Secondary crosslinking resin and preparation method thereof

Abstract

The invention discloses a preparation method of secondary cross-linked resin and the secondary cross-linked resin, and relates to the technical field of high-molecular polymers. The preparation method comprises the following steps: adding a cross-linking agent with a disulfide bond in the synthesis process of polystyrene resin for reaction to prepare first cross-linked resin containing the disulfide bond; reducing the disulfide bond in the first cross-linked resin into sulfydryl by using a reducing agent to prepare sulfydryl-containing second cross-linked resin; and carrying out sulfydryl-alkene click reaction on residual double bonds in the second cross-linked resin and sulfydryl to prepare the secondary cross-linked resin. The invention aims to solve the problem that an existing adsorbent is poor in adsorption effect and separation effect on target substances.

Description

Technical Field

[0001] The invention relates to the technical field of high molecular polymers, and in particular to a preparation method of a secondary cross-linked resin and the secondary cross-linked resin. Background Art

[0002] Due to its stable chemical properties, polystyrene resins have been used as adsorbents in the fields of blood purification, gas adsorption, wastewater treatment, etc. Since polystyrene resin adsorbents have a specific pore structure, they can adsorb and separate target substances. With the continuous expansion of application fields, higher requirements are also put forward for adsorbents, especially in the blood purification industry. The strength, stability and monomer residue of the adsorbent are all important indicators affecting its safety.

[0003] However, polystyrene resin adsorbents generally use single-crosslinked polystyrene resins, and the parameters such as specific surface area, pore volume and average pore size of single-crosslinked polystyrene resins cannot meet the requirements of existing adsorbents, which leads to poor adsorption and separation effects of the adsorbent on the target substance. Summary of the invention

[0004] The invention provides a preparation method of a secondary cross-linked resin and the secondary cross-linked resin, aiming to solve the problem that the existing adsorbent has poor adsorption effect and separation effect on target substances.

[0005] In a first aspect, the present invention provides a method for preparing a secondary cross-linked resin, the method comprising:

[0006] During the synthesis of the polystyrene resin, a cross-linking agent having a disulfide bond is added to react to obtain a first cross-linking resin containing a disulfide bond;

[0007] Using a reducing agent to reduce the disulfide bonds in the first cross-linked resin to thiol groups, thereby obtaining a second cross-linked resin containing thiol groups;

[0008] The residual double bonds in the second cross-linked resin are subjected to a thiol-ene click reaction with the thiol group to prepare a secondary cross-linked resin.

[0009] In a second aspect, the present invention provides a secondary cross-linked resin, which is prepared by using the above-mentioned preparation method.

[0010] The present invention provides a secondary cross-linked resin and a preparation method thereof. A cross-linking agent having a disulfide bond is added to react during the synthesis of a polystyrene resin to obtain a first cross-linked resin containing a disulfide bond; a reducing agent is used to reduce the disulfide bond in the first cross-linked resin to a thiol group to obtain a second cross-linked resin containing a thiol group; and a thiol-ene click reaction is performed between the residual double bonds in the second cross-linked resin and the thiol group to obtain a secondary cross-linked resin. The secondary cross-linked resin obtained by the present invention has a large specific surface area, a small average pore size, a high strength and a large number of micropores, providing application space for subsequent broad-spectrum adsorption of the resin. If the secondary cross-linked resin is used as an adsorbent, the adsorption effect and separation effect of the adsorbent on the target substance can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0012] Figure 1 It is a schematic flow chart of the steps of a method for preparing a secondary cross-linked resin provided by an embodiment of the present invention;

[0013] Figure 2 It is a schematic flow chart of the steps of another method for preparing a secondary cross-linked resin provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0016] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0017] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0018] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0019] In the related art, the polystyrene resin adsorbent can also use a secondary cross-linked polystyrene resin, and the secondary cross-linked polystyrene resin is prepared by a chloromethyl ether process. However, chloromethyl ether is a type of carcinogen with high toxicity, and there are certain safety hazards in the preparation process. In addition, there may be residual chloromethyl ether in the prepared resin, and its application range may be limited.

[0020] The present invention provides a secondary cross-linked resin and a preparation method thereof. A cross-linking agent having a disulfide bond can be introduced into the synthesis process of a polystyrene resin, so that the disulfide bond is reduced to a thiol group and then secondary cross-linked with the residual double bond to generate a secondary cross-linked resin. The secondary cross-linked resin has a larger specific surface area, a smaller average pore size, a higher strength and more micropores, thereby providing application space for subsequent broad-spectrum adsorption of the resin. If the secondary cross-linked resin is used as an adsorbent, the adsorption effect and separation effect of the adsorbent on the target substance can also be improved.

[0021] The target substance may be organic matter such as toxins, ions, pigments, organic pollutants and the like, or other harmful substances such as heavy metals.

[0022] See also Figure 1 , Figure 1 The present invention provides a schematic flow chart of a method for preparing a secondary cross-linked resin.

[0023] like Figure 1 As shown, the method for preparing the secondary cross-linked resin includes: step S101 to step S103.

[0024] S101. During the synthesis process of a polystyrene resin, a cross-linking agent having a disulfide bond is added to react to obtain a first cross-linked resin containing a disulfide bond.

[0025] The first cross-linked resin is a primary cross-linked polystyrene resin, and the first cross-linked resin contains a disulfide bond provided by a cross-linking agent.

[0026] Since a cross-linking agent having a disulfide bond is added during the synthesis of the polystyrene resin and a polymerization reaction is performed, the first cross-linked resin obtained after the polymerization reaction also contains a disulfide bond.

[0027] For example, the cross-linking agent may be a material such as N,N'-bis(acryl)cystamine that can provide disulfide bonds and carbon-carbon double bonds for cross-linking, and is not specifically limited here.

[0028] Preferably, the cross-linking agent can be N,N'-bis(acryl)cystamine. N,N'-bis(acryl)cystamine not only has a disulfide bond, but also has two carbon-carbon double bonds at the end for cross-linking. Therefore, N,N'-bis(acryl)cystamine used as a cross-linking agent can ensure that the disulfide bond will not fall off when it is subsequently reduced to a thiol group, thereby effectively improving the preparation stability of the secondary cross-linked resin.

[0029] S102, using a reducing agent to reduce the disulfide bonds in the first cross-linked resin to thiol groups, to obtain a second cross-linked resin containing thiol groups.

[0030] The second cross-linked resin is a primary cross-linked polystyrene resin, and the second cross-linked resin contains a thiol group generated by reducing a disulfide bond.

[0031] Exemplarily, the reducing agent can be selected from one or more of dithiothreitol, 2-mercaptoethanol, and tris(2-formylethyl)phosphine hydrochloride, which are not specifically limited herein. The reducing agent can effectively reduce the disulfide bonds in the first cross-linked resin to sulfhydryl groups, so the second cross-linked resin obtained after the reduction reaction will contain sulfhydryl groups.

[0032] In some embodiments, the second cross-linking resin has a thiol content of 0.05-0.8 mmol / mL.

[0033] The content of the mercapto group in the second cross-linking resin can be determined according to the content of the cross-linking agent.

[0034] Generally, the content of thiol groups can be controlled by controlling the amount of cross-linking agent with disulfide bonds added. Generally, the more the amount of cross-linking agent with disulfide bonds added, the more thiol groups content of the second cross-linked resin obtained after the reduction reaction, and the more sufficient the subsequent secondary cross-linking reaction, so that the number of micropores formed in the secondary cross-linked resin is greater, the specific surface area of ​​the secondary cross-linked resin is larger, the pore volume of the secondary cross-linked resin is smaller, and the average pore size of the secondary cross-linked resin is smaller.

[0035] If the thiol content of the second cross-linked resin is too low, it will affect the efficiency of the subsequent secondary cross-linking; if the thiol content of the second cross-linked resin is too high, it means that the amount of cross-linking agent added is too much, which is not conducive to the sphering of the resin. Therefore, it is necessary to adjust the proportion of each material in the synthesis process of the polystyrene resin to re-prepare the primary cross-linked resin. Therefore, the secondary cross-linking reaction effect is best when the thiol content of the second cross-linked resin is controlled to 0.05-0.8 mmol / mL.

[0036] The primary cross-linked resin containing disulfide bonds obtained by the above preparation method is the second cross-linked resin. Performance tests show that the particle size of the second cross-linked resin is between 0.4 and 0.6 mm, and the specific surface area (BET) of the second cross-linked resin is between 200 and 400 m 2 / g; the pore volume of the second cross-linked resin is 1.2-1.8cm 3 / g; the average pore size of the second cross-linked resin is between 14-20nm, and the thiol content of the second cross-linked resin is between 0.05-0.8mmo l / mL.

[0037] S103, performing a thiol-ene click reaction on the residual double bonds in the second cross-linked resin and the thiol groups to obtain a secondary cross-linked resin.

[0038] The residual double bonds are the unreacted carbon-carbon double bonds remaining in the second cross-linked resin, and the secondary cross-linked resin is a polystyrene resin after the residual double bonds are secondary cross-linked with mercapto groups.

[0039] Since there are both residual unreacted carbon-carbon double bonds and thiol groups in the second crosslinked resin, the residual double bonds can be crosslinked with the thiol groups through a thiol-ene click reaction, thereby enabling the first crosslinked second crosslinked resin to self-crosslink to obtain a secondary crosslinked resin.

[0040] The secondary cross-linked resin prepared by the above preparation method has a specific surface area (BET) of 400-1000m 2 / g; pore volume is between 0.8-1.2cm 3 / g; the average pore size is between 7-14nm. Compared with the once cross-linked resin provided by related technologies, performance parameters such as specific surface area and strength are significantly improved.

[0041] The preparation method of the secondary cross-linked resin provided in the embodiment of the present application introduces a cross-linking agent with a disulfide bond during the synthesis of the polystyrene resin, so that the disulfide bonds are reduced to thiol groups and then cross-linked with the residual double bonds to generate a secondary cross-linked resin. The secondary cross-linked resin has a larger specific surface area, a smaller average pore size, a higher strength and more micropores, which provides application space for the subsequent broad-spectrum adsorption of the resin. If the secondary cross-linked resin is used to prepare an adsorbent, the adsorption effect and separation effect of the adsorbent on the target substance can also be improved.

[0042] See also Figure 2 , Figure 2 It is a schematic flow chart of another method for preparing a secondary cross-linked resin provided in an embodiment of the present invention.

[0043] like Figure 2As shown, the preparation method of the secondary cross-linked resin includes the following steps: step S201 to step S203.

[0044] S201, polymerizing styrene monomers, polyvinyl monomers, N,N'-bis(acryl)cystamine, porogens and initiators to obtain a first cross-linked resin containing disulfide bonds.

[0045] Among them, styrene monomers are the main raw materials for the production of polystyrene, and polyvinyl monomers are materials containing two or more vinyl groups in the molecule. Polyvinyl monomers can form cross-linked structures during the polymerization process, thereby enhancing the performance of the polymer. N,N'-bis(acryl)cystamine can provide disulfide bonds, which can be subsequently reduced to thiol groups, so that the subsequent thiol groups and residual double bonds can be cross-linked for secondary cross-linking.

[0046] Exemplarily, if the total mass of styrene monomers, polyvinyl monomers and N,N'-bis(acryl)cystamine is X, the mass of styrene monomers is 15%-40% of X, for example: 15%, 20%, 25%, 40%, etc.; the mass of polyvinylbenzene monomers is 20%-80% of X, for example: 20%, 50%, 65%, 80%, etc.; the mass of N,N'-bis(acryl)cystamine is 5%-50% of X, for example: 5%, 20%, 35%, 50%, etc.

[0047] For example, the styrene monomer may be one or more of styrene, methylstyrene, ethylstyrene, dimethylstyrene, and trimethylstyrene, which are not specifically limited herein.

[0048] Exemplarily, the polyvinyl monomer can be one or more of divinylbenzene, trivinylbenzene, and divinyltoluene, without specific limitation herein. Such polyvinyl aromatic monomer plays a primary cross-linking role, and is copolymerized with styrene monomers to obtain the primary cross-linked resin containing residual dangling double bonds, which are used for secondary cross-linking in subsequent steps.

[0049] If styrene is selected as the styrene monomer and divinylbenzene is selected as the polyvinyl monomer, the mass of styrene can be 25% of X, the mass of divinylbenzene can be 60% of X, and the mass of N,N'-bis(acryl)cystamine can be 15% of X.

[0050] If dimethylstyrene is used as the styrene monomer and divinyltoluene is used as the polyvinyl monomer, the mass of dimethylstyrene can be 30% of X, the mass of divinyltoluene can be 50% of X, and the mass of N,N'-bis(acryl)cystamine can be 20% of X.

[0051] Exemplarily, the porogen is mainly composed of long-chain alkanes, aromatic hydrocarbons, and higher fatty alcohols, wherein long-chain alkanes refer to alkanes with more carbon atoms, usually 20 or more carbon atoms, and a long and complex molecular structure. The mass of the porogen can be 50%-150% of X.

[0052] Specifically, if the total mass of the porogen is Y, the mass of the long-chain alkane is 0-50% of Y, for example: 0%, 20%, 35%, 50%, etc.; the mass of the aromatic hydrocarbon is 30-60% of Y, for example: 30%, 40%, 55%, 60%, etc.; the mass of the higher fatty alcohol is 20-50% of Y, for example: 20%, 30%, 45%, 50%, etc.

[0053] For example, the long-chain alkane may be one or more of white oil and gasoline, which are not specifically limited herein.

[0054] For example, the aromatic hydrocarbon may be one or more of toluene, ethylbenzene, and xylene, which are not specifically limited herein.

[0055] For example, the higher fatty alcohol may be one or more of isooctyl alcohol, methyl isobutyl carbinol, and n-heptanol, which are not specifically limited herein.

[0056] If toluene and isooctyl alcohol are selected as the porogen, the mass of toluene can be 60% of Y, and the mass of isooctyl alcohol can be 40% of Y.

[0057] If the porogen is white oil, ethylbenzene and methyl isobutyl carbinol, the mass of the white oil can be 20% of Y, the mass of the ethylbenzene can be 50% of Y, and the mass of the methyl isobutyl carbinol can be 30% of Y.

[0058] For example, the initiator can be selected from one or more of azobisisobutyronitrile, benzoyl peroxide and tert-butyl perbenzoate, which are not specifically limited here. The mass of the initiator can be 0.5%-5% of X, for example: 0.5%, 1%, 3%, 5%, etc.

[0059] Specifically, a suspension polymerization method is used to uniformly mix styrene monomers, polyvinyl monomers, N,N'-bis(acryl)cystamine, a porogen and an initiator to obtain an oil phase solution; the oil phase solution is added to an aqueous phase solution to allow the styrene monomers, polyvinyl monomers, N,N'-bis(acryl)cystamine, a porogen and an initiator to undergo a suspension polymerization reaction to obtain a first cross-linked resin containing a disulfide bond; the reaction conditions of the polymerization reaction include: a reaction stirring speed of 120-180 rpm, a reaction temperature of 70-90°C, and a reaction time of 6-18 hours.

[0060] The oil phase solution is a mixture of styrene monomers, polyvinyl monomers, N,N'-bis(acryl)cystamine, porogen and initiator, and the water phase solution is a water-soluble organic polymer solution, which serves as a dispersion medium.

[0061] For example, the water-soluble organic polymer can be selected from one or more of hydroxymethyl cellulose, hydroxyethyl cellulose, chitosan, polyacrylic acid, sodium polyacrylate and gelatin as a dispersant, which is not specifically limited here. The concentration of the water-soluble organic polymer in the aqueous phase solution can be 0.05%-0.5%wt, for example: 0.05%wt, 0.2%wt, 0.3%wt%, 0.5%wt, etc.

[0062] Exemplarily, it is assumed that the reaction conditions of the polymerization reaction include: a reaction stirring speed of 140 rpm, a reaction temperature of 75°C, and a reaction time of 8 hours. Specifically, the oil phase solution and the aqueous phase solution are mixed, and the reaction is continuously stirred at a speed of 140 rpm for 8 hours at a reaction temperature of 75°C. After the reaction is completed, the mixture generated after the polymerization reaction is washed with clean water to remove excess impurities, and the mixture is continuously subjected to resin extraction treatment with acetone using a Soxhlet extractor for 24 hours, and then dried, and a resin with a particle size between 0.4-0.6 mm is selected as a primary cross-linked resin containing a disulfide bond, i.e., the first cross-linked resin.

[0063] S202, using a reducing agent to reduce the disulfide bonds in the first cross-linked resin to thiol groups, to obtain a second cross-linked resin containing thiol groups.

[0064] Specifically, the reducing solution is mixed with the first cross-linking resin to perform a reducing reaction, the reducing solution is prepared from a reducing agent and a buffer solution, and the reaction conditions of the reducing reaction include: a reaction temperature of 25-60° C. and a reaction time of 8-48 hours.

[0065] The volume ratio of the reducing solution to the first cross-linking resin is 1:1 to 3:1.

[0066] In the synthesis process of polystyrene resin, a cross-linking agent with a disulfide bond is added in the form of a reactive monomer, and then the disulfide bond is reduced to a thiol group, so that a thiol group can be introduced on the skeleton surface of the polystyrene resin, providing a thiol group and other reactive groups for subsequent secondary cross-linking. The thiol group introduced in this way has good stability, and by controlling the amount of the cross-linking agent with a disulfide bond added, the thiol content of the resin can be effectively adjusted. Compared with the method of grafting thiol groups in the form of ligands, the present application can effectively avoid the problems of unstable grafting and uncontrollable grafting amount.

[0067] Exemplarily, the buffer solution and the reducing agent are mixed evenly to obtain a reducing solution, the pH value of the buffer solution is 7-8, and the concentration of the reducing solution is 1-10%wt.

[0068] The buffer solution may be a phosphate buffered saline solution (PBS buffer solution), and the concentration of the reducing solution may be 1-10% wt, for example, 1% wt, 5% wt, 10% wt, and the like.

[0069] Exemplarily, the buffer solution can be prepared from materials such as potassium dihydrogen phosphate, disodium hydrogen phosphate, sodium chloride and potassium chloride in different proportions, and the pH value of the buffer solution is controlled to be between 7 and 8.

[0070] Exemplarily, the reducing agent may be one or more of dithiothreitol, 2-mercaptoethanol, and tris(2-formylethyl)phosphine hydrochloride, which are not specifically limited herein.

[0071] For example, it is assumed that the reaction conditions of the reduction reaction include: a reaction temperature of 50°C and a reaction time of 40 hours. Under a reaction temperature of 50°C, the volume ratio of the reducing solution to the first cross-linked resin is controlled to be 2:1, and the first cross-linked resin reacts in the reducing solution for 40 hours. After the reaction is completed, the excess buffer and reducing agent are washed with clean water to avoid the residual buffer and reducing agent from affecting the subsequent secondary cross-linking, thereby obtaining a thiol-containing primary cross-linked resin, i.e., a second cross-linked resin.

[0072] It should be noted that it is generally necessary to control the use of excessive reducing solution to reduce all disulfide bonds on the first cross-linked resin to thiol groups.

[0073] The primary cross-linked resin containing disulfide bonds obtained by the above preparation method is the second cross-linked resin. Performance tests show that the particle size of the second cross-linked resin is between 0.4-0.6 mm, and the specific surface area of ​​the second cross-linked resin is between 200-400 m 2 / g; the pore volume of the second cross-linked resin is 1.2-1.8cm 3 / g; the average pore size of the second cross-linked resin is between 14-20nm, and the thiol content of the second cross-linked resin is between 0.05-0.8mmo l / mL.

[0074] S203, after swelling the second cross-linked resin, in the presence of an initiator, the residual double bonds in the second cross-linked resin react with the thiol groups to produce a thiol-ene click reaction to obtain a secondary cross-linked resin.

[0075] The residual double bonds are the unreacted carbon-carbon double bonds remaining in the second cross-linked resin, and the secondary cross-linked resin is a polystyrene resin after the residual double bonds are secondary cross-linked with mercapto groups.

[0076] Specifically, the second cross-linked resin is swelled with an alcohol solvent, and the swelled second cross-linked resin is mixed with a thermal initiator, so that the residual double bonds in the second cross-linked resin undergo a thiol-ene click reaction with the thiol groups to prepare the secondary cross-linked resin.

[0077] The volume ratio of the alcohol solvent to the second cross-linking resin is 1:1 to 2:1, and the reaction conditions of the thiol-ene click reaction include: a reaction temperature of 40-80° C. and a reaction time of 6-18 hours.

[0078] Taking into account the swelling effect of the second cross-linked resin, since the polarity of the thiol group is similar to that of the alcohol solvent, the thiol group has better expansion in the alcohol solvent, which is beneficial to the subsequent reaction. In order to make the second cross-linked resin swell better, it is preferred to swell the second cross-linked resin with an alcohol solvent.

[0079] For example, the alcohol solvent may be one or more of methanol, ethanol, isopropanol and n-butanol, which are not specifically limited herein. The volume ratio of the alcohol solvent to the second cross-linking resin may be controlled between 1:1 and 2:1, which is conducive to full swelling.

[0080] For example, the thermal initiator can be selected from one or more of di-tert-butyl peroxide, azobisisoheptonitrile and diisopropyl peroxydicarbonate, which are not specifically limited herein. The mass of the thermal initiator accounts for 0.5-5% of the total mass of the second cross-linked resin, for example, 0.5%, 2%, 5%, etc.

[0081] Exemplarily, it is assumed that the reaction conditions of the thiol-ene click reaction include: a reaction temperature of 50°C and a reaction time of 12 hours. The volume ratio of the alcohol solvent to the second cross-linked resin is controlled to be 2:1, and the second cross-linked resin is added to the alcohol solvent to swell the second cross-linked resin. After the second cross-linked resin swells, the reaction temperature is controlled to 50°C, and the swollen second cross-linked resin is mixed with a thermal initiator and self-cross-linked for 12 hours using a thiol-ene click reaction. After the reaction is completed, the secondary cross-linked resin is obtained by drying.

[0082] The secondary cross-linked resin is prepared by the above preparation method. Performance tests show that the specific surface area of ​​the secondary cross-linked resin is 400-1000m 2 / g; pore volume is between 0.8-1.2cm 3 / g; the average pore size is between 7-14nm. Compared with the once cross-linked resin provided by related technologies, performance parameters such as specific surface area and strength are significantly improved.

[0083] The preparation method and properties of the secondary cross-linked resin of the present application are described below through specific examples.

[0084] Embodiment 1:

[0085] (1) Add 400 mL of 0.2% wt gelatin aqueous solution to a 1000 mL three-necked flask as an aqueous solution. Add reaction monomers, porogens and initiators to a beaker, stir evenly, and prepare an oil phase solution, wherein the reaction monomers include 15 g of styrene, 6 g of ethyl styrene, 24 g of divinyl benzene and 40 g of N, N'-bis (acryl) cystamine; the porogen includes 60 g of toluene and 60 g of methyl isobutyl carbinol; and the initiator includes 1 g of benzoyl peroxide. Add the oil phase solution to the aqueous solution, and stir the reaction at a reaction temperature of 75°C and a speed of 140 rpm for 8 hours. After the reaction is completed, wash the resin with water to remove excess impurities, and then use a Soxhlet extractor to extract the resin mixture with acetone for 24 hours, and then dry and sieve to select a resin with a particle size between 0.4 and 0.6 mm, thereby obtaining a primary cross-linked resin containing disulfide bonds, i.e., the first cross-linked resin.

[0086] (2) Take 100 mL of the first cross-linked resin obtained in step (1) in a three-necked flask; prepare 200 mL of PBS buffer solution with a pH of 7.4, add 5 g of dithiothreitol, add it to the three-necked flask after it is completely dissolved, and react at 40° C. for 24 hours. After the reaction is completed, remove the remaining dithiothreitol and PBS buffer solution with a large amount of water to obtain a primary cross-linked resin containing thiol groups, i.e., a second cross-linked resin, wherein the thiol content in the second cross-linked resin is 0.5 mmol / mL.

[0087] (3) Take 20 g of the second cross-linked resin obtained in step (2) in another three-necked flask, add 150 mL of ethanol, stir and fully swell, then add 0.2 g of di-tert-butyl peroxide, and react at 60° C. for 18 hours. After the reaction is completed, dry to obtain the secondary cross-linked resin.

[0088] Embodiment 2:

[0089] (1) Add 400 mL of 0.08% wt hydroxyethyl cellulose aqueous solution to a 1000 mL three-necked flask as an aqueous solution. Add reaction monomers, porogens and initiators to a beaker, stir evenly, and prepare an oil phase solution, wherein the reaction monomers include 18 g of styrene, 16 g of ethyl styrene, 24 g of divinyl benzene and 32 g of N, N'-bis(acryl) cystamine; the porogen includes 30 g of white oil, 45 g of toluene and 35 g of isooctyl alcohol; the initiator includes 1.5 g of azobisisobutyronitrile. Add the oil phase solution to the aqueous solution, and stir the reaction at a reaction temperature of 80°C and a rotation speed of 160 rpm for 12 hours. After the reaction is completed, the resin is washed with water to remove excess impurities, and then the resin mixture is extracted with acetone using a Soxhlet extractor for 24 hours, and then dried and sieved to select a resin with a particle size between 0.4 and 0.6 mm, thereby obtaining a primary cross-linked resin containing disulfide bonds, namely the first cross-linked resin.

[0090] (2) Take 150 mL of the first cross-linked resin obtained in step (1) in a three-necked flask; prepare 250 mL of PBS buffer solution with a pH of 7.4, add 6.3 g of dithiothreitol, add it to the three-necked flask after it is completely dissolved, and react at 35° C. for 36 hours. After the reaction is completed, remove the remaining dithiothreitol and PBS buffer solution with a large amount of water to obtain a primary cross-linked resin containing thiol groups, i.e., a second cross-linked resin, wherein the thiol content in the second cross-linked resin is 0.37 mmol / mL.

[0091] (3) Take 50 g of the second cross-linked resin obtained in step (2) in another three-necked flask, add 280 mL of methanol, stir and fully swell, then add 0.34 g of azobisisoheptanenitrile, and react at 70° C. for 12 hours. After the reaction is completed, dry to obtain the secondary cross-linked resin.

[0092] Embodiment 3:

[0093] (1) Add 400 mL of polyacrylic acid aqueous solution with a concentration of 0.2% wt to a 1000 mL three-necked flask as an aqueous solution. Add reaction monomers, porogens and initiators to a beaker, stir evenly, and prepare an oil phase solution. Stir evenly to prepare an oil phase solution, wherein the reaction monomers include 30 g of methyl styrene, 4 g of ethyl styrene, 16 g of divinyl benzene and 48 g of N, N'-bis (acryl) cystamine; the porogen includes 30 g of gasoline, 45 g of xylene and 35 g of n-heptanol; the initiator includes 1.5 g of azobisisobutyronitrile. Add the oil phase solution to the aqueous solution, and stir the reaction at a reaction temperature of 85°C and a rotation speed of 120 rpm for 8 hours. After the reaction is completed, the resin is washed with water to remove excess impurities, and then the resin mixture is extracted with acetone using a Soxhlet extractor for 24 hours, and then dried and sieved to select a resin with a particle size between 0.4 and 0.6 mm, thereby obtaining a primary cross-linked resin containing disulfide bonds, namely the first cross-linked resin.

[0094] (2) 180 mL of the first cross-linked resin obtained in step (1) was placed in a three-necked flask; 300 mL of PBS buffer solution with a pH of 7.4 was prepared, and 5.5 g of dithiothreitol was added, and after it was completely dissolved, it was added to the three-necked flask, and reacted at 50° C. for 48 hours. After the reaction was completed, the remaining dithiothreitol and PBS buffer solution were removed with a large amount of water to obtain a primary cross-linked resin containing thiol groups, i.e., a second cross-linked resin, wherein the thiol content in the second cross-linked resin was 0.43 mmol / mL.

[0095] (3) Take 35 g of the second cross-linked resin obtained in step (2) in another three-necked flask, add 200 mL of isopropanol, stir and fully swell, then add 0.24 g of diisopropyl peroxydicarbonate, and react at 60° C. for 8 hours. After the reaction is completed, dry to obtain a secondary cross-linked resin.

[0096] It should be noted that the resin of Comparative Example 1 is the second cross-linked resin obtained in step (2) of Example 1, the resin of Comparative Example 2 is the second cross-linked resin obtained in step (2) of Example 2, and the resin of Comparative Example 3 is the second cross-linked resin obtained in step (2) of Example 3.

[0097] The performance test was conducted using the secondary cross-linked resin provided in the above embodiment and the second cross-linked resin provided in the above comparative example. The performance test experimental data are shown in Table 1 and Table 2.

[0098] Table 1

[0099] <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Pore volume (cm 3 / g)]]> Average pore size (nm) Example 1 680 0.9 10.2 Comparative Example 1 246 1.5 15.8 Example 2 742 0.8 9.6 Comparative Example 2 360 1.3 14.6 Example 3 644 1.0 10.7 Comparative Example 3 338 1.3 14.2

[0100] Table 2

[0101]

[0102]

[0103] Through the test results of Table 1 and Table 2, it is found that the secondary cross-linked resin prepared in the embodiment of the present application has a significantly increased specific surface area and a reduced average pore size compared to the primary cross-linked resin, and more micropores are generated during the secondary cross-linking process. This is because some of the medium and large pores are transformed into micropores or mesopores through secondary cross-linking, and the pore structure is more perfect. At the same time, the strength of the secondary cross-linked resin generated in the embodiment of the present application is higher than that of the primary cross-linked resin. In summary, the secondary cross-linked resin prepared in the embodiment of the present application not only does not have residual toxic substances such as chloromethyl ether, but also has a larger specific surface area, a smaller average pore size, a higher strength and more micropores, which provides application space for the subsequent broad-spectrum adsorption of the resin, and improves the adsorption effect and separation effect of the adsorbent on the target substance.

[0104] The present application also provides a secondary cross-linked resin, which is prepared by using the preparation method provided by any of the above embodiments.

[0105] Among them, the specific method of preparing the secondary cross-linked resin can refer to the corresponding embodiment recorded in the specification of this application, and this embodiment will not be repeated here. The secondary cross-linked resin provided in the embodiment of the present application does not leave any toxic substances such as chloromethyl ether, and also has a large specific surface area, a small average pore size, a high strength and a large number of micropores, thereby providing application space for the subsequent broad-spectrum adsorption of the resin and improving the adsorption effect and separation effect of the adsorbent on the target substance.

[0106] Specifically, the specific surface area of ​​the secondary cross-linked resin provided in the embodiment of the present application is 400-1000m 2 / g; pore volume is between 0.8-1.2cm 3 / g; the average pore size is between 7-14nm. Compared with the once cross-linked resin provided by related technologies, performance parameters such as specific surface area and strength are significantly improved.

[0107] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing a secondary cross-linked resin, characterized in that: include: During the synthesis of the polystyrene resin, a cross-linking agent having a disulfide bond is added to react to obtain a first cross-linking resin containing a disulfide bond; Using a reducing agent to reduce the disulfide bonds in the first cross-linked resin to thiol groups, thereby obtaining a second cross-linked resin containing thiol groups; The residual double bonds in the second cross-linked resin are subjected to a thiol-ene click reaction with the thiol group to prepare a secondary cross-linked resin.

2. The preparation method according to claim 1, characterized in that: The cross-linking agent is N,N'-bis(acryl)cystamine.

3. The preparation method according to claim 1, characterized in that: The reducing agent is selected from one or more of dithiothreitol, 2-mercaptoethanol, and tris(2-formylethyl)phosphine hydrochloride.

4. The preparation method according to claim 1, characterized in that: The second cross-linked resin has a thiol content of 0.05-0.8 mmol / mL.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The steps include: The styrene monomer, the polyvinyl monomer, N,N'-bis(acryl)cystamine, the porogen and the initiator are polymerized to obtain a first cross-linked resin containing a disulfide bond; Using a reducing agent to reduce the disulfide bonds in the first cross-linked resin to thiol groups, thereby obtaining a second cross-linked resin containing thiol groups; After the second cross-linked resin is swollen, in the presence of an initiator, the residual double bonds in the second cross-linked resin undergo a thiol-ene click reaction with the thiol groups to obtain a secondary cross-linked resin.

6. The preparation method according to claim 5, characterized in that: The styrene monomer is one or more of styrene, methyl styrene, ethyl styrene, dimethyl styrene, and trimethyl styrene; the polyvinyl monomer is one or more of divinyl benzene, trivinyl benzene, and divinyl toluene; The total mass of the styrene monomer, the polyvinyl monomer and the N,N'-bis(acryl)cystamine is X, the mass of the styrene monomer is 15%-40% of X, the mass of the polyvinyl monomer is 20%-80% of X, and the mass of the N,N'-bis(acryl)cystamine is 5%-50% of X.

7. The preparation method according to claim 5, characterized in that: The polymerization reaction is a suspension polymerization reaction, and the reaction conditions of the polymerization reaction include: a reaction stirring speed of 120-180 rpm, a reaction temperature of 70-90° C., and a reaction time of 6-18 hours.

8. The preparation method according to claim 5, characterized in that: The method of reducing the disulfide bonds in the first cross-linked resin to thiol groups by using a reducing agent to obtain a second cross-linked resin containing thiol groups comprises: The reducing solution is mixed with the first cross-linking resin to perform a reducing reaction, wherein the reducing solution is prepared from a reducing agent and a buffer solution, and the reaction conditions of the reducing reaction include: a reaction temperature of 25-60° C. and a reaction time of 8-48 hours.

9. The preparation method according to claim 5, characterized in that: The step of swelling the second cross-linked resin comprises: Using an alcohol solvent to swell the second cross-linking resin; The reaction conditions of the thiol-ene click reaction include: a reaction temperature of 40-80° C. and a reaction time of 6-18 hours. 10 . A secondary cross-linked resin obtained by using the preparation method according to claim 1 .

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