Glyoxal modified polyacrylamide and synthesis method thereof

Abstract

The invention belongs to the technical field of high-molecular polymers, and particularly relates to glyoxal modified polyacrylamide and a synthesis method thereof. Comprising the following steps: adding sulphaguanidine and 4-vinyl benzaldehyde into a solvent for reflux to obtain a compound 1; the preparation method comprises the following steps: adding acrylamide and methacryloyloxyethyl trimethyl ammonium chloride into water, adding into the hydrolysate of 1, 3-dimethoxy-1, 3-dimethyl-1, 3-divinyl disiloxane, and adding an ammonium persulfate solution for reaction to obtain a mixed solution; adding an acetone solution of a compound 1 into the mixed solution, and adding an ammonium persulfate solution to react to obtain cationic polyacrylamide; the cationic polyacrylamide and glyoxal are stored separately, and are mixed and reacted during use to obtain glyoxal modified polyacrylamide. According to the invention, early crosslinking of glyoxal and a polymer is avoided, the paper strength can be obviously improved, and the product can show excellent stability in the storage process.

Description

Technical Field

[0001] This invention belongs to the field of polymer technology, specifically relating to a glyoxal-modified polyacrylamide and its synthesis method. Background Technology

[0002] In the papermaking industry, reinforcing agents are key to improving paper strength and are widely used in packaging paper, yarn tube paper, cultural paper and other fields. Glyoxal-modified polyacrylamide (GPAM) has a wider range of applications compared to traditional reinforcing agents. GPAM has stronger chemical bonding ability and specific functions, which can better improve paper strength.

[0003] However, existing GPAM products suffer from significant technical bottlenecks in storage stability, resulting in short shelf lives and causing challenges for both suppliers and users in their inventory and usage plans. Conventional cationic polyacrylamide molecules contain active groups such as amino and amide groups, while glyoxal molecules have two active aldehyde groups, ultimately leading to a shelf life of only 7-90 days for conventional GPAM products. Prolonged storage can cause changes in molecular structure or slow cross-linking reactions due to external humidity and oxygen, resulting in unstable product performance, such as decreased solubility and reduced reinforcing effects, further shortening shelf life. Furthermore, the traditional GPAM content is typically in the range of 2%-12%, making it difficult to increase further, which leads to a significant increase in transportation and packaging costs.

[0004] Therefore, developing a method for synthesizing glyoxal-modified polyacrylamide on-site at the customer's site, with the final product significantly improving the dry strength of paper, being environmentally friendly and non-toxic, and having a longer shelf life, has become an urgent problem to be solved in the paper industry. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the primary objective of this invention is to provide a method for synthesizing glyoxal-modified polyacrylamide, which fundamentally solves the key technical problem of storage stability while maintaining the reinforcing effect of GPAM.

[0006] Another object of the present invention is to provide a glyoxal-modified polyacrylamide.

[0007] The objective of this invention is achieved through the following technical solution: A method for synthesizing glyoxal-modified polyacrylamide includes the following steps: (1) Sulfamethidine and 4-vinylbenzaldehyde were added to a solvent and refluxed; the reaction solution was concentrated, filtered, recrystallized, and dried to obtain compound 1; (2) Add 1,3-dimethoxy-1,3-dimethyl-1,3-divinyldisiloxane to a solvent, and hydrolyze to obtain a hydrolysate; (3) Acrylamide and methacryloyloxyethyltrimethylammonium chloride are added to water to form a mixture A. Mixture A is added to the hydrolysate of step (2), and ammonium persulfate aqueous solution A is added to carry out the first reaction to obtain mixture B. Then, acetone solution containing compound 1 is added to mixture B, and ammonium persulfate aqueous solution B is added to carry out the second reaction to obtain cationic polyacrylamide. (4) Store the cationic polyacrylamide obtained in step (3) separately from glyoxal. When using, mix the cationic polyacrylamide and glyoxal to obtain glyoxal-modified polyacrylamide.

[0008] Further, in step (1), the chemical structural formula of compound 1 is as follows: .

[0009] Further, in step (1), the molar ratio of sulfadiazine to 4-vinylbenzaldehyde is 1:(1-1.1); the volume ratio of sulfadiazine to solvent is 2mol:3-5mL, and the solvent is acetone; the reflux time is 2-3h.

[0010] Further, in step (2), the ratio of 1,3-dimethoxy-1,3-dimethyl-1,3-divinyldisiloxane to solvent is 1g:8-10mL; the solvent is an aqueous ethanol solution with a volume fraction of 70-80%; the pH during hydrolysis is 3.5-4, and the hydrolysis time is 5-6h.

[0011] Further, in step (3), the mass ratio of acrylamide to methacryloyloxyethyltrimethylammonium chloride is (10-12):(2-3), and the ratio of acrylamide to water is (10-12)g:(50-60)mL.

[0012] Further, in step (3), the mass ratio of the mixture A, hydrolysate, ammonium persulfate aqueous solution A, acetone solution containing compound 1, and ammonium persulfate aqueous solution B is (6-8):1:(1-2):(0.3-0.4):(1-2); the concentration of the ammonium persulfate aqueous solution A is 1.5-2wt%; the temperature of the first reaction is 70-75℃ and the time is 1-2h; the concentration of the ammonium persulfate aqueous solution B is 1.5-2wt%; the temperature of the second reaction is 70-75℃ and the time is 2-3h; the ratio of the amount of compound 1 to acetone in the acetone solution containing compound 1 is 2-3g:3-4mL.

[0013] Furthermore, in step (3), the rate of adding mixture A is 0.7-0.8 mL / min; the rates of adding ammonium persulfate aqueous solution A and ammonium persulfate aqueous solution B are both 0.2-0.25 mL / min.

[0014] Further, in step (4), the mass ratio of the cationic polyacrylamide to glyoxal is (1.5-3.5):(0.1-0.9), and the glyoxal is a 40% glyoxal aqueous solution.

[0015] Furthermore, in step (4), the mass ratio of the cationic polyacrylamide to glyoxal is (1.5-3.5):(0.4-0.9), and the glyoxal is a 40% glyoxal aqueous solution.

[0016] Furthermore, the molecular weight of the cationic polyacrylamide is 13,000-100,000.

[0017] A glyoxal-modified polyacrylamide was prepared according to the synthesis method described above.

[0018] The present invention has the following advantages over the prior art: 1. This invention prepares glyoxal-modified polyacrylamide with excellent storage stability through specific molecular design and process optimization: First, this invention utilizes the reaction of the amino group on the sulfadiazine benzene ring with the aldehyde group of 4-vinylbenzaldehyde to generate compound 1. Then, through the hydrolysis of a siloxane containing two double bonds, a silanol containing two double bonds is obtained. This silanol is then crosslinked with the double bonds of acrylamide, methacryloyloxyethyltrimethylammonium chloride, and compound 1 to obtain a cationic polyacrylamide with excellent stability. Specifically, the rigid planar structure of compound 1 effectively inhibits the movement of polymer molecular chains through a large π-conjugated system (benzene ring-imine bond-benzene ring) and steric hindrance effect. Simultaneously, the sulfonyl group forms a hydrogen bond network with adjacent polymer chains, and the imine bond generates d-π coordination with the siloxane, constructing a dynamically stable three-dimensional network. This structure enables the product to exhibit excellent stability during storage. When applied to paper reinforcement, the siloxane bonds and silanol hydroxyl groups form a cross-linked network structure with the hydroxyl groups of cellulose. The benzene ring of compound 1 and lignin undergo π-π stacking, while the quaternary ammonium cations are electrostatically adsorbed onto the fiber surface. Together, these factors significantly improve the paper strength. Secondly, this invention stores cationic polyacrylamide and glyoxal separately, allowing for online mixing and reaction during use. This avoids premature cross-linking of glyoxal with the amino / amide groups in the polymer, resulting in a longer shelf life for the raw materials, ensuring stable product performance, reducing transportation and packaging costs, enabling on-site production and use at the customer's location, and making it suitable for various customer scenarios.

[0019] 2. This invention fundamentally solves the industry problems of short shelf life and unstable performance of traditional GPAM by preparing cationic polyacrylamide with excellent stability and storing cationic polyacrylamide and glyoxal separately and mixing them online. Attached Figure Description

[0020] Figure 1The infrared curve of the cationic polyacrylamide obtained in Example 1 of this invention is shown. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to specific embodiments. However, those skilled in the art should understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all conventional products obtained through commercial channels. Example 1

[0022] A method for synthesizing glyoxal-modified polyacrylamide includes the following steps: (1) Sulfamethidine and 4-vinylbenzaldehyde were added to acetone and refluxed for 2.5 h; the molar ratio of sulfamethidine to 4-vinylbenzaldehyde was 1:1; the molar ratio of sulfamethidine to acetone was 2 mol: 4 mL. The reaction solution was concentrated, filtered, and the crude product was obtained. The crude product was recrystallized with acetone and dried to obtain compound 1 (yield 81.4%). 1 HNMR (C 16 H 16 N4O2S, 400 MHz, d6-DMSO) δ 8.68 (s, 1H)7.85 (s, 1H), 7.81(d, 2H),7.48(d, 2H), 7.40 (d, 2H), 7.25(d, 2H), 6.74(t, 1H), 6.62 (s, 2H), 5.78 (d,1H), 5.26(d, 1H), 2.05 (s, 1H); HRMS (ESI + [M] Calculation yields 328.10, and the value is found to be 328.10.

[0023]

[0024] (2) 1,3-Dimethoxy-1,3-dimethyl-1,3-divinyldisiloxane was added to a 75% ethanol aqueous solution according to a dosage ratio of 1g:9mL. The pH was adjusted to 3.8 using acetic acid and allowed to stand for 5.5h to complete the hydrolysis of silane and obtain the hydrolysate. (3) Add acrylamide and methacryloyloxyethyltrimethylammonium chloride to water, wherein the mass ratio of acrylamide to methacryloyloxyethyltrimethylammonium chloride is 11:2.5, and the volume ratio of acrylamide to water is 11g:55mL; to form mixed solution A; slowly add mixed solution A dropwise to the hydrolysate of step (2) at 0.75 mL / min, while simultaneously adding a solution with a concentration of 1.8 g / mL at 0.25 mL / min. A wt% ammonium persulfate aqueous solution A was added dropwise, and the reaction was continued for 1.5 h at a temperature maintained at 72°C to obtain a mixture B. Then, an acetone solution containing compound 1 (compound 1 to acetone in a ratio of 2.5 g: 3.5 mL) was added dropwise to mixture B, while simultaneously adding a 1.8 wt% ammonium persulfate aqueous solution B at a dropping rate controlled at 0.25 mL / min. The mass ratio of the mixture A, hydrolysate, ammonium persulfate aqueous solution A, acetone solution containing compound 1, and ammonium persulfate aqueous solution B was 7:1:1.5:0.35:1.5. After the addition was complete, the reaction was continued for 2.5 h at a temperature maintained at 72°C to obtain cationic polyacrylamide. The molecular weight of the cationic polyacrylamide was determined using an Ubbelohde viscometer according to GB / T12005.1-1989 and GB / T12005.10-1992, and the molecular weight was found to be 13500.

[0025] (4) Prepare the cationic polyacrylamide obtained in step (3) and the 40% glyoxal aqueous solution at a mass ratio of 1.5:0.4, store them separately, and mix the cationic polyacrylamide and the glyoxal aqueous solution to react and obtain glyoxal-modified polyacrylamide. Example 2

[0026] A method for synthesizing glyoxal-modified polyacrylamide includes the following steps: (1) Sulfamethidine and 4-vinylbenzaldehyde were added to acetone and refluxed for 2 h; the molar ratio of sulfamethidine to 4-vinylbenzaldehyde was 1:1.05; the molar ratio of sulfamethidine to acetone was 2 mol:3 mL. The reaction solution was concentrated, filtered, and the crude product was obtained. The crude product was recrystallized with acetone and dried to obtain compound 1 (yield 80.1%). 1 HNMR and HRMS (ESI) + The results were the same as in Example 1.

[0027] (2) 1,3-Dimethoxy-1,3-dimethyl-1,3-divinyldisiloxane was added to a 70% ethanol aqueous solution according to the dosage ratio of 1g:8mL. The pH was adjusted to 3.5 with acetic acid and allowed to stand for 5 h to complete the hydrolysis of silane and obtain the hydrolysate. (3) Add acrylamide and methacryloyloxyethyltrimethylammonium chloride to water, wherein the mass ratio of acrylamide to methacryloyloxyethyltrimethylammonium chloride is 10:2, and the volume ratio of acrylamide to water is 10g:50mL; to form a mixed solution A; slowly add mixed solution A to the hydrolysate of step (2) at 0.7mL / min, and simultaneously add a 1.5wt% ammonium persulfate aqueous solution A at 0.2mL / min. After the addition is complete, continue the reaction for 2h, and maintain the reaction temperature at 70℃ to obtain mixed solution B; then add an acetone solution containing compound 1 (the volume ratio of compound 1 to acetone is 2g:3mL) to mixed solution B, and simultaneously add a 1.5wt% ammonium persulfate aqueous solution B, with the dropping rate controlled at 0.2mL / min. The mass ratio of mixed solution A, hydrolysate, ammonium persulfate aqueous solution A, acetone solution containing compound 1, and ammonium persulfate aqueous solution B is 6:1:1:0.3:1; after the addition is complete, continue the reaction for 2h. The reaction temperature was maintained at 75℃ for h, and cationic polyacrylamide was obtained. The molecular weight of the cationic polyacrylamide was determined by Ubbelohde viscometer according to GB / T12005.1-1989 and GB / T12005.10-1992. The molecular weight of the cationic polyacrylamide was found to be 13058.

[0028] (4) Prepare the cationic polyacrylamide obtained in step (3) and the glyoxal aqueous solution with a mass fraction of 40% at a mass ratio of 2:0.6, store them separately, and mix the cationic polyacrylamide and the glyoxal aqueous solution to react when used to obtain glyoxal modified polyacrylamide. Example 3

[0029] A method for synthesizing glyoxal-modified polyacrylamide includes the following steps: (1) Sulfamethidine and 4-vinylbenzaldehyde were added to acetone and refluxed for 3 h; the molar ratio of sulfamethidine to 4-vinylbenzaldehyde was 1:1.1; the molar ratio of sulfamethidine to acetone was 2 mol:5 mL. The reaction solution was concentrated, filtered, and the crude product was obtained. The crude product was recrystallized with acetone and dried to obtain compound 1 (yield 81.0%). 1 HNMR and HRMS (ESI) + The results were the same as in Example 1.

[0030] (2) 1,3-Dimethoxy-1,3-dimethyl-1,3-divinyldisiloxane was added to an 80% ethanol aqueous solution according to a dosage ratio of 1 g: 10 mL. The pH was adjusted to 4 using acetic acid and allowed to stand for 6 h to complete the hydrolysis of silane and obtain the hydrolysate. (3) Add acrylamide and methacryloyloxyethyltrimethylammonium chloride to water, wherein the mass ratio of acrylamide to methacryloyloxyethyltrimethylammonium chloride is 12:3, and the volume ratio of acrylamide to water is 12g:60mL; to form a mixed solution A; slowly add mixed solution A to the hydrolysate of step (2) at 0.8 mL / min, and simultaneously add 2wt% ammonium persulfate aqueous solution A at 0.25 mL / min, and continue the reaction for 1 hour after the addition is completed, keeping the reaction temperature at 75℃ to obtain mixed solution B; then add acetone solution containing compound 1 (the volume ratio of compound 1 to acetone is 3 g:4mL) to mixed solution B, and simultaneously add 2wt% ammonium persulfate aqueous solution B, with the dropping rate controlled at 0.25mL / min, wherein the mass ratio of mixed solution A, hydrolysate, ammonium persulfate aqueous solution A, acetone solution containing compound 1 and ammonium persulfate aqueous solution B is 8:1:2:0.4:2; continue the reaction for 2 hours after the addition is completed. The reaction temperature was maintained at 75℃ for h to obtain cationic polyacrylamide. The molecular weight of the cationic polyacrylamide was determined by Ubbelohde viscometer according to GB / T12005.1-1989 and GB / T12005.10-1992, and the molecular weight of the cationic polyacrylamide was found to be 13950.

[0031] (4) Prepare the cationic polyacrylamide obtained in step (3) and the glyoxal aqueous solution with a mass fraction of 40% at a mass ratio of 3.5:0.9, store them separately, and mix the cationic polyacrylamide and the glyoxal aqueous solution to react when used to obtain glyoxal-modified polyacrylamide.

[0032] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that 1,3-dimethoxy-1,3-dimethyl-1,3-divinyldisiloxane in step (2) is replaced with vinyltrimethoxysilane.

[0033] Comparative Example 2 Comparative Example 2 provides a method for synthesizing cationic polyacrylamide, comprising the following steps: (1) 1,3-Dimethoxy-1,3-dimethyl-1,3-divinyldisiloxane was added to a 75% ethanol aqueous solution according to a dosage ratio of 1g:9mL. The pH was adjusted to 3.8 using acetic acid and allowed to stand for 5.5h to complete the hydrolysis of silane and obtain the hydrolysate. (2) Add acrylamide and methacryloyloxyethyltrimethylammonium chloride to water, wherein the mass ratio of acrylamide to methacryloyloxyethyltrimethylammonium chloride is 11:2.5, and the ratio of acrylamide to water is 11g:55mL; to form a mixed solution; slowly add the mixed solution to the hydrolysate of step (2) at 0.75 mL / min, and simultaneously add 1.8 wt% ammonium persulfate aqueous solution A at 0.25 mL / min. After the addition is completed, continue the reaction for 1.5h, and maintain the reaction temperature at 72℃ to obtain cationic polyacrylamide; The molecular weight of cationic polyacrylamide was determined using an Ubbelohde viscometer according to GB / T12005.1-1989 and GB / T12005.10-1992, and the molecular weight of cationic polyacrylamide was found to be 12800.

[0034] (3) Prepare the cationic polyacrylamide obtained in step (2) and the 40% glyoxal aqueous solution at a mass ratio of 1.5:0.4, store them separately, and mix the cationic polyacrylamide and the glyoxal aqueous solution to react and obtain glyoxal modified polyacrylamide.

[0035] Experimental Example 1 The mixture B from step (3) of Example 1 and the cationic polyacrylamide obtained in Example 1 were freeze-dried to remove the monomers and solvents. Then, acetone was added for dissolution, and the mixture was pressed into a KBr pellet and tested using an infrared spectrometer. The results are as follows: Figure 1 As shown, curve a is the infrared curve of the product in mixture B of step (3), and curve b is the infrared curve of cationic polyacrylamide.

[0036] Depend on Figure 1 It can be seen that in curve a, 3223cm -1 3342cm -1 This is the characteristic peak of the stretching vibration of NH2 in the amide bond, at 1670 cm⁻¹. -1 The characteristic absorption peak of the carbonyl group appears at 1007 cm⁻¹. -1 The characteristic peak of Si-O-Si is 1418 cm⁻¹. -1 CH2N + The absorption peak of the methylene group of (CH3)3; compared with curve a, curve b shows an absorption peak at 1140 cm⁻¹. -1 1300cm -1 The characteristic peak of -SO2- appears at 1556 cm⁻¹. -1 The presence of a characteristic peak at C=N indicates that compound 1 successfully participated in the polymerization.

[0037] Experimental Example 2 The basis weight per sheet is 80g / m³ 3Weigh out softwood pulp, add deionized water at a pulp-to-water ratio of 9:1, and then add glyoxal-modified polyacrylamide obtained in Examples 1-3 and Comparative Examples 1-2 (the amount of glyoxal-modified polyacrylamide added is 3 wt% of the oven-dry weight of the softwood pulp). Place the above pulp into a decomposer to decompose it completely. After decomposition, add it into a paper forming machine to obtain standard paper with a paper sample of 2.8 g / sheet. Dry it in an oven at 100℃ for 10 min to obtain paper.

[0038] (1) Dry tensile strength index: Using a tensile strength tester, the paper to be tested is cut into a rectangle of 250mm×15mm according to the method of GB / T12914-2018. Each paper is measured 3 times and the average value is taken as the dry tensile strength index.

[0039] (2) Wet tensile strength index: The cut paper was immersed in deionized water for 10 minutes. After soaking, the paper was taken out and the surface moisture was wiped off with water. The tensile strength index was determined using a tensile strength tester according to the method of GB / T12914-2018. Each paper was measured 3 times and the average value was taken as the wet tensile strength index. The above test results are shown in Table 1.

[0040] Table 1 Group Dry tensile strength index (N•m / g) Wet tensile strength index (N•m / g) Example 1 95.8 21.2 Example 2 93.1 19.6 Example 3 94.5 20.3 Comparative Example 1 83.6 14.3 Comparative Example 2 91.4 17.7 As shown in Table 1, the paper obtained in Examples 1-3 of this invention exhibits excellent dry tensile strength and wet tensile strength indices. Compared with Example 1, Comparative Example 1 shows the worst dry and wet tensile strength indices, indicating that the glyoxal-modified polyacrylamide obtained in this invention has a significant impact on the strength of the paper.

[0041] Experimental Example 3 The glyoxal-modified polyacrylamide obtained in Examples 1-3 and Comparative Examples 1-2 was stored for 180 days. Then, paper was prepared according to the preparation method in Experimental Example 2, and the dry tensile strength index and wet tensile strength index were measured. The test results are shown in Table 2.

[0042] Based on the results in Tables 1 and 2, calculate the dry tensile strength retention rate and the wet tensile strength retention rate. Dry tensile strength change rate (%) = (dry tensile strength of the initial untreated sample - dry tensile strength index of the sample after 180 days of storage) / dry tensile strength of the initial untreated sample × 100%; The rate of change of wet tensile strength (%) = (wet tensile strength of the initial untreated sample - wet tensile strength index of the sample after 180 days of storage) / wet tensile strength of the initial untreated sample × 100%; the experimental results are shown in Table 3.

[0043] Table 2 Group Dry tensile strength index (N•m / g) Wet tensile strength index (N•m / g) Example 1 90.1 17.5 Example 2 85.7 15.8 Example 3 88.5 16.6 Comparative Example 1 75.5 11.2 Comparative Example 2 76.1 13.0 Table 3 Group Dry tensile strength change rate (%) Rate of change in wet tensile strength (%) Example 1 5.95 17.45 Example 2 7.95 19.39 Example 3 6.35 18.23 Comparative Example 1 9.69 21.68 Comparative Example 2 16.74 26.55 As shown in Tables 2 and 3, the tensile strength indices of Examples 1-3 of this invention are all higher than those before storage (180 days), indicating that the cationic modified polyacrylamide synthesized in this invention plays an important role in improving the tensile strength of paper. Compared with Example 1, the dry / wet tensile strength change rate is the largest after 180 days of storage, while the storage stability of Comparative Example 2 is poor, and the change rate of Comparative Example 1 is less than that of Comparative Example 2. The above results show that the cationic modified polyacrylamide synthesized in this invention has a dynamically stable three-dimensional network. This structure enables the product to exhibit excellent stability during storage, reduces transportation and packaging costs, allows for on-site production and use at the customer end, and is suitable for different customer scenarios, fundamentally solving the problems of short shelf life and unstable performance of traditional GPAM.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A method for synthesizing glyoxal-modified polyacrylamide, characterized in that, Includes the following steps: (1) Sulfamethidine and 4-vinylbenzaldehyde were added to a solvent and refluxed; the reaction solution was concentrated, filtered, recrystallized, and dried to obtain compound 1; (2) Add 1,3-dimethoxy-1,3-dimethyl-1,3-divinyldisiloxane to a solvent, and hydrolyze to obtain a hydrolysate; (3) Acrylamide and methacryloyloxyethyltrimethylammonium chloride are added to water to form a mixture A. Mixture A is added to the hydrolysate of step (2), and ammonium persulfate aqueous solution A is added to carry out the first reaction to obtain mixture B. Then, acetone solution containing compound 1 is added to mixture B, and ammonium persulfate aqueous solution B is added to carry out the second reaction to obtain cationic polyacrylamide. (4) Store the cationic polyacrylamide obtained in step (3) separately from glyoxal. When using, mix the cationic polyacrylamide and glyoxal to obtain glyoxal-modified polyacrylamide.

2. The method for synthesizing glyoxal-modified polyacrylamide according to claim 1, characterized in that, In step (1), the chemical structural formula of compound 1 is as follows: .

3. The method for synthesizing glyoxal-modified polyacrylamide according to claim 1, characterized in that, In step (1), the molar ratio of sulfadiazine to 4-vinylbenzaldehyde is 1:(1-1.1); the volume ratio of sulfadiazine to solvent is 2mol:3-5mL, and the solvent is acetone; the reflux time is 2-3h.

4. The method for synthesizing glyoxal-modified polyacrylamide according to claim 1, characterized in that, In step (2), the ratio of 1,3-dimethoxy-1,3-dimethyl-1,3-divinyldisiloxane to solvent is 1g:8-10mL; the solvent is an aqueous ethanol solution with a volume fraction of 70-80%; the pH during hydrolysis is 3.5-4, and the hydrolysis time is 5-6h.

5. The method for synthesizing glyoxal-modified polyacrylamide according to claim 1, characterized in that, In step (3), the mass ratio of acrylamide to methacryloyloxyethyltrimethylammonium chloride is (10-12):(2-3), and the ratio of acrylamide to water is 10-12g:50-60mL.

6. The method for synthesizing glyoxal-modified polyacrylamide according to claim 1, characterized in that, In step (3), the mass ratio of the mixture A, hydrolysate, ammonium persulfate aqueous solution A, acetone solution containing compound 1, and ammonium persulfate aqueous solution B is (6-8):1:(1-2):(0.3-0.4):(1-2); the concentration of the ammonium persulfate aqueous solution A is 1.5-2wt%; the temperature of the first reaction is 70-75℃ and the time is 1-2h; the concentration of the ammonium persulfate aqueous solution B is 1.5-2wt%; the temperature of the second reaction is 70-75℃ and the time is 2-3h; the ratio of the amount of compound 1 to acetone in the acetone solution containing compound 1 is 2-3g:3-4mL.

7. The method for synthesizing glyoxal-modified polyacrylamide according to claim 1, characterized in that, The rate of addition of mixture A is 0.7-0.8 mL / min; the rates of addition of ammonium persulfate aqueous solution A and ammonium persulfate aqueous solution B are both 0.2-0.25 mL / min.

8. The method for synthesizing glyoxal-modified polyacrylamide according to claim 1, characterized in that, In step (4), the mass ratio of cationic polyacrylamide to glyoxal is (1.5-3.5):(0.1-0.9), and the glyoxal is a 40% glyoxal aqueous solution.

9. The method for synthesizing glyoxal-modified polyacrylamide according to claim 1, characterized in that, The molecular weight of the cationic polyacrylamide is 13,000-100,000.

10. A glyoxal-modified polyacrylamide, characterized in that, Prepared by the synthesis method according to any one of claims 1-9.

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