A copolymeric polycarboxylate superplasticizer, its preparation method, and concrete

Abstract

This application discloses a copolymeric polycarboxylate superplasticizer, its preparation method, and concrete, relating to the field of concrete technology. Its raw material composition includes: esterified monomers, unsaturated polyether monomers, unsaturated carboxylic acids, unsaturated amide monomers, crosslinking agents, chain transfer agents, oxidizing agents, and reducing agents. The esterified monomers are polymerized from unsaturated carboxylic acids and polyol monomers. The esterified monomers and the polyether monomers are crosslinked and copolymerized by the crosslinking agent to form a three-dimensional network structure in the ether-ester copolymeric polycarboxylate superplasticizer. The crosslinking agent includes compounds containing divinyl groups. The hydrophobic interactions and physical entanglement between the long chains of the esterified monomers can form a gel-like dynamic network in aqueous solution. Water molecules are filled and "locked" in the network gaps. After absorbing water, the polymer chains expand, and the network swells to form a gel-like structure, further hindering the free diffusion of water. Therefore, it has lower sensitivity, and its ester groups have a slow-release effect, thus providing slump retention.

Description

Technical Field

[0001] This application relates to the field of concrete technology, and in particular to a copolymer polycarboxylate superplasticizer, its preparation method, and concrete. Background Technology

[0002] Polycarboxylate superplasticizers have become an indispensable component of modern high-performance concrete due to their excellent performance. However, with the continuous advancement of national infrastructure construction, the demand for concrete has surged, the environmental protection control of the cement industry has been continuously strengthened, the cement standard requirements have been relaxed, and the application of limestone powder with poor hydrophilicity and "alternative fuels" with complex composition has become more and more widespread. The supply of high-quality raw materials is insufficient, which leads to coarser cement particles and gaps in gradation, and a slower hydration reaction rate. This results in widespread bleeding in concrete, which in turn produces a large number of appearance quality problems such as watermarks and sand lines. Summary of the Invention

[0003] This application provides a copolymeric polycarboxylate superplasticizer, its preparation method, and concrete. This aims to improve the widespread bleeding phenomenon in concrete and address appearance quality issues such as numerous watermarks and sand streaks.

[0004] In a first aspect, this application provides a copolymeric polycarboxylate superplasticizer, the raw material composition of which includes: esterified monomers, unsaturated polyether monomers, unsaturated carboxylic acids, unsaturated amide monomers, crosslinking agents, chain transfer agents, oxidizing agents, and reducing agents, wherein: The esterified monomer is polymerized from unsaturated carboxylic acids and polyol monomers; The esterified monomer and the polyether monomer are cross-linked and copolymerized by a cross-linking agent to form a three-dimensional network structure of the ether ester copolymer polycarboxylate superplasticizer; The crosslinking agent includes compounds containing divinyl groups.

[0005] Compared to polyether monomers, the hydrophobic interactions and physical entanglement between the long chains of esterified monomers in this application can form a dynamic network similar to a gel in aqueous solution. Water molecules are filled and "locked" in the network gaps. After absorbing water, the polymer chains stretch, and the network expands to form a gel-like structure, further hindering the free diffusion of water. Therefore, the mother liquor synthesized from esterified monomers has lower sensitivity to cement and other adhesives, and its ester groups have a slow-release effect, thus providing slump retention. In addition, the molecular structure of the synthesized water-reducing agent mother liquor forms a network structure under the action of a crosslinking agent, increasing steric hindrance. While improving the water reduction rate of the water-reducing agent, it can limit the exudation of water molecules. The copolymerized polycarboxylate water-reducing agent not only has low sensitivity and slump retention, but also has a strong water retention effect. This is because the synthesized polycarboxylate water-reducing agent mother liquor, under the action of a crosslinking agent, connects multiple originally linear water-reducing agent molecular chains to form a micro-crosslinked three-dimensional network structure. This structure alters its adsorption behavior on the surface of cement particles, effectively increasing the viscosity of the solution within the capillary pores of the cement paste. It also adsorbs some free water through its network space, thus delaying water evaporation and exudation, thereby playing a water-retaining role. Furthermore, after dissolving in water, it forms a thin, viscous, gel-like film structure. Water molecules entering this film structure are strongly constrained, and the interaction forces between water molecules are strengthened, restricting the diffusion and flow of free water.

[0006] Copolymer polycarboxylate superplasticizers contain a large number of hydrophilic groups such as carboxyl and amide groups. After the carboxyl and amide groups dissociate, they combine with water molecules in large quantities through hydrogen bonding to form a dense "hydration film" with a colloidal network structure, thereby locking in water. On the other hand, the carboxyl and amide groups attract cations, and the cation concentration in the network is higher than that in the water, resulting in an ion concentration difference and osmotic pressure between the internal and external solutions, which drives water molecules to diffuse into the polymer and be fixed.

[0007] The crosslinking agent contains divinyl groups, which, under the action of free radical initiators, allow the two highly polymerizable vinyl groups to open simultaneously and covalently bond with the two main polymer chains in the system, thereby introducing a micro-crosslinking structure and transforming the traditional comb-like water-reducing agent molecules into a three-dimensional network structure. Furthermore, the flexible segments in the middle impart a certain degree of flexibility to the network structure, effectively maintaining its integrity.

[0008] In some embodiments, the molecular weight of the unsaturated polyether monomer is 2400-4000. This molecular weight range provides better steric hindrance to the water-reducing agent while inhibiting the entanglement of branched chains, thereby improving its dispersion performance and water reduction rate; and / or, The molecular weight of the polyol monomer is 300~1200; within this range, the polyol monomer can react fully with unsaturated carboxylic acids and is less prone to explosive polymerization, allowing the water-reducing agent molecules to be uniformly adsorbed on the surface of cement particles, thereby improving the cohesiveness of the paste and reducing the likelihood of bleeding and segregation; and / or, The mass ratio of the esterified monomer to the unsaturated polyether monomer is (0.1~1):1. When the esterified monomer and the unsaturated polyether monomer are copolymerized at this mass ratio, the molecular weight of the water-reducing agent is relatively small. When the long and short side chain structures are used in a certain proportion, the water-reducing agent can contain more hydrophilic groups while ensuring its slump retention performance. The molecular structure is also network-like, which can better encapsulate water molecules, enhance the interaction between water molecules, thereby reducing the frequency of free diffusion of water molecules, which is more conducive to preventing the bleeding of free water and improving the water retention performance of concrete.

[0009] In some embodiments, the molar ratio of unsaturated carboxylic acid to polyol monomer during the synthesis of the esterified monomer is (1.5~5):1. Maintaining this molar ratio during synthesis allows for more complete reaction of the polyol monomer, achieving the optimal esterification rate, reducing residual unsaturated carboxylic acid, avoiding interference with subsequent copolymerization reactions, and resulting in a relatively regular structure of the esterified monomer, thus yielding a stable water-reducing agent product.

[0010] In some embodiments, the polyol monomer includes at least one of polyethylene glycol and methoxy polyethylene glycol. Using at least one of the above polyol monomers, esterified with unsaturated carboxylic acids to form an esterified monomer, has a slow-release effect and can improve the compatibility of the water-reducing agent with cement and other adhesives, giving it better low sensitivity and slump retention effects; and / or, The unsaturated carboxylic acid includes at least one selected from acrylic acid, methacrylic acid, and maleic acid. Using at least one of these unsaturated carboxylic acids can provide adsorption sites for the water-reducing agent, enhancing its performance; and / or, The unsaturated polyether monomer includes at least one of methyl allyl polyethylene glycol ether, methyl allyl polyethylene glycol ether, ethylene glycol monovinyl polyethylene glycol ether, and 4-hydroxybutyl vinyl polyoxyethylene ether. Using at least one of the above unsaturated polyether monomers can provide steric hindrance to the water-reducing agent product, thereby giving it a higher water-reducing rate; and / or The unsaturated amide monomer includes at least one of acrylamide, N,N-dimethylacrylamide, and isopropylacrylamide. Using at least one of the above unsaturated amide monomers can provide a slow-release effect and adsorb water molecules for the water-reducing agent, thereby enhancing its slump retention and water retention effects; and / or, The crosslinking agent includes at least one of N,N-methylenebisacrylamide, N,N-vinylbisacrylamide, and ethylene glycol dimethacrylate. These crosslinking agents contain abundant hydrophilic groups, which can form hydrogen bonds with water. Upon contact with water, they can rapidly absorb and store a large amount of water, forming a hydrogel, thereby further locking in moisture. Furthermore, they can give the product a suitable network structure, improving the water-retaining effect of the water-reducing agent; and / or, The chain transfer agent includes at least one selected from sodium hypophosphite, 3-mercaptopropionic acid, mercaptoacetic acid, and mercaptoethanol. Using at least one of the above chain transfer agents can give the product a suitable molecular weight and distribution; and / or, The oxidant includes at least one of hydrogen peroxide, ammonium persulfate, and potassium persulfate. Using at least one of these oxidants allows for a suitable decomposition rate at the reaction temperature, thereby better initiating monomer copolymerization and stably maintaining a suitable copolymerization rate; and / or, The reducing agent includes at least one of vitamin C, sodium formaldehyde sulfoxylate, sodium dioctyl succinate sulfonate, sodium sulfite, and ferrous sulfate heptahydrate. Using at least one of these reducing agents can react with the oxidizing agent to reduce the free energy of monomer copolymerization, thus initiating the reaction more efficiently.

[0011] In some embodiments, the raw materials, by weight parts, include: 200-360 parts of unsaturated polyether monomer, 20-200 parts of esterified monomer, 10-40 parts of unsaturated carboxylic acid, 5-10 parts of unsaturated amide monomer, 1-3 parts of crosslinking agent, 1-5 parts of chain transfer agent, 2-10 parts of oxidizing agent, and 0.5-2 parts of reducing agent. Under this weight ratio, a polycarboxylate superplasticizer product can be obtained by copolymerizing the unsaturated polyether monomer and esterified monomer with unsaturated carboxylic acid and unsaturated amide monomers through a good ratio. Compared with ordinary polycarboxylate superplasticizers, this product has better compatibility with cement and other adhesives, and it has excellent water retention and slump retention properties, which can effectively improve problems such as sand lines and watermarks caused by the high sensitivity of concrete and its tendency to bleed.

[0012] Secondly, this application provides a method for preparing a copolymeric polycarboxylate superplasticizer, comprising the following steps: Unsaturated carboxylic acids and polyol monomers are esterified to obtain esterified monomers; The unsaturated polyether monomer is mixed with the first esterified monomer to obtain the first mixture; The first mixture is mixed with a chain transfer agent, a reducing agent, an oxidizing agent, a crosslinking agent, an unsaturated carboxylic acid, an unsaturated amide monomer, and a second esterification monomer, and then matured to obtain a polycarboxylic acid water-reducing agent.

[0013] By mixing unsaturated polyether monomers with the first part of esterified monomers, and then adding oxidants, crosslinking agents, chain transfer agents, reducing agents, unsaturated carboxylic acid monomers, unsaturated amide monomers, and the second part of esterified monomers stepwise to the first mixture, the unsaturated polyether monomers and esterified monomers can polymerize under the action of oxidants, initiators, and chain transfer agents. The esterified monomers, together with the macromolecular polyether monomers, are crosslinked and copolymerized with unsaturated carboxylic acid monomers and unsaturated amide monomers to form an ether-ester copolymer type polycarboxylic acid superplasticizer. Compared with conventional polycarboxylic acid superplasticizers, the mother liquor synthesized from the esterified monomers is less sensitive to cement and other adhesives, and its ester groups have a slow-release effect, thus providing slump retention. Furthermore, the molecular structure of the synthesized superplasticizer mother liquor forms a network structure under the action of the crosslinking agent, which can restrict the exudation of water molecules. It also contains many hydrophilic groups such as carboxyl and amide groups, which, after dissociation, form a colloidal film network structure with water molecules through hydrogen bonding. This network structure can absorb and store a large amount of water, and has a strong binding force on water molecules and enhances the interaction forces between water molecules.

[0014] In some embodiments, the esterification temperature is 95°C to 125°C. Within this temperature range, the esterification reaction can proceed fully, leading to better polymerization and the desired product; and / or, The esterification time is 5h to 8h. Within this range, the esterification reaction can be carried out fully, thereby improving the product conversion rate.

[0015] In some embodiments, the mixing of the unsaturated polyether monomer with the first portion of the esterified monomer to obtain the first mixture includes: The mixing temperature is 8℃~25℃. Within this range, production can be carried out at room temperature, reducing energy consumption and saving costs; and / or, The mixing time is 0.5h to 3h. Within this range, the monomers can be completely dissolved, allowing for better polymerization and the desired product to be obtained.

[0016] In some embodiments, the first mixture is mixed with a chain transfer agent, a reducing agent, an oxidizing agent, a crosslinking agent, an unsaturated carboxylic acid, an unsaturated amide monomer, and a second esterification monomer, and then matured to obtain a polycarboxylic acid water-reducing agent. The maturation time is 1 to 3 hours.

[0017] Thirdly, this application provides a type of concrete, including the copolymeric polycarboxylate superplasticizer described in the first aspect, or the copolymeric polycarboxylate superplasticizer prepared by the preparation method of the copolymeric polycarboxylate superplasticizer described in the second aspect. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] Polycarboxylate superplasticizers have become an indispensable component of modern high-performance concrete due to their excellent performance. However, with the continuous advancement of national infrastructure construction, the demand for concrete has surged, the environmental protection control of the cement industry has been continuously strengthened, the cement standard requirements have been relaxed, and the application of limestone powder with poor hydrophilicity and "alternative fuels" with complex composition has become more and more widespread. The supply of high-quality raw materials is insufficient, which leads to coarser cement particles and gaps in gradation, and a slower hydration reaction rate. This results in widespread bleeding in concrete, which in turn produces a large number of appearance quality problems such as watermarks and sand lines.

[0020] To address issues such as watermarks and sand lines caused by concrete bleeding, water-retaining additives are commonly used. However, these additives are relatively expensive and can weaken the water-reducing and slump-retaining properties of polycarboxylate superplasticizers. Furthermore, they have poor compatibility with concrete raw materials, directly leading to an increase in the overall cost of superplasticizers.

[0021] For example, the preparation method and application of water-retaining polycarboxylate superplasticizers require, firstly, an oil-in-water emulsion system (i.e., water / palmitic acid, decanoic acid and myristic acid / emulsifier system), and then the oil-in-water emulsion system is subjected to a polymerization reaction to obtain a capsule-type superplasticizer emulsion. This production process and raw materials are relatively complex and difficult to industrialize.

[0022] In view of this, this application provides a copolymeric polycarboxylate superplasticizer, its preparation method, and concrete. This aims to improve the widespread bleeding phenomenon in concrete and address appearance quality issues such as numerous watermarks and sand streaks.

[0023] In a first aspect, this application provides a copolymeric polycarboxylate superplasticizer, the raw material composition of which includes: esterified monomers, unsaturated polyether monomers, unsaturated carboxylic acids, unsaturated amide monomers, crosslinking agents, chain transfer agents, oxidizing agents, and reducing agents, wherein: The esterified monomer is polymerized from unsaturated carboxylic acids and polyol monomers; The esterified monomer and the polyether monomer are cross-linked and copolymerized by a cross-linking agent to form a three-dimensional network structure of the ether ester copolymer polycarboxylate superplasticizer; The crosslinking agent includes compounds containing divinyl groups.

[0024] Compared to polyether monomers, the hydrophobic interactions and physical entanglement between the long chains of esterified monomers in this application can form a dynamic network similar to a gel in aqueous solution. Water molecules are filled and "locked" in the network gaps. After absorbing water, the polymer chains stretch, and the network expands to form a gel-like structure, further hindering the free diffusion of water. Therefore, the mother liquor synthesized from esterified monomers has lower sensitivity to cement and other adhesives, and its ester groups have a slow-release effect, thus providing slump retention. In addition, the molecular structure of the synthesized water-reducing agent mother liquor forms a network structure under the action of a crosslinking agent, increasing steric hindrance. While improving the water reduction rate of the water-reducing agent, it can limit the exudation of water molecules. The copolymerized polycarboxylate water-reducing agent not only has low sensitivity and slump retention, but also has a strong water retention effect. This is because the synthesized polycarboxylate water-reducing agent mother liquor, under the action of a crosslinking agent, connects multiple originally linear water-reducing agent molecular chains to form a micro-crosslinked three-dimensional network structure. This structure alters its adsorption behavior on the surface of cement particles, effectively increasing the viscosity of the solution within the capillary pores of the cement paste. It also adsorbs some free water through its network space, thus delaying water evaporation and exudation, thereby playing a water-retaining role. Furthermore, after dissolving in water, it forms a thin, viscous, gel-like film structure. Water molecules entering this film structure are strongly constrained, and the interaction forces between water molecules are strengthened, restricting the diffusion and flow of free water.

[0025] Copolymer polycarboxylate superplasticizers contain a large number of hydrophilic groups such as carboxyl and amide groups. After the carboxyl and amide groups dissociate, they combine with water molecules in large quantities through hydrogen bonding to form a dense "hydration film" with a colloidal network structure, thereby locking in water. On the other hand, the carboxyl and amide groups attract cations, and the cation concentration in the network is higher than that in the water, resulting in an ion concentration difference and osmotic pressure between the internal and external solutions, which drives water molecules to diffuse into the polymer and be fixed.

[0026] The crosslinking agent contains divinyl groups, which, under the action of free radical initiators, allow the two highly polymerizable vinyl groups to open simultaneously and covalently bond with the two main polymer chains in the system, thereby introducing a micro-crosslinking structure and transforming the traditional comb-like water-reducing agent molecules into a three-dimensional network structure. Furthermore, the flexible segments in the middle impart a certain degree of flexibility to the network structure, effectively maintaining its integrity.

[0027] In conjunction with the first aspect, in some embodiments provided in this application, the molecular weight of the unsaturated polyether monomer is 2400~4000. The molecular weight of the unsaturated polyether monomer is within this range, which can provide better steric hindrance for the water-reducing agent while inhibiting the entanglement of branches, thereby improving its dispersion performance and water reduction rate.

[0028] In conjunction with the first aspect, in some embodiments provided in this application, the molecular weight of the polyol monomer is 300~1200; the molecular weight of the polyol monomer is within this range, which allows it to react fully with unsaturated carboxylic acids and is not prone to explosive polymerization, so that the water-reducing agent molecules are uniformly adsorbed on the surface of cement particles, thereby improving the cohesiveness of the slurry and making it less prone to bleeding and segregation.

[0029] In conjunction with the first aspect, in some embodiments provided in this application, the mass ratio of the esterified monomer to the unsaturated polyether monomer is (0.1~1):1. When the esterified monomer and the unsaturated polyether monomer are copolymerized at this mass ratio, the molecular weight of the water-reducing agent is relatively small. When the long and short side chain structures are used in a certain proportion, it can further increase the amount of hydrophilic groups and make the molecular structure network-like, while ensuring the slump retention performance of the water-reducing agent. This can better encapsulate water molecules, enhance the interaction between water molecules, thereby reducing the free diffusion frequency of water molecules, which is more conducive to preventing the bleeding of free water and improving the water retention performance of concrete.

[0030] In conjunction with the first aspect, in some embodiments provided in this application, the molar ratio of unsaturated carboxylic acid to polyol monomer during the synthesis of the esterified monomer is (1.5~5):1. Maintaining this molar ratio during the synthesis of the esterified monomer allows for a more complete reaction of the polyol monomer, achieving the optimal esterification rate, reducing the residual amount of unsaturated carboxylic acid, avoiding interference with subsequent copolymerization reactions, and resulting in a relatively regular structure of the esterified monomer, thereby obtaining a water-reducing agent product with stable performance.

[0031] In conjunction with the first aspect, in some embodiments provided in this application, the polyol monomer includes at least one of polyethylene glycol and methoxy polyethylene glycol. Using at least one of the above-mentioned polyol monomers to form an esterified monomer by esterification with an unsaturated carboxylic acid has a slow-release effect and can improve the compatibility of water-reducing agents with cement and other adhesives, thus giving them better low sensitivity and slump retention effects.

[0032] In conjunction with the first aspect, in some embodiments provided in this application, the unsaturated carboxylic acid includes at least one of acrylic acid, methacrylic acid and maleic acid. Using at least one of the above unsaturated carboxylic acids can provide adsorption sites for the water-reducing agent and enhance its working performance.

[0033] In conjunction with the first aspect, in some embodiments provided in this application, the unsaturated polyether monomer includes at least one of methyl allyl polyethylene glycol ether, methyl allyl polyethylene glycol ether, ethylene glycol monovinyl polyethylene glycol ether, and 4-hydroxybutyl vinyl polyoxyethylene ether. Using at least one of the above unsaturated polyether monomers can provide steric hindrance to the water-reducing agent product, thereby enabling it to have a higher water reduction rate.

[0034] In conjunction with the first aspect, in some embodiments provided in this application, the unsaturated amide monomer includes at least one of acrylamide, N,N-dimethylacrylamide, and isopropylacrylamide. Using at least one of the above-mentioned unsaturated amide monomers can provide a slow-release effect and adsorb water molecules for the water-reducing agent, thereby enhancing its slump retention and water retention effects.

[0035] In conjunction with the first aspect, in some embodiments provided in this application, the crosslinking agent includes at least one of N,N-methylenebisacrylamide, N,N-vinylbisacrylamide, and ethylene glycol dimethacrylate. These crosslinking agents contain abundant hydrophilic groups, which can form hydrogen bonds with water. When exposed to water, they can quickly absorb and store a large amount of water to form a hydrogel, thereby further locking in moisture. Moreover, they can give the product a suitable network structure and improve the water retention effect of the water-reducing agent.

[0036] In conjunction with the first aspect, in some embodiments provided in this application, the chain transfer agent includes at least one of sodium hypophosphite, 3-mercaptopropionic acid, mercaptoacetic acid, and mercaptoethanol. Using at least one of the above chain transfer agents can make the product have a suitable molecular weight and distribution.

[0037] In conjunction with the first aspect, in some embodiments provided in this application, the oxidant includes at least one of hydrogen peroxide, ammonium persulfate, and potassium persulfate. Using at least one of the above oxidants can achieve a suitable decomposition rate at the reaction temperature, thereby better initiating monomer copolymerization and stably maintaining a suitable copolymerization rate of the monomers.

[0038] In conjunction with the first aspect, in some embodiments provided in this application, the reducing agent includes at least one selected from vitamin C, sodium formaldehyde sulfoxylate, sodium dioctyl succinate sulfonate, sodium sulfite, and ferrous sulfate heptahydrate. Using at least one of the above reducing agents can react with the oxidizing agent to reduce the free energy of monomer copolymerization, thereby initiating the reaction more efficiently.

[0039] In conjunction with the first aspect, in some embodiments provided in this application, the raw materials, by weight parts, include: 200-360 parts of unsaturated polyether monomer, 20-200 parts of esterified monomer, 10-40 parts of unsaturated carboxylic acid, 5-10 parts of unsaturated amide monomer, 1-3 parts of crosslinking agent, 1-5 parts of chain transfer agent, 2-10 parts of oxidizing agent, and 0.5-2 parts of reducing agent. Under this weight ratio, a polycarboxylic acid water-reducing agent product can be obtained by copolymerizing the unsaturated polyether monomer and esterified monomer with unsaturated carboxylic acid and unsaturated amide monomer through a good ratio. Compared with ordinary polycarboxylic acid water-reducing agents, this product has better compatibility with cement and other adhesives, and it has excellent water retention and slump retention properties, which can effectively improve problems such as sand lines and watermarks caused by the high sensitivity of concrete and its tendency to bleed.

[0040] Secondly, this application provides a method for preparing a copolymeric polycarboxylate superplasticizer, comprising the following steps: Unsaturated carboxylic acids and polyol monomers are esterified to obtain esterified monomers; The unsaturated polyether monomer is mixed with the first esterified monomer to obtain the first mixture; The first mixture is mixed with a chain transfer agent, a reducing agent, an oxidizing agent, a crosslinking agent, an unsaturated carboxylic acid, an unsaturated amide monomer, and a second esterification monomer, and then matured to obtain a polycarboxylic acid water-reducing agent.

[0041] By mixing unsaturated polyether monomers with the first part of esterified monomers, and then adding oxidants, crosslinking agents, chain transfer agents, reducing agents, unsaturated carboxylic acid monomers, unsaturated amide monomers, and the second part of esterified monomers stepwise to the first mixture, the unsaturated polyether monomers and esterified monomers can polymerize under the action of oxidants, initiators, and chain transfer agents. The esterified monomers, together with the macromolecular polyether monomers, are crosslinked and copolymerized with unsaturated carboxylic acid monomers and unsaturated amide monomers to form an ether-ester copolymer type polycarboxylic acid superplasticizer. Compared with conventional polycarboxylic acid superplasticizers, the mother liquor synthesized from the esterified monomers is less sensitive to cement and other adhesives, and its ester groups have a slow-release effect, thus providing slump retention. Furthermore, the molecular structure of the synthesized superplasticizer mother liquor forms a network structure under the action of the crosslinking agent, which can restrict the exudation of water molecules. It also contains many hydrophilic groups such as carboxyl and amide groups, which, after dissociation, form a colloidal film network structure with water molecules through hydrogen bonding. This network structure can absorb and store a large amount of water, and has a strong binding force on water molecules and enhances the interaction forces between water molecules.

[0042] In conjunction with the second aspect, in some embodiments provided in this application, the esterification temperature is 95℃~125℃. Within this temperature range, the esterification reaction can proceed fully, resulting in better polymerization and the desired product. The esterification time is 5h~8h. Within this time range, the esterification reaction can proceed fully, improving the product conversion rate.

[0043] In conjunction with the second aspect, in some embodiments provided in this application, the mixing of the unsaturated polyether monomer with the first portion of the esterified monomer to obtain the first mixture involves the following: the mixing temperature is 8°C to 25°C. Within this temperature range, production can be carried out at room temperature, reducing energy consumption and saving costs. The mixing time is 0.5h to 3h. Within this time range, the monomer can be completely dissolved, allowing for better polymerization to obtain the desired product.

[0044] In conjunction with the second aspect, in some embodiments provided in this application, the process of mixing the first mixture with a chain transfer agent, a reducing agent, an oxidizing agent, a crosslinking agent, an unsaturated carboxylic acid, an unsaturated amide monomer, and a second portion of the esterification monomer, followed by aging, yields a polycarboxylic acid water-reducing agent. The curing time is 1 to 3 hours. Within this range, the monomer copolymerization reaction can be more complete, while improving production efficiency, saving energy, and obtaining products with better molecular weight and distribution.

[0045] Thirdly, this application provides a type of concrete, including the copolymeric polycarboxylate superplasticizer described in the first aspect, or the copolymeric polycarboxylate superplasticizer prepared by the preparation method of the copolymeric polycarboxylate superplasticizer described in the second aspect.

[0046] The technical solutions provided in this application will be described in detail below with reference to the embodiments.

[0047] Example 1 Example 1 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: 1) Preparation of esterified monomer: 530 parts of methoxy polyethylene glycol with a molecular weight of 1200 were melted and added to a reaction vessel with 4 parts of concentrated sulfuric acid and 4 parts of hydroquinone. Nitrogen gas was introduced for protection. After heating to 100°C, 64 parts of acrylic acid were added dropwise to the reaction vessel over a period of 4 hours. The mixture was kept at this temperature for 2 hours. After cooling, liquid alkali was slowly added to adjust the pH to 6 and water was added to obtain an esterified monomer with a solid content of 60%.

[0048] 2) Preparation of water-reducing agent: 340 parts of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 3000, 20 parts of the above-mentioned esterified monomer with a solid content of 60% and 320 parts of water are stirred and dissolved at 15°C for 1 hour to obtain the first mixture. Add 3 parts of 1% ferrous sulfate aqueous solution, 3 parts of hydrogen peroxide and 1 part of N,N-methylenebisacrylamide to the first mixture in sequence, and stir for 5 min to obtain the second mixture; The third mixture was prepared by stirring 2 parts mercaptoethanol, 0.5 parts vitamin C, and 60 parts water. 28 parts acrylic acid, 12 parts esterification monomer, 5 parts isopropylacrylamide and 40 parts water were mixed to obtain a fourth mixture; The third and fourth mixtures were added dropwise to the second mixture at 60 min and 50 min times, respectively. After maturation for 1 hour, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0049] Example 2 Example 2 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: 1) Preparation of esterified monomer: 520 parts of methoxy polyethylene glycol with a molecular weight of 1200 were melted and added to a reaction vessel with 5 parts of concentrated sulfuric acid and 3 parts of hydroquinone. Nitrogen gas was introduced for protection. After heating to 120°C, 75 parts of methacrylic acid were added dropwise to the reaction vessel over a period of 3 hours. The mixture was kept at this temperature for 2 hours. After cooling, liquid alkali was slowly added to adjust the pH to 6 and water was added to obtain an esterified monomer with a solid content of 60%.

[0050] 2) Preparation of water-reducing agent: 280 parts of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 3000, 80 parts of the above-mentioned esterified monomer with a solid content of 60% and 250 parts of water are stirred and dissolved at 25°C for 1 h to obtain the first mixture. Add 6 parts hydrogen peroxide and 1 part N,N-methylenebisacrylamide to the first mixture and stir for 5 minutes to obtain the second mixture. The third mixture was prepared by mixing 3 parts mercaptopropionic acid, 0.8 parts sodium dioctyl succinate sulfonate, and 60 parts water. The fourth mixture was prepared by mixing 20 parts acrylic acid, 20 parts esterified monomer, 5 parts N,N-dimethylacrylamide and 40 parts water. The third and fourth mixtures were added dropwise to the second mixture at 60 min and 50 min times, respectively. After maturation for 1 hour, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0051] Example 3 Example 3 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: 1) Preparation of esterified monomer: 530 parts of polyethylene glycol with a molecular weight of 1200 were melted and added to a reaction vessel with 4 parts of concentrated sulfuric acid and 4 parts of hydroquinone. Nitrogen gas was introduced for protection. After heating to 100°C, 64 parts of acrylic acid were added dropwise to the reaction vessel over a period of 4 hours. The mixture was kept at this temperature for 2 hours. After cooling, liquid alkali was slowly added to adjust the pH to 6 and water was added to obtain an esterified monomer with a solid content of 60%.

[0052] 2) Preparation of water-reducing agent: 200 parts of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 3000, 160 parts of the above-mentioned esterified monomer with a solid content of 60% and 200 parts of water are stirred and dissolved at 25°C for 1 h to obtain the first mixture. Add 1 part of 1% ferrous sulfate aqueous solution, 4 parts of sodium hypophosphite, 6 parts of hydrogen peroxide and 3 parts of ethylene glycol dimethacrylate to the first mixture in sequence, and stir for 5 min to obtain the second mixture. Mix 1 part vitamin C and 60 parts water to obtain the third mixture; The fourth mixture was prepared by mixing 25 parts acrylic acid, 15 parts esterified monomer, 5 parts acrylamide and 45 parts water. The third and fourth mixtures were added dropwise to the second mixture at 60 min and 50 min times, respectively. After maturation for 2 h, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0053] Example 4 Example 4 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: 1) Preparation of esterified monomer: 520 parts of polyethylene glycol with a molecular weight of 1200 were melted and added to a reaction vessel along with 5 parts of concentrated sulfuric acid and 3 parts of hydroquinone. Nitrogen gas was introduced for protection. After heating to 120°C, 75 parts of methacrylic acid were added dropwise to the reaction vessel over a period of 3 hours. The mixture was kept at this temperature for 2 hours. After cooling, liquid alkali was slowly added to adjust the pH to 6 and water was added to obtain an esterified monomer with a solid content of 60%.

[0054] 2) Preparation of water-reducing agent: 200 parts of ethylene glycol monovinyl polyethylene glycol ether with a molecular weight of 2400, 170 parts of the above-mentioned esterified monomer with a solid content of 60% and 200 parts of water are stirred and dissolved at 15°C for 1 h to obtain the first mixture. Add 1 part of 1% ferrous sulfate aqueous solution, 5 parts of hydrogen peroxide and 3 parts of N,N-methylenebisacrylamide to the first mixture in sequence, and stir for 5 min to obtain the second mixture; Two parts mercaptopropionic acid, 0.7 parts vitamin C, and 60 parts water were stirred to obtain a third mixture; The fourth mixture was prepared by mixing 30 parts acrylic acid, 10 parts isopropylacrylamide and 40 parts water. The third and fourth mixtures were added dropwise to the second mixture at 60 min and 50 min times, respectively. After maturation for 1 hour, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0055] Example 5 Example 5 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: 1) Preparation of esterified monomer: 420 parts of methoxy polyethylene glycol with a molecular weight of 300 were melted and added to a reaction vessel along with 4 parts of concentrated sulfuric acid and 4 parts of hydroquinone. Nitrogen gas was introduced for protection. After heating to 110°C, 180 parts of methacrylic acid were added dropwise to the reaction vessel over a period of 4 hours. The mixture was kept at this temperature for 2 hours. After cooling, liquid alkali was slowly added to adjust the pH to 6 and water was added to obtain an esterified monomer with a solid content of 60%.

[0056] 2) Preparation of water-reducing agent: 320 parts of methyl allyl polyethylene glycol ether with a molecular weight of 2400, 40 parts of the above esterified monomer with a solid content of 60% and 300 parts of water are stirred and dissolved at 25°C for 1 hour to obtain the first mixture. Add 1 part sodium hypophosphite, 7 parts hydrogen peroxide and 2 parts N,N-methylenebisacrylamide to the first mixture in sequence, and stir for 5 min to obtain the second mixture; A third mixture was prepared by stirring 1 part mercaptoethanol, 0.5 parts vitamin C, 0.3 parts sodium sulfite, and 60 parts water. The fourth mixture was prepared by mixing 25 parts acrylic acid, 18 parts esterification monomer, 10 parts acrylamide and 40 parts water. The third and fourth mixtures were added dropwise to the second mixture at 70 min and 60 min times, respectively. After maturation for 1 hour, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0057] Example 6 Example 6 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: 1) Preparation of esterified monomer: 390 parts of methoxy polyethylene glycol with a molecular weight of 400 were melted and added to a reaction vessel with 5 parts of concentrated sulfuric acid and 5 parts of hydroquinone. Nitrogen gas was introduced for protection. After heating to 100°C, 200 parts of methacrylic acid were added dropwise to the reaction vessel over a period of 4 hours. The mixture was kept at this temperature for 2 hours. After cooling, liquid alkali was slowly added to adjust the pH to 6 and water was added to obtain an esterified monomer with a solid content of 60%.

[0058] 2) Preparation of water-reducing agent: 300 parts of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 3000, 60 parts of the above-mentioned esterified monomer with a solid content of 60% and 320 parts of water are stirred and dissolved at 10°C for 2 h to obtain the first mixture. Add 2 parts of 1% ferrous sulfate aqueous solution, 8 parts of hydrogen peroxide and 1.5 parts of N,N-vinylbisacrylamide to the first mixture in sequence, and stir for 5 min to obtain the second mixture; Mix 2 parts mercaptoacetic acid, 0.5 parts vitamin C, and 60 parts water to obtain a third mixture; Mix 40 parts acrylic acid, 7 parts acrylamide and 40 parts water to obtain the fourth mixture; The third and fourth mixtures were added dropwise to the second mixture at 60 min and 50 min times, respectively. After maturation for 3 h, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0059] Example 7 Example 7 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: 1) Preparation of esterified monomer: 440 parts of methoxy polyethylene glycol with a molecular weight of 1200 were melted and added to a reaction vessel with 5 parts of concentrated sulfuric acid and 4 parts of hydroquinone. Nitrogen gas was introduced for protection. After heating to 100°C, 155 parts of maleic acid were added dropwise to the reaction vessel over a period of 4 hours. The mixture was kept at this temperature for 2 hours. After cooling, liquid alkali was slowly added to adjust the pH to 6 and water was added to obtain an esterified monomer with a solid content of 60%.

[0060] 2) Preparation of water-reducing agent: 200 parts of methyl methacrylate polyethylene glycol ether with a molecular weight of 2400, 150 parts of the above-mentioned esterified monomer with a solid content of 60% and 270 parts of water are stirred and dissolved at 20°C for 1 h to obtain the first mixture. Add 0.5 parts sodium hypophosphite, 4 parts ammonium persulfate, 6 parts hydrogen peroxide and 2 parts ethylene glycol dimethacrylate to the first mixture in sequence, and stir for 5 min to obtain the second mixture; The third mixture is prepared by mixing 2 parts mercaptoethanol, 1 part vitamin C, 1 part sodium sulfite and 60 parts water. The fourth mixture was prepared by mixing 30 parts acrylic acid, 10 parts esterification monomer, 8 parts isopropylacrylamide and 40 parts water. The third and fourth mixtures were added dropwise to the second mixture at 60 min and 50 min times, respectively. After maturation for 1 hour, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0061] Example 8 Example 8 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: 1) Preparation of esterified monomer: 440 parts of methoxy polyethylene glycol with a molecular weight of 1200 were melted and added to a reaction vessel with 5 parts of concentrated sulfuric acid and 4 parts of hydroquinone. Nitrogen gas was introduced for protection. After heating to 100°C, 155 parts of methacrylic acid were added dropwise to the reaction vessel over a period of 4 hours. The mixture was kept at this temperature for 2 hours. After cooling, liquid alkali was slowly added to adjust the pH to 6 and water was added to obtain an esterified monomer with a solid content of 60%.

[0062] 2) Preparation of water-reducing agent: 260 parts of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 4000, 50 parts of the above-mentioned esterified monomer with a solid content of 60% and 300 parts of water are stirred and dissolved at 15°C for 1 h to obtain the first mixture. Add 2 parts of 1% ferrous sulfate aqueous solution, 2 parts of potassium persulfate, 6 parts of hydrogen peroxide and 2 parts of N,N-vinylbisacrylamide to the first mixture in sequence, and stir for 5 min to obtain the second mixture. 2.4 parts of 3-mercaptopropionic acid, 2 parts of vitamin C, and 60 parts of water were stirred to obtain a third mixture; The fourth mixture was prepared by mixing 40 parts acrylic acid, 50 parts esterification monomer, 10 parts acrylamide and 50 parts water. The third and fourth mixtures were added dropwise to the second mixture at 60 min and 50 min times, respectively. After maturation for 2 h, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0063] Comparative Example 1 Comparative Example 1 of this application provides a commercially available BASF BS-1 water-retaining polycarboxylate superplasticizer with a solid content of 50%.

[0064] Comparative Example 2 Comparative Example 2 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: Preparation of esterified monomer: 530 parts of methoxy polyethylene glycol with a molecular weight of 1200 were melted and added to a reaction vessel along with 4 parts of concentrated sulfuric acid and 4 parts of hydroquinone. Nitrogen gas was introduced for protection. After heating to 100°C, 64 parts of acrylic acid were added dropwise to the reaction vessel over a period of 4 hours. The mixture was kept at this temperature for 2 hours. After cooling, liquid alkali was slowly added to adjust the pH to 6 and water was added to obtain an esterified monomer with a solid content of 60%.

[0065] Preparation of water-reducing agent: 360 parts of esterified monomer and 320 parts of water were stirred and dissolved at 15°C for 1 h to obtain the first mixture; Add 1 part of crosslinking agent, 3 parts of 1% ferrous sulfate aqueous solution and 4 parts of hydrogen peroxide to the first mixture in sequence, and stir for 5 min to obtain the second mixture; The third mixture was prepared by stirring 2 parts mercaptoethanol, 0.5 parts vitamin C, and 60 parts water. Mix 40 parts acrylic acid, 5 parts acrylamide and 40 parts water to obtain a fourth mixture; The third and fourth mixtures were added dropwise to the second mixture at 60 min and 50 min times, respectively. After maturation for 1 hour, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0066] Comparative Example 3 Comparative Example 3 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: 360 parts of 4-hydroxybutylvinyl polyoxyethylene ether with a molecular weight of 3000 and 320 parts of water were stirred and dissolved at 15°C for 1 hour to obtain the first mixture. Add 1 part of crosslinking agent, 3 parts of 1% ferrous sulfate aqueous solution and 4 parts of hydrogen peroxide to the first mixture in sequence, and stir for 5 min to obtain the second mixture; The third mixture was prepared by stirring 2 parts mercaptoethanol, 0.5 parts vitamin C, and 60 parts water. Mix 40 parts acrylic acid, 5 parts acrylamide and 40 parts water to obtain a fourth mixture; The third and fourth mixtures were added dropwise to the second mixture at 60 min and 50 min times, respectively. After maturation for 1 hour, the pH was adjusted to 5 and water was added to obtain a polycarboxylate superplasticizer with a solid content of 40%.

[0067] Comparative Example 4 Comparative Example 4 of this application provides a method for preparing a polycarboxylate superplasticizer, comprising the following steps: Esterification reaction: 200.0g of methoxy polyethylene glycol with a molecular weight of 4000, 52.2g of methyl acrylate, and 80.0g of CH3(CH2)11C6H4(OC2H4) were added. 20 OH and 1.25g of polymerization inhibitor (phenthiazine hydroquinone) were mixed and heated to 40-60°C under nitrogen protection. Then, 3.15g of catalyst 4-dimethylaminopyridine was added, and the temperature was raised to 80-90°C. The reaction was carried out at a constant temperature for 8 hours. After the reaction was completed, the temperature was lowered to room temperature to obtain a first mixture containing esterification products and unreacted unsaturated acids and unsaturated carboxylic acid esters.

[0068] Copolymerization reaction: Take 100.0g of the first mixture obtained in step (1), 200.0g of isopentenyl alcohol polyoxyethylene ether with a molecular weight of 5000, 16.0g of methacrylic acid, 30.0g of compound A (R1 is -CH2, R2 is CH3, n is 100) and 200.0g of deionized water and add them to the reaction vessel and mix. Add hydrogen peroxide aqueous solution (3.00g of hydrogen peroxide and 30.00g of water), sodium formaldehyde sulfoxylate aqueous solution (2.0g of sodium formaldehyde sulfoxylate and 30.00g of water), and mercaptopropionic acid aqueous solution (1.83g of mercaptopropionic acid and 30.00g of water) dropwise into the reaction vessel to carry out the reaction. The reaction temperature is room temperature, the dropwise addition time is 4h, and the temperature is kept warm for 3h after the dropwise addition is completed.

[0069] The copolymer obtained in step (2) is adjusted to pH 5-7 with alkali, and water is added to adjust the polymer mass concentration to 45%-55% to obtain the ether ester copolymer polycarboxylic acid water-reducing agent; the structural formula of compound A is shown in formula (I): (I).

[0070] Performance testing The performance of the copolymer polycarboxylate superplasticizers of Examples 1 to 8 and the polycarboxylate superplasticizers of Comparative Examples 1 to 4 was determined. Specifically, the polycarboxylate superplasticizers of Examples 1 to 8 and Comparative Examples 1 to 4 were tested in cement paste and concrete according to the national standards “GB 8076-2008 Concrete Admixtures”, “GB 8077-2012 Test Method for Homogeneity of Concrete Admixtures”, and “GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures”. The results of the cement paste test are shown in Table 1, and the results of the concrete test are shown in Table 2.

[0071] The cement selected were Washi Cement, Gezhouba Cement, and Huaxin Cement, all with P·O 52.5, and the water-reducing agent addition was 0.15%.

[0072] Table 1. Flowability test results of polycarboxylate superplasticizer cement paste in Examples 1 to 8 and Comparative Examples 1 to 4

[0073] The concrete formula consists of 352 kg of cement (P·O 52.5), 118 kg of fly ash (Grade I), 682 kg of river sand, 334 kg of small stones (5-10 mm), 779 kg of crushed stone (10-20 mm), and 150 kg of water. The amount of water-reducing agent and water added to the blank group should be such that the initial spread of the concrete is (550±10) mm.

[0074] Table 2. Concrete performance test results of polycarboxylate superplasticizers in Examples 1 to 8 and Comparative Examples 1 to 4

[0075] As shown in Tables 1 and 2, the polycarboxylate superplasticizers in Examples 1 to 8 have moderate water reduction rates, good slump retention, low sensitivity to cement, good concrete workability, rich slurry, good encapsulation, and no obvious bleeding phenomenon was found during the process. After forming the barrel mold, there were basically no sand lines or watermarks, and the water retention effect was significantly better.

[0076] Comparative Example 1's main function is water retention, with a low water reduction rate, poor slump retention performance, and average concrete workability.

[0077] Comparative Example 2 is a polycarboxylate superplasticizer synthesized from pure ester monomers. It has a shorter molecular side chain, a lower water reduction rate, but a poorer water retention effect.

[0078] Comparative Example 3 is a polycarboxylate superplasticizer synthesized from pure ether monomers. It is highly sensitive to cement, has poor slump retention, and suffers from severe bleeding, essentially lacking any water retention effect.

[0079] Comparative Example 4, without the use of a crosslinking agent, is a chain-like compound formed by copolymerizing unsaturated polyethers and low-molecular-weight esterified monomers as side chains with unsaturated acids, monomers containing benzene rings, and imide structures. Esterification is achieved through transesterification. Simple modifications, such as introducing rigid structures like benzene rings, enhance adsorption and electrostatic repulsion, breaking down the cement flocculation structure and releasing free water to reduce viscosity. However, its drawback is its easily coiled linear chain structure, resulting in poor spreadability and coverage on the cement particle surface. Unlike network structures, it cannot effectively lock in water through molecular chain entanglement or form a thick and dense adsorbed water film, leading to low water retention. Furthermore, the transesterification reaction is difficult to control precisely, easily causing uneven distribution of side chains, making it relatively sensitive to cement and leading to localized osmotic pressure imbalances and rapid water loss.

[0080] In summary, compared to polyether monomers, the hydrophobic interactions and physical entanglement between the long chains of esterified monomers can form a dynamic network similar to a gel in aqueous solution. Water molecules are filled and "locked" in the network gaps. After absorbing water, the polymer chains stretch, and the network expands to form a gel-like structure, further hindering the free diffusion of water. Therefore, the mother liquor synthesized from esterified monomers has lower sensitivity to cement and other adhesives, and its ester groups have a slow-release effect, thus providing slump retention. In addition, the molecular structure of the synthesized water-reducing agent mother liquor forms a network structure under the action of the crosslinking agent, increasing steric hindrance. While improving the water reduction rate of the water-reducing agent, it can limit the exudation of water molecules. The copolymerized polycarboxylate water-reducing agent not only has low sensitivity and slump retention, but also has a strong water retention effect. This is because the synthesized polycarboxylate water-reducing agent mother liquor, under the action of the crosslinking agent, connects multiple originally linear water-reducing agent molecular chains to form a micro-crosslinked three-dimensional network structure. This structure alters its adsorption behavior on the surface of cement particles, effectively increasing the viscosity of the solution within the capillary pores of the cement paste. It also adsorbs some free water through its network space, thus delaying water evaporation and exudation, thereby playing a water-retaining role. Furthermore, after dissolving in water, it forms a thin, viscous, gel-like film structure. Water molecules entering this film structure are strongly constrained, and the interaction forces between water molecules are strengthened, restricting the diffusion and flow of free water.

[0081] Copolymer polycarboxylate superplasticizers contain a large number of hydrophilic groups such as carboxyl and amide groups. After the carboxyl and amide groups dissociate, they combine with water molecules in large quantities through hydrogen bonding to form a dense "hydration film" with a colloidal network structure, thereby locking in water. On the other hand, the carboxyl and amide groups attract cations, and the cation concentration in the network is higher than that in the water, resulting in an ion concentration difference and osmotic pressure between the internal and external solutions, which drives water molecules to diffuse into the polymer and be fixed.

[0082] The crosslinking agent contains divinyl groups, which, under the action of free radical initiators, allow the two highly polymerizable vinyl groups to open simultaneously and covalently bond with the two main polymer chains in the system, thereby introducing a micro-crosslinking structure and transforming the traditional comb-like water-reducing agent molecules into a three-dimensional network structure. Furthermore, the flexible segments in the middle impart a certain degree of flexibility to the network structure, effectively maintaining its integrity.

[0083] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0084] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0085] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A copolymeric polycarboxylate superplasticizer, characterized in that, Its raw material composition includes: esterified monomers, unsaturated polyether monomers, unsaturated carboxylic acids, unsaturated amide monomers, crosslinking agents, chain transfer agents, oxidizing agents, and reducing agents, wherein: The esterified monomer is polymerized from unsaturated carboxylic acids and polyol monomers; The esterified monomer and the polyether monomer are cross-linked and copolymerized by a cross-linking agent to form a three-dimensional network structure of the ether ester copolymer polycarboxylate superplasticizer; The crosslinking agent includes compounds containing divinyl groups.

2. The copolymeric polycarboxylate superplasticizer as described in claim 1, characterized in that: The unsaturated polyether monomer has a molecular weight of 2400~4000; and / or, The molecular weight of the polyol monomer is 300~1200; and / or, The mass ratio of the esterified monomer to the unsaturated polyether monomer is (0.1~1):

1.

3. The copolymeric polycarboxylate superplasticizer as described in claim 1, characterized in that, When synthesizing esterified monomers, the molar ratio of unsaturated carboxylic acids to polyol monomers is (1.5~5):

1.

4. The copolymeric polycarboxylate superplasticizer as described in claim 1, characterized in that: The polyol monomers include at least one of polyethylene glycol and methoxylated polyethylene glycol; and / or, The unsaturated carboxylic acid includes at least one of acrylic acid, methacrylic acid, and maleic acid; and / or, The unsaturated polyether monomer includes at least one selected from methyl allyl polyethylene glycol ether, methyl allyl polyethylene glycol ether, ethylene glycol monovinyl polyethylene glycol ether, and 4-hydroxybutyl vinyl polyoxyethylene ether; and / or The unsaturated amide monomer includes at least one of acrylamide, N,N-dimethylacrylamide, and isopropylacrylamide; and / or, The crosslinking agent includes at least one of N,N-methylenebisacrylamide, N,N-vinylbisacrylamide, and ethylene glycol dimethacrylate; and / or The chain transfer agent comprises at least one selected from sodium hypophosphite, 3-mercaptopropionic acid, mercaptoacetic acid, and mercaptoethanol; and / or, The oxidant includes at least one selected from hydrogen peroxide, ammonium persulfate, and potassium persulfate; and / or, The reducing agent includes at least one of vitamin C, sodium formaldehyde sulfoxylate, sodium dioctyl succinate, sodium sulfite, and ferrous sulfate heptahydrate.

5. The copolymeric polycarboxylate superplasticizer as described in claim 1, characterized in that, By mass, its raw materials include: 200-360 parts of unsaturated polyether monomer, 20-200 parts of esterified monomer, 10-40 parts of unsaturated carboxylic acid, 5-10 parts of unsaturated amide monomer, 1-3 parts of crosslinking agent, 1-5 parts of chain transfer agent, 2-10 parts of oxidizing agent, and 0.5-2 parts of reducing agent.

6. A method for preparing a copolymeric polycarboxylate superplasticizer as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Unsaturated carboxylic acids and polyol monomers are esterified to obtain esterified monomers; The unsaturated polyether monomer is mixed with the first esterified monomer to obtain the first mixture; The first mixture is mixed with a chain transfer agent, a reducing agent, an oxidizing agent, a crosslinking agent, an unsaturated carboxylic acid, an unsaturated amide monomer, and a second part of the esterification monomer, and then matured to obtain a polycarboxylic acid water-reducing agent.

7. The preparation method of the copolymeric polycarboxylate superplasticizer as described in claim 6, characterized in that: The esterification temperature is 95℃~125℃; and / or, The esterification time is 5h~8h.

8. The preparation method of the copolymeric polycarboxylate superplasticizer as described in claim 6, characterized in that, The process of mixing the unsaturated polyether monomer with the first portion of the esterified monomer to obtain the first mixture is as follows: The mixing temperature is 8℃~25℃; and / or, The mixing time is 0.5h to 3h.

9. The preparation method of the copolymeric polycarboxylate superplasticizer as described in claim 6, characterized in that, The process involves mixing the first mixture with a chain transfer agent, a reducing agent, an oxidizing agent, a crosslinking agent, an unsaturated carboxylic acid, an unsaturated amide monomer, and a second portion of the esterification monomer, followed by aging, to obtain the polycarboxylic acid water-reducing agent. The maturation time is 1 to 3 hours.

10. A type of concrete, characterized in that, Includes the copolymeric polycarboxylate superplasticizer as described in any one of claims 1 to 5, or the copolymeric polycarboxylate superplasticizer prepared by the preparation method of the copolymeric polycarboxylate superplasticizer as described in any one of claims 6 to 9.

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