Narrow molecular weight distribution PVP copolymer and preparation method therefor and use thereof

Abstract

The present application provides a narrow molecular weight distribution PVP copolymer, and a preparation method therefor and a use thereof. The PVP copolymer has the structure represented by formula I. In the present application, NVP monomer and allyl polyoxyethylene ether are subjected to a copolymerization reaction in a redox system, and a sulfonating agent is then added to the resulting copolymer reaction solution to perform sulfonation treatment of the terminal hydroxyl groups, thereby obtaining the PVP copolymer. The present application utilizes the chain transfer effect of allyl polyether to achieve effective control of the molecular weight distribution of the PVP copolymer, and performs strongly polar ionized end-group treatment to improve the segment uniformity of the PVP copolymer. The spatial steric hindrance of the polyether side chains and the charge repulsion of the ionic groups significantly improve the adequacy of chain extension of PVP in the casting solution, so as to increase the exchange rate of the casting solvent and precipitant, and obtain a membrane pore structure with uniform pore size, high porosity, and stable structure.

Description

A narrow molecular weight distribution PVP copolymer, its preparation method and application Technical Field

[0001] This application belongs to the field of polymer materials technology, and relates to a PVP copolymer, its preparation method and application, and particularly to a narrow molecular weight distribution PVP copolymer, its preparation method and application. Background Technology

[0002] Polyvinylpyrrolidone (PVP) and its copolymers are the most commonly used pore-forming agents in membrane materials. However, due to quality fluctuations between different manufacturers and batches, they often cannot fully meet the requirements of membrane manufacturers, resulting in unstable membrane material quality and abnormal fluctuations in membrane flux and rejection rate. Among these factors, the molecular weight and molecular weight distribution of PVP are the most important factors affecting the pore-forming effect.

[0003] The molecular weight and distribution of PVP and its copolymers significantly influence their performance. Therefore, precisely controlling the molecular weight distribution of PVP, especially preparing PVP copolymers with narrow molecular weight distributions, has become a research hotspot in this field. Existing technologies for preparing PVP copolymers mainly include free radical polymerization, where the molecular weight of the PVP copolymer is controlled by adjusting parameters such as monomer ratios, reaction temperature, and reaction time. However, these methods typically only control the average molecular weight of the PVP copolymer, not the precise molecular weight distribution. Other technologies use specific catalysts or chain transfer agents to control the molecular weight distribution of PVP copolymers. For example, using coupling agents to link two PVP segments together can prepare PVP copolymers with narrow molecular weight distributions. However, these methods often require specialized equipment or reagents, increasing preparation costs and process complexity. Despite the progress made in the preparation of PVP copolymers, some problems and limitations remain, restricting the application of PVP copolymers in high-end fields. Summary of the Invention

[0004] This application provides a PVP copolymer, its preparation method and application, and in particular, a narrow molecular weight distribution PVP copolymer, its preparation method and application.

[0005] In a first aspect, this application provides a PVP copolymer having the structure shown in Formula I:

[0006] Where R is selected from CH3 or H, m is an integer from 50 to 100 (e.g., 50, 55, 58, 60, 65, 68, 70, 75, 78, 80, 90, 95, 98 or 100), n is an integer from 10 to 20 (e.g., 10, 12, 14, 16, 18 or 20), p is an integer from 0 to 2 (e.g., 0, 1 or 2), and q is an integer from 10 to 20 (e.g., 10, 12, 14, 16, 18 or 20).

[0007] Preferably, the weight-average molecular weight of the PVP copolymer is 25,000 to 35,000, for example, 25,000, 28,000, 30,000, 33,000 or 35,000.

[0008] Preferably, the molecular weight distribution coefficient (PDI) of the PVP copolymer is 1.3 to 1.8, for example, 1.3, 1.4, 1.5, 1.6, 1.7 or 1.8.

[0009] Secondly, this application provides a method for preparing the PVP copolymer as described above, the method comprising the following steps:

[0010] NVP monomer and allyl polyoxyethylene ether are copolymerized in a redox system, and then a sulfonating agent is added to the resulting copolymer reaction solution to perform sulfonation treatment on the terminal hydroxyl groups, thereby obtaining the PVP copolymer.

[0011] Preferably, the molar ratio of the NVP monomer to the allyl polyoxyethylene ether is 3 to 8:1, for example, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 7:1 or 8:1.

[0012] Preferably, the allyl polyoxyethylene ether is selected from any one or a combination of at least two of allyloxy polyethylene ether (APEG), isopentenyl polyoxyethylene ether (TPEG), or isobutylene polyoxyethylene ether (HPEG).

[0013] Preferably, the reducing agent in the redox system is selected from any one or a combination of at least two of sulfites, vitamin C, or primary amines.

[0014] Preferably, the sulfite is selected from any one or a combination of at least two of ammonium sulfite, sodium sulfite, or potassium sulfite.

[0015] Preferably, the primary amine is selected from any one or a combination of at least two of N,N-dimethyltoluidine (DMA), N,N-dimethyl-p-toluidine (DMT), or diethylenetriamine.

[0016] Preferably, the redox system further includes a peroxide initiator.

[0017] Preferably, the peroxide initiator is selected from at least one of organic peroxides or inorganic peroxides.

[0018] Preferably, the organic peroxide is selected from any one or a combination of at least two of tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyacetate, or tert-butyl peroxyethylhexanoate.

[0019] Preferably, the copolymerization reaction is carried out in a solvent, and the solvent is water. This application utilizes a water-based preparation method for PVP copolymers.

[0020] Preferably, the temperature of the copolymerization reaction is 50-80°C, for example, 50°C, 60°C, 70°C or 80°C, and the copolymerization reaction is carried out by a semi-continuous dripping method, with a dripping time of 3-8 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0021] Preferably, the copolymerization reaction is carried out under nitrogen protection.

[0022] Preferably, the sulfonating agent is selected from aminosulfonic acid or chlorosulfonic acid. The purpose of sulfonation in this application is to provide ionized groups to the polymer.

[0023] Preferably, the molar ratio of the sulfonating agent to allyl polyoxyethylene ether is 0.8 to 1.2:1, for example, 0.8:1, 0.9:1, 1:1, 1.1:1 or 1.2:1.

[0024] Preferably, the sulfonation treatment is performed at a temperature of 50–90°C, such as 50°C, 60°C, 70°C, 80°C, or 90°C, for a time of 3–6 hours, such as 3 hours, 4 hours, 5 hours, or 6 hours.

[0025] This application utilizes the chain transfer effect of allyl polyether to effectively control the molecular weight distribution of PVP copolymers and performs highly polar ionized end-group treatment to improve the segment uniformity of PVP copolymers. The steric hindrance of polyether branches and the charge repulsion of ionic groups significantly improve the sufficiency of PVP chain extension in casting solution, thereby increasing the exchange rate between casting solvent and precipitant and obtaining a membrane pore structure with uniform pore size, high porosity and stable structure.

[0026] Thirdly, this application provides a membrane material pore-forming agent, which includes the PVP copolymer described above.

[0027] Fourthly, this application provides the application of the PVP copolymer or membrane material pore-forming agent as described above in water treatment membranes.

[0028] Compared with the prior art, this application has the following advantages:

[0029] The PVP copolymer of this application achieves effective control over the molecular weight distribution of the PVP copolymer. The end groups are sulfonated to improve the segment uniformity of the PVP copolymer. The steric hindrance of the polyether side chains and the charge repulsion of the ionic groups significantly improve the sufficiency of PVP chain extension in the casting solution, thereby increasing the exchange rate between the casting solvent and the precipitant and obtaining a membrane pore structure with uniform pore size, high porosity and stable structure. Detailed Implementation

[0030] The technical solution of this application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely to help understand this application and should not be regarded as specific limitations on this application.

[0031] The sources of the substances used in the following embodiments are as follows:

[0032] Allyl polyoxyethylene ether, with a molecular weight of 300-1000, was purchased from Haian Petrochemical Plant in Jiangsu Province, such as APEG300, AEPG400, APEG500, APEG700, APEG800, TPEG300, TPEG400, HPEG300 or HPEG400, etc.

[0033] Example 1

[0034] This embodiment provides a PVP copolymer, the preparation method of which includes the following steps:

[0035] (1) Under nitrogen protection, APEG300 and ammonium sulfite were added to water and stirred to form a solvent. The APEG concentration was 60%. The mixture was heated to 50°C and then a mixture of NVP and tert-butyl hydrogen peroxide was added dropwise over a period of 3 hours. The molar ratio of NVP, APEG, tert-butyl hydrogen peroxide and ammonium sulfite was 3:1:0.03:0.03.

[0036] (2) Terminal hydroxyl sulfonation

[0037] After the dropwise reaction is complete, maintain at 50°C and add aminosulfonic acid to the copolymer solution for sulfonation treatment of the hydroxyl end groups. The reaction time is 3 hours to obtain the narrow molecular weight PVP solution. After spray drying, narrow molecular weight distribution PVP is obtained, wherein the molar ratio of aminosulfonic acid to AEPG300 is 0.8:1.

[0038] Example 2

[0039] This embodiment provides a PVP copolymer, the preparation method of which includes the following steps:

[0040] (1) Under nitrogen protection, APEG700 and VC were added to water and stirred to form a solvent. The concentration of APEG was 40%. The mixture was heated to 80°C and a mixture of NVP and di-tert-butyl peroxide was added dropwise over a period of 8 hours. The molar ratio of NVP, APEG, di-tert-butyl peroxide and VC was 8:1:0.15:0.2.

[0041] (2) Terminal hydroxyl sulfonation

[0042] After the dropwise addition reaction was completed, the temperature was raised to 90°C, and aminosulfonic acid was added to the copolymer solution for sulfonation treatment of the hydroxyl-terminated groups. The reaction time was 6 hours to obtain the narrow molecular weight PVP solution, which was then spray-dried to obtain narrow molecular weight distribution PVP. The molar ratio of aminosulfonic acid to AEPG300 was 1:1.

[0043] Example 3

[0044] (1) Under nitrogen protection, HPEG400 and ammonium sulfite were added to water and stirred to form a solvent. The HPEG concentration was 50%. The mixture was heated to 70°C, and a mixture of NVP and tert-butyl peroxide was added dropwise over a period of 6 hours. The molar ratio of NVP, HPEG, tert-butyl peroxide and ammonium sulfite was 6:1:0.08:0.1.

[0045] (2) Terminal hydroxyl sulfonation

[0046] After the dropwise reaction was completed, the temperature was raised to 75°C, and chlorosulfonic acid was added to the copolymer solution for sulfonation treatment of the hydroxyl-terminated groups. The reaction time was 5 hours to obtain the narrow molecular weight PVP solution, which was then spray-dried to obtain narrow molecular weight distribution PVP. The molar ratio of aminosulfonic acid to AEPG300 was 1.2:1.

[0047] Example 4

[0048] (1) Under nitrogen protection, TPEG400 and N,N-dimethylamine were added to water and stirred to form a solvent. The concentration of TPEG was 55%. The mixture was heated to 75°C, and a mixture of NVP and tert-butyl hydrogen peroxide was added dropwise over a period of 6 hours. The molar ratio of NVP, TPEG, tert-butyl peroxide and dimethylamine was 5:1:0.10:0.15.

[0049] (2) Terminal hydroxyl sulfonation

[0050] After the dropwise addition reaction was completed, the temperature was raised to 80°C, and aminosulfonic acid was added to the copolymer solution for sulfonation treatment of the hydroxyl-terminated groups. The reaction time was 5 hours to obtain the narrow molecular weight PVP solution, which was then spray-dried to obtain narrow molecular weight distribution PVP. The molar ratio of aminosulfonic acid to AEPG300 was 1.1:1.

[0051] Comparative Example 1

[0052] Commercially available polyvinylpyrrolidone (PVP-K30) was used as a comparative example.

[0053] Comparative Example 2

[0054] The only difference from Example 1 is that the terminal hydroxyl sulfonation in step (2) is not performed.

[0055] Comparative Example 3

[0056] The only difference from Example 1 is that the molar ratio of NVP to APEG is 2:1.

[0057] Comparative Example 4

[0058] The only difference from Example 1 is that the molar ratio of NVP to APEG is 10:1.

[0059] The finished polymer specifications are summarized in Table 1.

[0060] Table 1

[0061] Application Examples 1-4 and Comparative Application Examples 1-4

[0062] Using the polymers prepared in the examples and comparative examples as porogens, a casting solution was prepared with the porogen accounting for 5% of the polyurethane membrane material. DMF was used as the solvent, and the solution was stirred and dissolved to a concentration of 20%. After vacuum degassing, the blended solution was coated onto a glass plate to form a solution membrane with a thickness of about 180 μm. The membrane was then immersed in deionized water in a coagulation bath to gel. Finally, the membrane was soaked in deionized water for 24 hours and then dried in a vacuum drying oven for membrane performance testing.

[0063] The test results are shown in Table 2.

[0064] Table 2

[0065] As can be seen from Table 2, the PVP copolymer used in this application as a pore-forming agent enables the prepared membrane material to have higher porosity (over 80%) and better membrane flux (460 g / (m²)). 2 (·h) and above).

[0066] The applicant declares that this application illustrates the PVP copolymer, its preparation method, and its application through the above embodiments, but this application is not limited to the above embodiments, that is, it does not mean that this application must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to this application, equivalent substitutions of the raw materials for the product, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this application.

Claims

1. A PVP copolymer having the following structure: Where R is selected from CH3 or H, m is an integer from 50 to 100, n is an integer from 10 to 20, p is an integer from 0 to 2, and q is an integer from 10 to 20.

2. The PVP copolymer according to claim 1, wherein, The weight-average molecular weight of the PVP copolymer is 25,000 to 35,000.

3. The PVP copolymer according to claim 1 or 2, wherein, The molecular weight distribution coefficient (PDI) of the PVP copolymer is 1.3 to 1.

8.

4. A method for preparing a PVP copolymer according to any one of claims 1-3, comprising the following steps: NVP monomer and allyl polyoxyethylene ether are copolymerized in a redox system, and then a sulfonating agent is added to the resulting copolymer reaction solution to perform sulfonation treatment on the terminal hydroxyl groups, thereby obtaining the PVP copolymer.

5. The preparation method according to claim 4, wherein, The molar ratio of the NVP monomer to the allyl polyoxyethylene ether is 3 to 8:

1. Preferably, the allyl polyoxyethylene ether is selected from any one or a combination of at least two of allyloxy polyoxyethylene ether, isopentenyl polyoxyethylene ether, or isobutylenyl polyoxyethylene ether.

6. The preparation method according to claim 4, wherein, In the redox system, the reducing agent is selected from any one or a combination of at least two of sulfites, vitamin C, or primary amines; Preferably, the sulfite is selected from any one or a combination of at least two of ammonium sulfite, sodium sulfite, or potassium sulfite; Preferably, the primary amine is selected from any one or a combination of at least two of N,N-dimethyltoluidine, N,N-dimethyl-p-toluidine, or diethylenetriamine.

7. The preparation method according to any one of claims 4-6, wherein, The redox system also includes a peroxide initiator; Preferably, the peroxide initiator is selected from at least one of organic peroxides or inorganic peroxides; Preferably, the organic peroxide is selected from any one or a combination of at least two of tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyacetate, or tert-butyl peroxyethylhexanoate. Preferably, the inorganic peroxide is selected from any one or a combination of at least two of ammonium persulfate, potassium persulfate, or sodium persulfate.

8. The preparation method according to any one of claims 4-7, wherein, The copolymerization reaction is carried out in a solvent, namely water; Preferably, the copolymerization reaction temperature is 50–80°C, the copolymerization reaction method is a semi-continuous dripping method, and the dripping time is 3–8 hours; Preferably, the copolymerization reaction is carried out under nitrogen protection.

9. The preparation method according to any one of claims 4-8, wherein, The sulfonating agent is selected from aminosulfonic acid or chlorosulfonic acid; Preferably, the molar ratio of the sulfonating agent to allyl polyoxyethylene ether is 0.8 to 1.2:1; Preferably, the sulfonation treatment is performed at a temperature of 50–90°C for 3–6 hours.

10. A membrane material pore-forming agent comprising the PVP copolymer as described in any one of claims 1-3.

11. The use of the PVP copolymer according to any one of claims 1-3 or the membrane material pore-forming agent according to claim 10 in water treatment membranes.

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