Polycarboxylic acid water reducing agent and method for preparing the same

Abstract

This invention belongs to the field of concrete technology, specifically relating to a polycarboxylate superplasticizer and its preparation method. The polycarboxylate superplasticizer is composed of unsaturated polyether macromonomers, unsaturated acid monomers, unsaturated carbonate monomers, unsaturated amine monomers, initiators, reducing agents, chain transfer agents, deionized water, solubilizers, and organic alcohol amines; wherein the unsaturated carbonate monomer is allyl methyl carbonate, and the unsaturated amine monomer is 2-aminoethyl methacrylate hydrochloride. This invention not only maintains excellent water-reducing effects and stable control over concrete slump, 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.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, specifically relating to a polycarboxylate superplasticizer and its preparation method. Background Technology

[0002] Concrete, as the primary engineering material created by humankind, is the most widely used building material, found in various engineering projects such as roads, bridges, water conservancy, tunnels, and nuclear power plants. Cracks are inherently present in concrete due to drying shrinkage, plastic shrinkage, and temperature variations. The appearance of cracks reduces the durability of buildings, accelerates the corrosion of reinforcing steel, and seriously affects the service life of structures, especially for century-old projects like bridges, where the presence of cracks poses a greater threat. Globally, crack control has become a key issue in improving the safety and economic efficiency of concrete structures.

[0003] Traditional methods for controlling concrete cracks rely heavily on external repairs and regular maintenance. This is costly, and the repair effectiveness is easily affected by construction quality and environmental conditions, making it difficult to achieve proactive and long-term self-healing. In recent years, self-healing concrete technology has emerged. Chinese patent CN119409453A discloses a self-healing high-toughness concrete and its preparation method. It primarily achieves self-repair of cracked concrete by over-producing a precursor of cementitious materials, and combines this with hybrid fibers to enhance the concrete's toughness. This results in a low-cost, integrated self-healing concrete that combines control and repair. However, this method requires external moisture penetration, and its self-healing effect on concrete cracks is not good in dry environments. Furthermore, the multi-fiber mix used also suffers from difficulties in dispersion and clumping. Chinese patent CN117209208A discloses a method for preparing a self-healing rigid waterproof material for concrete, using cementitious substrate, silica powder, polymer modifier, steel fiber, magnesium oxide microcapsule self-healing agent, and waterproofing additives. However, the problem with this method is that the expansion of magnesium oxide in the magnesium oxide microcapsule self-healing agent is uncontrollable, which may lead to the risk of the concrete cracking 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 micro-cracks in concrete, achieving the repair of concrete cracks; however, this method has high requirements for construction technology and has a significant impact on the workability of the concrete. Summary of the Invention

[0004] The purpose of this invention is to provide a polycarboxylate superplasticizer that not only maintains excellent water-reducing effect and stable control over concrete slump, 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. This invention also provides a method for preparing the polycarboxylate superplasticizer.

[0005] The polycarboxylate superplasticizer of the present invention is made of unsaturated polyether macromonomer, unsaturated acid monomer, unsaturated carbonate monomer, unsaturated amine monomer, initiator, reducing agent, chain transfer agent, deionized water, solubilizer and organic alcohol amine; wherein the unsaturated carbonate monomer is methyl allyl carbonate and the unsaturated amine monomer is 2-aminoethyl methacrylate hydrochloride.

[0006] The unsaturated polyether macromonomers are isopentenyl polyoxyethylene ether or methyl allyl polyoxyethylene ether;

[0007] The structural formula of isopentenyl polyoxyethylene ether is as follows:

[0008]

[0009] In the formula, n1 is 25-100;

[0010] The structural formula of methyl allyl polyoxyethylene ether is as follows:

[0011]

[0012] In the formula, n1 is 25-100.

[0013] The unsaturated acid monomer is acrylic acid, and the molar ratio of unsaturated polyether macromonomer, unsaturated acid monomer, unsaturated carbonate monomer and unsaturated amine monomer is 1:3-4:0.5-0.8:0.2-0.5.

[0014] The initiator is one of ammonium persulfate, hydrogen peroxide or sodium peroxide, and the amount of initiator is 1-2 wt. of the total mass of unsaturated polyether macromonomer, unsaturated acid monomer, unsaturated carbonate monomer and unsaturated amine monomer.

[0015] The reducing agent is vitamin C or sodium bisulfite, and the mass ratio of initiator to reducing agent is 1:0.6-1.0.

[0016] The chain transfer agent is mercaptoethanol or mercaptopropionic acid, and the amount of chain transfer agent used is 0.8-2.0% of the total mass of unsaturated polyether macromonomer, unsaturated acid monomer, unsaturated carbonate monomer and unsaturated amine monomer; the solubilizer is ethanol, and the mass ratio of unsaturated carbonate monomer to solubilizer is 1:1-2.

[0017] The organic alcohol amine is diethanolamine or triethanolamine.

[0018] The preparation method of the polycarboxylate superplasticizer of the present invention includes the following steps:

[0019] (1) Prepare a base liquid by mixing unsaturated polyether macromonomer and deionized water, and heat it to obtain a preheated base liquid; prepare solution A by mixing unsaturated acid monomer, unsaturated carbonate monomer, unsaturated amine monomer, reducing agent, chain transfer agent, solubilizer and deionized water, and prepare solution B by mixing initiator and deionized water.

[0020] (2) Add solutions A and B dropwise to the preheated base liquid at the same time to react. After the addition is complete, continue to keep the reaction warm, cool down, add organic alcohol amine to adjust the pH value, add deionized water to dilute, and obtain polycarboxylate superplasticizer.

[0021] In step (1), the concentration of the base liquid is 50-55 wt.%, heated to 40-50℃, the concentration of solution A is 30-40 wt.%, and the concentration of solution B is 1.0-2.0 wt.%.

[0022] In step (2), the dropwise addition time of solution A is 2.0-3.0 h, the dropwise addition time of solution B is 2.5-3.5 h, the reaction temperature is 40-50℃, the reaction is continued to be kept at the temperature for 1.0-2.0 h, the reaction is continued to be kept at the temperature for 40-50℃, the temperature is lowered to below 30℃, the pH value is adjusted to 7.0-8.0, and the solid content of polycarboxylate superplasticizer is 35-40 wt.%.

[0023] When the polycarboxylate superplasticizer of the present invention is applied to concrete, the dosage of the polycarboxylate superplasticizer is 0.2-0.5% of the weight of the concrete cementitious material.

[0024] This invention provides a polycarboxylate superplasticizer for promoting the self-healing of concrete cracks. This polycarboxylate superplasticizer is simple to prepare, has high repair efficiency, and does not affect the original mechanical properties of the material. This invention introduces controllably released carbonate functional groups into the traditional polycarboxylate molecular chain. When the polycarboxylate superplasticizer disperses with cement in water, the carbonate groups are gradually released in the highly alkaline environment of the concrete, reacting with Ca in the cementitious materials. 2+ The ionic reaction generates stable calcium carbonate precipitates. These precipitates can not only precipitate and fill the micropores on the surface and inside of concrete, but also concentrate and deposit at the tips of microcracks to form a "self-generated" repair body, thereby sealing cracks and capillaries and achieving efficient automatic repair of concrete.

[0025] This invention achieves molecular-level functional coupling by introducing allyl methyl carbonate, 2-aminoethyl methacrylate hydrochloride, and organic alcohol amines into the polycarboxylic acid backbone.

[0026] 1. Targeted transport and in-situ localization

[0027] The carboxyl groups carried by the polycarboxylic acid backbone can be firmly adsorbed onto the cement stone surface. Therefore, the polycarboxylic acid backbone, together with the side chains of allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride, can be anchored in the interfacial transition zone, ensuring that the self-healing active components such as allyl methyl carbonate can play their role in situ at the location that needs to be repaired.

[0028] 2. Continuous release pathway

[0029] The polycarboxylate superplasticizer of this invention, through its unique intramolecular structure formed by copolymerization, can achieve sustained release of carbonate ions, providing concrete with long-lasting self-healing ability. Its specific mechanism is as follows:

[0030] In the polymer molecular chain of the present invention, some methyl allyl 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 amine (-NH2) groups, which can interact with water molecules through hydrogen bonds to construct a local hydrophilic microenvironment around the methyl allyl carbonate side chains.

[0031] When the side chain of methyl allyl carbonate is partially or completely coated by this hydrophilic microenvironment, its hydrolysis behavior is regulated by the following two synergistic effects:

[0032] (1) Spatial hindrance shielding and local environmental buffering: The hydrophilic microenvironment forms an effective steric hindrance shield for the ester bond of methyl carbonate, reducing the frequency of attack by high concentrations of 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 that in the external concrete pore solution, thereby jointly delaying the hydrolysis rate of the ester bond.

[0033] (2) Stable structure of “quasi-complex” formed by intermolecular interaction: The lone pair electrons of the amino group on the side chain of the 2-aminoethyl methacrylate hydrochloride can form hydrogen bonds or dipole-dipole interactions with the oxygen atom in the carbonyl group or ether bond on the side chain of methyl carbonate to form a dynamic and stable non-covalent “quasi-complex” structure; the existence of this structure further stabilizes the chemical properties of the methyl carbonate side chain and reduces its activity in hydrolysis reaction.

[0034] In summary, through the aforementioned synergistic effect, the portion of the methyl carbonate allyl ester side chain affected by the 2-aminoethyl methacrylate hydrochloride side chain can release carbonate ions in a more gradual and sustained manner, thereby forming a continuous slow-release repair channel for long-term concrete damage.

[0035] 3. High-density nucleation and accelerated growth

[0036] In the copolymer structure of this invention, the amino groups on adjacent 2-aminoethyl methacrylate hydrochloride side chains p-Ca 2+ It has excellent coordination ability, which can bind free Ca 2+ Enrichment to the crack interface; enriched Ca 2+ CO3 released with the same chain 2- Close coupling at the molecular scale significantly improves the density and growth rate of CaCO3 crystal nuclei.

[0037] 4. Performance Improvement

[0038] The hydrophilic groups (amine groups) on 2-aminoethyl methacrylate hydrochloride enhance the dispersion stability of the polycarboxylate superplasticizer (PCE) macromolecule in high ionic strength environments. Concrete pore solution is a complex electrolyte solution with high ion concentration (rich in Ca). 2+ Na + K + SO4 2- (etc.). In such solutions, the negative charge (carboxyl group) on the PCE backbone is "shielded" by cations, causing the molecular chain to coil and the comb-like side chains to collapse, thus losing its steric dispersion ability. However, the -NH2 group on 2-aminoethyl methacrylate hydrochloride can form strong hydrogen bonds with water molecules, forming a stable hydration layer around the PCE molecule. This hydration layer acts like a "protective coat," physically preventing the collapse of the side chains and the aggregation of molecules, allowing PCE to maintain its extended conformation even in a high-ionic environment, thereby maintaining its dispersion stability.

[0039] Improving water reduction efficiency: The water reduction efficiency depends on the dispersion ability of PCE molecules on cement particles. As mentioned above, the hydrophilic groups on 2-aminoethyl methacrylate hydrochloride maximize the steric hindrance effect of PCE molecules by maintaining the extended conformation of PCE molecules. Stronger steric hindrance means more efficient dispersion, thus requiring less water to achieve the same fluidity, i.e., higher water reduction efficiency.

[0040] Improved slump retention: Slump retention refers to the ability of a slurry to maintain its 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 down the rate at which PCE molecules are encapsulated or adsorbed by cement products undergoing hydration. This allows more PCE molecules to remain active for a longer period, continuously dispersing cement particles and thus prolonging the fluidity of the slurry, resulting in superior slump retention.

[0041] 5. The organic alcohol amine in this invention constitutes a second long-term sustained-release mechanism. The basic amine group of the organic alcohol amine can capture carbon dioxide dissolved in the pore solution (the carbon dioxide dissolved in the pore solution comes from the atmosphere and is obtained from the reversible reaction of carbonate ions in water) and undergo a reversible reaction to generate a stable organic alcohol amine-CO2 complex, which acts as a "molecular reservoir" of CO2 in the system. The process of the organic alcohol amine-CO2 complex releasing the stored CO2 is driven by a healing reaction: when the process of generating CaCO3 precipitate consumes carbonate ions in the pore solution, it will break the chemical equilibrium. According to the principle of equilibrium shift, the organic alcohol amine-CO2 complex decomposes accordingly, releasing the stored CO2 to replenish the consumed carbonate ions. This process forms an adaptive system that can respond to internal damage and supply repair materials on demand, thereby effectively repairing late-stage cracks and ensuring the long-term self-healing ability of concrete.

[0042] In summary, this invention uses chemical copolymerization to fix allyl methyl carbonate, 2-aminoethyl methacrylate hydrochloride, and organic alcohol amine onto the same polymer backbone, thereby constructing a multi-level synergistic self-healing system.

[0043] The polycarboxylate superplasticizer of the present invention introduces biodegradable 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 <10%, ensuring that rheology and strength are not affected; (2) early hardening stage (3h-6 days, pH≥13): ester bond hydrolysis of carbonate, cumulative release of 30–60% CO3. 2- , reacts with Ca(OH)2 to generate CaCO3; (3) in the middle and late stages of hardening (7-28d): the organic alcohol amine-CO2 complex is slowly decomposed, and together with the remaining carbonate, it releases a cumulative amount of >80% CO3. 2- -NH2 can react with Ca 2+ Coordination accelerates CaCO3 nucleation in cracks or capillaries; -NH2 enhances the hydrophilicity and dispersion stability of side chains; the organic alcohol amine-CO2 complex continuously releases CO2 in the later stages, synergistically with carbonate hydrolysis, resulting in higher self-healing efficiency. 2- Preferential deposition at the crack tip forms microneedle-plate CaCO3 crystals, which fill and seal the channel.

[0044] The beneficial effects of this invention are as follows:

[0045] (1) Dual carbonate release mechanism: The synergistic effect of carbonate hydrolysis and organic alcohol amine-CO2 complex decomposition not only generates carbonate continuously and controllably in a high-alkaline environment, but also achieves discontinuous release, meeting the different needs of early construction and later self-healing.

[0046] (2) Excellent CaCO3 nucleation and distribution: -NH2 side chain can react with Ca 2+ Coordination accelerates the nucleation of CaCO3 in capillaries and microcracks; organic alcohol amines react with CO2 dissolved in the pore solution, stabilizing the pH of the system in the weakly alkaline range, allowing CaCO3 to form. 2+ CO3 2- The more uniform and finer the binding rate and precipitate morphology, the better the early strength and the second source of carbonate for later self-healing.

[0047] (3) Simple and efficient industrial preparation: The use of redox initiation system significantly improves initiation efficiency and polymerization yield. The reaction conditions are mild and energy consumption is low, making it suitable for large-scale production and on-site construction applications. Detailed Implementation

[0048] The present invention will be further described below with reference to embodiments.

[0049] Example 1

[0050] (1) Add 1 mol of methyl allyl polyoxyethylene ether (molecular weight 2400) to a reaction flask equipped with a stirring and dropping device, and add a certain amount of deionized water to prepare a bottom solution with a concentration of 50 wt.%. Turn on the stirring and heat to 50°C to obtain a preheated bottom solution; prepare a solution A with a concentration of 30 wt.% by adding acrylic acid, 2-aminoethyl methacrylate hydrochloride, methyl allyl carbonate, mercaptoethanol, vitamin C, ethanol and a certain amount of deionized water, and prepare a solution B with a concentration of 2 wt.% by adding a certain amount of deionized water to the initiator Na2O2; wherein, methyl allyl polyoxyethylene ether The molar ratio of vinyl ether, acrylic acid, allyl methyl carbonate, and 2-aminoethyl methyl acrylate hydrochloride is 1:3.0:0.6:0.2; the amount of Na2O2 used is 1.5% of the total mass of allyl methyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate, and 2-aminoethyl methyl acrylate hydrochloride; the mass ratio of vitamin C to Na2O2 is 0.8:1; the amount of mercaptoethanol used is 0.8% of the total mass of allyl methyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate, and 2-aminoethyl methyl acrylate hydrochloride; and the mass ratio of allyl methyl carbonate to ethanol is 1:1.

[0051] (2) Solution A and solution B were simultaneously added dropwise to the preheated base liquid at 50°C and reacted at 50°C. Solution A was added dropwise at a uniform rate for 2.5 hours, and solution B was added dropwise at a uniform rate for 3.0 hours. After solution B was added, the reaction was continued at 50°C for 1.0 hour. The temperature was then lowered to below 30°C, and triethanolamine was added to adjust the pH to 7.0. Deionized water was then added for dilution to obtain polycarboxylate superplasticizer S1 with a solid content of 40 wt.%.

[0052] Example 2

[0053] (1) Add 1 mol of isopentenyl polyoxyethylene ether (molecular weight 2400) to a reaction flask equipped with a stirring and dropping device, and add a certain amount of deionized water to prepare a bottom solution with a concentration of 52 wt.%. Turn on the stirring and heat to 45°C to obtain a preheated bottom solution; prepare a solution A with a concentration of 35 wt.% by adding acrylic acid, 2-aminoethyl methacrylate hydrochloride, allyl methyl carbonate, mercaptopropionic acid, vitamin C, ethanol and a certain amount of deionized water; prepare a solution B with a concentration of 1.5 wt.% by adding a certain amount of deionized water to the initiator ammonium persulfate; wherein the molar ratio of isopentenyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate and 2-aminoethyl methacrylate hydrochloride is 1:4.0: The ratio of ammonium persulfate to vitamin C is 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 methyl acrylate 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 methyl acrylate hydrochloride, and the mass ratio of allyl methyl carbonate and ethanol is 1:2.

[0054] (2) Solution A and solution B were simultaneously added dropwise to the preheated base liquid at 45°C and reacted at 45°C. Solution A was added dropwise at a uniform rate for 2.0 h, and solution B was added dropwise at a uniform rate for 2.5 h. After solution B was added, the reaction was continued at 45°C for 1.5 h. The temperature was then lowered to below 30°C, and diethanolamine was added to adjust the pH to 8.0. Deionized water was then added for dilution to obtain polycarboxylate superplasticizer S2 with a solid content of 35 wt.%.

[0055] Example 3

[0056] (1) Add 1 mol of methyl allyl polyoxyethylene ether (molecular weight 3000) to a reaction flask equipped with a stirring and dropping device, and add a certain amount of deionized water to prepare a bottom solution with a concentration of 55 wt.%. Turn on the stirring and heat to 40°C to obtain a preheated bottom solution; prepare a solution A with a concentration of 40 wt.% by adding acrylic acid, 2-aminoethyl methacrylate hydrochloride, methyl allyl carbonate, mercaptoethanol, NaHSO3, ethanol and a certain amount of deionized water, and prepare a solution B with a concentration of 1 wt.% by adding a certain amount of deionized water to the initiator H2O2; wherein, methyl allyl polyoxyethylene ether The molar ratio of vinyl ether, acrylic acid, allyl methyl carbonate, and 2-aminoethyl methyl acrylate hydrochloride is 1:3.5:0.5:0.3; the amount of H2O2 used is 2.0% of the total mass of allyl methyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate, and 2-aminoethyl methyl acrylate hydrochloride; the mass ratio of NaHSO3 to H2O2 is 0.6:1; the amount of mercaptoethanol used is 2% of the total mass of allyl methyl polyoxyethylene ether, acrylic acid, allyl methyl carbonate, and 2-aminoethyl methyl acrylate hydrochloride; and the mass ratio of allyl methyl carbonate to ethanol is 1:1.2.

[0057] (2) Solution A and solution B were simultaneously added dropwise to the preheated base liquid at 40°C and reacted at 40°C. Solution A was added dropwise at a uniform rate for 3.0 h, and solution B was added dropwise at a uniform rate for 3.5 h. After solution B was added, the reaction was continued at 40°C for 2.0 h. The temperature was then lowered to below 30°C, and triethanolamine was added to adjust the pH to 7.5. Deionized water was then added for dilution to obtain polycarboxylate superplasticizer S3 with a solid content of 38 wt.%.

[0058] Comparative Example 1

[0059] Without adding allyl methyl carbonate, the other steps are the same as in Example 1, to obtain polycarboxylate superplasticizer PC1 with a solid content of 40 wt.%.

[0060] Comparative Example 2

[0061] Without adding 2-aminoethyl methacrylate hydrochloride, the other steps are the same as in Example 1, to obtain polycarboxylate superplasticizer PC2 with a solid content of 40 wt.%.

[0062] Comparative Example 3

[0063] By replacing triethanolamine with sodium hydroxide and following the same steps as in Example 1, a polycarboxylate superplasticizer PC3 with a solid content of 40 wt.% was obtained.

[0064] Concrete performance was tested according to GB8076-2008 standard. Reference cement was used, and zone II medium sand with a fineness modulus of 2.7 and a mud content of 0.5% was selected. The aggregate was crushed stone with a nominal particle size of 5-20mm, using a two-stage mix design (40% 5-10mm and 60% 10-20mm), meeting the requirements for continuous gradation. The mix proportion of the reference concrete was cement:sand:aggregate:water = 360:855:965:230, and the polycarboxylate superplasticizer dosage was 0.5% of the cement weight. Concrete with polycarboxylate superplasticizers added in Examples 1-3 and Comparative Examples 1-3 were tested, and the results are shown in Table 1.

[0065]

[0066] As shown in Table 1, the polycarboxylate superplasticizers prepared in Examples 1-3 are superior to those in Comparative Examples 1-3 in terms of water reduction rate, slump retention, strength development, impermeability, and crack resistance and self-healing properties.

[0067] Comparison between S1 and PC1: PC1, lacking allyl methyl carbonate, exhibited a water penetration height of 21.8 mm (compared to only 15.0 mm for S1), and a crack count of 7 lines / m. 2 The crack area is 13mm. 2 / m 2 It has poor crack resistance and self-healing properties.

[0068] Comparison of S1 and PC2: Although PC2 contains allyl methyl carbonate and triethanolamine, the lack of 2-aminoethyl methacrylate hydrochloride results in a water penetration height of up to 21.2 mm and a crack count of 4 lines / m. 2 This indicates that even though PC2 can release carbonate ions, the lack of an amino group provided by the 2-aminoethyl methacrylate hydrochloride side chain to complex and enrich Ca is a significant factor. 2+ It guides CaCO3 to nucleate and deposit "precisely" at the tip of the crack. These randomly generated precipitates cannot effectively repair the crack, resulting in low healing efficiency.

[0069] Comparison of S1 and PC3: PC3 only uses NaOH to adjust the pH and lacks the long-lasting slow-release mechanism of triethanolamine, resulting in a seepage height of up to 20.6 mm and 2 cracks / m. 2 It still falls short of the performance specifications of S1 (water seepage height 15.0 mm, crack count 1 line / m). 2 Therefore, it can be seen that the organic alcohol amine-CO2 complex formed by the reaction of organic alcohol amines with CO2 continuously provides CO2 in the later stage, which can promote matrix densification and enhance impermeability.

Claims

1. A polycarboxylate superplasticizer, characterized in that... It is made from unsaturated polyether macromonomers, unsaturated acid monomers, unsaturated carbonate monomers, unsaturated amine monomers, initiators, reducing agents, chain transfer agents, deionized water, solubilizers and organic alcohol amines; wherein the unsaturated carbonate monomer is allyl methyl carbonate and the unsaturated amine monomer is 2-aminoethyl methacrylate hydrochloride. The unsaturated polyether macromonomers are isopentenyl polyoxyethylene ether or methyl allyl polyoxyethylene ether; The structural formula of isopentenyl polyoxyethylene ether is as follows: In the formula, n1 is 25-100; The structural formula of methyl allyl polyoxyethylene ether is as follows: In the formula, n1 is 25-100; The unsaturated acid monomer is acrylic acid, and the molar ratio of the unsaturated polyether macromonomer, unsaturated acid monomer, unsaturated carbonate monomer, and unsaturated amino monomer is 1:3-4:0.5-0.8:0.2-0.5; The organic alcohol amine is diethanolamine or triethanolamine.

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

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

0.

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

5. A method for preparing the polycarboxylate superplasticizer according to any one of claims 1-4, characterized in that... Includes the following steps: (1) Prepare a base liquid by mixing unsaturated polyether macromonomer and deionized water, and heat it to obtain a preheated base liquid; prepare solution A by mixing unsaturated acid monomer, unsaturated carbonate monomer, unsaturated amine monomer, reducing agent, chain transfer agent, solubilizer and deionized water, and prepare solution B by mixing initiator and deionized water. (2) Add solutions A and B dropwise to the preheated base liquid at the same time to react. After the addition is complete, continue to keep the reaction warm, cool down, add organic alcohol amine to adjust the pH value, add deionized water to dilute, and obtain polycarboxylate superplasticizer.

6. The method for preparing the polycarboxylate superplasticizer according to claim 5, characterized in that... In step (1), the concentration of the base liquid is 50-55 wt.%, heated to 40-50℃, the concentration of solution A is 30-40 wt.%, and the concentration of solution B is 1.0-2.0 wt.%.

7. The method for preparing the polycarboxylate superplasticizer according to claim 5, characterized in that... In step (2), the dropwise addition time of solution A is 2.0-3.0 h, the dropwise addition time of solution B is 2.5-3.5 h, the reaction temperature is 40-50℃, the reaction is continued to be kept at the temperature for 1.0-2.0 h, the reaction is continued to be kept at the temperature for 40-50℃, the temperature is lowered to below 30℃, the pH value is adjusted to 7.0-8.0, and the solid content of polycarboxylate superplasticizer is 35-40 wt.%.

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