (3.00 mmol) of cyclooxalate monomer A5 were placed in a dry polymerization flask. 5.0 mL of toluene solution was added under a nitrogen atmosphere to prepare a 1.0 mol / L solution. After the monomers dissolved, 1.00 mg (0.005 mmol) of octadecylamine and 13.0 mg (0.05 mmol) of diphenyl phosphate catalyst were added. The reaction was carried out at 80 °C for 12 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 0.552 g of copolymer product containing both C1 and C5 structures in the molecular chain (yield 83.1%). The intrinsic viscosity of the product was tested to be 0.79 dL / g.

[0191] Example 69

[0192] 0.650 g (50.0 mmol) of cyclooxalate monomer A3 and 0.720 g (50.0 mmol) of cyclooxalate monomer A5 were placed in a dry polymerization flask. 5.0 mL of tetrahydrofuran solution was added under a nitrogen atmosphere to prepare a 2.0 mol / L solution. After the monomers dissolved, 2.00 mg (0.002 mmol) of 1,6-hexanediol and 16.0 mg (0.05 mmol) of dodecylbenzenesulfonic acid catalyst were added. The reaction was carried out at 40 °C for 36 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 1.10 g of copolymer product containing both C3 and C5 structures in the molecular chain (yield 80.3%). The intrinsic viscosity of the product was tested to be 0.75 dL / g.

[0193] Example 70

[0194] 0.650 g (5.00 mmol) of cyclooxalate monomer A3 and 1.72 g (10.0 mmol) of cyclooxalate monomer A7 were placed in a dry polymerization flask. 5.0 mL of chloroform solution was added under a nitrogen atmosphere to prepare a 3.0 mol / L solution. After the monomers dissolved, 6.00 mg (0.075 mmol) of 1,3-propanediol and 9.00 mg (0.03 mmol) of tetraisopropyl titanate catalyst were added. The reaction was carried out at 50 °C for 16 h. After the reaction was completed, triethylamine was added to terminate the reaction. The reaction solution was then added to methanol solution for precipitation. Finally, the obtained polyoxalate was dried under vacuum to obtain 1.83 g of copolymer product containing both C3 and C7 structures in the molecular chain (yield 77.2%). The intrinsic viscosity of the product was tested to be 0.51 dL / g.

[0195] Example 71

[0196] 2.90 g (25.0 mmol) of cyclooxalate monomer A1 and 2.85 g (25.0 mmol) of ε-caprolactone were placed in a dry polymerization flask and placed in an oil bath at 140 °C under a nitrogen atmosphere. After the monomer melted, 1.00 mg (0.000025 mmol) of stannous octoate catalyst was added, and the reaction was carried out at 140 °C for 7 h. After the reaction was completed, the obtained polymer product was dissolved with dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 5.44 g of copolymer product containing both C1 and polycaprolactone segments in the molecular chain (yield 94.6%). The intrinsic viscosity of the product was tested to be 1.12 dL / g.

[0197] Example 72

[0198] 3.25 g (12.5 mmol) of cyclooxalate B3 and 3.95 g (25.0 mmol) of cyclooxalate A4 were placed in a dry polymerization flask and placed in an oil bath at 150 °C under a nitrogen atmosphere. 2.70 mg (0.025 mmol) of benzyl alcohol and 18.0 mg (0.0005 mmol) of basic bismuth salicylate catalyst were added, and the reaction was carried out at 150 °C for 6 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.76 g of copolymer product containing both C3 and C4 structures in the molecular chain (yield 93.9%). The intrinsic viscosity of the product was tested to be 1.02 dL / g.

[0199] Example 73

[0200] 2.88 g (20.0 mmol) of cyclooxalate monomer A5 and 4.32 g (30.0 mmol) of lactide monomer were placed in a dry polymerization flask and placed in an oil bath at 170 °C under a nitrogen atmosphere. After the monomers melted, 3.10 mg (0.05 mmol) of ethylene glycol and 9.00 mg (0.025 mmol) of stannous benzoate catalyst were added. The reaction was carried out at 170 °C for 3 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.94 g of copolymer product containing both C5 and polylactide segments in the molecular chain (yield 96.4%). The intrinsic viscosity of the product was tested to be 3.44 dL / g.

[0201] Example 74

[0202] 4.32 g (30.0 mmol) of cyclooxalate monomer A5 and 2.32 g (20.0 mmol) of glycolide monomer were placed in a dry polymerization flask and placed in an oil bath at 180 °C under a nitrogen atmosphere. After the monomers melted, 2.70 mg (0.01 mmol) of octadecyl alcohol and 16.0 mg (0.05 mmol) of tetrabutyl titanate catalyst were added. The reaction was carried out at 180 °C for 2 h. After the reaction was completed, the obtained polymer product was dissolved in dichloromethane and then precipitated with a large amount of methanol. Finally, the polyoxalate was vacuum dried to obtain 6.47 g of copolymer product containing both C5 and polyethylene glycolide segments in the molecular chain (yield 97.4%). The intrinsic viscosity of the product was tested to be 1.18 dL / g.

[0203] Example 75

[0204] 4.64 g (40.0 mmol) of cyclooxalate monomer A1 and 1.02 g (10.0 mmol) of cyclotrimethyl cyclocarbonate monomer were placed in a dry polymerization flask and placed in an oil bath at 200 °C under an argon atmosphere. After the monomers melted, 2.70 mg (0.01 mmol) of octadecylamine and 8.00 mg (0.05 mmol) of p-toluenesulfonic acid catalyst were added. The reaction was carried out at 200 °C for 1 h. After the reaction was completed, a large amount of methanol was used for precipitation. The polyoxalate obtained was then vacuum dried to obtain 5.38 g of copolymer product (yield 95.1%) containing both C1 and polycyclic trimethylene carbonate segments in the molecular chain. The intrinsic viscosity of the product was tested to be 1.08 dL / g.

Claims

1. A method for preparing polyoxalate by ring-opening polymerization of cyclooxalate monomers and their cyclic oligomers, characterized in that... This method involves bulk ring-opening polymerization of cyclic oxalate monomers and cyclic oxalate oligomers, or cyclic oxalate oligomers, or blends of cyclic oxalate monomers and cyclic oxalate oligomers with at least one of cyclic lactones, cyclic lactones, and cyclic carbonates, or blends of cyclic oxalate cyclic oligomers with at least one of cyclic lactones, cyclic lactones, and cyclic carbonates, under the action of a catalyst and an initiator, to obtain polyoxalates and copolymers of the following general structural formulas; alternatively, solution ring-opening polymerization can be performed to obtain polyoxalates and copolymers of the following general structural formulas: In the formula, R1 is any group, and the catalyst is any one of organobismuth catalyst or organotitanium catalyst; In the bulk ring-opening polymerization reaction, the molar ratio of the catalyst to the cyclic oxalate monomer and the cyclic oxalate oligomer, or the cyclic oxalate oligomer, is 1 / 20000 to 1 / 100; the molar ratio of the initiator to the cyclic oxalate monomer and the cyclic oxalate oligomer, or the cyclic oxalate oligomer, is 1 / 10000 to 1 / 20; the reaction temperature is 60 to 240 °C; and the reaction time is 0.1 to 48 hours. The cyclic oxalate monomer and cyclic oxalate oligomer, or the reaction solution prepared from the cyclic oxalate oligomer in the solution ring-opening polymerization reaction, have a concentration of 0.1~3 mol·L⁻¹. -1 The molar ratio of catalyst to cyclic oxalate monomer and cyclic oxalate oligomer, or cyclic oxalate oligomer, is 1 / 10000 to 1 / 50; the molar ratio of initiator to cyclic oxalate monomer and cyclic oxalate oligomer, or cyclic oxalate oligomer, is 1 / 10000 to 1 / 20; the reaction temperature is room temperature to 200 °C; and the reaction time is 0.1 to 48 hours. The structure of the cyclic oxalate monomer is as follows: A1 A2 A3 A4 A5 A6 or A7; The structure of the cyclic oxalate oligomer is as follows: B1 B2, B3 B4 B5 B6 or B7.

2. The method for preparing polyoxalate by ring-opening polymerization of cyclooxalate monomers and their cyclic oligomers according to claim 1, characterized in that... The solvent used to prepare the solution in the solution ring-opening polymerization reaction described in this method is any one of toluene, chloroform, tetrahydrofuran, dimethyl sulfoxide, or γ-valerolactone.

3. The method for preparing polyoxalate by ring-opening polymerization of cyclooxalate monomers and their cyclic oligomers according to claim 1, characterized in that... The cyclic oxalate monomers used in this method are monomers with 6-10 membered rings; the cyclic oxalate oligomers are cyclic dimers with 12-20 membered rings.

4. The method for preparing polyoxalate by ring-opening polymerization of cyclooxalate monomers and their cyclic oligomers according to any one of claims 1 to 3, characterized in that... The cyclic lactones, cyclic lactides, and cyclic carbonates mentioned in this method are lactide, glycolide, caprolactone, p-dioxanone, and cyclotrimethylene carbonate.

5. The method for preparing polyoxalate by ring-opening polymerization of cyclooxalate monomers and their cyclic oligomers according to any one of claims 1 to 3, characterized in that... The initiator described in this method is a trace amount of water and / or at least one of primary alcohol, secondary alcohol, primary amine and secondary amine contained in the cyclic oxalate monomer and its cyclic oligomer.

6. The method for preparing polyoxalate by ring-opening polymerization of cyclooxalate monomers and their cyclic oligomers according to claim 4, characterized in that... The initiator described in this method is a trace amount of water and / or at least one of primary alcohol, secondary alcohol, primary amine and secondary amine contained in the cyclic oxalate monomer and its cyclic oligomer.

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