A polyethersulfone membrane with low protein adsorption function and its preparation method

Abstract

The present invention discloses a polyethersulfone membrane with low protein adsorption function and its preparation method. The polyethersulfone membrane comprises the following raw materials according to mass percentage: 10-30% of polyethersulfone, 3-15% of amphiphilic copolymer, 2-10% of pore former, 0.5-15% of non-solvent, and 55-75% of solvent. Through a carefully designed formulation and preparation process, the present invention successfully prepares a polyethersulfone membrane with low protein adsorption function. The addition of the amphiphilic copolymer P(PVP-r-PDMS) not only enhances the hydrophilicity and protein adsorption resistance of the membrane, but also realizes the optimization of the membrane structure through the fine regulation of the RTIPS method. Finally, a polyethersulfone hollow fiber membrane with excellent anti-fouling performance and high permeability is obtained, which has broad application prospects in the fields of hemodialysis, drug filtration, food industry, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of separation membranes, and particularly to a polyethersulfone membrane with low protein adsorption function and a preparation method thereof. Background Art

[0002] Due to the relative hydrophobicity of polyethersulfone membrane materials, they are prone to be contaminated during application, that is, non-polar solutes (such as particulate impurities, proteins or bacteria) are easily adsorbed on the membrane surface, resulting in membrane pore blockage, affecting the permeability and causing a decrease in flux. For example, in the cell perfusion culture technology, when the hydrophobic membrane material contacts with blood, non-specific proteins and non-viable cells in the blood will quickly adhere to the membrane surface, or when the decomposition products of defoamers and cell metabolites penetrate the membrane pores, adhesion and fouling occur inside the filter pores, and severe fouling will shorten the service life of the membrane. Therefore, it is crucial to improve the anti-fouling property and permeation selectivity of the membrane.

[0003] Anti-fouling membranes mainly perform hydrophilic modification on the membrane body, introducing polymers based on polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), etc., which can improve the hydrophilicity and anti-fouling property of the membrane surface. The hydrophilic molecular chain segments can form a dense water separation layer on the membrane surface to prevent the adsorption of pollutants on the membrane surface. However, due to the limited compatibility between hydrophilic PVP, PEG and other polymers and the hydrophobic membrane body, most of them are enriched on the membrane surface, with low distribution in the membrane pores, and are prone to loss during operation or fouling in the pores. Therefore, there is an urgent need to construct a separation membrane with the synergistic effect of hydrophilic anti-fouling and low surface energy fouling release to achieve stable anti-fouling performance of the membrane. Summary of the Invention

[0004] The purpose of the present invention is to provide a polyethersulfone membrane with low protein adsorption function and a preparation method thereof, to solve the problems that the hydrophilic substances have poor compatibility with the membrane body during the preparation of the above anti-fouling membrane, the distribution of hydrophilic substances in the membrane pores is less, and the loss of hydrophilic substances during the use of the anti-fouling membrane causes a decrease in anti-fouling performance.

[0005] To achieve the above purpose, the first aspect of the present invention provides a polyethersulfone membrane with low protein adsorption function, and the polyethersulfone membrane comprises the following raw materials according to mass percentage:

[0006]

[0007] Preferably, the preparation method of the amphiphilic copolymer is:

[0008] Dissolve PVP and PDMS in butyl acetate, add an initiator in a nitrogen environment, after the reaction, precipitate the polymerization product with n-hexane and dry it in an oven to obtain the amphiphilic copolymer.

[0009] Preferably, the pore-forming agent is one or more of polyethylene glycol, polyvinylpyrrolidone, lithium chloride, and polymethyl acrylate.

[0010] Preferably, the non-solvent is one or more of dipropylene glycol, tetraethylene glycol, ethylene glycol monomethyl ether, and polyvinyl alcohol.

[0011] Preferably, the solvent is one or more of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, or triethyl phosphate.

[0012] A second aspect of the present invention provides a method for preparing a polyethersulfone membrane with low protein adsorption function, comprising the following steps:

[0013] (1) Polyethersulfone, amphiphilic copolymer, pore-forming agent, non-solvent, and solvent are added to a reaction kettle in proportion, stirred and degassed to obtain a homogeneous casting solution;

[0014] (2) The homogeneous casting solution is extruded through a spinneret, enters a coagulation bath after passing through an air bath, is coagulated, traction-reeled, the membrane filaments are preliminarily solidified and formed, washed and dried to obtain a polyethersulfone membrane.

[0015] Preferably, in step (1), the solvent and the pore-forming agent are first added to the reaction kettle for stirring, then polyethersulfone and amphiphilic copolymer are added to the reaction kettle, stirred at 45-85 °C for 3-5 h, cooled to 40 °C, the non-solvent is added, and stirring is continued for 5-10 h, followed by degassing to obtain a homogeneous casting solution.

[0016] Preferably, in step (2), the temperature of the air bath is 30-60 °C, the humidity is 50-80%; the temperature of the coagulation bath is 30-60 °C; the traction speed is 2-10 m / s; and deionized water at 30-50 °C is used for washing.

[0017] Therefore, the polyethersulfone membrane with low protein adsorption function and its preparation method adopting the above structure in the present invention have the following beneficial effects:

[0018] (1) The present invention prepares an amphiphilic copolymer, which is added to the polyethersulfone matrix, can improve the performance of the membrane. Polyvinylpyrrolidone PVP in the amphiphilic copolymer provides hydrophilicity, reduces the hydrophobicity of the membrane surface, and reduces the adhesion of proteins. Polydimethylsiloxane PDMS in the amphiphilic copolymer provides hydrophobicity, combines with PVP to form an amphiphilic structure, can form a barrier to reduce the direct contact and adsorption of proteins, and improve the anti-pollution performance of the polysulfone membrane.

[0019] (2) In the present invention, the amphiphilic copolymer is used as an additive and polyethersulfone is used as the matrix material. The amphiphilic copolymer forms microphase separation in the membrane, which helps to form a uniform microstructure and improve the permeability and stability of the membrane.

[0020] (3) By precisely controlling the ratios of the solvent, non-solvent, and porogen, as well as the appropriate temperature and stirring time, the present invention ensures the uniformity and stability of the casting solution, avoids defects in the membrane, and improves the comprehensive performance of the membrane.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0022] Figure 1 It is a schematic diagram of pore size distribution (M1 is the pore size distribution of Comparative Example 1, M2 is the pore size distribution of Comparative Example 2, M3 is the pore size distribution of Example 2, and M4 is the pore size distribution of Example 1);

[0023] Figure 2 It is a SEM photograph of the cross-section of the polyethersulfone filter membrane prepared in Example 1, with a magnification of 300x;

[0024] Figure 3 It is a SEM photograph of the cross-section of the polyethersulfone filter membrane prepared in Example 1, with a magnification of 2000x;

[0025] Figure 4 It is a SEM photograph of the cross-section of the polyethersulfone filter membrane prepared in Example 2, with a magnification of 300x;

[0026] Figure 5 It is a SEM photograph of the cross-section of the polyethersulfone filter membrane prepared in Example 2, with a magnification of 2000x;

[0027] Figure 6 It is a SEM photograph of the cross-section of the polyethersulfone filter membrane prepared in Comparative Example 1, with a magnification of 300x;

[0028] Figure 7 It is a SEM photograph of the cross-section of the polyethersulfone filter membrane prepared in Comparative Example 1, with a magnification of 2000x. Detailed Embodiments

[0029] The present invention will be further described below. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the present invention is not limited to this embodiment.

[0030] Example 1

[0031] A method for preparing a polyethersulfone membrane with low protein adsorption function, comprising the following steps:

[0032] (1) Weigh 862.5 g of dimethylacetamide and 67.5 g of polyethylene glycol (8000 Da) into a reaction kettle respectively. Then add 270 g of polyethersulfone and 75 g of amphiphilic copolymer P (PVP-r-PDMS) into the reaction kettle, and stir at 80 °C for 4 h. After that, cool down to 40 °C, add 225 g of dipropylene glycol into the casting solution, continue to stir for 6 h, and let it stand for defoaming to obtain a homogeneous casting solution.

[0033] The preparation method of the amphiphilic copolymer is as follows:

[0034] Dissolve 52.5 g of PVP and 26.3 g of PDMS in 120 g of butyl acetate, add 1.2 g of initiator AIBN in a nitrogen environment, react for 12 h, precipitate the polymerization product with n-hexane, and dry it in an oven at 60 °C for 15 h to obtain the amphiphilic copolymer.

[0035] (2) The homogeneous casting solution is extruded through a spinneret, passes through an air bath at a temperature of 50 °C and a humidity of 50%, and then enters a coagulation bath at 30 °C to be solidified into a film by water coagulation bath. The drawing speed is 10 m / s. Then soak the prepared wet film in deionized water at 30 °C for cleaning, and finally dry it at a temperature of 28 °C and a humidity of 60% to obtain a polyethersulfone filter membrane.

[0036] Example 2

[0037] A preparation method of a polyethersulfone membrane with low protein adsorption function, comprising the following steps:

[0038] (1) Weigh 825 g of dimethylacetamide and 135 g of polyvinylpyrrolidone (38000 Da) into a reaction kettle respectively. Then add 225 g of polyethersulfone and 150 g of amphiphilic copolymer P (PVP-r-PDMS) into the reaction kettle, and stir at 80 °C for 4 h. After that, cool down to 35 °C, add 165 g of tetraethylene glycol into the casting solution, continue to stir for 6 h. After standing for defoaming, a homogeneous casting solution is obtained.

[0039] The preparation method of the amphiphilic copolymer is as follows:

[0040] Dissolve 59 g of PVP and 39.4 g of PDMS in 100 g of butyl acetate, add 1.6 g of initiator AIBN in a nitrogen environment, react for 12 h, precipitate the polymerization product with n-hexane, and dry it in an oven at 60 °C for 15 h to obtain the amphiphilic copolymer.

[0041] (2) The homogeneous casting solution is extruded through a spinneret, passes through an air bath at a temperature of 35°C and a humidity of 80%, and then enters a coagulation bath at 35°C where it is solidified into a film by water coagulation bath. The drawing speed is 3 m / s. Then the prepared wet film is immersed in deionized water at a temperature of 40°C for cleaning, and finally dried under the conditions of a temperature of 28°C and a humidity of 60% to obtain a polyethersulfone filter membrane.

[0042] Comparative Example 1

[0043] In this comparative example, no amphiphilic copolymer was added. The specific preparation method is as follows:

[0044] A method for preparing a polyethersulfone membrane, comprising the following steps:

[0045] (1) Weigh 729 g of dimethylacetamide and 120 g of polyvinylpyrrolidone (38000 Da) into a reaction kettle respectively. Then add 225 g of polyethersulfone into the reaction kettle, stir at 80°C for 4 h, cool down to 40°C, add 426 g of tetraethylene glycol to the casting solution, continue to stir for 6 h, and stand for defoaming to obtain a homogeneous casting solution.

[0046] (2) The homogeneous casting solution is extruded through a spinneret, passes through an air bath at a temperature of 40°C and a humidity of 80%, and then enters a coagulation bath at 40°C where it is solidified into a film by water coagulation bath. The drawing speed is 5 m / s. Then the prepared wet film is immersed in deionized water at a temperature of 40°C for cleaning, and finally dried under the conditions of a temperature of 28°C and a humidity of 60% to obtain a polyethersulfone filter membrane.

[0047] Comparative Example 2

[0048] In this comparative example, the amphiphilic copolymer was replaced with PDMS alone. The specific preparation method is as follows:

[0049] A method for preparing a polyethersulfone membrane, comprising the following steps:

[0050] (1) Weigh 756 g of dimethylacetamide and 93 g of polyvinylpyrrolidone (210000 Da) into a reaction kettle respectively. Then add 225 g of polyethersulfone and 34.5 g of PDMS into the reaction kettle, stir at 80°C for 4 h, cool down to 40°C, add 391.5 g of dipropylene glycol to the casting solution, continue to stir for 6 h, and stand for defoaming to obtain a homogeneous casting solution.

[0051] (2) The homogeneous casting solution is extruded through a spinneret, passes through an air bath at a temperature of 50°C and a humidity of 50%, and then enters a coagulation bath at 40°C where it is solidified into a film by water coagulation bath. The drawing speed is 3 m / s. Then the prepared wet film is immersed in deionized water at a temperature of 40°C for cleaning, and finally dried under the conditions of a temperature of 28°C and a humidity of 60% to obtain a polyethersulfone filter membrane.

[0052] Comparative Example 3

[0053] The difference from Example 1 is that no amphiphilic copolymer was added.

[0054] Comparative Example 4

[0055] The difference from Example 1 is that no non-solvent dipropylene glycol was added.

[0056] Comparative Example 5

[0057] The difference from Example 1 is that PVP and PDMS in the preparation of the amphiphilic copolymer were directly added to the homogeneous casting solution in step (1).

[0058] Comparative Example 6

[0059] The difference from Example 1 is that the addition amount of dimethylacetamide was 587.5 g, and the addition amount of dipropylene glycol was 500 g, where the mass percentage of dipropylene glycol added was 33.33%, and the addition amount of the non-solvent increased.

[0060] Performance Test

[0061] (1) SEM tests were carried out on the membranes prepared in Examples 1-2 and Comparative Example 1. The test results are shown in Figure 2-7 . The cross-sections of the membranes in Examples 1-2 and Comparative Example 1 both showed a sponge pore structure. The cross-section of the polyethersulfone membrane prepared in Example 1 showed a symmetric structure, with dense sponge layers on both the inner and outer surfaces. After detection, the pore size was less than 0.2 μm, and the pore size of the interpenetrating sponge body structure in the middle was about 0.2 μm, and the pore size distribution was relatively wide (as Figure 1 shown). The cross-section of the polyethersulfone membrane prepared in Example 2 showed a uniform sponge body structure, without a cortex on both the inner and outer surfaces, and the pore size distribution was relatively narrow. The cross-section of the polyethersulfone membrane prepared in Comparative Example 1 showed a gradient sponge pore structure, with a dense cortex on the outer surface.

[0062] (2) Tests on the water flux and protein anti-adsorption performance of the membranes in Examples 1-2 and Comparative Examples 1-6 were carried out.

[0063] Test process for protein anti-adsorption performance:

[0064] Bovine serum albumin (BSA) was used to study the adsorption performance of the polyethersulfone membrane to proteins, so as to characterize the anti-fouling performance of the polyethersulfone membrane.

[0065] ① Preparation of phosphate buffer solution Weigh 2.2 g of pure Na2HPO4, 0.2 g of NaH2PO4 and 8.5 g of NaCl respectively and add them into a 200 mL beaker. Dissolve them completely with deionized water, transfer the solution to a 1000 mL volumetric flask, rinse the beaker 5 times with deionized water and transfer the rinsing solution into the volumetric flask, then make up the volume to 1000 mL to obtain the phosphate buffer solution PBS with pH = 7.4.

[0066] ② Determination of BSA adsorption on polyethersulfone membrane

[0067] Use an ultraviolet spectrophotometer to investigate the adsorption of bovine serum albumin on the surface of the polyethersulfone membrane, and use this to characterize the anti-fouling performance of the polyethersulfone membrane. First, draw the A-ρ standard working curve (A is the absorbance, ρ is the BSA concentration) with the absorbance values A of bovine serum albumin at different concentrations at 298 nm. There is a good linear relationship within 0 - 10 g / L, and its linear regression equation is A = 0.04987ρ + 0.02972, and its correlation coefficient R 2 = 0.99431. Use the standard curve to calculate the adsorption amount per unit area of the polyethersulfone membrane in 0.1 g / L and 1.0 g / L BSA solutions.

[0068] Rinse the sample (the polyethersulfone membrane prepared in the example or comparative example) with absolute ethanol and deionized water respectively, and then rinse it with a buffer solution of PBS = 7.4 to remove the active groups and pollutants on the surface of the polyethersulfone membrane. Take the polyethersulfone membrane and soak it in the PBS buffer solution for 3 h first, then pour out the PBS solution, add 10 mL of 0.1 g or 1 g / L BSA solution respectively, and adsorb statically at a constant temperature of 30 °C for 5 h. After the adsorption reaches equilibrium, take out the sample and measure the absorbance value of the BSA solution at 280 nm to obtain the amount of BSA adsorbed per unit area.

[0069] Table 1 Performance test results

[0070]

[0071] As can be seen from Table 1, the polyethersulfone membranes prepared in Examples 1 - 2 have higher water flux and lower protein adsorption amount, indicating that the polysulfone membranes prepared by the present invention have good protein anti-adsorption performance. While in Comparative Examples 1 - 6, the necessary technical solutions of the present invention were not used, and there were obvious decreases in both water flux and protein anti-adsorption performance.

[0072] Therefore, the present invention adopts a polyethersulfone membrane with low protein adsorption function and its preparation method with the above structure. Through a carefully designed formula and preparation process, a polyethersulfone membrane with low protein adsorption function is successfully prepared. The addition of the amphiphilic copolymer P(PVP-r-PDMS) not only enhances the hydrophilicity and protein adsorption resistance of the membrane, but also realizes the optimization of the membrane structure through the fine regulation of the RTIPS method. Finally, a polyethersulfone hollow fiber membrane with excellent anti-fouling performance and high permeability is obtained, which has broad application prospects in the fields of hemodialysis, drug filtration, food industry, etc.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a polyethersulfone membrane with low protein adsorption function, characterized in that: It includes the following steps: (1) Weigh 862.5 g of dimethylacetamide and 67.5 g of polyethylene glycol with a molecular weight of 8000 Da into a reaction kettle respectively. Then add 270 g of polyethersulfone and 75 g of amphiphilic copolymer into the reaction kettle. After stirring at 80 °C for 4 h, cool down to 40 °C, add 225 g of dipropylene glycol into the casting solution, continue to stir for 6 h, and let it stand for defoaming to obtain a homogeneous casting solution; The preparation method of the amphiphilic copolymer is as follows: Dissolve 52.5 g of PVP and 26.3 g of PDMS in 120 g of butyl acetate. Add 1.2 g of initiator AIBN in a nitrogen environment, react for 12 h, precipitate the polymerization product with n-hexane, and dry it in an oven at 60 °C for 15 h to obtain the amphiphilic copolymer; (2) The homogeneous casting solution is extruded through a spinneret, passes through an air bath at a temperature of 50 °C and a humidity of 50%, enters a coagulation bath at 30 °C, and is solidified into a film by a water coagulation bath. The drawing speed is 10 m / s. Then, the prepared wet film is immersed in deionized water at a temperature of 30 °C for cleaning, and finally dried under the conditions of a temperature of 28 °C and a humidity of 60% to obtain a polyethersulfone filter membrane; the water flux of the polyethersulfone membrane is 2876 L / (m 2 ·h), and the protein adsorption amount is 28.8 μg / cm 2 ; The cross-section of the polyethersulfone membrane has a symmetric structure, and both the inner and outer surfaces are composed of dense sponge layers, and the pore size of the interpenetrating sponge structure in the middle is 0.2 μm.

2. A preparation method of a polyethersulfone membrane with low protein adsorption function, characterized in that: It includes the following steps: (1) Weigh 825 g of dimethylacetamide and 135 g of polyvinylpyrrolidone with a molecular weight of 38000 Da into a reaction kettle respectively. Then add 225 g of polyethersulfone and 150 g of amphiphilic copolymer into the reaction kettle. After stirring at 80 °C for 4 h, cool down to 35 °C, add 165 g of tetraethylene glycol into the casting solution, continue to stir for 6 h, and let it stand for defoaming to obtain a homogeneous casting solution; The preparation method of the amphiphilic copolymer is as follows: Dissolve 59 g of PVP and 39.4 g of PDMS in 100 g of butyl acetate. Add 1.6 g of initiator AIBN in a nitrogen environment, react for 12 h, precipitate the polymerization product with n-hexane, and dry it in an oven at 60 °C for 15 h to obtain the amphiphilic copolymer; (2)The homogeneous casting solution is extruded through a spinneret, passes through an air bath at a temperature of 35°C and a humidity of 80%, and then enters a coagulation bath at 35°C where it is solidified into a film by water coagulation bath. The drawing speed is 3 m / s. Then the prepared wet film is immersed in deionized water at a temperature of 40°C for cleaning, and finally dried under the conditions of a temperature of 28°C and a humidity of 60% to obtain a polyethersulfone filter membrane; the water flux of the polyethersulfone membrane is 3212 L / (m 2 ·h), and the protein adsorption amount is 25.3 μg / cm 2 .

Images