A catalyst for catalyzing lactone homopolymerization and its use

Abstract

The application provides a catalyst for catalyzing lactone homopolymerization and application thereof, and has the following structure: (CH3)3N + (CH2) x COO － Wherein, x is an integer of 3-10. When the catalyst is used for catalyzing lactone homopolymerization, the reaction rate is fast, the monomer conversion rate is high, the obtained polymer is free of metal residues, the molecular weight is controllable and the molecular weight distribution is narrow.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polymer material preparation, and relates to a catalyst for catalyzing lactone homopolymerization, a method for preparing a cyclic lactone homopolymer and the obtained cyclic lactone homopolymer. BACKGROUND

[0002] Aliphatic polyesters have excellent biocompatibility and biodegradability, and are widely used in the fields of biological medicine and microelectronics. In recent ten years, aliphatic polyesters have become a hot research topic of synthetic biopolymers. Among various aliphatic polyesters, poly(trimethylene carbonate) (PTMC), polyglycolide (PGA), polylactide (PLA) and poly(p-dioxanone) (PPDO) homopolymers have become a class of promising biomedical materials (Biomater. Sci., 2017, 5(1), 9-21; J. Polym. Sci., Part A: Polym. Chem., 2005, 43, 2790-2799; Polym. Chem., 2021, 12, 1806-1815.).

[0003] Cyclic carbonate and lactone ring-opening polymerization is the main method for synthesizing aliphatic polyesters. Metal compounds are commonly used to catalyze lactone ring-opening polymerization in industry. Although metal catalysts have high activity in the ring-opening polymerization of cyclic esters, the metal impurities remaining in the polymer are difficult to remove and the cost is high, which seriously limits their application in the field of polyester preparation and in the fields of medicine and electronics. Organic catalysts have the advantages of environmental friendliness, low cost and no metal. Among them, bifunctional small organic molecule catalysts have the characteristics of simultaneously activating monomers and initiators. The ring-opening polymerization of cyclic lactones catalyzed by them has the characteristics of controllability, high efficiency and minimization of molecular transesterification, and the obtained polyesters have clear structure and narrow molecular weight distribution. So far, there are very few quaternary ammonium salt organic catalysts that can be used in this field. Only one document (ACS Sustainable Chem. Eng., 2019, 7, 8868-8875) reports that betaine is used as an organic catalyst for the ring-opening homopolymerization of trimethylene carbonate, and the activity for L-lactide homopolymerization is very low, and there is no report on effective catalysis of other monomers homopolymerization. In addition, a patent (CN 110396180 B) reports that betaine is used to catalyze the homopolymerization of pentanolactone or hexanolactone in the presence of an organic solvent.

[0004] Therefore, there is still a need for further research on catalysts for lactone homopolymerization by those skilled in the art to enhance the universality and catalytic activity of the catalysts for lactone homopolymerization. SUMMARY

[0005] The main purpose of the present application is to provide a catalyst for catalyzing lactone homopolymerization and its application, so as to overcome the defects of poor universality and low polymerization activity of the catalysts for lactone homopolymerization in the prior art.

[0006] To achieve the above object, the present application provides a catalyst for catalyzing lactone homopolymerization, which has the following structure:

[0007] (CH3)3N + (CH2) x COO － wherein x is an integer of 3-10.

[0008] In an embodiment of the catalyst for catalyzing lactone homopolymerization, x is 4, 7 or 10.

[0009] To achieve the above object, the present application further provides a method for preparing a cyclic lactone homopolymer, which uses a lactone as a monomer, uses (CH3)3N + (CH2) x COO － as a catalyst, and performs a bulk polymerization reaction in the presence of an initiator ROH to obtain a cyclic lactone homopolymer, and the reaction equation is as follows:

[0010]

[0011] wherein the lactone is trimethylene carbonate TMC, glycolide GA, lactide L-LA, or p-dioxanone PDO, x is an integer of 3-10, and R is a hydrocarbon group.

[0012] In an embodiment of the method for preparing a cyclic lactone homopolymer, x is 4 or 7 or 10.

[0013] In an embodiment of the method for preparing a cyclic lactone homopolymer, no solvent is added in the bulk polymerization reaction, and the reaction time is 9 minutes to 48 hours.

[0014] In an embodiment of the method for preparing a cyclic lactone homopolymer, the initiator is 3-phenylpropanol.

[0015] In an embodiment of the method for preparing a cyclic lactone homopolymer, the molar ratio of the initiator to the monomer is 1:15-50.

[0016] In an embodiment of the method for preparing a cyclic lactone homopolymer, the molar ratio of the catalyst to the monomer is 1:50-500.

[0017] In an embodiment of the method for preparing a cyclic lactone homopolymer, the temperature of the bulk polymerization reaction is 70-150°C.

[0018] To achieve the above object, the present application further provides a cyclic lactone homopolymer obtained by the above method.

[0019] The beneficial effects of this invention are:

[0020] The specific chain length of the catalyst of this invention helps to alleviate the ring strain of the transition state structure, stabilize the transition state, thereby reducing the activation energy barrier and improving catalytic activity.

[0021] The catalyst of this invention achieves the purpose of separately regulating the acidity of the trimethylamine quaternary ammonium salt cation and the basicity of the carboxylic acid anion by adjusting the chain length, thereby improving the catalytic activity of the catalyst through the regulation of acidity and basicity.

[0022] This invention utilizes a bifunctional long-chain trimethylamine carboxylate inner salt to catalyze the ring-opening polymerization of cyclic ester monomers to prepare aliphatic polyesters. The trimethylamine carboxylate inner salt catalyst exhibits good thermal stability, making it suitable for bulk polymerization systems requiring high reaction temperatures. It also demonstrates a fast reaction rate, high monomer conversion, and produces polymers free of metal residues, with controllable molecular weight and a narrow molecular weight distribution. Attached Figure Description

[0023] Figure 1 The product of Example 1 1 H NMR spectrum;

[0024] Figure 2 The product of Example 4 1 H NMR spectrum;

[0025] Figure 3 The product of Example 7 1 H NMR spectrum. Detailed Implementation

[0026] The technical solution of the present invention will be described in detail below. The following embodiments are implemented under the premise of the technical solution of the present invention and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following embodiments. Structures or experimental methods that do not specify specific conditions in the following embodiments are generally performed under conventional conditions.

[0027] This invention provides a catalyst for catalyzing the homopolymerization of lactones, the catalyst having the following structure:

[0028] (CH3)3N + (CH2) x COO － , where x is an integer between 3 and 10.

[0029] Specifically, the catalyst structure can be represented as follows:

[0030]

[0031] This invention utilizes the long-chain carboxylic acid trimethylamine inner salt [(CH3)3N(CH2)] xThe catalysts of the present application can successfully achieve ring-opening homopolymerization of cyclic carbonates and other lactones in the presence of initiators.

[0032] In detail, the present application obtains more accurate energy by density functional theory B3LYP calculation, molecular structure optimization under 6-31+G** basis set, and single-point energy calculation under larger basis set 6-311+G** considering weak interaction correction (D3-BJ) and solvation effect (IEFPCM). The theoretical calculation of the present application shows that the specific chain length of long-chain carboxylic acid trimethylamine inner salt is conducive to relieving the ring strain of the transition state structure of the reaction, stabilizing the transition state, thereby reducing the activation energy barrier and improving the catalytic activity. As shown in Table 1 below, the activation enthalpy of the rate-determining step of the long-chain carboxylic acid trimethylamine inner salt catalyzed trimethylene carbonate ring-opening polymerization (15.0-20.3 kcal / mol) is lower than that of the corresponding reaction catalyzed by betaine (25.3 kcal / mol). Therefore, the long-chain carboxylic acid trimethylamine inner salt may have higher catalytic activity than betaine. Further, based on the above theoretical calculation, the present application finds that when x = 4, 7, the activation enthalpy of the rate-determining step of the long-chain carboxylic acid trimethylamine inner salt catalyzed trimethylene carbonate ring-opening polymerization is lower, and therefore the corresponding catalyst has higher catalytic activity.

[0033] Table 1. Comparison of activation enthalpy of the rate-determining step of long-chain carboxylic acid trimethylamine inner salt catalyzed trimethylene carbonate ring-opening polymerization (the corresponding activation enthalpy of betaine catalyzed reaction is 25.3 kcal / mol)

[0034]

[0035] In addition, the catalytic activity of the catalyst for catalyzing lactone homopolymerization is largely regulated by the acidity and basicity of the catalyst. The present application can simultaneously regulate the acidity of the trimethylamine quaternary ammonium salt cation and the basicity of the carboxylate anion by a specific carbon chain length, because the quaternary ammonium salt cation is a strong electron-withdrawing group that will significantly affect the basicity of the carboxyl group to some extent. In the catalyst of the present application, the trimethylamine quaternary ammonium salt cation and the carboxylate anion are separated by 3-10 carbon atoms, which can well balance the acidity and basicity of the catalyst and reduce the interference between the trimethylamine quaternary ammonium salt cation and the carboxylate anion.

[0036] This theory can be confirmed by the fact that the pK a value (1.8) of betaine hydrochloride is significantly less than the pK a value (4.76) of acetic acid (Cf: Coronado et al. Angew. Chem. Int. Ed. 2004, 43, 6152-6156).

[0037] Further, the physicochemical properties of a compound are determined by its overall structure, and individual functional groups (or chain lengths) cannot be considered separately. The catalytic activity of the carboxylic acid trimethylamine inner salt of the present application is determined by its defined molecular structure, and a slight change in its structure can result in a significant change in its performance. The present application demonstrates through experimental data that the long-chain carboxylic acid trimethylamine inner salt proposed in the present application has higher catalytic activity than betaine in catalyzing TMC homopolymerization under the same conditions (see Example 1 and Comparative Example 1 below), and also has significantly higher catalytic activity than betaine in catalyzing L-LA polymerization (see Example 3 and Comparative Example 2 below).

[0038] In one embodiment, the present application is (CH3)3N + (CH2) x COO － In this case, x is 4 or 7, and the catalyst has higher catalytic activity.

[0039] The present application does not particularly limit the source of the above-mentioned catalyst, which is, for example, a commercially available product or is synthesized by the present application. The present application does not particularly limit the preparation method of the above-mentioned catalyst. In one embodiment, the catalyst of the present application is (CH3)3N + (CH2) x COO － It is synthesized by the following method:

[0040]

[0041] In a specific embodiment, the catalyst is prepared as follows:

[0042] Dissolve 3.12 g (15 mmol) of ethyl bromovalerate in 50 mL of ethanol under ice alcohol bath conditions, add to a sealed tube, then add 11 mL of a trimethylamine ethanol solution (mass fraction 30-35%), then heat to reflux at 87°C for 17 h, evaporate the volatile components. Dissolve the resulting sample in a small amount of deionized water, then slowly and uniformly add it to 75 mL of basic ion exchange resin, stand overnight, then rinse the product resin with deionized water until the product is completely washed out, concentrate, and vacuum dry to obtain a white solid C5 catalyst (x = 4). 1 H NMR (D2O) δ 1.55 (m, 2H), 1.72 (m, 2H), 2.18 (t, J = 7.3 Hz, 2H), 3.08 (s, 9H), 3.27 (m, 2H). 13 C NMR (D2O) δ 22.1, 22.5, 36.7, 52.8 [t, 1J(N,C) = 3.9 Hz], 66.3 [t, 1J(N,C) = 2.7 Hz], 182.4. [M+H] + : 160.1

[0043] Betaine: 1H NMR (D2O) δ 3.18 (s, 9H), 3.82 (s, 2H). 13 C NMR (D2O) δ 55.0, 68.0, 170.0.

[0044] Catalyst C8 (x = 7) MS [M+H] + : 202.2; and C11 (x = 10) [M+H] + : 244.2.

[0045] Therefore, the present application provides a metal-free, low-toxicity, monomer-universal and high-polymerization-activity small organic molecule catalyst for lactone homopolymerization.

[0046] In an embodiment, the present application further provides a method for preparing a cyclic lactone homopolymer, taking a lactone as a monomer, taking (CH3)3N + (CH2) x COO － as a catalyst, in the presence of an initiator ROH, performing bulk polymerization to obtain a cyclic lactone homopolymer, and the reaction equation is as follows:

[0047]

[0048] wherein the lactone is trimethylene carbonate TMC, glycolide GA, lactide L-LA, or p-dioxanone PDO, x is an integer of 3-10, and R is a hydrocarbon group.

[0049] Taking glycolide GA monomer as an example, the reaction equation for preparing a cyclic lactone homopolymer according to the present application is as follows:

[0050]

[0051] The catalyst of the present application can be applied to homopolymerization of various lactone monomers, and has the characteristic of good universality. In addition, the carboxylic acid trimethylamine inner salt catalyst of the present application has good thermal stability, can be used in a bulk polymerization system with high reaction temperature requirement, has a fast reaction rate, and the obtained polymer does not contain metal residues, has controllable molecular weight and narrow molecular weight distribution.

[0052] In an embodiment, the molar ratio of the catalyst carboxylic acid trimethylamine inner salt to the monomer is 1:50-500, and the molar ratio of the initiator to the monomer is 1:15-50. No solvent is added in the bulk polymerization reaction of the present application, which is conducive to increasing the reaction rate due to high monomer concentration, and the solvent-free reaction is also conducive to post-processing.

[0053] In an embodiment, the temperature of the bulk polymerization reaction of the present application is 70-150℃, and the reaction time is 9 minutes-48 hours.

[0054] The initiator of the present application is an alcohol, and its structural formula is ROH, wherein R is a hydrocarbon group, and in one embodiment, R can be an alkyl group, an alkenyl group or an aryl group, and in addition, R can have 1-10 carbon atoms. In another embodiment, the initiator of the present application is 3-phenylpropanol.

[0055] The catalyst of the present application is used for catalyzing the homopolymerization of cyclic ester, and due to the specific alkyl chain length and specific acid-base property, the ring tension of the transition state structure is released, the transition state is stabilized, and the polymerization activity is high.

[0056] The technical solutions of the present application will be further described in detail below through specific examples.

[0057] Example 1

[0058] Polytrimethylene carbonate (PTMC) is prepared by using trimethylammonium pentanoate inner salt (C5 catalyst, x is 4) as the catalyst under the condition that the molar ratio of monomer, catalyst and initiator is 500:1:10, and the preparation method comprises the following steps:

[0059] Under the protection of argon, TMC (1.6345 g, 16 mmol), trimethylammonium pentanoate inner salt (C5 catalyst, x is 4) (0.0051 g, 0.032 mmol) and initiator PPA (0.0441 g, 0.32 mmol) are added into a dry reaction tube. The reaction is stirred by a magnetic stirrer at 90°C for 15 min, and after the reaction is completed, a small amount of sample is taken from the reaction mixture, and the volatile matter is removed by vacuumization. The monomer conversion rate is measured by HNMR to be 90%. 1 The remaining reaction solution is rotary evaporated, the obtained crude product is dissolved in a minimum amount of dichloromethane, and a cold methanol solution is added, and the polymer is precipitated. The colorless viscous liquid PTMC is obtained by separation and purification, and the polymer has a molecular weight Mn of 4407 g / mol and a molecular weight distribution of 1.945. 1 The H NMR spectrum is as shown in Figure 1 , and the molecular weight Mn is 4407 g / mol and the molecular weight distribution is 1.945.

[0060] Example 2

[0061] The difference from Example 1 is that trimethylammonium octanoate inner salt (C8 catalyst, x is 7) is used as the catalyst, and the monomer conversion rate is 85%. The polymer has a molecular weight Mn of 3729 g / mol and a molecular weight distribution of 2.125.

[0062] Comparative Example 1

[0063] Under the same conditions of Example 1, betaine is used as the catalyst, the reaction is stirred by a magnetic stirrer at 90°C for 15 min, and the monomer conversion rate is 25%. Because the molecular weight of the polymer is low, the polymer is not precipitated. ​​

[0064] Example 3

[0065] Polylactide (PLLA) was prepared using trimethylammonium octanoate as a catalyst under conditions where the molar ratio of monomer, catalyst, and initiator was 50:1:1. The preparation method includes the following steps:

[0066] Under argon protection, L-LA (0.9224 g, 6.4 mmol), trimethylammonium octanoate inner salt (C8 catalyst) (0.0258 g, 0.128 mmol), and PPA (0.0174 g, 0.128 mmol) were added to a dry reaction tube. The reaction was magnetically stirred at 100 °C for 3 h. After the reaction, a small sample was taken from the mixture to remove volatiles under vacuum. 1 ¹H NMR showed a monomer conversion rate of 96%. The remaining reaction solution was rotary evaporated, and the crude product was dissolved in a minimal amount of dichloromethane. Upon addition of this to a cold methanol solution, polymer precipitated. Separation and purification yielded a white PLA powder. GPC analysis revealed the polymer's molecular weight (Mn) to be 4196 g / mol, and its molecular weight distribution was [not specified]. It is 1.14.

[0067] Comparative Example 2

[0068] Under the same conditions as in Example 3, L-LA polymerization was catalyzed using betaine and the reaction was carried out with magnetic stirring at 100°C for 3 hours, with a monomer conversion rate of 15%. Due to the low molecular weight of the polymer, no polymer precipitated.

[0069] Example 4

[0070] Polylactide (PLLA) was prepared using trimethylammonium octanoate as a catalyst under conditions where the molar ratio of monomer, catalyst, and initiator was 100:1:1. The preparation method includes the following steps:

[0071] Under argon protection, L-LA (2.1765 g, 15 mmol), trimethylammonium octanoate inner salt (C8 catalyst) (0.0304 g, 0.15 mmol), and PPA (0.0202 g, 0.15 mmol) were added to a dry reaction tube. The reaction was magnetically stirred at 100 °C for 10 h. After the reaction, a small sample was taken from the mixture to remove volatiles under vacuum. 1 ¹H NMR showed a monomer conversion of 80%. The remaining reaction solution was rotary evaporated, and the crude product was dissolved in a minimal amount of dichloromethane. Upon addition of this to a cold methanol solution, polymer precipitated. Separation and purification yielded a white PLA powder. 1 H NMR spectrum as shown Figure 2 Its molecular weight (Mn) was determined to be 6840 g / mol by GPC, and its molecular weight distribution was... It is 1.20.

[0072] Example 5

[0073] Poly-L-lactide (PLLA) was prepared with trimethylammonium pentanoate as catalyst at a monomer, catalyst and initiator molar ratio of 100:1:1, the preparation method comprising the following steps:

[0074] L-LA (1.9189 g, 13.3 mmol), trimethylammonium pentanoate (C5 catalyst) (0.0212 g, 0.133 mmol) and PPA (0.018 g, 0.133 mmol) were added into a dry reaction tube under argon protection. The reaction was stirred magnetically at 100°C for 10 h. After the reaction, a small amount of sample was taken from the reaction mixture, and the volatile matter was removed under vacuum. The monomer conversion was determined by1H NMR. 1 The monomer conversion was 88% as determined by1H NMR. The remaining reaction liquid was rotary evaporated, and the obtained crude product was dissolved in a minimum amount of dichloromethane, and then a cold methanol solution was added, and the polymer precipitated. The white powder PLA was obtained after separation and purification. The molecular weight Mn of the polymer was 6685 g / mol, and the molecular weight distribution was 1.11.

[0075] Example 6

[0076] Poly-p-dioxanone (PPDO) was prepared with trimethylammonium pentanoate as catalyst at a monomer, catalyst and initiator molar ratio of 50:1:1, the preparation method comprising the following steps:

[0077] PDO (0.8338 g, 8.17 mmol), trimethylammonium pentanoate (C5 catalyst) (0.0259 g, 0.163 mmol) and PPA (0.0222 g, 0.163 mmol) were added into a dry reaction tube under argon protection. The reaction was stirred magnetically at 100°C for 24 h. After the reaction, a small amount of sample was taken from the reaction mixture, and the volatile matter was removed under vacuum. The monomer conversion was determined by1H NMR. 1 The monomer conversion was 78% as determined by1H NMR. The remaining reaction liquid was rotary evaporated, and the obtained crude product was dissolved in a minimum amount of dichloromethane, and then a cold methanol solution was added, and the polymer precipitated. The light yellow powder PPDO was obtained after separation and purification. The molecular weight Mn of the polymer was 3344 g / mol, and the molecular weight distribution 1 H NMR spectrum was as shown in Figure 3 , and the molecular weight Mn was 3344 g / mol, and the molecular weight distribution was 1.59.

[0078] Example 7

[0079] Poly-p-dioxanone (PPDO) was prepared with trimethylammonium pentanoate as catalyst at a monomer, catalyst and initiator molar ratio of 50:1:1, the preparation method comprising the following steps:

[0080] Under argon protection, PDO (0.8963 g, 8.78 mmol), trimethylammonium nonanoate inner salt (C8 catalyst) (0.0351 g, 0.175 mmol) and PPA (0.0238 g, 0.175 mmol) were added into a dry reaction tube. The reaction was stirred magnetically at 100 °C for 24 h. After the reaction, a small amount of sample was taken from the reaction mixture and the volatile matter was removed under vacuum. The monomer conversion was determined by1H NMR to be 75%. The remaining reaction solution was rotary evaporated. The crude product was dissolved in a minimum amount of dichloromethane and added into a cold methanol solution. The polymer precipitated. The yellowish powder was separated and purified to obtain PPDO. The molecular weight of the polymer was determined by GPC to be Mn= 4072 g / mol with a molecular weight distribution of Mw / Mn= 1.49. 1 The1H NMR spectrum is shown in Fig. 2. 1 The1H NMR spectrum is shown in Fig. 2. Figure 3

[0081] Example 8

[0082] The difference from Example 7 is that the catalyst used is trimethylammonium undecanoate inner salt (C11 catalyst, x is 10) and the monomer conversion is 60%. The molecular weight of the polymer was determined by GPC to be Mn= 3025 g / mol with a molecular weight distribution of Mw / Mn= 1.53.

[0083] Example 9

[0084] PGA was prepared using trimethylammonium nonanoate inner salt as catalyst under the condition of a monomer, catalyst and initiator molar ratio of 50:1:1. The preparation method comprises the following steps:

[0085] Under argon protection, GA (0.9892 g, 8.52 mmol), trimethylammonium nonanoate inner salt (C8 catalyst) (0.0343 g, 0.170 mmol) and PPA (0.0236 g, 0.173 mmol) were added into a dry reaction tube. The reaction was stirred magnetically at 100 °C for 3 h. After the reaction, the reaction mixture was taken out and crushed in a mortar. It was wrapped with filter paper. A Soxhlet extractor was used to extract the product with ethyl acetate for 24 h. The product was dried under vacuum to remove the solvent and pure PGA was obtained. The conversion was calculated to be 94%. The intrinsic viscosity of the polymer was 0.12 dL / g.

[0086] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application. However, these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.​​​

Claims

1. The application of a catalyst in the homopolymerization of lactones or cyclic carbonates, characterized in that, The catalyst has the following structure: (CH3)3N + (CH2) x COO － , where x is an integer between 3 and 10.

2. The application of the catalyst according to claim 1 in the homopolymerization reaction of lactones or cyclic carbonates, characterized in that, This catalyst is used to catalyze the homopolymerization of trimethylene carbonate (TMC), glycolide (GA), lactide (L-LA), or dioxane (PDO).

3. A method for preparing cyclic lactone homopolymers or cyclic carbonate homopolymers, characterized in that, Using lactones or cyclic carbonates as monomers, with (CH3)3N + (CH2) x COO － Using ROH as a catalyst, bulk polymerization is carried out in the presence of the initiator to obtain cyclic lactone homopolymers or cyclic carbonate homopolymers. The reaction equations are as follows: Wherein, the cyclic carbonate is trimethylene carbonate (TMC), the lactone is glycolide (GA), lactide (L-LA), or p-dioxanone (PDO), x is an integer from 3 to 10, and R is a hydrocarbon group.

4. The method for preparing cyclic lactone homopolymers or cyclic carbonate homopolymers according to claim 3, characterized in that, R is a hydrocarbon group having 1-10 carbons.

5. The method for preparing cyclic lactone homopolymers or cyclic carbonate homopolymers according to claim 3, characterized in that, No solvent is added during the bulk polymerization reaction, and the reaction time is 9 minutes to 48 hours.

6. The method for preparing cyclic lactone homopolymers or cyclic carbonate homopolymers according to claim 4, characterized in that, The initiator is 3-phenylpropanol.

7. The method for preparing cyclic lactone homopolymers or cyclic carbonate homopolymers according to claim 3, characterized in that, The molar ratio of the initiator to the monomer is 1:15 to 50.

8. The method for preparing cyclic lactone homopolymers or cyclic carbonate homopolymers according to claim 3, characterized in that, The molar ratio of the catalyst to the monomer is 1:50 to 500.

9. The method for preparing cyclic lactone homopolymers or cyclic carbonate homopolymers according to claim 3, characterized in that, The temperature for bulk polymerization is 70–150°C.

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