CN106492660B - Temperature response PVDF semi-interpenetrating network polymer film and preparation method thereof - Google Patents

Abstract

The invention relates to a temperature-responsive PVDF semi-interpenetrating network polymer film and a preparation method thereof, including the following processes: (1) polymerizing a temperature-responsive monomer and PVDF in a DMF organic solvent to obtain a semi-interpenetrating network polymer; (2) uniformly dispersing the obtained semi-interpenetrating network polymer and porogen in an organic solvent to obtain a casting liquid; (3) scraping the obtained casting liquid on a clean and flat glass plate to form a liquid film with a glass rod , and then phase-inverted into a film in a coagulation bath. The temperature-responsive PVDF semi-interpenetrating network polymer membrane prepared by the invention has good hydrophilicity and high membrane porosity; has obvious dependence on temperature, and the flux varies with temperature in the range of 200-2000L/m ² under 0.1MP. h, the retention rate of bovine serum albumin can reach more than 85%, and it has the excellent performance of large flux and high retention.

Description

A kind of temperature-responsive PVDF semi-interpenetrating network polymer film and preparation method thereof

technical field

The invention belongs to the field of temperature-responsive polymer films, and particularly relates to a preparation method of a semi-interpenetrating network temperature-responsive polymer film.

Background technique

Polymer separation membrane has the advantages of high separation efficiency, low energy consumption and simple operation, and has become one of the main means of separation and purification. However, the rapidly developing membrane separation process has put forward more new requirements for the physical, chemical properties and functionalization of membrane materials, resulting in the preparation of new membrane separation materials by new technologies and new methods, which has become the latest research hotspot.

Polyvinylidene fluoride (PVDF) is a crystalline polymer with excellent anti-aging and anti-ultraviolet properties. It is not corroded by acids, alkalis, strong oxidants, etc. at room temperature. It is a comprehensive separation membrane material, which has been widely used in medical, water treatment, petrochemical, food industry and other fields. However, pure PVDF membranes do not have intelligent separation properties, and it has attracted great interest in intelligently modifying them to give them sensitive properties such as pH, temperature, and ionic strength.

From the current literature reports, the preparation of responsive PVDF membrane mainly includes two modification methods: blending and grafting. The functional components in the membrane materials prepared by blending modification are easy to be lost during the separation process, which will lead to the decrease of membrane performance. Grafting modification mainly includes surface chemical modification, radiation grafting modification, plasma modification and other methods. The surface chemical modification and irradiation grafting process is complex, and the conditions are harsh, and it is not easy to achieve large-scale production; the plasma modification surface treatment efficiency is low, the equipment is complex, and the modification effect gradually decays with time. Therefore, it is a new need to seek simple, convenient, reliable and low-cost modification methods.

The semi-interpenetrating network polymerization technology has the advantages of simple preparation and easy realization of continuous industrial production. The obtained semi-interpenetrating network polymer is composed of an uncrosslinked linear polymer interspersed in another crosslinked polymer The network structure polymer formed. Unlike blends, the two polymers still have their own phases in the semi-interpenetrating network polymer structure; also unlike graft copolymers, there is no chemical bond between the two polymers in the semi-interpenetrating network polymer structure. . The polymer with this structure has a uniform composition, is not easily damaged during use, and has stable performance. The present invention uses this technology to modify PVDF to prepare a temperature-responsive PVDF semi-interpenetrating network polymer film. The membrane has good hydrophilicity, temperature sensitivity and stability, high water flux and high protein retention capacity.

SUMMARY OF THE INVENTION

The purpose of the present invention is to prepare a temperature-responsive PVDF membrane by a novel modification method. The invention provides a temperature-responsive PVDF semi-interpenetrating network polymer film and a preparation method thereof. The temperature-responsive high molecular cross-linked polymer and linear polyvinylidene fluoride (PVDF) in the film of the present invention form a semi-interpenetrating network structure, so that the film has lasting stability during use. The membrane of the invention has large flux, high rejection rate, and temperature responsiveness; at the same time, the membrane has good hydrophilicity and can obviously improve the anti-pollution performance.

The technical solution of the present invention to solve the technical problem of the product preparation method is: designing a preparation method of a temperature-responsive PVDF semi-interpenetrating network polymer film, including the synthesis of the semi-interpenetrating network polymer and the preparation of the film, including the following steps :

(1) Preparation of temperature-responsive PVDF semi-interpenetrating network polymer: vinylidene fluoride (PVDF), temperature-responsive monomer, N,N-methylenebisacrylamide (MBA), azobisisobutyronitrile (AIBN) ) is dissolved in the organic solvent DMF, polymerized and cross-linked under nitrogen protection, centrifuged, cleaned and dried to obtain a temperature-responsive PVDF semi-interpenetrating network polymer; the temperature-responsive monomer is N-isopropyl propylene One of N,N-dimethylacrylamide (NIPAM) or N,N-dimethylacrylamide (PDMAAm).

(2) Preparation of film casting liquid: uniformly disperse the temperature-responsive PVDF semi-interpenetrating network polymer and porogen obtained in step (1) in an organic solvent, and vacuum defoaming to obtain a film casting liquid; the organic solvent is N , one of N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), and N-methylpyrrolidone (NMP).

(3) Preparation of temperature-responsive PVDF semi-interpenetrating network polymer film: the film casting liquid obtained in step (2) is scraped with a glass rod on a clean and flat glass plate to form a liquid film, and phase-inverted into a film in a coagulation bath , the coagulation bath is distilled water or 90-95% ethanol aqueous solution.

The preparation method of the temperature-responsive PVDF semi-interpenetrating network polymer film designed in the present invention is made by scraping polyvinylidene fluoride (PVDF) modified by a temperature-responsive cross-linked polymer. The first advantage is that the temperature-responsive monomer is cross-linked and polymerized in the presence of PVDF to form a semi-interpenetrating network structure. Compared with graft modification, this method is simple to operate and easy to achieve continuous production; In comparison, the temperature-responsive components are not easily lost during the use of the membrane, and have long-lasting stability. The second advantage is that the membrane pores can swell and shrink reversibly, effectively controlling flux and retention. The third advantage is that it has good hydrophilicity and anti-pollution properties. The fourth advantage is that the membrane has both large flux and high rejection, and is a new type of membrane separation material.

The preparation process and method of the invention are simple, can be carried out under normal pressure, all used reagents are conventional reagents, and the equipment is simple, and is easy for continuous industrial production.

Detailed ways

The invention relates to a temperature-responsive PVDF semi-interpenetrating network polymer film and a preparation method thereof. The film uses polyvinylidene fluoride (PVDF) as the main material for film formation. The temperature-responsive PVDF semi-interpenetrating network polymer is obtained by physically blending the temperature-responsive monomer with PVDF and then polymerizing and cross-linking. Film by conversion method. Its design principle is to disperse PVDF powder and temperature-responsive monomer in organic solvent DMF at the same time, and then add initiator and cross-linking agent to promote the polymerization and cross-linking of monomer in the presence of PVDF to form a semi-interpenetrating network polymer. It is then scraped into a film. The preparation method of the invention makes the temperature-responsive polymer and PVDF not easily lost during the use of the membrane, and the membrane has good stability.

The method described in the present invention is applied to the preparation of flat membranes, but is also applicable to other forms of membranes, including hollow fiber membranes, tubular membranes, and the like.

The preparation method of the temperature-responsive PVDF semi-interpenetrating network polymer film of the present invention will be further described below by way of examples.

Example 1

(1) 5g PVDF was uniformly dispersed in 80mL DMF in a three-necked flask at 70°C, and 5g N-isopropylacrylamide (NIPAM) and cross-linking agent MBA were added to 0.08g and 0.13g respectively (the mass of MBA and monomer) The ratio is 1:62.5 and 1:40), stir to form a uniform mixture, pass nitrogen for 30min; quickly add 0.08g initiator AIBN to the three-necked flask, stir and react under nitrogen atmosphere for 6h. The reactant was centrifuged for precipitation, the precipitate was vacuum-dried at 50°C for 48h, and ground into powder.

(2) adding the product obtained in step (1) into a certain amount of N,N-dimethylformamide (DMF), and keeping the solid content of the casting solution at 16%, 17%, 18%, 19%, 20%, stirred at 60°C for 2h to form a uniform casting solution, and vacuum defoamed for 30min.

(3) Pour the film casting liquid obtained in step (2) on a clean glass plate, scrape it with a glass rod to form a film, immerse it in distilled water at 25° C. to solidify to form a film, and wash off the residual solvent with distilled water. , to obtain the temperature-responsive film.

Example 2

(1) 5g PVDF was uniformly dispersed in 100mL DMF in a three-necked flask at 70°C, and then 7.5g N-isopropylacrylamide (NIPAM) and 0.12g and 0.19g of cross-linking agent MBA (MBA and monomer) were added. The mass ratio of 1:62.5 and 1:40) was stirred to form a uniform mixture, and nitrogen was passed through for 30min; 0.12g of initiator AIBN was quickly added to the three-necked flask, and the reaction was stirred for 6h under nitrogen atmosphere. The reactant was centrifuged for precipitation, the precipitate was vacuum-dried at 50°C for 48h, and ground into powder.

(2) adding the product obtained in step (1) to a certain amount of N,N-dimethylacetamide (DMAC), and maintaining the solid content of the casting solution to be 16%, 17%, 18%, 19%, 20%, stirred at 60°C for 2 hours to form a uniform casting liquid, and vacuum defoamed for 40 minutes.

(3) Pour the film casting liquid obtained in step (2) on a clean glass plate, scrape it with a glass rod to form a film, immerse it in a 95% ethanol aqueous solution at 28° C. to solidify into a film, and wash off the residue with distilled water After the solvent, the temperature-responsive membrane was obtained

Example 3

(1) 5g PVDF was uniformly dispersed in 140mL DMF in a three-necked flask at 70°C, and then 11.7g N-isopropylacrylamide (NIPAM) and 0.19g and 0.3g of cross-linking agent MBA (MBA and monomer) were added. The mass ratio of 1:62.5 and 1:40) was stirred to form a uniform mixed solution, and nitrogen was passed through for 30min; 0.19g of initiator AIBN was quickly added to the three-necked flask, and the reaction was stirred for 6h under nitrogen atmosphere. The reactant was centrifuged for precipitation, the precipitate was vacuum-dried at 50°C for 48h, and ground into powder.

(2) adding the product obtained in step (1) to a certain amount of N-methylpyrrolidone (NMP), and keeping the solid content of the casting solution at 16%, 17%, 18%, 19%, 20%, 60% Stir at ℃ for 2h to form a uniform casting liquid, and vacuum defoaming for 50min.

(3) Pour the casting liquid obtained in step (2) on a clean glass plate, scrape it with a glass rod to form a film, immerse the mold in a 90% ethanol aqueous solution at 30° C. to solidify to form a film, and wash off the residue with distilled water After the solvent, the temperature-responsive membrane was obtained.

Example 4

(1) 5g PVDF was uniformly dispersed in 200mL DMF in a three-necked flask at 75°C, and then 20g N-isopropylacrylamide (NIPAM) and cross-linking agent MBA were added to 0.32g and 0.5g respectively (the difference between MBA and monomer). The mass ratio is 1:62.5 and 1:40), and nitrogen is passed through for 30min; 0.32g of initiator AIBN is quickly added to the three-necked flask, and the reaction is stirred for 6h under nitrogen atmosphere. The reactant was centrifuged for precipitation, the precipitate was vacuum-dried at 50°C for 48h, and ground into powder.

(2) Same as Example 1

(3) Same as Example 3

Example 5

(1) 5g PVDF was uniformly dispersed in 80mL DMF in a three-necked flask at 75°C, and then 5g N,N-dimethylacrylamide (PDMAAm) and 0.08g and 0.13g of cross-linking agent MBA were added (MBA and mono The mass ratio of 1:62.5 and 1:40) was stirred to form a uniform mixture, and nitrogen was passed through for 30min; 0.08g of initiator AIBN was quickly added to the three-necked flask, and the reaction was stirred under nitrogen atmosphere for 6h. The reactant was centrifuged for precipitation, the precipitate was vacuum-dried at 50°C for 48h, and ground into powder.

(2) Same as Example 1

(3) Same as Example 1

Example 6

(1) Disperse 5g PVDF uniformly in 100mL DMF in a three-necked flask at 75°C, then add 7.5g N,N-dimethylacrylamide (PDMAAm) and 0.12g and 0.19g of cross-linking agent MBA respectively (MBA and mono The mass ratio of the mixture is 1:62.5 and 1:40)), stir to form a uniform mixed solution, pass nitrogen for 30min; quickly add 0.12g of initiator AIBN to the three-necked flask, and stir for 6h under nitrogen atmosphere. The reactant was centrifuged for precipitation, the precipitate was vacuum-dried at 50°C for 48h, and ground into powder.

(2) Same as Example 1

(3) Same as Example 3

Example 7

(1) Disperse 5g PVDF uniformly in 140mL DMF in a three-necked flask at 80°C, then add 11.7g N,N-dimethylacrylamide (PDMAAm) and 0.19g and 0.3g MBA (MBA and MBA) respectively. The mass ratio of the monomers is 1:62.5 and 1:40), stir to form a uniform mixed solution, and pass nitrogen for 30 minutes; 0.19g of initiator AIBN is quickly added to the three-necked flask, and the reaction is stirred for 6h under nitrogen atmosphere. The reactant was centrifuged for precipitation, the precipitate was vacuum-dried at 50°C for 48h, and ground into powder.

(2) Same as Example 2

(3) Same as Example 3

Example 8

(1) 5g PVDF was uniformly dispersed in 200mL DMF in a three-necked flask at 80°C, and then 20g N,N-dimethylacrylamide (PDMAAm) and crosslinking agent MBA were added at 0.32g and 0.5g respectively (MBA and mono The mass ratio of 1:62.5 and 1:40) was stirred to form a uniform mixture, and nitrogen was passed through for 30min; 0.32g of AIBN initiator was quickly added to the three-necked flask, and the reaction was stirred for 6h under nitrogen atmosphere. The reactant was centrifuged for precipitation, the precipitate was vacuum-dried at 50°C for 48h, and ground into powder.

(2) Same as Example 2

(3) Same as Example 3

Example 9

(1) Same as Example 1

(2) adding the product obtained in step (1) and the porogen F127 with the mass percentage (F127/(F127+IPN)) of 8%, 15% and 22% respectively to a certain amount of N,N-dimethylformaldehyde In the amide (DMF), keep the solid content of the casting solution at 16%-20%, stir at 60°C for 2 hours to form a clear and transparent homogeneous casting solution, and vacuum defoaming for 30 minutes.

(3) Same as Example 1

Example 10

(1) Same as Example 2

(2) adding the product obtained in step (1) and the porogen F127 with the mass percentage (F127/(F127+IPN)) of 8%, 15% and 22% respectively to a certain amount of N,N-dimethylethyl ether In the amide (DMAC), the solid content of the casting solution is 16%-20%, stirred at 60° C. for 3 hours to form a clear and transparent uniform casting solution, and vacuum defoamed for 30 minutes.

(3) Same as Example 2

Example 11

(1) Same as Example 5

(2) The product obtained in step (1) and the porogen F127 with the mass percentage (F127/(F127+IPN)) of 8%, 15% and 22% respectively were added to a certain amount of N-methylpyrrolidone (NMP) In the process, the solid content of the casting solution is 16%-20%, stirring at 60° C. for 3 hours to form a clear and transparent uniform casting solution, and vacuum defoaming for 30 minutes.

(3) Same as Example 3

Example 12

(1) Same as Example 6

(2) Same as Example 9

(3) Same as Example 1

Example 13

(1) Same as Example 3

(2) The product obtained in step (1) and the porogen F127 with the mass percentage (PEG/(PEG+IPN)) of 8%, 15% and 22% respectively were added to a certain amount of N,N-dimethylformaldehyde In the amide (DMF), keep the solid content of the casting solution at 16%-20%, stir at 60°C for 2 hours to form a clear and transparent homogeneous casting solution, and vacuum defoaming for 30 minutes. The molecular weights of PEG were 6,000, 10,000, and 20,000, respectively.

(3) Same as Example 1

Example 14

(1) Same as Example 4

(2) The product obtained in step (1) and the porogen F127 with the mass percentage (PEG/(PEG+IPN)) of 8%, 15% and 22% respectively were added to a certain amount of N,N-dimethylethyl ether In the amide (DMAC), the solid content of the casting solution is 16%-20%, stirred at 60° C. for 3 hours to form a clear and transparent uniform casting solution, and vacuum defoamed for 30 minutes. The molecular weights of PEG were 6,000, 10,000, and 20,000, respectively.

(3) Same as Example 2

Example 15

(1) Same as Example 7

(2) The product obtained in step (1) and the porogen F127 with the mass percentage (PEG/(PEG+IPN)) of 8%, 15% and 22%, respectively, were added to a certain amount of N-methylpyrrolidone (NMP) In the process, the solid content of the casting solution is 16%-20%, stirring at 60° C. for 3 hours to form a clear and transparent uniform casting solution, and vacuum defoaming for 30 minutes. The molecular weights of PEG were 6,000, 10,000, and 20,000, respectively.

(3) Same as Example 3

Example 16

(1) Same as Example 8

(2) The product obtained in step (1) and the porogen F127 with the mass percentage (PEG/(PEG+IPN)) of 8%, 15% and 22% respectively were added to a certain amount of N,N-dimethylformaldehyde In the amide (DMF)), the solid content of the casting solution is 16%-20%, stirred at 60° C. for 4 hours to form a clear and transparent homogeneous casting solution, and vacuum defoamed for 30 minutes. The molecular weights of PEG were 6,000, 10,000, and 20,000, respectively.

(3) Same as Example 3

After testing, the temperature-responsive PVDF semi-interpenetrating network polymer film prepared by the present invention has a mass ratio of the temperature-responsive polymer to PVDF of 1:1-1:4; The more the number, the higher the flux, the higher the hydrophilicity. With the increase of the pore-forming dose, the number of membrane pores increases, the pore size increases, the contact angle can be reduced from 80° to 0°, and the membrane pore size is 100°. Adjustable between -1000nm. The temperature-responsive PVDF semi-interpenetrating network polymer membrane has an obvious dependence on temperature, the flux range is between 200-2000 L/m ² h at 0.1 MP, and the rejection rate of bovine serum albumin can reach more than 85% .

The preparation method of the temperature-responsive PVDF semi-interpenetrating network polymer film proposed by the present invention has been described by the examples, and the content described herein can be modified or appropriately changed and combined without departing from the content, spirit and scope of the present invention to implement the present invention. It is particularly noted that all similar substitutions and modifications will be apparent to those skilled in the art. They are all considered to be included in the spirit, scope and content of the present invention.

Claims (7)

1. A temperature-responsive PVDF semi-interpenetrating network polymer film, characterized in that the film is formed by a temperature-responsive polymer and polyvinylidene fluoride (PVDF) semi-interpenetrating, and polyvinylidene fluoride and the temperature response The mass ratio of the polymer is 1:1-1:4, which is prepared by the following method steps: (1) Preparation of temperature-responsive PVDF semi-interpenetrating network polymer: Dissolve a certain amount of PVDF in solvent DMF, then add temperature-responsive monomer, crosslinker N,N-methylenebisacrylamide and initiator coupler Azodiisobutyronitrile, radically polymerized to obtain a temperature-responsive PVDF semi-interpenetrating network polymer; (2) Preparation of film casting solution: uniformly disperse the temperature-responsive PVDF semi-interpenetrating network polymer and porogen obtained in step (1) in an organic solvent, and vacuum defoaming for 30-50 min to obtain a film casting solution; (3) Preparation of temperature-responsive PVDF semi-interpenetrating network polymer film: the film casting liquid obtained in step (2) is scraped with a glass rod on a clean and flat glass plate to form a liquid film, and phase-inverted into a film in a coagulation bath . 2. A kind of temperature-responsive PVDF semi-interpenetrating network polymer membrane according to claim 1, characterized in that the membrane pore size can be changed by adjusting the ambient temperature, and the flux size is 200-1800L/m under 0.1MPa Adjustable between ² hours, the retention rate of bovine serum albumin is above 85%. 3. a kind of temperature-responsive PVDF semi-interpenetrating network polymer film according to claim 1, wherein the temperature-responsive polymer is poly-N-isopropylacrylamide or poly-N, N-dimethyl Acrylamide. 4 . The temperature-responsive PVDF semi-interpenetrating network polymer film according to claim 1 , wherein the temperature-responsive monomer is N-isopropylacrylamide or N,N-dimethylacrylamide. 5 . 5. a kind of temperature-responsive PVDF semi-interpenetrating network polymer film according to claim 1, characterized in that the organic solvent is N,N-dimethylformamide (DMF) or N,N-dimethylformamide One of acetamide (DMAC) or N-methylpyrrolidone (NMP). 6. a kind of temperature response PVDF semi-interpenetrating network polymer film according to claim 1, is characterized in that described porogen is oxyethylene-oxypropylene-oxyethylene triblock copolymer (F127) or poly Ethylene glycol (PEG). 7 . The temperature-responsive PVDF semi-interpenetrating network polymer membrane according to claim 1 , wherein the coagulation bath is distilled water or a 90-95% ethanol aqueous solution. 8 .