Catalyst composition, polylactide and preparation method and application thereof

Abstract

The invention relates to the technical field of polymers, and discloses a catalyst composition, polylactide and a preparation method and application thereof. The catalyst composition according to the present invention contains a metal zinc complex and a hydroxyl group-containing compound. When the catalyst composition provided by the invention is used for preparing polylactide through ring-opening polymerization of lactide, the catalytic activity is high, the molecular weight of the obtained polymer is relatively high, the molecular weight is adjustable, and the molecular weight distribution is narrow.

Description

Technical Field

[0001] The present invention relates to the field of polymer technology, and in particular to a catalyst composition, polylactide, and a preparation method and application thereof. Background Art

[0002] Polylactic acid (PLA) is a polyester biodegradable material with excellent biodegradability. Therefore, it is widely used in the production of tableware, films, fibers, clothing, automotive parts and disposable containers, which is conducive to solving the environmental pollution problems caused by petrochemical resources. In addition, polylactic acid also has good biocompatibility, non-toxicity and adjustable degradation, which meets the requirements of medical polymer materials and has broad application prospects in fracture internal and external fixation materials, surgical sutures, tissue engineering scaffold materials and drug sustained release, controlled release carrier materials.

[0003] The early synthesis method of polyester was mainly based on the condensation reaction of acid compounds and alcohol compounds, but the structure of the polymer synthesized by this reaction was uncontrollable, and it might be a linear, branched or cyclic structure, with a too wide molecular weight distribution, low molecular weight and difficult to control, which ultimately led to poor mechanical properties of the polymer. In order to improve the comprehensive performance of the polymer, in recent years, the research on the synthesis of polyester has mainly focused on the development of coordination polymerization catalysts to initiate the ring-opening polymerization of cyclic esters to prepare polyester polymers. Compared with the above-mentioned condensation reaction method, the method of preparing polyester by ring-opening polymerization has the following advantages: first, the molecular weight of the polyester can be precisely controlled, and the molecular weight distribution is narrow; second, no water is generated during the ring-opening polymerization process, and a polymer with a higher molecular weight can be obtained; third, the ring-opening polymerization process can achieve selective polymerization of chiral monomers by selecting the catalyst.

[0004] The catalyst system used for the coordination ring-opening polymerization of lactone mainly includes stannous octoate, metal aluminum, calcium, magnesium, zinc, titanium complexes and IIIB group metal complexes. Stannous octoate is currently recognized as a catalyst with good effect. It has high catalytic activity, low catalyst dosage, and can produce high molecular weight polymers. Its disadvantage is that it can only be polymerized at high temperature, and its conversion rate is only about 50% when the molecular weight reaches the highest. If the conversion rate is to be increased, the molecular weight must be reduced. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of low catalytic activity and uncontrollable molecular weight in the prior art, and to provide a catalyst composition, polylactide and a preparation method and application thereof. When the catalyst composition provided by the present invention is used to prepare polylactide by ring-opening polymerization of lactide, it not only has high catalytic activity, but also has a high molecular weight of the obtained polymer, which can be controlled and has a narrow molecular weight distribution.

[0006] Conventional catalysts in the prior art often cause catalyst deactivation when adding hydroxyl-containing compounds when catalyzing the polymerization of lactide monomers, thereby terminating the polymerization chain growth reaction. However, the inventors of the present invention have found through in-depth research that when the metal zinc complex of the specific structure described in the present invention is added with hydroxyl-containing compounds, it can still catalyze the growth of the polymer chain normally without causing polymerization termination; when the catalyst composition catalyzes the polymerization of lactide monomers, the metal complex plays a catalytic role in the polymerization of lactide monomers, and the hydroxyl-containing compound plays a role as a chain transfer agent, that is, the hydroxyl-containing compound and the initiation center can undergo active chain transfer, thereby causing the polymerization chain to continue to grow, and the apparent effect is that one complex molecule can trigger 1-1000 times of macromolecular chain growth, therefore, the catalytic efficiency is very high, the conversion rate of the polymerization reaction is high, and the "immortal" polymerization characteristics are exhibited; utilizing this point, the molecular weight of the polymer can be adjusted in a wide range by controlling the amount of the hydroxyl-containing compound added, and the addition of the hydroxyl-containing compound also makes the polymer have an ideal molecular weight distribution.

[0007] Therefore, the first aspect of the present invention provides a catalyst composition, wherein the catalyst composition contains a metal zinc complex represented by formula (I) and a hydroxyl-containing compound,

[0008]

[0009] In formula (I), R1 is a C1-C6 alkyl, a halogen, or a hydrogen atom on an aryl group substituted by at least one group selected from halogen, a C1-C6 alkyl, or an unsubstituted C6-C 12 R2 is a C1-C6 alkyl, a halogen, or a hydrogen atom on the aryl group is substituted by at least one group selected from halogen, C1-C6 alkyl or an unsubstituted C6-C 12 R3 is a C1-C6 alkyl group.

[0010] Preferably, the C1-C6 alkyl group 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, chlorine, bromine, phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl or propylphenyl, more preferably methyl, chlorine, bromine, phenyl, chlorophenyl or methylphenyl.

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

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

[0015] Preferably, the hydroxyl-containing compound is a substituted or unsubstituted C1-C5 straight-chain or branched fatty alcohol, a C6-C 20 At least one of an aromatic alcohol, a C4-C6 alcohol amine and a phenol, wherein the substituted group is selected from a C1-C6 alkyl, a C1-C6 alkoxy or a C6-C 10 The aromatic group.

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

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

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

[0019]

[0020] In formula (I), R1 is a C1-C6 alkyl, a halogen, or a hydrogen atom on an aryl group substituted by at least one group selected from halogen, a C1-C6 alkyl, or an unsubstituted C6-C 12 R2 is a C1-C6 alkyl, a halogen, or a hydrogen atom on the aryl group is substituted by at least one group selected from halogen, C1-C6 alkyl or an unsubstituted C6-C 12 R3 is a C1-C6 alkyl group.

[0021] Preferably, the C1-C6 alkyl group 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, chlorine, bromine, phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl or propylphenyl, more preferably methyl, chlorine, bromine, phenyl, chlorophenyl or methylphenyl.

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

[0025] Preferably, R3 is methyl.

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

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

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

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

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

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

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

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

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

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

[0036] The catalyst composition provided by the present invention, which comprises a metal zinc complex of a specific structure and a hydroxyl-containing compound, can efficiently catalyze the ring-opening polymerization reaction of lactide at a relatively low metal catalyst concentration, has a high catalytic efficiency, and a high conversion rate of the polymerization reaction; meanwhile, during the catalytic process, the hydroxyl-containing compound and the initiation center undergo active chain transfer, thereby enabling the polylactide chain to continue to grow, exhibiting an "immortal" polymerization characteristic with a molecular weight distribution close to 1, and being able to obtain polylactide with a controllable molecular weight. DETAILED DESCRIPTION

[0037] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

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

[0039]

[0040] In formula (I), R1 is a C1-C6 alkyl, a halogen, or a hydrogen atom on an aryl group substituted by at least one group selected from halogen, a C1-C6 alkyl, or an unsubstituted C6-C 12 R2 is a C1-C6 alkyl, a halogen, or a hydrogen atom on the aryl group is substituted by at least one group selected from halogen, C1-C6 alkyl or an unsubstituted C6-C 12 R3 is a C1-C6 alkyl group.

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

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

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

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

[0045] According to the present invention, preferably, the C1-C6 alkyl group 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, further preferably chlorine.

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

[0048] As the R2 group, preferably, phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl, propylphenyl, naphthyl or naphthyl may be mentioned, and more preferably, phenyl, chlorophenyl, methylphenyl, naphthyl or naphthyl may be mentioned.

[0049] The R3 group preferably includes a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group or a hexyl group, more preferably a methyl group, an ethyl group or a propyl group, and particularly preferably a methyl group.

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

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

[0052] According to the present invention, the contents of the metal zinc complex and the hydroxyl-containing compound can vary within a wide range. For example, the molar ratio of the metal 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, by using a catalyst composition comprising a metal zinc complex of a specific structure and a hydroxyl-containing compound, the ring-opening polymerization reaction of lactide can be efficiently catalyzed at a relatively low metal catalyst concentration, the catalytic efficiency is very high, and the conversion rate of the polymerization reaction is high; at the same time, during the catalytic process, the hydroxyl-containing compound and the initiation center undergo active chain transfer, thereby allowing the polylactide chain to continue to grow, exhibiting an "immortal" polymerization characteristic with a molecular weight distribution close to 1, and polylactide with controllable molecular weight can be obtained.

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

[0055]

[0056] In formula (I), R1 is a C1-C6 alkyl, a halogen, or a hydrogen atom on an aryl group substituted by at least one group selected from halogen, a C1-C6 alkyl, or an unsubstituted C6-C 12 R2 is a C1-C6 alkyl, a halogen, or a hydrogen atom on the aryl group is substituted by at least one group selected from halogen, C1-C6 alkyl or an unsubstituted C6-C 12 R3 is a C1-C6 alkyl group.

[0057] In the present invention, the metal zinc complex and the hydroxyl-containing compound are used in combination, which reduces the amount of the metal zinc complex used, and a small amount of the metal zinc complex can catalyze the acquisition of high molecular weight polylactide, and the catalytic efficiency is very high; at the same time, during the catalytic process, the hydroxyl-containing compound and the initiation center undergo active chain transfer, thereby allowing the polylactide chain to continue to grow, showing an "immortal" polymerization characteristic and a molecular weight distribution close to 1, and polylactide with controllable molecular weight can be obtained.

[0058] In the present invention, the “lactide monomer” refers to L-lactide, D-lactide, and L,D-lactide.

[0059] In addition, the R1, R2 and R3 groups are as described above and will not be described again here.

[0060] The method for preparing the polylactide of the present invention using the metal zinc complex and the hydroxyl-containing compound (ie, the catalyst composition of the present invention) will be described in detail below.

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

[0062] In order to further improve the 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 further preferably 500-5000.

[0063] In order to further improve the catalytic efficiency, preferably, the molar ratio of the metal zinc complex represented by formula (I) to the lactide monomer is 1:1-10000, preferably 1:50-5000, and more preferably 1:100-2000.

[0064] In the present invention, the method of adding the metal zinc complex and the hydroxyl-containing compound is not particularly limited, and they can be added separately during the reaction, or added simultaneously, or added simultaneously after being prepared in advance according to the following method: under dry and rapid stirring conditions, an organic solvent containing the metal zinc complex is slowly dropped into an organic solvent containing the hydroxyl-containing compound, and the obtained mixture is vacuum filtered to obtain a catalyst composition.

[0065] The organic solvent containing the metal zinc complex and the organic solvent containing the hydroxyl group-containing compound may be the same or different, and preferably they are the same. In addition, the organic solvent used in solution polymerization can be used.

[0066] According to the present invention, the solvent used in the solution polymerization may 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 of pentane, hexane, benzene, chlorobenzene, toluene, tetrahydrofuran, ether and dichloromethane; more preferably, the solvent is one or more of toluene, tetrahydrofuran and dichloromethane.

[0068] According to the present invention, preferably, the conditions of the solution polymerization include: a reaction temperature of 10-160°C and a reaction time of 0.02-56h; more preferably, the conditions of the solution polymerization include: a reaction temperature of 25-100°C and a reaction time of 3-52h. In addition, in order 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 completed, 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 5-20v% (preferably 8-12v%) to terminate the reaction, then precipitating in ethanol, filtering to obtain a white solid, and drying the white solid at 30-50°C for 36-60h to obtain polylactide.

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

[0071] In the preparation method of the present invention, the metal zinc complex and the hydroxyl-containing compound are used in combination, so the amount of the metal zinc complex is reduced, and a small amount of the metal zinc complex can catalyze the acquisition of high molecular weight polylactide, and the catalytic efficiency is very high; at the same time, during the catalytic process, the hydroxyl-containing compound and the initiation center undergo active chain transfer, so that the polylactide chain can continue to grow, showing an "immortal" polymerization characteristic and a molecular weight distribution close to 1, and a polylactide with a controllable molecular weight can be obtained.

[0072] Specifically, the number average molecular weight of the polylactide may be 1,000-150,000, preferably 3,500-120,000; the molecular weight distribution is 1-1.5, preferably 1-1.3.

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

[0074] The present invention will be described in detail below by way of examples, but the present invention is not limited to the following examples.

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

[0076] (1) Conversion rate of polymer: 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 polymers: measured using Shimadzu LC-20A liquid phase gel permeation chromatography (GPC) under the following test conditions: solvent: chloroform, test temperature: 25°C, flow rate: 1 mL / min;

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

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

[0080]

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

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

[0083] Add 5 mmol of compound (II-2) and 27 mmol of phosphorus oxychloride into a round-bottom flask, heat under reflux for 3 h, cool to room temperature and slowly pour into ice water while stirring to obtain a flocculent precipitate. Filter with suction and recrystallize with anhydrous ethanol to obtain a solid (II-3).

[0084] Weigh compound (II-3) and R2NHCOCH2Cl in a molar ratio of 1:1 and dissolve them in DMF respectively. Add K2CO3 (with a molar ratio of 1:1.1 to compound (II-3)) to the DMF solution containing compound (II-3), stir at 90°C for 0.5h, slowly dropwise add the DMF solution containing R2NHCOCH2Cl, add a small amount of KI after the dropwise addition, continue stirring and react at 100-110°C for 5 hours, cool, pour the reaction mixture into distilled water, stir at room temperature for 5h, filter, wash with water, dry, recrystallize with a (1:1) mixed solvent of ethyl acetate and ethanol to obtain the desired ligand, and store in a vacuum dryer for later use.

[0085] in,

[0086] Ligand A (in formula (II), R1 is methyl and R2 is phenyl), whose molecular formula is C 17 H 15 N3O3 (measured): 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), whose molecular formula is C 17H 14 ClN3O3 (found): 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 methylnaphthyl), whose molecular formula is C 27 H 21 N3O3 (measured): 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 metal zinc complex A (in formula (I), R1 is methyl, R2 is phenyl, and R3 is methyl)

[0091] Ligand A has a structure as shown in formula (II), wherein R1 is methyl and R2 is phenyl. Weigh 1.0 mmol of ligand A, add ethanol, adjust the pH value to 8 with dilute NaOH to completely dissolve the ligand, add an ethanol solution containing an equal amount of Zn(CH3COO)2·2H2O, and a white precipitate appears. Stir at room temperature for 5 hours, centrifuge, wash with anhydrous ethanol 2-3 times, and vacuum dry to obtain a metal zinc complex A with a yield of 43%.

[0092] The elemental analysis data of the product are: C 19 H 18 N3O5Zn (measured): 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 metal zinc complex B (in formula (I), R1 is chlorine, R2 is benzyl, and R3 is methyl)

[0095] Ligand B has a structure as shown in formula (II), wherein R1 is chlorine and R2 is benzyl. Weigh 1.0 mmol of ligand A, add ethanol, adjust the pH value to 8 with dilute NaOH to completely dissolve the ligand, add an ethanol solution containing an equal amount of Zn(CH3COO)2·2H2O, and a white precipitate appears. Stir at room temperature for 5 hours, centrifuge, wash with anhydrous ethanol 2-3 times, and vacuum dry to obtain a metal zinc complex A with a yield of 41%.

[0096] The elemental analysis data of the product are: C 19 H 17N3O5Zn (measured): 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 metal zinc complex C (in formula (I), R1 is phenyl, R2 is methylnaphthyl, and R3 is methyl)

[0099] Ligand C has a structure as shown in formula (II), wherein R1 is phenyl and R2 is methylnaphthyl. Weigh 1.0 mmol of ligand A, add ethanol, adjust the pH value to 8 with dilute NaOH to completely dissolve the ligand, add an ethanol solution containing an equal amount of Zn(CH3COO)2·2H2O, and a white precipitate appears. Stir at room temperature for 5 hours, centrifuge, wash with anhydrous ethanol 2-3 times, and vacuum dry to obtain a metal zinc complex A with a yield of 41%.

[0100] The elemental analysis data of the product are: C 29 H 24 N3O5Zn (measured): 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 metal zinc complex D (in formula (I), R1 is phenyl, R2 is methylnaphthyl, and R3 is ethyl)

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

[0104] Example 1

[0105] At room temperature, 10 μmol of metal zinc complex A, 10 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 40 mmol of L-lactide monomer was added. The mixture was stirred and reacted at 70° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0106] The conversion rate was 91% according to NMR test.

[0107] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is M w / M nis 1.26.

[0108] Example 2

[0109] At room temperature, 10 μmol of metal zinc complex A, 10 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 20 mmol of L, D-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation, and a white solid was obtained by filtration. The white solid was dried in a vacuum drying oven at 40° C. for 48 h to obtain a polylactide solid.

[0110] The conversion rate was 91% according to NMR test.

[0111] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is M w / M n is 1.24.

[0112] Example 3

[0113] At room temperature, 10 μmol of metal zinc complex B, 10 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 10 mmol of L-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0114] The conversion rate was 95% as determined by NMR.

[0115] The number average molecular weight M of polylactide was measured by GPC analysis. n 108,000, and the molecular weight distribution is M w / M n is 1.18.

[0116] Example 4

[0117] At room temperature, 10 μmol of metal zinc complex C, 100 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 10 mmol of L, D-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0118] The conversion rate was 95% as determined by NMR.

[0119] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is M w / M n is 1.20.

[0120] Example 5

[0121] At room temperature, 10 μmol of metal zinc complex B, 10 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 5 mmol of L-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0122] The conversion rate was 92% according to the NMR test.

[0123] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is M w / M n is 1.23.

[0124] Example 6

[0125] At room temperature, 10 μmol of metal zinc complex C, 200 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 10 mmol of L-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0126] The conversion rate was 94% according to NMR test.

[0127] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is M w / M n is 1.14.

[0128] Example 7

[0129] At room temperature, 10 μmol of metal zinc complex A, 500 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 10 mmol of L, D-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0130] The conversion rate was 95% as determined by NMR.

[0131] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is M w / M n is 1.13.

[0132] Example 8

[0133] At room temperature, 10 μmol of metal zinc complex C, 10 μmol of benzyl alcohol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 1 mmol of L-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0134] The conversion rate was 90% as tested by NMR.

[0135] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is 14,200. w / M n is 1.25.

[0136] Example 9

[0137] At room temperature, 10 μmol of metal zinc complex A, 10 μmol of isopropanol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 10 mmol of L-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0138] The conversion rate was 95% as determined by NMR.

[0139] The number average molecular weight M of polylactide was measured by GPC analysis. n 101,000, and the molecular weight distribution is Mw / M n is 1.20.

[0140] Example 10

[0141] At room temperature, 10 μmol of metal zinc complex B, 0.5 μmol of benzyl alcohol, 0.5 μmol of benzhydrol and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 5 mmol of L, D-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0142] The conversion rate was 91% according to NMR test.

[0143] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is M w / M n is 1.23.

[0144] Embodiment 11

[0145] The method of Example 1 was followed, except that the metal zinc complex A was replaced by the metal zinc complex D, and a polylactide solid was obtained in the same manner.

[0146] The conversion rate was 89% according to NMR test.

[0147] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is M w / M n is 1.25.

[0148] Comparative Example 1

[0149] At room temperature, 10 μmol of metal zinc complex A and 10 mL of toluene solvent were added to a 20 mL polymerization bottle treated with anhydrous and oxygen-free conditions, and 1 mmol of L-lactide monomer was added. The mixture was stirred and reacted at 100° C. for 48 h. Then, a 10 v% ethanol solution of hydrochloric acid was added to terminate the reaction. The reaction solution was poured into ethanol for precipitation 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 a polylactide solid.

[0150] The conversion rate was 69% according to NMR test.

[0151] The number average molecular weight M of polylactide was measured by GPC analysis. n The molecular weight distribution is M w / M nis 1.25.

[0152] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A catalyst composition, characterized in that The catalyst composition comprises a metal zinc complex represented by formula (I) and a hydroxyl-containing compound. In formula (I), R1 is a C1-C6 alkyl, a halogen, or a hydrogen atom on an aryl group substituted by at least one group selected from halogen, a C1-C6 alkyl, or an unsubstituted C6-C 12 R2 is a C1-C6 alkyl, a halogen, or a hydrogen atom on the aryl group is substituted by at least one group selected from halogen, C1-C6 alkyl or an unsubstituted C6-C 12 R3 is a C1-C6 alkyl group.

2. The catalyst composition according to claim 1, wherein The C1-C6 alkyl group is methyl, ethyl or propyl; Preferably, the halogen is fluorine, chlorine, bromine or iodine, more preferably chlorine or bromine; Preferably, R1 is methyl, ethyl, propyl, chlorine, bromine, phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl or propylphenyl, more preferably methyl, chlorine, bromine, phenyl, chlorophenyl or methylphenyl; Preferably, R2 is phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl, propylphenyl, naphthyl or naphthyl, more preferably phenyl, chlorophenyl, methylphenyl, naphthyl or naphthyl; Preferably, R3 is methyl.

3. The catalyst composition according to claim 1, wherein The hydroxyl-containing compound is an alcohol compound and / or a phenol compound; Preferably, the hydroxyl-containing compound is a substituted or unsubstituted C1-C5 straight-chain or branched fatty alcohol, a C6-C 20 At least one of an aromatic alcohol, a C4-C6 alcohol amine and a phenol, wherein the substituted group is selected from a C1-C6 alkyl, a C1-C6 alkoxy or a C6-C 10 Aryl; Preferably, the hydroxyl-containing compound is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, triethanolamine, benzhydrol, triphenylmethanol, benzyl alcohol and phenol.

4. The catalyst composition according to any one of claims 1 to 3, wherein The molar ratio of the metal zinc complex to the hydroxyl-containing compound is 1:0.01-1000, preferably 1:0.1-700, and more preferably 1:0.5-500.

5. A method for preparing polylactide, characterized in that: The preparation method comprises the steps of: subjecting a lactide monomer to solution polymerization in the presence of a metal zinc complex represented by formula (I) and a hydroxyl-containing compound; In formula (I), R1 is a C1-C6 alkyl, a halogen, or a hydrogen atom on an aryl group substituted by at least one group selected from halogen, a C1-C6 alkyl, or an unsubstituted C6-C 12 R2 is a C1-C6 alkyl, a halogen, or a hydrogen atom on the aryl group is substituted by at least one group selected from halogen, C1-C6 alkyl or an unsubstituted C6-C 12 R3 is a C1-C6 alkyl group.

6. The method according to claim 5, wherein: The C1-C6 alkyl group is methyl, ethyl or propyl; Preferably, the halogen is fluorine, chlorine, bromine or iodine, more preferably chlorine or bromine; Preferably, R1 is methyl, ethyl, propyl, chlorine, bromine, phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl or propylphenyl, more preferably methyl, chlorine, bromine, phenyl, chlorophenyl or methylphenyl; Preferably, R2 is phenyl, chlorophenyl, bromophenyl, methylphenyl, ethylphenyl, propylphenyl, naphthyl or naphthyl, more preferably phenyl, chlorophenyl, methylphenyl, naphthyl or naphthyl; Preferably, R3 is methyl.

7. The method according to claim 5, wherein: The hydroxyl-containing compound is an alcohol compound and / or a phenol compound; Preferably, the hydroxyl-containing compound is a substituted or unsubstituted C1-C5 straight-chain or branched fatty alcohol, a C6-C 20 At least one of an aromatic alcohol, a C4-C6 alcohol amine and a phenol, wherein the substituted group is selected from a C1-C6 alkyl, a C1-C6 alkoxy or a C6-C 10 Aryl; Preferably, the hydroxyl-containing compound is at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, triethanolamine, benzhydrol, triphenylmethanol, benzyl alcohol and phenol.

8. The method according to any one of claims 5 to 7, wherein: The conditions of the solution polymerization include: reaction temperature of 10-160° C., preferably 25-100° C.; reaction time of 0.02-56 h, preferably 3-52 h.

9. The method according to any one of claims 5 to 7, wherein: The molar ratio of the metal zinc complex to the hydroxyl-containing compound is 1:0.01-1000, preferably 1:0.1-700, more preferably 1:0.5-500; Preferably, the molar ratio of the hydroxyl-containing compound to the lactide monomer is 1:1-20000, preferably 1:20-19000, more preferably 1:50-18000, more preferably 1:100-16000, more preferably 1:200-15000, further preferably 500-5000; Preferably, the molar ratio of the metal zinc complex represented by formula (I) to the lactide monomer is 1:1-10000, preferably 1:50-5000, and more preferably 1:100-2000.

10. The polylactide prepared by the method for preparing polylactide according to any one of claims 5 to 9.

11. Use of the catalyst composition according to any one of claims 1 to 4 in the preparation of polylactide.

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