CN111892735A

CN111892735A - Preparation method and application of reaction separation integrated membrane of surface modification photocatalyst

Info

Publication number: CN111892735A
Application number: CN202010668110.0A
Authority: CN
Inventors: 李雪; 蔡韬; 黄娅; 李秀娟; 赵裕杰; 陈琛; 张禹弛
Original assignee: SUZHOU Institute OF WUHAN UNIVERSITY
Current assignee: SUZHOU Institute OF WUHAN UNIVERSITY
Priority date: 2020-07-13
Filing date: 2020-07-13
Publication date: 2020-11-06
Anticipated expiration: 2040-07-13
Also published as: CN111892735B

Abstract

The invention discloses a preparation method and application of a reaction separation integrated membrane of a surface modification photocatalyst, and belongs to the technical field of polymer material synthesis and separation. The method comprises the following steps: organic dyes EB, EY, RB and PB with photocatalysis are subjected to functional group conversion, amino functional groups are introduced, the organic dyes with the amino functional groups are directly modified on the surface of the membrane, or the organic dyes with the amino functional groups are copolymerized and then modified on the surface of the membrane, so that a reaction separation integrated membrane of the surface-modified photocatalyst is obtained, and the membrane can be used in the fields of chemical production, biomedicine, drug separation and the like. The organic dye used in the invention has high photocatalytic efficiency, lower price and lower toxicity, the modification method of the organic dye is simple, and the random copolymer is convenient to synthesize. The reaction separation integrated membrane can carry out polymerization reaction in aqueous solution at normal temperature, has mild reaction condition and little environmental pollution; the product is separated and purified within 18 hours.

Description

Preparation method and application of reaction separation integrated membrane of surface modification photocatalyst

Technical Field

The invention belongs to the technical field of polymer material synthesis and separation, and particularly relates to a preparation method and application of a reaction separation integrated membrane of a surface modification photocatalyst.

Technical Field

In recent years, the process of converting organic monomers into polymers by a photocatalytic technology is a hot issue in polymer material synthesis, is expected to be one of effective approaches to solving energy and environmental problems, and is receiving attention from more and more researchers. The reaction has the advantages of low energy consumption, mild reaction conditions, controllable components, time, space and sequence and the like, and has wide application prospect in the aspect of polymer material synthesis. However, the photocatalyst suitable for polymerization reaction is expensive, resulting in high synthesis cost; in addition, the conventional method for dialysis purification of the polymerization product is time-consuming and inefficient in separation. If the reaction catalysis and the membrane separation can be combined together, and the membrane is taken as a catalyst carrier to form a reaction and separation integrated system, the use efficiency of the photocatalyst can be further improved, the reaction process and the subsequent chemical unit operation can be combined, the reaction and separation steps are greatly simplified, the selective reaction conversion is promoted, and the pollution and the energy consumption are fundamentally reduced.

The catalyst is loaded on the separation membrane, the membrane is used as a reactor, and the mixed solution after reaction is separated, so that the reaction solvent can be removed, and the recovery efficiency of the catalyst is improved. The research that a chiral square amide catalyst is grafted on a polybenzimidazole nanofiltration membrane for asymmetric Michael addition reaction is reported in 2018, and more than 98% of products can be recovered after the reaction (Didastalou et al. ACS Cat.2018, 8,7430).

At present, reports about separating an integrated membrane for photocatalytic polymerization are limited to limited monomer single catalyst polymerization research (Zhao y.et al.j.mater.chem.a 2020,8,9825), the polymer structure is single, the application range is narrow, the polymerization rate still needs to be improved, the oxygen resistance is poor, and the complicated oxygen removal process consumes time and energy.

Disclosure of Invention

The invention aims to solve the problems of the existing polymer synthesis technology and provides a preparation method and application of a reaction separation integrated membrane of a surface modified photocatalyst.

The purpose of the invention is realized by the following technical scheme:

a preparation method of a reaction separation integrated membrane of a surface modification photocatalyst is a method A or a method B, wherein the method A comprises the following steps:

(1) the organic dye with photocatalysis is converted into functional group and introduced with amino functional group.

(2) Modifying organic dye with amino functional group on the surface of the membrane to obtain a reaction separation integrated membrane of the surface modified photocatalyst.

The method B comprises the following steps:

(1') converting the functional group of the organic dye having a photocatalytic action to introduce an amino functional group, as in the step (1) of the method A.

(2') copolymerizing an organic dye having an amino functional group to obtain a copolymer containing an organic dye component.

(3') modifying the copolymer containing the organic dye component to the surface of the membrane to obtain a reaction separation integrated membrane of the surface modified photocatalyst.

The organic dye with photocatalysis comprises tetraiodofluorescein B (EB), Eosin Y (EY), Rose Bengal (RB) and Phloxine B (PB), the structural formula of the organic dyes is shown in figure 1, and the structural formula after the amino functional group is introduced is shown in figure 2.

The membrane comprises an ultrafiltration membrane which takes polyimide, nylon, polyester, polyethersulfone, polysulfone, polyamide, polyacrylonitrile, polyvinylidene fluoride or cellulose acetate as raw materials.

The step (1) of the above method a comprises the steps of: dissolving an organic dye and 3-bromopropylamine hydrobromide in a solvent, reacting under heating, precipitating a reaction product in a precipitator to obtain a crude product, and repeatedly dissolving and precipitating the crude product for purification to obtain the organic dye with an introduced amino functional group. In the step, the feeding molar ratio of the organic dye to the 3-bromopropylamine hydrobromide is preferably 1: 1-1: 2; the solvent is preferably one or a mixed solvent of dimethyl sulfoxide and N, N-dimethylacetamide; the reaction condition is preferably 80-120 ℃ for 6-24 h; the precipitator is preferably a mixed solution of deionized water and diethyl ether in a volume ratio of 10: 1-1: 10.

Step (2') of the above method B is shown in fig. 3, and includes the following steps:

i: dissolving organic dye with amino functional groups, ethylene glycol diglycidyl ether or polyethylene glycol diglycidyl ether, N-dimethylethylenediamine and N-BOC-1, 4-diaminobutane in a solvent, reacting under heating, precipitating in a precipitator after the reaction is finished, and repeatedly dissolving and purifying the precipitate to obtain an intermediate product 1. Wherein the feeding molar ratio of the organic dye with amino functional groups to the ethylene glycol diglycidyl ether or the polyethylene glycol diglycidyl ether, the N, N-dimethylethylenediamine and the N-BOC-1, 4-diaminobutane is preferably 1:3:1: 1; the solvent is preferably one or a mixture of two or three of N, N-dimethylformamide, dimethyl sulfoxide and N, N-dimethylacetamide; the reaction condition is preferably 80-120 ℃ for 6-48 h; the precipitating agent is preferably diethyl ether or acetone.

ii: and (e) dissolving the intermediate product 1 obtained in the step (i) and 1, 3-propane sultone with equal molar ratio or excessive molar ratio in a solvent for reaction, precipitating the reaction product in a precipitator, and repeatedly dissolving and precipitating precipitates for purification to obtain an intermediate product 2. Wherein the feeding molar ratio of the intermediate product 1 to the 1, 3-propane sultone is preferably 1: 1-1: 10; the solvent is preferably one or a mixture of two or three of N, N-dimethylformamide, dimethyl sulfoxide and N, N-dimethylacetamide; the reaction condition is preferably 20-60 ℃ for 6-24 h; the precipitating agent is preferably diethyl ether or acetone.

iii: and (3) dissolving the intermediate product 2 obtained in the step ii and trifluoroacetic acid in a solvent for reaction, precipitating the reaction product in a precipitator to obtain a crude copolymer product, and repeatedly dissolving and precipitating the crude product for purification to obtain the copolymer containing the organic dye component. Wherein the feeding molar ratio of the intermediate product 2 to the trifluoroacetic acid is preferably 1: 1-1: 10; the solvent is preferably one or a mixture of two or three of N, N-dimethylformamide, dimethyl sulfoxide and N, N-dimethylacetamide; the reaction condition is preferably 20-60 ℃ for 6-24 h; the precipitating agent is preferably diethyl ether or acetone.

The method for modifying the surface of the membrane in the step (2) of the method A and the step (3') of the method B comprises the following steps:

a) dissolving dopamine hydrochloride in 0.005-0.05 mol L^-1、8.0<pH<And (3) preparing a solution A in a Tris buffer solution of 8.6, and immersing the ultrafiltration membrane into the solution A (8-12 hours) to fully coat the dopamine hydrochloride on the ultrafiltration membrane. Wherein the concentration of the dopamine hydrochloride in the solution A is preferably 100-500 mg/L.

b) Adding triethylamine into an organic dye aqueous solution with amino functional groups or a copolymer aqueous solution containing organic dye components to prepare a solution B, and then immersing the dopamine hydrochloride coating film obtained in the step a) into the solution B for 0.5-6 hours to obtain a reaction separation integrated film of the surface modified photocatalyst. Wherein, the concentration of the organic dye with amino functional groups or the copolymer containing organic dye components in the solution B is preferably 10-100 g/L, and the volume fraction of triethylamine in the solution B is preferably 0.2-0.7%.

A reaction separation integrated membrane of a surface modified photocatalyst is prepared by the method.

The reaction separation integrated membrane of the surface modification photocatalyst can be used in different fields, such as polymerization reaction and separation in chemical production, preparation and separation of sustained release agents of biological medicines, preparation and separation of medicines and medicine intermediates and the like.

The reaction separation integrated membrane of the surface modification photocatalyst can carry out polymerization reaction in aqueous solution at normal temperature, or in organic solvent under heating condition; the used catalyst is in ppm level, the reaction steps are simple, and the method is very suitable for the field of polymer material synthesis. Such as its application in polymer synthesis, comprising the steps of: soaking the reaction separation integrated membrane of the surface modified photocatalyst into a solution containing vinyl monomers, and irradiating with visible light (lambda)_max＝450～600nm) polymerizing the vinyl monomer into a polymer. The vinyl monomer comprises methacrylate, acrylate, methacrylamide, acrylamide and styrene.

The invention has the following advantages and beneficial effects:

(1) the organic dye used in the invention has high photocatalytic efficiency, lower price and lower toxicity, and the copolymerization reaction is convenient for introducing other functional groups capable of performing subsequent reaction and is easy to amplify.

(2) The organic dye used in the invention has simple modification method, convenient synthesis of random copolymer, mild condition and easy realization.

(3) The reaction separation integrated membrane of the surface modification photocatalyst prepared by the invention can carry out polymerization reaction in aqueous solution at normal temperature, has mild reaction conditions and little environmental pollution; the product is separated and purified within 18 hours.

Drawings

FIG. 1 is a structural formula diagram of an organic dye with a photocatalytic effect.

FIG. 2 is a structural diagram of an organic dye with a photocatalytic function after an amino functional group is introduced.

FIG. 3 shows an organic dye with amino functional groups (as EB-NH)₂For example), wherein n, x, y and z are natural numbers, n is not less than 2, and x: y: z is 1:1: 1.

FIG. 4 is a nuclear magnetic resonance hydrogen spectrum of a copolymerization product of aminopropyl tetraiodofluorescein B, polyethylene glycol diglycidyl ether, N-dimethylethylenediamine, and N-BOC-1, 4-diaminobutane.

FIG. 5 is an electron micrograph of a polyimide ultrafiltration-based membrane.

FIG. 6 is an electron micrograph of a polyimide film having a surface modified with tetraiodofluorescein B.

FIG. 7 is a graph showing the results of example 8. FIG. a is a graph showing the relation ln [ M ] between the apparent rate of N, N-dimethylacrylamide photocatalytic polymerization and visible light illumination time]₀/[M]_tT.t; the graph b is the corresponding relation between the apparent rate of N, N-dimethylacrylamide photocatalytic polymerization and visible light extinction; c is hydrogen nuclear magnetic spectrometry of the product of N, N-dimethylacrylamide photocatalytic polymerizationMolecular weight, molecular weight determined by gel chromatography and polydispersity index.

FIG. 8 is a graph showing the results of example 9. FIG. a shows the observation rate and the visible light illumination time of a product obtained by N, N-dimethylacrylamide photocatalytic polymerization under the condition of no oxygen removal or oxygen removal when the feeding ratio is 400: 1; and b is the molecular weight of the product of N, N-dimethylacrylamide photocatalytic polymerization under the condition of no oxygen removal, the molecular weight and the polydispersity coefficient of the gel chromatography.

FIG. 9 is a graph of the apparent rate of N, N-diethylacrylamide photocatalytic polymerization with visible light illumination time ln [ M ]]₀/[M]_tvs.t。

The specific implementation mode is as follows:

to facilitate understanding and practice of the invention by those of ordinary skill in the art, the following detailed description of the invention is provided in conjunction with the examples and the accompanying drawings, it being understood that the examples described herein are for purposes of illustration and explanation only and are not intended to be limiting.

Example 1

2.64g of tetraiodofluorescein B disodium salt (3mmol) and 985mg of 3-bromopropylamine hydrobromide (4.5mmol) are added into 15mL of dimethyl sulfoxide, reaction is carried out for 12h at 80 ℃, after the reaction is finished, the mixture is precipitated into 150mL of mixed solution of deionized water and diethyl ether (the volume ratio of the two solvents is 1:1), and the product is purified by repeatedly dissolving the mixture in the dimethyl sulfoxide and the mixed solution of the deionized water and the diethyl ether, so that 2.2g of aminopropyl tetraiodofluorescein B is obtained, wherein the yield is about 80%.

Example 2

2.08g of eosin Y disodium salt (3mmol) and 985mg of 3-bromopropylamine hydrobromide (4.5mmol) were added to 15mL of dimethyl sulfoxide and reacted at 80 ℃ for 12 hours, after completion of the reaction, the mixture was precipitated in 150mL of a mixed solution of deionized water and diethyl ether (volume ratio of two solvents: 1), and the product was purified by repeated dissolution in dimethyl sulfoxide and precipitation in a mixed solution of deionized water and diethyl ether to obtain 1.7g of aminopropyleosin Y with a yield of about 80%.

Example 3

3.05g of rose bengal disodium salt (3mmol) and 985mg of 3-bromopropylamine hydrobromide (4.5mmol) are added to 15mL of dimethyl sulfoxide, and the mixture is reacted at 80 ℃ for 24 hours, after the reaction is completed, the mixture is precipitated in 150mL of a mixed solution of deionized water and diethyl ether (the volume ratio of the two solvents is 1:1), and the product is purified by repeatedly dissolving the mixture in the dimethyl sulfoxide and the mixed solution of the deionized water and the diethyl ether, so that 2.7g of aminopropyl rose bengal is obtained, and the yield is about 85%.

Example 4

Adding 2.49g of fluorescein pink B disodium salt (3mmol) and 985mg of 3-bromopropylamine hydrobromide (4.5mmol) into 15mL of dimethyl sulfoxide, reacting for 24h at 80 ℃, precipitating the mixture in 150mL of mixed solution of deionized water and diethyl ether (the volume ratio of the two solvents is 1:1) after the reaction is finished, and repeatedly dissolving the mixture in the dimethyl sulfoxide and the precipitate in the mixed solution of the deionized water and the diethyl ether to purify the product, so that 2.2g of aminopropyl fluorescein pink B is obtained, wherein the yield is about 80%.

Example 5

383mg (1mmol) of aminopropyltetraiodofluorescein B prepared in example 1, 1.5g (3mmol) of polyethylene glycol diglycidyl ether, 109. mu.L (1mmol) of N, N-dimethylethylenediamine and 191. mu.L (1mmol) of N-BOC-1, 4-diaminobutane were dissolved in 15mL of N, N-dimethylformamide and reacted at 80 ℃ for 12 hours, after completion of the reaction, the mixture was precipitated in ether cooled in an ice-water bath and then the dissolution and precipitation were repeated twice to give 2g of intermediate 1.

0.67g of intermediate 1 and 0.61g of 1, 3-propanesultone were dissolved in 10mL of dimethyl sulfoxide at a feed molar ratio of about 1:2, reacted at room temperature for 6 hours, and the reaction mixture was precipitated in 100mL of diethyl ether, followed by repeated dissolution and precipitation twice to give 0.73g of intermediate 2.

0.71g of intermediate product 2 and 0.5mL of trifluoroacetic acid were dissolved in 10mL of dimethyl sulfoxide, the molar ratio of the materials was about 1:1, the reaction was carried out at room temperature for 12 hours, the mixture after the reaction was precipitated in 100mL of diethyl ether, and then the dissolution and precipitation were repeated twice to obtain 0.65g of a copolymer of tetraiodofluorescein B, polyethylene glycol diglycidyl ether, N-dimethylethylenediamine and N-BOC-1, 4-diaminobutane, the nuclear magnetic resonance hydrogen spectrum of which is shown in FIG. 4.

Example 6

Spinning a polyimide ultrafiltration membrane by a non-solvent induced phase separation method, firstly, carrying out vacuum drying on a polyimide raw material at 80 ℃ for 3h to remove water, preparing a solution containing 18 wt% of polyimide and 16 wt% of polyethylene glycol from the dried polyimide raw material by taking N-methylpyrrolidone as a solvent and polyethylene glycol 400 as a pore-forming agent, stirring for 24h, and removing bubbles; spreading the solution on a glass plate with a scraper having a gap of 300 μm at room temperature and 60% relative humidity in air to obtain sheet, soaking the glass plate in water for 10min, taking out purified water, and soaking for 10 hr to obtain polyimide ultrafiltration membrane with pure water flux of 1340L · m^-2·h^-1(test pressure 0.95bar) and its scanning electron micrograph is shown in FIG. 5.

Example 7

Dopamine solution was prepared by dissolving 100mg of dopamine hydrochloride in 1L of 0.01mol/L, pH ═ 8.0 Tris buffer. The polyimide ultrafiltration membrane prepared in example 6 was immersed in a dopamine solution for 12 hours, and the impregnated membrane was washed with deionized water 3 times to prepare a dopamine coating membrane.

The copolymer prepared in example 5 was prepared as a 20g/L aqueous solution, and triethylamine was added thereto so that the reaction solution contained 0.5% (v: v) triethylamine, followed by stirring. The dopamine coated film was immersed in the above aqueous solution for 12 h. And obtaining the ultrafiltration membrane with the surface modified with the tetraiodofluorescein B. The pure water flux of the resulting membrane was 320 liters per square meter per hour (test pressure 0.95bar), and the scanning electron micrograph thereof is shown in FIG. 6.

Example 8

5mL of purified water-soluble monomers, N-dimethylacrylamide and 2- (butylsulfanylthiocarbonylthio) propionic acid, were dissolved in 50mL of ultrapure water at molar ratios of 200:1, 400:1 and 800:1, respectively. The reaction solution was transferred to an ultrafiltration cup loaded with the membrane obtained in example 7, and bubbled with argon for about 20 minutes. The ultrafiltration cup was sealed and placed in a visible green light (9.6W, lambda)_max＝520nm，2.4mW/cm²) Under the irradiation of (3), a photocatalytic polymerization reaction is carried out. At regular intervals, 1mL of the reaction solution was taken out using a syringe, and subjected to NMR spectroscopy and gel chromatographyAnd (6) carrying out analysis.

The experimental result shows that in the photocatalytic polymerization process, the apparent rate is in a linear relation with the irradiation time of the visible light, and the apparent rate constant is a constant value and decreases along with the increase of the target polymerization degree (as shown in FIG. 7 a); photocatalytic polymerization can be controlled on and off by a light source (as shown in fig. 7 b); the molecular weight of the polymerized product is controllable, and the polydispersity coefficient is narrow (as shown in FIG. 7 c). After the reaction is finished, unreacted monomers, solvents and the like are directly filtered by an ultrafiltration cup, and a polymerization product with the purity of 90 percent is obtained within 15 hours under the condition of external pressure of 1 bar.

Example 9

5mL of purified water-soluble monomers, N-dimethylacrylamide (48.4mmol) and 28.8mg of 2- (butylsulfanylthiocarbonylthio) propionic acid (0.121mmol), were dissolved in 45mL of ultrapure water in a molar ratio of 400: 1. The reaction solution was transferred to an ultrafiltration cup loaded with the membrane obtained in example 7 without removing oxygen. The ultrafiltration cup was sealed and placed in a visible green light (9.6W, lambda)_max＝560nm，2.4mW/cm²) Under the irradiation of (3), a photocatalytic polymerization reaction is carried out. At regular intervals, 1mL of the reaction solution was taken out using a syringe and analyzed by NMR spectroscopy and gel chromatography.

The experimental result shows that in the absence of oxygen, the apparent rate and the visible light irradiation time in the photocatalytic polymerization process are in a linear relationship, and the apparent rate constant is a fixed value, is similar to the rate constant in the absence of oxygen and decreases with the increase of the target polymerization degree (as shown in FIG. 8 a); the molecular weight of the polymerized product is controllable, and the polydispersity coefficient is narrow (as shown in FIG. 8 b). That is, the oxygen scavenging conditions are similar in product properties to the non-oxygen scavenging conditions, indicating that the reaction is resistant to oxygen.

Example 10

The aminopropyleosin Y prepared in example 2 was prepared as a 20g/L aqueous solution, and triethylamine was added thereto so that the reaction solution contained 0.5% (v: v) triethylamine, and the mixture was stirred uniformly. The dopamine coating film obtained in example 7 was immersed in the above aqueous solution for 12 h. An ultrafiltration membrane of surface-modified eosin Y was obtained. The pure water flux of the resulting membrane was 285 per square meter per hour (test pressure 1 bar).

5mL of purified water-soluble monomers, N-diethylacrylamide (36.4mmol) and 21.6mg of 2- (butylsulfanylthiocarbonylthio) propionic acid (0.091mmol) were dissolved in 45mL of ultrapure water in a molar ratio of 400: 1. The reaction solution was transferred to an ultrafiltration cup loaded with the resulting membrane. The ultrafiltration cup was sealed directly and placed in yellow (9.6W, lambda) visible light_max＝560nm，2.4mW/cm²) Under the irradiation of (3), a photocatalytic polymerization reaction is carried out. And dissolving N, N-diethyl acrylamide and 2- (butylthio thiocarbonylthio) propionic acid in 45mL of ultrapure water according to the molar ratios of 200:1 and 800:1 respectively, and carrying out photocatalytic polymerization according to the steps.

The experimental results show that in the photocatalytic polymerization process, the apparent rate is in a linear relationship with the visible light irradiation time, and the apparent rate constant is a constant value and decreases with the increase of the target polymerization degree (as shown in fig. 9). After the reaction is finished, unreacted monomers, solvents and the like are directly filtered by an ultrafiltration cup, and a polymerization product with the purity of 90 percent is obtained within 18 hours under the condition of external pressure of 1 bar.

It should be understood that parts of the specification not set forth in detail are well within the prior art.

It should be understood that the above description of the preferred embodiments is given for clarity and not for any purpose of limitation, and that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A preparation method of a reaction separation integrated membrane of a surface modification photocatalyst is characterized in that: method a or method B, wherein method a comprises the steps of:

(1) converting functional groups of organic dyes with photocatalysis and introducing amino functional groups;

(2) modifying an organic dye with an amino functional group to the surface of the membrane;

the method B comprises the following steps:

(1') the same as in the step (1) of the method A;

(2') copolymerizing an organic dye having an amino functional group to obtain a copolymer containing an organic dye component;

(3') modifying the copolymer containing the organic dye component to the surface of the film;

the organic dye with photocatalysis comprises tetraiodofluorescein B, eosin Y, rose bengal and phloxine B;

2. The method of claim 1, wherein: step (1) of method a comprises the steps of: dissolving an organic dye and 3-bromopropylamine hydrobromide in a solvent, reacting under heating, precipitating a reaction product in a precipitator to obtain a crude product, and repeatedly dissolving and precipitating the crude product for purification to obtain the organic dye with an introduced amino functional group.

3. The method of claim 2, wherein: the feeding molar ratio of the organic dye to the 3-bromopropylamine hydrobromide is 1: 1-1: 2; the solvent is one or a mixed solvent of dimethyl sulfoxide and N, N-dimethylacetamide; the reaction condition is that the reaction is carried out for 6-24 hours at 80-120 ℃; the precipitator is a mixed solution composed of deionized water and diethyl ether according to a volume ratio of 10: 1-1: 10.

4. The method of claim 1, wherein: step (2') of method B comprises the steps of:

i: dissolving organic dye with amino functional groups, ethylene glycol diglycidyl ether or polyethylene glycol diglycidyl ether, N-dimethylethylenediamine and N-BOC-1, 4-diaminobutane in a solvent, reacting under heating, precipitating in a precipitator after the reaction is finished, and repeatedly dissolving and purifying the precipitate to obtain an intermediate product 1;

ii: i, dissolving the intermediate product 1 obtained in the step i and 1, 3-propane sultone with equal molar ratio or excessive molar ratio in a solvent for reaction, precipitating the reaction product in a precipitator, and repeatedly dissolving and precipitating precipitates for purification to obtain an intermediate product 2;

iii: and (3) dissolving the intermediate product 2 obtained in the step ii and trifluoroacetic acid in a solvent for reaction, precipitating the reaction product in a precipitator to obtain a crude copolymer product, and repeatedly dissolving and precipitating the crude product for purification to obtain the copolymer containing the organic dye component.

5. The method of claim 4, wherein:

in the step i, the feeding molar ratio of the organic dye with amino functional groups to ethylene glycol diglycidyl ether or polyethylene glycol diglycidyl ether, N-dimethylethylenediamine and N-BOC-1, 4-diaminobutane is 1:3:1: 1; the solvent is one or a mixture of two or three of N, N-dimethylformamide, dimethyl sulfoxide and N, N-dimethylacetamide; the reaction condition is that the reaction is carried out for 6-48 h at 80-120 ℃; the precipitator is diethyl ether or acetone;

in the step ii, the feeding molar ratio of the intermediate product 1 to the 1, 3-propane sultone is 1: 1-1: 10; the solvent is one or a mixture of two or three of N, N-dimethylformamide, dimethyl sulfoxide and N, N-dimethylacetamide; the reaction condition is that the reaction is carried out for 6-24 hours at the temperature of 20-60 ℃; the precipitator is diethyl ether or acetone;

in the step iii, the feeding molar ratio of the intermediate product 2 to trifluoroacetic acid is 1: 1-1: 10; the solvent is one or a mixture of two or three of N, N-dimethylformamide, dimethyl sulfoxide and N, N-dimethylacetamide; the reaction condition is that the reaction is carried out for 6-24 hours at the temperature of 20-60 ℃; the precipitator is diethyl ether or acetone.

6. The method of claim 1, wherein: the method for modifying the surface of the membrane in the step (2) of the method A and the step (3') of the method B comprises the following steps:

a) dissolving dopamine hydrochloride in 0.005-0.05 mol L^-1、8.0<pH<8.6, preparing a solution A in a Tris buffer solution, and immersing the ultrafiltration membrane into the solution A to fully coat the dopamine hydrochloride on the ultrafiltration membrane;

b) adding triethylamine into an organic dye aqueous solution with amino functional groups or a copolymer aqueous solution containing organic dye components to prepare a solution B, and then immersing the dopamine hydrochloride coating film obtained in the step a) into the solution B for 0.5-6 hours to obtain a reaction separation integrated film of the surface modified photocatalyst.

7. The method of claim 6, wherein: the concentration of the dopamine hydrochloride in the solution A in the step a) is 100-500 mg/L; the concentration of the organic dye with amino functional groups or the copolymer containing organic dye components in the solution B in the step B) is 10-100 g/L, and the volume fraction of triethylamine in the solution B is 0.2-0.7%.

8. A reaction separation integrated membrane of a surface-modified photocatalyst, characterized in that: obtained by the production method according to any one of claims 1 to 7.

9. The use of the reaction separation integrated membrane of the surface-modified photocatalyst of claim 8 in biomedical, chemical production, and pharmaceutical separations.

10. The use of the surface-modified photocatalyst in the reactive separation of an integral membrane in polymer synthesis as claimed in claim 8, wherein: the method comprises the following steps: soaking the reaction separation integrated membrane with the surface modified photocatalyst into a solution containing vinyl monomers, and polymerizing the vinyl monomers into a polymer by visible light illumination.