Preparation method of nonionic Gemini type temperature response block copolymer and application of nonionic Gemini type temperature response block copolymer in emulsion polymerization

Abstract

The invention discloses a preparation method of a nonionic Gemini type temperature response block copolymer and application of the nonionic Gemini type temperature response block copolymer in emulsion polymerization, and belongs to the field of application of functional polymer block copolymers. The nonionic Gemini type temperature response block copolymer comprises a hydrophilic component A, a linking group B and a temperature-sensitive component C. The hydrophilic component A comprises polyethylene glycol with the polymerization degree of 10-100, the linking group is hydroquinone, the temperature-sensitive component is poly (N-isopropylacrylamide) with the polymerization degree of 10-150, and the hydrophilic component A, the linking group B and the temperature-sensitive component C are connected through covalent bonds. The nonionic Gemini type temperature response block copolymer can be used for preparing high polymers through emulsion polymerization, can be used as an emulsifier under the condition of relatively high temperature, and can be self-demulsified under the condition of relatively low temperature. The nonionic Gemini type temperature response block copolymer can solve the problem that a demulsifier needs to be added in an emulsion polymerization process.

Description

Technical Field

[0001] The present invention belongs to the application field of functional block copolymers, particularly to a preparation method of a nonionic Gemini-type temperature-responsive block copolymer and its application in emulsion polymerization. Background Art

[0002] As a widely used industrial method for producing high molecular polymers, emulsion polymerization is known for its high efficiency and environmental friendliness, and has attracted the attention of many researchers since the early 20th century. With the sharp increase in the demand for synthetic rubber during World War II, this technology has witnessed rapid development and plays a crucial role in modern industry.

[0003] Emulsion polymerization exhibits many advantages compared to other methods such as bulk polymerization, solution polymerization, and suspension polymerization. First, using water as a solvent makes emulsion polymerization an environmentally friendly synthesis method; second, water has good heat dissipation performance, which helps to avoid local overheating and ensure the stable progress of the polymerization reaction; in addition, the emulsion polymerization reaction rate is relatively fast, enabling high production efficiency; most importantly, emulsion polymerization can obtain polymers with relatively high molecular weights, which helps to improve product performance.

[0004] However, emulsion polymerization also faces some challenges in industrial production. The most significant problem is that when the target polymer product is solid, the polymer needs to undergo a relatively complicated demulsification and separation process. To achieve effective polymer separation, chemical substances such as demulsifiers or coagulants usually need to be added. This not only increases the production cost but also generates a large amount of wastewater, imposing a burden on the environment. Therefore, it is necessary to seek low-cost and simple processes to solve the problem of complicated demulsification in emulsion polymerization, in order to reduce costs, simplify the process, and achieve an efficient and green process. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a preparation method of a nonionic Gemini-type temperature-responsive block copolymer and its application in emulsion polymerization. The nonionic Gemini-type temperature-responsive block copolymer of the present invention has temperature-controllable surface activity ability, which contributes to the self-demulsification characteristic of the emulsion polymerization process.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: A nonionic Gemini-type temperature-responsive block copolymer has the following structure: Wherein, n is an integer from 10 to 100, and m is an integer from 10 to 150.

[0007] The preparation method of the nonionic Gemini-type temperature-responsive block copolymer includes the following steps: (1) Weigh a certain amount of methoxypolyethylene glycol and dissolve it in an organic solvent. Heat it to 40 - 50 °C to completely dissolve it, and then add a certain amount of triethylamine. Then place the flask in a cold trap at -5 - 5 °C. Weigh 2-bromoisobutyryl bromide and dissolve it in an organic solvent. Dropwise add the above solution into the flask under nitrogen protection. After 10 min, place the flask at room temperature and react for 6 - 12 h. After the reaction is completed, distill the solvent with a rotary evaporator. The remaining product is purified by reprecipitation with diethyl ether and dried to obtain methoxypolyethylene glycol 2-bromoisobutyrate.

[0008] (2) Weigh a certain amount of N-isopropylacrylamide and the corresponding proportion of methoxypolyethylene glycol 2-bromoisobutyrate obtained in step (1) and dissolve them in a certain amount of mixed solvent. Weigh a certain amount of copper(I) bromide (CuBr) and pentamethyldiethylenetriamine (PMDETA) and dissolve them in a small amount of mixed solvent. Under nitrogen protection, add the latter mixed solvent to the former and react at 25 - 50 °C for 12 - 24 h. After the reaction is terminated, dialyze the reaction solution with a dialysis bag with a specific molecular weight cut-off using distilled water for 60 - 96 h. The dialysis solution is dehydrated with a freeze dryer to obtain polyethylene glycol-poly(N-isopropylacrylamide).

[0009] (3) Weigh a certain amount of hydroquinone and the corresponding proportion of polyethylene glycol-poly(N-isopropylacrylamide) obtained in step (2) and dissolve them in an organic solvent. Stir well to dissolve them, and then add a certain amount of potassium hydroxide and potassium iodide. Under nitrogen protection, react at 70 - 90 °C for 24 - 48 h. After the reaction is completed, filter. Dropwise add the filtrate into diethyl ether for reprecipitation, filter and dry to obtain a nonionic Gemini-type temperature-responsive block copolymer.

[0010] In the above step (1), the degree of polymerization of methoxypolyethylene glycol used is 10 - 100; the organic solvent used is one of chloroform, acetonitrile and acetone; the molar ratio of methoxypolyethylene glycol, triethylamine and 2-bromoisobutyryl bromide is 1:(2 - 4):(1 - 3).

[0011] In the above step (2), the mixed solvent mentioned is a mixed solvent of deionized water and dimethylformamide, and the volume ratio of deionized water to dimethylformamide is (1 - 4):1; the molar ratio of methoxypolyethylene glycol 2-bromoisobutyrate, N-isopropylacrylamide, copper(I) bromide and pentamethyldiethylenetriamine is 1:(20 - 140):(1 - 1.5):(2 - 5).

[0012] In the above step (3), the organic solvent used is one of chloroform, acetonitrile and acetone; the molar ratio of hydroquinone, polyethylene glycol-poly(N-isopropylacrylamide), potassium hydroxide and potassium iodide is 1:(2 - 5):(1 - 1.2):(0.1 - 0.5).

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The nonionic Gemini-type temperature-responsive block copolymer prepared by the present invention is a temperature-stimulus-responsive surfactant and can be used as an emulsifier for emulsion polymerization. At relatively high temperatures (greater than 40 °C), it can form stable latex particles as an emulsifier in an aqueous solvent, and at relatively low temperatures (less than 30 °C), it can demulsify.

[0014] 2. The preparation method of the nonionic Gemini-type temperature-responsive block copolymer of the present invention has the advantages of simple synthesis route, convenient operation, low material cost, no need for complex equipment, environmentally friendly solvents used, and being convenient for industrial scale-up production.

[0015] 3. The thermosensitive emulsifier of the present invention has the advantages of temperature-controllable emulsification and demulsification and recyclability in the application of emulsion polymerization self-demulsification. Description of the Drawings

[0016] Figure 1 1H NMR spectrum of the nonionic Gemini-type temperature-responsive block copolymer.

[0017] Figure 2 Micelle size distribution diagram of the aqueous solution of the nonionic Gemini-type temperature-responsive block copolymer.

[0018] Figure 3 Particle size distribution diagram of the polymethyl methacrylate obtained in Application Example 1. Detailed Embodiments

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] Example 1 (1) Weigh 7.5 g of methoxypolyethylene glycol (Macklin, average molecular weight 1500, 0.005 mol) and dissolve it in 100 mL of chloroform. Heat it to 40 °C until completely dissolved, and then add 1.5 g of triethylamine (0.015 mol). Then place the flask in a cold trap at -5 °C. Weigh 2.3 g (0.01 mol) of 2-bromoisobutyryl bromide and dissolve it in 30 mL of chloroform. Under nitrogen protection, add it dropwise to the above flask. After 10 min, place the flask at room temperature and react for 6 h. After the reaction is completed, distill the solvent using a rotary evaporator, and purify the remaining product by reprecipitation with diethyl ether. After drying, methoxypolyethylene glycol 2-bromoisobutyrate is obtained.

[0021] (2) Weigh 17 g of N-isopropylacrylamide (0.15 mol) and 8.5 g (0.005 mol) of methoxypolyethylene glycol 2-bromoisobutyrate obtained in step (1) and dissolve them in a mixed solvent of 80 mL of deionized water and dimethylformamide (volume ratio of deionized water to dimethylformamide = 3:1). Weigh 1 g (0.007 mol) of cuprous bromide and 1.73 g (0.01 mol) of pentamethyldiethylenetriamine and dissolve them in a mixed solvent of 20 mL of deionized water and dimethylformamide. Under nitrogen protection, add the latter mixed solution to the former, and react at 25 °C for 12 h. After the reaction is terminated, dialyze the reaction solution using a dialysis bag with a specific molecular weight cut-off against distilled water for 60 h, and remove water from the dialysate using a freeze dryer to obtain polyethylene glycol-poly(N-isopropylacrylamide).

[0022] (3) Weigh 0.019 g of hydroquinone (0.17 mmol) and 2.14 g (0.5 mmol) of polyethylene glycol-poly(N-isopropylacrylamide) obtained in step (2) and dissolve them in 30 mL of acetonitrile. Stir well to dissolve, then add 0.01 g (0.2 mmol) of potassium hydroxide and 0.015 g (0.09 mmol) of potassium iodide. Under nitrogen protection, react at 70 °C for 24 h. After the reaction is completed, filter, and dropwise add the filtrate into diethyl ether for reprecipitation. Filter and dry to obtain a nonionic Gemini-type temperature-responsive block copolymer.

[0023] The proton nuclear magnetic resonance spectrum of the nonionic Gemini-type temperature-responsive block copolymer obtained in this example is shown in Figure 1 .

[0024] The micelle size distribution of the aqueous solution of the nonionic Gemini-type temperature-responsive block copolymer obtained in this example is shown in Figure 2 .

[0025] Example 2 (1) Weigh 10.0 g of methoxypolyethylene glycol (Macklin, average molecular weight 2000, 0.005 mol) and dissolve it in 100 mL of chloroform. Heat it to 45 °C until it is completely dissolved, and then add 1.5 g of triethylamine (0.015 mol). Then place the flask in a cold trap at 0 °C. Weigh 2.3 g (0.01 mol) of 2-bromoisobutyryl bromide and dissolve it in 30 mL of chloroform. Dropwise add the latter into the above flask under nitrogen protection. After 10 min, place the flask at room temperature and react for 9 h. After the reaction is completed, distill the solvent with a rotary evaporator, and purify the remaining product by reprecipitation with diethyl ether. After drying, methoxypolyethylene glycol 2-bromoisobutyrate is obtained.

[0026] (2) Weigh 17 g of N-isopropylacrylamide (0.15 mol) and 11 g (0.005 mol) of methoxypolyethylene glycol 2-bromoisobutyrate obtained in step (1) and dissolve them in a mixed solvent of 80 mL of deionized water and dimethylformamide (volume ratio of deionized water to dimethylformamide = 3:1). Weigh 1 g (0.007 mol) of cuprous bromide and 1.73 g (0.01 mol) of pentamethyldiethylenetriamine and dissolve them in a mixed solvent of 20 mL of deionized water and dimethylformamide. Under nitrogen protection, add the latter mixed solution to the former, and react at 40 °C for 18 h. After the reaction is terminated, dialyze the reaction solution with a dialysis bag with a specific molecular weight cut-off against distilled water for 80 h, and remove water from the dialysate with a freeze dryer to obtain polyethylene glycol-poly(N-isopropylacrylamide).

[0027] (3) Weigh 0.019 g of hydroquinone (0.17 mmol) and 2.4 g (0.5 mmol) of polyethylene glycol-poly(N-isopropylacrylamide) obtained in step (2) and dissolve them in 30 mL of acetonitrile. Stir well to dissolve them, and then add 0.01 g (0.2 mmol) of potassium hydroxide and 0.015 g (0.09 mmol) of potassium iodide. Under nitrogen protection, react at 80 o °C for 36 h. After the reaction is completed, filter, and dropwise add the filtrate into diethyl ether for reprecipitation. Filter and dry to obtain a nonionic Gemini-type temperature-responsive block copolymer.

[0028] Example 3 (1) Weigh 5.0 g of methoxypolyethylene glycol (Macklin, average molecular weight 1000, 0.005 mol) and dissolve it in 100 mL of chloroform. Heat it to 50 o °C until it is completely dissolved, and then add 1.5 g of triethylamine (0.015 mol). Then place the flask at 5 oInto the cold trap of C; Weigh 2.3 g (0.01 mol) of 2-bromo-2-methylpropionyl bromide and dissolve it in 30 mL of chloroform. Under nitrogen protection, add it dropwise to the above flask. After 10 min, place the flask at room temperature and react for 12 h. After the reaction is completed, distill the solvent with a rotary evaporator. The remaining product is purified by reprecipitation with diethyl ether and dried to obtain methoxypolyethylene glycol 2-bromo-2-methylpropionate.

[0029] (2) Weigh 17 g of N-isopropylacrylamide (0.15 mol) and 6.0 g (0.005 mol) of methoxypolyethylene glycol 2-bromo-2-methylpropionate obtained in step (1) and dissolve them in 80 mL of a mixed solvent of deionized water and dimethylformamide (volume ratio of deionized water to dimethylformamide = 3:1). Separately, weigh 1 g (0.007 mol) of cuprous bromide and 1.73 g (0.01 mol) of pentamethyldiethylenetriamine and dissolve them in 20 mL of a mixed solvent of deionized water and dimethylformamide. Under nitrogen protection, add the latter mixed solution to the former, and react at 50 o C for 24 h. After the reaction is terminated, dialyze the reaction solution with a dialysis bag with a specific cut-off molecular weight against distilled water for 96 h, and remove water from the dialysate with a freeze dryer to obtain polyethylene glycol-poly(N-isopropylacrylamide).

[0030] (3) Weigh 0.019 g of hydroquinone (0.17 mmol) and 1.925 g (0.5 mmol) of polyethylene glycol-poly(N-isopropylacrylamide) obtained in step (2) and dissolve them in 30 mL of acetonitrile. Stir well to dissolve them, then add 0.01 g (0.2 mmol) of potassium hydroxide and 0.015 g (0.09 mmol) of potassium iodide. Under nitrogen protection, react at 90 o C for 48 h. After the reaction is completed, filter, and drop the filtrate into diethyl ether for reprecipitation, filter and dry to obtain a nonionic Gemini type temperature-responsive block copolymer.

[0031] Application Example 1 Weigh 0.1 g (0.023 mmol) of the nonionic Gemini type temperature-responsive block copolymer prepared in Example 1 of the present invention and 10 g (0.10 mol) of methyl methacrylate monomer and add them to 40 mL of deionized water. Preheat to 50 o C under stirring to form an emulsion. Separately, add 0.15 g (0.00054 mol) of initiator potassium persulfate and 10 mL of deionized water to a 50 mL beaker, stir to dissolve it completely and then add it to the above solution. Under nitrogen protection, react the above emulsion at 70 o C for 6 h; After the reaction is aborted, place the emulsion at 0 o C to cool it rapidly. After the supernatant is clarified, pour out the supernatant and at 60o After drying at C, the product polymethyl methacrylate was obtained.

[0032] The particle size distribution diagram of the polymethyl methacrylate obtained in this application example is shown in Figure 3 .

[0033] Application Example 2 Weigh 0.1 g (0.023 mmol) of the nonionic Gemini type temperature-responsive block copolymer prepared in Example 1 of the present invention and 10 mL (0.09 mol) of styrene monomer from which the polymerization inhibitor has been removed, add them to 40 mL of deionized water, and preheat to 50 o C to form an emulsion. Separately, add 0.15 g (0.00054 mol) of initiator potassium persulfate and 10 mL of deionized water to a 50 mL beaker, stir to completely dissolve it, and then add the above solution. Under nitrogen protection, the above emulsion reacts at 70 o C for 6 h; after the reaction is terminated, place the emulsion at 20 o C to rapidly cool it. After the supernatant is clarified, pour out the supernatant and dry it at 60 o C to obtain the product polystyrene.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify the specific implementation methods of the present invention or make equivalent replacements. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention is within the scope of the claims of the present invention.

Claims

1. A nonionic Gemini-type temperature-responsive block copolymer, characterized in that: The structure is as follows: Wherein, n is an integer from 10 to 100, and m is an integer from 10 to 150.

2. The preparation method of the nonionic Gemini type temperature-responsive block copolymer according to claim 1, characterized in that: It includes the following steps: (1) Weigh a certain amount of methoxypolyethylene glycol and dissolve it in an organic solvent. Heat it to 40-50 o °C until it is completely dissolved. Then add a certain amount of triethylamine, and place it in a cold trap at -5-5 o °C. Weigh 2-bromoisobutyryl bromide and dissolve it in an organic solvent. Under nitrogen protection, slowly add it dropwise to the above reaction system. After 10 min, place the reaction system at room temperature and react for 6-12 h. When the reaction is completed, distill the solvent with a rotary evaporator. The remaining product is purified by reprecipitation with diethyl ether and dried to obtain methoxypolyethylene glycol 2-bromoisobutyrate; (2)Weigh a certain amount of N-isopropylacrylamide and the polyethylene glycol monomethyl ether 2-bromo isobutyrate obtained in step (1) and dissolve them in a certain amount of mixed solvent. Weigh another certain amount of cuprous bromide CuBr and pentamethyldiethylenetriamine PMDETA and dissolve them in a small amount of mixed solvent. Under nitrogen protection, mix the two solutions and react at 25-50 o °C for 12-24 h; after the reaction is terminated, use a dialysis bag with a specific molecular weight cut-off to dialyze with distilled water for 60-96 h, and use a freeze dryer to remove water from the dialysis solution to obtain polyethylene glycol-poly(N-isopropylacrylamide); (3) Weigh a certain amount of hydroquinone and the polyethylene glycol-poly(N-isopropylacrylamide) obtained in step (2), dissolve them in an organic solvent, stir well to dissolve, then add a certain amount of potassium hydroxide and potassium iodide, and react at 70-90 o °C for 24-48 h. After the reaction is completed, filter, and slowly drop the filtrate into diethyl ether for reprecipitation, then filter and dry to obtain a nonionic Gemini-type temperature-responsive block copolymer.

3. The preparation method of the nonionic Gemini type temperature-responsive block copolymer according to claim 2, characterized in that: The degree of polymerization of the methoxypolyethylene glycol used in step (1) is from 10 to 100.

4. The preparation method of the nonionic Gemini type temperature-responsive block copolymer according to claim 2, characterized in that: The organic solvent used in step (1) is one of chloroform, acetonitrile and acetone.

5. The preparation method of the non-ionic Gemini type temperature-responsive block copolymer according to claim 2, characterized in that: The molar ratio of the methoxypolyethylene glycol, triethylamine and 2-bromoisobutyryl bromide used in step (1) is 1:(2 - 4):(1 - 3).

6. The preparation method of the non-ionic Gemini type temperature-responsive block copolymer according to claim 2, characterized in that: The mixed solvent described in step (2) is a mixed solvent of deionized water and dimethylformamide, and the volume ratio of deionized water to dimethylformamide is (1 - 4):

1.

7. The preparation method of the nonionic Gemini type temperature-responsive block copolymer according to claim 2, wherein: The molar ratio of the methoxypolyethylene glycol 2-bromoisobutyrate, N-isopropylacrylamide, cuprous bromide and pentamethyldiethylenetriamine used in step (2) is 1:(20 - 140):(1 - 1.5):(2 - 5).

8. The preparation method of the nonionic Gemini-type temperature-responsive block copolymer according to claim 2, wherein: The organic solvent used in step (3) is one of chloroform, acetonitrile and acetone.

9. The preparation method of the nonionic Gemini type temperature-responsive block copolymer according to claim 2, wherein: The molar ratio of hydroquinone, polyethylene glycol-poly(N-isopropylacrylamide), potassium hydroxide and potassium iodide used in step (3) is 1:(2 - 5):(1 - 1.2):(0.1 - 0.5).

10. The application of the nonionic Gemini type temperature-responsive block copolymer according to claim 1 in emulsion polymerization.

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