Catalyst compositions, polylactide, their preparation methods and applications

Abstract

This invention relates to the field of polymer technology, and discloses a catalyst composition, polylactide, its preparation method, and its applications. The catalyst composition of this invention contains a zinc complex and a hydroxyl-containing compound. When the catalyst composition provided by this invention is used for the ring-opening polymerization of lactide to prepare polylactide, it not only exhibits high catalytic activity, but also produces a polymer with a high molecular weight, adjustable molecular weight, and a narrow molecular weight distribution.

Description

Technical Field

[0001] This invention relates to the field of polymer technology, specifically to a catalyst composition, polylactide, its preparation method, and its application. Background Technology

[0002] Polylactic acid (PLA) is a polyester-based biodegradable material with excellent biodegradability, making it widely used in the manufacture of tableware, films, fibers, clothing, automotive parts, and disposable containers. This helps address the environmental pollution problems caused by petrochemical resources. Furthermore, PLA possesses good biocompatibility, non-toxicity, and adjustable degradation characteristics, meeting the requirements for pharmaceutical polymer materials. It shows broad application prospects in fracture internal and external fixation materials, surgical sutures, tissue engineering scaffold materials, and drug sustained-release and controlled-release carrier materials.

[0003] Early methods for synthesizing polyesters primarily involved condensation reactions of acidic and alcoholic compounds. However, the resulting polymers exhibited uncontrollable structures, potentially being linear, branched, or cyclic, with excessively wide molecular weight distributions, low molecular weights, and difficulty in controlling molecular weight, ultimately leading to poor mechanical properties. To improve the overall performance of polymers, recent research on polyester synthesis has focused on developing catalysts for coordination polymerization to initiate ring-opening polymerization of cyclic esters to prepare polyester polymers. Compared to the aforementioned condensation reaction methods, ring-opening polymerization offers the following advantages: First, the molecular weight of the polyester can be precisely controlled, and the molecular weight distribution is narrower; second, no water is generated during ring-opening polymerization, resulting in polymers with higher molecular weights; and third, selective polymerization of chiral monomers can be achieved through catalyst selection.

[0004] Catalyst systems used in the coordination ring-opening polymerization of lactones mainly include complexes of stannous octoate, aluminum, calcium, magnesium, zinc, titanium, and Group IIIB metal complexes. Stannous octoate is currently recognized as a relatively effective catalyst, exhibiting high catalytic activity, requiring only a small amount of catalyst, and capable of producing high molecular weight polymers. Its drawback is that it can only undergo high-temperature bulk polymerization, and its conversion rate is only around 50% at the highest molecular weight. To improve the conversion rate, it is necessary to reduce the molecular weight. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low catalytic activity and uncontrollable molecular weight in existing technologies, and to provide a catalyst composition, polylactide, its preparation method, and its applications. When the catalyst composition provided by this invention is used in the ring-opening polymerization of lactide to prepare polylactide, it not only exhibits high catalytic activity, but also produces a polymer with a high molecular weight, adjustable molecular weight, and a narrow molecular weight distribution.

[0006] In conventional technologies, the addition of hydroxyl-containing compounds to conventional catalysts during the polymerization of lactide monomers often leads to catalyst deactivation, thereby terminating the polymerization chain growth reaction. However, the inventors of this invention, through in-depth research, have discovered that when a hydroxyl-containing compound is added to the zinc complex with the specific structure described in this invention, it can still catalyze polymer chain growth normally without causing polymerization termination. In the polymerization of lactide monomers, the metal complex acts as a catalyst, while the hydroxyl-containing compound acts as a chain transfer agent. That is, the hydroxyl-containing compound can undergo active chain transfer with the initiation center, thereby continuously growing the polymer chain. The apparent effect is that one complex molecule can initiate the growth of a macromolecular chain by 1 to 1000 times. Therefore, the catalytic efficiency is very high, the conversion rate of the polymerization reaction is high, and it exhibits "undying" polymerization characteristics. Utilizing this, the polymer molecular weight can be adjusted within a wide range by controlling the amount of hydroxyl-containing compound added. Simultaneously, the addition of the hydroxyl-containing compound also results in an ideal molecular weight distribution for the polymer.

[0007] Therefore, a first aspect of the present invention provides a catalyst composition comprising a zinc complex of formula (I) and a hydroxyl-containing compound.

[0008]

[0009] In formula (I), R1 is a C1-C6 alkyl, halogen, or aryl group whose hydrogen atom is substituted or unsubstituted by at least one group selected from halogens and C1-C6 alkyl groups. 12 The aryl group; R2 is a C1-C6 alkyl group, a halogen, or a C6-C6 alkyl group whose hydrogen atom is substituted or unsubstituted by at least one group selected from halogens and C1-C6 alkyl groups. 12 R3 is an aryl group; R3 is a C1-C6 alkyl group.

[0010] Preferably, the alkyl group of C1-C6 is methyl, ethyl, or propyl.

[0011] Preferably, the halogen is fluorine, chlorine, bromine or iodine, more preferably chlorine or bromine.

[0012] Preferably, R1 is methyl, ethyl, propyl, chloro, bromine, phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl, or propylphenyl, more preferably methyl, chloro, bromine, phenyl, chlorophenyl, or methylphenyl.

[0013] Preferably, R2 is phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl, propylphenyl, naphthyl or methylnaphthyl, more preferably phenyl, chlorophenyl, methylphenyl, naphthyl or methylnaphthyl; preferably, R3 is methyl.

[0014] Preferably, the hydroxyl-containing compound is an alcohol and / or a phenolic compound.

[0015] Preferably, the hydroxyl-containing compound is a substituted or unsubstituted C1-C5 straight-chain or branched fatty alcohol, or a C6-C5... 20 At least one of aromatic alcohols, C4-C6 alkanolamines, and phenols, wherein the substituted group is selected from C1-C6 alkyl, C1-C6 alkoxy, or C6-C6 alkyl groups. 10 Aryl groups.

[0016] Preferably, the hydroxyl-containing compound is at least one selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, triethanolamine, diphenylmethanol, triphenylmethanol, benzyl alcohol, and phenol.

[0017] Preferably, the molar ratio of the zinc complex to the hydroxyl-containing compound is 1:0.01-1000, more preferably 1:0.1-700, and even more preferably 1:0.5-500.

[0018] According to a second aspect of the present invention, a method for preparing polylactide is provided, wherein the method comprises: a step of solution polymerization of lactide monomers in the presence of a zinc complex of formula (I) and a hydroxyl-containing compound.

[0019]

[0020] In formula (I), R1 is a C1-C6 alkyl, halogen, or aryl group whose hydrogen atom is substituted or unsubstituted by at least one group selected from halogens and C1-C6 alkyl groups. 12 The aryl group; R2 is a C1-C6 alkyl group, a halogen, or a C6-C6 alkyl group whose hydrogen atom is substituted or unsubstituted by at least one group selected from halogens and C1-C6 alkyl groups. 12 R3 is an aryl group; R3 is a C1-C6 alkyl group.

[0021] Preferably, the alkyl group of C1-C6 is methyl, ethyl, or propyl.

[0022] Preferably, the halogen is fluorine, chlorine, bromine or iodine, more preferably chlorine or bromine.

[0023] Preferably, R1 is methyl, ethyl, propyl, chloro, bromine, phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl, or propylphenyl, more preferably methyl, chloro, bromine, phenyl, chlorophenyl, or methylphenyl.

[0024] Preferably, R2 is phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl, propylphenyl, naphthyl or methylnaphthyl, more preferably phenyl, chlorophenyl, methylphenyl, naphthyl or methylnaphthyl.

[0025] Preferably, R3 is a methyl group.

[0026] Preferably, the hydroxyl-containing compound is an alcohol and / or a phenolic compound.

[0027] Preferably, the hydroxyl-containing compound is a substituted or unsubstituted C1-C5 straight-chain or branched fatty alcohol, or a C6-C5... 20 At least one of aromatic alcohols, C4-C6 alkanolamines, and phenols, wherein the substituted group is selected from C1-C6 alkyl, C1-C6 alkoxy, or C6-C6 alkyl groups. 10 Aryl.

[0028] Preferably, the hydroxyl-containing compound is at least one selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, triethanolamine, diphenylmethanol, triphenylmethanol, benzyl alcohol, and phenol.

[0029] Preferably, the molar ratio of the zinc complex to the hydroxyl-containing compound is 1:0.01-1000, more preferably 1:0.1-700, and even more preferably 1:0.5-500.

[0030] Preferably, the molar ratio of the hydroxyl-containing compound to the lactide monomer can be 1:1-20000, more preferably 1:20-19000, more preferably 1:50-18000, more preferably 1:100-16000, more preferably 1:200-15000, and even more preferably 500-5000.

[0031] Preferably, the molar ratio of the zinc complex shown in formula (I) to the lactide monomer is 1:1-10000, more preferably 1:50-5000, and even more preferably 1:100-2000.

[0032] Preferably, the conditions for solution polymerization include: a reaction temperature of 10-160℃, more preferably 25-100℃; and a reaction time of 0.02-56h, more preferably 3-52h.

[0033] According to a third aspect of the present invention, a polylactide prepared by the method of the present invention is provided.

[0034] According to a fourth aspect of the invention, the use of the catalyst composition of the invention in the preparation of polylactide is provided.

[0035] Through the above technical solutions, the catalyst composition and its application, as well as the polylactide and its preparation method provided by the present invention, achieve the following beneficial effects:

[0036] The catalyst composition provided by this invention, comprising a zinc complex with a specific structure and a hydroxyl-containing compound, can efficiently catalyze the ring-opening polymerization of lactide at a low concentration of metal catalyst, exhibiting high catalytic efficiency and high conversion rate of the polymerization reaction. Simultaneously, during the catalytic process, the hydroxyl-containing compound undergoes active chain transfer with the initiation center, thereby enabling the polylactide chain to continuously grow, exhibiting "undying" polymerization characteristics and a molecular weight distribution close to 1, and obtaining polylactide with controllable molecular weight. Detailed Implementation

[0037] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0038] According to a first aspect of the present invention, a catalyst composition is provided, wherein the catalyst composition comprises a zinc complex of formula (I) and a hydroxyl-containing compound.

[0039]

[0040] In formula (I), R1 is a C1-C6 alkyl, halogen, or aryl group whose hydrogen atom is substituted or unsubstituted by at least one group selected from halogens and C1-C6 alkyl groups. 12 The aryl group; R2 is a C1-C6 alkyl group, a halogen, or a C6-C6 alkyl group whose hydrogen atom is substituted or unsubstituted by at least one group selected from halogens and C1-C6 alkyl groups. 12 R3 is an aryl group; R3 is a C1-C6 alkyl group.

[0041] In this invention, the C1-C6 alkyl refers to a straight-chain alkyl, branched alkyl, or cycloalkyl with 1-6 carbon atoms.

[0042] Examples of C1-C6 alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, etc.

[0043] The C6-C 12 The aryl group refers to an aryl group with 6-12 carbon atoms.

[0044] As the C6-C 12 Examples of aryl groups include phenyl, benzyl, and phenethyl.

[0045] According to the present invention, preferably, the alkyl group of C1-C6 is methyl, ethyl or propyl.

[0046] According to the present invention, preferably, the halogen is fluorine, chlorine, bromine or iodine, more preferably chlorine or bromine, and even more preferably chlorine.

[0047] The R1 group is preferably composed of methyl, ethyl, propyl, chlorine, bromine, phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl, or propylphenyl, and more preferably methyl, chlorine, bromine, phenyl, chlorophenyl, or methylphenyl.

[0048] The R2 group is preferably composed of phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl, propylphenyl, naphthyl or methylnaphthyl, and more preferably phenyl, chlorophenyl, methylphenyl, naphthyl or methylnaphthyl.

[0049] The R3 group is preferably composed of methyl, ethyl, propyl, butyl, pentyl or hexyl, more preferably methyl, ethyl or propyl, and particularly preferably methyl.

[0050] According to the present invention, the hydroxyl-containing compound can be an alcohol and / or a phenolic compound. Preferably, the hydroxyl-containing compound is a substituted or unsubstituted C1-C5 straight-chain or branched fatty alcohol, or a C6-C5... 20 At least one of aromatic alcohols, C4-C6 alkanolamines, and phenols, wherein the substituted group is selected from C1-C6 alkyl, C1-C6 alkoxy, or C6-C6 alkyl groups. 10 Aryl.

[0051] The hydroxyl-containing compound is preferably at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, triethanolamine, diphenylmethanol, triphenylmethanol, benzyl alcohol, and phenol; particularly preferably, the hydroxyl-containing compound is at least one of isopropanol, benzyl alcohol, diphenylmethanol, triphenylmethanol, and triethanolamine.

[0052] According to the present invention, the contents of the zinc complex and the hydroxyl-containing compound can vary within a wide range. For example, the molar ratio of the zinc complex to the hydroxyl-containing compound can be 1:0.01-1000, preferably 1:0.1-700, more preferably 1:0.5-500, further preferably 1:1-50, and particularly preferably 1:1-10.

[0053] According to the present invention, a catalyst composition comprising a zinc complex with a specific structure and a hydroxyl-containing compound can efficiently catalyze the ring-opening polymerization of lactide at a low concentration of metal catalyst, with high catalytic efficiency and high conversion rate of polymerization reaction; at the same time, during the catalytic process, the hydroxyl-containing compound undergoes active chain transfer with the initiation center, thereby enabling the polylactide chain to grow continuously, exhibiting "undying" polymerization characteristics and a molecular weight distribution close to 1, and obtaining polylactide with controllable molecular weight.

[0054] According to a second aspect of the present invention, a method for preparing polylactide is provided, wherein the method comprises: a step of solution polymerization of lactide monomers in the presence of a zinc complex of formula (I) and a hydroxyl-containing compound.

[0055]

[0056] In formula (I), R1 is a C1-C6 alkyl, halogen, or aryl group whose hydrogen atom is substituted or unsubstituted by at least one group selected from halogens and C1-C6 alkyl groups. 12 The aryl group; R2 is a C1-C6 alkyl group, a halogen, or a C6-C6 alkyl group whose hydrogen atom is substituted or unsubstituted by at least one group selected from halogens and C1-C6 alkyl groups. 12 R3 is an aryl group; R3 is a C1-C6 alkyl group.

[0057] In this invention, the combined use of zinc complex and hydroxyl-containing compound reduces the amount of zinc complex required. A small amount of zinc complex can catalyze the production of high molecular weight polylactide with high catalytic efficiency. Simultaneously, during the catalytic process, the hydroxyl-containing compound undergoes active chain transfer with the initiation center, thereby enabling the polylactide chain to continuously grow, exhibiting "undying" polymerization characteristics and a molecular weight distribution close to 1, thus obtaining polylactide with controllable molecular weight.

[0058] In this invention, "lactide monomer" refers to L-lactide, D-lactide, and L,D-lactide.

[0059] Furthermore, the R1, R2, and R3 groups are as described above and will not be repeated here.

[0060] The preparation method of the polylactide of the present invention using a zinc complex and a hydroxyl-containing compound (i.e., the catalyst composition of the present invention) will be described in detail below.

[0061] According to the present invention, the amounts of the zinc complex and the hydroxyl-containing compound can vary within a wide range. For example, the molar ratio of the zinc complex to the hydroxyl-containing compound can be 1:0.01-1000. To further improve catalytic efficiency, preferably, the molar ratio of the zinc complex to the hydroxyl-containing compound is 1:0.1-700; more preferably, the molar ratio is 1:0.5-500; even more preferably, the molar ratio is 1:1-50; and particularly preferably, the molar ratio is 1:1-10.

[0062] To further improve catalytic efficiency, preferably, the molar ratio of the hydroxyl-containing compound to the lactide monomer is 1:1-20000, more preferably 1:20-19000, more preferably 1:50-18000, more preferably 1:100-16000, more preferably 1:200-15000, and even more preferably 500-5000.

[0063] To further improve catalytic efficiency, preferably, the molar ratio of the zinc complex shown in formula (I) to the lactide monomer is 1:1-10000, more preferably 1:50-5000, and even more preferably 1:100-2000.

[0064] In this invention, there is no particular limitation on the way the zinc complex and the hydroxyl-containing compound are added. They can be added separately during the reaction, or they can be added simultaneously, or they can be prepared in advance and added simultaneously by the following method: Under dry and rapid stirring conditions, the organic solvent containing the zinc complex is slowly added dropwise to the organic solvent containing the hydroxyl-containing compound, and the resulting mixture is vacuum filtered to obtain the catalyst composition.

[0065] The organic solvent containing the zinc complex can be the same as or different from the organic solvent containing the hydroxyl-containing compound, but preferably both are the same. Furthermore, the solvent used in solution polymerization can also be used as the organic solvent.

[0066] According to the present invention, the solvent used in the solution polymerization can be an organic solvent, preferably at least one of substituted or unsubstituted alkanes, substituted or unsubstituted benzenes and substituted or unsubstituted ethers.

[0067] In a preferred embodiment of the present invention, the solvent is at least one selected from pentane, hexane, benzene, chlorobenzene, toluene, tetrahydrofuran, diethyl ether, and dichloromethane; more preferably, the solvent is one or more selected from toluene, tetrahydrofuran, and dichloromethane.

[0068] According to the present invention, preferably, the solution polymerization conditions include a reaction temperature of 10-160°C and a reaction time of 0.02-56 h; more preferably, the solution polymerization conditions include a reaction temperature of 25-100°C and a reaction time of 3-52 h. Furthermore, to avoid the influence of water and oxygen on the catalytic activity of the catalyst, the reaction of the present invention is preferably carried out under anhydrous and oxygen-free conditions.

[0069] After the reaction is complete, post-treatment is performed to obtain polylactide. The post-treatment may include adding the mixed liquid after the reaction to an ethanol solution of hydrochloric acid with a volume concentration of 5-20 v% (preferably 8-12 v%) to terminate the reaction, then precipitating it in ethanol, filtering to obtain a white solid, and drying the white solid at 30-50℃ for 36-60 h to obtain polylactide.

[0070] According to a third aspect of the present invention, a method for preparing polylactide according to the second aspect of the present invention is provided, which yields polylactide.

[0071] In the preparation method of this invention, the combined use of zinc complex and hydroxyl-containing compound reduces the amount of zinc complex required. A small amount of zinc complex can catalyze the production of high molecular weight polylactide with high catalytic efficiency. Simultaneously, during the catalytic process, the hydroxyl-containing compound undergoes active chain transfer with the initiation center, thereby enabling the polylactide chain to continuously grow, exhibiting "undying" polymerization characteristics and a molecular weight distribution close to 1, thus obtaining polylactide with controllable molecular weight.

[0072] Specifically, the number-average molecular weight of the polylactide can be 0.1 million to 150,000, preferably 0.35 million to 120,000; the molecular weight distribution is 1 to 1.5, preferably 1 to 1.3.

[0073] According to a fourth aspect of the invention, the use of the catalyst composition of the first aspect of the invention in the preparation of polylactide is provided.

[0074] The present invention will be described in detail below through embodiments, but the present invention is not limited to the following embodiments.

[0075] In the following examples, the room temperature is approximately "25°C";

[0076] (1) Polymer conversion rate: The conversion rate was measured using a Swiss Bruker Avance 400 nuclear magnetic resonance spectrometer. The test conditions were: the solvent was deuterated chloroform and the test temperature was room temperature.

[0077] (2) Molecular weight and distribution of polymer: The molecular weight was determined by a Shimadzu LC-20A liquid gel permeation chromatograph (GPC); the test conditions were: chloroform solvent, test temperature 25℃, and flow rate 1mL / min.

[0078] (3) Elemental analysis of metal complexes: Elemental analysis was performed using an Elementar Vario EL elemental analyzer;

[0079] The ligand structure used in the embodiments of the present invention is shown in formula (II), and the preparation method is as follows:

[0080]

[0081] Weigh 10g of methyl salicylate, 8ml of 85% hydrazine hydrate and 20ml of anhydrous ethanol, add them to a round-bottom flask and heat under reflux for 9 hours. Let stand overnight, and a large amount of white precipitate will precipitate. Filter the precipitate, wash it with ethanol and dry it to obtain a white powdery solid (II-1).

[0082] Add 10 mmol (II-1), 20 ml THF, 20 ml distilled water, 5 mmol Na2CO3 and 10 mmol R1COCl to a round-bottom flask, reflux at room temperature for 4 h, distill under reduced pressure, recrystallize with anhydrous ethanol to obtain solid (II-2).

[0083] 5 mmol of compound (II-2) and 27 mmol of phosphorus oxychloride were added to a round-bottom flask and heated under reflux for 3 h. After cooling to room temperature, the mixture was slowly poured into ice water while stirring to obtain a flocculent precipitate. The precipitate was filtered and recrystallized from anhydrous ethanol to obtain solid (II-3).

[0084] Compound (II-3) and R2NHCOCH2Cl were weighed in a molar ratio of 1:1 and dissolved in DMF. K2CO3 (molar ratio of K2CO3 to compound (II-3) was added to the DMF solution containing compound (II-3) (molar ratio of K2CO3 to compound (II-3) was 1:1.1). The mixture was stirred at 90 °C for 0.5 h. The DMF solution containing R2NHCOCH2Cl was slowly added dropwise. After the addition was complete, a small amount of KI was added. The mixture was stirred at 100-110 °C for 5 h. After cooling, the reaction mixture was poured into distilled water and stirred at room temperature for 5 h. The mixture was then filtered, washed with water and dried. The mixture was recrystallized with a 1:1 mixture of ethyl acetate and ethanol to obtain the desired ligand. The ligand was dried under vacuum and stored for later use.

[0085] in,

[0086] Ligand A (in formula (II), R1 is methyl and R2 is phenyl), has the molecular formula C 17 H 15 N3O3 (measured values): C, 66.01 (66.01); H, 4.89 (4.88); N, 13.58 (13.58); O, 15.52 (15.53).

[0087] Ligand B (in formula (II), R1 is chlorine and R2 is benzyl), has the molecular formula C 17H 14 ClN3O3 (measured values): C, 59.40 (59.38); H, 4.10 (4.11); N, 12.22 (12.21); O, 13.96 (13.95).

[0088] Ligand C (in formula (II), R1 is phenyl and R2 is methylnaphthalene), has the molecular formula C 27 H 21 N3O3 (measured values): C, 74.47 (74.45); H, 4.86 (4.87); N, 9.65 (9.65); O, 11.02 (11.01).

[0089] Preparation Example 1

[0090] Preparation of zinc complex A (in formula (I), R1 is methyl, R2 is phenyl, and R3 is methyl)

[0091] Ligand A has the structure shown in formula (II), where R1 is methyl and R2 is phenyl. 1.0 mmol of ligand A was weighed, added to ethanol, and the pH was adjusted to 8 with dilute NaOH to completely dissolve the ligand. An ethanol solution containing an equimolar amount of Zn(CH3COO)2·2H2O was added, resulting in a white precipitate. The mixture was stirred at room temperature for 5 hours, centrifuged, washed 2-3 times with anhydrous ethanol, and dried under vacuum to obtain zinc complex A in 43% yield.

[0092] The elemental analysis data of the product are: C 19 H 18 N3O5Zn (measured values): C, 52.61 (52.60); H, 4.18 (4.19); N, 9.69 (9.68); O, 18.44 (18.45).

[0093] Preparation Example 2

[0094] Preparation of zinc metal complex B (in formula (I), R1 is chlorine, R2 is benzyl, and R3 is methyl)

[0095] Ligand B has the structure shown in formula (II), where R1 is chlorine and R2 is benzyl. 1.0 mmol of ligand A was weighed, added to ethanol, and the pH was adjusted to 8 with dilute NaOH to completely dissolve the ligand. An ethanol solution containing an equimolar amount of Zn(CH3COO)2·2H2O was added, and a white precipitate appeared. The mixture was stirred at room temperature for 5 h, centrifuged, washed 2-3 times with anhydrous ethanol, and dried under vacuum to obtain zinc complex A with a yield of 41%.

[0096] The elemental analysis data of the product are: C 19 H 17N3O5Zn (measured values): C, 48.74 (48.75); H, 3.66 (3.68); N, 8.97 (8.96); O, 17.09 (17.09).

[0097] Preparation Example 3

[0098] Preparation of zinc metal complex C (in formula (I), R1 is phenyl, R2 is methyl phenol, and R3 is methyl)

[0099] Ligand C has the structure shown in formula (II), where R1 is phenyl and R2 is methylnaphthalene. 1.0 mmol of ligand A was weighed, added to ethanol, and the pH was adjusted to 8 with dilute NaOH to completely dissolve the ligand. An ethanol solution containing an equimolar amount of Zn(CH3COO)2·2H2O was added, resulting in a white precipitate. The mixture was stirred at room temperature for 5 hours, centrifuged, washed 2-3 times with anhydrous ethanol, and dried under vacuum to obtain zinc complex A in 41% yield.

[0100] The elemental analysis data of the product are: C 29 H 24 N3O5Zn (measured values): C, 62.21 (62.21); H, 4.32 (4.33); N, 7.50 (7.49); O, 14.29 (14.30).

[0101] Preparation Example 4

[0102] Preparation of zinc metal complex D (in formula (I), R1 is phenyl, R2 is methylnaphthalene, and R3 is ethyl)

[0103] The preparation was carried out according to Preparation Example 1, except that Zn(CH3COO)2·2H2O was replaced with zinc propionate to obtain zinc metal complex D.

[0104] Example 1

[0105] At room temperature, 10 μmol of zinc complex A, 10 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free conditions. 40 mmol of L-lactide monomer was added, and the mixture was stirred at 70 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0106] The conversion rate of nuclear magnetic resonance testing was 91%.

[0107] GPC analysis determined the number-average molecular weight M of polylactide. n It is 0.35 million, and the molecular weight distribution is M. w / M nIt is 1.26.

[0108] Example 2

[0109] At room temperature, 10 μmol of zinc complex A, 10 μmol of benzyl alcohol, and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free solvent. 20 mmol of L,D-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle, filtered, and a white solid was obtained. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0110] The conversion rate of nuclear magnetic resonance testing was 91%.

[0111] GPC analysis determined the number-average molecular weight M of polylactide. n It is 0.41 million, and the molecular weight distribution is M. w / M n It is 1.24.

[0112] Example 3

[0113] At room temperature, 10 μmol of zinc complex B, 10 μmol of benzyl alcohol, and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free conditions. 10 mmol of L-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0114] The conversion rate of nuclear magnetic resonance testing is 95%.

[0115] GPC analysis determined the number-average molecular weight M of polylactide. n It is 108,000, and the molecular weight distribution is M. w / M n It is 1.18.

[0116] Example 4

[0117] At room temperature, 10 μmol of zinc complex C, 100 μmol of benzyl alcohol, and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free conditions. 10 mmol of L,D-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0118] The conversion rate of nuclear magnetic resonance testing is 95%.

[0119] GPC analysis determined the number-average molecular weight M of polylactide. n It is 49,000, and the molecular weight distribution is M. w / M n It is 1.20.

[0120] Example 5

[0121] At room temperature, 10 μmol of zinc complex B, 10 μmol of benzyl alcohol, and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free conditions. 5 mmol of L-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0122] The conversion rate of nuclear magnetic resonance testing was 92%.

[0123] GPC analysis determined the number-average molecular weight M of polylactide. n It is 67,000, and the molecular weight distribution is M. w / M n It is 1.23.

[0124] Example 6

[0125] At room temperature, 10 μmol of zinc complex C, 200 μmol of benzyl alcohol, and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free conditions. 10 mmol of L-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0126] The conversion rate of nuclear magnetic resonance testing was 94%.

[0127] GPC analysis determined the number-average molecular weight M of polylactide. n It is 0.88 million, and the molecular weight distribution is M. w / M n It is 1.14.

[0128] Example 7

[0129] At room temperature, 10 μmol of zinc complex A, 500 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free solvent. 10 mmol of L,D-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0130] The conversion rate of nuclear magnetic resonance testing is 95%.

[0131] GPC analysis determined the number-average molecular weight M of polylactide. n It is 0.43 million, and the molecular weight distribution is M. w / M n It is 1.13.

[0132] Example 8

[0133] At room temperature, 10 μmol of zinc complex C, 10 μmol of benzyl alcohol, and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free conditions. 1 mmol of L-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0134] The conversion rate of nuclear magnetic resonance testing is 90%.

[0135] GPC analysis determined the number-average molecular weight M of polylactide. n It is 14,200, and the molecular weight distribution is M. w / M n It is 1.25.

[0136] Example 9

[0137] At room temperature, 10 μmol of zinc complex A, 10 μmol of isopropanol, and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free conditions. 10 mmol of L-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0138] The conversion rate of nuclear magnetic resonance testing is 95%.

[0139] GPC analysis determined the number-average molecular weight M of polylactide. n It is 101,000, and the molecular weight distribution is M.w / M n It is 1.20.

[0140] Example 10

[0141] At room temperature, 10 μmol of zinc complex B, 0.5 μmol of benzyl alcohol, 0.5 μmol of diphenylmethanol and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free conditions. 5 mmol of L,D-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution with a volume concentration of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0142] The conversion rate of nuclear magnetic resonance testing was 91%.

[0143] GPC analysis determined the number-average molecular weight M of polylactide. n It is 49,000, and the molecular weight distribution is M. w / M n It is 1.23.

[0144] Example 11

[0145] The procedure was carried out according to Example 1, except that zinc complex A was replaced with zinc complex D, and polylactide solid was obtained in the same manner.

[0146] The conversion rate of nuclear magnetic resonance testing was 89%.

[0147] GPC analysis determined the number-average molecular weight M of polylactide. n It is 0.33 million, and the molecular weight distribution is M. w / M n It is 1.25.

[0148] Comparative Example 1

[0149] At room temperature, 10 μmol of zinc complex A and 10 mL of toluene solvent were added to a 20 mL polymerization flask that had been treated with anhydrous and oxygen-free conditions. 1 mmol of L-lactide monomer was added, and the mixture was stirred at 100 °C for 48 h. The reaction was then terminated by adding an ethanol solution of 10 v% hydrochloric acid. The reaction solution was poured into ethanol to settle and filtered to obtain a white solid. The white solid was dried in a vacuum drying oven at 40 °C for 48 h to obtain polylactide solid.

[0150] The conversion rate of nuclear magnetic resonance testing was 69%.

[0151] GPC analysis determined the number-average molecular weight M of polylactide. n It is 0.62 million, and the molecular weight distribution is M. w / M nIt is 1.25.

[0152] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst composition, characterized in that, The catalyst composition contains a zinc complex of formula (I) and a hydroxyl-containing compound. Equation (I) In formula (I), R1 is a C1-C6 alkyl, halogen or phenyl; R2 is a phenyl, benzyl or naphthyl; R3 is a C1-C6 alkyl.

2. The catalyst composition according to claim 1, wherein, The alkyl groups of C1-C6 are methyl, ethyl, or propyl.

3. The catalyst composition according to claim 1, wherein, The halogen is fluorine, chlorine, bromine or iodine.

4. The catalyst composition according to claim 3, wherein, The halogen is chlorine or bromine.

5. The catalyst composition according to claim 1, wherein, R1 can be methyl, ethyl, propyl, chloro, bromine, or phenyl.

6. The catalyst composition according to claim 5, wherein, R1 can be methyl, chlorine, bromine, or phenyl.

7. The catalyst composition according to claim 1, wherein, R3 is a methyl group.

8. The catalyst composition according to claim 1, wherein, The hydroxyl-containing compounds are alcohols and / or phenols.

9. The catalyst composition according to claim 8, wherein, The hydroxyl-containing compound is a substituted or unsubstituted C1-C5 straight-chain or branched fatty alcohol, or a C6-C5... 20 At least one of aromatic alcohols, C4-C6 alkanolamines, and phenols, wherein the substituted group is selected from C1-C6 alkyl, C1-C6 alkoxy, or C6-C6 alkyl groups. 10 Aryl.

10. The catalyst composition according to claim 8, wherein, The hydroxyl-containing compound is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, triethanolamine, diphenylmethanol, triphenylmethanol, benzyl alcohol, and phenol.

11. The catalyst composition according to any one of claims 1-10, wherein, The molar ratio of the zinc complex to the hydroxyl-containing compound is 1:0.01-1000.

12. The catalyst composition according to claim 11, wherein, The molar ratio of the zinc complex to the hydroxyl-containing compound is 1:0.1-700.

13. The catalyst composition according to claim 12, wherein, The molar ratio of the zinc complex to the hydroxyl-containing compound is 1:0.5-500.

14. A method for preparing polylactide, characterized in that, The preparation method includes: a step of solution polymerization of lactide monomers in the presence of a zinc complex of formula (I) and a hydroxyl-containing compound. Equation (I) In formula (I), R1 is a C1-C6 alkyl, halogen or phenyl; R2 is a phenyl, benzyl or naphthyl; R3 is a C1-C6 alkyl.

15. The method according to claim 14, wherein, The alkyl groups of C1-C6 are methyl, ethyl, or propyl.

16. The method of claim 14, wherein, The halogen is fluorine, chlorine, bromine or iodine.

17. The method according to claim 16, wherein, The halogen is chlorine or bromine.

18. The method according to claim 14, wherein, R1 can be methyl, ethyl, propyl, chloro, bromine, or phenyl.

19. The method according to claim 18, wherein, R1 can be methyl, chlorine, bromine, or phenyl.

20. The method of claim 14, wherein, R3 is a methyl group.

21. The method according to claim 14, wherein, The hydroxyl-containing compounds are alcohols and / or phenols.

22. The method according to claim 21, wherein, The hydroxyl-containing compound is a substituted or unsubstituted C1-C5 straight-chain or branched fatty alcohol, or a C6-C5... 20 At least one of aromatic alcohols, C4-C6 alkanolamines, and phenols, wherein the substituted group is selected from C1-C6 alkyl, C1-C6 alkoxy, or C6-C6 alkyl groups. 10 Aryl.

23. The method according to claim 21, wherein, The hydroxyl-containing compound is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, triethanolamine, diphenylmethanol, triphenylmethanol, benzyl alcohol, and phenol.

24. The method according to any one of claims 14-23, wherein, The conditions for solution polymerization include: a reaction temperature of 10-160℃ and a reaction time of 0.02-56h.

25. The method according to claim 24, wherein, The conditions for solution polymerization include: a reaction temperature of 25-100℃ and a reaction time of 3-52h.

26. The method according to any one of claims 14-23, wherein, The molar ratio of the zinc complex to the hydroxyl-containing compound is 1:0.01-1000.

27. The method according to claim 26, wherein, The molar ratio of the zinc complex to the hydroxyl-containing compound is 1:0.1-700.

28. The method according to claim 27, wherein, The molar ratio of the zinc complex to the hydroxyl-containing compound is 1:0.5-500.

29. The method according to any one of claims 14-23, wherein, The molar ratio of the hydroxyl-containing compound to the lactide monomer is 1:1-20000.

30. The method according to claim 29, wherein, The molar ratio of the hydroxyl-containing compound to the lactide monomer is 1:20-19000.

31. The method according to claim 30, wherein, The molar ratio of the hydroxyl-containing compound to the lactide monomer is 1:50-18000.

32. The method according to claim 31, wherein, The molar ratio of the hydroxyl-containing compound to the lactide monomer is 1:100-16000.

33. The method according to claim 32, wherein, The molar ratio of the hydroxyl-containing compound to the lactide monomer is 1:200-15000.

34. The method according to claim 33, wherein, The molar ratio of the hydroxyl-containing compound to the lactide monomer is 1:500-5000.

35. The method according to any one of claims 14-23, wherein, The molar ratio of the zinc complex shown in formula (I) to the lactide monomer is 1:1-10000.

36. The method according to claim 35, wherein, The molar ratio of the zinc complex shown in formula (I) to the lactide monomer is 1:50-5000.

37. The method according to claim 36, wherein, The molar ratio of the zinc complex shown in formula (I) to the lactide monomer is 1:100-2000.

38. Polylactide prepared by the method of any one of claims 14-37.

39. Use of the catalyst composition according to any one of claims 1-13 in the preparation of polylactide.

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