Preparation method for zn-co double metal cyanide catalyst, and catalyst and use thereof

Abstract

Disclosed is a preparation method for a Zn-Co double metal cyanide catalyst, and a catalyst and the use thereof. The preparation method comprises: first, preparing a Zn-Co double metal cyanide catalyst by reacting hexacyanocobaltic acid with zinc 2-ethylhexanoate in a methanol solvent; catalyzing the bulk ring-opening polymerization of a cyclosiloxane monomer using the Zn-Co double metal cyanide catalyst; after the completion of the reaction, adding dichloromethane to dissolve the polymerization product, and removing the catalyst by means of centrifugation; and adding the solution of the polymer in dichloromethane into a large amount of methanol, centrifuging same to obtain a polymer precipitate, and performing vacuum drying to remove methanol and a small amount of unreacted monomer, thereby obtaining the final product. In the present invention, by controlling the amount of the catalyst, the reaction temperature and the reaction time, the conversion and efficiency of the polymerization reaction can be effectively improved. The double metal cyanide catalyst of the present invention offers advantages including high catalytic activity, low dosage, non-corrosiveness, low costs and easy recovery of the catalyst. The method of the present invention enables the efficient synthesis of polysiloxanes, and is suitable for fields such as materials science and the electronics industry.

Description

Preparation method and application of Zn-Co bimetallic cyanide catalyst Technical Field

[0001] This invention relates to the field of polymer synthesis technology, specifically to a method for preparing Zn-Co bimetallic cyanide catalysts, the catalysts themselves, and their applications. Background Technology

[0002] Polysiloxanes are a class of polymers with typical organic-inorganic characteristics, their backbone consisting of alternating silicon and oxygen atoms (-Si-O-Si-). Due to the large bond angle of the Si-O-Si bonds (approximately 140°) and the ease of rotation of the Si-O bonds, polysiloxanes exhibit extremely high flexibility. These polymers possess a variety of excellent properties, including excellent thermal stability, low surface energy, high elasticity, extremely low glass transition temperature, and outstanding resistance to ozone, ultraviolet radiation, and chemical corrosion, making them widely used in defense, aerospace, automotive, construction, and textile industries.

[0003] Bimetallic cyanide catalysts (DMC) are highly efficient heterogeneous catalysts, appearing as white or light yellow powders. These catalysts utilize a bimetallic cyanide complex framework, forming complex complexes with various inorganic and organic ligands. As a catalyst for epoxy ring-opening polymerization, asymmetric catalysis, and CO2 copolymerization, DMC significantly improves reaction rates and efficiency due to its heterogeneous structure, heterogeneous properties, and tunable electronic properties. It exhibits high catalytic activity, low energy consumption, environmental friendliness, good recyclability, and a wide range of applications. Currently, DMC catalysts have been studied in the ring-opening polymerization of propylene oxide (PO), achieving good results. They significantly improve conversion rates, allow for better molecular weight control, and offer advantages such as high activity, low dosage, mild reaction conditions, non-corrosiveness, and easy recovery. However, there is currently no information on the application of bimetallic cyanide catalysts in the ring-opening polymerization of cyclosiloxanes; therefore, this invention provides a method for preparing a Zn-Co bimetallic cyanide catalyst (DMC) and its catalytic effect on the ring-opening polymerization of cyclosiloxanes, thereby realizing the application of bimetallic cyanide catalysts in the ring-opening polymerization of cyclosiloxanes. Traditional DMC catalysts are typically prepared using potassium cobalt cyanate and zinc chloride as precursors. However, during catalyst synthesis, potassium chloride byproducts are generated, which may inhibit subsequent polymerization reactions. Furthermore, the solvent used in traditional preparation methods is mainly water, and the presence of water may affect the structure of the catalyst and its catalytic performance in the ring-opening polymerization of cyclosiloxanes. This invention prepares a Zn-Co bimetallic cyanide catalyst in methanol solvent using cobalt cyanide and zinc 2-ethylhexanoate, avoiding the generation of potassium chloride and water that are detrimental to subsequent reactions during the preparation process. The DMC catalyst synthesized by this method is a heterogeneous catalyst with excellent catalytic performance. Because its core metals are the relatively inexpensive transition metals Zn and Co, which are not expensive precious metals, the synthesis process is simple, does not require high-temperature and high-pressure equipment, and uses a small amount, this catalyst has the advantages of being non-corrosive, non-polluting, low-cost, and easy to recycle. This method effectively solves the problems of equipment corrosion, environmental pollution, and difficult catalyst recovery that may be caused by traditional liquid acid catalysts in the reaction, while significantly improving reaction efficiency and product quality. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing Zn-Co bimetallic cyanide catalysts, the catalysts themselves, and their applications, so as to realize the application of bimetallic cyanide catalysts in the ring-opening polymerization of cyclosiloxanes.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for preparing a Zn-Co bimetallic cyanide catalyst includes the following steps:

[0007] (1) Dissolve potassium cobalt cyanide in distilled water at 50-55℃, add sulfuric acid dropwise to form a white solid precipitate, stir for 3-4 hours, add cold ethanol, and continue stirring for 30-40 minutes;

[0008] (2) Remove the white precipitate by centrifugation, remove the solvent from the filtrate by rotary evaporator, and further dry it completely by vacuum treatment at 60-65°C for 3-3.5 hours;

[0009] (3) Add ice-cold ethanol to form a slurry and stir overnight at -5°C. Then add ice-cold ethanol and centrifuge to obtain a pale yellow solid cobalt cyanide. Dissolve the pale yellow solid cobalt cyanide and zinc 2-ethylhexanoate in methanol and mix them quickly. Stir for 24-28 hours and separate to obtain a white gel. Dry under vacuum at 50-55°C for 24-28 hours and grind to obtain a white solid powder Zn-Co bimetallic cyanide catalyst.

[0010] Preferably, the Zn-Co bimetallic cyanide catalyst is composed of cobalt cyanic acid and zinc 2-ethylhexanoate.

[0011] Preferably, the Zn:Co molar ratio of the Zn-Co bimetallic cyanide catalyst is 3:1.

[0012] This application also provides a Zn-Co bimetallic cyanide catalyst, which is prepared by the above-described method for preparing Zn-Co bimetallic cyanide catalysts.

[0013] This application also claims a method for ring-opening polymerization of cyclosiloxanes using the above-mentioned Zn-Co bimetallic cyanide catalyst, comprising the following steps:

[0014] S1. Under anhydrous and oxygen-free conditions, 0.1wt% to 0.5wt% of Zn-Co bimetallic cyanide catalyst and cyclosiloxane monomer are added to a container;

[0015] S2. Introduce nitrogen gas and heat to 100℃~120℃ for 1.5~2 hours to carry out bulk ring-opening polymerization;

[0016] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. An excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomers in the polymer are removed by vacuum drying.

[0017] Preferably, the cyclosiloxane is hexamethylcyclotrisiloxane (D3).

[0018] Specifically, the Zn-Co bimetallic cyanide catalyst is a compound represented by Formula I;

[0019] in,

[0020] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0021] 1. Traditional liquid acid-catalyzed ring-opening polymerization of cyclosiloxanes requires cumbersome post-treatment processes such as neutralization and water washing. Furthermore, these liquid acids severely corrode equipment, pollute the environment, are difficult to operate, and have high production costs. Compared with traditional liquid acid-catalyzed ring-opening polymerization of cyclosiloxanes, this invention uses a heterogeneous bimetallic cyanide catalyst. By controlling the reaction conditions, high-conversion polysiloxanes can be prepared. This catalyst has the advantages of not corroding equipment, no environmental pollution, low cost, and easy catalyst recovery.

[0022] 2. Traditional DMC catalysts are typically prepared using potassium cobalt cyanate and zinc chloride as precursors. However, potassium chloride byproducts are generated during catalyst synthesis, which may inhibit subsequent polymerization reactions. Furthermore, the solvent used in traditional preparation methods is primarily water, and the presence of water may affect the catalyst structure and its catalytic performance in the ring-opening polymerization of cyclosiloxanes. Under conditions of 2wt%–4wt% catalyst dosage, a reaction temperature of 120°C, and a reaction time of 10 h, the ring-opening conversion rate of D3 using traditional DMC catalysts is 21.04%–25.27%, with a yield of only 5.43%–6.01%. In contrast, the DMC catalyst of this invention, with a catalyst dosage of only 0.1wt%–0.5wt%, a reaction temperature of 120°C, and a reaction time of 1.5 h, achieves a ring-opening conversion rate of 65.75%–99.54% for D3, with a yield as high as 56.16%–87.14%.

[0023] 3. This invention combines cobalt cyanide and zinc 2-ethylhexanoate in a specific ratio in methanol solvent to form a complex catalyst, avoiding the disadvantages of potassium chloride and water being mixed in the traditional DMC catalyst preparation process. The conversion rate of cyclosiloxane ring-opening polymerization is as high as 99%, and it has the advantages of low dosage, high conversion rate and high activity. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, some of the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can be made based on these drawings without creative effort.

[0025] Figure 1 is an infrared spectrum (FT-IR) image of the bimetallic cyanide catalyst of Example 1 of the present invention;

[0026] Figure 2 is an X-ray diffraction (XRD) image of the bimetallic cyanide catalyst of Example 1 of the present invention;

[0027] Figure 3 shows the nuclear magnetic resonance (NMR) data of the ring-opening polymerization of D3 catalyzed by a 0.1 wt% bimetallic cyanide catalyst in Example 1 of this invention. 1 H-NMR images;

[0028] Figure 4 shows the nuclear magnetic resonance (NMR) data of the ring-opening polymerization of D3 catalyzed by a 0.5 wt% bimetallic cyanide catalyst in Example 4 of this invention. 1 H-NMR image. Detailed Implementation

[0029] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.

[0030] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0031] Synthesis example 1

[0032] This synthetic example provides a method for preparing a Zn-Co bimetallic cyanide catalyst, comprising the following steps:

[0033] (1) Dissolve potassium cobalt cyanide in distilled water at 50°C, add sulfuric acid dropwise to form a white solid precipitate, stir for 3 hours, add cold ethanol, and continue stirring for 30 minutes.

[0034] (2) Remove the white precipitate by centrifugation, remove the solvent from the filtrate by rotary evaporator, and further dry it completely by vacuum treatment at 60°C for 3 hours.

[0035] (3) Add ice-cold ethanol to form a slurry, stir overnight at -5°C, then add ice-cold ethanol and centrifuge to obtain a pale yellow solid cobalt cyanide. Dissolve the pale yellow solid cobalt cyanide and zinc 2-ethylhexanoate separately in methanol and mix them rapidly. Stir for 24 hours and separate to obtain a white gel. Dry under vacuum at 50°C for 24 hours and grind to obtain a white solid powder Zn-Co bimetallic cyanide catalyst. The Zn:Co molar ratio of the Zn-Co bimetallic cyanide catalyst is 3:1.

[0036] Example 1

[0037] Referring to Figures 1-3, this embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0038] S1. In an anhydrous and oxygen-free glove box, add 0.1wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0039] S2. Nitrogen gas is introduced and the mixture is heated to 100°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0040] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 35.9% and the reaction yield is 28.85%.

[0041] Example 2

[0042] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0043] S1. In an anhydrous and oxygen-free glove box, add 0.2wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a 100ml two-necked reaction flask that has been dried.

[0044] S2. Nitrogen gas is introduced and the mixture is heated to 100°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0045] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 53.05% and the reaction yield is 42.78%.

[0046] Example 3

[0047] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0048] S1. In an anhydrous and oxygen-free glove box, add 0.3wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a 100ml two-necked reaction flask that has been dried.

[0049] S2. Nitrogen gas is introduced and the mixture is heated to 100°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0050] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 95.39% and the reaction yield is 77.14%.

[0051] Example 4

[0052] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0053] S1. In an anhydrous and oxygen-free glove box, add 0.5wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0054] S2. Nitrogen gas is introduced and the mixture is heated to 100°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0055] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 99.83% and the reaction yield is 82.01%.

[0056] Example 5

[0057] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0058] S1. In an anhydrous and oxygen-free glove box, add 0.1wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0059] S2. Nitrogen gas is introduced and the mixture is heated to 110°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0060] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 53.27% and the reaction yield is 45.33%.

[0061] Example 6

[0062] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0063] S1. In an anhydrous and oxygen-free glove box, add 0.2wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a 100ml two-necked reaction flask that has been dried.

[0064] S2. Nitrogen gas is introduced and the mixture is heated to 110°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0065] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 97.33% and the reaction yield is 75.53%.

[0066] Example 7

[0067] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0068] S1. In an anhydrous and oxygen-free glove box, add 0.3wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a 100ml two-necked reaction flask that has been dried.

[0069] S2. Nitrogen gas is introduced and the mixture is heated to 110°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0070] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 99.31% and the reaction yield is 84.51%.

[0071] Example 8

[0072] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0073] S1. In an anhydrous and oxygen-free glove box, add 0.5wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0074] S2. Nitrogen gas is introduced and the mixture is heated to 110°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0075] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 99.13% and the reaction yield is 86.82%.

[0076] Example 9

[0077] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0078] S1. In an anhydrous and oxygen-free glove box, add 0.1wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0079] S2. Nitrogen gas is introduced and the mixture is heated to 120°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0080] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 65.75% and the reaction yield is 56.16%.

[0081] Example 10

[0082] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0083] S1. In an anhydrous and oxygen-free glove box, add 0.2wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a 100ml two-necked reaction flask that has been dried.

[0084] S2. Nitrogen gas is introduced and the mixture is heated to 120°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0085] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 98.87% and the reaction yield is 82.32%.

[0086] Example 11

[0087] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0088] S1. In an anhydrous and oxygen-free glove box, add 0.3wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a 100ml two-necked reaction flask that has been dried.

[0089] S2. Nitrogen gas is introduced and the mixture is heated to 120°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0090] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 99.45%, and the reaction rate constant is 84.36%.

[0091] Example 12

[0092] This embodiment provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0093] S1. In an anhydrous and oxygen-free glove box, add 0.5wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0094] S2. Nitrogen gas is introduced and the mixture is heated to 120°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0095] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 99.54% and the reaction yield is 87.14%.

[0096] Comparative Example 1

[0097] This comparative example provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0098] S1. In an anhydrous and oxygen-free glove box, add 0.1wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0099] S2. Nitrogen gas is introduced and the mixture is heated to 90°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0100] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 16.24% and the reaction yield is 9.76%.

[0101] Comparative Example 2

[0102] This comparative example provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0103] S1. In an anhydrous and oxygen-free glove box, add 0.5wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0104] S2. Nitrogen gas is introduced and the mixture is heated to 90°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0105] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 23.60% and the reaction yield is 15.75%.

[0106] Comparative Example 3

[0107] This comparative example provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0108] S1. In an anhydrous and oxygen-free glove box, add 0.1wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0109] S2. Nitrogen gas is introduced and the mixture is heated to 130°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0110] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 30.76% and the reaction yield is 21.94%.

[0111] Comparative Example 4

[0112] This comparative example provides a method for ring-opening polymerization of cyclosiloxanes using the Zn-Co bimetallic cyanide catalyst prepared in Synthesis Example 1 above, comprising the following steps:

[0113] S1. In an anhydrous and oxygen-free glove box, add 0.5wt% Zn-Co bimetallic cyanide catalyst and 20g hexamethylcyclotrisiloxane (D3) to a dried 100ml two-necked reaction flask.

[0114] S2. Nitrogen gas is introduced and the mixture is heated to 130°C and kept at a constant temperature for 1.5 hours to carry out the bulk ring-opening polymerization reaction. During the reaction, samples are taken at regular intervals and analyzed by nuclear magnetic resonance 1H NMR to obtain the monomer conversion rate and yield at each sampling point.

[0115] S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. Excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomer in the polymer are removed by vacuum drying. Finally, the monomer conversion rate is 34.87% and the reaction yield is 25.62%.

[0116] Figure 3 shows the nuclear magnetic resonance spectrum of the polymethylsiloxane synthesized in Example 1. As can be seen from the spectrum, the chemical shifts of hydrogen in the product correspond one-to-one with the spectrum. The hydrogen nuclear magnetic resonance spectrum analysis shows that this product is the target product, polymethylsiloxane.

[0117] In Examples 1, 2, 3, and 4, with other conditions kept constant, the polymerization temperature was 100°C. By adjusting the amount of bimetallic cyanide catalyst, the results showed that when the catalyst content was in the range of 0.1 wt% to 0.5 wt%, the ring-opening conversion of D3 and the reaction rate increased with the increase of the catalyst amount.

[0118] In Examples 5, 6, 7, and 8, with other conditions kept constant, the polymerization temperature was 110°C. By adjusting the amount of bimetallic cyanide catalyst, the results showed that when the catalyst content was in the range of 0.1 wt% to 0.5 wt%, the ring-opening conversion of D3 and the reaction rate increased with the increase of the catalyst amount.

[0119] In Examples 9, 10, 11, and 12, with other conditions kept constant, the polymerization temperature was 120°C. By adjusting the amount of bimetallic cyanide catalyst, the results showed that when the catalyst content was in the range of 0.1 wt% to 0.5 wt%, the ring-opening conversion of D3 and the reaction rate increased with the increase of the catalyst amount.

[0120] In Examples 1, 5, and 9, with other conditions remaining constant, the catalyst content was 0.1 wt%. By adjusting the polymerization temperature, the results showed that when the polymerization temperature was in the range of 100°C to 120°C, the ring-opening conversion of D3 and the reaction rate increased with the increase of the polymerization temperature.

[0121] The examples and comparative examples show that polymerization temperatures below 100°C or above 120°C both affect the ring-opening conversion rate and reaction rate of D3.

[0122] This invention synthesizes a novel Zn-Co bimetallic cyanide catalyst in methanol solvent using cobalt cyanide and zinc 2-ethylhexanoate for the ring-opening polymerization of epoxysilanes. Compared with traditional DMC catalysts and liquid acid catalysts, this catalyst has mild polymerization conditions, high catalytic performance, short reaction time and low energy consumption, and has significant advantages over traditional methods.

[0123] Zn-Co bimetallic cyanide catalysts have high activity, require less catalyst, are low in cost, and can increase the polymerization rate in a short time. Even with a small amount of catalyst, the catalytic efficiency is still high, which can significantly improve production efficiency and save costs.

[0124] This method aligns with green chemistry principles, as the catalyst is recyclable and non-corrosive, reducing equipment damage and waste generation, resulting in a lower environmental impact. Overall, this invention offers significant technological advantages, not only improving product performance and production efficiency but also demonstrating excellent environmental friendliness. It is suitable for the preparation of high-performance polysiloxanes and related fields, and has broad application prospects.

[0125] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a Zn-Co bimetallic cyanide catalyst, characterized in that, Includes the following steps: (1) Dissolve potassium cobalt cyanide in distilled water at 50-55℃, add sulfuric acid dropwise to form a white solid precipitate, stir for 3-4 hours, add cold ethanol, and continue stirring for 30-40 minutes; (2) Remove the white precipitate by centrifugation, remove the solvent from the filtrate, and further dry it completely by vacuum treatment at 60-65°C for 3-3.5 hours; (3) Add ice-cold ethanol to form a slurry and stir overnight at -5°C. Then add ice-cold ethanol and centrifuge to obtain a pale yellow solid cobalt cyanide. Dissolve the pale yellow solid cobalt cyanide and zinc 2-ethylhexanoate in methanol and mix them quickly. Stir for 24-28 hours and separate to obtain a white gel. Dry under vacuum at 50-55°C for 24-28 hours and grind to obtain a white solid powder Zn-Co bimetallic cyanide catalyst.

2. The method for preparing the Zn-Co bimetallic cyanide catalyst according to claim 1, characterized in that, The Zn-Co bimetallic cyanide catalyst is composed of cobalt cyanic acid and zinc 2-ethylhexanoate.

3. The method for preparing the Zn-Co bimetallic cyanide catalyst according to claim 1, characterized in that, The Zn:Co molar ratio of the Zn-Co bimetallic cyanide catalyst is 3:

1.

4. A Zn-Co bimetallic cyanide catalyst, characterized in that, The catalyst was prepared using the method described in any one of claims 1 to 3 for the Zn-Co bimetallic cyanide catalyst.

5. A method for ring-opening polymerization of cyclosiloxanes using a Zn-Co bimetallic cyanide catalyst, characterized in that, A method for ring-opening polymerization of cyclosiloxanes using a Zn-Co bimetallic cyanide catalyst prepared by the method described in any one of claims 1 to 3, or a Zn-Co bimetallic cyanide catalyst as described in claim 4, comprises the following steps: S1. Under anhydrous and oxygen-free conditions, 0.1wt% to 0.5wt% of Zn-Co bimetallic cyanide catalyst and cyclosiloxane monomer are added to a container; S2. Introduce nitrogen gas and heat to 100℃~120℃ for 1.5~2 hours to carry out bulk ring-opening polymerization; S3. After the polymerization reaction is completed, polysiloxane is obtained. The obtained polysiloxane is dissolved in dichloromethane, and the solid catalyst and solution are obtained by centrifugation. An excess methanol solution is added to the solution, and the polymer precipitate is obtained by centrifugation. Then, the methanol and a small amount of unreacted monomers in the polymer are removed by vacuum drying.

6. The method for ring-opening polymerization of cyclosiloxanes using a Zn-Co bimetallic cyanide catalyst according to claim 5, characterized in that, The cyclosiloxane is hexamethylcyclotrisiloxane.

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