A fast-dispersing, viscosity-reducing polycarboxylate superplasticizer, its preparation method and application

Abstract

This invention provides a fast-dispersible, viscosity-reducing polycarboxylate superplasticizer, its preparation method, and its application. The fast-dispersible, viscosity-reducing polycarboxylate superplasticizer of this invention is obtained through a copolymerization reaction of polyether macromonomers, unsaturated ester monomers, unsaturated acid monomers, and styrene. These monomers are distributed in a stepped manner along the superplasticizer molecular chain, with the polyether macromonomers and unsaturated ester monomers concentrated on one side of the superplasticizer molecular chain, and the unsaturated acid monomers and styrene monomers concentrated on the other side. The superplasticizer of this invention has the advantages of significant water reduction and long slump retention in high-strength concrete, and also has a viscosity-reducing effect; it can quickly bring fresh concrete to its maximum spreadability, saving mixing time for production enterprises and improving production efficiency. Furthermore, it can suppress the phenomenon of increased concrete fluidity due to low temperatures. The superplasticizer of this invention is produced using a one-pot process, which is simple and suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to a fast-dispersing, viscosity-reducing polycarboxylate superplasticizer, its preparation method, and its application, belonging to the technical field of concrete admixtures. Background Technology

[0002] Water-reducing agents (also known as "cement dispersants") are currently the most widely researched and applied admixtures for concrete. While maintaining the workability of concrete, adding water-reducing agents can effectively save cement usage, reduce water consumption, and improve the workability and strength of concrete. Polycarboxylate superplasticizers are considered the third generation of water-reducing agents, with a water reduction rate of approximately 25% to 40%. Due to their advantages such as low dosage, high water reduction rate, good slump retention, highly adjustable molecular structure, and environmental friendliness, polycarboxylate superplasticizers have become the mainstream water-reducing agent product, with their market share increasing year by year, currently exceeding 70%.

[0003] The superior performance of polycarboxylate superplasticizers stems from their unique molecular structure. Essentially, polycarboxylate is a water-soluble comb-shaped polymer composed of a main chain rich in carboxylic acid groups and polyoxyalkylene ether (polyether) side chains. The carboxylic acid groups on the polycarboxylate main chain can be directionally adsorbed onto the surface of positively charged cement or cement hydrates, while the polyether side chains extend in solution to form a hydration layer, providing steric repulsion to prevent cement agglomeration. Therefore, it imparts excellent fluidity to cement paste.

[0004] A current research focus in the field of polycarboxylate superplasticizers is the design of novel polycarboxylate molecular structures and their impact on macroscopic properties. Numerous patents have reported synthetic methods for various polycarboxylate compounds with novel structures, with the innovations primarily focusing on the design of novel topologies and raw material monomers.

[0005] Patent CN102911322 B discloses a method for synthesizing a star-shaped polycarboxylate superplasticizer. A star-shaped polymerizable active molecule is prepared through an esterification reaction between a polyol and acrylic acid, and then copolymerized with conventional polycarboxylate raw material monomers to obtain the star-shaped polycarboxylate superplasticizer. This product exhibits superior cement paste fluidity and slump retention compared to conventional comb-shaped polycarboxylate superplasticizers, as well as good cement applicability and concrete application performance. Patent CN102093520 B discloses a method for preparing a hyperbranched polycarboxylate superplasticizer. An active monomer with both polymeric and chain transfer groups is prepared through an esterification reaction between a polyether side chain and a thiol chain transfer agent. This monomer is then copolymerized with an unsaturated acid monomer to obtain a hyperbranched polycarboxylate superplasticizer. The product exhibits excellent cement dispersion ability and good slump retention. Patent CN102153711 B discloses a method for preparing a retarded polycarboxylate superplasticizer. Its innovation lies in introducing β-cyclodextrin side chains with retarding function into the polycarboxylate molecular backbone. The prepared superplasticizer exhibits retarding properties, micro-air-entraining properties, and better dispersibility. Patent CN104031216 B discloses a polyether-amide type polycarboxylate superplasticizer. Polyetheramine monomers are prepared by reacting polyetheramine with acyl chloride monomers, and then copolymerizing these monomers with unsaturated acids and polyether monomers to obtain the product. This product has advantages such as high water reduction rate and good workability in concrete applications. Patent CN103011680 B discloses a sulfate-resistant polycarboxylate superplasticizer, mainly prepared from polyether monomers, carboxylic acid monomers, organosilicon monomers, and sulfonic acid monomers using a free radical copolymerization method. The silane bonds in the product molecule can form strong chemical bonds with silicates in cement to resist the competitive adsorption of sulfate ions, thereby improving the poor compatibility between polycarboxylate superplasticizers and high-sulfate concrete materials.

[0006] High-strength concrete (C60-C100) is widely used in large-scale landmark projects due to its superior mechanical properties and excellent durability. However, due to the low water content (water-cement ratio of about 0.3), conventional polycarboxylate superplasticizers cannot meet the performance requirements of high-strength concrete. The three most prominent issues are: (1) The water reduction rate of existing polycarboxylate superplasticizers is insufficient, resulting in insufficient fluidity of high-strength concrete and construction difficulties; (2) High-strength concrete will inevitably require the addition of more superplasticizers, and the superplasticizer molecules need a certain amount of time to disperse in the concrete. Therefore, high-strength concrete requires manufacturers to mix for a longer time, resulting in low production efficiency; (3) High-strength concrete has a high viscosity, making pumping difficult.

[0007] In conclusion, developing a novel polycarboxylate superplasticizer with excellent water reduction rate, fast dispersion speed, and viscosity improvement effect is of great significance for the large-scale promotion of high-strength concrete and for advancing the development of modern admixture technology. Summary of the Invention

[0008] To address the shortcomings of existing technologies, and based on the theory that upstream structure influences downstream performance, this invention optimizes the polycarboxylate sequence structure to prepare a novel polycarboxylate water-reducing agent suitable for high-strength concrete construction. Conventional polycarboxylates are random copolymers in terms of molecular sequence structure, and this molecular sequence structure significantly affects the dispersion properties, adsorption conformation, adsorption free energy, and surface zeta potential of polycarboxylate on cement particle surfaces. For example, some researchers have reported the synthesis methods and properties of block polycarboxylates (Ran Q, Wang X, Jiang J, et al. Synthesis of block polycarboxylate copolymer and its application in a cement system[J]. Advances in Cement Research, 2016, 28(3):202-208.). This invention synthesizes a novel gradient polymer as a water-reducing agent using atom transfer radical polymerization. This water-reducing agent, when applied to high-strength concrete, exhibits significant water reduction, long slump retention time, rapid dispersion in cement paste, saving mixing time, and reducing concrete viscosity, showing broad market application prospects.

[0009] This invention provides a fast-dispersible, viscosity-reducing polycarboxylate superplasticizer, wherein the polycarboxylate superplasticizer is a gradient polymer, and its molecular structure is shown in formula (I):

[0010]

[0011] In formula (Ⅰ), R1 is -H or -CH3;

[0012] R2 is -CO-, -CH2, -CH2CH2-, -OCH2CH2-, or -OCH2CH2CH2CH2-;

[0013] R3 is either -H or -CH3;

[0014] R4 is -NH2, -NHCH2OH, -OCH2CH2OH, -OCH2CH2CH2OH or -OR7, where R7 is a C1 to C4 alkyl group;

[0015] R5 is -H, -CH3, or -CH2COO - ;

[0016] R6 is either -H or -COO - ;

[0017] a, b, c, d, and n represent the number of repeating units in each repeating unit and are all integers, where a = 2 to 50, b = 5 to 140, c = 25 to 100, d = 5 to 20, and n = 22 to 90.

[0018] The adsorption groups and side chains in the gradient polymer are distributed in a stepwise manner on a main chain, which makes its adsorption and steric hindrance effects significantly different from those of ordinary random copolymerized polycarboxylic acid, thereby improving its performance as a water-reducing agent, such as water reduction rate, dispersion speed, and viscosity improvement effect.

[0019] Through extensive experiments, the researchers of this invention discovered that, compared to conventional random copolymer polycarboxylate molecules, gradient polycarboxylate exhibits a gradient distribution of its anionic adsorption groups and polyether side chains along the main chain. This results in a relatively concentrated adsorption group or side chain in localized areas, significantly enhancing adsorption capacity and reducing steric hindrance of the side chains. Consequently, it significantly improves the dispersion effect of gradient polycarboxylate on cement particles. The structural comparison between random copolymer polycarboxylate and gradient polycarboxylate is shown below. In random copolymer polycarboxylate, the side chains and adsorption groups are uniformly distributed along the main chain. However, in gradient polycarboxylate, for example, the side chains are distributed in three gradients: a high-density distribution in one segment, a sparse distribution in another, and an even sparser distribution in the last segment. Similarly, the adsorption groups are distributed in a high-density distribution in one segment, a sparse distribution in another, and no or even sparse distribution in the last segment.

[0020]

[0021] The fast-dispersible, viscosity-reducing polycarboxylate superplasticizer of the present invention is obtained by copolymerization of polyether macromonomers, unsaturated ester monomers, unsaturated acid monomers, and styrene. These monomers are distributed in a stepwise manner on the molecular chain of the superplasticizer.

[0022] The polyether macromonomer and unsaturated ester monomer are concentrated on one side of the water-reducing agent molecular chain. The polyether macromonomer acts as a side chain and plays a steric role, while the unsaturated ester monomer makes up for the problem that the polyether macromonomer cannot self-polymerize into chains. At the same time, it can release carboxylic acid groups after being added to cement paste, thereby enhancing the slump retention ability of the water-reducing agent molecules.

[0023] The unsaturated acid monomer and styrene monomer are concentrated on the other side of the water-reducing agent molecular chain. The unsaturated acid monomer contains carboxylic acid groups, which play a role in adsorbing cement particles. The copolymerization of styrene with it can improve the rigidity of the carboxylic acid chain segments, so that the excessive carboxylic acid groups will not be buried due to the excessive entanglement of the chain segments themselves.

[0024] The fast-dispersible, viscosity-reducing polycarboxylate superplasticizer described in this invention is prepared by atom transfer radical polymerization, a mature synthesis technique. Reference can be found in: Matyjaszewski K, Xia J. Atom transfer radical polymerization[J]. Chemical reviews, 2001, 101(9):2921-2990.

[0025] This invention provides a method for preparing the fast-dispersible, viscosity-reducing polycarboxylate superplasticizer, the specific steps of which are as follows:

[0026] (1) Synthesis of prepolymer PC-1: Initiator, catalyst, ligand and monomer A-1 are thoroughly mixed, O2 in the system is removed by N2, the temperature is raised to 80-140℃, and then monomer B-1 is slowly added dropwise. The reaction is carried out for 1-5 hours to obtain PC-1.

[0027] The molar ratio of the initiator, catalyst, ligand, monomer A-1, and monomer B-1 is 1:1:1~2:2~40:3~100;

[0028] (2) Synthesis of prepolymer PC-2: Add monomer A-2 and monomer B-2 to PC-1 obtained in step (1), heat to 100-150℃, and polymerize for 1-5 hours to obtain PC-2.

[0029] The molar ratio of monomer A-2, monomer B-2 and catalyst in step (1) is 0-10:2-40:1;

[0030] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add monomer C and monomer D to PC-2 obtained in step (2), heat to 100-150℃, polymerize for 1-5 hours, and then filter to remove catalyst and ligand to obtain the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention.

[0031] The molar ratio of monomer C, monomer D and catalyst in step (1) is 25-100:5-20:1;

[0032] The monomers A-1 and A-2 mentioned in steps (1) and (2) are polyether macromonomers, and monomers with the following molecular structural formula (II) can be selected independently:

[0033]

[0034] In formula (II), n is an integer from 22 to 90, representing the number of repeating units of the repeating unit; R1 is -H or -CH3, and R2 is -CO-, -CH2, -CH2CH2-, -OCH2CH2- or -OCH2CH2CH2CH2-.

[0035] The monomers A-1 and A-2 mentioned in steps (1) and (2) have a weight-average molecular weight of 1000 to 4000. They are both common polyether macromonomers used in the synthesis of polycarboxylate superplasticizers and are both commercial industrial products. The monomers A-1 and A-2 can be the same or different.

[0036] The monomers B-1 and B-2 mentioned in steps (1) and (2) are unsaturated esters, and monomers with the following molecular structures can be selected independently:

[0037]

[0038] In formula (Ⅲ), R3 is -H or -CH3; R4 is -NH2, -NHCH2OH, -OCH2CH2OH, -OCH2CH2CH2OH or -OR7, and R7 is a C1 to C4 alkyl group;

[0039] The monomers B-1 and B-2 mentioned in steps (1) and (2) can be the same or different;

[0040] In step (3), monomer C is an unsaturated acid monomer selected from any one or more of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid or maleic anhydride;

[0041] The monomer D mentioned in step (3) is styrene.

[0042] The initiator described in step (1) has the following molecular structural formula:

[0043]

[0044] In the formula, m = 0 or 1; when m = 0, R8 is C6H5-, CH2=CH-, CH2=CHCH2-, HOCH2CH2CH2-, When m = 1, R8 is CH3CH2-, HOCH2CH2-, CH2=CHCH2-, C6H5-, or CH2=CH-; R9 is -H or -CH3; R 10 It is -H or -CH3; X is a chlorine atom or a bromine atom.

[0045] The catalyst mentioned in step (1) is cuprous chloride or cuprous bromide;

[0046] The ligand mentioned in step (1) is selected from any one of 2,2'-bipyridine (bpy), 4,4'-dinonyl-2,2'-bipyridine (dNbpy), N,N,N',N”,N”-pentamethyldiethylenetriamine (PMDETA), tris[2-(dimethylamino)ethyl]amine (Me6TREN), and N,N,N',N'-tetra(2-pyridylmethyl)ethylenediamine (TPEN).

[0047] In step (1), the weight-average molecular weight of prepolymer PC-1 is 10,000 to 60,000;

[0048] In step (2), the weight-average molecular weight of prepolymer PC-2 is 15,000 to 70,000.

[0049] After step (3) is completed, the weight average molecular weight of the fast-dispersible, viscosity-reducing polycarboxylate superplasticizer is 20,000 to 80,000.

[0050] In another aspect of the invention, the application of the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer as a cement dispersant is also provided.

[0051] The application method of the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer described in this invention is the same as that of known cement dispersants, and its application method is generally known to those skilled in the art.

[0052] The fast-dispersing, viscosity-reducing polycarboxylate superplasticizer of this invention is added at a dosage of 0.05% to 0.3% of the total cementitious material mass. This dosage refers to the pure solid content, and the percentage is a mass percentage. Too low a dosage will degrade its performance, while too high a dosage will result in economic waste without improving performance.

[0053] The fast-dispersible, viscosity-reducing polycarboxylate superplasticizer described in this invention can be mixed with other commercially available superplasticizers, such as lignosulfonate superplasticizers, naphthalene sulfonate superplasticizers, and polycarboxylate superplasticizers. It can also be used after adding air-entraining agents, retarders, early-strength agents, expanding agents, thickeners, shrinkage reducers, and defoamers.

[0054] The fast-dispersing, viscosity-reducing polycarboxylate superplasticizer of the present invention has the following advantages compared with the prior art:

[0055] (1) In high-strength concrete, it has the advantages of large water reduction and long slump retention. When applied to the production of commercial concrete, it can save admixture and reduce enterprise costs.

[0056] (2) It can quickly bring fresh concrete to its maximum spread, save production time and improve production efficiency. In addition, it can also suppress the phenomenon of concrete fluidity increasing due to low temperature.

[0057] (3) It has the effect of reducing the viscosity of high-strength concrete, which can reduce the pumping difficulty during construction.

[0058] (4) The one-pot production method is simple and suitable for large-scale industrial production. Detailed Implementation

[0059] The technical solution of the present invention will be further described in detail below with reference to the embodiments. However, the present invention is by no means limited thereto. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the protection scope of the present invention.

[0060] In this embodiment of the invention, the molecular weight of the polymer was determined using a miniDAWN Tristar aqueous gel permeation chromatograph (GPC, Wyatt Technologies) equipped with a TSK-GELSW (Tosoh Biotechnology Co., Ltd.) column. The mobile phase was DMF, the flow rate was 1.0 mL / min, and the sample mass percentage concentration was 0.50%.

[0061] In the embodiments of this invention, polyether monomers A-1 and A-2 were purchased from Nanjing Bote New Materials Co., Ltd., and other raw materials were commercially available ordinary chemically pure reagents purchased from Innocare Chemical Reagent Co., Ltd.

[0062] The molecular structures and designations of the initiators used in the examples are shown below.

[0063]

[0064] Example 1

[0065] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-1 (0.03mol, 4.47g), catalyst cuprous chloride (0.03mol, 2.97g), ligand bpy (0.03mol, 4.68g), and monomer allyl polyoxyethylene ether (R1 is -H, R2 is -CH2; molecular weight 1000, 0.3mol, 300g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 100℃. Then, under N2 protection, monomer acrylamide (0.45mol, 31.95g) was slowly added. The reaction was carried out dropwise for 1h to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 10700.

[0066] (2) Synthesis of prepolymer PC-2: Add monomer methyl allyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2, molecular weight 2400, 0.15mol, 360g) and monomer acrylamide (0.24mol, 17.04g) to PC-1 obtained in step (1), heat to 120℃, and polymerize for 3h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 21700.

[0067] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add monomer acrylic acid (0.75mol, 54g) and monomer styrene (0.3mol, 31.2g) to PC-2 obtained in step (2), heat to 130℃, and polymerize for 3h. After filtering to remove catalyst and ligand, the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 25500.

[0068] Example 2

[0069] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-2 (0.02mol, 1.83g), catalyst cuprous chloride (0.02mol, 1.98g), ligand bpy (0.02mol, 3.12g), and monomer methacrylate polyoxyethylene ether (R1 is -CH3, R2 is -CO-, molecular weight 1000, 0.6mol, 600g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 80℃. Then, under N2 protection, monomer methyl acrylate (20mol, 172g) was slowly added dropwise. The reaction was carried out for 5h to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 35300.

[0070] (2) Synthesis of prepolymer PC-2: Add monomer methyl allyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2, molecular weight 2400, 0.1mol, 240g) and monomer hydroxyethyl acrylate (0.16mol, 18.24g) to PC-1 obtained in step (1), heat to 100℃, and polymerize for 5h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 49900.

[0071] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add monomer acrylic acid (0.5 mol, 72 g) and monomer styrene (2 mol, 20.8 g) to PC-2 obtained in step (2), heat to 150°C, and polymerize for 1 h. After filtering to remove the catalyst and ligand, the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 53800.

[0072] Example 3

[0073] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-3 (0.015mol, 2.03g), catalyst cuprous chloride (0.015mol, 1.485g), ligand bpy (0.015mol, 2.34g), and monomer polyoxyethylene methacrylate (R1 is -CH3, R2 is -CO-, molecular weight 1000, 0.6mol, 600g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 130℃. Then, under N2 protection, monomer tert-butyl methacrylate (1.2mol, 170.4g) was slowly added dropwise. The reaction was carried out for 3h to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 48300.

[0074] (2) Synthesis of prepolymer PC-2: Add monomers diethylene glycol monovinyl polyoxyethylene ether (R1 is -H, R2 is -OCH2CH2-, molecular weight 2400, 0.06mol, 144g) and hydroxyethyl acrylate (0.15mol, 17.1g) to PC-1 obtained in step (1), heat to 140℃, and polymerize for 5h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 60400.

[0075] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add monomer acrylic acid (1.5 mol, 108 g) and monomer styrene (0.375 mol, 39 g) to PC-2 obtained in step (2), heat to 135°C, and polymerize for 4 h. After filtering to remove the catalyst and ligand, the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 70,500.

[0076] Example 4

[0077] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-4 (0.02mol, 3.06g), catalyst cuprous chloride (0.02mol, 1.98g), ligand bpy (0.02mol, 3.12g), and monomer methyl allyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2, molecular weight 1600, 0.3mol, 480g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 100℃. Then, under N2 protection, monomer hydroxyethyl acrylate (1mol, 116g) was slowly added dropwise. After 5h of reaction, PC-1 was obtained. After the reaction was completed, the weight average molecular weight of the product was measured to be 27900.

[0078] (2) Synthesis of prepolymer PC-2: Add monomer hydroxyethyl acrylate (0.04 mol, 4.56 g) to PC-1 obtained in step (1), heat to 100℃, and polymerize for 1 h to obtain PC-2. After the reaction is completed, take a sample and measure the weight average molecular weight of the product to be 30100.

[0079] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add monomer acrylic acid (0.7mol, 50.4g) and monomer styrene (0.1mol, 10.4g) to PC-2 obtained in step (2), heat to 150℃, and polymerize for 2h. After filtering to remove catalyst and ligand, the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 33300.

[0080] Example 5

[0081] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-5 (0.01mol, 1.21g), catalyst cuprous chloride (0.01mol, 0.99g), ligand dNbpy (0.01mol, 4.09g), and monomer isopentenyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2CH2-, molecular weight 2400, 0.15mol, 360g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 130℃. Then, under N2 protection, monomer hydroxypropyl acrylate (0.5mol, 65g) was slowly added dropwise. The reaction was carried out for 4 hours to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 40600.

[0082] (2) Synthesis of prepolymer PC-2: Add isopentenyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2CH2-, molecular weight 1000, 0.04mol, 40g) and hydroxypropyl acrylate (0.4mol, 52g) to PC-1 obtained in step (1), heat to 140℃, and polymerize for 1h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 48800.

[0083] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add monomer acrylic acid (0.5 mol, 36 g) and monomer styrene (0.15 mol, 15.6 g) to PC-2 obtained in step (2), heat to 140°C, and polymerize for 2 h. After filtering to remove the catalyst and ligand, the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 54,100.

[0084] Example 6

[0085] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-6 (0.01mol, 1.51g), catalyst cuprous chloride (0.01mol, 0.99g), ligand PMDETA (0.12mol, 2.08g), and monomer isopentenyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2CH2-, molecular weight 2400, 0.15mol, 360g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 130℃. Then, under N2 protection, monomer hydroxyethyl acrylate (0.2mol, 23.2g) was slowly added dropwise. The reaction was carried out for 2 hours to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 35900.

[0086] (2) Synthesis of prepolymer PC-2: Add allyl polyoxyethylene ether (R1 is -H, R2 is -CH2, molecular weight 1000, 0.1mol, 100g) and hydroxypropyl acrylate (0.2mol, 26g) to PC-1 obtained in step (1), heat to 130℃, and polymerize for 2h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 49600.

[0087] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add monomer methacrylic acid (0.5 mol, 43 g) and monomer styrene (0.1 mol, 10.4 g) to PC-2 obtained in step (2), heat to 130°C, and polymerize for 4 h. After filtering to remove the catalyst and ligand, the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 55200.

[0088] Example 7

[0089] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-7 (0.01mol, 1.41g), catalyst bromide chloride (0.01mol, 1.44g), ligand PMDETA (0.12mol, 2.08g), and monomer isopentenyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2CH2-, molecular weight 2400, 0.2mol, 480g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 130℃. Then, under N2 protection, monomer hydroxyethyl acrylate (0.3mol, 34.8g) was slowly added dropwise. The reaction was carried out for 2 hours to obtain PC-1. After the reaction was completed, a sample was taken and the weight average molecular weight of the product was measured to be 51300.

[0090] (2) Synthesis of prepolymer PC-2: Add monomer acrylamide (0.05 mol, 3.55 g) to PC-1 obtained in step (1), heat to 130℃, and polymerize for 2 h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 53400.

[0091] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add monomer methacrylic acid (1 mol, 86 g) and monomer styrene (0.08 mol, 8.32 g) to PC-2 obtained in step (2), heat to 140°C, and polymerize for 4 h. After filtering to remove the catalyst and ligand, the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 62600.

[0092] Example 8

[0093] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-8 (0.01mol, 1.85g), catalyst cuprous bromide (0.01mol, 1.44g), ligand PMDETA (0.15mol, 2.6g), and monomer methyl allyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2, molecular weight 2400, 0.1mol, 240g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 130℃. Then, under N2 protection, monomer acrylamide (0.2mol, 14.2g) was slowly added dropwise. The reaction was carried out for 2 hours to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 24800.

[0094] (2) Synthesis of prepolymer PC-2: Add allyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2, molecular weight 2000, 0.08mol, 160g) and methyl methacrylate (0.15mol, 15g) to PC-1 obtained in step (1), heat to 130℃, and polymerize for 2h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 40200.

[0095] (3) Synthesis of fast-dispersible, viscosity-reducing polycarboxylate superplasticizer: Add monomer acrylic acid (0.4 mol, 28.8 g), monomer maleic anhydride (0.2 mol, 19.8 g), and monomer styrene (0.08 mol, 8.32 g) to PC-2 obtained in step (2), heat to 150°C, and polymerize for 5 h. After filtering to remove the catalyst and ligand, the fast-dispersible, viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 43900.

[0096] Example 9

[0097] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-2 (0.01mol, 0.92g), catalyst cuprous bromide (0.01mol, 1.44g), ligand PMDETA (0.15mol, 2.6g), and monomer methyl allyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2, molecular weight 2400, 0.1mol, 240g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 140℃. Then, under N2 protection, monomer methyl methacrylate (0.2mol, 20g) was slowly added dropwise. The reaction was carried out for 4 hours to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 25400.

[0098] (2) Synthesis of prepolymer PC-2: Add monomer methyl allyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2, molecular weight 1600, 0.08mol, 128g) and monomer methyl methacrylate (0.15mol, 15g) to PC-1 obtained in step (1), heat to 150℃, and polymerize for 1h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 39200.

[0099] (3) Synthesis of fast-dispersible, viscosity-reducing polycarboxylate superplasticizer: Add monomers methacrylic acid (0.1 mol, 8.6 g), itaconic acid (0.2 mol, 26 g), and styrene (0.08 mol, 8.32 g) to PC-2 obtained in step (2), heat to 150°C, and polymerize for 3 h. After filtering to remove the catalyst and ligand, the fast-dispersible, viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 42,500.

[0100] Example 10

[0101] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-3 (0.01mol, 1.35g), catalyst cuprous bromide (0.01mol, 1.44g), ligand PMDETA (0.02mol, 3.46g), and monomer diethylene glycol monovinyl polyoxyethylene ether (R1 is -H, R2 is -OCH2CH2-, molecular weight 3000, 0.1mol, 300g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 140℃. Then, under N2 protection, monomer acrylamide (0.2mol, 14.2g) was slowly added dropwise. The reaction was carried out for 4 hours to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 31500.

[0102] (2) Synthesis of prepolymer PC-2: Add isopentenyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2CH2-, molecular weight 2400, 0.04mol, 96g) and propyl acrylate (0.1mol, 11.4g) to PC-1 obtained in step (1), heat to 140℃, and polymerize for 3h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 42500.

[0103] (3) Synthesis of fast-dispersible, viscosity-reducing polycarboxylate superplasticizer: Add monomer acrylic acid (0.4 mol, 28.8 g), monomer maleic anhydride (0.1 mol, 9.8 g), and monomer styrene (0.08 mol, 8.32 g) to PC-2 obtained in step (2), heat to 150°C, and polymerize for 2 h. After filtering to remove the catalyst and ligand, the fast-dispersible, viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 44,100.

[0104] Example 11

[0105] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-4 (0.02mol, 3.06g), catalyst cuprous bromide (0.02mol, 2.87g), ligand ME6TREN (0.024mol, 5.52g), and monomer diethylene glycol monovinyl polyoxyethylene ether (R1 is -H, R2 is -CH2CH2-, molecular weight 3000, 0.1mol, 300g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 130℃. Then, under N2 protection, monomer acrylamide (0.1mol, 7.1g) and monomer ethyl acrylate (0.2mol, 10g) were slowly added dropwise. The reaction was carried out for 5h to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 14100.

[0106] (2) Synthesis of prepolymer PC-2: Add monomer hydroxyethyl acrylate (0.1 mol, 11.4 g) to PC-1 obtained in step (1), heat to 150℃, and polymerize for 5 h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 16800.

[0107] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add maleic anhydride (1 mol, 98 g) and styrene (0.2 mol, 20.8 g) monomers to PC-2 obtained in step (2), heat to 150°C, and polymerize for 5 h. After filtering to remove the catalyst and ligand, the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 22000.

[0108] Example 12

[0109] (1) Synthesis of prepolymer PC-1: In a four-necked flask equipped with a stirrer, thermometer, and N2 pipeline, initiator I-5 (0.02mol, 2.41g), catalyst cuprous bromide (0.02mol, 2.87g), ligand TPEN (0.02mol, 8.5g), and monomer 4-hydroxybutylvinyl polyoxyethylene ether (R1 is -H, R2 is -OCH2CH2CH2CH2-, molecular weight 4000, 0.06mol, 240g) were thoroughly mixed. N2 was passed through to remove O2 from the system, and the temperature was raised to 120℃. Then, under N2 protection, monomer acrylamide (0.05mol, 3.05g) and monomer ethyl acrylate (0.05mol, 5g) were slowly added dropwise. The reaction was carried out for 5h to obtain PC-1. After the reaction was completed, the weight average molecular weight of the product was measured to be 11400.

[0110] (2) Synthesis of prepolymer PC-2: Add monomer isopentenyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2CH2-, molecular weight 3600, 0.1mol, 360g) and hydroxyethyl acrylate (0.2mol, 22.8g) to PC-1 obtained in step (1), heat to 150℃, and polymerize for 4h to obtain PC-2. After the reaction is completed, the weight average molecular weight of the product is measured to be 30600.

[0111] (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add maleic acid (1 mol, 116 g) and styrene (0.2 mol, 20.8 g) monomers to PC-2 obtained in step (2), heat to 150°C, and polymerize for 5 h. After filtering to remove the catalyst and ligands, the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer of the present invention can be obtained. The weight average molecular weight of the product was measured to be 37,500.

[0112] Comparative Example 1:

[0113] Commercially available high-performance polycarboxylate superplasticizers, GPC measured M w The value is 33700, and the molecular weight distribution coefficient is 1.68.

[0114] Comparative Example 2:

[0115] Add methyl allyl polyoxyethylene ether (R1 is -CH3, R2 is -CH2, M...) to a flask equipped with a stirrer. wA mixture of 0.1 mol (240 g) of acrylic acid (2400 molecular weight), 1.0 g of 30% hydrogen peroxide, and 240 g of water was prepared and stirred until heated to 45°C. At this temperature, a mixed solution consisting of 0.4 mol (28.8 g) of acrylic acid, 0.0125 mol (1.33 g) of mercaptopropionic acid, 0.0025 mol (0.44 g) of L-ascorbic acid, and 30 g of water was added dropwise over 3 hours. After the addition was complete, the mixture was kept at this temperature for 1 hour. Finally, the pH of the reaction solution was neutralized to 7 with sodium hydroxide solution. GPC measured the molecular weight of the reaction mixture. w The value is 31700, which is a common polycarboxylate superplasticizer prepared in the laboratory using conventional methods.

[0116] Application Examples

[0117] In the application examples, the cement used is Onoda PⅡ52.5, the mineral powder is S95 type mineral powder produced by Jiangnan Grinding Co., Ltd., the fly ash is Grade I fly ash produced by Jiangsu Huaneng Power Co., Ltd., the sand is medium sand with a fineness modulus M=2.6, and the gravel is basalt with a continuous gradation of 5-20mm particle size.

[0118] Application Example 1:

[0119] Referring to GB / T8077-2000 "Test Method for Homogeneity of Concrete Admixtures", the cement paste fluidity test was conducted on the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer described in this invention to determine its dispersion ability on cement paste. The test mix ratio was: 270g cement, 30g fly ash, and a water-cement ratio of 0.22 to simulate the low water-cement ratio of high-strength concrete. The superplasticizer dosage was maintained at 0.20%. Initial fluidity and fluidity over time were tested, and the results are shown in Table 1.

[0120] Table 1 Results of Cement Mortar Flowability Test

[0121]

[0122]

[0123] As shown in Table 1, compared with the comparative examples, Examples 1-3 have slightly higher initial fluidity, but significantly higher fluidity over time at 30 min, 60 min, and 90 min, indicating that Examples 1-3 have superior slump retention capacity. Examples 4-12 have significantly higher initial and over-time fluidity, indicating excellent water-reducing capacity. In summary, the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer described in this invention exhibits excellent dispersing effect in low water-cement ratio cement pastes.

[0124] Application Example 2:

[0125] To test the dispersion rate of the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer described in this invention, cement mortar fluidity was tested under the following conditions. The dispersion rate was represented by the ratio of the initial fluidity to the fluidity at 10 minutes. A larger ratio indicates a faster dispersion rate, which is more beneficial for ready-mixed concrete manufacturers to shorten mixing time and improve production efficiency. Test conditions: 400g cement, 100g fly ash, 100g mineral powder, 1250g sand, water-cement ratio of 0.35. The polymer dosage was adjusted to achieve a fluidity of 270±10mm at 20 minutes. All materials were stored in a -18℃ freezer for 3 days before use. The test water was maintained at 3–6℃, and the test environment was maintained at 3–6℃. The test results are shown in Table 2.

[0126] Table 2 Results of Cement Mortar Flowability Test

[0127]

[0128]

[0129] As shown in Table 2, the mortar test results indicate that the dispersion rates of Examples 1-12 ranged from 0.85 to 0.99, significantly higher than the 0.7-0.76 of the comparative example. This demonstrates that the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer described in this invention disperses much faster in cement paste than general polycarboxylate superplasticizers. In practical applications, this significantly reduces the phenomenon of increased fluidity, potentially reducing mixing time and improving production efficiency for manufacturers. Furthermore, even with lower dosages than the comparative example, Examples 1-12 exhibited comparable 10-minute fluidity (representing the moment when the polymer is fully adsorbed and exhibits maximum dispersion capacity) to the comparative example, further proving the excellent water-reducing and slump-retaining capabilities of the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer described in this invention.

[0130] Application Example 3:

[0131] Next, the effect of the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer described in this invention on high-strength concrete was tested according to the method specified in GB8076-2008. The dosage of the superplasticizer was adjusted so that the concrete spread at 10 minutes was between 60±2 cm. The concrete mix proportions were: cement 376, mineral powder 105, fly ash 82, silica fume 17, sand 800, aggregate 980, and water 140. The dispersion rate of the superplasticizer on the concrete was quantified by the ratio of the spread of the concrete at the initial stage to that at 10 minutes (when fully dispersed). The viscosity-reducing effect of the superplasticizer on the concrete was quantified by measuring the slump time of the concrete at 10 minutes using a slump cone. The shorter the slump time, the lower the apparent viscosity of the concrete, and the better the viscosity-reducing effect of the polymer. The specific test method for the slump time was as follows: the slump cone was inverted, the bottom was sealed, filled with concrete and smoothed (generally, the inverted slump cone was fixed on a support with the bottom 50 cm off the ground), the bottom cover was quickly slid open, and the slump time of the concrete was measured with a stopwatch. The concrete test results are shown in Table 3.

[0132] Table 3. Test results of high-strength concrete performance

[0133]

[0134]

[0135] Table 3 shows the test results of high-strength concrete: (1) When the dosage of Examples 1 to 12 is lower than that of the comparative example (3.6 to 10.7%), the slump / spread of Examples 1 to 12 is similar to that of the comparative example (approximately 23 / 60cm) at 10 minutes, and the slump / spread of Examples 1 to 12 is significantly greater than that of the comparative example at 1 hour. This indicates that the fast-dispersing and viscosity-reducing polycarboxylate superplasticizer described in this invention has the effect of large water reduction and long slump retention in the application of high-strength concrete; (2) The dispersion speed of Examples 1 to 12 is above 0.9, and the initial and 10-minute fluidity is basically similar. However, the dispersion speed of the comparative example is only about 0.75, and its 10-minute slump / spread shows a significant reverse growth phenomenon. This shows that the dispersion speed of Examples 1 to 12 is fast, which can make the concrete reach a fully dispersed state quickly, save mixing time, improve production efficiency, and have good fluidity control and is not easy to reverse growth; (3) When the air content of Examples 1 to 12 is similar to that of the comparative example, the initial flow time is mostly controlled at 9 minutes. The viscosity of the gradient polymer of the present invention is within 1 second, which is much smaller than the 13 to 16 seconds of the comparative example. This indicates that the gradient polymer of the present invention can effectively reduce the viscosity of high-strength concrete and reduce the difficulty of pumping concrete in actual pouring construction.

Claims

1. A fast-dispersing viscosity-reducing polycarboxylate water reducer, characterized by, The polycarboxylate superplasticizer is a gradient polymer, and its molecular structure is shown in formula (I): （Ⅰ） In equation (Ⅰ), R1 is -H or -CH3; R2 is -CO-, -CH2-, -CH2CH2-, -OCH2CH2-, or -OCH2CH2CH2CH2-; R3 is either -H or -CH3; R4 is -NH2, -NHCH2OH, -OCH2CH2OH, -OCH2CH2CH2OH or -OR7, where R7 is a C1~C4 alkyl group; R5 is -H, -CH3, or -CH2COO - ; R6is -H or -COO - ; a, b, c, d, and n represent the number of repeating units in each repeating unit and are all integers, where a = 2~50, b = 5~140, c = 25~100, d = 5~20, and n = 22~90.

2. The preparation method of the fast-dispersible viscosity-reducing polycarboxylate superplasticizer according to claim 1, characterized in that, The fast-dispersible, viscosity-reducing polycarboxylate superplasticizer is obtained by copolymerization of polyether macromonomers, unsaturated ester monomers, unsaturated acid monomers, and styrene. These monomers are distributed in a stepwise manner on the superplasticizer molecular chain. The polyether macromonomer and unsaturated ester monomer are concentrated on one side of the water-reducing agent molecular chain, wherein the polyether macromonomer serves as a side chain. The unsaturated acid monomers and styrene monomers are concentrated on the other side of the water-reducing agent molecular chain.

3. The preparation method of the fast-dispersible viscosity-reducing polycarboxylate superplasticizer according to claim 2, characterized in that, The specific steps are as follows: (1) Synthesis of prepolymer PC-1: Initiator, catalyst, ligand and monomer A-1 are thoroughly mixed, O2 in the system is removed by N2, the temperature is raised to 80~140℃, and then monomer B-1 is slowly added dropwise. The reaction is carried out for 1~5h to obtain PC-1. The molar ratio of the initiator, catalyst, ligand, monomer A-1, and monomer B-1 is 1:1:1~2:2~40:3~100; (2) Synthesis of prepolymer PC-2: Add monomer A-2 and monomer B-2 to PC-1 obtained in step (1), heat to 100~150℃, and polymerize for 1~5h to obtain PC-2; The molar ratio of monomer A-2, monomer B-2 and catalyst in step (1) is 0~10:2~40:1; (3) Synthesis of fast-dispersible and viscosity-reducing polycarboxylate superplasticizer: Add monomer C and monomer D to PC-2 obtained in step (2), heat to 100~150℃, polymerize for 1~5h, and then filter to remove catalyst and ligand to obtain the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer. The molar ratio of monomer C, monomer D and catalyst in step (1) is 25~100:5~20:1; The monomers A-1 and A-2 mentioned in steps (1) and (2) are polyether macromonomers; The monomers B-1 and B-2 mentioned in steps (1) and (2) are unsaturated esters; The monomer C mentioned in step (3) is an unsaturated acid monomer; The monomer D mentioned in step (3) is styrene.

4. The preparation method of the fast-dispersible viscosity-reducing polycarboxylate superplasticizer according to claim 3, characterized in that, In steps (1) and (2), monomers A-1 and A-2 are independently selected monomers having the following molecular structural formula (Ⅱ): （Ⅱ） In formula (II), n is an integer from 22 to 90, representing the number of repeating units of the repeating unit; R1 is -H or -CH3, and R2 is -CO-, -CH2-, -CH2CH2-, -OCH2CH2- or -OCH2CH2CH2CH2-. The weight-average molecular weights of monomers A-1 and A-2 mentioned in steps (1) and (2) are 1000 to 4000.

5. The preparation method of a fast-dispersible, viscosity-reducing polycarboxylate superplasticizer according to claim 3, characterized in that, In steps (1) and (2), monomers B-1 and B-2 are independently selected from monomers having the following molecular structural formulas: （Ⅲ） In formula (Ⅲ), R3 is -H or -CH3; R4 is -NH2, -NHCH2OH, -OCH2CH2OH, -OCH2CH2CH2OH or -OR7, and R7 is a C1~C4 alkyl group.

6. The preparation method of a fast-dispersible, viscosity-reducing polycarboxylate superplasticizer according to claim 3, characterized in that, The monomer C mentioned in step (3) is selected from any one or more of acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid.

7. The preparation method of the fast-dispersible viscosity-reducing polycarboxylate superplasticizer according to claim 3, characterized in that, The initiator described in step (1) has the following molecular structural formula: （Ⅳ） In the formula, m = 0 or 1; when m = 0, R8 is C6H5-, CH2=CH-, CH2=CHCH2-, HOCH2CH2CH2-, or ; When m=1, R8 is CH3CH2-, HOCH2CH2-, CH2=CHCH2-, C6H5-, or CH2=CH-; R9 is -H or -CH3; R 10 -H or -CH3; X is a chlorine or bromine atom; The catalyst mentioned in step (1) is cuprous chloride or cuprous bromide; The ligand mentioned in step (1) is selected from any one of 2,2'-bipyridine (bpy), 4,4'-dinonyl-2,2'-bipyridine (dNbpy), N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA), tris[2-(dimethylamino)ethyl]amine (Me6TREN), and N,N,N',N'-tetra(2-pyridylmethyl)ethylenediamine (TPEN).

8. The preparation method of the fast-dispersible viscosity-reducing polycarboxylate superplasticizer according to claim 3, characterized in that, In step (1), the weight-average molecular weight of prepolymer PC-1 is 10,000 to 60,000; In step (2), the weight-average molecular weight of prepolymer PC-2 is 15,000 to 70,000; The weight-average molecular weight of the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer described in step (3) is 20,000 to 80,000.

9. The application of the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer of claim 1 as a cement dispersant.

10. The use of the fast-dispersible and viscosity-reducing polycarboxylate superplasticizer according to claim 9, characterized in that, The dosage of the fast-dispersing, viscosity-reducing polycarboxylate superplasticizer is 0.05% to 0.3% of the total cementitious material mass, and the dosage is the pure solid dosage, while the percentage is the mass percentage.

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