阅读说明：本技术 一种改性聚乙烯亚胺聚合物及其制备方法 (Modified polyethyleneimine polymer and preparation method thereof ) 是由 张震 李准轩 罗文艺 王莹 朱淋淋 于 2020-12-26 设计创作，主要内容包括：本申请属于聚乙烯亚胺改性共聚物合成技术领域。本申请提供一种改性聚乙烯亚胺聚合物及其制备方法。改性聚乙烯亚胺聚合物包括作为主链的支化聚乙烯亚胺以及接枝在支化聚乙烯亚胺上的磺酰仲胺或聚磺酰胺,为浅黄色非粘稠固体。通过调整支化聚乙烯亚胺和N-磺酰基氮丙啶的反应摩尔比例,可选择性制备双亲性和油溶性的改性聚乙烯亚胺聚合物。油溶性聚合物表现出优异的荧光性能,双亲性聚合物在吸附材料、分析检测等领域具有较大的应用前景。本申请的制备方法无需真空反应环境或惰性气体氛围,仅在无溶剂、无催化剂的熔融环境中进行开环反应或开环聚合反应,合成条件温和,收率高,产物纯度高,有利于大规模的工业生产。(The application belongs to the technical field of synthesis of polyethyleneimine modified copolymers. The application provides a modified polyethyleneimine polymer and a preparation method thereof. The modified polyethyleneimine polymer comprises branched polyethyleneimine serving as a main chain and secondary sulfonylamine or polysulfonamide grafted on the branched polyethyleneimine, and is a light yellow non-viscous solid. By adjusting the reaction molar ratio of the branched polyethyleneimine to the N-sulfonyl aziridine, the amphiphilic and oil-soluble modified polyethyleneimine polymer can be selectively prepared. The oil-soluble polymer shows excellent fluorescence performance, and the amphiphilic polymer has a wide application prospect in the fields of adsorption materials, analysis and detection and the like. The preparation method does not need a vacuum reaction environment or an inert gas atmosphere, only carries out ring-opening reaction or ring-opening polymerization reaction in a melting environment without solvent or catalyst, has mild synthesis conditions, high yield and high product purity, and is beneficial to large-scale industrial production.)

1. A modified polyethyleneimine polymer is characterized by having a structure shown in formula (I);

wherein m and n are positive integers, m + n is more than or equal to 10 and less than or equal to 600, R₁Is an aziridine compound after ring opening, R₃Is R₁Or H, a, b and c are positive integers, a is more than or equal to 0 and less than or equal to 2, b is more than or equal to 0 and less than or equal to 2, c is more than or equal to 0 and less than or equal to 2, and R₃When H is contained, a, b and c are not 0 at the same time.

2. The modified polyethyleneimine polymer according to claim 1, wherein R is₁Has a structure shown in a formula (II);

wherein x is an integer greater than 0, R is H, alkyl or aryl, R is₂Is p-toluenesulfonyl, methanesulfonyl or pyridinesulfonyl;

when x is 1, the modified polyethyleneimine polymer is an amphiphilic polymer; when x is more than 1, the modified polyethyleneimine polymer is an oil-soluble polymer.

3. The modified polyethyleneimine polymer according to claim 2, wherein R is H, an alkyl group having 1 to 15 carbon atoms, or a salt thereof,

4. The modified polyethyleneimine polymer according to claim 1, wherein the modified polyethyleneimine polymer has a weight average molecular weight of greater than 4500.

5. A preparation method of a modified polyethyleneimine polymer is characterized in that an N-sulfonyl aziridine compound and branched polyethyleneimine are mixed and subjected to a melt reaction to prepare the modified polyethyleneimine polymer.

6. The method according to claim 5, wherein the N-sulfonyl aziridine compound has a structure represented by formula (III);

wherein R is H, an alkyl group having 1 to 15 carbon atoms,R₂Is p-toluenesulfonyl, methanesulfonyl or pyridinesulfonyl.

7. The method of claim 5, wherein the branched polyethyleneimine has a structure represented by formula (IV);

wherein m and n are positive integers, and m + n is more than or equal to 10 and less than or equal to 600.

8. The preparation method according to claim 5, wherein the branched polyethyleneimine has a weight average molecular weight of 600 to 25000.

9. The method of claim 5, wherein the molar ratio of the branched polyethyleneimine to the N-sulfonyl aziridine compound is from 1: (0.1-10).

10. The method according to claim 5, wherein the temperature of the melt reaction is 120 to 200 ℃ and the time is 30 to 90 min.

Technical Field

The application belongs to the technical field of polyethyleneimine modified copolymers, and particularly relates to a modified polyethyleneimine polymer and a preparation method thereof.

Background

Polyethyleneimine is a water-soluble graft polymer, and the molecular chain of polyethyleneimine has a large number of amine groups, and the most prominent characteristic is high cationic charge density. Structurally, polyethyleneimines can be classified into linear polyethyleneimines (L-PEI) and branched polyethyleneimines (B-PEI), in which amines on a molecular chain of the linear polyethyleneimines are all secondary amines, and amines on a molecular chain of the branched polyethyleneimines are primary amines, secondary amines, and tertiary amines. At present, polyethyleneimine has wide application in the fields of gene transfection, papermaking, flocculating agents, dye fixing agents, fiber modification and the like. In recent years, polyethyleneimine has received much attention as a novel metal ion-coordinating adsorbent due to its excellent adsorption performance. However, polyethyleneimine is a water-soluble viscous liquid, exists in a free molecular state in an aqueous phase, and has the disadvantages of difficult operation, difficult separation and recovery, easy loss and the like when used as an adsorbent.

The chemical modification of polyethyleneimine can greatly improve the performance and application range of polyethyleneimine. Currently, the grafting method of polyethyleneimine is to perform post-modification by using primary amine amino and secondary amine amino on polyethyleneimine, and common methods include coupling reaction with carboxylic acid, nucleophilic substitution reaction, ring opening reaction, michael addition reaction, and the like, and reaction with end-functionalized polymer or graft polymerization reaction. However, the separation and purification operations of the modified polyethyleneimine polymer are complicated, and methods such as dialysis and freeze drying are generally required to remove excessive unreacted reagents, byproducts, solvents and water, which is not suitable for large-scale production and application of products.

N-sulfonyl aziridine (aziridine) compounds are a very important class of tertiary heterocyclic compounds because they are the cornerstones of building complex nitrogen-containing compounds and are also important functional group transformation centers. The ring-opening reaction of the N-sulfonyl aziridine compound generally requires nucleophilic ring-opening under basic conditions or Lewis acid-catalyzed ring-opening of transition metals and the like. The sulfonyl activated secondary amine is used as an initiator, hexamethyldisilazane is used as a base, and N-sulfonyl aziridine can undergo ring-opening polymerization to synthesize narrow-distribution polysulfonamide macromolecules. However, these ring-opening polymerization reactions of N-sulfonylaziridine require the use of water and oxygen-free conditions, and require the use of expensive initiators, which are relatively severe.

Disclosure of Invention

In view of this, the present application provides a modified polyethyleneimine polymer and a preparation method thereof, and the preparation conditions are mild, the yield is high, a reaction solvent is not required, a separation and purification operation is not required, and the modified polyethyleneimine polymer for metal ion adsorption can be obtained.

The specific technical scheme of the application is as follows:

the application provides a modified polyethyleneimine polymer which has a structure shown in a formula (I);

wherein m and n are positive integers, m + n is more than or equal to 10 and less than or equal to 600, R₁Is an aziridine compound after ring opening, R₃Is R₁Or H, a, b and c are positive integers, a is more than or equal to 0 and less than or equal to 2, b is more than or equal to 0 and less than or equal to 2, c is more than or equal to 0 and less than or equal to 2, and R₃When H is contained, a, b and c are not 0 at the same time.

In the present application, the modified polyethyleneimine polymer is a light yellow non-viscous solid, and post-processing is easier to achieve than commercial polyethyleneimine. The amphiphilic polymer or the oil-soluble polymer can be selectively prepared, wherein the amphiphilic polymer has high adsorption efficiency for metal ion adsorption, the adsorption efficiency is basically unchanged during recycling, and the amphiphilic polymer has a wide application prospect in the fields of adsorption materials, analysis and detection and the like; the oil-soluble polymer exhibits excellent fluorescent properties.

Preferably, R₁Has a structure shown in a formula (II);

wherein x is an integer greater than 0, R is H, alkyl or aryl, R is₂Is p-toluenesulfonyl, methanesulfonyl or pyridinesulfonyl;

when x is 1, the modified polyethyleneimine polymer is an amphiphilic polymer; when x is more than 1, the modified polyethyleneimine polymer is an oil-soluble polymer.

In this application, R₂As an electron-withdrawing substituent, the electron cloud density on aziridine is reduced, so that nucleophilic ring-opening reaction can be easily carried out between the aziridine and primary amine and secondary amine of polyethyleneimine, and the yield of the product can be improved without strictly controlling the reaction conditions. When the equivalent of the N-sulfonyl aziridine is lower, the polyethyleneimine initiates the N-sulfonyl aziridine to carry out nucleophilic ring-opening reaction, and x in the formula (II) is 1, so that the amphiphilic polymer is obtained. When the equivalent weight of the N-sulfonyl aziridine is increased, the tertiary amine in the polyethyleneimine is used as an organic base, the primary amine and the secondary amine are used as initiation sites to initiate the anionic ring-opening polymerization of the N-sulfonyl aziridine, the chain length of the polyethyleneimine can be increased, and x in the formula (II) is an integer greater than 1, so that the oil-soluble polymer is obtained.

Preferably, R is H, an alkyl group having 1 to 15 carbon atoms,

In the present application, the selection of these substituents increases the molecular weight of the hydrophobic chain, which in turn facilitates the improvement of the properties of the polyethyleneimine polymer.

Preferably, the modified polyethyleneimine polymer has a weight average molecular weight of greater than 4500.

The application also provides a preparation method of the modified polyethyleneimine polymer, wherein the modified polyethyleneimine polymer is prepared by mixing the N-sulfonyl aziridine compound and the branched polyethyleneimine and performing a melt reaction.

In the application, primary amine and secondary amine sites of branched polyethyleneimine are utilized to initiate an N-sulfonyl aziridine compound to carry out ring opening synthesis on the modified polyethyleneimine, and a branched polyethyleneimine has three groups of primary, secondary and tertiary amino groups on a molecular chain, so that the branched polyethyleneimine is alkaline and cationic in activity, and is easier to react with an electrophilic reagent or react with an amino compound for modification. The preparation method disclosed by the application does not need a vacuum reaction environment or an inert gas atmosphere, only carries out ring-opening polymerization reaction in a melting environment without a solvent or a catalyst, is mild in synthesis conditions, free of environmental pollution in reaction, free of byproducts, high in N-sulfonyl aziridine conversion rate (> 99%), high in modified polyethyleneimine polymer yield (> 99%), high in purity (> 98%), free of separation and purification, and beneficial to large-scale industrial production.

Preferably, the N-sulfonyl aziridine compound has a structure represented by formula (III);

wherein R is H, an alkyl group having 1 to 15 carbon atoms,R₂Is tosyl, mesyl or pyridylsulfonyl.

Preferably, the branched polyethyleneimine has a structure shown in a formula (IV);

wherein m and n are positive integers, and m + n is more than or equal to 10 and less than or equal to 600.

Preferably, the weight average molecular weight of the branched polyethyleneimine is 600-25000.

Preferably, the molar ratio of the branched polyethyleneimine to the N-sulfonyl aziridine compound is 1: (0.1-10).

In the present application, the molar ratio is 1: (0.1-1), carrying out melt reaction to obtain an amphiphilic modified polymer; while continuing to increase the amount of the N-sulfonyl aziridine compound, the melt reaction produces an oil-soluble modified polymer.

Preferably, the temperature of the melting reaction is 120-200 ℃, and the time is 30-90 min.

In summary, the present application provides a modified polyethyleneimine polymer and a preparation method thereof. The modified polyethyleneimine polymer comprises branched polyethyleneimine as a main chain and secondary sulfonylamine or polysulfonamide grafted on the branched polyethyleneimine, is a light yellow non-viscous solid, and is easier to realize post-processing compared with commercial polyethyleneimine. By adjusting the reaction molar ratio of the branched polyethyleneimine to the N-sulfonyl aziridine, the amphiphilic and oil-soluble modified polyethyleneimine polymer can be selectively prepared. The oil-soluble polymer shows excellent fluorescence performance, the amphiphilic polymer has high adsorption efficiency for metal ion adsorption, the adsorption efficiency is basically unchanged during recycling, and the amphiphilic polymer has a wide application prospect in the fields of adsorption materials, analysis and detection and the like. The preparation method disclosed by the application does not need a vacuum reaction environment or an inert gas atmosphere, only carries out ring-opening reaction or ring-opening polymerization reaction in a melting environment without a solvent or a catalyst, is mild in synthesis conditions, does not need separation and purification operations such as dialysis and drying, is high in yield and product purity, and is beneficial to large-scale industrial production.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.

FIG. 1 shows the NMR spectra of the polyethyleneimine used in example 4 of the present application (top) and the product obtained (bottom);

FIG. 2 shows the NMR spectra of the polyethyleneimine used in example 5 of the present application (top) and the product obtained (bottom);

FIG. 3 is a chart of the infrared spectra of polyethyleneimine (A) used in example 4 of the present application, product (B) obtained, and product (C) obtained in example 7;

FIG. 4 is a gel chromatogram of the product obtained in example 5 of the present application;

FIG. 5 shows fluorescence spectra of the products obtained in examples 2 and 7 of the present application and branched polyethyleneimine having a molecular weight of 1800.

Detailed Description

In order to make the objects, features and advantages of the present application more obvious and understandable, the technical solutions in the embodiments of the present application are clearly and completely described, and it is obvious that the embodiments described below are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The branched polyethylenimines used in the examples of this application are commercially available and the N-sulfonyl aziridines in the examples of this application are prepared by reacting the corresponding aziridine with a sulfonyl chloride reagent. In the examples of the present application, the molar ratio of the branched polyethyleneimine to the aziridine compound, calculated with respect to the recurring units of the polyethyleneimine, is such that R of the aziridine compound is methyl and R is₂Is p-toluenesulfonyl.

Example 1

Weighing branched polyethyleneimine (molecular weight is 1800) and N-sulfonyl aziridine compound in a molar mass ratio of 1:0.3, adding the branched polyethyleneimine and the N-sulfonyl aziridine compound into a 10ml reagent bottle, placing the reagent bottle into the reagent bottle and stirring the reagent bottle for 30 seconds after the temperature of an oil bath pot or a heating plate or a heating sleeve reaches 200 ℃, so that the N-sulfonyl aziridine compound and the branched polyethyleneimine are uniformly mixed, maintaining the temperature at 200 ℃, and standing and reacting for 0.5h under normal pressure to obtain the modified polyethyleneimine polymer. The prepared product is characterized by being a polyethyleneimine modified copolymer subjected to nucleophilic ring opening of N-sulfonyl aziridine through nuclear magnetic resonance, the conversion rate reaches 100%, the purity is more than 98%, and complicated purification operations such as dialysis and drying are not needed.

Example 2

Weighing branched polyethyleneimine (molecular weight is 1800) and N-sulfonyl aziridine compound in a molar mass ratio of 1:0.5, adding the branched polyethyleneimine and the N-sulfonyl aziridine compound into a 10ml reagent bottle, placing the reagent bottle into the reagent bottle and stirring the reagent bottle for 30 seconds after the temperature of an oil bath pot or a heating plate or a heating sleeve reaches 200 ℃, so that the N-sulfonyl aziridine compound and the branched polyethyleneimine are uniformly mixed, maintaining the temperature at 200 ℃, and standing and reacting for 0.5h under normal pressure to obtain the modified polyethyleneimine polymer. The prepared product is characterized by being a polyethyleneimine modified copolymer subjected to nucleophilic ring opening of N-sulfonyl aziridine through nuclear magnetic resonance, the conversion rate reaches 100%, the purity is more than 98%, and complicated purification operations such as dialysis and drying are not needed.

Example 3

Weighing branched polyethyleneimine (molecular weight is 10000) and N-sulfonyl aziridine compound with the molar mass ratio of 1:0.3, adding the branched polyethyleneimine and the N-sulfonyl aziridine compound into a 10ml reagent bottle, placing the reagent bottle into the reagent bottle and stirring the reagent bottle for 30 seconds after the temperature of an oil bath pot or a heating plate or a heating sleeve reaches 200 ℃, so that the N-sulfonyl aziridine compound and the branched polyethyleneimine are uniformly mixed, maintaining the temperature at 200 ℃, and standing and reacting for 0.5h under normal pressure to obtain the modified polyethyleneimine polymer. The prepared product is characterized by being a polyethyleneimine modified copolymer subjected to nucleophilic ring opening of N-sulfonyl aziridine through nuclear magnetic resonance, the conversion rate reaches 100%, the purity is more than 98%, and complicated purification operations such as dialysis and drying are not needed.

Example 4

Weighing branched polyethyleneimine (molecular weight is 10000) and N-sulfonyl aziridine compound with the molar mass ratio of 1:0.5, adding the branched polyethyleneimine and the N-sulfonyl aziridine compound into a 10ml reagent bottle, placing the reagent bottle into the reagent bottle and stirring the reagent bottle for 30 seconds after the temperature of an oil bath pot or a heating plate or a heating sleeve reaches 200 ℃, so that the N-sulfonyl aziridine compound and the branched polyethyleneimine are uniformly mixed, maintaining the temperature at 200 ℃, and standing and reacting for 0.5h under normal pressure to obtain the modified polyethyleneimine polymer. The nuclear magnetic resonance hydrogen spectrograms of the polyethyleneimine (upper) and the prepared product (lower) used in the embodiment of the application are shown in fig. 1, and the infrared spectrograms of the polyethyleneimine (A) and the prepared product (B) are shown in fig. 3, which shows that the prepared product is the polyethyleneimine modified copolymer after nucleophilic ring opening of N-sulfonyl propane, the conversion rate reaches 100%, the purity is more than 98%, and complicated purification operations such as dialysis, drying and the like are not needed.

Example 5

Weighing branched polyethyleneimine (molecular weight is 10000) and an N-sulfonyl aziridine compound in a molar mass ratio of 1:1, adding the branched polyethyleneimine and the N-sulfonyl aziridine compound into a 10ml reagent bottle, placing the reagent bottle into the reagent bottle and stirring the reagent bottle for 30 seconds after the temperature of an oil bath pot or a heating plate or a heating sleeve reaches 200 ℃, so that the N-sulfonyl aziridine compound and the branched polyethyleneimine are uniformly mixed, maintaining the temperature at 200 ℃, and standing and reacting for 0.5h under normal pressure to obtain the modified polyethyleneimine polymer. The nuclear magnetic resonance hydrogen spectrograms of the polyethyleneimine (upper) and the prepared product (lower) used in the embodiment of the application are shown in fig. 2, and the gel chromatogram of the prepared product is shown in fig. 4, which indicates that the prepared product is the polyethyleneimine modified copolymer after nucleophilic ring opening of N-sulfonyl aziridine, the conversion rate reaches 100%, the purity is more than 98%, and complicated purification operations such as dialysis, drying and the like are not needed.

Example 6

Weighing branched polyethyleneimine (molecular weight is 600) and N-sulfonyl aziridine compound in a molar mass ratio of 1:5, adding the branched polyethyleneimine and the N-sulfonyl aziridine compound into a 10ml reagent bottle, placing the reagent bottle into the reagent bottle and stirring the reagent bottle for 30 seconds after the temperature of an oil bath pot or a heating plate or a heating sleeve reaches 200 ℃, so that the N-sulfonyl aziridine compound and the branched polyethyleneimine are uniformly mixed, maintaining the temperature of 200 ℃, and standing and reacting for 1.5 hours under normal pressure to obtain the modified polyethyleneimine polymer. The prepared product is characterized by being a polyethyleneimine modified copolymer obtained after ring-opening polymerization of N-sulfonyl propylidine anions through nuclear magnetic resonance, the conversion rate reaches 100%, the purity is more than 98%, and complicated purification operations such as dialysis and drying are not needed.

Example 7

The preparation method comprises the steps of weighing branched polyethyleneimine (molecular weight is 600) and N-sulfonyl aziridine compound with a molar mass ratio of 1:10, adding the branched polyethyleneimine and the N-sulfonyl aziridine compound into a 10ml reagent bottle, placing the reagent bottle into the reagent bottle after the temperature of an oil bath pot or a heating plate or a heating sleeve reaches 200 ℃, stirring for 30 seconds to uniformly mix the N-sulfonyl aziridine compound and the branched polyethyleneimine, maintaining the temperature at 200 ℃, and standing for reaction for 1.5 hours under normal pressure to obtain the modified polyethyleneimine polymer. The infrared spectrogram of the product (C) prepared in the embodiment of the application is shown in fig. 3, which shows that the prepared product is a polyethyleneimine modified copolymer obtained by ring-opening polymerization of N-sulfonyl aziridine anions, the conversion rate reaches 100%, the purity is more than 98%, and complicated purification operations such as dialysis and drying are not needed.

Example 8

The preparation method comprises the steps of weighing branched polyethyleneimine (molecular weight is 1800) and N-sulfonyl aziridine compound with the molar mass ratio of 1:5, adding the branched polyethyleneimine and the N-sulfonyl aziridine compound into a 10ml reagent bottle, placing the reagent bottle into the reagent bottle after the temperature of an oil bath pot or a heating plate or a heating sleeve reaches 200 ℃, stirring for 30 seconds to uniformly mix the N-sulfonyl aziridine compound and the branched polyethyleneimine, maintaining the temperature at 200 ℃, and standing for reaction for 1.5 hours under normal pressure to obtain the modified polyethyleneimine polymer. The prepared product is characterized by being a polyethyleneimine modified copolymer obtained after ring-opening polymerization of N-sulfonyl aziridine anions through nuclear magnetic resonance, the conversion rate reaches 100%, the purity is more than 98%, and complicated purification operations such as dialysis and drying are not needed.

Example 9

Weighing branched polyethyleneimine (molecular weight is 1800) and N-sulfonyl aziridine compound in a molar mass ratio of 1:7, adding the branched polyethyleneimine and the N-sulfonyl aziridine compound into a 10ml reagent bottle, placing the reagent bottle into the reagent bottle and stirring the reagent bottle for 30 seconds after the temperature of an oil bath pot or a heating plate or a heating sleeve reaches 200 ℃, so that the N-sulfonyl aziridine compound and the branched polyethyleneimine are uniformly mixed, maintaining the temperature of 200 ℃ and standing for reaction for 1.5 hours under normal pressure, and obtaining the modified polyethyleneimine polymer. The prepared product is characterized by being a polyethyleneimine modified copolymer obtained after ring-opening polymerization of N-sulfonyl aziridine anions through nuclear magnetic resonance, the conversion rate reaches 100%, the purity is more than 98%, and complicated purification operations such as dialysis and drying are not needed.

The characterization patterns of the products prepared in comparative examples 1-5 and examples 6-9 show that the nucleophilic ring-opening or anionic ring-opening polymerization of N-sulfonyl aziridine depends on the ratio of the N-sulfonyl aziridine to the amino groups in the branched polyethyleneimine. When the amino content of the branched polyethyleneimine is much greater than that of N-sulfonyl aziridine (examples 1-4), the N-sulfonyl aziridine undergoes a nucleophilic ring-opening reaction with the primary and secondary amines of the branched polyethyleneimine, i.e., one aziridine component is grafted per mole equivalent of amino groups; when the proportion of polyethyleneimine amino groups is less than that of sulfonyl aziridines (examples 6 to 9), the tertiary amine, as an organic base, continues to catalyze the anionic ring-opening polymerization of N-sulfonyl aziridines, i.e., grafting of polymerized components from a plurality of aziridines onto each molar equivalent of amino groups. The results show that amphiphilic or oil-soluble modified polyethyleneimine polymers with different graft chain amounts and graft lengths can be obtained only by adjusting the reaction molar ratio of the branched polyethyleneimine to the N-sulfonyl aziridine.

Test example 1

The products obtained in example 2 and example 7 were taken, together with a branched polyethyleneimine having a molecular weight of 1800. The raw materials with equal molar mass are weighed and dissolved in a mixed solution of tetrahydrofuran and water with a ratio of 4:1, and then the fluorescence performance is tested by a fluorescence spectrometer, and the fluorescence spectrograms of the products prepared in the application examples 2 and 7 and the branched polyethyleneimine with the number average molecular weight of 1800 are shown in figure 5.

FIG. 5 shows that the fluorescence intensity of the product obtained in example 2 is not much different from that of the unmodified branched polyethyleneimine, but the fluorescence intensity at around 458nm becomes slightly stronger, indicating that the ring-opening grafting of N-sulfonylaziridine to the branched polyethyleneimine causes an increase in the fluorescence intensity at 458 nm. Compared with unmodified branched polyethyleneimine, the fluorescence intensity of example 7 is increased by 10 times at 458nm, which shows that the grafting amount can be obviously increased after initiating the anionic ring-opening polymerization reaction of N-sulfonyl aziridine, and the fluorescence intensity of the branched polyethyleneimine can be increased by increasing the grafted chain.

Test example 2

Preparing ionic solutions containing iron, copper, zinc, chromium, nickel, cobalt and manganese with the concentration of 1 gram per liter, taking 30 mg of the products prepared in the embodiments 1-9, respectively adding the products into 1 ml of the prepared ionic solutions, stirring for 3 hours, centrifuging to remove solids, diluting the ionic solutions, obtaining the ion concentration before and after adsorption of each metal through an atomic absorption spectrometer test, wherein the change of the metal ion concentration in the ionic solutions before and after adsorption of the products prepared in the embodiments 1-9 is shown in table 1.

TABLE 1 Change in Metal ion concentration in Ionic solution before and after adsorption of the products prepared in examples 1-9

Table 1 shows that the adsorption efficiency of the products prepared in examples 1-4 to each metal ion reaches 100%, the products have strong adsorption performance, and the defects of difficult separation and recovery, easy loss and the like do not exist. It should be noted that in examples 1 to 4, due to too small grafting amount, the material is biased to be hydrophilic, which may cause a small amount of material to be dissolved in water during the metal adsorption process, resulting in a small experimental error, and thus the measured adsorption efficiencies are all 100%. The products obtained in examples 6 to 9 had lower adsorption efficiency, and may have reduced adsorption performance due to less polyethyleneimine. The product obtained in example 5 has good metal adsorption efficiency for copper, iron and zinc and adsorption selectivity. The result shows that compared with unmodified water-soluble polyethyleneimine, the modified polyethyleneimine polymer is a solid non-viscous liquid, is insoluble in water, is easier to operate, separate and recover, is not easy to run off, can be used for metal ion adsorption, and has high adsorption efficiency.

Test example 3

30 mg of the product prepared in example 5 is added into 1 ml of iron ion solution with the concentration of 1 g per liter and stirred for 3 hours, the supernatant liquid is centrifugally separated, the solid is washed by 1% of dilute nitric acid and deionized water, 1 ml of iron ion solution is added and stirred for 3 hours after washing, the steps are repeated for 5 times, the concentration of metal ions is tested by an atomic absorption spectrometer after the supernatant liquid after each centrifugation is diluted, and the adsorption efficiency of the product prepared in example 5 on the iron ions is circulated for 5 times as shown in table 2.

TABLE 2 iron ion adsorption efficiency of the product obtained in example 5 with 5 cycles

Table 2 shows that the adsorption efficiency of the product obtained in example 5 after 5 successive adsorbtions is substantially unchanged, and the slight decrease in adsorption efficiency after recycling may be caused by the loss of solids during separation of the supernatant liquor and washing of the solids and incomplete removal of part of the dilute nitric acid. The modified polyethyleneimine polymer can be recycled, and the performance is basically maintained.

The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.