Polycarboxylate superplasticizer based on photo-initiation polymerization as well as preparation method and application thereof

Abstract

The invention belongs to the field of building material additives, and discloses a polycarboxylate superplasticizer based on photo-initiation polymerization and a preparation method and application thereof.The preparation method comprises the steps that unsaturated monomers containing epoxy groups and alkylene oxide serve as raw materials, and polymerization is conducted on ultraviolet light with the specific wavelength and a photoinitiator to prepare polyether macromonomers; the bottleneck of the traditional thermocatalytic high-temperature long-time reaction is broken through, a dynamic polymerization network is constructed through photosensitive group density regulation and control, the environmental adaptability is remarkably improved, meanwhile, the energy consumption is reduced, and the method has important industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of building material additives, specifically relating to a polycarboxylate superplasticizer based on photoinitiated polymerization, its preparation method, and its application. Background Technology

[0002] Concrete, as one of the most important structural materials in modern construction, has always had its performance optimization a focus of academic and engineering circles. Polycarboxylate superplasticizers, as highly efficient admixtures, play a crucial role in improving the rheological properties, strength, and durability of concrete. Polyether macromonomers, which are polyoxyethylene-polyoxypropylene coethers containing unsaturated double bonds, are widely used in the synthesis of polycarboxylate superplasticizers (PCE).

[0003] In the existing synthesis of polycarboxylate superplasticizers, the common preparation method for polyether macromonomers is the homopolymerization of ethylene oxide (EO) or random copolymerization with propylene oxide (PO) using alkaline catalysis or thermal catalysis. This method has the advantages of relatively mature reaction conditions and a wide range of raw material sources. However, the bottleneck of the existing technology is that the reaction temperature is usually ≥80℃ and there is a problem of low double bond retention rate. This leads to increased rigidity of the superplasticizer molecular chain, insufficient environmental adaptability, high energy consumption, and a large amount of catalyst residue.

[0004] In recent years, photocatalysis technology has made some progress in the field of polymer synthesis. The polymers prepared show advantages such as low temperature, fast response and tunable structure, but it has not addressed the optimization problems of high temperature dependence and double bond loss in the synthesis of polyether water-reducing agent macromonomers. Summary of the Invention

[0005] The purpose of this invention is to provide a polycarboxylate superplasticizer based on photo-initiated polymerization and its preparation method. The method uses photo-initiated polymerization to prepare polyether macromonomers, which are then obtained by free radical copolymerization. The reaction can be carried out rapidly at low temperature, and the double bond retention rate is as high as 98.1% to 99.8%, which significantly reduces energy consumption and double bond loss rate.

[0006] Another objective of this invention is to provide an application of a photoinitiated polymerization-based polycarboxylate superplasticizer in concrete.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization, the method comprising the following steps:

[0009] 1) Place epoxy monomers, epoxy alkane and photoinitiator in a photoreactor to carry out photo-initiated polymerization to obtain polyether macromonomers;

[0010] 2) The polyether macromonomer, unsaturated acid, unsaturated ester and deionized water are placed in a reaction vessel and mixed evenly. Then, an initiator, a reducing agent and a chain transfer agent are added dropwise to carry out a free radical reaction to obtain the polycarboxylate superplasticizer based on photoinitiated polymerization.

[0011] In step 1), the epoxy monomer is one or more of glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, 1,2-epoxy-4-vinylcyclohexane or 3,4-epoxycyclohexylmethyl methacrylate.

[0012] In step 1), the epoxide is one or more of ethylene oxide or propylene oxide.

[0013] In step 1), the photoinitiator is one or more of diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, 4,4'-dimethyldiphenyliodonium hexafluorophosphate, triphenylthionium hexafluorophosphate, tri-tolylthionium hexafluorophosphate, or tri-tolylthionium trifluoromethanesulfonate.

[0014] In step 1), the molar ratio of the epoxy monomer, epoxy alkane and photoinitiator is 1:25~120:0.01~0.05.

[0015] In step 1), the photo-initiated polymerization reaction takes 2-3 hours, the reaction temperature is 40-60°C, the wavelength of the light is 300-400 nm, and the light intensity is 5-50 W / m². 2 .

[0016] In step 2), the unsaturated acid is one or more of acrylic acid, methacrylic acid, aconitic acid, maleic acid, itaconic acid, dimethylmaleic acid, allyl succinic acid, 2-buten-1-yl succinic acid, or 1,2,3,4-cyclopentenetetracarboxylic acid.

[0017] In step 2), the unsaturated ester is one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, or hydroxybutyl acrylate.

[0018] In step 2), the initiator is one or more of hydrogen peroxide, ammonium persulfate, sodium persulfate, or potassium persulfate.

[0019] In step 2), the reducing agent is one or more of sodium bisulfite, sodium sulfite, sodium formaldehyde sulfoxylate, ascorbic acid, sodium ascorbate, isoascorbic acid, or sodium hypophosphite.

[0020] In step 2), the chain transfer agent is one or more of mercaptoacetic acid, mercaptoethanol, 2-mercaptopropionic acid, 3-mercaptopropionic acid, sodium methacrylate sulfonate, or dodecyl mercaptan.

[0021] In step 2), the molar ratio of the polyether macromonomer, unsaturated acid, unsaturated ester, initiator, reducing agent and chain transfer agent is 1:0~6:0~6:0.01~0.2:0.03~0.2:0.03~0.1.

[0022] In step 2), the free radical reaction takes 2 to 5 hours and the reaction temperature is 15 to 50°C.

[0023] This invention provides a polycarboxylate superplasticizer based on photoinitiated polymerization prepared using the above-described preparation method.

[0024] This invention provides an application of the photoinitiated polymerization-based polycarboxylate superplasticizer in concrete.

[0025] In the preparation method described in this invention, the photoinitiator decomposes after absorbing photons to generate active free radicals, which initiate the ring-opening polymerization of epoxy groups while retaining unsaturated double bonds. Furthermore, the molecular chain growth can be controlled by precisely adjusting the density of photosensitive groups and the light intensity. Polyether macromonomers with a weight-average molecular weight of 1000 g / mol to 8000 g / mol and a double bond retention rate of 98.1% to 99.8% can be obtained within 2 to 3 hours.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. Traditional polyether synthesis relies heavily on high temperatures of ≥80℃ and long reaction times of ≥4h. However, this method introduces photocatalytic polymerization technology, which uses photoinitiators to generate active free radicals under specific wavelength light to initiate polymerization between molecular chains. This breaks away from the limitations of traditional thermal initiation, avoids high-temperature processes, shortens the synthesis reaction time of polyether macromonomers to 2-3 hours, and achieves a double bond retention rate of over 98.1%, making it more environmentally friendly and energy-saving.

[0028] 2. Unlike traditional random copolymerization, the polyether macromonomers prepared by the method described in this invention can have their molecular weight and block structure controlled by light intensity and photosensitive group density, thus overcoming the limitations of traditional random copolymerization.

[0029] 3. This invention optimizes the water-reducing agent by adjusting the degree of polymerization by regulating the light intensity, thus solving the problem of performance degradation of traditional water-reducing agents under high temperature or high salt environment. The water-reducing agent prepared by this invention has excellent performance under the conditions of 50℃ and 5% sulfate. Attached Figure Description

[0030] Figure 1The GPC spectrum of the photoinitiated polymerization-based polycarboxylate superplasticizer prepared in Example 5;

[0031] Figure 2 The GPC spectrum of the photoinitiated polymerization-based polycarboxylate superplasticizer prepared in Example 8 is shown. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0034] The double bond retention rates of the polyether macromonomers or polyether products in the following examples and comparative examples were tested according to standard T / CPCIF0253-2023; the weight-average molecular weight was determined by gel permeation chromatography (GPC), calibrated using polyethylene glycol as a standard. The GPC spectra of Examples 5 and 8 are shown below. Figure 1 and Figure 2 As shown.

[0035] Example 1

[0036] A method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization specifically includes the following steps:

[0037] 1) Under nitrogen protection, 1 mol of glycidyl methacrylate, 50 mol of ethylene oxide, and 0.01 mol of diphenyliodonium hexafluorophosphate were placed in a photoreactor at 40 °C, using 385 nm and 40 W / m 2 Photoinitiated polymerization was carried out under ultraviolet light with light intensity for 2 hours to obtain polyether macromonomers with a double bond retention rate of 99.5% and a weight-average molecular weight of 2400 g / mol.

[0038] 2) 0.1 mol of polyether macromonomer, 0.1 mol of 1,2,3,4-cyclopentenetetracarboxylic acid, and 0.6 mol of ethyl methacrylate were sequentially added to a three-necked flask equipped with a stirrer and a thermometer. Then, 300 mL of deionized water was added, and the mixture was stirred until a homogeneous system was formed. Subsequently, 0.02 mol of ammonium persulfate, 0.003 mol of sodium bisulfite, and 0.003 mol of mercaptoacetic acid were added dropwise. The reaction temperature was maintained at 15 °C, and the reaction was carried out for 5 h. After the reaction was completed, the polycarboxylic acid water-reducing agent based on photoinitiated polymerization was obtained.

[0039] Example 2

[0040] A method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization specifically includes the following steps:

[0041] 1) Under nitrogen protection, 1 mol glycidyl acrylate, 50 mol ethylene oxide, 10 mol propylene oxide, and 0.05 mol 4,4'-dimethyldiphenyliodonium hexafluorophosphate were placed in a photoreactor at 45°C, using 375 nm and 5 W / m 2 Photoinitiated polymerization was carried out under ultraviolet light with light intensity for 2.5 h to obtain polyether macromonomers with a double bond retention rate of 99.6% and a weight-average molecular weight of 3000 g / mol.

[0042] 2) 0.1 mol of polyether macromonomer, 0.6 mol of dimethylmaleic acid, and 0.1 mol of hydroxybutyl acrylate were added sequentially to a three-necked flask equipped with a stirrer and a thermometer. Then, 350 mL of deionized water was added and stirred until a homogeneous system was formed. Subsequently, 0.003 mol of potassium persulfate, 0.015 mol of sodium sulfite, and 0.004 mol of 3-mercaptopropionic acid were added dropwise. The reaction temperature was maintained at 20 °C, and the reaction was carried out for 4 h. After the reaction was completed, the polycarboxylate superplasticizer based on photoinitiated polymerization was obtained.

[0043] Example 3

[0044] A method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization specifically includes the following steps:

[0045] 1) Under nitrogen protection, 1 mol allyl glycidyl ether, 100 mol propylene oxide, and 0.05 mol diphenyliodonium hexafluoroantimonate were placed in a photoreactor at 50°C, using 305 nm and 50 W / m 2 Photoinitiated polymerization was carried out under ultraviolet light for 3 hours to obtain polyether macromonomers with a double bond retention rate of 98.1% and a weight-average molecular weight of 5000 g / mol.

[0046] 2) 0.1 mol of polyether macromonomer, 0.05 mol of acrylic acid, and 0.15 mol of hydroxypropyl acrylate were added sequentially to a three-necked flask equipped with a stirrer and a thermometer. Then, 520 mL of deionized water was added and stirred until a homogeneous system was formed. Subsequently, 0.004 mol of ammonium persulfate, 0.02 mol of sodium formaldehyde sulfoxylate, and 0.005 mol of dodecanethiol were added dropwise. The reaction temperature was maintained at 25 °C and the reaction was carried out for 3.5 h. After the reaction was completed, the polycarboxylate superplasticizer based on photoinitiated polymerization was obtained.

[0047] Example 4

[0048] A method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization specifically includes the following steps:

[0049] 1) Under nitrogen protection, 1 mol of 1,2-epoxy-4-vinylcyclohexane, 100 mol of ethylene oxide, and 0.05 mol of tri-p-tolylthionium trifluoromethane sulfonate were placed in a photoreactor at 55 °C, using 315 nm and 15 W / m 2 Photoinitiated polymerization was carried out under ultraviolet light for 2 hours to obtain polyether macromonomers with a double bond retention rate of 99.8% and a weight-average molecular weight of 5000 g / mol.

[0050] 2) 0.1 mol of polyether macromonomer, 0.25 mol of itaconic acid, and 0.2 mol of ethyl acrylate were added sequentially to a three-necked flask equipped with a stirrer and a thermometer. Then, 550 mL of deionized water was added and stirred until a homogeneous system was formed. Subsequently, 0.005 mol of hydrogen peroxide, 0.01 mol of ascorbic acid, and 0.006 mol of sodium methpropylene sulfonate were added dropwise. The reaction temperature was maintained at 30 °C, and the reaction was carried out for 3 hours. After the reaction was completed, the polycarboxylate superplasticizer based on photoinitiated polymerization was obtained.

[0051] Example 5

[0052] A method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization specifically includes the following steps:

[0053] 1) Under nitrogen protection, 1 mol of 3,4-epoxycyclohexylmethyl methacrylate, 50 mol of ethylene oxide, 5 mol of propylene oxide, and 0.03 mol of tri-p-tolylthionium hexafluorophosphate were placed in a photoreactor at 60℃, using 300 nm and 45 W / m 2 Photoinitiated polymerization was carried out under ultraviolet light for 2 hours to obtain polyether macromonomers with a double bond retention rate of 99.6% and a weight-average molecular weight of 2700 g / mol.

[0054] 2) 0.1 mol of polyether macromonomer, 0.3 mol of maleic acid, and 0.1 mol of methyl acrylate were added sequentially to a three-necked flask equipped with a stirrer and a thermometer. Then, 300 mL of deionized water was added and stirred until a homogeneous system was formed. Subsequently, 0.005 mol of sodium persulfate, 0.007 mol of ascorbic acid, and 0.007 mol of 2-mercaptopropionic acid were added dropwise. The reaction temperature was maintained at 35 °C and the reaction was carried out for 3 h. After the reaction was completed, the polycarboxylate superplasticizer based on photoinitiated polymerization was obtained.

[0055] Example 6

[0056] A method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization specifically includes the following steps:

[0057] 1) Under nitrogen protection, 1 mol glycidyl acrylate, 5 mol ethylene oxide, 100 mol propylene oxide, and 0.05 mol triphenylthionium hexafluorophosphate were placed in a photoreactor at 40°C, using 345 nm and 40 W / m 2 Photoinitiated polymerization was carried out under ultraviolet light for 3 hours to obtain polyether macromonomers with a double bond retention rate of 99.4% and a weight-average molecular weight of 8000 g / mol.

[0058] 2) 0.1 mol of polyether macromonomer, 0.1 mol of aconitic acid, and 0.2 mol of methyl acrylate were added sequentially to a three-necked flask equipped with a stirrer and a thermometer. Then, 830 mL of deionized water was added and stirred until a homogeneous system was formed. Subsequently, 0.003 mol of ammonium persulfate, 0.006 mol of sodium hypophosphite, and 0.008 mol of 3-mercaptopropionic acid were added dropwise. The reaction temperature was maintained at 40 °C and the reaction was carried out for 2.5 h. After the reaction was completed, the polycarboxylate superplasticizer based on photoinitiated polymerization was obtained.

[0059] Example 7

[0060] A method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization specifically includes the following steps:

[0061] 1) Under nitrogen protection, 1 mol allyl glycidyl ether, 50 mol ethylene oxide, 50 mol propylene oxide, and 0.05 mol tri-p-tolylthionium hexafluorophosphate were placed in a photoreactor at 60℃, using 365 nm and 30 W / m 2 Photoinitiated polymerization was carried out under ultraviolet light for 3 hours to obtain polyether macromonomers with a double bond retention rate of 99.6% and a weight-average molecular weight of 5000 g / mol.

[0062] 2) 0.1 mol of polyether macromonomer, 0.2 mol of acrylic acid, and 0.6 mol of hydroxyethyl acrylate were added sequentially to a three-necked flask equipped with a stirrer and a thermometer. Then, 550 mL of deionized water was added and stirred until a homogeneous system was formed. Subsequently, 0.001 mol of sodium persulfate, 0.004 mol of isoascorbic acid, and 0.009 mol of mercaptoacetic acid were added dropwise. The reaction temperature was maintained at 40 °C, and the reaction was carried out for 2.5 h. After the reaction was completed, the polycarboxylate superplasticizer based on photoinitiated polymerization was obtained.

[0063] Example 8

[0064] A method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization specifically includes the following steps:

[0065] 1) Under nitrogen protection, 1 mol glycidyl methacrylate, 25 mol ethylene oxide, and 0.01 mol 4,4'-dimethyldiphenyliodonium hexafluorophosphate were placed in a photoreactor at 50℃, using 400 nm and 25 W / m 2 Photoinitiated polymerization was carried out under ultraviolet light for 2 hours to obtain polyether macromonomers with a double bond retention rate of 99.1% and a weight-average molecular weight of 1000 g / mol.

[0066] 2) 0.1 mol of polyether macromonomer and 0.6 mol of acrylic acid were added sequentially to a three-necked flask equipped with a stirrer and a thermometer, followed by 150 mL of deionized water. The mixture was stirred until a homogeneous system was formed. Then, 0.001 mol of hydrogen peroxide, 0.003 mol of sodium ascorbate and 0.01 mol of mercaptoacetic acid were added dropwise. The reaction temperature was maintained at 50 °C and the reaction was carried out for 2 h. After the reaction was completed, the polycarboxylate superplasticizer based on photoinitiated polymerization was obtained.

[0067] Comparative Example 1

[0068] A method for preparing a polycarboxylate superplasticizer specifically includes the following steps:

[0069] 0.1 mol isopentenyl alcohol polyoxyethylene ether (molecular weight 3000 g / mol), 0.6 mol dimethyl maleic acid, and 0.1 mol hydroxybutyl acrylate were sequentially added to a three-necked flask equipped with a stirrer and thermometer. Then, 350 mL of deionized water was added, and the mixture was stirred until a homogeneous system was obtained. Subsequently, 0.003 mol potassium persulfate, 0.015 mol sodium sulfite, and 0.004 mol 3-mercaptopropionic acid were added dropwise. The reaction temperature was maintained at 20 °C, and the reaction was carried out for 4 hours. After the reaction was completed, a polycarboxylate superplasticizer was obtained.

[0070] Comparative Example 2

[0071] A method for preparing a polyether product specifically includes the following steps:

[0072] Under nitrogen protection, 25 mol of ethylene oxide and 0.01 mol of 4,4'-dimethyldiphenyliodonium hexafluorophosphate were placed in a photoreactor at 50 °C, using 400 nm and 25 W / m 2 Photoinitiated polymerization was carried out under ultraviolet light for 2 hours to obtain a polyether product with a double bond retention rate of 0 and a weight-average molecular weight of 980 g / mol. It cannot be used as a polyether macromonomer to synthesize a water-reducing agent.

[0073] The polycarboxylate superplasticizers prepared in the above embodiments are used for cement paste fluidity and concrete testing, as detailed below:

[0074] Neat cement paste fluidity test: The test temperature was 50℃. Referring to GB / T 8077-2023 "Test Method for Homogeneity of Concrete Admixtures", the fluidity of the neat cement paste obtained in Examples 1-8 was tested. The water-cement ratio (W / C) was 0.29, the sodium sulfate content was 5% of the cement weight, and the admixture dosage (converted to solids) was 0.10% of the cement weight. No loss of fluidity was observed in the neat cement paste within 5 hours. The test results are shown in Table 1.

[0075] Table 1. Flowability and loss over time of different samples of paste

[0076]

[0077] Concrete performance testing: The test temperature was 50℃. Slump loss and concrete strength were tested on the samples obtained in Examples 1 to 8 according to GB / T 8076-2025 "Concrete Admixtures". The sodium sulfate content was 5% of the cement content. When the admixture dosage relative to the cement content was 1.5%, the 1-day compressive strength increased by more than 95%, and the 3-day compressive strength increased by more than 70%. The test results are shown in Table 2.

[0078] Table 2. Slump retention and mechanical properties of concrete samples from different samples

[0079]

[0080] The polycarboxylate superplasticizer prepared by this invention is suitable for concrete in extreme environments such as high temperature and high salt. It has excellent performance and stable product performance, good slump retention performance, and can improve the mechanical properties of concrete.

[0081] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0082] The above description of the embodiments is intended to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a polycarboxylate superplasticizer based on photoinitiated polymerization, characterized in that, The preparation method includes the following steps: 1) Place epoxy monomers, epoxy alkane and photoinitiator in a photoreactor to carry out photo-initiated polymerization to obtain polyether macromonomers; 2) The polyether macromonomer, unsaturated acid, unsaturated ester and deionized water are placed in a reaction vessel and mixed evenly. Then, an initiator, a reducing agent and a chain transfer agent are added dropwise to carry out a free radical reaction to obtain the polycarboxylate superplasticizer based on photoinitiated polymerization.

2. The preparation method according to claim 1, characterized in that, In step 1), the epoxy monomer is one or more of glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, 1,2-epoxy-4-vinylcyclohexane or 3,4-epoxycyclohexylmethyl methacrylate; the epoxy alkane is one or more of ethylene oxide or propylene oxide.

3. The preparation method according to claim 1, characterized in that, In step 1), the photoinitiator is one or more of diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, 4,4'-dimethyldiphenyliodonium hexafluorophosphate, triphenylthionium hexafluorophosphate, tri-tolylthionium hexafluorophosphate, or tri-tolylthionium trifluoromethanesulfonate.

4. The preparation method according to any one of claims 1-3, characterized in that, In step 1), the molar ratio of the epoxy monomer, epoxy alkane and photoinitiator is 1:25~120:0.01~0.

05.

5. The preparation method according to claim 1, characterized in that, In step 1), the photo-initiated polymerization reaction takes 2-3 hours, the reaction temperature is 40-60°C, the wavelength of the light is 300-400 nm, and the light intensity is 5-50 W / m². 2 .

6. The preparation method according to claim 1, characterized in that, In step 2), the unsaturated acid is one or more of acrylic acid, methacrylic acid, aconitic acid, maleic acid, itaconic acid, dimethylmaleic acid, allyl succinic acid, 2-buten-1-ylsuccinic acid, or 1,2,3,4-cyclopentenetetracarboxylic acid; the unsaturated ester is one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, or hydroxybutyl acrylate; the initiator is one or more of hydrogen peroxide, ammonium persulfate, sodium persulfate, or potassium persulfate; the reducing agent is one or more of sodium bisulfite, sodium sulfite, sodium formaldehyde sulfoxylate, ascorbic acid, sodium ascorbate, isoascorbic acid, or sodium hypophosphite; and the chain transfer agent is one or more of mercaptoacetic acid, mercaptoethanol, 2-mercaptopropionic acid, 3-mercaptopropionic acid, sodium methacrylate sulfonate, or dodecyl mercaptoethanol.

7. The preparation method according to claim 1 or 6, characterized in that, In step 2), the molar ratio of the polyether macromonomer, unsaturated acid, unsaturated ester, initiator, reducing agent and chain transfer agent is 1:0~6:0~6:0.01~0.2:0.03~0.2:0.03~0.

1.

8. The preparation method according to claim 1, characterized in that, In step 2), the free radical reaction takes 2 to 5 hours and the reaction temperature is 15 to 50°C.

9. A polycarboxylate superplasticizer based on photoinitiated polymerization prepared by the preparation method as described in claim 1.

10. The application of a photoinitiated polymerization-based polycarboxylate superplasticizer as described in claim 9 in concrete.

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