PVP (Polyvinyl Pyrrolidone) copolymer with narrow molecular weight distribution as well as preparation method and application thereof

Abstract

The invention provides a narrow-molecular-weight-distribution PVP copolymer and a preparation method and application thereof.The PVP copolymer has the structure shown in the formula I. According to the narrow-molecular-weight-distribution PVP copolymer, an NVP monomer and allyl polyoxyethylene ether are subjected to a copolymerization reaction in a redox system, then a sulfonating reagent is added into an obtained copolymer reaction solution for sulfonating terminal hydroxyl groups, and the narrow-molecular-weight-distribution PVP copolymer is obtained. The PVP copolymer is obtained. The molecular weight distribution of the PVP copolymer is effectively regulated and controlled by utilizing the chain transfer effect of allyl polyether, strong-polarity ionized end group treatment is carried out, the chain segment uniformity of the PVP copolymer is improved, the sufficiency of chain extension of PVP in a membrane casting solution is remarkably improved through steric hindrance of polyether branched chains and charge repulsion of ionic groups, and the membrane casting efficiency is improved. The exchange rate of a membrane casting solvent and a precipitator is improved, and a membrane pore structure with uniform pore diameter, high pore diameter ratio and stable structure is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and relates to a PVP copolymer and a preparation method and application thereof, and in particular to a narrow molecular weight distribution PVP copolymer and a preparation method and application thereof. Background Art

[0002] Polyvinylpyrrolidone (PVP) and its copolymers are the most commonly used pore-forming agents for membrane materials. However, due to quality fluctuations among different manufacturers and batches, they often cannot fully or partially meet the requirements of membrane companies, resulting in unstable quality of membrane materials, abnormal fluctuations in membrane flux and retention rate, etc. Among them, 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 have an important influence on their performance. Therefore, how to accurately control the molecular weight distribution of PVP, especially to prepare PVP copolymers with narrow molecular weight distribution, has become a research hotspot in this field. In the existing technology, the method for preparing PVP copolymers mainly includes free radical polymerization, and the molecular weight of PVP copolymers is controlled by adjusting the ratio of monomers, reaction temperature, reaction time and other parameters. However, these methods can usually only control the average molecular weight of PVP copolymers, but cannot accurately control the molecular weight distribution. In addition, there are some technologies that control the molecular weight distribution of PVP copolymers by using specific catalysts or chain transfer agents. For example, two PVP segments are connected together using a coupling agent to prepare PVP copolymers with narrow molecular weight distribution. However, these methods often require the use of special equipment or reagents, which increases the preparation cost and process complexity. Although the existing technology has made certain progress in the preparation of PVP copolymers, there are still some problems and limitations that restrict the application of PVP copolymers in high-end application fields. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a PVP copolymer and a preparation method and application thereof, and in particular to provide a narrow molecular weight distribution PVP copolymer and a preparation method and application thereof.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In one aspect, the present invention provides a PVP copolymer having a structure as shown in the following formula I:

[0007]

[0008] Wherein R is selected from CH3 or H, m is an integer from 50 to 100 (for example, 50, 55, 58, 60, 65, 68, 70, 75, 78, 80, 90, 95, 98 or 100, etc.), n is an integer from 10 to 20 (for example, 10, 12, 14, 16, 18 or 20, etc.), p is an integer from 0 to 2 (for example, 0, 1 or 2), and q is an integer from 10 to 20 (for example, 10, 12, 14, 16, 18 or 20, etc.).

[0009] 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.

[0010] Preferably, the molecular weight distribution index 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.

[0011] On the other hand, the present invention provides a method for preparing the PVP copolymer as described above, the preparation method comprising the following steps:

[0012] The NVP monomer and allyl polyoxyethylene ether are copolymerized in a redox system, and then a sulfonation agent is added to the obtained copolymer reaction solution to perform sulfonation treatment on the terminal hydroxyl groups to obtain the PVP copolymer.

[0013] 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.

[0014] Preferably, the allyl polyoxyethylene ether is selected from any one or a combination of at least two of allyloxy polyoxyethylene ether (APEG), isopentanol polyoxyethylene ether (TPEG) or isobutylene alcohol polyoxyethylene ether (HPEG).

[0015] Preferably, the reducing agent in the redox system is selected from any one of sulfite, vitamin C or primary amine, or a combination of at least two thereof.

[0016] Preferably, the sulfite is selected from any one of ammonium sulfite, sodium sulfite or potassium sulfite, or a combination of at least two thereof.

[0017] Preferably, the primary amine is selected from any one of N,N-dimethyltoluidine (DMA), N,N-dimethyl-p-toluidine (DMT) or diethylenetriamine, or a combination of at least two thereof.

[0018] Preferably, the redox system further comprises a peroxide initiator.

[0019] Preferably, the peroxide initiator is selected from at least one of an organic peroxide or an inorganic peroxide.

[0020] Preferably, the organic peroxide is selected from any one of tert-butyl hydroperoxide, di-tert-butyl peroxide, tert-butyl perbenzoate, tert-butyl peroxyacetate or tert-butyl peroxyethylhexanoate, or a combination of at least two thereof.

[0021] Preferably, the copolymerization reaction is carried out in a solvent, and the solvent is water. The present invention utilizes a water-based preparation method of PVP copolymers.

[0022] Preferably, the copolymerization reaction temperature is 50-80°C, for example, 50°C, 60°C, 70°C or 80°C, and the copolymerization reaction mode is semi-continuous dropwise addition, and the dropwise addition time is 3-8 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours.

[0023] Preferably, the copolymerization reaction is carried out under nitrogen protection.

[0024] Preferably, the sulfonating agent is selected from aminosulfonic acid or chlorosulfonic acid. The sulfonation treatment is carried out in the present invention to provide ionized groups to the polymer.

[0025] Preferably, the molar ratio of the sulfonated reagent to the 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.

[0026] Preferably, the sulfonation treatment is carried out at a temperature of 50 to 90° C., such as 50° C., 60° C., 70° C., 80° C. or 90° C., and for a time of 3 to 6 hours, such as 3 hours, 4 hours, 5 hours or 6 hours.

[0027] The present invention utilizes the chain transfer effect of allyl polyether to achieve effective regulation of the molecular weight distribution of the PVP copolymer, and performs strong polar ionized end group treatment to improve the segment uniformity of the PVP copolymer. The sufficiency of the chain extension of PVP in the casting solution is significantly improved through the steric hindrance of the polyether side chains and the charge repulsion of the ionic groups, so as to increase the exchange rate of the casting solvent and the precipitant, and obtain a membrane pore structure with uniform pore size, high aperture ratio and stable structure.

[0028] In another aspect, the present invention provides a membrane material porogen, wherein the membrane material porogen comprises the PVP copolymer as described above.

[0029] In another aspect, the present invention provides a use of the above-mentioned PVP copolymer or membrane material porogen in a water treatment membrane.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The PVP copolymer of the present invention realizes effective regulation of the molecular weight distribution of the PVP copolymer, and the end groups thereof are subjected to sulfonation treatment 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 the chain extension of the PVP in the casting solution, so as to increase the exchange rate of the casting solvent and the precipitant, and obtain a membrane pore structure with uniform pore size, high aperture ratio and stable structure. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0033] The sources of substances used in the following examples are as follows:

[0034] Allyl polyoxyethylene ether, molecular weight selected 300-1000, purchased from Hai'an Petrochemical Plant, Jiangsu Province, such as APEG300, AEPG400, APEG500, APEG700, APEG800, TPEG300, TPEG400, HPEG300, HPEG400, etc.

[0035] Example 1

[0036] This embodiment provides a PVP copolymer, and the preparation method thereof comprises the following steps:

[0037] (1) Under nitrogen protection, APEG300 and ammonium sulfite were added to the stirred solvent in water, the APEG concentration was 60%, heated to 50°C, and NVP and tert-butyl hydroperoxide mixed solution were added dropwise for 3 hours. The molar ratio of NVP, APEG, tert-butyl hydroperoxide and ammonium sulfite was 3:1:0.03:0.03.

[0038] (2) Sulfonation of terminal hydroxyl groups

[0039] After the dropwise reaction was completed, the temperature was maintained at 50° C. and aminosulfonic acid was added to the copolymer solution to carry out sulfonation treatment of the hydroxyl end groups. The reaction time was 3 hours to obtain the narrow molecular weight PVP solution, which was spray-dried to obtain a narrow molecular weight distribution PVP, wherein the molar ratio of aminosulfonic acid to AEPG300 was 0.8:1.

[0040] Example 2

[0041] This embodiment provides a PVP copolymer, and the preparation method thereof comprises the following steps:

[0042] (1) Under nitrogen protection, APEG700 and VC were added to the stirred solvent in water, the APEG concentration was 40%, heated to 80°C, and NVP and di-tert-butyl peroxide mixed solution were added dropwise for 8 hours. The molar ratio of NVP, APEG, di-tert-butyl peroxide, and VC was 8:1:0.15:0.2.

[0043] (2) Sulfonation of terminal hydroxyl groups

[0044] After the dropwise reaction is completed, the temperature is raised to 90°C, and aminosulfonic acid is added to the copolymer solution to perform sulfonation treatment on the hydroxyl end groups. The reaction time is 6 hours to obtain the narrow molecular weight PVP solution and the narrow molecular weight distribution PVP after spray drying. The molar ratio of aminosulfonic acid to AEPG300 is 1:1.

[0045] Example 3

[0046] Under nitrogen protection, HPEG400 and ammonium sulfite were added to the stirred solvent in water, the HPEG concentration was 50%, heated to 70°C, and NVP and tert-butyl perbenzoate mixed solution were added dropwise for 6 hours. The molar ratio of NVP, HPEG, tert-butyl perbenzoate and ammonium sulfite was 6:1:0.08:0.1.

[0047] (2) Sulfonation of terminal hydroxyl groups

[0048] After the dropwise reaction was completed, the temperature was raised to 75°C, and chlorosulfonic acid was added to the copolymer solution to perform sulfonation treatment on the hydroxyl end groups. The reaction time was 5 hours to obtain the narrow molecular weight PVP solution and the narrow molecular weight distribution PVP after spray drying. The molar ratio of aminosulfonic acid to AEPG300 was 1.2:1.

[0049] Example 4

[0050] Under nitrogen protection, TPEG400 and N,N-dimethylbenzene were added to the stirred solvent in water, the TPEG concentration was 55%, heated to 75°C, and NVP and tert-butyl hydroperoxide mixed solution were added dropwise for 6 hours. The molar ratio of NVP, TPEG, tert-butyl peroxide and dimethylbenzene was 5:1:0.10:0.15.

[0051] (2) Sulfonation of terminal hydroxyl groups

[0052] After the dropwise reaction was completed, the temperature was raised to 80°C, and aminosulfonic acid was added to the copolymer solution to perform sulfonation treatment on the hydroxyl end groups. The reaction time was 5 hours to obtain the narrow molecular weight PVP solution and the narrow molecular weight distribution PVP after spray drying. The molar ratio of aminosulfonic acid to AEPG300 was 1.1:1.

[0053] Comparative Example 1

[0054] Commercially available polyvinyl pyrrolidone (PVP-K30) was used as a comparative example.

[0055] Comparative Example 2

[0056] The only difference from Example 1 is that the sulfonation of the terminal hydroxyl groups in step (2) is not carried out.

[0057] Comparative Example 3

[0058] The only difference from Example 1 is that the molar ratio of NVP to APEG is 2:1.

[0059] Comparative Example 4

[0060] The only difference from Example 1 is that the molar ratio of NVP to APEG is 10:1.

[0061] The indicators of the finished polymer are summarized in Table 1.

[0062] Table 1

[0063] Group Number average molecular weight Weight average molecular weight Molecular weight distribution PDI Example 1 21500 29100 1.35 Example 2 17500 30600 1.75 Example 3 20300 31400 1.55 Example 4 22500 33700 1.50 Comparative Example 1 8400 32800 3.90 Comparative Example 2 18900 24800 1.31 Comparative Example 3 16300 22800 1.40 Comparative Example 4 31300 68800 2.20

[0064] Application Examples 1-4 and Comparative Examples Application Examples 1-4

[0065] The polymer prepared in the embodiment and the comparative example was used as a porogen, and a casting solution was prepared at a ratio of 5% of the porogen to the membrane material polyurethane. DMF was used as a solvent and stirred to dissolve into a casting solution with a concentration of 20%. After vacuum degassing, the blended solution was scraped on a glass plate to form a solution film with a thickness of about 180 μm, and then the membrane was immersed in a coagulation bath of deionized water to gelate into a film. Finally, the membrane was immersed in deionized water for 24 hours, and then dried in a vacuum drying oven for membrane performance testing.

[0066] The test results are shown in Table 2.

[0067] Table 2

[0068]

[0069]

[0070] It can be seen from Table 2 that the PVP copolymer of the present invention as a porogen can make the prepared membrane material have a higher porosity (more than 80%) and a better membrane flux (460 g / (m 2 .h) above).

[0071] The applicant declares that the present invention illustrates the PVP copolymer and its preparation method and application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A PVP copolymer, characterized in that: The PVP copolymer has the following structure: Wherein R is selected from CH3 or H, m is an integer of 50 to 100, n is an integer of 10 to 20, p is an integer of 0 to 2, and q is an integer of 10 to 20.

2. The PVP copolymer according to claim 1, characterized in that 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, characterized in that The molecular weight distribution coefficient PDI of the PVP copolymer is 1.3-1.

8.

4. The method for preparing the PVP copolymer according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: The NVP monomer and allyl polyoxyethylene ether are copolymerized in a redox system, and then a sulfonation agent is added to the obtained copolymer reaction solution to perform sulfonation treatment on the terminal hydroxyl groups to obtain the PVP copolymer.

5. The preparation method according to claim 4, characterized in that: 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 of allyloxy polyoxyethylene ether, isopentanol polyoxyethylene ether and isobutylene alcohol polyoxyethylene ether, or a combination of at least two thereof.

6. The preparation method according to claim 4, characterized in that: The reducing agent in the redox system is selected from any one or a combination of at least two of sulfite, vitamin C or primary amine; 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 of N,N-dimethylbenzene idine, N,N-dimethyl-p-toluidine or diethylenetriamine, or a combination of at least two thereof.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The redox system also includes a peroxide initiator; Preferably, the peroxide initiator is selected from at least one of an organic peroxide or an inorganic peroxide; 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 perbenzoate, tert-butyl peroxyacetate or tert-butyl peroxyethylhexanoate; Preferably, the inorganic peroxide is selected from any one of ammonium persulfate, potassium persulfate or sodium persulfate, or a combination of at least two thereof.

8. The preparation method according to any one of claims 4 to 7, characterized in that: The copolymerization reaction is carried out in a solvent, and the solvent is water; Preferably, the copolymerization reaction temperature is 50-80°C, the copolymerization reaction mode is semi-continuous dropwise addition, and the dropwise addition time is 3-8 hours; Preferably, the copolymerization reaction is carried out under nitrogen protection; Preferably, the sulfonating agent is selected from aminosulfonic acid or chlorosulfonic acid; Preferably, the molar ratio of the sulfonated reagent to the allyl polyoxyethylene ether is 0.8 to 1.2:1; Preferably, the sulfonation treatment is carried out at a temperature of 50 to 90° C. and for a time of 3 to 6 hours.

9. A membrane material porogen, characterized in that: The membrane material porogen comprises the PVP copolymer according to any one of claims 1 to 3.

10. Use of the PVP copolymer according to any one of claims 1 to 3 or the membrane material porogen according to claim 9 in a water treatment membrane.

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