Preparation method of charge-reversible uniform pore membrane and separation application thereof

Abstract

This invention discloses a method for preparing a charge-reversible uniformly porous membrane and its separation application. The main steps include: immersing a block copolymer uniformly porous membrane in an ethanol solution containing a quaternizing reagent with boric acid functional groups and a catalyst; heating the membrane and then removing it; eluting the adsorbed quaternizing reagent with deionized water to obtain a uniformly porous membrane with a glucose-induced charge reversal effect. Its performance is as follows: when the membrane comes into contact with a glucose solution, the charge on the membrane reverses; when used for the separation or retention of biomolecules such as proteins, the introduction of glucose into the solution produces significantly opposite regulatory effects on the retention rates of biomolecules with different charges. This invention provides a method for regulating the surface charge and separation selectivity of a uniformly porous membrane using glucose molecules, offering a new regulatory means for the precise separation of biomolecules using uniformly porous membranes.

Description

Technical Field

[0001] This invention belongs to the field of membrane materials, and specifically relates to a method for preparing a charge-reversible uniformly porous membrane and its separation application. Background Technology

[0002] Charge reversal in materials refers to the phenomenon where the charge carried by a material reverses under external stimuli, a scientific topic of great research value. Many polyelectrolytes exhibit charge reversal properties, and phenomena such as pH-induced, light-induced, and molecular-responsive charge reversal have been studied. However, unlike these reversal response mechanisms, the charge reversal mediated by glucose has been rarely studied. Compared to other stimuli, glucose, as a common biological carbohydrate molecule, exhibits non-biotoxicity in its charge reversal process, demonstrates excellent targeting properties, and shows promising application prospects in drug delivery, release, and protein separation.

[0003] Phenylboronic acid groups are widely used in the design of diol (sugar)-responsive polymers due to their diol (sugar) responsiveness, and their related properties have been applied in biosensing, drug delivery, nucleotide adsorbents, and self-healing systems. Glucose is a commonly used bio-auxiliary agent for stabilizing the stereostructure of macromolecules such as proteins, effectively preventing the denaturation and inactivation of bioactive molecules such as proteins. By utilizing the functional groups of phenylboronic acid to construct novel block copolymer systems and prepare homogeneous porous membranes with surface charge reversal, this technology achieves charge regulation and selectivity enhancement of the separation membrane while simultaneously preventing the inactivation of bioactive molecules. This is a unique advantage that cannot be achieved by adjusting the electrical properties of separation membranes through pH or ionic strength. This technology provides a new method for regulating the precise separation characteristics of homogeneous porous membranes, possessing both scientific value and promising practical application prospects. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a method for preparing a charge-reversible homogeneous porous membrane and its separation application. The method involves immersing a block copolymer homogeneous porous membrane in an ethanol solution containing a quaternizing reagent with boric acid functional groups and a catalyst. After heating for a period of time, the membrane is removed and the remaining quaternizing reagent on the membrane surface is washed with deionized water to obtain a homogeneous porous membrane with glucose-responsive reversible surface charge. Its performance is as follows: after immersing the membrane in a glucose solution of a certain concentration for a period of time, the zeta potential on the membrane surface undergoes a significant reversal; when the membrane is used for retention, the addition of glucose to the test solution produces opposite regulatory effects on the retention values ​​of different charged biomolecules. This invention provides a novel method for regulating the surface charge of homogeneous porous membranes through glucose biomolecules, offering a novel and effective means for precise separation and control of homogeneous porous membranes.

[0005] This invention employs the following technical solution: a method for preparing a charge-reversed uniformly porous membrane and controlling its separation selectivity, the method comprising the following steps:

[0006] (1) The block copolymer uniform porous membrane was immersed in a solution containing a catalyst and a quaternizing agent with boric acid functional groups;

[0007] (2) The above solution is heated so that the pyridine group of the uniformly porous membrane reacts fully with the quaternary ammonium salt in the quaternizing agent at a specific position;

[0008] (3) The quaternizing reagent adsorbed on the membrane surface is cleaned with deionized water to obtain a quaternized uniform porous membrane.

[0009] Furthermore, the block copolymer homogeneous porous membrane is made from a copolymer composed of polystyrene blocks and another polar block, including: polystyrene-block-polytetravinylpyridine, polystyrene-block-polydivinylpyridine, polymethyl methacrylate-block-polytetravinylpyridine, polymethyl methacrylate-block-polydivinylpyridine, polymethyl methacrylate-block-polytetravinylpyridine, and polyethylene-block-polytetravinylpyridine.

[0010] Furthermore, the block copolymer asymmetric uniformly porous membrane possesses the following characteristics: the pore size of its surface pores is not less than 5 nm, the porosity is not less than 10%, and the pore density is not less than 10. 14 / m 2 The thickness of the support layer located below the surface porous layer is not less than 1 micrometer.

[0011] Furthermore, the quaternizing agent containing boric acid is one or more of 3-bromophenylboronic acid, 4-bromophenylboronic acid, 3-bromomethylphenylboronic acid, 3-bromo-4-fluorophenylboronic acid, 4-bromo-2-fluorophenylboronic acid, 3-iodophenylboronic acid, and 2-fluoro-5-iodophenylboronic acid, preferably 3-bromomethylphenylboronic acid, 4-bromo-2-fluorophenylboronic acid, and 2-fluoro-5-iodophenylboronic acid.

[0012] Furthermore, the concentration of the boric acid quaternizing agent is 0.02 g / L-0.3 g / L, preferably 0.02 g / L-0.15 g / L.

[0013] Further, the catalyst is one or more of potassium chloride, potassium acetate, potassium iodide, silver nitrate, and silver iodide. The catalyst concentration is 0.02 g / L to 0.05 g / L.

[0014] Furthermore, in step (2), the heating temperature is 15-80℃, preferably 20-60℃. The heating time is 12-48 hours, preferably 18-36 hours.

[0015] Furthermore, in step (3), deionized water with a pH range of 5.9 to 7.4 is used to wash away excess unreacted quaternization reagent. The washing method is immersion washing, and the washing time is 4-24 hours, preferably 6-12 hours.

[0016] An application of the charge-reversible uniformly porous membrane prepared by the method described above in the separation of bioactive molecules is as follows:

[0017] A certain concentration of glucose is added to the solution of bioactive macromolecules to be separated, and the feed liquid is filtered under pressure to separate the bioactive molecules through a quaternized homogeneous membrane.

[0018] Furthermore, the concentration of glucose in the solution is 0.05 mol / L-0.2 mol / L, and the bioactive molecules are proteins, peptides, monoclonal antibodies, and DNA.

[0019] Furthermore, the filtration methods include dead-end filtration and cross-flow filtration, with a transmembrane pressure difference of 0.05 MPa to 0.3 MPa.

[0020] The advantages of this invention compared to the prior art are as follows:

[0021] (1) This invention provides a universal method for selectively functionalizing glucose-driven surface charge reversal of membranes;

[0022] (2) This invention proposes a method for modifying the surface charge of a uniformly porous membrane to achieve the control of the membrane surface charge, which combines the characteristic that the pores of the uniformly porous membrane have specific reaction sites, so that the quaternization can be selectively reacted at specific locations.

[0023] (3) The method provided by the present invention is simple and easy to implement, with mild conditions, and does not damage the uniform pore structure on the surface of the uniform pore membrane;

[0024] (4) The stimulus source for achieving charge reversal in this invention is naturally occurring glucose, which is non-toxic and has good compatibility with the application scenarios of high-value drug molecules. No post-processing or removal is required after its addition.

[0025] (5) The glucose-driven uniform porous membrane surface charge reversal effect proposed in this invention can be used for the reverse selective separation of bioactive molecules such as proteins with different charges. Attached Figure Description

[0026] Figure 1 Scanning electron microscopy characterization of the surface of the uniformly porous membrane before and after quaternization modification;

[0027] Figure 2 Characterization results of surface Zeta potentials in response to different glucose concentrations after quaternization modification of uniformly porous membranes;

[0028] Figure 3X-ray photoelectron spectra of uniformly porous membranes before and after quaternization modification;

[0029] Figure 4 ATR-FTIR infrared spectroscopy characterization of the surface of the uniformly porous membrane before and after quaternization modification;

[0030] Figure 5 Statistical graph of the retention rates of proteins with different charges before and after the quaternization reaction of the uniformly porous membrane; Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, but the described embodiments do not constitute a limitation on the present invention.

[0032] Example 1

[0033] 1) Quaternization reaction of uniformly porous membrane: A uniformly porous membrane prepared from polystyrene-block-polytetravinylpyridine was selected and immersed in 50 mL of 0.05 g / L 4-bromophenylboronic acid ethanol solution, with 0.03 g / L potassium chloride dissolved as a catalyst. The membrane was thoroughly wetted, and then the solution was transferred to an oil bath at 50 °C and heated for approximately 24 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for approximately 8 hours to wash away any residual quaternizing reagent on the membrane surface. After the membrane was completely dried, the surface morphology was characterized using scanning electron microscopy (SEM). See Appendix. Figure 1 The resulting sample had a pore size of 13 ± 0.5 nm, a porosity of 13%, and a pore density of 2.0 × 10⁻⁶. 14 / m 2 A uniformly porous membrane.

[0034] 2) Characterization of charge reversal performance of uniformly porous membranes: The surface Zeta potential of the modified uniformly porous membranes was tested using potassium chloride solutions with glucose concentrations ranging from 0.05 mol / L to 0.2 mol / L as the eluent. The results are attached. Figure 2 As shown, this indicates that after modification, at the same pH, the membrane surface potential shifts significantly towards a negative potential with increasing glucose concentration. Furthermore, at physiological pH (pH = 7.2–7.4), the membrane surface potential changes from positive to negative after the addition of glucose to the eluent, exhibiting a clear charge reversal phenomenon. (See attached image.) Figure 3 These are X-ray photoelectron spectra before and after the quaternization reaction of the uniformly porous membrane. The shift in chemical bond binding energy after the nitrogen element peak separation reflects the successful conduction of the quaternization reaction. (Attached) Figure 4 These are ATR-FTIR infrared spectra of the surface of the uniformly porous membrane before and after the quaternization reaction, with the 1357-1363 cm⁻¹ region after the quaternization reaction. -1 The presence of a distinct absorption peak at 3372 cm⁻¹ confirms the successful introduction of the phenylboronic acid group. Furthermore, the peak at 3372 cm⁻¹ further confirms this. -1 The significant enhancement of the hydroxyl absorption peak further corroborates this point.

[0035] 3) Solute Retention Performance Test: The homogeneous membrane before and after modification was used to separate and retain protein solutions with different charges. Positively charged lysozyme and negatively charged hemoglobin were used as the separation targets. The protein concentration was 0.5 g / L. Glucose was added to the protein solution to prepare a protein solution with a glucose concentration of 0.1 mol / L. The retention rates are shown in the attached figure. Figure 5 As shown in the figure. The results indicate that the modified uniformly porous membrane exhibits opposite selective regulatory effects on protein molecules with different charges after glucose is added to the protein stock solution. Specifically, the retention rate of positively charged proteins decreases while the retention rate of negatively charged proteins increases, meaning that it produces opposite regulatory effects on the retention behavior of solutes with different charges.

[0036] Example 2

[0037] 1) A homogeneous porous membrane prepared from polymethyl methacrylate-block-polytetravinylpyridine was selected and immersed in 50 mL of 0.15 g / L 2-fluoro-5-iodophenylboronic acid ethanol solution, with 0.02 g / L silver nitrate dissolved as a catalyst. The membrane was thoroughly wetted. The solution was then transferred to a 50°C oil bath and heated for approximately 24 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for about 8 hours to remove residual quaternizing reagents from the membrane surface. After complete drying, the membrane surface morphology was characterized using scanning electron microscopy, yielding a pore size of 11 ± 0.3 nm, a porosity of 11%, and a pore density of 1.7 × 10⁻⁶. 14 / m 2 A uniformly porous membrane.

[0038] 2) The surface Zeta potential of the modified uniformly porous membrane was measured at different glucose concentrations. The results showed that a significant charge reversal phenomenon occurred on the membrane surface after the addition of glucose. XPS and ATR-FTIR infrared spectroscopy further verified the successful quaternization reaction.

[0039] 3) The retention performance of the modified uniform-porous membrane was tested. It was found that after adding a certain concentration of glucose to the peptide stock solution, the uniform-porous membrane exhibited opposite selective control effects on peptides with different charges. Specifically, the retention rate of positively charged peptides decreased, while the retention rate of negatively charged peptides increased. In other words, the modified uniform-porous membrane can produce opposite separation control effects on solute molecules with different charges.

[0040] Example 3

[0041] 1) A uniformly porous membrane prepared from polystyrene-block-polyvinylpyridine was selected and immersed in 50 mL of 0.10 g / L 3-iodophenylboronic acid ethanol solution, and 0.04 g / L silver nitrate was dissolved as a catalyst. The membrane was then fully wetted.

[0042] The solution was then transferred to a 75°C oil bath and heated for approximately 18 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for about 8 hours to remove residual quaternizing reagents from the membrane surface. After complete drying, the membrane surface morphology was characterized using scanning electron microscopy, revealing a pore size of 9 ± 0.2 nm, a porosity of 13%, and a pore density of 1.4 × 10⁻⁶.

[0043] 10 14 / m 2 A uniformly porous membrane.

[0044] 2) The surface Zeta potential of the modified uniformly porous membrane was measured at different glucose concentrations. The results showed that a significant charge reversal phenomenon occurred on the membrane surface after the addition of glucose. XPS and ATR-FTIR infrared spectroscopy further verified the successful quaternization reaction.

[0045] 3) The retention performance of the modified uniform-porous membrane was tested. It was found that after adding a certain concentration of glucose to the antibody stock solution, the uniform-porous membrane exhibited opposite selective control effects on antibodies with different charges. That is, the retention rate of positively charged antibodies decreased, while the retention rate of negatively charged antibodies increased. In other words, the modified uniform-porous membrane can produce opposite separation control effects on solute molecules with different charges.

[0046] Example 4

[0047] 1) A homogeneous porous membrane prepared from polymethyl methacrylate-block-polyvinylpyridine was immersed in 50 mL of 0.25 g / L 3-bromo-4-fluorophenylboronic acid ethanol solution, with 0.03 g / L silver nitrate dissolved as a catalyst. The membrane was thoroughly wetted. The solution was then transferred to an 80°C oil bath and heated for approximately 36 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for about 8 hours to remove residual quaternizing agents from the membrane surface. After complete drying, the membrane surface morphology was characterized using scanning electron microscopy, yielding a pore size of 8 ± 0.1 nm, a porosity of 12%, and a pore density of 1.4 × 10⁻⁶. 14 / m 2 A uniformly porous membrane.

[0048] 2) The surface Zeta potential of the modified uniformly porous membrane was measured at different glucose concentrations. The results showed that a significant charge reversal phenomenon occurred on the membrane surface after the addition of glucose. XPS and ATR-FTIR infrared spectroscopy further verified the successful quaternization reaction.

[0049] 3) The retention performance of the modified uniformly porous membrane was tested. It was found that after adding a certain concentration of glucose to the protein stock solution, the uniformly porous membrane exhibited opposite selective control effects on proteins with different charges. Specifically, the retention rate of positively charged proteins decreased, while the retention rate of negatively charged proteins increased. In other words, the modified uniformly porous membrane can produce opposite separation control effects on solute molecules with different charges.

[0050] Example 5

[0051] 1) A uniformly porous membrane prepared from polystyrene-block-polyvinylpyridine was selected and immersed in 50 mL of 0.15 g / L 4-bromophenylboronic acid ethanol solution, with 0.01 g / L silver nitrate dissolved as a catalyst. The membrane was thoroughly wetted. The solution was then transferred to an oil bath at 60 °C and heated for approximately 12 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for approximately 8 hours to remove residual quaternizing reagents from the membrane surface. After complete drying, the membrane surface morphology was characterized using scanning electron microscopy, yielding a pore size of 13 ± 0.3 nm, a porosity of 10%, and a pore density of 1.2 × 10⁻⁶. 14 / m 2 A uniformly porous membrane.

[0052] 2) The surface Zeta potential of the modified uniformly porous membrane was measured at different glucose concentrations. The results showed that a significant charge reversal phenomenon occurred on the membrane surface after the addition of glucose. XPS and ATR-FTIR infrared spectroscopy further verified the successful quaternization reaction.

[0053] 3) The retention performance of the modified uniform-porous membrane was tested. It was found that after adding a certain concentration of glucose to the peptide stock solution, the uniform-porous membrane exhibited opposite selective control effects on peptides with different charges. Specifically, the retention rate of positively charged peptides decreased, while the retention rate of negatively charged peptides increased. In other words, the modified uniform-porous membrane can produce opposite separation control effects on solute molecules with different charges.

[0054] Example 6

[0055] 1) A uniformly porous membrane prepared from polyethylene-block-polytetravinylpyridine was selected and immersed in 50 mL of 0.03 g / L 3-bromomethylphenylboronic acid ethanol solution, with 0.05 g / L silver nitrate dissolved as a catalyst. The membrane was thoroughly wetted. The solution was then transferred to an oil bath at 75°C and heated for approximately 30 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for about 8 hours to remove residual quaternizing reagents from the membrane surface. After complete drying, the membrane surface morphology was characterized using scanning electron microscopy, yielding a pore size of 13 ± 0.1 nm, a porosity of 12%, and a pore density of 1.5 × 10⁻⁶. 14 / m 2A uniformly porous membrane.

[0056] 2) The surface Zeta potential of the modified uniformly porous membrane was measured at different glucose concentrations. The results showed that a significant charge reversal phenomenon occurred on the membrane surface after the addition of glucose. XPS and ATR-FTIR infrared spectroscopy further verified the successful quaternization reaction.

[0057] 3) The retention performance of the modified uniform-porous membrane was tested. It was found that after adding a certain concentration of glucose to the antibody stock solution, the uniform-porous membrane exhibited opposite selective control effects on antibodies with different charges. That is, the retention rate of positively charged antibodies decreased, while the retention rate of negatively charged antibodies increased. In other words, the modified uniform-porous membrane can produce opposite separation control effects on solute molecules with different charges.

[0058] Example 7

[0059] 1) A homogeneous porous membrane prepared from polymethyl methacrylate-block-polytetravinylpyridine was selected and immersed in 50 mL of 0.02 g / L 2-fluoro-5-iodophenylboronic acid ethanol solution, with 0.01 g / L silver nitrate dissolved as a catalyst. The membrane was thoroughly wetted. The solution was then transferred to an 80°C oil bath and heated for approximately 36 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for approximately 8 hours to remove residual quaternizing reagents from the membrane surface. After complete drying, the membrane surface morphology was characterized using scanning electron microscopy, yielding a pore size of 10 ± 0.5 nm, a porosity of 13%, and a pore density of 1.1 × 10⁻⁶. 14 / m 2 A uniformly porous membrane.

[0060] 2) The surface Zeta potential of the modified uniformly porous membrane was measured at different glucose concentrations. The results showed that a significant charge reversal phenomenon occurred on the membrane surface after the addition of glucose. XPS and ATR-FTIR infrared spectroscopy further verified the successful quaternization reaction.

[0061] 3) The retention performance of the modified uniform-porous membrane was tested. It was found that after adding a certain concentration of glucose to the peptide stock solution, the uniform-porous membrane exhibited opposite selective control effects on peptides with different charges. Specifically, the retention rate of positively charged peptides decreased, while the retention rate of negatively charged peptides increased. In other words, the modified uniform-porous membrane can produce opposite separation control effects on solute molecules with different charges.

[0062] Example 8

[0063] 1) A uniformly porous membrane prepared from polystyrene-block-polytetravinylpyridine was selected and immersed in 50 mL of 0.03 g / L 4-bromo-2-fluorophenylboronic acid ethanol solution, with 0.03 g / L silver nitrate dissolved as a catalyst. The membrane was thoroughly wetted. The solution was then transferred to an oil bath at 65°C and heated for approximately 12 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for approximately 8 hours to remove residual quaternizing reagents from the membrane surface. After complete drying, the membrane surface morphology was characterized using scanning electron microscopy, yielding a pore size of 12 ± 0.1 nm, a porosity of 13%, and a pore density of 1.5 × 10⁻⁶. 14 / m 2 A uniformly porous membrane.

[0064] 2) The surface Zeta potential of the modified uniformly porous membrane was measured at different glucose concentrations. The results showed that a significant charge reversal phenomenon occurred on the membrane surface after the addition of glucose. XPS and ATR-FTIR infrared spectroscopy further verified the successful quaternization reaction.

[0065] 3) The retention performance of the modified uniformly porous membrane was tested. It was found that after adding a certain concentration of glucose to the protein stock solution, the uniformly porous membrane exhibited opposite selective control effects on proteins with different charges. Specifically, the retention rate of positively charged proteins decreased, while the retention rate of negatively charged proteins increased. In other words, the modified uniformly porous membrane can produce opposite separation control effects on solute molecules with different charges.

[0066] Example 9

[0067] 1) A uniformly porous membrane prepared from polystyrene-block-polytetravinylpyridine was selected and immersed in 50 mL of 0.03 g / L 3-bromophenylboronic acid ethanol solution, with 0.02 g / L potassium iodide dissolved as a catalyst. The membrane was thoroughly wetted. The solution was then transferred to an oil bath at 65°C and heated for approximately 12 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for approximately 8 hours to remove residual quaternizing reagents from the membrane surface. After complete drying, the membrane surface morphology was characterized using scanning electron microscopy, yielding a pore size of 11 ± 0.1 nm, a porosity of 12%, and a pore density of 1.3 × 10⁻⁶. 14 / m 2 A uniformly porous membrane.

[0068] 2) The surface Zeta potential of the modified uniformly porous membrane was measured at different glucose concentrations. The results showed that a significant charge reversal phenomenon occurred on the membrane surface after the addition of glucose. XPS and ATR-FTIR infrared spectroscopy further verified the successful quaternization reaction.

[0069] 3) The retention performance of the modified uniformly porous membrane was tested. It was found that after adding a certain concentration of glucose to the protein stock solution, the uniformly porous membrane exhibited opposite selective control effects on proteins with different charges. Specifically, the retention rate of positively charged proteins decreased, while the retention rate of negatively charged proteins increased. In other words, the modified uniformly porous membrane can produce opposite separation control effects on solute molecules with different charges.

[0070] Example 10

[0071] 1) A homogeneous porous membrane prepared from polystyrene-block-polytetravinylpyridine was selected and immersed in 50 mL of 0.3 g / L 4-bromophenylboronic acid ethanol solution, with 0.04 g / L silver iodide dissolved as a catalyst. The membrane was thoroughly wetted. The solution was then transferred to an oil bath at 15°C and heated for approximately 48 hours. Finally, the membrane was immersed in deionized water at pH 6.5 for approximately 8 hours to remove residual quaternizing reagents from the membrane surface. After complete drying, the membrane surface morphology was characterized using scanning electron microscopy, yielding a pore size of 12 ± 0.1 nm, a porosity of 13%, and a pore density of 1.5 × 10⁻⁶. 14 / m 2 A uniformly porous membrane.

[0072] 2) The surface Zeta potential of the modified uniformly porous membrane was measured at different glucose concentrations. The results showed that a significant charge reversal phenomenon occurred on the membrane surface after the addition of glucose. XPS and ATR-FTIR infrared spectroscopy further verified the successful quaternization reaction.

[0073] 3) The retention performance of the modified uniformly porous membrane was tested. It was found that after adding a certain concentration of glucose to the protein stock solution, the uniformly porous membrane exhibited opposite selective control effects on proteins with different charges. Specifically, the retention rate of positively charged proteins decreased, while the retention rate of negatively charged proteins increased. In other words, the modified uniformly porous membrane can produce opposite separation control effects on solute molecules with different charges.

[0074] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a charge-reversible uniformly porous membrane, characterized in that, The method includes the following steps: (1) The block copolymer uniformly porous membrane is immersed in a solution containing a catalyst and a quaternizing agent with boric acid functional groups; the block copolymer of the block copolymer uniformly porous membrane is prepared by a copolymer composed of polystyrene blocks and another polar block, including: polystyrene-block-polytetravinylpyridine, polystyrene-block-polydivinylpyridine, polymethyl acrylate-block-polytetravinylpyridine, polymethyl methacrylate-block-polydivinylpyridine, polymethyl methacrylate-block-polytetravinylpyridine, polyethylene-block-polytetravinylpyridine; the quaternizing agent with boric acid functional groups is one or more of 3-bromophenylboronic acid, 4-bromophenylboronic acid, 3-bromomethylphenylboronic acid, 3-bromo-4-fluorophenylboronic acid, 4-bromo-2-fluorophenylboronic acid, 3-iodophenylboronic acid, and 2-fluoro-5-iodophenylboronic acid; the catalyst is one or more of potassium chloride, potassium iodide, silver nitrate, and silver iodide; (2) Heating the above solution to allow the uniformly porous membrane to react fully with the quaternizing reagent; (3) The quaternizing reagent adsorbed on the membrane surface is cleaned with deionized water to obtain a uniformly porous membrane with reversible charge.

2. The method according to claim 1, characterized in that, The block copolymer membrane in step (1) has a pore size of not less than 5 nm, a porosity of not less than 10%, and a pore density of not less than 10. 14 / m 2 The thickness of the support layer located below the surface porous layer is not less than 1 micrometer.

3. The method according to claim 1, characterized in that, In step (1), the concentration of the quaternizing agent containing boric acid functional groups is 0.02 g / L-0.3 g / L.

4. The method according to claim 1, characterized in that, The catalyst concentration is 0.01 g / L-0.05 g / L.

5. The method according to claim 1, characterized in that, In step (2), the heating temperature is 15-80 ℃ and the heating time is 12-48 hours.

6. The method according to claim 1, characterized in that, In step (3), deionized water with a pH range of 5.9 to 7.4 is used to clean the unreacted quaternization reagent. The cleaning method is immersion cleaning, and the cleaning time is 6-12 hours.

7. The application of a charge-reversible uniformly porous membrane prepared by the method according to any one of claims 1-6 in the separation of bioactive molecules, characterized in that, Specifically: A certain concentration of glucose is added to the solution of bioactive macromolecules to be separated, and the feed liquid is filtered under pressure to separate the bioactive molecules through a quaternized homogeneous membrane.

8. The application according to claim 7, characterized in that, The concentration of glucose in the solution of the biomolecules to be separated is 0.05 mol / L-0.2 mol / L, and the bioactive molecules are proteins, peptides, monoclonal antibodies and DNA.

9. The application according to claim 7, characterized in that, Pressure filtration methods include dead-end filtration and cross-flow filtration, with a transmembrane pressure difference of 0.05 MPa to 0.3 MPa.

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