Environment-friendly self-preservative polycarboxylate superplasticizer, preparation method and application thereof

Abstract

The application provides an environment-friendly self-preservative polycarboxylic acid water reducing agent and a preparation method and application thereof.The water reducing agent is prepared by free radical copolymerization of 100 parts of polyether macromonomer, 10-15 parts of unsaturated carboxylic acid and derivatives thereof, 0.1-0.5 parts of quaternary ammonium salt functional monomer, 0.05-0.25 parts of imidazole ring containing unsaturated monomer, 0.3-0.9 parts of performance compensation monomer, an initiator and water by weight. The quaternary ammonium salt and imidazole ring double-effect bacteriostatic groups are covalently grafted on the main chain to realize the endogenesis of the preservative function, completely solve the pain point that the traditional external preservative is easy to degrade and invalid, and give the product long-acting and wide-spectrum bacteriostatic capacity. Meanwhile, the MPEGAc is innovatively introduced, the polar and long and short chain complementary effect is utilized, and the molecular chain curling caused by the cationic group and the water reducing performance loss are precisely compensated. The product has high water reducing rate, excellent slump retention and persistent self-preservative stability.

Description

Technical Field

[0001] This invention relates to the field of concrete admixtures, and particularly to an environmentally friendly, self-corroding polycarboxylate superplasticizer, its preparation method, and its application. Background Technology

[0002] Polycarboxylate superplasticizers, as core products of high-performance concrete admixtures, have been widely used in various infrastructure constructions due to their high water reduction rate, good slump retention, and excellent improvement on the mechanical properties of concrete. They have become key materials driving the development of concrete technology towards high strength, high durability, and self-leveling. However, most polycarboxylate superplasticizers are water-based systems. Their main components, polyether macromonomers, carboxylic acid monomers, and residual small molecules, provide ample carbon and nitrogen sources for microorganisms such as bacteria, molds, and yeasts, making them highly susceptible to microbial contamination problems.

[0003] During storage, transportation, and use, microbial growth can cause water-reducing agents to deteriorate, exhibiting phenomena such as mold growth, foul odor, pH decrease, and reduced water-reducing performance. This not only leads to product scrapping and economic losses but also affects the slump and workability of concrete, even reducing its mechanical properties and posing a serious threat to project quality. Currently, the mainstream approach in the industry to address this issue is to add additional preservatives, but this method has several significant drawbacks. Traditional preservatives (such as formaldehyde releasers and isothiazolinones) have insufficient compatibility with the molecular structures of polycarboxylate water-reducing agents, and some preservatives can damage the main chain structure of the water-reducing agent, resulting in decreased water-reducing and slump-holding performance. Furthermore, their anti-corrosion effect is often unstable. For example, isothiazolinone preservatives are prone to decomposition and failure in the high pH environment of concrete, making long-term corrosion protection difficult and posing a potential risk of corrosion to the reinforcing steel in the concrete. In addition, the additional addition process not only increases the complexity of the production process but also further increases the overall cost of the product due to the procurement of preservatives, thus increasing the production burden on enterprises.

[0004] To address the microbial contamination problem of polycarboxylate superplasticizers, existing technologies have undergone some exploration and optimization. For example, some studies have attempted to introduce a single quaternary ammonium salt group into the molecular structure of the superplasticizer to improve its antibacterial properties. However, the antibacterial spectrum of a single group is narrow, especially its inhibitory effect on molds is weak, and the introduction of such groups often sacrifices some of the superplasticizer's water-reducing properties. Another approach attempts to improve the preservative effect by compounding preservatives, but this method has not yet escaped the limitations of "physical compounding," and the compatibility and long-term stability issues between the preservative and superplasticizer system remain unresolved. In addition, some studies have attempted to introduce imidazole ring monomers, but the antibacterial activity of a single imidazole ring group is limited and cannot meet the practical requirements for long-term stable storage of industrial products.

[0005] In practical engineering applications, the aforementioned technical defects often lead to serious engineering and economic risks. Taking a large-scale water conservancy project in southwestern my country as an example, the polycarboxylate superplasticizer used in the project had poor compatibility between the added preservative and the original system. When stored in the high-temperature environment of summer, not only did the preservative fail, leading to the proliferation of microorganisms and product deterioration, but the negative impact of the preservative also caused the water reduction rate of the superplasticizer to drop sharply by 15%, ultimately resulting in direct economic losses of several million yuan and seriously delaying the construction progress.

[0006] In summary, overcoming the inherent drawbacks of insufficient antibacterial activity of single-function monomers and poor compatibility of traditional physical compounding methods, and developing a polycarboxylate superplasticizer that achieves integrated "water reduction and corrosion prevention" functions through the synergistic effect of specific functional monomers, while also possessing environmental friendliness and excellent workability, has become an urgent technical challenge that fully aligns with the green and functional development trend of the concrete admixture industry and has significant practical value. Summary of the Invention

[0007] To address the aforementioned technical problems, this application provides an environmentally friendly, self-corroding polycarboxylate superplasticizer, its preparation method, and its application.

[0008] In a first aspect, the present invention proposes an environmentally friendly, self-corroding polycarboxylate superplasticizer. The environmentally friendly, self-corroding polycarboxylate superplasticizer is based on 100 parts by weight of polyether macromonomer and includes the following polymer raw materials in parts by weight: 10-15 parts of unsaturated carboxylic acid and its derivatives, 0.1-0.5 parts of quaternary ammonium salt functional monomers, 0.05-0.25 parts of imidazole ring-containing unsaturated monomers, 0.3-0.9 parts of performance-compensating monomers, 0.5-1.5 parts of initiator, and 200-300 parts of water.

[0009] In the above technical solution, through the synergistic combination of polyether macromonomers, unsaturated carboxylic acids, dual-effect antibacterial monomers and performance-compensating monomers, the polymer is successfully endowed with long-lasting chemical endogenous anti-corrosion function without relying on physical external preservatives, while fundamentally overcoming the defect of deterioration in water-reducing performance caused by anti-corrosion modification.

[0010] Furthermore, the polymerization raw materials also include: 0.1 to 0.5 parts of chain transfer agent, 0.05 to 0.25 parts of reducing agent, and auxiliary raw materials, including 0.5 to 1.0 parts of sodium hypophosphite and 0.01 to 0.03 parts of ferrous sulfate. The polymerization raw materials also include liquid alkali for adjusting the pH value; wherein, the chain transfer agent is selected from one or more of mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptoethanol, or sodium methylpropenesulfonate; the reducing agent is selected from one or more of sodium bisulfite, vitamin C, ferrous sulfate, or glucose.

[0011] In the above technical solution, by introducing specific types of chain transfer agents, reducing agents and auxiliary raw materials, the reaction kinetics of free radical polymerization are effectively optimized, and the molecular weight and distribution width of the polymer backbone are precisely controlled, thereby ensuring the performance stability and excellent slump retention between product batches.

[0012] Furthermore, the number-average molecular weight of the polyether macromonomer is between 2900 and 3100 g / mol; the molecular formula of the polyether macromonomer is: CH2=C(CH3)CH2O(CH2CH2O). n H, where n is a positive integer.

[0013] In the above technical solution, a specific molecular weight of polyether macromonomer is defined, which provides the most suitable side chain length for the polymer, ensuring that it can form a stable and ideally thick three-dimensional hydration film on the surface of cement particles, thereby providing strong steric hindrance and repulsion to maintain excellent initial dispersibility.

[0014] Furthermore, the quaternary ammonium salt functional monomers are selected from one or more of acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloyloxypropyltrimethylammonium chloride, dimethyldiallylammonium chloride, and vinylbenzyltrimethylammonium chloride. The selected specific quaternary ammonium salt functional monomers, relying on their strong cationic properties, rapidly target and adsorb to disrupt the cell membrane structure of microorganisms, providing the water-reducing agent system with rapid-acting initial bactericidal and preservative capabilities.

[0015] Furthermore, the imidazole-containing unsaturated monomers are selected from one or more of 1-vinylimidazole, 2-methyl-1-vinylimidazole, 4-vinylimidazole, 1-allylimidazole, and 2-ethyl-1-vinylimidazole. The screened imidazole-containing unsaturated monomers possess unique nitrogen heterocyclic structures that can form a significant positive synergistic antibacterial effect with quaternary ammonium salt groups, effectively blocking the activity of intracellular enzymes in microorganisms and endowing the system with long-lasting and broad-spectrum antibacterial stability.

[0016] Furthermore, the performance-compensating monomer is polyethylene glycol monomethyl ether acrylate, with a number-average molecular weight selected from 400, 600, or 800; the grafting amount of the performance-compensating monomer is 0.5–0.9 parts. The preferred performance-compensating monomer, with its unique ester group polarity and moderate side chain length, can target and relieve the conformational coiling phenomenon of molecular chains caused by cationic groups, and through the complementary topological structure of long and short side chains, completely compensate for the steric hindrance loss caused by anti-corrosion modification.

[0017] Furthermore, the unsaturated carboxylic acids and their derivatives are selected from one or more of acrylic acid, acrylamide, methacrylic acid, maleic anhydride, methyl acrylate, dimethyl maleate, and 2-acrylamido-2-methylpropanesulfonic acid; the water is deionized water; and the initiator is selected from one or more of ammonium persulfate and potassium persulfate. The preferred types of main reactants are further defined, ensuring a reasonable distribution of carboxyl group density in the polymerization system, providing a sufficient initial electrostatic repulsion source for the water-reducing agent, and simultaneously guaranteeing the purity of the reaction system and the polymerization conversion rate.

[0018] Secondly, this invention proposes a method for preparing an environmentally friendly, self-corroding polycarboxylate superplasticizer as described in the first aspect, the method comprising:

[0019] S1, add the prescribed amount of water, polyether macromonomer, quaternary ammonium salt functional monomer, imidazole ring-containing unsaturated monomer, performance compensation monomer, and auxiliary raw materials into the reactor, and stir at room temperature until completely dissolved to obtain the prepared base material; S2, prepare an aqueous solution of unsaturated carboxylic acids and their derivatives, and prepare an aqueous solution of reducing agent and chain transfer agent; S3, after adding an initiator to the reactor to initiate the polymerization reaction, add aqueous solution one and aqueous solution two dropwise to the reactor simultaneously.

[0020] S4, after the addition is complete, keep the reaction at a constant temperature, allow it to cool naturally, and adjust the pH value to neutral to obtain the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor.

[0021] The above technical solution provides a simple, efficient, and low-energy-consumption room-temperature synthesis process. By scientifically planning the dropwise order of the substrate, initiator, and various aqueous solutions, explosive polymerization or cross-linking side reactions caused by excessively high local monomer concentrations are effectively avoided, ensuring the efficient graft copolymerization of each functional monomer.

[0022] Furthermore, in step S1, the temperature of the reactor is controlled at 25–30°C; in step S3, the mass fraction of aqueous solution one is 30%, and the dropwise addition time of aqueous solution one and aqueous solution two is 1.5–2 hours; in step S4, the reaction is carried out at room temperature for 1–2 hours, after which it is naturally cooled to room temperature, and liquid alkali is added to adjust the pH value to 6.5–7.5. This further refines the control of the thermodynamic and kinetic parameters of the polymerization process. By precisely matching the dropwise addition time and the holding temperature, a smooth transition of the exothermic reaction is achieved, maximizing the structural regularity and yield of the target comb-shaped polymer.

[0023] Thirdly, this invention proposes the environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer described in the first aspect and the preparation method of the environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer described in the second aspect, and its application in the preparation of building materials or concrete.

[0024] The above technical solution clarifies the end-use scenarios of this environmentally friendly, self-corrosion-resistant polycarboxylate superplasticizer. It not only improves the performance of downstream building materials and concrete engineering, but also effectively extends the safe storage period of the admixture in complex climatic environments, and has significant industrial practical value.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention introduces bifunctional monomers containing quaternary ammonium salts and imidazole rings, which are then grafted onto the polycarboxylic acid backbone in a stable covalent bond form. This fundamentally prevents the loss of effective preservative components due to release, migration, and degradation during storage, transportation, and complex application environments. Furthermore, these two functional groups form a strong positive synergistic effect at the microscopic level: the quaternary ammonium salt group preferentially disrupts the integrity of microbial cell membranes due to its strong cationic properties, while the imidazole ring group deeply inhibits the synthesis of microbial nucleic acids. This powerful combination exhibits excellent broad-spectrum inhibition and killing capabilities against various common spoilage microorganisms such as Escherichia coli, Aspergillus niger, and Staphylococcus aureus, with a 7-day inhibition rate consistently above 91%. Even after 60 days of natural storage at room temperature, the product remains free of mold and odor, completely eradicating the industry-wide problem of polycarboxylic acid superplasticizers easily developing mold and odor during long-term storage.

[0026] 2. This invention innovatively introduces polyethylene glycol monomethyl ether acrylate with a specific molecular weight as a performance-compensating monomer. This monomer effectively eliminates the electrostatic association of "internal salts" between positive and negative charges by providing precise short-chain steric hindrance compensation, optimizing and regularizing the comb-like topology of the polymer backbone. This not only allows the water-reducing agent to maintain excellent initial high water reduction rate and outstanding slump retention performance over time (water reduction rate retention rate is still above 95.1% after 60 days of storage) without the need for any additional preservatives, but also exhibits unexpected technical effects in macroscopic applications—its optimized molecular conformation significantly promotes the early and late hydration process of cement, greatly improving the compressive strength of the formed concrete.

[0027] 3. This invention employs a room-temperature aqueous solution free radical polymerization process, which is solvent-free, environmentally friendly, and easily mass-produced industrially. The resulting environmentally friendly, self-corroding polycarboxylate superplasticizer can be used alone or in combination with other superplasticizers, offering convenient and flexible application. With its superior "water reduction-slump retention-corrosion prevention" three-in-one performance, this product can be widely used in high-performance concrete for various infrastructure constructions such as bridges, high-rise buildings, and water conservancy projects. It is particularly suitable for harsh construction environments such as high temperature and high humidity, which easily induce rapid microbial growth. This invention not only perfectly addresses the demanding challenges of long-term storage and long-distance cross-regional transportation but also effectively ensures the absolute stability of the concrete's workability and macroscopic mechanical properties under complex working conditions, possessing extremely broad potential for large-scale commercialization. Attached Figure Description

[0028] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. Many anticipated advantages of the embodiments and other embodiments of the invention will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0029] Figure 1 This is a flowchart of a method for preparing an environmentally friendly, self-corrosion-resistant polycarboxylate superplasticizer according to an embodiment of the present invention. Detailed Implementation

[0030] In the following detailed description, reference is made to the accompanying drawings, which form part of the detailed description and are illustrated by way of illustrative specific embodiments in which the invention may be practiced. In this regard, directional terms such as “top,” “bottom,” “left,” “right,” “up,” “down,” etc., are used with reference to the orientation of the described figures. Because components of the embodiments may be positioned in several different orientations, directional terms are used for illustrative purposes and are by no means limiting.

[0031] It should be understood that other embodiments or logical changes may be made without departing from the scope of the invention. Therefore, the following detailed description should not be taken in a limiting sense, and the scope of the invention is defined by the appended claims.

[0032] It should be noted in advance that, unless otherwise specified, the molecular weights of the polymers and monomers mentioned in this article are exponential molecular weights.

[0033] Figure 1 A flowchart illustrating a method for preparing an environmentally friendly, self-corroding polycarboxylate superplasticizer according to an embodiment of this application is shown. Figure 1 As shown, the method includes the following steps: S1. Add the prescribed amounts of water, polyether macromonomer, quaternary ammonium salt functional monomer, imidazole ring-containing unsaturated monomer, performance compensation monomer, and auxiliary raw materials to the reactor and stir at room temperature until completely dissolved to obtain the prepared base material.

[0034] In some specific embodiments, based on 100 parts by weight of the polyether macromonomer, 200-300 parts of water, 100 parts of the polyether macromonomer, 0.1-0.5 parts of quaternary ammonium salt functional monomers, 0.05-0.25 parts of imidazole ring-containing unsaturated monomers, 0.3-0.9 parts of performance-compensating monomers, and auxiliary materials are added to a reaction vessel and stirred at room temperature until completely dissolved to obtain the prepared base material. The water is deionized water. The polyether macromonomer is preferably isopentenyl polyoxyethylene ether (GPEG), and more preferably, a polyether macromonomer with a number average molecular weight of 2900-3100 g / mol (commonly referred to in the industry as GPEG3000) is selected. The molecular formula of the polyether macromonomer is: CH2=C(CH3)CH2O(CH2CH2O). n H, where n is a positive integer; the quaternary ammonium salt functional monomer is selected from one or more of acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloyloxypropyltrimethylammonium chloride, dimethyldiallylammonium chloride and vinylbenzyltrimethylammonium chloride; the imidazole ring-containing unsaturated monomer is selected from one or more of 1-vinylimidazolium, 2-methyl-1-vinylimidazolium, 4-vinylimidazolium, 1-allylimidazolium and 2-ethyl-1-vinylimidazolium.

[0035] Specifically, in the preparation of the base material, deionized water, GPEG3000, sodium hypophosphite, liquid alkali, quaternary ammonium salt functional monomers, imidazole ring-containing unsaturated monomers, ferrous sulfate and performance compensation monomers are added to the reactor in sequence, and the electric stirrer is turned on to stir until completely dissolved, and the reaction temperature is controlled at room temperature (25-30℃).

[0036] Furthermore, the performance compensation monomer is preferably polyethylene glycol monomethyl ether acrylate (MPEGAc), with a number-average molecular weight selected from 400, 600 or 800, and preferably polyethylene glycol monomethyl ether acrylate with a molecular weight of 600 (often referred to in the industry as MPEGAc-600).

[0037] Through in-depth research, the inventors discovered that the grafting modification of quaternary ammonium salts with cationic antibacterial groups containing imidazole rings often leads to a decrease in the initial water reduction rate of polycarboxylate superplasticizers. The underlying mechanism can be attributed to three aspects: adsorption competition, molecular conformational shrinkage, and imbalance of polymerization activity. Specifically, the introduction of strong cationic groups into functional monomers readily leads to competitive preferential adsorption on the negative potential sites of cement particles, or strong electrostatic attraction with anionic carboxyl groups on the polycarboxylic acid backbone to form an "internal salt" structure. This significantly consumes and reduces the effective carboxyl adsorption amount that plays a core dispersing role. At the same time, the electrostatic association between the positive and negative charges causes severe "shrinkage" and entanglement in the conformation of comb-shaped polymer molecules, severely restricting the free extension of polyether side chains in space. This significantly weakens the steric hindrance effect, making it difficult to provide sufficient repulsive force to effectively disintegrate the flocculated structure in the early stage of cement hydration. Furthermore, from the perspective of polymer synthesis kinetics, the reactivity ratio of such large-volume cationic antibacterial monomers differs inherently from that of conventional backbone monomers. This easily disrupts the original active balance of the copolymerization system, resulting in extremely uneven distribution of carboxyl sequences on the backbone and an abnormally broad molecular weight distribution of the final product. Consequently, the proportion of effective polymer components with actual water-reducing and dispersing effects in the system is significantly reduced.

[0038] To systematically address the aforementioned challenges, this invention innovatively introduces MPEGAc as a performance compensation monomer to deeply and targetedly compensate for the water-reducing performance loss of the self-preservative water-reducing agent. Its mechanism is mainly reflected in three dimensions: polymerization structure optimization, spatial conformation uncoiling, and interfacial adsorption kinetics regulation. Firstly, from the perspective of polymerization reaction kinetics, MPEGAc exhibits an extremely excellent matching degree of polymerization ratio with the main comonomer acrylic acid (AA). The introduction of trace amounts of MPEGAc significantly regulates the sequence distribution of carboxyl groups on the main chain, increasing the charge density of effective adsorption groups to fully restore electrostatic repulsion. Simultaneously, it effectively inhibits the random branching side reactions caused by cationic antibacterial monomers, thereby narrowing the molecular weight distribution of the polymer and significantly increasing the proportion of effective water-reducing components in the system. Secondly, at the spatial conformation level, the specific polarity of the ester group in the MPEGAc molecule can effectively weaken and dissolve the electrostatic interaction of the "internal salt" that is easily formed between the cationic groups such as quaternary ammonium salt or imidazole ring and the anionic carboxyl groups of the main chain, causing the polymer main chain and side chains that were originally curled up due to the attraction of positive and negative charges to fully extend again. Furthermore, the short polyether side chains introduced by MPEGAc grafting and the inherent long polyether side chains of macromonomers form a perfect "long-short complementary" topology in space, which precisely fills the spatial gaps in the adsorption layer, greatly improving the density of the hydration film on the surface of cement particles, thereby rapidly and fully releasing the free water wrapped in the flocculation structure. Finally, regarding the adsorption kinetics at the solid-liquid interface, the incorporation of MPEGAc can significantly reduce the critical micelle concentration of the water-reducing agent macromolecules, enabling polymer molecules to rapidly reach adsorption saturation on the surface of cement particles within a shorter induction period. In addition, the weak hydrolysis characteristics of the ester groups in MPEGAc under alkaline microenvironment temporarily and locally increase the concentration of free carboxyl groups in the initial stage of hydration, thereby strongly offsetting and suppressing the competitive adsorption disadvantage brought by the cationic antibacterial groups, fundamentally ensuring and enhancing the initial dispersion efficiency and macroscopic water-reducing performance of the water-reducing agent system.

[0039] To demonstrate the practical effect of the aforementioned targeted compensation mechanism through specific experiments, this invention systematically investigated the directional regulatory effect of the specific performance compensation monomer MPEGAc on water-reducing performance. In the specific experimental design, the dosage of acryloyloxyethyltrimethylammonium chloride monomer was fixed at 0.3 parts and the dosage of 1-vinylimidazolium monomer was fixed at 0.15 parts as evaluation benchmarks. Three different molecular weight specifications of MPEGAc (i.e., MPEGAc-400, MPEGAc-600, and MPEGAc-800) were selected as performance adjustment variables, and their grafting dosage gradients were set to 0.3 parts, 0.5 parts, 0.7 parts, and 0.9 parts, respectively. The aim was to comprehensively examine the targeted compensation effect of MPEGAc with different molecular weights and dosage ratios on the macroscopic water-reducing performance of the system, thereby screening out the optimal side chain steric hindrance and adsorption charge balance scheme. The specific experimental evaluation data and test results are detailed in Table 1.

[0040] Table 1. Compensation effect of polyethylene glycol monomethyl ether acrylate on water-reducing performance.

[0041] As shown in Table 1, the introduction of the performance-compensating monomer MPEGAc has a highly significant targeted compensation effect on the water-reducing performance loss caused by the cationic antibacterial group, and this compensation effect is closely related to the molecular weight of the polyether side chain and the grafting amount. Specifically, under the condition of a fixed grafting amount of 0.5 parts, MPEGAc-600 with a molecular weight of 600 exhibits the best performance compensation effect, with an initial pulp flowability of 263 mm and a 1-hour pulp flowability of 242 mm, which is significantly better than the blank group without the addition of this compensating monomer (245 mm and 220 mm, respectively). This is because the molecular side chain length of MPEGAc-600 is moderate, and grafting it onto the polycarboxylic acid backbone can effectively enhance the steric hindrance effect of the polymer molecules, thereby fully dispersing cement particles and perfectly compensating for the negative impact of the strong adsorption characteristics of the antibacterial group on the water-reducing performance. In contrast, MPEGAc-400 has a relatively short polyether side chain, which provides a weak steric hindrance effect, resulting in an initial flowability of only 251 mm and a limited compensation effect. On the other hand, MPEGAc-800 has an excessively long molecular chain, which causes the steric hindrance of the large-volume monomer to hinder the copolymerization activity during the polymerization process, resulting in insufficient grafting rate and its initial flowability dropping back to 256 mm. Furthermore, gradient experiments on the optimal monomer MPEGAc-600 showed that when the grafting amount was set to 0.7 parts, the system's paste fluidity and slump retention performance reached the best global level, with the initial fluidity surging to 269 mm and the 1-hour fluidity reaching 250 mm. When the amount was less than 0.5 parts (such as the 0.3 part group), the space compensation effect was limited due to insufficient side link grafting density, and the initial fluidity was only 256 mm. When the amount exceeded 0.9 parts, the excessive and dense polyether long chains caused the macromolecular chains to become entangled, which slightly reduced the dispersion efficiency of the main chain at the solid-liquid interface, resulting in the initial fluidity dropping to 258 mm. Furthermore, examining the total bacterial count data of each test group, the groups with different molecular weights and dosages of MPEGAc consistently maintained a total bacterial count between 76 CFU / mL and 82 CFU / mL, showing no substantial difference compared to the 75 CFU / mL of the control group. This fully demonstrates that the introduction of this compensating monomer only plays a dispersive compensating role in physical conformation, without interfering with or weakening the chemical antibacterial efficacy of the bifunctional monomer. Based on the above data and mechanism verification, it can be precisely determined that the optimal specification of the performance compensating monomer in the system of this invention is MPEGAc-600, and its optimal grafting dosage is 0.7 parts.

[0042] S2, prepare an aqueous solution of unsaturated carboxylic acids and their derivatives, and prepare an aqueous solution of reducing agent and chain transfer agent.

[0043] In some specific embodiments, unsaturated carboxylic acids and their derivatives are prepared into a 30% (w / w) aqueous solution (I), and a reducing agent and a chain transfer agent are prepared into an aqueous solution (II) in a certain proportion. The unsaturated carboxylic acids and their derivatives are selected from one or more of acrylic acid, acrylamide, methacrylic acid, maleic anhydride, methyl acrylate, dimethyl maleate, and 2-acrylamido-2-methylpropanesulfonic acid; the chain transfer agent is selected from one or more of mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptoethanol, or sodium methacrylate sulfonate; and the reducing agent is selected from one or more of sodium bisulfite, vitamin C, ferrous sulfate, or glucose.

[0044] S3, after adding an initiator to the reactor to initiate the polymerization reaction, add aqueous solution one and aqueous solution two dropwise to the reactor simultaneously.

[0045] In some specific embodiments, an initiator is added to the reactor at once to initiate the polymerization reaction. Subsequently, solutions one and two are simultaneously added dropwise to the reactor using a peristaltic pump, with the addition time controlled to be 1.5–2 hours. The initiator is selected from one or more of ammonium persulfate and potassium persulfate.

[0046] S4, after the addition is complete, keep the reaction at a constant temperature, allow it to cool naturally, and adjust the pH value to neutral to obtain the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor.

[0047] In some specific embodiments, after the addition is complete, the mixture is kept at room temperature for 1-2 hours, then naturally cooled to room temperature. Liquid alkali is then added to adjust the pH to 6.5-7.5, thus obtaining the environmentally friendly self-preserving polycarboxylate superplasticizer mother liquor. The liquid alkali is selected from at least one of sodium hydroxide solution or potassium hydroxide solution.

[0048] The environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer finally obtained by the above preparation method is based on 100 parts by weight of polyether macromonomer, and includes the following other polymer raw materials by weight: 10-15 parts of unsaturated carboxylic acid and its derivatives, 0.1-0.5 parts of quaternary ammonium salt functional monomers, 0.05-0.25 parts of imidazole ring-containing unsaturated monomers, 0.3-0.9 parts of performance compensation monomers, 0.5-1.5 parts of initiator, and 200-300 parts of water.

[0049] In some specific embodiments, the polymerization raw materials also include: 0.1 to 0.5 parts of chain transfer agent, 0.05 to 0.25 parts of reducing agent, and auxiliary raw materials, including 0.5 to 1.0 parts of sodium hypophosphite and 0.01 to 0.03 parts of ferrous sulfate. The polymerization raw materials also include liquid alkali for adjusting the pH value.

[0050] In some specific embodiments, the number-average molecular weight of the polyether macromonomer is between 2900 and 3100 g / mol; the molecular formula of the polyether macromonomer is: CH2=C(CH3)CH2O(CH2CH2O). n H, where n is a positive integer. The unsaturated carboxylic acid and its derivatives are selected from one or more of acrylic acid, acrylamide, methacrylic acid, maleic anhydride, methyl acrylate, dimethyl maleate, and 2-acrylamido-2-methylpropanesulfonic acid; preferably, the water is deionized water.

[0051] In some specific embodiments, the quaternary ammonium salt functional monomer is selected from one or more of acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloyloxypropyltrimethylammonium chloride, dimethyldiallylammonium chloride, and vinylbenzyltrimethylammonium chloride.

[0052] In some specific embodiments, the imidazole ring-containing unsaturated monomer is selected from one or more of 1-vinylimidazole, 2-methyl-1-vinylimidazole, 4-vinylimidazole, 1-allylimidazole and 2-ethyl-1-vinylimidazole.

[0053] In some specific embodiments, the performance compensation monomer is polyethylene glycol monomethyl ether acrylate, with a molecular weight selected from 400, 600 or 800.

[0054] The core design of this invention lies in the precise regulation of molecular structure and the synergistic effect of functional monomers. Quaternary ammonium salt functional monomers and imidazole-containing unsaturated monomers are grafted onto the polycarboxylic acid backbone via free radical copolymerization, forming a unique polymer structure system of "synergistic dual antibacterial groups + performance compensation." This system achieves efficient, stable, and long-lasting antiseptic properties through the broad-spectrum synergistic mechanism of the dual antibacterial groups. Furthermore, the precise introduction of performance-compensating monomers effectively overcomes the adsorption performance degradation caused by cationic antibacterial groups, thus fully ensuring the polymer's excellent water-reducing and slump-retention properties.

[0055] Examples 1-8 cover different combinations of functional monomers, ratio ranges, and specific preparation conditions, aiming to comprehensively verify the overall improvement effect of the specific polymerization system of this invention on the anti-corrosion effect and working performance of the product. Simultaneously, this invention adds multiple control and comparative groups covering single functional monomers and commercially available conventional products to further highlight the significant practical advantages of the synergistic effect of the bifunctional monomers in this solution.

[0056] Example 1 Step S1: 250g deionized water, 100g GPEG3000, 0.8g sodium hypophosphite, 0.5g liquid alkali, 0.3g acryloyloxyethyltrimethylammonium chloride (DAC), 0.15g 1-vinylimidazole (1-VI), 0.02g ferrous sulfate and 0.7g MPEGAc-600 are added sequentially to a four-necked reactor equipped with a stirrer. Stirring is started (set to 300r / min) until all components are completely dissolved, and the system is kept at room temperature.

[0057] Step S2: Prepare an aqueous solution of 30% by mass from 12g of acrylic acid; prepare an aqueous solution of 0.3g of mercaptoethanol and 0.15g of vitamin C.

[0058] Step S3: 1.0g of ammonium persulfate is added to the reactor at one time to initiate the polymerization reaction. Then, the aqueous solution one and the aqueous solution two are simultaneously added to the reactor by a peristaltic pump, and the adding time is controlled to be 1.8h.

[0059] In step S4, after the addition is complete, the reaction is continued at room temperature for 1.5 hours, then naturally cooled to room temperature. Liquid alkali is added to adjust the pH of the system to 7.0, thus obtaining the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor. Finally, the mother liquor is compounded into a finished product with a solid content of 14% for later use.

[0060] Example 2 Step S1: 280g deionized water, 100g GPEG3000, 0.7g sodium hypophosphite, 0.6g liquid alkali, 0.15g acryloyloxyethyltrimethylammonium chloride (DAC), 0.15g methacryloyloxyethyltrimethylammonium chloride (DMC), 0.1g 1-vinylimidazole (1-VI), 0.05g 2-methyl-1-vinylimidazole (2-M-1-VI), 0.015g ferrous sulfate, and 0.7g MPEGAc-600 are sequentially added to a four-necked reactor equipped with a stirrer. Stirring is started (set to 300r / min) until all components are completely dissolved, and the system is kept at room temperature (25℃).

[0061] Step S2: Prepare an aqueous solution of 30% by mass from 13g of acrylic acid; prepare an aqueous solution of 0.3g of mercaptoethanol and 0.15g of vitamin C.

[0062] Step S3: 1.0g of ammonium persulfate is added to the reactor at one time to initiate the polymerization reaction. Then, the first aqueous solution and the second aqueous solution are simultaneously added to the reactor by a peristaltic pump, and the adding time is controlled to be 2.0h.

[0063] In step S4, after the addition is complete, the reaction is continued at room temperature for 2.0 hours, followed by natural cooling to room temperature. Liquid alkali is then added to adjust the pH of the system to 6.8, thus obtaining the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor. Finally, the mother liquor is compounded into a finished product with a solid content of 14% for later use.

[0064] Example 3 Step S1: 220g deionized water, 100g GPEG3000, 0.9g sodium hypophosphite, 0.4g liquid alkali, 0.4g dimethyl diallyl ammonium chloride (DMDAAC), 0.2g 4-vinylimidazole (4-VI), 0.025g ferrous sulfate and 0.7g MPEGAc-600 are added sequentially to a four-necked reactor equipped with a stirrer. Stirring is started (set speed to 300r / min) until all components are completely dissolved, and the system is kept at room temperature (30℃).

[0065] Step S2: Prepare an aqueous solution of 30% by mass from 11g of acrylic acid; prepare an aqueous solution of 0.3g of mercaptoethanol and 0.15g of vitamin C.

[0066] Step S3: 1.0g of ammonium persulfate is added to the reactor at one time to initiate the polymerization reaction. Then, the first aqueous solution and the second aqueous solution are simultaneously added to the reactor by a peristaltic pump, and the adding time is controlled to be 1.5h.

[0067] In step S4, after the addition is complete, the reaction is continued at room temperature for 1.0 h, then naturally cooled to room temperature. Liquid alkali is added to adjust the pH of the system to 7.2, thus obtaining the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor. Finally, the mother liquor is compounded into a finished product with a solid content of 14% for later use.

[0068] Example 4 Step S1: 260g deionized water, 100g GPEG3000, 0.6g sodium hypophosphite, 0.5g liquid alkali, 0.2g acryloyloxypropyltrimethylammonium chloride (APC), 0.1g 1-allylimidazole (1-AI), 0.02g ferrous sulfate and 0.7g MPEGAc-600 are added sequentially to a four-necked reactor equipped with a stirrer. Stirring is started (set speed to 300r / min) until all components are completely dissolved, and the system is kept at room temperature (27℃).

[0069] Step S2: Prepare an aqueous solution of 30% by mass from 14g of acrylic acid; prepare an aqueous solution of 0.3g of mercaptoethanol and 0.15g of vitamin C.

[0070] In step S3, 1.0g of ammonium persulfate is added to the reactor at one time to initiate the polymerization reaction. Then, the first aqueous solution and the second aqueous solution are simultaneously added to the reactor by a peristaltic pump, and the adding time is controlled to be 1.6h.

[0071] In step S4, after the addition is complete, the reaction is continued at room temperature for 1.2 hours, followed by natural cooling to room temperature. Liquid alkali is then added to adjust the pH of the system to 6.9, thus obtaining the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor. Finally, the mother liquor is compounded into a finished product with a solid content of 14% for later use.

[0072] Example 5 Step S1: 270g deionized water, 100g GPEG3000, 0.8g sodium hypophosphite, 0.5g liquid alkali, 0.35g vinylbenzyltrimethylammonium chloride (VBTAC), 0.17g 2-ethyl-1-vinylimidazole (2-E-1-VI), 0.022g ferrous sulfate and 0.7g MPEGAc-600 are added sequentially to a four-necked reactor equipped with a stirrer. Stirring is started (set speed to 300r / min) until all components are completely dissolved, and the system is kept at room temperature (30℃, simulating high-temperature pretreatment).

[0073] Step S2: Prepare an aqueous solution with a mass fraction of 30% by 12.5g of acrylic acid; prepare an aqueous solution with a mass fraction of 0.3g of mercaptoethanol and 0.15g of vitamin C.

[0074] Step S3: 1.0g of ammonium persulfate is added to the reactor at one time to initiate the polymerization reaction. Then, the first aqueous solution and the second aqueous solution are simultaneously added to the reactor by a peristaltic pump, and the adding time is controlled to be 1.7h.

[0075] In step S4, after the addition is complete, the reaction is continued at room temperature for 1.8 hours, then naturally cooled to room temperature. Liquid alkali is added to adjust the pH of the system to 7.1, thus obtaining the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor. Finally, the mother liquor is compounded into a finished product with a solid content of 14% for later use.

[0076] Example 6 Step S1: 240g deionized water, 100g GPEG3000, 0.75g sodium hypophosphite, 0.55g liquid alkali, 0.15g acryloyloxyethyltrimethylammonium chloride (DAC), 0.075g methacryloyloxyethyltrimethylammonium chloride (DMC), 0.075g acryloyloxypropyltrimethylammonium chloride (APC), 0.08g 1-vinylimidazole (1-VI), 0.04g 4-vinylimidazole (4-VI), 0.04g 1-allylimidazole (1-AI), 0.018g ferrous sulfate, and 0.7g MPEGAc-600 are sequentially added to a four-necked reactor equipped with a stirrer. Stirring is started (set to 300r / min) until all components are completely dissolved, and the system is kept at room temperature (26℃).

[0077] Step S2: Prepare an aqueous solution with a mass fraction of 30% by 13.5g of acrylic acid; prepare an aqueous solution with a mass fraction of 0.3g of mercaptoethanol and 0.15g of vitamin C.

[0078] Step S3: 1.0g of ammonium persulfate is added to the reactor at one time to initiate the polymerization reaction. Then, the aqueous solution one and the aqueous solution two are simultaneously added to the reactor by a peristaltic pump, and the adding time is controlled to be 1.9h.

[0079] In step S4, after the addition is complete, the reaction is continued at room temperature for 1.6 hours, then naturally cooled to room temperature. Liquid alkali is added to adjust the pH of the system to 6.7, thus obtaining the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor. Finally, the mother liquor is compounded into a finished product with a solid content of 14% for later use.

[0080] Example 7 Step S1: 255g deionized water, 100g GPEG3000, 0.8g sodium hypophosphite, 0.6g liquid alkali, 0.16g acryloyloxyethyltrimethylammonium chloride (DAC), 0.16g vinylbenzyltrimethylammonium chloride (VBTAC), 0.12g 1-vinylimidazole (1-VI), 0.08g 2-methyl-1-vinylimidazole (2-M-1-VI), 0.02g ferrous sulfate, and 0.7g MPEGAc-600 are sequentially added to a four-necked reactor equipped with a stirrer. Stirring is started (set to 300r / min) until all components are completely dissolved, and the system is kept at room temperature (29°C).

[0081] Step S2: Prepare an aqueous solution of 30% by mass with 15g of acrylic acid (this is the upper limit of acrylic acid ratio, which is intended to enhance water reduction performance); prepare an aqueous solution of 0.3g mercaptoethanol and 0.15g vitamin C.

[0082] Step S3: 1.0g of ammonium persulfate is added to the reactor at one time to initiate the polymerization reaction. Then, the aqueous solution one and the aqueous solution two are simultaneously added to the reactor by a peristaltic pump, and the adding time is controlled to be 1.8h.

[0083] In step S4, after the addition is complete, the reaction is continued at room temperature for 1.5 hours, then naturally cooled to room temperature. Liquid alkali is added to adjust the pH of the system to 7.0, thus obtaining the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor. Finally, the mother liquor is compounded into a finished product with a solid content of 14% for later use.

[0084] Example 8 Step S1: 265g deionized water, 100g GPEG3000, 0.7g sodium hypophosphite, 0.5g liquid alkali, 0.17g methacryloyloxyethyltrimethylammonium chloride (DMC), 0.17g dimethyl diallyl ammonium chloride (DMDAAC), 0.09g 4-vinylimidazole (4-VI), 0.09g 2-ethyl-1-vinylimidazole (2-E-1-VI), 0.021g ferrous sulfate, and 0.7g MPEGAc-600 are sequentially added to a four-necked reactor equipped with a stirrer. Stirring is started (set to 300r / min) until all components are completely dissolved, and the system is kept at room temperature (25℃).

[0085] Step S2: Prepare an aqueous solution of 30% by mass from 10g of acrylic acid (this is the lower limit ratio of acrylic acid, which is intended to weaken water reduction and enhance slump retention); prepare an aqueous solution of 0.3g of mercaptoethanol and 0.15g of vitamin C.

[0086] Step S3: 1.0g of ammonium persulfate is added to the reactor at one time to initiate the polymerization reaction. Then, the first aqueous solution and the second aqueous solution are simultaneously added to the reactor by a peristaltic pump, and the adding time is controlled to be 2.0h.

[0087] In step S4, after the addition is complete, the reaction is continued at room temperature for 1.9 hours, followed by natural cooling to room temperature. Liquid alkali is then added to adjust the pH of the system to 6.8, thus obtaining the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor. Finally, the mother liquor is compounded into a finished product with a solid content of 14% for later use.

[0088] Example 9 This embodiment provides an environmentally friendly, self-corroding polycarboxylate superplasticizer, the preparation method of which is basically the same as that of Example 1, except that the 1.0g ammonium persulfate in step S3 is replaced with 1.0g potassium persulfate.

[0089] Example 10 This embodiment provides an environmentally friendly, self-preservative polycarboxylate superplasticizer, the preparation method of which is basically the same as that of Example 1, except that the chain transfer agent 0.3g mercaptoethanol used in step S2 to prepare the aqueous solution is replaced with 0.3g 3-mercaptopropionic acid.

[0090] Example 11 This embodiment provides an environmentally friendly, self-preservative polycarboxylate superplasticizer, the preparation method of which is basically the same as that of Example 1, except that the reducing agent 0.15g vitamin C used in the preparation of aqueous solution II in step S2 is replaced with 0.15g sodium bisulfite.

[0091] Example 12 This embodiment provides an environmentally friendly, self-corroding polycarboxylate superplasticizer, the preparation method of which is basically the same as that of Example 1, except that the 12g acrylic acid used in the preparation of the aqueous solution in step S2 is replaced with 12g methacrylic acid.

[0092] Control group 1 The preparation process and other raw material ratios of this control group were the same as those in Example 1, except that the imidazole-containing functional monomer was removed from the ingredients in step S1, and 0.3g of acryloyloxypropyltrimethylammonium chloride (APC) was used as the quaternary ammonium salt functional monomer. All other conditions remained unchanged. The resulting polycarboxylate superplasticizer mother liquor was designated as D-1, and was subsequently compounded into a finished product with a solid content of 14% for later use.

[0093] Control group 2 The preparation process and other raw material ratios of this control group were the same as those in Example 1, except that the quaternary ammonium salt functional monomer was removed from the ingredients in step S1, and 0.15g of 1-allylimidazolium (1-AI) was selected as the imidazole ring functional monomer. All other conditions remained unchanged. The resulting polycarboxylate superplasticizer mother liquor was designated as I-1, and was subsequently compounded into a finished product with a solid content of 14% for later use.

[0094] Control group 3 The preparation process and other raw material ratios of this control group were the same as those in Example 1, except that the imidazole-containing functional monomer was removed from the ingredients in step S1, and 0.3g of acryloyloxyethyltrimethylammonium chloride (DAC) was used as the quaternary ammonium salt functional monomer. All other conditions remained unchanged. The resulting polycarboxylate superplasticizer mother liquor was designated as D-2, and was subsequently compounded into a finished product with a solid content of 14% for later use.

[0095] Control group 4 The preparation process and other raw material ratios of this control group were the same as those in Example 1, except that the quaternary ammonium salt functional monomer was removed in the preparation of the ingredients in step S1, and 0.15g of 1-vinylimidazole (1-VI) was selected as the imidazole ring functional monomer. All other conditions remained unchanged. The resulting polycarboxylate superplasticizer mother liquor was designated as I-2, and was subsequently compounded into a finished product with a solid content of 14% for later use.

[0096] Comparative Example 1 A commercially available ordinary polycarboxylate superplasticizer (model 911M) was used as control sample 1, and its solid content was adjusted to 14% using deionized water. This control sample was not subjected to any self-preservation or external preservative treatment and was used to evaluate the spoilage and deterioration of conventional products under natural conditions.

[0097] Comparative Example 2 A commercially available common polycarboxylate superplasticizer (model 911M) was used as control sample 2, with 0.2% by mass of an isothiazolinone preservative added to it in a physical compound, and its solid content was adjusted to 14%. This control sample was used to simulate the traditional external preservative mode to compare the superiority of the chemically modified self-preservative scheme of the present invention.

[0098] To systematically verify the self-preservation effect of the "quaternary ammonium salt monomer + imidazole ring monomer" bifunctional monomer synergistic design described in this invention, and to clarify the impact of the functional monomer combination on the core performance of the water-reducing agent, this invention conducted a multi-dimensional comprehensive performance evaluation of the samples prepared in Examples 1-8, Control Groups 1-4, and Comparative Examples 1-2. In the comparative evaluation, Comparative Example 1 was used as a blank baseline, and Comparative Example 2 was used as a reference for the traditional compound anti-corrosion mode. Through longitudinal comparison between the control group (single monomer) and the examples (dual monomer synergy), the technical advantages of this invention are highlighted. The evaluation criteria stipulate: antibacterial rate. For highly effective antibacterial properties, To effectively inhibit bacteria, if stored in a natural environment for 6 months without stratification, odor, or mold growth, it is considered to have long-term storage stability.

[0099] This validation included four main categories of comparative tests (dispersion performance test, antibacterial performance test, long-term storage stability test, and concrete mechanical property test). All tests were conducted strictly in accordance with current national standards and industry technical specifications. To ensure the objectivity and reproducibility of the data, three parallel samples were set up for each test group. Outliers were removed using the range method, and the arithmetic mean was taken as the final result. Except for specifically indicated test environments, basic test operations and sample preparation were conducted in a standard constant temperature and humidity chamber with an ambient temperature of 25±2℃ and a relative humidity of 60±5%.

[0100] The specific operating procedures for the dispersibility test (cement paste) strictly follow the GB / T8076-2008 standard to prepare cement paste, controlling the water-cement ratio at 0.29, and setting up 3 parallel samples for each group of samples. During the test, weigh 450g of cement and 130.5g of water, and accurately add the corresponding water-reducing agent sample with an admixture of 0.2% of the cement mass. Add the above materials to the cement paste mixer in sequence, and complete the preparation of cement paste by first mixing at low speed for 30s, stopping for 15s, and then mixing at high speed for 60s. After the paste preparation is completed, immediately pour the cement paste into a truncated conical mold (upper diameter 36mm, lower diameter 60mm, height 60mm) and smooth it with a scraper, then slowly pour it vertically upwards. Lift the mold to allow the paste to flow freely on the test plane. After the paste has completely stopped flowing, use calipers to measure the flow diameter in two mutually perpendicular directions and take the arithmetic mean of the two as the initial paste flowability. Then, place the remaining paste in a standard environment with a temperature of 25±2℃ and a relative humidity of 60±5% for 1 hour and repeat the above mold loading and testing steps to determine the paste flowability after 1 hour, and then calculate the 1-hour flowability loss rate. In the final data processing stage, use the range method to remove abnormal parallel sample data with a deviation greater than 5% of the average value, and take the average value of the remaining valid data as the final test result of this test item (see Table 2 for details) for recording and organization.

[0101] Table 2. Test results of flowability and flowability loss rate of each sample of paste

[0102] As shown in Table 2, the combination of DAC-type quaternary ammonium salt monomers and 1-VI-type imidazole ring-containing monomers exhibits significant synergistic advantages in the dispersion and slump retention properties of neat pulp. Specifically, Example 1, employing this bifunctional monomer synergistic system, demonstrates exceptionally superior overall performance, achieving an initial neat pulp flowability of 242 mm, a 1-hour flowability of 228 mm, and a 1-hour flowability loss rate of only 5.8%. In contrast, the control groups, which only introduced a single functional monomer, showed significant deterioration in slump retention properties over time. Specifically, the 1-hour flowability loss rate of control group 3 (containing only DAC monomers) was 10.2%, and that of control group 4 (containing only 1-VI monomers) was also 10.0%. Meanwhile, the 1-hour flowability loss rate of the commercially available blank control example 1, which underwent no preservative chemical modification, was 10.3%. The above comparative data fully demonstrates that the introduction of a single cationic or imidazole ring antibacterial group will cause competitive adsorption on the surface of cement particles, thereby weakening the slump retention capacity of the water-reducing agent. However, this invention, by copolymerizing and grafting DAC-type monomers with 1-VI-type monomers with specific structures, not only does not sacrifice the basic water reduction rate, but also significantly inhibits the loss of the fluidity of the cement paste over time through the steric hindrance synergy and performance compensation mechanism of the two groups on the polymer backbone. This perfectly overcomes the technical bias that traditional anti-corrosion modification easily leads to the loss of the working performance of the water-reducing agent.

[0103] Furthermore, the data from Examples 2 to 6 show that when other types of quaternary ammonium salt monomers (such as DMC, DMDAAC, APC, VBTAC) are combined with imidazole ring monomers with different substituents (such as 2-M-1-VI, 4-VI, 1-AI, 2-E-1-VI) for multi-component copolymerization, the initial flowability of the system remains between 198 mm and 227 mm, and the flowability loss rate over 1 hour is controlled between 7.5% and 13.6%, both significantly better than the corresponding single monomer schemes (such as the loss rates of control group 1 and control group 2, which are as high as 15% and 16%, respectively). This strongly confirms the universality and structural stability of the bifunctional monomer synergistic design of the present invention under different chemical structure combinations. In addition, Examples 7 and 8 respectively verified the boundary effect of the polymer raw material ratio. Example 7, which uses the upper limit of the acrylic acid ratio, showed a high initial fluidity of 231 mm, highlighting its advantage in enhancing water reduction performance. Example 8, which uses the lower limit of the acrylic acid ratio, achieved a low fluidity loss rate of only 7.5%, verifying its design intention of weakening initial water reduction but strongly ensuring slump retention performance over time.

[0104] The specific operating procedures for the dispersion performance and mechanical properties (concrete) test strictly followed the GB / T 50081-2019 standard to prepare C40 grade concrete. Three parallel test blocks of 150mm×150mm×150mm were set up for each sample group, and the water-reducing agent dosage was controlled at 0.2% of the cement mass. During the test, a forced concrete mixer was used. Sand, aggregate, and cement were added sequentially and dry-mixed for 5 seconds, followed by the addition of a pre-dissolved water-reducing agent aqueous solution and wet-mixing for another 90 seconds to obtain a homogeneous concrete mixture. After mixing, the concrete mixture was immediately layered into a slump cone and compacted layer by layer (each layer was compacted uniformly 25 times). After leveling the cone opening, the slump cone was lifted vertically and steadily, and its slump value was measured. After the mixture had stabilized due to slump expansion, the phases were measured using a steel ruler. The maximum expansion diameter in two mutually perpendicular directions is taken as the arithmetic mean of the two as the expansion degree. Subsequently, the remaining concrete mixture is filled into the test block mold and vibrated to compact it. After smoothing the surface, it is transferred to a standard curing chamber with a temperature of 20±2℃ and a relative humidity of ≥95% for standard curing. The corresponding test blocks are taken out at 7d and 28d respectively, and the compressive strength is determined by a pressure testing machine. The loading speed during the test is strictly controlled at 2.5kN / s. In the final data processing stage, abnormal test block data with a deviation of more than 10% from the average value of the measured compressive strength are removed. The arithmetic mean of the test values ​​of the remaining valid test blocks is taken as the final test result of this test item (see Table 3 for details) and recorded and organized.

[0105] Table 3. Test results of workability and mechanical properties of concrete samples.

[0106] As shown in Table 3, the combination of DAC-type quaternary ammonium salt monomers and 1-VI-type imidazole ring-containing monomers exhibits good dispersion performance in concrete, while also demonstrating excellent mechanical properties. Specifically, Example 1, employing this optimal bifunctional monomer synergistic system, achieved a concrete slump of 210 mm and a spread of 510 mm. While maintaining excellent initial working performance comparable to the commercially available untreated baseline comparison example 1 and the traditional physical compound anti-corrosion comparison example 2, its mechanical properties were significantly improved. The 7-day and 28-day compressive strengths of Example 1 reached 36.5 MPa and 43.3 MPa, respectively, far exceeding the 34.9 MPa and 41.9 MPa of the commercially available baseline comparison example 1, and also significantly superior to the control group 3, which only introduced a single DAC monomer, and the control group 4, which only introduced a single 1-VI monomer. This fully demonstrates that the grafting of the dual anti-corrosion groups of the specific structure of this invention onto the polycarboxylic acid backbone not only does not degrade the dispersion state of cement particles by the water-reducing agent due to the introduction of cationic groups, but also effectively promotes the early and late hydration process of cement through the optimization of polymer molecular spatial conformation and the synergy of performance-compensating monomers, achieving a perfect synergy between anti-corrosion modification and the development of concrete mechanical strength. Furthermore, data from Examples 2 to 6 show that when other quaternary ammonium salt monomers such as DMC, DMDAAC, APC, and VBTAC are copolymerized with imidazole ring monomers with different substituents such as 2-M-1-VI, 4-VI, 1-AI, and 2-E-1-VI, the resulting concrete mixture exhibits a stable slump between 180 mm and 205 mm, and a 28-day compressive strength maintained at an excellent level of 42.1 MPa to 43.1 MPa. The overall mechanical properties are superior to or equivalent to those of commercially available ordinary water-reducing agents, strongly demonstrating that this dual-monomer synergistic system possesses good universality and stable macroscopic strengthening effects under different chemical structural combinations. Furthermore, Examples 7 and 8 further verified the precise control effect of the polymerization ratio boundary on engineering performance. Example 7, which uses the upper limit of the acrylic acid ratio, exhibits a high slump of 210 mm and a high later strength of 43.8 MPa, perfectly balancing the requirements of high water reduction and high strength. Although the initial slump of Example 8, which uses the lower limit of the acrylic acid ratio, is slightly reduced to 195 mm, its 28-day compressive strength climbs to the highest in the entire range at 44.0 MPa. This fully demonstrates that the technical solution of the present invention can flexibly adapt to the customized application scenarios of different engineering projects for high water reduction or high strength slump retention of concrete by finely adjusting the acid-ether ratio.

[0107] The specific operating procedures for the antibacterial performance test include: First, under aseptic conditions, each water-reducing agent sample is diluted to a mass concentration of 5% to prepare the sample test solution, and sterile deionized water is set up as a blank control group. Each test group is strictly set up with 3 parallel samples. Then, 1% by volume of Escherichia coli (standard strain preservation number: ATCC 25922) and Aspergillus niger (standard strain preservation number: ATCC) are inoculated into each test solution and control solution, respectively. The standard bacterial suspension (16404) was thoroughly mixed and transferred to a constant temperature and humidity incubator at 37℃ and 90% relative humidity for static incubation. At 24h and 7d, the corresponding test solutions and blank control solutions were collected and diluted to appropriate colony reading concentrations using a 10-fold serial dilution method. 0.1mL of the diluted solution was accurately pipetted and evenly spread onto the corresponding culture medium surface (nutrient agar for Escherichia coli and Sabouraud agar for Aspergillus niger). The culture dishes were then placed under the appropriate conditions for further incubation (E. coli...). Bacillus was cultured for 24 hours (standard culture time), and Aspergillus niger for 72 hours (standard culture time). After the culture was completed, the total number of colonies was counted using a colony counter, and the inhibition rate of each sample was calculated accordingly. In the final data processing stage, abnormal parallel sample data with a deviation greater than 5% of the average value were removed using the range method, and the arithmetic mean of the remaining valid parallel sample test values ​​was taken as the final test result for this test item. In addition, throughout the entire culture and testing period, the turbidity and odor changes of each sample test solution were observed and recorded by the naked eye, which were used as auxiliary indicators to comprehensively judge the macroscopic stability of the product's antibacterial effect. The results of the antibacterial performance test are detailed in Table 4.

[0108] Table 4. Results of antibacterial performance tests for each sample (Escherichia coli + Aspergillus niger).

[0109] As shown in Table 4, the examples of the "quaternary ammonium salt + imidazole ring-containing" bifunctional monomer combination exhibit significantly better antibacterial performance than the control group and commercially available comparative examples using single functional monomers. This fully verifies the self-preservative advantage of the bifunctional monomer synergistic grafting system, and the synergistic antibacterial effect possesses excellent broad-spectrum (simultaneously and effectively inhibiting bacteria such as Escherichia coli and fungi such as Aspergillus niger) and persistence. Specifically, Example 1, which uses the optimal combination of DAC-type quaternary ammonium salt monomers and 1-VI-type imidazole ring-containing monomers, shows the most outstanding performance, with antibacterial rates of 98.2% and 97.5% against Escherichia coli at 24 h and 7 days, respectively, and antibacterial rates against Aspergillus niger reaching 96.8% and 96.1%, respectively, fully meeting the preset high-efficiency antibacterial evaluation criteria. In contrast, the control groups that introduced only a single functional monomer showed obvious limitations and decreased efficacy. For example, the control group 3, which was grafted with only a single DAC monomer, had its 7-day inhibition rates of Escherichia coli and Aspergillus niger reduced to 87.5% and 81.8%, respectively, while the control group 4, which was grafted with only a single 1-VI monomer, also reduced to 86.9% and 81.2%, respectively, both far below the levels of Example 1. This strongly demonstrates that there is a significant positive synergistic effect between cationic quaternary ammonium salt groups and nitrogen-containing heterocyclic imidazole groups in disrupting microbial cell membranes and inhibiting intracellular enzyme activity. Furthermore, the commercially available blank baseline control example 1, which was not treated with preservatives, showed severe microbial growth over time, with its 7-day inhibition rates of *E. coli* and *Aspergillus niger* dropping to only 68.9% and 60.2%, respectively. In contrast, control example 2, which used traditional physical admixtures of isothiazolinone preservatives, achieved an initial 24-hour *E. coli* inhibition rate of 92.5%, but this rapidly declined to 88.7% by 7 days, fully exposing the inherent defects of physically blended preservatives being easily released and degraded. Further, data from Examples 2 to 8 show that the other different types and ratios of bifunctional monomer synergistic systems covered by this invention can still maintain stable 7-day *E. coli* and *Aspergillus niger* inhibition rates within the effective inhibition range of over 93.2% and 91.0%, respectively. This completely overcomes the technical bottleneck of traditional water-reducing agents being prone to spoilage and deterioration, successfully achieving a substantial technological leap from "short-term physical extension" to "long-term chemical endogenous" preservative function.

[0110] The specific operating procedures for long-term storage stability testing include: First, each group of water-reducing agent samples to be tested is separately packaged into transparent polyethylene plastic bottles. Each group of samples is strictly prepared with 6 parallel test samples. Three of these samples are placed in a normal temperature natural environment with a daily average temperature of 5–35℃ and a relative humidity of 40%–80% to simulate the normal annual climate changes experienced by actual engineering projects, including diurnal temperature variations and seasonal changes. The other three samples are strictly placed in a constant temperature environment of 35℃. By maintaining a constant output of the annual temperature peak, this aims to simulate the continuous high-temperature and harsh service conditions under summer closed storage or extreme climates with no diurnal temperature variation. All test samples must be sealed and protected from direct sunlight and cross-contamination. During a continuous 60-day monitoring period, at the time points of 10 days, 20 days, 30 days, 45 days, and 60 days of storage, the color, transparency, and whether stratification occurs are regularly observed and recorded in detail for each sample. The study examined the appearance changes, including the presence or absence of precipitation, and simultaneously tested the system for any off-odors or putrid smells. A pH meter was used to accurately measure the pH value of the samples to track changes in acidity and alkalinity. Furthermore, the physical water reduction rate of each group of samples was simultaneously measured at each of the aforementioned monitoring points, and the water reduction retention rate (i.e., the percentage of water reduction rate after storage compared to the initial water reduction rate) was calculated. After eliminating abnormal test data using the range method, the arithmetic mean of the remaining parallel sample values ​​was taken as the final measurement result for that period. Finally, this experiment uniformly used "no obvious appearance deterioration, no putrid odor generation, pH fluctuation ≤0.5, and water reduction retention rate ≥90% after 60 days of continuous storage" as the core qualification criteria. This was used to scientifically and comprehensively evaluate the long-term storage stability and self-corrosion protection time of each embodiment and comparative sample under complex service environments. Detailed evaluation and test results are shown in Table 5.

[0111] Table 5. Results of long-term storage stability tests for each sample (60 days)

[0112] As shown in Table 5, the examples of the "quaternary ammonium salt + imidazole ring-containing" bifunctional monomer combination exhibit significantly better long-term storage stability than the control group and commercially available comparative examples of single functional monomers. This thoroughly verifies the practicality and storage reliability of the product of this invention, perfectly meeting the stringent requirements for long-term storage, transportation, and on-site use in industrial production. Specifically, Example 1, which uses the optimal ratio of DAC-type quaternary ammonium salt monomers and 1-VI-type imidazole ring-containing monomers, performed the best. After 60 days of constant temperature storage, its appearance remained colorless and transparent, without any stratification or odor generation. The pH fluctuation of the system was only a very small 0.2, and the water reduction retention rate was as high as 98.5%, far exceeding the set qualification evaluation standard. Furthermore, the data from Examples 2 to 8 show that the other bifunctional monomer combination schemes covered by this invention did not exhibit any deterioration phenomena such as stratification, precipitation, or off-odors during the 60-day long-term monitoring period. The pH value changes were strictly controlled within an extremely narrow range of 0.3 to 0.5, and the water reduction rate retention rate remained stably at a high level of 95.1% to 97.9%, fully demonstrating the high physical and chemical stability of the bifunctional grafted structure under complex storage environments. In contrast, control groups 1 to 4, which introduced only a single functional monomer, not only exhibited varying degrees of turbidity or stratification in appearance, but also showed a widening pH range of 0.6 to 0.7, indicating that a single functional group cannot provide a long-lasting and comprehensive antibacterial barrier, leading to partial degradation of the polymer system. Notably, the commercially available blank baseline control example 1, which had not undergone any preservative treatment, showed severe turbidity, stratification, and a noticeable putrid odor after 60 days of storage. Its pH value changed drastically by 1.2, and the water reduction retention rate dropped sharply to 85.7%, indicating that the product had completely deteriorated and failed. While control example 2, which used a traditional physical preservative admixture method, did not produce a noticeable odor, it still showed turbidity and stratification, accompanied by a large pH fluctuation of 0.8. This directly exposed the inherent technical defects of traditional physical compound systems, which are prone to preservative degradation and system demulsification failure during long-term storage. The detailed data comparison above strongly demonstrates that the self-preservative polycarboxylate superplasticizer designed in this invention fundamentally blocks the pathways of microbial erosion and macromolecular chain breakage and degradation by stably anchoring the dual-effect anti-corrosion groups to the polymer backbone in the form of covalent bonds, thus achieving excellent performance retention and constant sensory quality throughout the entire product life cycle.

[0113] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An environmentally friendly, self-corrosion-resistant polycarboxylate superplasticizer, characterized in that, Based on 100 parts by weight of polyether macromonomer, the following polymerization raw materials are included: 10-15 parts of unsaturated carboxylic acids and their derivatives, 0.1-0.5 parts of quaternary ammonium salt functional monomers, 0.05-0.25 parts of imidazole ring-containing unsaturated monomers, 0.3-0.9 parts of performance-compensating monomers, 0.5-1.5 parts of initiator, and 200-300 parts of water.

2. The environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer according to claim 1, characterized in that, The polymerization raw materials also include: 0.1 to 0.5 parts of chain transfer agent, 0.05 to 0.25 parts of reducing agent, and auxiliary raw materials, including 0.5 to 1.0 parts of sodium hypophosphite and 0.01 to 0.03 parts of ferrous sulfate. The polymerization raw materials also include liquid alkali for adjusting the pH value. The chain transfer agent is selected from one or more of mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptoethanol, or sodium methylpropenesulfonate. The reducing agent is selected from one or more of sodium bisulfite, vitamin C, ferrous sulfate, or glucose.

3. The environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer according to claim 1, characterized in that, The number-average molecular weight of the polyether macromonomer is between 2900 and 3100 g / mol; the molecular formula of the polyether macromonomer is: CH2=C(CH3)CH2O(CH2CH2O) n H, where n is a positive integer.

4. The environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer according to claim 1, characterized in that, The quaternary ammonium salt functional monomer is selected from one or more of acryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, acryloyloxypropyltrimethylammonium chloride, dimethyldiallylammonium chloride, and vinylbenzyltrimethylammonium chloride.

5. The environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer according to claim 1, characterized in that, The imidazole-containing unsaturated monomer is selected from one or more of 1-vinylimidazole, 2-methyl-1-vinylimidazole, 4-vinylimidazole, 1-allylimidazole and 2-ethyl-1-vinylimidazole.

6. The environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer according to claim 1, characterized in that, The performance-compensating monomer is polyethylene glycol monomethyl ether acrylate, and its number-average molecular weight is selected from 400, 600 or 800; the grafting amount of the performance-compensating monomer is 0.5 to 0.9 parts.

7. The environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer according to claim 1, characterized in that, The unsaturated carboxylic acid and its derivatives are selected from one or more of acrylic acid, acrylamide, methacrylic acid, maleic anhydride, methyl acrylate, dimethyl maleate, and 2-acrylamido-2-methylpropanesulfonic acid; the water is deionized water; and the initiator is selected from one or more of ammonium persulfate and potassium persulfate.

8. A method for preparing an environmentally friendly, self-corroding polycarboxylate superplasticizer as described in any one of claims 1 to 7, characterized in that, The method includes: S1, add the water, polyether macromonomer, quaternary ammonium salt functional monomer, imidazole ring-containing unsaturated monomer, performance compensation monomer, and auxiliary raw materials to the reaction vessel in the specified amounts, and stir at room temperature until completely dissolved to obtain the prepared base material; S2, prepare the unsaturated carboxylic acid and its derivatives into an aqueous solution one, and prepare the reducing agent and chain transfer agent into an aqueous solution two; S3, after adding an initiator to the reactor to initiate the polymerization reaction, the first aqueous solution and the second aqueous solution are simultaneously added dropwise to the reactor; S4, after the addition is complete, keep the reaction at a constant temperature, allow it to cool naturally, and adjust the pH value to neutral to obtain the environmentally friendly self-preservative polycarboxylate superplasticizer mother liquor.

9. The preparation method of the environmentally friendly self-corrosion-resistant polycarboxylate superplasticizer according to claim 8, characterized in that, In step S1, the temperature of the reactor is controlled at 25-30°C; in step S3, the mass fraction of aqueous solution one is 30%, and the dropwise addition time of aqueous solution one and aqueous solution two is 1.5-2 hours; in step S4, the heat preservation reaction is carried out at room temperature for 1-2 hours, and after the heat preservation is completed, it is naturally cooled to room temperature, and liquid alkali is added to adjust the pH value to 6.5-7.

5.

10. The application of an environmentally friendly, self-corrosion-resistant polycarboxylate superplasticizer as described in any one of claims 1 to 7 in the preparation of building materials or concrete.

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