Heteronuclear bimetallic catalyst as well as preparation method and application thereof

Abstract

The invention relates to a heteronuclear bimetallic catalyst as well as a preparation method and application thereof. The heteronuclear bimetallic catalyst is applied to preparation of a terpolymer. The heteronuclear bimetallic catalyst takes Schiff base terminated polyether polyol as a flexible ligand, the distance between metal and metal and the distance between metal and a ligand skeleton can be regulated and controlled, different intracavity structures are converted according to different reaction monomers, the prepared terpolymer has various and controllable structures, the application range of the terpolymer is widened, and the heteronuclear bimetallic catalyst has wide application prospects. Meanwhile, the method has a prospect of realizing industrial production.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and in particular relates to a heteronuclear bimetallic catalyst, its preparation method and application. Background Technology

[0002] Bio-based polyesters or polycarbonates, with their excellent renewability, biocompatibility, and biodegradability, are increasingly becoming alternatives to petrochemical-based polymers. These materials not only address the unsustainable use of petrochemical energy but also offer superior thermodynamic properties due to their structural characteristics. Among various synthetic routes, ring-opening copolymerization of epoxides and cyclic anhydrides can prepare polyesters with diverse structures, while copolymerization of epoxides and carbon dioxide can prepare polycarbonates. Both methods feature high atom utilization, high polymer alternation, and controllable molecular weight. Ternary copolymerization of epoxides, cyclic anhydrides, and carbon dioxide produces polymers that combine the advantages of both polyesters and polycarbonates, while offering greater structural flexibility and easily controllable and adjustable properties. However, the primary reason for the limited application of these polymers is the lack of high-performance, versatile, and mass-producible catalytic systems. Among numerous catalytic systems, metal-containing complexes currently exhibit the highest catalytic activity. The core of this approach is to coordinate a metal in a suitable ligand cavity, thereby recognizing and activating the monomer through the coordination of the metal. The most representative example is the catalytic system with a Schiff base structure, which can achieve good conversion of epoxides, cyclic anhydrides and carbon dioxide under mild conditions.

[0003] This invention fully investigates the catalytic mechanism of catalytic systems based on Schiff base structures and designs and synthesizes a heteronuclear bimetallic catalyst. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a heteronuclear bimetallic catalyst, its preparation method, and its applications.

[0005] Therefore, in a first aspect, the present invention provides a heteronuclear bimetallic catalyst having the structure of the following formula (1):

[0006]

[0007] Where m≥1 and is an integer; n≥1 and is an integer; M and M1 may be the same or different, and each is independently selected from a metallic element; X and Y may be the same or different, and each is independently selected from a Lewis acid anion; R1 and R2 may be the same or different, and each is independently selected from any one of H, C1-C6 alkyl, C1-C6 alkoxy, halogen, and NO2 groups.

[0008] In some embodiments of the present invention, M is selected from any one of Co, Al, Cr, and Zn.

[0009] In some embodiments of the present invention, M1 is selected from any one of Li, Na, and K.

[0010] In some embodiments of the present invention, X is selected from C1 -1 NO3 -1 ClO4 -1 BPh4 -1 CF3COO -1 CH3COO -1 BF4 -1 N3 -1 Any one of them.

[0011] In some embodiments of the present invention, Y is selected from Cl. -1 NO3 -1 ClO4 -1 BPh4 -1 CF3COO -1 CH3COO -1 BF4 -1 N3 -1 Any one of them.

[0012] In some embodiments of the present invention, m = 1, 2, 3.

[0013] In some embodiments of the present invention, n = 1, 2, 3.

[0014] In some embodiments of the present invention, the halogen includes any one of F, Cl, and Br.

[0015] This heteronuclear bimetallic catalyst uses Schiff base-terminated polyether polyols as ligands, combined with heteronuclear bimetals with adjustable spacing. Through bimetallic synergistic catalysis, the ternary copolymerization activity of epoxides, cyclic anhydrides, and carbon dioxide is greatly enhanced. Simultaneously, the Schiff base-terminated polyether polyol backbone possesses a degree of flexibility, allowing for control of the distances between metals and between metals and ligands. Different intracavitary structures are achieved for different monomer transformations, enabling the ternary copolymerization of various epoxides, cyclic anhydrides, and carbon dioxide within the same catalytic system. Furthermore, the catalyst structure is more stable, and the ligand-metal bond is tighter, allowing for stable storage in air.

[0016] The second aspect of the present invention provides a method for preparing a heteronuclear bimetallic catalyst, comprising reacting a disubstituted salicylaldehyde and a polyol diamine dissolved in an organic solvent 1 under normal pressure under an inert gas protection to obtain a heteronuclear bimetallic ligand, reacting the heteronuclear bimetallic ligand with MY dissolved in an organic solvent 3, and then adding M1X to react and obtain a heteronuclear bimetallic catalyst.

[0017] In some embodiments of the present invention, after the disubstituted salicylaldehyde and polyol diamine react, the organic solvent 1 is removed under reduced pressure to obtain crude heteronuclear bimetallic ligands. The crude heteronuclear bimetallic ligands are then added to organic solvent 2 and pulped for 3-5 hours, filtered, and dried to obtain heteronuclear bimetallic ligands.

[0018] In some embodiments of the present invention, after the reaction with M1X, the organic solvent 1 is removed under reduced pressure and the product is dried under vacuum to obtain a heteronuclear bimetallic catalyst.

[0019] In some embodiments of the present invention, the disubstituted salicylaldehyde includes any one of 5-methylsalicylaldehyde, 3-ethyl-5-ethylsalicylaldehyde, 3-methoxy-5-tert-butylsalicylaldehyde, 3-methoxy-5-nitrosalicylaldehyde, 3-tert-butoxy-5-fluorosalicylaldehyde, and 3-ethoxy-5-ethoxysalicylaldehyde.

[0020] In some embodiments of the present invention, the molar ratio of the disubstituted salicylaldehyde to the polyol diamine is 1.6-4.0:1.

[0021] In some embodiments of the present invention, the molar ratio of the heteronuclear bimetallic ligand to MY is 0.8-2.0:1.

[0022] In some embodiments of the present invention, the molar ratio of the heteronuclear bimetallic ligand to M1X is 0.8-2.0:1.

[0023] In some embodiments of the present invention, the organic solvent 1 includes any one of dichloromethane, dichloroethane, 1,4-dioxane, and tetrahydrofuran.

[0024] In some embodiments of the present invention, the organic solvent 2 includes any one of methanol, ethanol, isopropanol, and n-butanol.

[0025] In some embodiments of the present invention, the organic solvent 3 includes any one of dichloromethane, dichloroethane, 1,4-dioxane, and tetrahydrofuran.

[0026] In some embodiments of the present invention, the reaction temperature of the disubstituted salicylaldehyde with the polyol diamine is 20-50°C, and the reaction time is 6-8 hours.

[0027] In some embodiments of the present invention, the reaction temperature of the heteronuclear bimetallic ligand with MY is 30-50°C, and the reaction time is 20-24h.

[0028] In some embodiments of the present invention, the reaction temperature after adding M1X is 90-120°C and the reaction time is 13-15h.

[0029] In some embodiments of the present invention, M is selected from any one of Co, Al, Cr, and Zn.

[0030] In some embodiments of the present invention, M1 is selected from any one of Li, Na, and K;

[0031] In some embodiments of the present invention, X is selected from C1 -1 NO3 -1 ClO4 -1 BPh4 -1 CF3COO -1 CH3COO -1 BF4 -1 N3 -1 Any one of them;

[0032] In some embodiments of the present invention, Y is selected from Cl. -1 NO3 -1 ClO4 -1 BPh4 -1 CF3COO -1 CH3COO -1 BF4 -1 N3 -1 Any one of them.

[0033] In some embodiments of the present invention, the polyol diamine has the structure of formula (2):

[0034]

[0035] Where m≥1 and is an integer; n≥1 and is an integer.

[0036] In some embodiments of the present invention, m = 1, 2, 3.

[0037] In some embodiments of the present invention, n = 1, 2, 3.

[0038] In some embodiments of the present invention, the heteronuclear bimetallic ligand has the structure of formula (3) as follows:

[0039]

[0040] Where m ≥ 1 and is an integer; n ≥ 1 and is an integer; R1 and R2 may be the same or different, and each is independently selected from any one of H, C1-C6 alkyl, C1-C6 alkoxy, halogen, and NO2 groups.

[0041] In some embodiments of the present invention, m = 1, 2, 3.

[0042] In some embodiments of the present invention, n = 1, 2, 3.

[0043] In some embodiments of the present invention, the halogen includes any one of F, Cl, and Br.

[0044] In some embodiments of the present invention, the synthesis reaction equation for the heteronuclear bimetallic catalyst is as follows:

[0045]

[0046] A third aspect of the present invention provides a catalyst prepared by the method described in the second aspect of the present invention.

[0047] The fourth aspect of the present invention provides the use of the catalyst as described in the first aspect of the present invention or the catalyst as described in the third aspect of the present invention in the preparation of terpolymers using epoxides, cyclic anhydrides and carbon dioxide.

[0048] The fifth aspect of the present invention provides a method for preparing a ternary copolymer, comprising mixing a heteronuclear bimetallic catalyst, an epoxide alkane and a cyclic anhydride, introducing carbon dioxide, selectively adding an organic solvent 4 and reacting at 0.3-3 MPa to obtain a crude product; washing the crude product to precipitate and obtaining the ternary copolymer.

[0049] In some embodiments of the present invention, the crude product is dissolved in dichloromethane, then methanol is added, and the mixture is stirred vigorously to precipitate the polymer.

[0050] In some embodiments of the present invention, the crude product washing and precipitation is repeated 3-5 times.

[0051] In some embodiments of the present invention, the molar ratio of the heteronuclear bimetallic catalyst to the epoxide is 1:500-25000.

[0052] In some embodiments of the present invention, the molar ratio of the epoxide to the cyclic anhydride is 0.8-2.0:1.

[0053] In some embodiments of the present invention, the organic solvent 4 includes any one of 1,4-dioxane, toluene, n-hexane, cyclohexane, and dichloroethane.

[0054] In some embodiments of the present invention, the reaction includes the following conditions: the reaction temperature is 35-150°C, preferably 100-130°C; and / or the reaction time is 1-15 h; and / or the carbon dioxide pressure is 0.3-3 MPa.

[0055] In some embodiments of the present invention, the synthesis reaction equation of the ternary copolymer is as follows:

[0056]

[0057] Where x and y are any integers between 1 and 1000.

[0058] In some embodiments of the present invention, the cyclic anhydride is selected from any one of the following cyclic anhydrides:

[0059]

[0060] In some embodiments of the present invention, the epoxide is selected from any one of the following epoxides:

[0061]

[0062] In some embodiments of the present invention, the number-average molecular weight of the terpolymer is ≥3.0 kg / mol.

[0063] In some embodiments of the present invention, the number-average molecular weight of the terpolymer is 3.0-100.0 kg / mol.

[0064] In some embodiments of the present invention, the molecular weight distribution of the terpolymer is ≤1.5.

[0065] In some embodiments of the present invention, the molecular weight distribution of the terpolymer is 1.1-1.5.

[0066] Beneficial effects:

[0067] 1. The heteronuclear bimetallic catalyst provided by the present invention uses Schiff base-terminated polyether polyol as a flexible ligand, and the types of heteronuclear bimetals that can be matched are adjustable, the distance between the bimetals is adjustable, the distance between the metal and the ligand skeleton is adjustable, and it can be adapted to a variety of monomer structures, and can prepare a wide variety of terpolymers.

[0068] 2. The heteronuclear bimetallic catalyst provided by this invention can achieve bimetallic synergistic catalysis, and has higher activity than traditional single metal catalysts, greatly reducing the proportion of catalyst used.

[0069] 3. The heteronuclear bimetallic catalyst provided by this invention has a stable structure, the ligands are tightly bound to the metal, and it can be stably stored in air.

[0070] 4. The heteronuclear bimetallic catalyst provided by this invention has a short preparation route and mild reaction conditions, and has the prospect of industrial production.

[0071] 5. The ternary polymer prepared using the heteronuclear bimetallic catalyst provided by this invention has a number-average molecular weight of up to 95.1 kg / mol, a molecular weight distribution of 1.1-1.5, diverse structural properties that can be regulated, and combines the advantages of polyester and polycarbonate, making it widely applicable. Detailed Implementation

[0072] To make the present invention easier to understand, the present invention will be described in detail below with reference to embodiments. These embodiments are for illustrative purposes only and are not limited to the scope of application of the present invention.

[0073] The reagents and materials used in this invention are shown in Table 1:

[0074] Table 1 Reagents and Materials

[0075] Raw material name Purity / Specifications source 5-Methylsalicylaldehyde Analytical Pure Commercially available polyol diamine Analytical Pure Commercially available <![CDATA[CrCl3]]> Analytical Pure Commercially available <![CDATA[CH3COONa]]> Analytical Pure Commercially available 3-Ethyl-5-ethylsalicylic acid Analytical Pure Commercially available <![CDATA[Co(CF3COO)2]]> Analytical Pure Commercially available LiCl Analytical Pure Commercially available 3-Methoxy-5-nitrosalicylaldehyde Analytical Pure Commercially available <![CDATA[Co(CH3COO)2]]> Analytical Pure Commercially available KCl Analytical Pure Commercially available 3-tert-butoxy-5-fluorosalicylaldehyde Analytical Pure Commercially available <![CDATA[AlCl3]]> Analytical Pure Commercially available <![CDATA[NaBF4]]> Analytical Pure Commercially available 3-Ethoxy-5-ethoxysalicylaldehyde Analytical Pure Commercially available <![CDATA[Zn(CH3COO)2]]> Analytical Pure Commercially available <![CDATA[KClO4]]> Analytical Pure Commercially available

[0076] The structures of the cyclic anhydrides, epoxy alkanes, and heteronuclear bimetallic catalysts used in the examples are shown below:

[0077]

[0078] 1c: m=1, n=1, R1=H, R2=Me, M=Cr, M1=Na, X=CH3COO -1 Y = Cl -1 ,

[0079] 2c: m=1, n=2, R1=Et, R2=Et, M=Cr, M1=K, X=ClO4 -1 Y = Cl -1 ,

[0080] 3c: m=2, n=2, R1=OMe, R2= t Bu, M=Co, M1=Li, X=Cl -1 Y = CF3COO -1 ,

[0081] 4c: m=3, n=3, R1=OMe, R2=NO2, M=Co, M1=K, X=Cl -1 Y = CH3COO -1 ,

[0082] 5c: m=3, n=3, R1=0 t Bu, R2=F, M=Al, M1=Na, X=BF4 -1 Y = Cl -1 ,

[0083] 6c: m=3, n=3, R1=OEt, R2=OEt, M=Zn, M1=K, X=ClO4 -1 Y = CH3COO -1 .

[0084] Example 1

[0085] This embodiment provides a method for preparing a heteronuclear bimetallic catalyst, comprising: mixing 10.9 g of 5-methylsalicylaldehyde (80.0 mmol) and 10.4 g of polyol diamine (50.0 mmol; n=1, m=1) under inert gas protection, adding dichloromethane and stirring to dissolve, continuing the reaction at 25°C for 6 h, cooling to room temperature, removing dichloromethane under reduced pressure to obtain crude heteronuclear bimetallic ligand (n=1, m=1), adding methanol and stirring for 3 h, filtering, ... The heteronuclear bimetallic ligand was obtained by drying. 3.5 g of the heteronuclear bimetallic ligand (8.0 mmol) and 1.2 g of CrCl3 (10.0 mmol) were mixed under inert gas protection, dissolved in 1,4-dioxane, and stirred at 30 °C for 24 h. Then 1.4 g of CH3COONa (10.0 mmol) was added, and the reaction was stopped by stirring at 90 °C for 15 h. The 1,4-dioxane was removed under reduced pressure, and the heteronuclear bimetallic catalyst 1c was obtained after vacuum drying.

[0086] Example 2

[0087] This embodiment provides a method for preparing a heteronuclear bimetallic catalyst, comprising: mixing 17.8 g of 3-ethyl-5-ethylsalicylaldehyde (100.0 mmol) and 12.6 g of polyol diamine (50.0 mmol; n=2, m=1) under inert gas protection, adding dichloromethane and stirring to dissolve, continuing the reaction at 30°C for 6 h, cooling to room temperature, removing dichloromethane under reduced pressure to obtain crude heteronuclear bimetallic ligand (n=2, m=1), and adding methanol and stirring for 3 h. The heteronuclear bimetallic ligand was obtained by filtration and drying. 5.7 g of heteronuclear bimetallic ligand (10.0 mmol) and 1.2 g of CrCl3 (10.0 mmol) were mixed under inert gas protection, dissolved in 1,4-dioxane, and stirred at 30 °C for 24 h. Then 1.4 g of KClO4 (10.0 mmol) was added, and the reaction was stopped by stirring at 90 °C for 13 h. The 1,4-dioxane was removed under reduced pressure, and the heteronuclear bimetallic catalyst 2c was obtained after vacuum drying.

[0088] Example 3

[0089] This embodiment provides a method for preparing a heteronuclear bimetallic catalyst, comprising: mixing 31.2 g of 3-methoxy-5-tert-butylsalicylaldehyde (150.0 mmol) and 14.0 g of polyol diamine (50.0 mmol; n=2, m=2) under an inert gas protection, adding dichloroethane and stirring to dissolve, continuing the reaction at 35°C for 8 h, cooling to room temperature, removing dichloroethane under reduced pressure to obtain a crude heteronuclear bimetallic ligand (n=2, m=2), and adding ethanol. The mixture was pulped for 4 hours, filtered, and dried to obtain a heteronuclear bimetallic ligand. Under inert gas protection, 9.9 g of the heteronuclear bimetallic ligand (15.0 mmol) and 2.3 g of Co(CF3COO)2 (10.0 mmol) were mixed, dissolved in toluene, and stirred at 35 °C for 20 hours. Then, 0.4 g of LiCl (10.0 mmol) was added, and the mixture was stirred at 100 °C for 15 hours. The reaction was then stopped, toluene was removed under reduced pressure, and the mixture was dried under vacuum to obtain the heteronuclear bimetallic catalyst 3c.

[0090] Example 4

[0091] This embodiment provides a method for preparing a heteronuclear bimetallic catalyst, comprising: mixing 39.4 g of 3-methoxy-5-nitrosalicylic aldehyde (200.0 mmol) and 17.6 g of polyol diamine (50.0 mmol; n=3, m=3) under an inert gas protection, adding tetrahydrofuran and stirring to dissolve, continuing the reaction at 50°C for 6 h, cooling to room temperature, removing tetrahydrofuran under reduced pressure to obtain a crude heteronuclear bimetallic ligand (n=3, m=3), and then adding isopropanol to slurry. After 5 hours, the mixture was filtered and dried to obtain the heteronuclear bimetallic ligand. Under inert gas protection, 14.2 g of the heteronuclear bimetallic ligand (20.0 mmol) and 1.8 g of Co(CH3COO)2 (10.0 mmol) were mixed, dissolved in dichloroethane, and stirred at 50 °C for 20 hours. Then, 0.7 g of KCl (10.0 mmol) was added, and the mixture was stirred at 120 °C for 15 hours. The reaction was then stopped, and the dichloroethane was removed under reduced pressure. After vacuum drying, the heteronuclear bimetallic catalyst 4c was obtained.

[0092] Example 5

[0093] This embodiment provides a method for preparing a heteronuclear bimetallic catalyst, comprising: mixing 21.2 g of 3-tert-butoxy-5-fluorosalicylaldehyde (100.0 mmol) and 17.6 g of polyol diamine (50.0 mmol; n=3, m=3) under an inert gas protection, adding dichloroethane and stirring to dissolve, continuing the reaction at 50°C for 8 h, cooling to room temperature, removing dichloroethane under reduced pressure to obtain a crude heteronuclear bimetallic ligand (n=3, m=3), and adding n-butanol. The mixture was pulped for 4 hours, filtered, and dried to obtain heteronuclear bimetallic ligands. Under inert gas protection, 11.1 g of heteronuclear bimetallic ligands (15.0 mmol) and 1.3 g of AlCl3 (10.0 mmol) were mixed, dissolved in dichloroethane, and stirred at 50 °C for 24 hours. Then, 1.1 g of NaBF4 (10.0 mmol) was added, and the mixture was stirred at 120 °C for 15 hours. The reaction was then stopped, and the dichloroethane was removed under reduced pressure. After vacuum drying, heteronuclear bimetallic catalyst 5c was obtained.

[0094] Example 6

[0095] This embodiment provides a method for preparing a heteronuclear bimetallic catalyst, comprising: mixing 25.2 g of 3-ethoxy-5-ethoxysalicylaldehyde (120.0 mmol) and 17.6 g of polyol diamine (50.0 mmol; n = 3, m = 3) under an inert gas protection, adding 1,4-dioxane and stirring to dissolve, continuing the reaction at 50 °C for 8 h, cooling to room temperature, and removing 1,4-dioxane under reduced pressure to obtain a crude heteronuclear bimetallic ligand (n = 3, m = 3). Methanol was added and stirred for 5 hours, then filtered and dried to obtain heteronuclear bimetallic ligands. 7.4 g of heteronuclear bimetallic ligands (10.0 mmol) and 1.8 g of Zn(CH3COO)2 (10.0 mmol) were mixed under inert gas protection, dissolved in toluene, and stirred at 50 °C for 24 hours. Then, 1.4 g of KClO4 (10.0 mmol) was added, and the mixture was stirred at 120 °C for 15 hours. The reaction was then stopped, toluene was removed under reduced pressure, and the mixture was dried under vacuum to obtain heteronuclear bimetallic catalyst 6c.

[0096] Example 7

[0097] This embodiment provides a method for preparing a terpolymer, comprising: drying a 100mL high-pressure reactor equipped with a magnetic inlet at 120℃ for more than 12 hours, evacuating it and cooling it to room temperature, and purging it with nitrogen gas for use; under nitrogen protection, weighing a certain amount of heteronuclear bimetallic catalyst 1c at room temperature, wherein the molar ratio of heteronuclear bimetallic catalyst 1c to epoxide alkane 1b is 1:500, the molar ratio of epoxide alkane 1b to cyclic anhydride 1a is 1:1, the carbon dioxide gas pressure is 0.3MPa, adding toluene, reacting at 35℃ for 1 hour, stopping stirring, releasing unreacted carbon dioxide gas, drying the toluene under reduced pressure, and taking out a very small amount of the reaction mixture for GPC testing; dissolving the remaining crude polymer in a small amount of dichloromethane, then adding a large amount of methanol, and stirring vigorously to precipitate the polymer, repeating this precipitation process repeatedly, and drying under vacuum to obtain terpolymer 1.

[0098] GPC testing showed a number-average molecular weight of 3.3 kg / mol and a molecular weight distribution of 1.1.

[0099] Example 8

[0100] This embodiment provides a method for preparing a terpolymer, comprising: drying a 100mL high-pressure reactor equipped with a magnetic inlet at 120℃ for more than 12 hours, evacuating it and cooling it to room temperature, and purging it with nitrogen gas for use; under nitrogen protection, weighing a certain amount of heteronuclear bimetallic catalyst 2c at room temperature, wherein the molar ratio of heteronuclear bimetallic catalyst 2c to epoxide alkane 2b is 1:1000, the molar ratio of epoxide alkane 2b to cyclic anhydride 2a is 1:1, the carbon dioxide gas pressure is 1MPa, adding n-hexane, reacting at 50℃ for 3 hours, stopping stirring, releasing unreacted carbon dioxide gas, evacuating n-hexane under reduced pressure, and taking out a very small amount of the reaction mixture for GPC testing; dissolving the remaining crude polymer in a small amount of dichloromethane, then adding a large amount of methanol, and stirring vigorously to precipitate the polymer, repeating this precipitation process repeatedly, and drying under vacuum to obtain terpolymer 2.

[0101] GPC testing showed that the copolymer had a number-average molecular weight of 23.6 kg / mol and a molecular weight distribution of 1.2.

[0102] Example 9

[0103] This embodiment provides a method for preparing a terpolymer, comprising: drying a 100mL high-pressure reactor equipped with a magnetic inlet at 120℃ for more than 12 hours, evacuating it and cooling it to room temperature, and purging it with nitrogen gas for use; under nitrogen protection, weighing a certain amount of heteronuclear bimetallic catalyst 3c at room temperature, wherein the molar ratio of heteronuclear bimetallic catalyst 3c to epoxide alkane 3b is 1:25000, the molar ratio of epoxide alkane 3b to cyclic anhydride 3a is 1:1, the carbon dioxide gas pressure is 1.5MPa, adding 1,4-dioxane, reacting at 100℃ for 15 hours, stopping stirring, releasing unreacted carbon dioxide gas, evacuating 1,4-dioxane under reduced pressure, and taking out a very small amount of the reaction mixture for GPC testing; dissolving the remaining crude polymer in a small amount of dichloromethane, then adding a large amount of methanol, and stirring vigorously to precipitate the polymer, repeating this precipitation process repeatedly, and drying under vacuum to obtain terpolymer 3.

[0104] GPC testing showed that the copolymer had a number-average molecular weight of 45.9 kg / mol and a molecular weight distribution of 1.3.

[0105] Example 10

[0106] This embodiment provides a method for preparing a terpolymer, comprising: drying a 100mL high-pressure reactor equipped with a magnetic inlet at 120℃ for more than 12 hours, evacuating it and cooling it to room temperature, and purging it with nitrogen gas for use; under nitrogen protection, weighing a certain amount of heteronuclear bimetallic catalyst 4c at room temperature, wherein the molar ratio of heteronuclear bimetallic catalyst 4c to epoxide 4b is 1:15000, the molar ratio of epoxide 4b to cyclic anhydride 4a is 1:1, the carbon dioxide gas pressure is 2MPa, adding dichloroethane, reacting at 120℃ for 10 hours, stopping stirring, releasing unreacted carbon dioxide gas, evacuating dichloroethane under reduced pressure, and taking out a very small amount of the reaction mixture for GPC testing; dissolving the remaining crude polymer in a small amount of dichloromethane, then adding a large amount of methanol, and stirring vigorously to precipitate the polymer, repeating this precipitation process repeatedly, and drying under vacuum to obtain terpolymer 4.

[0107] GPC testing showed that the copolymer had a number-average molecular weight of 95.1 kg / mol and a molecular weight distribution of 1.4.

[0108] Example 11

[0109] This embodiment provides a method for preparing a terpolymer, comprising: drying a 100mL high-pressure reactor equipped with a magnetic inlet at 120℃ for more than 12 hours, evacuating it and cooling it to room temperature, and purging it with nitrogen gas for use; under nitrogen protection, weighing a certain amount of heteronuclear bimetallic catalyst 5c at room temperature, wherein the molar ratio of heteronuclear bimetallic catalyst 5c to epoxide 5b is 1:10000, the molar ratio of epoxide 5b to cyclic anhydride 5a is 1:1, the carbon dioxide gas pressure is 2.5MPa, adding toluene, reacting at 150℃ for 8 hours, stopping stirring, releasing unreacted carbon dioxide gas, drying the toluene under reduced pressure, and taking out a very small amount of the reaction mixture for GPC testing; dissolving the remaining crude polymer in a small amount of dichloromethane, then adding a large amount of methanol, and stirring vigorously to precipitate the polymer, repeating this precipitation process repeatedly, and drying under vacuum to obtain terpolymer 5.

[0110] GPC testing showed that the copolymer had a number-average molecular weight of 66.9 kg / mol and a molecular weight distribution of 1.5.

[0111] Example 12

[0112] This embodiment provides a method for preparing a terpolymer, comprising: drying a 100mL high-pressure reactor equipped with a magnetic inlet at 120℃ for more than 12 hours, evacuating it and cooling it to room temperature, and purging it with nitrogen gas for use; under nitrogen protection, weighing a certain amount of heteronuclear bimetallic catalyst 6c at room temperature, wherein the molar ratio of heteronuclear bimetallic catalyst 6c to epoxide 6b is 1:5000, the molar ratio of epoxide 6b to cyclic anhydride 6a is 1:1, the carbon dioxide gas pressure is 3MPa, adding toluene, reacting at 150℃ for 12 hours, stopping stirring, releasing unreacted carbon dioxide gas, drying the toluene under reduced pressure, and taking out a very small amount of the reaction mixture for GPC testing; dissolving the remaining crude polymer in a small amount of dichloromethane, then adding a large amount of methanol, and stirring vigorously to precipitate the polymer, repeating this precipitation process repeatedly, and drying under vacuum to obtain terpolymer 6.

[0113] GPC testing showed that the copolymer had a number-average molecular weight of 73.8 kg / mol and a molecular weight distribution of 1.5.

[0114] Comparative Example 1

[0115] This comparative example provides a method for preparing a terpolymer, comprising: drying a 100mL high-pressure reactor equipped with a magnetic inlet at 120℃ for more than 12 hours, evacuating it and cooling it to room temperature, and purging it with nitrogen gas for use; under nitrogen protection, weighing a certain amount of monometallic zinc catalyst at room temperature, wherein the molar ratio of monometallic zinc catalyst to epoxide 1b is 1:50, the molar ratio of epoxide 1b to cyclic anhydride 1a is 1:1, the carbon dioxide gas pressure is 5.1MPa, adding toluene, reacting at 150℃ for 69 hours, stopping stirring, releasing unreacted carbon dioxide gas, drying the toluene under reduced pressure, and taking out a very small amount of the reaction mixture for GPC testing; dissolving the remaining crude polymer in a small amount of dichloromethane, then adding a large amount of methanol, and stirring vigorously to precipitate the polymer, repeating this precipitation process repeatedly, and drying under vacuum to obtain terpolymer 7.

[0116] GPC testing showed that the copolymer had a number-average molecular weight of 28.0 kg / mol and a molecular weight distribution of 3.2.

[0117] As can be seen from the test results of Examples 7-12, the ternary copolymers 1-6 prepared using the heteronuclear bimetallic catalyst provided in this application have a narrow molecular weight distribution, which proves that the active centers of the catalyst are uniform and the molecular structure is controllable; the number average molecular weight can be as high as 95.1 kg / mol, which proves that the prepared ternary copolymers have good mechanical properties.

[0118] The test results of Comparative Example 1 show that the terpolymer 7 prepared using a single-metal catalyst has a wide molecular weight distribution, indicating that the active centers of the catalyst are non-uniform and the molecular structure is uncontrollable. Furthermore, the single-metal catalyst in Comparative Example 1 has a higher feed amount, longer reaction time, and lower catalytic efficiency.

[0119] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A heteronuclear bimetallic catalyst, characterized in that: The catalyst has the structure of the following formula (1): Wherein, m≥1 and is an integer; n≥1 and is an integer; M and M1 are the same or different, and are independently selected from metal elements; X and Y are the same or different, and are independently selected from Lewis acid ions; R1 and R2 are the same or different, and are independently selected from any one of H, C1-C6 alkyl, C1-C6 alkoxy, halogen, and NO2 groups.

2. The catalyst according to claim 1, characterized in that The M is selected from any one of Co, Al, Cr, and Zn; and / or the M1 is selected from any one of Li, Na, and K.

3. The catalyst according to claim 1 or 2, characterized in that The X is selected from Cl -1 、NO3 -1 、ClO4 -1 ,BPh4 -1 CF3COO -1 、CH3COO -1 、BF4 -1 、N3 -1 Any one of; and / or, Y is selected from Cl -1 、NO3 -1 、ClO4 -1 ,BPh4 -1 CF3COO -1 、CH3COO -1 、BF4 -1 、N3 -1 Any one of .

4. A method for preparing a heteronuclear bimetallic catalyst, characterized in that: The method comprises: dissolving disubstituted salicylaldehyde and polyol diamine in an organic solvent 1 for reaction under the protection of an inert gas to obtain a heteronuclear bimetallic ligand; dissolving the heteronuclear bimetallic ligand and MY in an organic solvent 3 for reaction; and then adding M1X for reaction to obtain a heteronuclear bimetallic catalyst; Preferably, the molar ratio of the disubstituted salicylaldehyde to the polyol diamine is 1.6-4.0:1; and / or, the molar ratio of the heteronuclear bimetallic ligand to MY is 0.8-2.0:1; and / or, the molar ratio of the heteronuclear bimetallic ligand to M1X is 0.8-2.0:1; Preferably, the organic solvent 1 includes any one of dichloromethane, dichloroethane, 1,4-dioxane, and tetrahydrofuran; and / or, the organic solvent 3 includes any one of dichloromethane, dichloroethane, 1,4-dioxane, and tetrahydrofuran; Preferably, the reaction temperature of the disubstituted salicylaldehyde and the polyol diamine is 20-50°C, and the reaction time is 6-8h; and / or, the reaction temperature of the heteronuclear bimetallic ligand and MY is 30-50°C, and the reaction time is 20-24h; and / or, the reaction temperature after adding M1X is 90-120°C, and the reaction time is 13-15h.

5. The method according to claim 4, characterized in that The M is selected from any one of Co, Al, Cr, and Zn; and / or the M1 is selected from any one of Li, Na, and K; and / or the X is selected from Cl -1 、NO3 -1 、ClO4 -1 ,BPh4 -1 CF3COO -1 、CH3COO -1 、BF4 -1 、N3 -1 Any one of; and / or, Y is selected from Cl -1 、NO3 -1 、ClO4 -1 ,BPh4 -1 CF3COO -1 、CH3COO -1 、BF4 -1 、N3 -1 Any one of .

6. Use of the catalyst according to any one of claims 1 to 3 or the catalyst prepared by the method according to claim 4 or 5 in the preparation of a terpolymer using alkylene oxide, cyclic anhydride and carbon dioxide.

7. A method for preparing a terpolymer, characterized in that: The method comprises mixing a heteronuclear bimetallic catalyst, an alkylene oxide and a cyclic anhydride, charging carbon dioxide, selectively adding an organic solvent 4 to react at 0.3-3 MPa to obtain a crude product; washing and precipitating the crude product to obtain a terpolymer; Preferably, the molar ratio of the heteronuclear bimetallic catalyst to the alkylene oxide is 1:500-25000; and / or the molar ratio of the alkylene oxide to the cyclic anhydride is 0.8-2.0:1; Preferably, the organic solvent 4 includes any one of 1,4-dioxane, toluene, n-hexane, cyclohexane, and ethylene dichloride; Preferably, the reaction comprises the following conditions: the reaction temperature is 35-150° C., preferably 100-130° C.; and / or the reaction time is 1-15 h; and / or the pressure of carbon dioxide is 0.3-3 MPa.

8. The method according to claim 7, characterized in that The cyclic anhydride is selected from any one of the cyclic anhydrides of the following structures:

9. The method according to claim 7 or 8, characterized in that: The alkylene oxide is selected from any one of the alkylene oxides of the following structures:

10. The method according to any one of claims 7 to 9, characterized in that: The number average molecular weight of the terpolymer is ≥3.0 kg / mol, preferably 3.0-100.0 kg / mol; and / or the molecular weight distribution of the terpolymer is ≤1.5, preferably 1.1-1.5.

Images