Polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention belongs to the technical field of concrete, and particularly relates to a polycarboxylate superplasticizer and a preparation method thereof. The polycarboxylate superplasticizer is prepared from an unsaturated polyether macromonomer, an unsaturated acid monomer, an unsaturated carbonate monomer, an unsaturated amino monomer, an initiator, a reducing agent, a chain transfer agent, deionized water, a solubilizer and organic alcohol amine. Wherein the unsaturated carbonate monomer is allyl methyl carbonate, and the unsaturated amino monomer is 2-aminoethyl methacrylate hydrochloride. According to the invention, excellent water reducing effect and stable control capability on concrete slump are maintained, and micro-cracks can be effectively made up through a dual mechanism formed by carbonate release and CaCO3 precipitation in the early and later stages of concrete hardening.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete, and particularly relates to a polycarboxylate water reducer and a preparation method thereof. Background Art

[0002] As humanity's first major engineering material, concrete is the most consumed building material and is widely used in a variety of projects, including roads, bridges, water conservancy projects, tunnels, and nuclear power plants. However, cracks, caused by inherent drying and plastic shrinkage in concrete and temperature fluctuations, are common. These cracks can reduce the durability of buildings, accelerate steel corrosion, and severely impact their service life. This is particularly harmful for century-long projects like bridges. Globally, crack control has become a key issue in improving the safety and cost-effectiveness of concrete structures.

[0003] Traditional methods of controlling concrete cracks mostly rely on external repairs and regular maintenance. On the one hand, the cost is high, and on the other hand, the repair effect is easily affected by construction quality and environmental conditions, making it difficult to achieve active, long-term self-repair. In recent years, concrete self-repair technology has emerged. Chinese patent CN119409453A discloses a self-healing high-toughness concrete and its preparation method, which mainly realizes the self-repair of concrete after cracking by over-configuring the precursor of cementitious materials, and combines mixed fibers to enhance the toughness of concrete, thereby realizing low-cost configuration of concrete and a new type of self-healing concrete that integrates control and repair; however, this method requires external moisture penetration, and the self-healing effect of concrete cracks in a dry environment is not good; in addition, the multi-fiber ratio used therein also has the problem of difficult dispersion and easy agglomeration. Chinese patent CN117209208A discloses a method for preparing a self-healing rigid waterproof material for concrete. The method uses a cement base, silica powder, a polymer modifier, steel fiber, a magnesium oxide microcapsule self-healing agent, and a waterproofing additive. However, this method suffers from the uncontrollable expansion of the magnesium oxide in the magnesium oxide microcapsule self-healing agent, which can cause the concrete to crack again. Chinese patent CN116751027A discloses a self-healing crystalline protective material for concrete, its preparation method, and its application. This self-healing crystalline protective material has good permeability and can fully fill the capillary pores and fine cracks in concrete, repairing concrete cracks. However, this method requires high construction technology and has a significant impact on the workability of the concrete. Summary of the Invention

[0004] The present invention aims to provide a polycarboxylate water-reducing agent that not only maintains excellent water-reducing effect and stable control over the slump of concrete, but also effectively compensates for microcracks in the early and late stages of concrete hardening through a dual mechanism of carbonate release and CaCO3 precipitation. The present invention also provides a method for preparing the polycarboxylate water-reducing agent.

[0005] The polycarboxylate water-reducing agent of the present invention is prepared from an unsaturated polyether macromonomer, an unsaturated acid monomer, an unsaturated carbonate monomer, an unsaturated amino monomer, an initiator, a reducing agent, a chain transfer agent, deionized water, a solubilizer and an organic alcoholamine; wherein the unsaturated carbonate monomer is allyl methyl carbonate, and the unsaturated amino monomer is 2-aminoethyl methacrylate hydrochloride.

[0006] The unsaturated polyether macromonomer is isopentenyl polyoxyethylene ether or methallyl polyoxyethylene ether; The structural formula of isopentenyl polyoxyethylene ether is as follows:

[0007] Where n1 is 25-100; The structural formula of methyl allyl polyoxyethylene ether is as follows:

[0008] Where n1 is 25-100.

[0009] The unsaturated acid monomer is acrylic acid, and the molar ratio of the unsaturated polyether macromonomer, the unsaturated acid monomer, the unsaturated carbonate monomer and the unsaturated amino monomer is 1:3-4:0.5-0.8:0.2-0.5.

[0010] The initiator is one of ammonium persulfate, hydrogen peroxide or sodium peroxide, and the amount of the initiator is 1-2 wt.% of the total mass of the unsaturated polyether macromonomer, the unsaturated acid monomer, the unsaturated carbonate monomer and the unsaturated amino monomer.

[0011] The reducing agent is vitamin C or sodium bisulfite, and the mass ratio of the initiator to the reducing agent is 1:0.6-1.0.

[0012] The chain transfer agent is mercaptoethanol or mercaptopropionic acid, and the amount of the chain transfer agent is 0.8-2.0% of the total mass of the unsaturated polyether macromonomer, the unsaturated acid monomer, the unsaturated carbonate monomer and the unsaturated amino monomer; the solubilizer is ethanol, and the mass ratio of the unsaturated carbonate monomer to the solubilizer is 1:1-2.

[0013] The organic alcoholamine is diethanolamine or triethanolamine.

[0014] The preparation method of the polycarboxylate water-reducing agent of the present invention comprises the following steps: (1) Unsaturated polyether macromonomer and deionized water are prepared into a base liquid, and heated to obtain a preheated base liquid; unsaturated acid monomer, unsaturated carbonate monomer, unsaturated amine monomer, reducing agent, chain transfer agent, solubilizer and deionized water are prepared into solution A; initiator and deionized water are prepared into solution B; (2) Solution A and solution B are simultaneously added dropwise to the preheated base solution for reaction. After the addition is completed, the reaction is continued at a temperature of 100 °C. The temperature is lowered, an organic alcohol amine is added to adjust the pH value, and deionized water is added for dilution to obtain a polycarboxylic acid water reducer.

[0015] In step (1), the concentration of the bottom solution is 50-55 wt.%, which is heated to 40-50°C, the concentration of solution A is 30-40 wt.%, and the concentration of solution B is 1.0-2.0 wt.%.

[0016] In step (2), the addition time of solution A is 2.0-3.0h, the addition time of solution B is 2.5-3.5h, the reaction temperature is 40-50°C, the insulation reaction time is 1.0-2.0h, the insulation reaction temperature is 40-50°C, the temperature is lowered to below 30°C, the pH value is adjusted to 7.0-8.0, and the solid content of the polycarboxylate water reducer is 35-40wt.%.

[0017] When the polycarboxylate water-reducing agent of the present invention is applied to concrete, the dosage of the polycarboxylate water-reducing agent is 0.2-0.5% of the weight of the concrete cementitious material.

[0018] The present invention provides a polycarboxylate water-reducing agent for promoting the self-healing of concrete cracks. The polycarboxylate water-reducing agent is simple to prepare, has high repair efficiency, and does not affect the original mechanical properties of the material. The present invention introduces a controllable release carbonate functional group into the traditional polycarboxylate molecular chain. When the polycarboxylate water-reducing agent and cement are dispersed in water, the carbonate group will be gradually released in the high alkaline environment of the concrete and react with the Ca in the cement-based material. 2+ The ion reaction generates stable calcium carbonate precipitates, which can not only precipitate and fill the concrete surface and internal micropores, but also concentrate on the microcrack tips to form "self-generated" repair bodies, thereby sealing cracks and capillary pores and achieving efficient automatic repair of concrete.

[0019] The present invention achieves molecular-level functional coupling by introducing allyl methyl carbonate, 2-aminoethyl methacrylate hydrochloride and organic alcoholamine into the polycarboxylic acid main chain: 1. Targeted delivery and in situ positioning The carboxyl groups carried by the polycarboxylic acid main chain can be firmly adsorbed on the surface of cement stone. Therefore, the polycarboxylic acid main chain together with the allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride side chains can be anchored in the interface transition zone, ensuring that self-healing active components such as allyl methyl carbonate can play a role in situ at the location to be repaired.

[0020] 2. Sustained release channel The polycarboxylate water-reducing agent of the present invention can achieve sustained release of carbonate ions through its unique intramolecular structure formed by copolymerization, providing long-term self-healing ability for concrete. The specific mechanism is: On the polymer molecular chain of the present invention, some of the allyl methyl carbonate side chains are spatially adjacent to one or more 2-aminoethyl methacrylate hydrochloride side chains due to the folding of the molecular chain. The 2-aminoethyl methacrylate hydrochloride side chains contain highly polar amino groups (-NH2) and can interact with water molecules through hydrogen bonds to construct a local hydrophilic microenvironment around the allyl methyl carbonate side chains.

[0021] When the allyl methyl carbonate side chain is partially or completely encapsulated by this hydrophilic microenvironment, its hydrolysis behavior is regulated by the following two synergistic effects: (1) Steric shielding and local environmental buffering: The hydrophilic microenvironment forms an effective steric shield for the ester bond of allyl methyl carbonate, reducing the frequency of attack by high-concentration hydroxide ions (OH⁻) from the outside. At the same time, the amino group on the side chain of 2-aminoethyl methacrylate hydrochloride has a local pH buffering capacity, which makes the alkalinity in the microenvironment lower than the external concrete pore solution, thereby jointly delaying the hydrolysis rate of the ester bond.

[0022] (2) A stable "quasi-complex" structure formed by intermolecular interactions: The lone pair of electrons of the amino group on the side chain of 2-aminoethyl methacrylate hydrochloride can generate hydrogen bonds or dipole-dipole interactions with the oxygen atoms in the carbonyl group or ether bond on the side chain of allyl methyl carbonate, forming a dynamically stable non-covalent "quasi-complex" structure; the existence of this structure further stabilizes the chemical properties of the side chain of allyl methyl carbonate and reduces its activity in hydrolysis reactions.

[0023] In summary, through the above-mentioned synergistic effect, this part of the allyl methyl carbonate side chain affected by the 2-aminoethyl methacrylate hydrochloride side chain can release carbonate in a smoother and more lasting manner, thereby forming a continuous slow-release repair channel for long-term damage to concrete.

[0024] 3. High-density nucleation and accelerated growth The amine groups on the adjacent 2-aminoethyl methacrylate hydrochloride side chains in the copolymer structure of the present invention are 2+ It has excellent coordination ability and can convert free Ca 2+ enriched at the crack interface; enriched Ca 2+ CO3 released in the same chain 2- Close coupling at the molecular scale greatly improves the CaCO3 crystal nucleus density and growth rate.

[0025] 4. Performance Improvement The hydrophilic groups (amine groups) on 2-aminoethyl methacrylate hydrochloride enhance the dispersion stability of the polycarboxylate superplasticizer (PCE) macromolecule itself in a high ionic strength environment. The concrete pore solution is a complex electrolyte solution with high ion concentration (rich in Ca 2+ 、Na + , K + 、SO4 2- In this solution, the negative charges (carboxyl groups) on the PCE backbone are "shielded" by cations, causing the molecular chain to curl and the comb-like side chains to collapse, thus losing their steric dispersion ability. However, the -NH2 groups on 2-aminoethyl methacrylate hydrochloride form strong hydrogen bonds with water molecules, forming a stable hydration layer around the PCE molecules. This hydration layer acts as a "protective coat," physically preventing the side chains from collapsing and the molecules from agglomerating. This allows PCE to maintain its extended conformation even in a high-ionic environment, thereby maintaining its dispersion stability.

[0026] Improved water-reduction efficiency: Water-reduction efficiency depends on the ability of PCE molecules to disperse cement particles. As mentioned above, the hydrophilic groups on 2-aminoethyl methacrylate hydrochloride maintain the extended conformation of the PCE molecules, maximizing their steric hindrance. Stronger steric hindrance means more efficient dispersion, requiring less water to achieve the same fluidity, resulting in higher water-reduction efficiency.

[0027] Improved slump retention: Slump retention refers to the ability of a paste to maintain fluidity over a period of time. The stable hydration layer formed by the hydrophilic groups on 2-aminoethyl methacrylate hydrochloride not only resists ion attack but also slows the rate at which PCE molecules are encapsulated or adsorbed by the hydrating cement product. This allows more PCE molecules to remain active for a longer period of time, continuously dispersing cement particles, thereby extending the fluidity of the paste and demonstrating superior slump retention.

[0028] 5. The organic alcohol amines in this invention constitute a second, long-term, sustained-release mechanism. The alkaline amine groups of the organic alcohol amines can capture carbon dioxide dissolved in the pore solution (the carbon dioxide dissolved in the pore solution originates from the atmosphere and the reversible reaction of carbonate ions in water), undergoing a reversible reaction to form a stable organic alcohol amine-CO2 complex, which acts as a "molecular reservoir" of CO2 in the system. The release of stored CO2 from the organic alcohol amine-CO2 complex is driven by a healing reaction: when the formation of CaCO3 precipitation consumes carbonate ions in the pore solution, the chemical equilibrium is disrupted. Based on the principle of equilibrium shift, the organic alcohol amine-CO2 complex subsequently decomposes, releasing stored CO2 to replenish the consumed carbonate ions. This process forms an adaptive system that responds to internal damage and supplies repair substances on demand, effectively repairing late-stage cracks and ensuring the long-term self-healing ability of concrete.

[0029] In summary, the present invention fixes allyl methyl carbonate, 2-aminoethyl methacrylate hydrochloride and organic alcohol amine on the same polymer skeleton by chemical copolymerization, thereby constructing a multi-level synergistic self-healing system.

[0030] The polycarboxylate water-reducing agent of the present invention introduces degradable carbonate units, 2-aminoethyl methacrylate hydrochloride containing -NH2 side chains, and organic alcohol amines, which can release carbonate ions in alkaline cement slurry in stages: (1) Mixing period (0-2h): carbonate ion release is less than 10%, ensuring that rheology and strength are not affected; (2) Initial hardening period (3h-6 days, pH ≥ 13): ester bonds of carbonate ions are hydrolyzed, and 30-60% CO3 is released cumulatively. 2- , reacts with Ca(OH)2 to form CaCO3; (3) In the middle and late stages of hardening (7-28 days): the organic alcohol amine-CO2 complex slowly decomposes and reacts with the remaining carbonate to release more than 80% CO3 2- -NH2 can react with Ca 2+ Coordination accelerates the nucleation of CaCO3 in cracks or pores; -NH2 improves the hydrophilicity and dispersion stability of the side chain; the organic alcohol amine-CO2 complex continuously releases CO2 in the later stage, and double synergizes with the carbonate hydrolysis to achieve higher self-healing efficiency. 2- It preferentially deposits at the crack tips, forming microneedle-platelet CaCO3 crystals that fill and block the channels.

[0031] The beneficial effects of the present invention are as follows: (1) Dual carbonate release mechanism: The synergistic effect of carbonate hydrolysis and organic alcohol amine-CO2 complex decomposition not only produces carbonate ions continuously and controllably in a high alkaline environment, but also achieves fault-like release, meeting the different needs of early construction and later self-healing.

[0032] (2) Excellent CaCO3 nucleation and distribution: -NH2 side chain can react with Ca2+ Coordination accelerates the nucleation of CaCO3 in the capillary pores and microcracks; the organic alcohol amine reacts with the CO2 dissolved in the pore solution to stabilize the pH of the system in the weak alkaline range, making CaCO3 2+ / CO3 2- The binding rate and precipitation morphology are more uniform and fine, which is beneficial to the improvement of early strength and provides a second source of carbonate for later self-healing.

[0033] (3) Simple and efficient industrial preparation: The use of a redox initiation system significantly improves the initiation efficiency and polymerization yield. The reaction conditions are mild and the energy consumption is low, making it suitable for large-scale production and on-site construction applications. DETAILED DESCRIPTION

[0034] The present invention is further described below with reference to the following examples.

[0035] Example 1 (1) 1 mol of methyl allyl polyoxyethylene ether (molecular weight 2400) was added to a reaction bottle equipped with a stirring and dropping device, and a certain amount of deionized water was added to prepare a base solution with a concentration of 50 wt.%, the stirring was turned on, and the temperature was raised to 50 ° C to obtain a preheated base solution; acrylic acid, 2-aminoethyl methacrylate hydrochloride, methyl allyl carbonate, mercaptoethanol, vitamin C, ethanol and a certain amount of deionized water were prepared to prepare a solution A with a concentration of 30 wt.%, and a certain amount of deionized water was added to the initiator Na2O2 to prepare a solution B with a concentration of 2 wt.%; wherein, methyl allyl polyoxyethylene ether The molar ratio of vinyl ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride is 1:3.0:0.6:0.2, the amount of Na2O2 is 1.5% of the total mass of methyl allyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride, the mass ratio of vitamin C and Na2O2 is 0.8:1, the amount of mercaptoethanol is 0.8% of the total mass of methyl allyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride, and the mass ratio of allyl methyl carbonate and ethanol is 1:1; (2) Solution A and solution B were simultaneously added dropwise to the base solution preheated at 50°C for reaction at 50°C. Solution A was added at a constant speed of 2.5 hours, and solution B was added at a constant speed of 3.0 hours. After the addition of solution B was completed, the reaction was continued at 50°C for 1.0 hour, and then the temperature was lowered to below 30°C. Triethanolamine was added to adjust the pH to 7.0, and then deionized water was added for dilution to obtain a polycarboxylic acid water reducer S1 with a solid content of 40 wt.%.

[0036] Example 2 (1) 1 mol of isopentyl polyoxyethylene ether (molecular weight 2400) was added to a reaction flask equipped with a stirring and dropping device, and a certain amount of deionized water was added to prepare a base solution with a concentration of 52 wt.%, the stirring was turned on, and the temperature was raised to 45 ° C to obtain a preheated base solution; acrylic acid, 2-aminoethyl methacrylate hydrochloride, allyl methyl carbonate, mercaptopropionic acid, vitamin C, ethanol and a certain amount of deionized water were prepared into a solution A with a concentration of 35 wt.%, and a certain amount of deionized water was added to the initiator ammonium persulfate to prepare a solution B with a concentration of 1.5 wt.%; wherein, the molar ratio of isopentyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride was 1:4.0: 0.8:0.5, the amount of ammonium persulfate is 1.0% of the total mass of isopentenyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride, the mass ratio of vitamin C to ammonium persulfate is 1:1, the amount of mercaptopropionic acid is 1.3% of the total mass of isopentenyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride, and the mass ratio of allyl methyl carbonate to ethanol is 1:2; (2) Solution A and solution B were simultaneously added dropwise to the base solution preheated at 45°C and reacted at 45°C. Solution A was added at a uniform rate of 2.0 hours, and solution B was added at a uniform rate of 2.5 hours. After the addition of solution B was completed, the reaction was continued at 45°C for 1.5 hours, and then the temperature was lowered to below 30°C. Diethanolamine was added to adjust the pH to 8.0, and then deionized water was added for dilution to obtain a polycarboxylic acid water reducer S2 with a solid content of 35 wt.%.

[0037] Example 3 (1) 1 mol of methyl allyl polyoxyethylene ether (molecular weight 3000) was added to a reaction bottle equipped with a stirring and dropping device, and a certain amount of deionized water was added to prepare a base solution with a concentration of 55 wt.%, the stirring was turned on, and the temperature was raised to 40 ° C to obtain a preheated base solution; acrylic acid, 2-aminoethyl methacrylate hydrochloride, methyl allyl carbonate, mercaptoethanol, NaHSO3, ethanol and a certain amount of deionized water were prepared to prepare a solution A with a concentration of 40 wt.%, and a certain amount of deionized water was added to the initiator H2O2 to prepare a solution B with a concentration of 1 wt.%; wherein, methyl allyl polyoxyethylene ether The molar ratio of vinyl ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride is 1:3.5:0.5:0.3, the amount of H2O2 is 2.0% of the total mass of methyl allyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride, the mass ratio of NaHSO3 to H2O2 is 0.6:1, the amount of mercaptoethanol is 2% of the total mass of methyl allyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride, and the mass ratio of allyl methyl carbonate to ethanol is 1:1.2; (2) Solution A and solution B were simultaneously added dropwise to the base solution preheated at 40°C for reaction at 40°C. Solution A was added at a uniform rate of 3.0 h, and solution B was added at a uniform rate of 3.5 h. After the addition of solution B was completed, the reaction was continued at 40°C for 2.0 h. The temperature was lowered to below 30°C, triethanolamine was added to adjust the pH to 7.5, and deionized water was added for dilution to obtain a polycarboxylic acid water reducer S3 with a solid content of 38 wt.%.

[0038] Comparative Example 1 Without adding allyl methyl carbonate, the other steps were the same as in Example 1 to obtain a polycarboxylate water-reducing agent PC1 with a solid content of 40 wt.%.

[0039] Comparative Example 2 Without adding 2-aminoethyl methacrylate hydrochloride, the other steps were the same as in Example 1 to obtain a polycarboxylate water-reducing agent PC2 with a solid content of 40 wt.%.

[0040] Comparative Example 3 Triethanolamine was replaced with sodium hydroxide, and the other steps were the same as in Example 1 to obtain a polycarboxylate water-reducing agent PC3 with a solid content of 40 wt.%.

[0041] Concrete performance testing was conducted according to GB8076-2008. Baseline cement was used, and sand was selected from Zone II medium sand with a fineness modulus of 2.7 and a mud content of 0.5%. Gravel was crushed stone with a nominal particle size of 5-20 mm, using a two-stage grading (40% 5-10 mm, 60% 10-20 mm), meeting continuous grading requirements. The base concrete mix ratio was cement: sand: gravel: water = 360:855:965:230. The polycarboxylate superplasticizer content was 0.5% of the cement weight. Concrete incorporating the polycarboxylate superplasticizers of Examples 1-3 and Comparative Examples 1-3 was tested. The results are shown in Table 1.

[0042]

[0043] As can be seen from Table 1, the polycarboxylate water-reducing agents prepared in Examples 1-3 are superior to those in Comparative Examples 1-3 in terms of water reduction rate, slump retention performance, strength development, impermeability and crack resistance and self-healing performance.

[0044] Comparison between S1 and PC1: PC1 lacks allyl methyl carbonate, resulting in a water seepage height of 21.8 mm (S1 is only 15.0 mm), and the number of cracks is 7 / m 2 , the crack area is 13mm 2 / m 2 , the anti-crack self-healing performance is poor.

[0045] Comparison between S1 and PC2: Although PC2 contains allyl methyl carbonate and triethanolamine, it lacks 2-aminoethyl methacrylate hydrochloride, resulting in a water seepage height of up to 21.2 mm and a cracking streak number of 4 / m 2 This indicates that even if PC2 can release carbonate, it lacks the amino group provided by the 2-aminoethyl methacrylate hydrochloride side chain to complex and enrich Ca 2+ It also guides CaCO3 to "precisely" nucleate and deposit at the crack tip. These randomly generated precipitates cannot effectively repair the cracks, resulting in low healing efficiency.

[0046] Comparison between S1 and PC3: PC3 only uses NaOH to adjust pH and lacks the long-term sustained release mechanism of triethanolamine, resulting in a water seepage height of up to 20.6 mm and a cracking stripe count of 2 / m 2 , but still inferior to the performance indicators of S1 (water seepage height 15.0mm, cracking stripe number 1 / m 2 ). It can be seen that the organic alcohol amine-CO2 complex formed by the reaction of organic alcohol amine and CO2 can continuously provide CO2 in the later stage, which can promote the densification of the matrix and enhance the impermeability.

Claims

1. A polycarboxylate water reducer, characterized in that The invention is prepared from unsaturated polyether macromonomer, unsaturated acid monomer, unsaturated carbonate monomer, unsaturated amine monomer, initiator, reducing agent, chain transfer agent, deionized water, solubilizer and organic alcoholamine; wherein the unsaturated carbonate monomer is allyl methyl carbonate, and the unsaturated amine monomer is 2-aminoethyl methacrylate hydrochloride.

2. The polycarboxylate water reducer according to claim 1, characterized in that The unsaturated polyether macromonomer is isopentenyl polyoxyethylene ether or methallyl polyoxyethylene ether; The structural formula of isopentenyl polyoxyethylene ether is as follows: Where n1 is 25-100; The structural formula of methyl allyl polyoxyethylene ether is as follows: Where n1 is 25-100.

3. The polycarboxylate water reducer according to claim 1, characterized in that The unsaturated acid monomer is acrylic acid, and the molar ratio of the unsaturated polyether macromonomer, the unsaturated acid monomer, the unsaturated carbonate monomer and the unsaturated amino monomer is 1:3-4:0.5-0.8:0.2-0.

5.

4. The polycarboxylate water reducer according to claim 1, characterized in that The initiator is one of ammonium persulfate, hydrogen peroxide or sodium peroxide, and the amount of the initiator is 1-2 wt.% of the total mass of the unsaturated polyether macromonomer, the unsaturated acid monomer, the unsaturated carbonate monomer and the unsaturated amino monomer.

5. The polycarboxylate water reducer according to claim 1, characterized in that The reducing agent is vitamin C or sodium bisulfite, and the mass ratio of the initiator to the reducing agent is 1:0.6-1.

0.

6. The polycarboxylate water reducer according to claim 1, characterized in that The chain transfer agent is mercaptoethanol or mercaptopropionic acid, and the amount of the chain transfer agent is 0.8-2.0% of the total mass of the unsaturated polyether macromonomer, the unsaturated acid monomer, the unsaturated carbonate monomer and the unsaturated amino monomer; the solubilizer is ethanol, and the mass ratio of the unsaturated carbonate monomer to the solubilizer is 1:1-2.

7. The polycarboxylate water reducer according to claim 1, characterized in that The organic alcoholamine is diethanolamine or triethanolamine.

8. A method for preparing the polycarboxylate water-reducing agent according to any one of claims 1 to 7, characterized in that The steps include: (1) Unsaturated polyether macromonomer and deionized water are prepared into a base liquid, and heated to obtain a preheated base liquid; unsaturated acid monomer, unsaturated carbonate monomer, unsaturated amine monomer, reducing agent, chain transfer agent, solubilizer and deionized water are prepared into solution A; initiator and deionized water are prepared into solution B; (2) Solution A and solution B are simultaneously added dropwise to the preheated base solution for reaction. After the addition is completed, the reaction is continued at a temperature of 100 °C. The temperature is lowered, an organic alcohol amine is added to adjust the pH value, and deionized water is added for dilution to obtain a polycarboxylic acid water reducer.

9. The method for preparing a polycarboxylate water-reducing agent according to claim 8, wherein In step (1), the concentration of the bottom solution is 50-55 wt.%, which is heated to 40-50°C, the concentration of solution A is 30-40 wt.%, and the concentration of solution B is 1.0-2.0 wt.%.

10. The method for preparing a polycarboxylate water-reducing agent according to claim 8, characterized in that In step (2), the addition time of solution A is 2.0-3.0h, the addition time of solution B is 2.5-3.5h, the reaction temperature is 40-50°C, the insulation reaction time is 1.0-2.0h, the insulation reaction temperature is 40-50°C, the temperature is lowered to below 30°C, the pH value is adjusted to 7.0-8.0, and the solid content of the polycarboxylate water reducer is 35-40wt.%.

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