A primary polyether, its preparation and use

Abstract

The application provides a primary polyether, a preparation method and application thereof, and belongs to the technical field of water reducing agents. After a catalytic esterification reaction of pentaerythritol and 2,2-dimethylol propionic acid, the primary polyether is prepared by the following steps: reacting with a polyether macromonomer and maleic anhydride to obtain a carboxyl-terminated polyether macromonomer mixed esterification reaction, further reacting with sulfamic acid, then reacting with graphene oxide, and finally mixing with intercalated montmorillonite. The primary polyether prepared by the application has a large three-dimensional structure volume, avoids cement particle flocculation, has dispersibility and mud resistance, can improve the mechanical properties of a cement-based material, realizes slow-release function, controls the release rate of polyether monomers, improves dispersion and retention capacity, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of water-reducing agent technology, specifically to a primary polyether, its preparation method, and its application. Background Technology

[0002] Despite the widespread application of high-performance concrete technology, as the service environment of concrete deteriorates, its inherent performance defects under extreme conditions become increasingly apparent, particularly the durability of concrete structures, which requires in-depth research. For example, in marine engineering concrete, which suffers from cracking and steel corrosion, improving the chloride ion penetration resistance of concrete remains a major challenge.

[0003] Primary polyethers, also known as polyether macromonomers, are important raw materials for the synthesis of polycarboxylate superplasticizers. Their molecular structure is a key factor affecting the performance of polycarboxylate superplasticizers. In recent years, the polyether macromonomer market has continued to develop, and the product structure has undergone significant changes. Numerous new functionalized polyether macromonomer products have emerged, fully reflecting the rapid development of the polycarboxylate superplasticizer macromonomer industry chain and the continuous improvement of product quality. However, the market's performance requirements for polycarboxylate superplasticizers are becoming increasingly stringent. While current polyether macromonomers can meet most requirements, they still have defects and shortcomings, such as poor resistance to mud. Therefore, further improvements in the performance of polycarboxylate superplasticizers are needed. Furthermore, research on polyether macromonomers with special molecular structures is limited, making it difficult to meet the demands, such as those required for ultra-high performance concrete.

[0004] Cement-based materials are multi-material, multi-scale composites. Among them, the hydration product, calcium silicate gel, possesses nanoscale characteristics, with over 90% of its pores being nanoscale. Combined with Academician Wu Zhongwei's four-class pore size classification method, the emergence of nanomaterials provides another approach to the preparation of high-performance cement-based materials. Small-sized nanoparticles can fill some of the micropores in cement paste, improving the microstructure of the concrete interface, thereby enhancing the strength and durability of concrete. Currently, research on nanomaterials in concrete is still in its early stages, with many challenges in both theoretical and practical applications. Summary of the Invention

[0005] The purpose of this invention is to propose a primary polyether, its preparation method, and its application. The three-dimensional structure has a large volume, which avoids cement particle flocculation, balances dispersibility and anti-mud properties, improves the mechanical properties of cement-based materials, and realizes a slow-release function, thereby controlling the release rate of polyether monomers and improving dispersion retention ability, and has broad application prospects.

[0006] The technical solution of this invention is implemented as follows:

[0007] This invention provides a method for preparing a primary polyether, wherein pentaerythritol and 2,2-dimethylolpropionic acid are subjected to a catalytic esterification reaction, followed by a reaction with a polyether macromonomer and maleic anhydride to obtain a mixed esterification reaction of a carboxyl-terminated polyether macromonomer, and then further reacted with aminosulfonic acid, followed by a reaction with graphene oxide, and finally mixed with intercalated montmorillonite to obtain a primary polyether.

[0008] As a further improvement to the present invention, the following steps are included:

[0009] S1. A catalytic esterification reaction of pentaerythritol and 2,2-dimethylolpropionic acid was carried out to obtain a hydroxyl-terminated hyperbranched polyester.

[0010] S2. The polyether macromonomer is reacted with maleic anhydride to obtain a carboxyl-terminated polyether macromonomer;

[0011] S3. A hyperbranched macromonomer is prepared by catalytic esterification of a carboxyl-terminated polyether macromonomer and a hydroxyl-terminated hyperbranched polyester.

[0012] S4. Mix hyperbranched macromonomer and aminosulfonic acid, add urea, heat the reaction under inert gas protection, add ethanol to dissolve, filter, remove solvent from filtrate under reduced pressure to obtain sulfonate grafted hyperbranched macromonomer.

[0013] S5. Dissolve octadecyl dimethyl benzyl ammonium chloride in water, add sodium montmorillonite, heat and stir to intercalate, and obtain intercalated montmorillonite;

[0014] S6. Graphene oxide is uniformly dispersed in water, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide are added, the mixture is stirred and activated, sulfonate-grafted hyperbranched macromonomers are added, the mixture is heated and stirred to react, intercalated montmorillonite is added, the mixture is heated and stirred, filtered, washed, and dried to obtain primary polyether.

[0015] As a further improvement of the present invention, the molar ratio of pentaerythritol and 2,2-dimethylolpropionic acid in step S1 is 1:5-8, and a catalyst is added, namely p-toluenesulfonic acid, the amount of the catalyst added is 3-5 wt% of pentaerythritol, the reaction temperature is 120-140℃, and the time is 4-6 h.

[0016] As a further improvement of the present invention, the molar ratio of the polyether macromonomer and maleic anhydride in step S2 is 1.5-2.5:1, and a catalyst is added, namely 4-dimethylaminopyridine. The reaction temperature is 80-90°C and the reaction time is 5-7 h. The polyether macromonomer is allyl polyoxyethylene ether, methyl allyl polyoxyethylene ether, or isopentenyl polyoxyethylene ether.

[0017] As a further improvement of the present invention, in step S3, the mass ratio of the terminal carboxyl polyether macromonomer to the terminal hydroxyl hyperbranched polyester is 7-10:5, and a catalyst is added, which is p-toluenesulfonic acid or concentrated sulfuric acid. The amount of catalyst added is 3-5 wt% of the terminal hydroxyl hyperbranched polyester, the reaction temperature is 110-130℃, and the time is 5-7 h.

[0018] As a further improvement of the present invention, the mass ratio of the hyperbranched macromonomer to aminosulfonic acid in step S4 is 10:0.5-1, the reaction temperature is 135-145℃, and the reaction time is 4-6h.

[0019] As a further improvement of the present invention, the mass ratio of octadecyl dimethyl benzyl ammonium chloride to sodium montmorillonite in step S5 is 2-3:10, and the heating and stirring intercalation temperature is 45-55°C for 1-3 hours.

[0020] As a further improvement of the present invention, the mass ratio of graphene oxide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, sulfonate-grafted hyperbranched macromonomer, and intercalated montmorillonite in step S6 is 3-5:1-2:1-2:10-12:25-35, the temperature of the heating and stirring reaction is 45-55℃, the time is 2-4h, and the heating and stirring time is 0.5-1.5h.

[0021] The present invention further protects a primary polyether prepared by the above-described preparation method.

[0022] This invention further protects the application of the above-mentioned primary polyether in the preparation of concrete water-reducing agents.

[0023] The present invention has the following beneficial effects:

[0024] Traditional polyether-based water-reducing agents mostly have a comb-like structure, which is easily adsorbed into the interlayer of clay and has poor anti-mud properties. Therefore, the primary polyether obtained in this invention first uses a hydroxyl-terminated hyperbranched polyester as the core, and then reacts it with a carboxyl-terminated polyether macromonomer to obtain a hyperbranched macromonomer, changing the molecular chain to a hyperbranched structure. This three-dimensional structure has a large volume and a significant anti-mud effect. At the same time, the hyperbranched structure can also enhance steric hindrance, avoid cement particle flocculation, and balance dispersibility and anti-mud properties.

[0025] This invention reacts the residual hydroxyl groups on hyperbranched macromonomers with aminosulfonic acid to introduce strongly ionized sulfonic acid groups, giving the molecule a high negative charge density. The introduction of sulfonic acid groups enhances the rigidity of the main chain, reduces molecular chain curling, and simultaneously increases the overall charge density of the main chain, strengthening the bond between the main chain and the Ca on the surface of cement particles. 2+ It enhances the binding ability of cement, improves the selective adsorption of cement, and reduces the probability of adsorption by clay.

[0026] This invention utilizes graphene oxide activated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide, which then reacts with sulfonate-grafted hyperbranched macromonomers. The carboxyl functional groups on the graphene oxide surface react with the hydration product calcium hydroxide, allowing the graphene oxide to interconnect within the cement hydration products, forming a three-dimensional network structure to improve the mechanical properties of cement-based materials. Due to its thin mesh effect and migration effect, two-dimensional graphene materials can enrich the graphene at the interface between aggregates and cementitious materials, providing more nucleation sites and achieving a stronger bridging effect. Simultaneously, graphene materials can adsorb interlayer water at the interface, reducing the water-cement ratio and improving the interface microstructure. Graphene oxide exhibits a template effect during cement hydration, utilizing numerous nucleation sites on its surface to form thick rod-shaped and flower-like hydration crystals. When columnar crystals grow in pores, cracks, or loose structures within the hydration products, they freely grow to form flower-like crystals. These crystals act as fillers and crack-resistant components in pores and cracks, delaying crack propagation. Furthermore, graphene oxide can provide nucleation sites, promoting the growth of hydrated calcium silicate, calcium hydroxide, and ettringite.

[0027] Finally, the present invention mixes and stirs the organically intercalated montmorillonite with the final product, and introduces the hyperbranched macromonomer into the interlayer through electrostatic interaction and hydrogen bonding to form a "sandwich" structure, thereby achieving a slow-release function, controlling the release rate of polyether monomers, improving dispersion and retention capacity, and the quaternary ammonium salt modified montmorillonite can preferentially adsorb free clay ions, reduce the consumption of polyether by clay, and solve the "failure" problem of traditional water-reducing agents in manufactured sand.

[0028] The primary polyether stereostructure obtained by this invention has a large volume, which avoids cement particle flocculation, takes into account both dispersibility and anti-mud properties, improves the mechanical properties of cement-based materials, realizes the slow-release function, thereby controlling the release rate of polyether monomers, improving dispersion and retention ability, and has broad application prospects. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0030] Graphene oxide, sheet diameter, 2-4 μm, thickness 0.8-1.2 nm.

[0031] Example 1

[0032] This embodiment provides a method for preparing a primary polyether, including the following steps:

[0033] S1. 0.1 mol pentaerythritol and 0.5 mol 2,2-dimethylolpropionic acid were added to 200 mL of dimethyl sulfoxide and stirred until homogeneous. Under nitrogen protection, 3 wt% of p-toluenesulfonic acid (based on the amount of pentaerythritol) was added, and the mixture was heated to 120 °C and stirred for 4 h. Toluene was added for recrystallization, and the mixture was filtered, washed, and dried to obtain a hydroxyl-terminated hyperbranched polyester.

[0034] S2. Mix 0.15 mol allyl polyoxyethylene ether and 0.1 mol maleic anhydride, add 2 wt% of 4-dimethylaminopyridine as the polyether macromonomer under nitrogen protection, heat to 80 °C, stir and react for 5 h, dissolve the product in dichloromethane, wash with water, remove the solvent under reduced pressure, and obtain the carboxyl-terminated polyether macromonomer.

[0035] S3. Dissolve 7g of carboxyl-terminated polyether macromonomer and 5g of hydroxyl-terminated hyperbranched polyester in 150mL of N,N-dimethylformamide. Under nitrogen protection, add 3wt% p-toluenesulfonic acid of the hydroxyl-terminated hyperbranched polyester, heat to 110℃, and stir for 5h to obtain the hyperbranched macromonomer.

[0036] S4. Mix 10g of hyperbranched macromonomer and 0.5g of aminosulfonic acid, add 50g of urea, heat to 135℃ under nitrogen protection, stir and react for 4h, cool to room temperature, add ethanol to dissolve, filter, remove solvent from filtrate under reduced pressure to obtain sulfonate grafted hyperbranched macromonomer.

[0037] S5. Dissolve 2g of octadecyl dimethyl benzyl ammonium chloride in 100mL of water, add 10g of sodium montmorillonite, heat to 45℃, stir and intercalate for 1h, filter, wash, and dry to obtain intercalated montmorillonite.

[0038] S6. 3g of graphene oxide was uniformly dispersed in 500mL of water, 1g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 1g of N-hydroxysuccinimide were added, and the mixture was stirred and activated for 30min. 10g of sulfonate-grafted hyperbranched macromonomer was added, and the mixture was heated to 45℃ and stirred for 2h. 25g of intercalated montmorillonite was added, and the mixture was heated and stirred for 0.5h. The mixture was filtered, washed, and dried to obtain the primary polyether.

[0039] Infrared spectral analysis revealed a value at 3428 cm⁻¹. -1 There is a distinct -NH absorption peak at 3410 cm⁻¹. -1 A strong and broad characteristic absorption peak of -OH appears nearby, at 2868 cm⁻¹. -1 The peak of the stretching vibration of -CH2- is at 1657 cm⁻¹. -1 There are obvious -C=C- absorption peaks at 1480 cm⁻¹. -1 There is a distinct -C=O absorption peak at 1355 cm⁻¹. -1There is a distinct -S=O absorption peak at 1495 cm⁻¹. -1 The absorption peak for the stretching vibration of -CN is located at 1093 cm⁻¹. -1 1078cm -1 and 1051cm -1 The peak at 915-1100 cm⁻¹ is the stretching vibration peak of -CH₂-O-CH₂-. -1 The peaks are the -SiO stretching vibration peaks of layered aluminosilicates, indicating that the compound was successfully synthesized.

[0040] Example 2

[0041] This embodiment provides a method for preparing a primary polyether, including the following steps:

[0042] S1. 0.1 mol pentaerythritol and 0.8 mol 2,2-dimethylolpropionic acid were added to 200 mL of dimethyl sulfoxide and stirred until homogeneous. Under nitrogen protection, 5 wt% of p-toluenesulfonic acid (based on the amount of pentaerythritol) was added, and the mixture was heated to 140 °C and stirred for 6 h. Toluene was added for recrystallization, and the mixture was filtered, washed, and dried to obtain a hydroxyl-terminated hyperbranched polyester.

[0043] S2. Mix 0.25 mol of methyl allyl polyoxyethylene ether and 0.1 mol of maleic anhydride, add 3 wt% of 4-dimethylaminopyridine as the polyether macromonomer under nitrogen protection, heat to 90 °C, stir and react for 7 h, dissolve the product in dichloromethane, wash with water, remove the solvent under reduced pressure, and obtain the carboxyl-terminated polyether macromonomer.

[0044] S3. Dissolve 10g of carboxyl-terminated polyether macromonomer and 5g of hydroxyl-terminated hyperbranched polyester in 150mL of N,N-dimethylformamide. Under nitrogen protection, add 5wt% concentrated sulfuric acid of the hydroxyl-terminated hyperbranched polyester, heat to 130℃, and stir for 7h to obtain the hyperbranched macromonomer.

[0045] S4. Mix 10g of hyperbranched macromonomer and 1g of aminosulfonic acid, add 50g of urea, heat to 145℃ under nitrogen protection, stir for 6h, cool to room temperature, add ethanol to dissolve, filter, remove solvent from filtrate under reduced pressure to obtain sulfonate grafted hyperbranched macromonomer.

[0046] S5. Dissolve 3g of octadecyl dimethyl benzyl ammonium chloride in 100mL of water, add 10g of sodium montmorillonite, heat to 55℃, stir and intercalate for 3h, filter, wash, and dry to obtain intercalated montmorillonite.

[0047] S6. Disperse 5g of graphene oxide evenly in 500mL of water, add 2g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 2g of N-hydroxysuccinimide, stir and activate for 30min, add 12g of sulfonate-grafted hyperbranched macromonomer, heat to 55℃, stir and react for 4h, add 35g of intercalated montmorillonite, heat and stir for 1.5h, filter, wash, and dry to obtain primary polyether.

[0048] Example 3

[0049] This embodiment provides a method for preparing a primary polyether, including the following steps:

[0050] S1. 0.1 mol pentaerythritol and 0.65 mol 2,2-dimethylolpropionic acid were added to 200 mL of dimethyl sulfoxide and stirred until homogeneous. Under nitrogen protection, 4 wt% of p-toluenesulfonic acid (based on the amount of pentaerythritol) was added, and the mixture was heated to 130 °C and stirred for 5 h. Toluene was added for recrystallization, and the mixture was filtered, washed, and dried to obtain a hydroxyl-terminated hyperbranched polyester.

[0051] S2. Mix 0.2 mol isopentenyl polyoxyethylene ether and 0.1 mol maleic anhydride, add 2.5 wt% of 4-dimethylaminopyridine as the polyether macromonomer under nitrogen protection, heat to 85 °C, stir and react for 6 h, dissolve the product in dichloromethane, wash with water, remove the solvent under reduced pressure to obtain the carboxyl-terminated polyether macromonomer.

[0052] S3. Dissolve 8.5g of carboxyl-terminated polyether macromonomer and 5g of hydroxyl-terminated hyperbranched polyester in 150mL of N,N-dimethylformamide. Under nitrogen protection, add 4wt% p-toluenesulfonic acid of the hydroxyl-terminated hyperbranched polyester, heat to 120℃, and stir for 6h to obtain the hyperbranched macromonomer.

[0053] S4. Mix 10g of hyperbranched macromonomer and 0.7g of aminosulfonic acid, add 50g of urea, heat to 140℃ under nitrogen protection, stir for 5h, cool to room temperature, add ethanol to dissolve, filter, remove solvent from filtrate under reduced pressure to obtain sulfonate grafted hyperbranched macromonomer.

[0054] S5. Dissolve 2.5g of octadecyl dimethyl benzyl ammonium chloride in 100mL of water, add 10g of sodium montmorillonite, heat to 50℃, stir and intercalate for 2h, filter, wash, and dry to obtain intercalated montmorillonite;

[0055] S6. 4g of graphene oxide was uniformly dispersed in 500mL of water, 1.5g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 1.5g of N-hydroxysuccinimide were added, and the mixture was stirred and activated for 30min. 11g of sulfonate-grafted hyperbranched macromonomer was added, and the mixture was heated to 50℃ and stirred for 3h. 30g of intercalated montmorillonite was added, and the mixture was heated and stirred for 1h. The mixture was filtered, washed, and dried to obtain the primary polyether.

[0056] Comparative Example 1

[0057] The difference from Example 3 is that steps S1, S3, and S4 were not performed.

[0058] Includes the following steps:

[0059] S1. Mix 0.2 mol isopentenyl polyoxyethylene ether and 0.1 mol maleic anhydride, add 2.5 wt% of 4-dimethylaminopyridine as the polyether macromonomer under nitrogen protection, heat to 85 °C, stir and react for 6 h, dissolve the product in dichloromethane, wash with water, remove the solvent under reduced pressure, and obtain the carboxyl-terminated polyether macromonomer.

[0060] S2. Dissolve 2.5g of octadecyl dimethyl benzyl ammonium chloride in 100mL of water, add 10g of sodium montmorillonite, heat to 50℃, stir and intercalate for 2h, filter, wash, and dry to obtain intercalated montmorillonite;

[0061] S3. 11g of carboxyl-terminated polyether macromonomer was uniformly dispersed in 500mL of water, 1.5g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 1.5g of N-hydroxysuccinimide were added, and the mixture was stirred and activated for 30min. 4g of graphene oxide was added, and the mixture was heated to 50℃ and stirred for 3h. 30g of intercalated montmorillonite was added, and the mixture was heated and stirred for 1h. The mixture was filtered, washed, and dried to obtain the primary polyether.

[0062] Comparative Example 2

[0063] The difference from Example 3 is that step S4 was not performed.

[0064] Includes the following steps:

[0065] S1. 0.1 mol pentaerythritol and 0.65 mol 2,2-dimethylolpropionic acid were added to 200 mL of dimethyl sulfoxide and stirred until homogeneous. Under nitrogen protection, 4 wt% of p-toluenesulfonic acid (based on the amount of pentaerythritol) was added, and the mixture was heated to 130 °C and stirred for 5 h. Toluene was added for recrystallization, and the mixture was filtered, washed, and dried to obtain a hydroxyl-terminated hyperbranched polyester.

[0066] S2. Mix 0.2 mol isopentenyl polyoxyethylene ether and 0.1 mol maleic anhydride, add 2.5 wt% of 4-dimethylaminopyridine as the polyether macromonomer under nitrogen protection, heat to 85 °C, stir and react for 6 h, dissolve the product in dichloromethane, wash with water, remove the solvent under reduced pressure to obtain the carboxyl-terminated polyether macromonomer.

[0067] S3. Dissolve 8.5g of carboxyl-terminated polyether macromonomer and 5g of hydroxyl-terminated hyperbranched polyester in 150mL of N,N-dimethylformamide. Under nitrogen protection, add 4wt% p-toluenesulfonic acid of the hydroxyl-terminated hyperbranched polyester, heat to 120℃, and stir for 6h to obtain the hyperbranched macromonomer.

[0068] S4. Dissolve 2.5g of octadecyl dimethyl benzyl ammonium chloride in 100mL of water, add 10g of sodium montmorillonite, heat to 50℃, stir and intercalate for 2h, filter, wash, and dry to obtain intercalated montmorillonite;

[0069] S5. 4g of graphene oxide was uniformly dispersed in 500mL of water, 1.5g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 1.5g of N-hydroxysuccinimide were added, and the mixture was stirred and activated for 30min. 11g of hyperbranched macromonomer was added, and the mixture was heated to 50℃ and stirred for 3h. 30g of intercalated montmorillonite was added, and the mixture was heated and stirred for 1h. The mixture was filtered, washed, and dried to obtain the primary polyether.

[0070] Comparative Example 3

[0071] The difference from Example 3 is that graphene oxide was not added in step S6.

[0072] Includes the following steps:

[0073] S1. 0.1 mol pentaerythritol and 0.65 mol 2,2-dimethylolpropionic acid were added to 200 mL of dimethyl sulfoxide and stirred until homogeneous. Under nitrogen protection, 4 wt% of p-toluenesulfonic acid (based on the amount of pentaerythritol) was added, and the mixture was heated to 130 °C and stirred for 5 h. Toluene was added for recrystallization, and the mixture was filtered, washed, and dried to obtain a hydroxyl-terminated hyperbranched polyester.

[0074] S2. Mix 0.2 mol isopentenyl polyoxyethylene ether and 0.1 mol maleic anhydride, add 2.5 wt% of 4-dimethylaminopyridine as the polyether macromonomer under nitrogen protection, heat to 85 °C, stir and react for 6 h, dissolve the product in dichloromethane, wash with water, remove the solvent under reduced pressure to obtain the carboxyl-terminated polyether macromonomer.

[0075] S3. Dissolve 8.5g of carboxyl-terminated polyether macromonomer and 5g of hydroxyl-terminated hyperbranched polyester in 150mL of N,N-dimethylformamide. Under nitrogen protection, add 4wt% p-toluenesulfonic acid of the hydroxyl-terminated hyperbranched polyester, heat to 120℃, and stir for 6h to obtain the hyperbranched macromonomer.

[0076] S4. Mix 10g of hyperbranched macromonomer and 0.7g of aminosulfonic acid, add 50g of urea, heat to 140℃ under nitrogen protection, stir for 5h, cool to room temperature, add ethanol to dissolve, filter, remove solvent from filtrate under reduced pressure to obtain sulfonate grafted hyperbranched macromonomer.

[0077] S5. Dissolve 2.5g of octadecyl dimethyl benzyl ammonium chloride in 100mL of water, add 10g of sodium montmorillonite, heat to 50℃, stir and intercalate for 2h, filter, wash, and dry to obtain intercalated montmorillonite;

[0078] S6. Add 1.5g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 1.5g of N-hydroxysuccinimide to 500mL of water, stir and activate for 30min, add 11g of sulfonate-grafted hyperbranched macromonomer, heat to 50℃, stir and react for 3h, add 30g of intercalated montmorillonite, heat and stir for 1h, filter, wash, and dry to obtain primary polyether.

[0079] Comparative Example 4

[0080] The difference from Example 3 is that no intercalated montmorillonite was added in step S6.

[0081] Includes the following steps:

[0082] S1. 0.1 mol pentaerythritol and 0.65 mol 2,2-dimethylolpropionic acid were added to 200 mL of dimethyl sulfoxide and stirred until homogeneous. Under nitrogen protection, 4 wt% of p-toluenesulfonic acid (based on the amount of pentaerythritol) was added, and the mixture was heated to 130 °C and stirred for 5 h. Toluene was added for recrystallization, and the mixture was filtered, washed, and dried to obtain a hydroxyl-terminated hyperbranched polyester.

[0083] S2. Mix 0.2 mol isopentenyl polyoxyethylene ether and 0.1 mol maleic anhydride, add 2.5 wt% of 4-dimethylaminopyridine as the polyether macromonomer under nitrogen protection, heat to 85 °C, stir and react for 6 h, dissolve the product in dichloromethane, wash with water, remove the solvent under reduced pressure to obtain the carboxyl-terminated polyether macromonomer.

[0084] S3. Dissolve 8.5g of carboxyl-terminated polyether macromonomer and 5g of hydroxyl-terminated hyperbranched polyester in 150mL of N,N-dimethylformamide. Under nitrogen protection, add 4wt% p-toluenesulfonic acid of the hydroxyl-terminated hyperbranched polyester, heat to 120℃, and stir for 6h to obtain the hyperbranched macromonomer.

[0085] S4. Mix 10g of hyperbranched macromonomer and 0.7g of aminosulfonic acid, add 50g of urea, heat to 140℃ under nitrogen protection, stir for 5h, cool to room temperature, add ethanol to dissolve, filter, remove solvent from filtrate under reduced pressure to obtain sulfonate grafted hyperbranched macromonomer.

[0086] S5. 4g of graphene oxide was uniformly dispersed in 500mL of water, 1.5g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 1.5g of N-hydroxysuccinimide were added, and the mixture was stirred and activated for 30min. 11g of sulfonate-grafted hyperbranched macromonomer was added, and the mixture was heated to 50℃ and stirred for 3h. The mixture was then filtered, washed, and dried to obtain the primary polyether.

[0087] Test Example 1

[0088] The primary polyethers obtained in Examples 1-3 and Comparative Examples 1-4 were diluted with water to a solid content of 60%, and 300 parts were taken. Then, 3 parts of 30wt% hydrogen peroxide were added to obtain solution A. 28 parts of acrylic acid and 1.5 parts of mercaptopropionic acid were mixed with 50 parts of water to obtain solution B. 0.8 parts of reducing agent E51 were weighed and 60 parts of water were added to obtain solution C. The dropping time of solution B was set to 2 hours and the dropping time of solution C was set to 3 hours. Solutions B and C were added dropwise to solution A. The temperature was naturally raised during the dropping process, and the temperature was maintained for 1 hour after the dropping was completed. The solution was neutralized to pH=6 with 20% liquid alkali to obtain the finished polycarboxylate superplasticizer, and its performance was tested.

[0089] Ordinary Portland cement (P.O42.5) was used in all cases. To compare the dispersibility and dispersion retention properties of the prepared water-reducing agent, the flowability of cement paste was tested according to GB8077-2023 standard. 300g of cement and 87g of water were added, and the mixture was stirred for 4 minutes before the flowability of the cement paste was measured on a flat glass plate. The flowability of the paste was also tested at different times. The results are shown in Table 1.

[0090] Table 1

[0091]

[0092] As can be seen from the table above, the water-reducing agents prepared from the primary polyethers obtained in Examples 1-3 of this invention improve the water-reducing and dispersing effect, enhance their slump retention performance, and improve their anti-mud performance.

[0093] The compressive strength of hardened concrete was determined according to the relevant test methods in GB 8076-2008 standard. The results are shown in Table 2.

[0094] Table 2

[0095]

[0096] As can be seen from the table above, the water-reducing agents prepared from the primary polyethers obtained in Examples 1-3 of this invention can significantly improve the mechanical properties of concrete.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a primary polyether, characterized in that, Includes the following steps: S1. A catalytic esterification reaction of pentaerythritol and 2,2-dimethylolpropionic acid was carried out to obtain a hydroxyl-terminated hyperbranched polyester. S2. The polyether macromonomer is reacted with maleic anhydride to obtain a carboxyl-terminated polyether macromonomer; S3. A hyperbranched macromonomer is prepared by catalytic esterification of a carboxyl-terminated polyether macromonomer and a hydroxyl-terminated hyperbranched polyester. S4. Mix hyperbranched macromonomer and aminosulfonic acid, add urea, heat the reaction under inert gas protection, add ethanol to dissolve, filter, remove solvent from filtrate under reduced pressure to obtain sulfonate grafted hyperbranched macromonomer. S5. Dissolve octadecyl dimethyl benzyl ammonium chloride in water, add sodium montmorillonite, heat and stir to intercalate, and obtain intercalated montmorillonite; S6. Graphene oxide is uniformly dispersed in water, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide are added, the mixture is stirred and activated, sulfonate-grafted hyperbranched macromonomers are added, the mixture is heated and stirred to react, intercalated montmorillonite is added, the mixture is heated and stirred, filtered, washed, and dried to obtain primary polyether.

2. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of pentaerythritol to 2,2-dimethylolpropionic acid is 1:5-8, and a catalyst, p-toluenesulfonic acid, is added. The amount of catalyst added is 3-5 wt% of pentaerythritol. The reaction temperature is 120-140℃, and the reaction time is 4-6 h.

3. The preparation method according to claim 1, characterized in that, In step S2, the molar ratio of the polyether macromonomer to maleic anhydride is 1.5-2.5:1, and a catalyst is added, namely 4-dimethylaminopyridine. The reaction temperature is 80-90℃, and the reaction time is 5-7h. The polyether macromonomer is allyl polyoxyethylene ether, methyl allyl polyoxyethylene ether, or isopentenyl polyoxyethylene ether.

4. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of the terminal carboxyl polyether macromonomer to the terminal hydroxyl hyperbranched polyester is 7-10:5, and a catalyst is added. The catalyst is p-toluenesulfonic acid or concentrated sulfuric acid. The amount of catalyst added is 3-5 wt% of the terminal hydroxyl hyperbranched polyester. The reaction temperature is 110-130℃ and the time is 5-7 h.

5. The preparation method according to claim 1, characterized in that, In step S4, the mass ratio of the hyperbranched macromonomer to aminosulfonic acid is 10:0.5-1, the reaction temperature is 135-145℃, and the reaction time is 4-6h.

6. The preparation method according to claim 1, characterized in that, In step S5, the mass ratio of octadecyl dimethyl benzyl ammonium chloride to sodium montmorillonite is 2-3:10, and the heating and stirring intercalation temperature is 45-55℃ for 1-3 hours.

7. The preparation method according to claim 1, characterized in that, In step S6, the mass ratio of graphene oxide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N-hydroxysuccinimide, sulfonate-grafted hyperbranched macromonomer, and intercalated montmorillonite is 3-5:1-2:1-2:10-12:25-35. The heating and stirring reaction is carried out at a temperature of 45-55°C for 2-4 hours, and the heating and stirring time is 0.5-1.5 hours.

8. A primary polyether prepared by the method according to any one of claims 1-7.

9. The application of the primary polyether as described in claim 8 in the preparation of concrete water-reducing agents.

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