A polyvinyl alcohol-modified multifunctional powder slump retainer and its preparation method

Abstract

This invention discloses a polyvinyl alcohol-modified multifunctional powder slump retainer and its preparation method. The preparation method is as follows: First, polyvinyl alcohol is etherified with p-halogenated benzoic acid to prepare a carboxyl-containing intermediate; second, the carboxyl-containing intermediate is amidated with an amino-terminated modified polyether to prepare a long-side-chain intermediate; then, the long-side-chain intermediate is activated by ortho-C-H oxidation with benzamide, and then coupled with a functional alkyne to form a ring to construct a functional group, thus preparing the target slump retainer; finally, the slump retainer is sliced ​​and pulverized using a slicer and a pulverizer, respectively, to obtain the powder slump retainer. This method uses widely available raw materials, and the preparation process is simple and safe; the product has a long shelf life; the product contains no anti-caking agents and other components, and has a fast dissolution rate, which can significantly reduce transportation costs; the product also has advantages such as antibacterial properties, reduced concrete shrinkage in the later stages, and high water retention; and the product has stable performance and can be stored for a long time.

Description

Technical Field

[0001] This invention relates to the field of admixtures for cement concrete, specifically to a polyvinyl alcohol-modified multifunctional powder slump retainer and its preparation method. Background Technology

[0002] Third-generation concrete water-reducing agents, such as polycarboxylate superplasticizers, can meet diverse construction needs by adjusting appropriate molecular weight, side chain length and density, and the proportion of different monomers, and have become the mainstream concrete admixtures on the market today. Most existing polycarboxylate admixtures on the market are 10%–50% water-based formulations, with solid admixtures primarily used in dry-mix mortars, grouting materials, and to reduce the high costs associated with long-distance transportation. As on-site application requirements become increasingly refined, the research and development and promotion of high-performance powder slump retainers are becoming more meaningful.

[0003] Currently, solid water-reducing agents are mainly obtained through bulk polymerization and drying dehydration. However, bulk polymerization systems have disadvantages such as high monomer concentration, high viscosity, poor material uniformity, and difficulty in heat dissipation. Active ends are easily embedded, double bonds are easily destroyed at high temperatures, macromonomer conversion rate is low, and problems such as acrylic acid self-polymerization are very likely to occur. Therefore, the industrialization of large-scale preparation of solid polycarboxylate superplasticizers by bulk polymerization has not yet been realized.

[0004] Patent publication number CN107987229A discloses a slump-preserving high-performance solid polycarboxylate superplasticizer, its preparation method, and its uses. This invention employs bulk polymerization, without using any solvents or media throughout the process, and the reaction is carried out at room temperature, overcoming the shortcomings of previous solid polycarboxylate synthesis processes that required high-temperature melting and polymerization. However, the exothermic reaction during the bulk polymerization process of this system is difficult to control, easily leading to problems such as high viscosity and monomer self-polymerization in the later stages. Patent publication number CN111533852A discloses a solid polycarboxylate superplasticizer and its preparation method. This method mainly involves adding a non-reactive solubilizer to the system to reduce the viscosity of the reaction system and increase the uniformity of mixing between materials. However, the addition of the non-reactive solubilizer also reduces the effective components of the entire system and cannot fundamentally solve the problems of high viscosity, small monomer self-polymerization, and high exothermic reaction in the later stages of bulk polymerization. Patent publication number CN111362613A discloses a solid polycarboxylate slump retainer and its preparation method. The method involves modifying the monomer and then heating it for bulk polymerization. The prepared powder slump retainer has good slump retention and viscosity reduction effects.

[0005] Besides bulk polymerization, spray drying is also a commonly used method for preparing solid water-reducing agents. Spray drying mainly involves rapidly drying water-based water-reducing agents into powder by passing a heated airflow. This method is energy-intensive and requires the addition of anti-caking agents to prevent the powder from sticking together during the spraying process. Because the powdered water-reducing agent obtained by this method has poor water solubility and significant loss of effective components, its overall performance is inferior to that of the water-based agent before powdering. For example, patent publication number CN111362615A discloses a powdered shrinkage-reducing polycarboxylate water-reducing agent and its preparation method, and patent publication number CN109535340A discloses a powdered early-strength polycarboxylate water-reducing agent and its preparation method. These inventions exhibit good flowability in gelation systems, are not prone to clumping, and have good storage stability. However, to ensure that the particles do not agglomerate, calcium-magnesium expanding agents and nano-expanding agents are added as separating agents, which reduces the effective components in the water-reducing agent and affects its performance.

[0006] Furthermore, patent publication number CN107739424A discloses a solid slump-retaining polycarboxylate superplasticizer and its preparation method. This method uses 1-8% water as a solvent. While this reduces the system viscosity to some extent during the reaction, the introduction of water causes the finished solid superplasticizer to easily form clumps, making it difficult to use and store. Patent publication number CN114685799A discloses a solid corrosion-inhibiting polycarboxylate superplasticizer and its preparation method, which involves grafting a main chain containing adsorption groups, followed by slicing to obtain the finished product. This method operates under mild conditions, requires no spray drying, and has low energy consumption. Summary of the Invention

[0007] 1. The technical problem to be solved:

[0008] To address the aforementioned technical problems, this invention provides a polyvinyl alcohol-modified multifunctional powder slump retainer and its preparation method. It directly modifies polyvinyl alcohol, which has excellent water retention properties, using it as the raw material. Compared to bulk polymerization, this preparation process overcomes the problem of high exothermic reaction during polymerization, resulting in high raw material utilization. Compared to dehydration methods such as spray drying, this invention eliminates the need for additional anti-caking agents, ensuring nearly 100% effective components and extremely high dissolution rates. This invention introduces rigid groups into the slump retainer, reducing the surface tension of water in concrete and decreasing the shrinkage force from water evaporation, thus achieving crack resistance and shrinkage reduction. Furthermore, the introduction of isoquinoline ketone achieves self-antibacterial properties. Therefore, this powder slump retainer, which exhibits good slump retention, a safe and simple production process, and excellent water retention, crack resistance, shrinkage reduction, and self-antibacterial functions, has considerable application prospects.

[0009] 2. Technical Solution:

[0010] A polyvinyl alcohol-modified multifunctional powder slump retainer, characterized in that: the powder slump retainer has the following structure:

[0011]

[0012] Wherein, the degrees of polymerization x, y, and n are each independently 1–200; R1 and R2 are combinations of one or more of the following: H, alkyl groups containing 1–10 carbon atoms, hydroxyalkyl groups containing 1–10 carbon atoms, carboxyl groups containing 1–10 carbon atoms, ester groups containing 1–10 carbon atoms, phenyl groups, or phenyl derivatives, and at least one of R1 and R2 is an ester group containing 1–10 carbon atoms; R3 is O or O-(CH2). z One or a combination of two of them, where z is 1 to 10.

[0013] A method for preparing a polyvinyl alcohol-modified multifunctional powder slump retainer includes the following steps:

[0014] Step 1: Polyvinyl alcohol and p-halogenated benzoic acid are added to solvent 1, and in the molten state, an acid-binding agent 1 is used to carry out a Williamson etherification reaction to prepare a carboxyl-containing intermediate;

[0015] Step 2: At a temperature of 60–120°C, the carboxyl-containing intermediate and the amino-terminated modified polyether are amidated under negative pressure using catalyst 1 to prepare a long side-chain intermediate. Then, at a temperature of 40–130°C, the long side-chain intermediate is mixed with an alkyne containing a functional group, solvent 2 is added, and the mixture is coupled with catalyst 2, acid-binding agent 2 and oxidant for 4–20 h to form a ring and construct a functional group, thus preparing the target slump retainer.

[0016] Step 3: After the reaction is complete, slice the flakes using a slicer, and then pulverize the flake slump retainer using a pulverizer to obtain a powder slump retainer.

[0017] Furthermore, the polyvinyl alcohol has a molecular weight of 1000-50000 and a degree of alcoholysis greater than 50%; the p-halogenated benzoic acid is any one or a combination of p-fluorobenzoic acid, p-chlorobenzoic acid, p-bromobenzoic acid, p-iodobenzoic acid, p-chloromethylbenzoic acid, and p-bromomethylbenzoic acid.

[0018] Further, solvent 1 is any one or a combination of acetonitrile, methanol, ethanol, tert-butanol, acetone, dichloromethane, chloroform, dimethyl sulfoxide, N,N-dimethylformamide, or 1,2-dichloroethane; acid-binding agent 1 is any one or a combination of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, disodium bicarbonate, dipotassium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, diethylamine, triethylamine, pyridine, 4-dimethylaminopyridine, and N,N'-dicyclohexylcarboimide.

[0019] Furthermore, the structure of the amino-terminated modified polyether is as follows:

[0020]

[0021] The degree of polymerization, n, ranges from 1 to 200.

[0022] Further, the catalyst 1 is any one or a combination of sulfuric acid, phosphoric acid, boric acid, p-toluenesulfonic acid, ferric sulfate, triethylbenzylammonium chloride, 4-dimethylaminopyridine, pyrrolylpyridine, N,N'-dicyclohexylcarboimide, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride.

[0023] Further, the alkyne containing the functional group is any one or a combination of propynic acid, 2-butynic acid, 2-pentynic acid, 2-heptynic acid, 2-octynic acid, 3-butynic acid, 4-pentynic acid, 5-hexynic acid, 6-heptynic acid, 7-octynic acid, 8-nonynic acid, phenylpropynic acid, methyl propynate, ethyl propynate, methyl 2-butynate, ethyl 2-butynate, methyl 3-butynate, ethyl 2-pentynate, methyl 4-pentynate, tert-butyl propynate, methyl heptynecarboxylic acid, methyl phenylpropynate, ethyl phenylpropynate, tert-butyl 4-pentynate, 2-hydroxy-3-butynic acid, 4-hydroxybut-2-alkynic acid, and ethyl 2-hydroxy-3-butynate.

[0024] Furthermore, the solvent 2 is any one or a combination of 2,2,2-trifluoroethanol, N,N-dimethylformamide, acetone, tert-butanol, tert-amyl alcohol, dimethyl sulfoxide, dioxane, p-xylene, and 1,2-dichloroethane.

[0025] Furthermore, the catalyst 2 is any one or a combination of ferric chloride, ferrous chloride, ferric oxide, copper chloride, cobalt acetate tetrahydrate, cobalt acetylacetonate, manganese acetate, manganese pentacarbonyl bromide, and nickel dibromide [1,2-bis(diphenylphosphine)ethane].

[0026] Furthermore, the acid-binding agent 2 is any one or a combination of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, disodium bicarbonate, dipotassium bicarbonate, sodium oxalate, cesium carbonate, sodium pentanoate and their hydrates; the oxidizing agent is any one or a combination of oxygen, silver oxide, silver acetate, silver carbonate, copper acetate and its hydrates, hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, and manganese acetate.

[0027] 3. Beneficial effects:

[0028] (1) In this scheme, polyvinyl alcohol with excellent water retention properties is used as the raw material for modification. Compared with bulk polymerization, the entire preparation process overcomes the problem of high exothermic reaction during polymerization and has a high raw material utilization rate. Moreover, polyvinyl alcohol is widely available, inexpensive, and has a wide range of molecular weights to choose from. The slump retainer prepared from it retains the good water retention properties of polyvinyl alcohol itself.

[0029] (2) The slump retainer prepared in this invention exhibits good slump retention in alkaline cementitious materials by releasing carboxyl groups through ester hydrolysis. By imparting a rigid hydrophobic benzene structure, it reduces the surface tension of water in concrete and decreases the shrinkage force caused by water evaporation, thereby solving the problem of later-stage concrete shrinkage. Furthermore, by imparting an isoquinoline ketone structure with excellent antibacterial properties, it endows the water-reducing agent with self-antibacterial and anti-corrosion capabilities.

[0030] (3) The powder slump retainer prepared by the present invention is different from the common spray drying process in the market. It has low energy consumption, no anti-caking agent and other components, and has the characteristics of fast dissolution speed. It can also greatly reduce transportation costs for long-distance transportation.

[0031] (4) The powder slump retainer prepared by the present invention is different from the bulk polymerization process. It has no polymerization step, thus avoiding problems such as high system viscosity, large heat release and slow heat dissipation, small monomer self-polymerization and low conversion rate of large monomer.

[0032] (5) The powder slump retainer prepared by the present invention can be stored stably at high temperature for a long time and is not prone to clumping.

[0033] Therefore, the powder slump retainer prepared using this method can solve the problems of low conversion rate, high energy consumption, and low powder formation efficiency in the preparation process of existing powder slump retainers. On the other hand, it can solve the problems of slow dissolution rate, low content of effective components, and single use effect in the use of existing powder slump retainers. It has the advantages of simple preparation process, wide availability of raw materials, and multiple functions. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the embodiments.

[0035] Example 1:

[0036] 0.01 mol polyvinyl alcohol (M n =7000, degree of alcoholysis 98%), 0.4 mol of p-chlorobenzoic acid and 5 mL of acetonitrile were added to a reaction vessel and heated to melt. A carboxyl-containing intermediate was prepared by Williamson etherification reaction using sodium hydroxide. At 80 °C, the carboxyl-containing intermediate was reacted with an amino-terminated modified polyether (M n=2000) under negative pressure, an amidation reaction was carried out with 0.1 g of sulfuric acid as a catalyst to prepare a long side-chain intermediate. Then, at 80 °C, the long side-chain intermediate was mixed with 0.2 mol of propynic acid and 0.2 mol of ethyl propynate, 5 mL of tert-amyl alcohol was added, and the mixture was reacted with 0.1 g of manganese acetate, 0.08 mol of sodium carbonate and 0.05 mol of copper acetate for 7 h to prepare the target slump retainer. After the reaction was completed, the mixture was sliced ​​and pulverized to obtain a polyvinyl alcohol modified multifunctional powder slump retainer.

[0037] The molecular structure is as follows:

[0038]

[0039] Where the degree of polymerization x1 and x2 are 20 and 20 respectively, then the degree of polymerization x = x1 + x2 = 20 + 20 = 40, and the degree of polymerization y and n are 120 and 44 respectively.

[0040] Example 2:

[0041] 0.01 mol polyvinyl alcohol (M n =10000, degree of alcoholysis 98%), 0.4 mol of p-bromobenzoic acid and 5 mL of dimethyl sulfoxide were added to a reaction vessel and heated to melt. A carboxyl-containing intermediate was prepared by Williamson etherification with sodium bicarbonate. At 90 °C, the carboxyl-containing intermediate was reacted with an amino-terminated modified polyether (M n =1500) under negative pressure, a long-side-chain intermediate was prepared by amidation reaction catalyzed by 0.1 g of phosphoric acid. Then, at 90 °C, the long-side-chain intermediate was mixed with 0.1 mol of 2-butynic acid and 0.3 mol of methyl 2-butynic acid, and 5 mL of 2,2,2-trifluoroethanol was added. The mixture was then reacted with 0.1 g of cobalt acetylacetone, 0.08 mol of sodium bicarbonate and 0.05 mol of silver acetate for 6 h to prepare the target slump retainer. After the reaction, the mixture was sliced ​​and pulverized to obtain a polyvinyl alcohol modified multifunctional powder slump retainer.

[0042] The molecular structure is as follows:

[0043]

[0044] Where the degree of polymerization x1 and x2 are 10 and 30 respectively, then the degree of polymerization x = x1 + x2 = 10 + 30 = 40, and the degree of polymerization y and n are 187 and 33 respectively.

[0045] Example 3:

[0046] 0.01 mol polyvinyl alcohol (M n=6000, degree of alcoholysis 98%), 0.45 mol of p-chloromethylbenzoic acid and 5 mL of N,N-dimethylformamide were added to a reaction vessel and heated to melt. A carboxyl-containing intermediate was prepared by Williamson etherification reaction using potassium hydroxide. At 100 °C, the carboxyl-containing intermediate was reacted with an amino-terminated modified polyether (M n =3000) Under negative pressure, a long-side-chain intermediate was prepared by amidation reaction catalyzed by 0.1 g of p-toluenesulfonic acid. Then, at 90 °C, the long-side-chain intermediate was mixed with 0.45 mol of 2-butynedoate ethyl ester, and 5 mL of N,N-dimethylformamide was added. The mixture was then reacted with 0.1 g of copper chloride, 0.08 mol of potassium bicarbonate and 0.05 mol of silver oxide for 6 h to prepare the target slump retainer. After the reaction, the mixture was sliced ​​and pulverized to obtain a polyvinyl alcohol modified multifunctional powder slump retainer.

[0047] The molecular structure is as follows:

[0048]

[0049] The degree of aggregation x, y and n are 45, 91 and 67, respectively.

[0050] Example 4:

[0051] 0.01 mol polyvinyl alcohol (M n =11000, degree of alcoholysis 98%), 0.4 mol of p-bromobenzoic acid and 5 mL of acetonitrile were added to a reaction vessel and heated to melt. A carboxyl-containing intermediate was prepared by Williamson etherification reaction using sodium hydroxide. At 100 °C, the carboxyl-containing intermediate was reacted with an amino-terminated modified polyether (M n =1000) Under negative pressure, an amidation reaction catalyzed by 0.1 g of sulfuric acid was carried out to prepare a long side-chain intermediate. Then, at 100 °C, the long side-chain intermediate was mixed with 0.2 mol of methyl propynate and 0.2 mol of methyl phenyl propynate, and 5 mL of dimethyl sulfoxide was added. The mixture was then reacted with 0.1 g of copper chloride, 0.08 mol of sodium oxalate and 0.05 mol of potassium persulfate for 10 h to prepare the target slump retainer. After the reaction was completed, the mixture was sliced ​​and pulverized to obtain a polyvinyl alcohol modified multifunctional powder slump retainer.

[0052] The molecular structure is as follows:

[0053]

[0054] Where the degree of polymerization x1 and x2 are 20 and 20 respectively, then the degree of polymerization x = x1 + x2 = 20 + 20 = 40, and the degree of polymerization y and n are 210 and 22 respectively.

[0055] Example 5:

[0056] 0.01 mol polyvinyl alcohol (Mn =8000, degree of alcoholysis 98%), 0.48 mol of p-bromomethylbenzoic acid and 5 mL of 1,2-dichloroethane were added to a reaction vessel and heated to melt. A carboxyl-containing intermediate was prepared by Williamson etherification reaction with calcium hydroxide. At 90 °C, the carboxyl-containing intermediate was reacted with an amino-terminated modified polyether (M n =1500) under negative pressure, a long-side-chain intermediate was prepared by amidation reaction catalyzed by 0.1 g sulfuric acid. Then, at 90 °C, the long-side-chain intermediate was mixed with 0.2 mol 2-pentyneic acid and 0.28 mol ethyl 2-pentyneic acid, 5 mL tert-amyl alcohol was added, and the mixture was reacted with 0.1 g ferric chloride, 0.08 mol sodium bicarbonate and 0.05 mol ammonium persulfate for 8 h to prepare the target slump retainer. After the reaction, the mixture was sliced ​​and pulverized to obtain a polyvinyl alcohol modified multifunctional powder slump retainer.

[0057] The molecular structure is as follows:

[0058]

[0059] Where the degree of polymerization x1 and x2 are 20 and 28 respectively, then the degree of polymerization x = x = x1 + x2 = 20 + 28 = 48; the degree of polymerization y and n are 134 and 33 respectively.

[0060] Example 6:

[0061] 0.01 mol polyvinyl alcohol (M n =9000, degree of alcoholysis 98%), 0.35 mol of p-bromobenzoic acid and 5 mL of acetonitrile were added to a reaction vessel and heated to melt. A carboxyl-containing intermediate was prepared by Williamson etherification reaction using potassium hydroxide. At 100 °C, the carboxyl-containing intermediate was reacted with an amino-terminated modified polyether (M n =1500) Under negative pressure, a long-side-chain intermediate was prepared by amidation reaction catalyzed by 0.1 g of p-toluenesulfonic acid. Then, at 100 °C, the long-side-chain intermediate was mixed with 0.35 mol of tert-butyl 4-pentyneate, and 5 mL of 2,2,2-trifluoroethanol was added. The mixture was then reacted with 0.1 g of cobalt acetylacetone, 0.08 mol of potassium carbonate, and 0.05 mol of silver oxide for 7 h to prepare the target slump retainer. After the reaction, the mixture was sliced ​​and pulverized to obtain a polyvinyl alcohol modified multifunctional powder slump retainer.

[0062] The molecular structure is as follows:

[0063]

[0064] The degree of aggregation x, y and n are 35, 170 and 33, respectively.

[0065] Example 7:

[0066] 0.01 mol polyvinyl alcohol (M n =10000, degree of alcoholysis 98%), 0.5 mol of p-chlorobenzoic acid and 5 mL of N,N-dimethylformamide were added to a reaction vessel and heated to melt. A carboxyl-containing intermediate was prepared by Williamson etherification reaction using potassium bicarbonate. At 70 °C, the carboxyl-containing intermediate was reacted with an amino-terminated modified polyether (M n =1000) under negative pressure, an amidation reaction was carried out with 0.1 g of sulfuric acid as a catalyst to prepare a long side-chain intermediate. Then, at 80 °C, the long side-chain intermediate was mixed with 0.1 mol of phenylpropynic acid and 0.4 mol of methyl propynate, and 5 mL of dioxane was added. The mixture was then reacted with 0.1 g of cobalt acetate tetrahydrate, 0.08 mol of disodium bicarbonate and 0.05 mol of silver carbonate for 5 h to prepare the target slump retainer. After the reaction, the mixture was sliced ​​and pulverized to obtain a polyvinyl alcohol modified multifunctional powder slump retainer.

[0067] The molecular structure is as follows:

[0068]

[0069] Where the degree of polymerization x1 and x2 are 10 and 40 respectively, then the degree of polymerization x = x1 + x2 = 10 + 40 = 50, and the degree of polymerization y and n are 177 and 22 respectively.

[0070] Example 8:

[0071] 0.01 mol polyvinyl alcohol (M n =5000, degree of alcoholysis 98%), 0.42 mol of p-bromobenzoic acid and 5 mL of dimethyl sulfoxide were added to a reaction vessel and heated to melt. A carboxyl-containing intermediate was prepared by Williamson etherification reaction using sodium hydroxide. At 70 °C, the carboxyl-containing intermediate was reacted with an amino-terminated modified polyether (M n =3000) under negative pressure, a long-side-chain intermediate was prepared by amidation reaction catalyzed by 0.1 g of phosphoric acid. Then, at 70 °C, the long-side-chain intermediate was mixed with 0.12 mol of 2-heptanynic acid and 0.3 mol of ethyl 2-butynylate, and 5 mL of 2,2,2-trifluoroethanol was added. The mixture was then reacted with 0.1 g of copper chloride, 0.08 mol of sodium oxalate and 0.05 mol of sodium persulfate for 7 h to prepare the target slump retainer. After the reaction, the mixture was sliced ​​and pulverized to obtain a polyvinyl alcohol modified multifunctional powder slump retainer.

[0072] The molecular structure is as follows:

[0073]

[0074] Where the degree of polymerization x1 and x2 are 12 and 30 respectively, then the degree of polymerization x = x1 + x2 = 12 + 30 = 32, and the degree of polymerization y and n are 72 and 67 respectively.

[0075] Test example:

[0076] 1. Cement paste fluidity test

[0077] Referring to GB / T 8077-2012 "Test Method for Homogeneity of Concrete Admixtures", the samples obtained in Examples 1 to 8 were compared with commercially available powder slump retainers (Comparative Examples 1 and 2) for paste fluidity testing. The results are shown in Table 1. The W / C ratio was 0.29, and the admixture dosage was 0.15% of the cement weight. Initial paste fluidity (after mixing) and fluidity over 1 to 4 hours were tested. The results showed that all examples exhibited significantly improved paste fluidity over time compared to the commercially available comparative examples, with virtually no loss after 4 hours.

[0078] Table 1. Flowability and loss over time of different samples of paste

[0079]

[0080] 2. Concrete performance testing

[0081] Referring to GB 8076-2008 "Concrete Admixtures", the samples obtained in Examples 1 to 8 were compared with commercially available powder slump retainers, Comparative Examples 1 and 2, to determine the initial slump / spread of concrete, slump / spread loss over 1 to 3 hours, concrete specimen strength, 28-day shrinkage ratio, cohesiveness, and water retention. The admixture dosage was 0.2% of the binder dosage. The specific results are shown in Table 2.

[0082] The results showed that, compared to the commercially available comparative example, the concrete in the embodiment exhibited higher slump and spread at different time points, demonstrating superior dispersion and dispersion retention performance. Furthermore, it was found that the concrete in the embodiment showed an average increase of 2.8 MPa in 3-day compressive strength, 2 MPa in 7-day compressive strength, and 2.2 MPa in 28-day compressive strength compared to the comparative example. The 28-day shrinkage rate of the concrete incorporating the embodiment of this invention was significantly lower than that of the commercially available comparative example. In addition, the embodiment showed significantly better cohesiveness and water retention compared to the comparative example.

[0083] Table 2. Slump retention and mechanical properties of concrete samples from different samples

[0084]

[0085] 3. Antibacterial performance test

[0086] Referring to JC / T 2552-2019 "Bactericides for Concrete Admixtures", the antifungal and bactericidal properties of the samples obtained in Examples 1 to 8, as well as commercially available Comparative Examples 1 and 2, were tested. In the tests, distilled water was added to the admixture until its solid content was diluted to 15%. Then, the same amount of microorganisms was injected into each group and stirred thoroughly. The mixtures were then placed in an incubator at 30±2℃ for cultivation. The presence of mold, mycelium, or off-odors was observed. The results are shown in Table 3.

[0087] The results showed that all comparative examples developed mycelia and odor within 6 months, while Example 2 only started to show mycelia and odor after 12 months. The other examples did not show mycelia or odor after 12 months. In other words, all examples demonstrated good self-antibacterial ability.

[0088] Table 3 Antibacterial properties of different samples

[0089]

[0090]

[0091] Although the present invention has been disclosed above with reference to preferred embodiments, these are not intended to limit the invention. Any person skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be defined by the scope of the claims of this application.

Claims

1. A polyvinyl alcohol-modified multifunctional powder slump retainer, characterized in that: Powder slump retainer has the following structure: ； Wherein, the degrees of polymerization x, y, and n are each independently 1 to 200; R1 and R2 are combinations of one or more of the following: H, alkyl groups containing 1 to 10 carbon atoms, hydroxyalkyl groups containing 1 to 10 carbon atoms, carboxyl groups containing 1 to 10 carbon atoms, ester groups containing 1 to 10 carbon atoms, phenyl groups, or phenyl derivatives, and at least one of R1 and R2 is an ester group containing 1 to 10 carbon atoms; R3 is O or O-(CH2). z One or a combination of two of them, where z is 1 to 10.

2. A method for preparing a polyvinyl alcohol-modified multifunctional powder slump retainer, used to prepare the powder slump retainer as described in claim 1, characterized in that: Includes the following steps: Step 1: Polyvinyl alcohol and p-halogenated benzoic acid are added to solvent 1, and in the molten state, an acid-binding agent 1 is used to carry out a Williamson etherification reaction to prepare a carboxyl-containing intermediate; Step 2: At a temperature of 60~120℃, the carboxyl-containing intermediate and the amino-terminated modified polyether are amidated under negative pressure using catalyst 1 to prepare a long side-chain intermediate. Then, at a temperature of 40~130℃, the long side-chain intermediate is mixed with an alkyne containing a functional group, solvent 2 is added, and the mixture is coupled and cyclized using catalyst 2, acid-binding agent 2 and oxidant for 4~20 h to construct the functional group and prepare the target slump retainer. Step 3: After the reaction is complete, slice the flakes using a slicer, and then pulverize the flake slump retainer using a pulverizer to obtain a powder slump retainer.

3. The preparation method of a polyvinyl alcohol modified multifunctional powder slump retainer according to claim 2, characterized in that: The polyvinyl alcohol has a molecular weight of 1000~50000 and a degree of alcoholysis greater than 50%; the p-halogenated benzoic acid is any one or a combination of p-fluorobenzoic acid, p-chlorobenzoic acid, p-bromobenzoic acid, p-iodobenzoic acid, p-chloromethylbenzoic acid, and p-bromomethylbenzoic acid.

4. The preparation method of a polyvinyl alcohol modified multifunctional powder slump retainer according to claim 2, characterized in that: Solvent 1 is any one or a combination of acetonitrile, methanol, ethanol, tert-butanol, acetone, dichloromethane, chloroform, dimethyl sulfoxide, N,N-dimethylformamide, or 1,2-dichloroethane; acid-binding agent 1 is any one or a combination of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, lithium hydroxide, diethylamine, triethylamine, pyridine, 4-dimethylaminopyridine, and N,N'-dicyclohexylcarboimide.

5. The preparation method of a polyvinyl alcohol modified multifunctional powder slump retainer according to claim 2, characterized in that: The structure of the amino-terminated modified polyether is as follows: ； The degree of polymerization, n, ranges from 1 to 200.

6. The preparation method of a polyvinyl alcohol modified multifunctional powder slump retainer according to claim 2, characterized in that: The catalyst 1 is any one or a combination of sulfuric acid, phosphoric acid, boric acid, p-toluenesulfonic acid, ferric sulfate, triethylbenzylammonium chloride, 4-dimethylaminopyridine, pyrrolylpyridine, N,N'-dicyclohexylcarboimide, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride.

7. The preparation method of a polyvinyl alcohol modified multifunctional powder slump retainer according to claim 2, characterized in that: The alkyne containing the functional group is any one or a combination of propynic acid, 2-butynic acid, 2-pentynic acid, 2-heptenynic acid, 2-octynic acid, 3-butynic acid, 4-pentynic acid, 5-hexynic acid, 6-heptenynic acid, 7-octynic acid, 8-nonynic acid, phenylpropynic acid, methyl propynate, ethyl propynate, methyl 2-butynate, ethyl 2-butynate, methyl 3-butynate, ethyl 2-pentynate, methyl 4-pentynate, tert-butyl propynate, methyl heptenynate, methyl phenylpropynate, ethyl phenylpropynate, tert-butyl 4-pentynate, 2-hydroxy-3-butynic acid, 4-hydroxybut-2-alkynic acid, and ethyl 2-hydroxy-3-butynate.

8. The preparation method of a polyvinyl alcohol modified multifunctional powder slump retainer according to claim 2, characterized in that: The solvent 2 is any one or a combination of 2,2,2-trifluoroethanol, N,N-dimethylformamide, acetone, tert-butanol, tert-amyl alcohol, dimethyl sulfoxide, dioxane, p-xylene, and 1,2-dichloroethane.

9. The preparation method of a polyvinyl alcohol modified multifunctional powder slump retainer according to claim 2, characterized in that: The catalyst 2 is any one or a combination of ferric chloride, ferrous chloride, ferric oxide, copper chloride, cobalt acetate tetrahydrate, cobalt acetylacetonate, manganese acetate, manganese pentacarbonyl bromide, and nickel dibromide [1,2-bis(diphenylphosphine)ethane].

10. The preparation method of a polyvinyl alcohol modified multifunctional powder slump retainer according to claim 2, characterized in that: The acid-binding agent 2 is any one or a combination of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium oxalate, cesium carbonate, sodium pentanoate and their hydrates; the oxidizing agent is any one or a combination of oxygen, silver oxide, silver acetate, silver carbonate, copper acetate and its hydrates, hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, and manganese acetate.

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