Quaternary ammonium salt cationic surfactant, its preparation method and application in glass water

Abstract

The application discloses a kind of quaternary ammonium salt cationic surfactants and its preparation method and application in defoaming glass water, it is related to surfactant technical field.The quaternary ammonium salt cationic surfactant is prepared by the following method: bis-trimethylsiloxy methyl silane is reacted with 4-vinyl phenyl glycidyl ether to generate intermediate 1;Heptaglycol monomethyl ether is reacted with intermediate 1 to generate intermediate 2;Dodecyl dimethyl tertiary amine is reacted with 3-bromo-2,2-bis(bromomethyl) propionic acid to generate quaternary ammonium salt compound;Intermediate 2 is reacted with quaternary ammonium salt compound to generate surfactant.The surfactant prepared in the application has lower surface tension and contact angle, and shows excellent low-temperature stability and detergency.

Description

Technical Field

[0001] This invention relates to the field of surfactant technology, specifically to a quaternary ammonium salt cationic surfactant, its preparation method, and its application in descaling glass cleaner. Background Technology

[0002] Windshield washer fluid is an indispensable cleaning product in daily car maintenance. It is primarily used to remove dust, oil, insect remains, tree sap, and light limescale from the windshield surface to ensure clear visibility for the driver. Windshield washer fluid typically consists of deionized water, alcohol solvents, surfactants, and a small amount of functional additives, offering multiple functions such as cleaning, antifreeze, antistatic, and anti-corrosion. Surfactants are the key component determining the cleaning effect; their role is to reduce interfacial tension, emulsify oil, prevent redeposition of contaminants on the glass surface, reduce friction between the wipers and the glass, and slow down the aging of the rubber wipers. While existing quaternary ammonium salt cationic surfactants possess excellent bactericidal properties and interfacial adsorption capabilities, they still present numerous challenges in the practical application of glass cleaner products. On one hand, traditional quaternary ammonium salt molecules, due to their simple hydrophobic chain structure and excessively high hydrophilic head charge density, exhibit high critical micelle concentrations in aqueous solutions and insufficient efficiency in reducing surface tension. This makes it difficult to achieve rapid spreading and deep wetting at low dosages, limiting their ability to emulsify and remove heavy scale such as oil films and shellac from glass surfaces. On the other hand, the dissolution behavior of most quaternary ammonium salt surfactants is sensitive to low temperatures, easily leading to precipitation, turbidity, or even gelation in winter or cold regions. This results in poor low-temperature fluidity of the glass cleaner and nozzle clogging, severely restricting the product's environmental adaptability and operational stability.

[0003] Chinese invention patent CN103920415A discloses a novel gemini cationic surfactant and its preparation method. The surfactant prepared by this invention introduces groups at the polar head group to achieve chemical bonding, suppressing the separation force between the original single chain and single head group, increasing the affinity between carbon chains, and achieving the purpose of improving surface activity. This opens up a new avenue for practical application. This surfactant has good water solubility and has lower surface tension and CMC value compared with general single-head surfactants, but its stability at low temperature and its detergency are still insufficient. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a quaternary ammonium salt cationic surfactant, its preparation method, and its application in descaling glass cleaner.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A quaternary ammonium salt cationic surfactant has the following structural formula: .

[0006] A method for preparing a quaternary ammonium salt cationic surfactant includes the following steps: S1: Bistrimethylsiloxymethylsilane reacts with 4-vinylphenyl glycidyl ether in the presence of a metal catalyst to generate intermediate 1. S2: Heptaethylene glycol monomethyl ether reacts with intermediate 1 under the action of an acid catalyst to generate intermediate 2. S3: Dodecyl dimethyl tertiary amine reacts with 3-bromo-2,2-bis(bromomethyl)propionic acid to form a quaternary ammonium salt compound. S4: Intermediate 2 reacts with a quaternary ammonium salt compound under the action of an alkaline catalyst to generate a surfactant.

[0007] In step S1, the molar ratio of the bistrimethylsiloxymethylsilane to 4-vinylphenyl glycidyl ether is 1:(1.02-1.05).

[0008] In step S2, the molar ratio of the heptaethylene glycol monomethyl ether to intermediate 1 is 1:(1.02-1.04).

[0009] In step S3, the molar ratio of dodecyl dimethyl tertiary amine to 3-bromo-2,2-bis(bromomethyl)propionic acid is (3.03-3.05):1.

[0010] In step S4, the molar ratio of intermediate 2 to quaternary ammonium salt compound is 1:(1.05-1.08).

[0011] In step S1, the metal catalyst is a platinum catalyst.

[0012] In step S2, the acid catalyst is boron trifluoride diethyl ether.

[0013] In step S4, the base catalyst is 4-dimethylaminopyridine.

[0014] Application of a quaternary ammonium salt cationic surfactant in descaling glass cleaner.

[0015] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include: The surfactant prepared by this invention has low surface tension and contact angle, and exhibits excellent low-temperature stability and descaling performance. Attached Figure Description

[0016] Figure 1 The proton NMR spectrum of the surfactant prepared in Example 1; Figure 2 The image shows a high-resolution mass spectrum of the surfactant prepared in Example 1. Detailed Implementation

[0017] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0018] Example 1 Preparation of Surfactants S1: Under nitrogen protection, 100 ml of anhydrous toluene, 10 mg of platinum catalyst, and 0.102 mol of 4-vinylphenyl glycidyl ether were added to a reaction flask. The mixture was stirred and heated to 60 °C. Then, 100 ml of a toluene solution containing 0.1 mol of bis(trimethylsiloxymethylsilane) was slowly added dropwise over 30 min. After the addition was complete, the reaction was allowed to proceed for 8 h. The mixture was then rotary evaporated at 70 °C to constant weight. The product was purified by silica gel column chromatography (using a mixed solution of ethyl acetate and petroleum ether as eluent, with a volume ratio of ethyl acetate to petroleum ether of 1:4 → 1:1 gradient elution). The product was then rotary evaporated at 50 °C to constant weight and dried under vacuum at 70 °C for 10 h to obtain intermediate 1. The reaction equation is shown below.

[0019] Its 1H NMR data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 7.02 – 6.74 (m,4H), 4.19 (dd, J = 11.8, 3.2 Hz, 1H), 3.94 (dd, J = 11.8, 3.2 Hz, 1H), 3.47 –3.39 (m, 1H), 3.19 (dd, J = 7.7, 2.9 Hz, HRMS (m / z):399.1768[M+H] + .

[0020] S2: Under ice bath conditions, 200 mL of anhydrous tetrahydrofuran and 0.102 mol of intermediate 1 were added to the reaction flask and stirred until well mixed. Then, 0.2 g of boron trifluoride diethyl ether was added, followed by slow dropwise addition of 200 mL of anhydrous tetrahydrofuran solution containing 0.1 mol of heptaethylene glycol monomethyl ether over 30 min. After the addition was complete, the temperature was raised to 40 °C and the reaction was allowed to proceed for 8 h. The mixture was then cooled to 0 °C, and saturated sodium carbonate solution was slowly added until the pH of the solution reached 7. The mixture was then rotary evaporated at 40 °C to constant weight. 300 mL of dichloromethane was added and stirred to dissolve the solution. The mixture was washed once with 150 mL of saturated sodium chloride solution, dried with 40 g of anhydrous sodium sulfate, filtered, and rotary evaporated at 35 °C to constant weight to obtain intermediate 2. The reaction equation is shown below:

[0021] Its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO- d 6 ) δ 7.04 – 6.77 (m, 4H), 4.17 – 4.11 (m, 1H), 3.95 – 3.82 (m, 5H), 3.74 – 3.40 (m, 28H), 3.38 (s, 3H), 2.65 (tt, J = 8.0, 2.7 Hz, 2H), 0.99 (t, J = 8.2 Hz, 2H), 0.06 (s, 18H), -0.07 (s, 3H); HRMS (m / z):739.3869[M+H] + ; S3: Under nitrogen protection, 400 ml of acetonitrile and 0.303 mol of dodecyl dimethyl tertiary amine were added to a reaction flask and stirred at room temperature for 5 min. Then, 0.1 mol of 3-bromo-2,2-bis(bromomethyl)propionic acid was added, and the mixture was heated to reflux for 24 h. After that, the mixture was rotary evaporated at 60 °C to constant weight. Then, 150 ml of anhydrous methanol was added and stirred to dissolve the solid. The solid was then slowly added to 200 ml of acetone, stirred, and precipitated. The solid was filtered, washed three times with acetone (50 ml of acetone each time), and dried under vacuum at 45 °C for 12 h to obtain the quaternary ammonium salt compound. The reaction equation is shown below:

[0022] Its 1H NMR data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 13.51 (s, 1H), 4.13 (s, 6H), 3.43 (t, J = 7.7 Hz, 6H), 3.29 (s, 18H), 1.72 (tt, J = 7.7, 6.2Hz, 6H), 1.42 – 1.24 (m, 54H), 0.93 – 0.84 (m, 9H); HRMS (m / z): 246.2605[M-3Br] 3+ .

[0023] S4: Under nitrogen protection, 800 ml of anhydrous DMF (N,N-dimethylformamide) and 0.105 mol of quaternary ammonium salt compound were stirred and mixed. 0.11 mol of dicyclohexylcarbodiimide and 0.01 mol of 4-dimethylaminopyridine were added, and the mixture was stirred for 15 min. 0.1 mol of intermediate 2 was added, and the mixture was reacted at 25 °C for 10 h. After filtration, the mixture was rotary evaporated at 70 °C to constant weight. Purification was performed by silica gel column chromatography (using a dichloromethane / methanol mixture containing 0.1% (v / v) trifluoroacetic acid as eluent, eluted in a gradient ratio of 15:1 to 5:1). The mixture was rotary evaporated at 50 °C to constant weight to obtain the surfactant. The reaction equation is shown below:

[0024] Its proton nuclear magnetic resonance spectrum is as follows: Figure 1 As shown, its 1H NMR spectrum data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 7.04 – 6.73 (m, 4H), 4.98 (p, J = 4.9 Hz, 1H), 4.40 (dd, J =12.5, 5.0 Hz, 1H), 4.19 – 3.81 (m, 12H), 3.74 – 3.54 (m, 25H), 3.46 – 3.36(m, 9H), 3.28 (s, 18H), 2.67 (tt, J = 7.9, 2.6 Hz, 2H), 1.73 (tt, J = 7.6,6.3 Hz, 6H), 1.43 – 1.22 (m, 54H), 1.00 (t, J = 7.9 Hz, 2H), 0.94 – 0.84 (m, 9H), 0.06 (s, 18H), -0.06 (s, 3H); its high-resolution mass spectrum is as follows: Figure 2 The mass spectrometry data are as follows: HRMS (m / z): 486.3854 [M-3Br] 3+ .

[0025] Example 2 Preparation of Surfactants S1: Under nitrogen protection, 100 ml of anhydrous toluene, 10 mg of platinum catalyst, and 0.103 mol of 4-vinylphenyl glycidyl ether were added to the reaction flask. The mixture was stirred and mixed, and the temperature was raised to 65 °C. Then, 100 ml of toluene solution containing 0.1 mol of bis(trimethylsiloxymethylsilane) was slowly added dropwise over 30 min. After the addition was complete, the reaction was allowed to proceed for 7.5 h. The mixture was then rotary evaporated at 70 °C to constant weight. The mixture was purified by silica gel column chromatography (using a mixed solution of ethyl acetate and petroleum ether as eluent, with a volume ratio of ethyl acetate to petroleum ether of 1:4 → 1:1 gradient elution). The mixture was then rotary evaporated at 50 °C to constant weight and vacuum dried at 70 °C for 10 h to obtain intermediate 1. S2: Under ice bath conditions, add 200 mL of anhydrous tetrahydrofuran and 0.103 mol of intermediate 1 to the reaction flask, stir and mix well, then add 0.2 g of boron trifluoride ether, and slowly add 200 mL of anhydrous tetrahydrofuran solution containing 0.1 mol of heptaethylene glycol monomethyl ether dropwise over 30 min. After the addition is complete, raise the temperature to 45 °C and react for 7 h; cool to 0 °C, slowly add saturated sodium carbonate solution until the solution pH is 7, rotary evaporate at 40 °C to constant weight, add 300 mL of dichloromethane and stir to dissolve, wash once with 150 mL of saturated sodium chloride solution, add 40 g of anhydrous sodium sulfate to dry, filter, and rotary evaporate at 35 °C to constant weight to obtain intermediate 2; S3: Under nitrogen protection, 400 ml of acetonitrile and 0.304 mol of dodecyl dimethyl tertiary amine were added to the reaction flask and stirred at room temperature for 5 min. Then, 0.1 mol of 3-bromo-2,2-bis(bromomethyl)propionic acid was added, and the mixture was heated to reflux for 23 h. The mixture was then rotary evaporated at 60 °C to constant weight. 150 ml of anhydrous methanol was added and stirred to dissolve the solid. 200 ml of acetone was slowly added, and the mixture was stirred until the solid precipitated. The solid was filtered, washed three times with acetone (50 ml of acetone each time), and dried under vacuum at 45 °C for 12 h to obtain the quaternary ammonium salt compound. S4: Under nitrogen protection, 800 ml of anhydrous DMF and 0.107 mol of quaternary ammonium salt compound were stirred and mixed. 0.11 mol of dicyclohexylcarbodiimide and 0.01 mol of 4-dimethylaminopyridine were added, and the mixture was stirred for 15 min. 0.1 mol of intermediate 2 was added, and the mixture was reacted at 25 °C for 9 h. The mixture was filtered, and the solution was rotary evaporated at 70 °C to constant weight. The solution was purified by silica gel column chromatography (using a dichloromethane / methanol mixture as eluent containing 0.1% (v / v) trifluoroacetic acid, eluted in a gradient ratio of 15:1 to 5:1). The solution was rotary evaporated at 50 °C to constant weight to obtain the surfactant.

[0026] Example 3 Preparation of Surfactants S1: Under nitrogen protection, 100 ml of anhydrous toluene, 10 mg of platinum catalyst, and 0.105 mol of 4-vinylphenyl glycidyl ether were added to the reaction flask. The mixture was stirred and heated to 70 °C. Then, 100 ml of toluene solution containing 0.1 mol of bis(trimethylsiloxymethylsilane) was slowly added dropwise over 30 min. After the addition was complete, the reaction was allowed to proceed for 7 h. The mixture was then rotary evaporated at 70 °C to constant weight. The mixture was purified by silica gel column chromatography (using a mixed solution of ethyl acetate and petroleum ether as eluent, with a volume ratio of ethyl acetate to petroleum ether of 1:4 → 1:1 gradient elution). The mixture was then rotary evaporated at 50 °C to constant weight and vacuum dried at 70 °C for 10 h to obtain intermediate 1. S2: Under ice bath conditions, add 200 mL of anhydrous tetrahydrofuran and 0.104 mol of intermediate 1 to the reaction flask, stir and mix well, then add 0.2 g of boron trifluoride ether, and slowly add 200 mL of anhydrous tetrahydrofuran solution containing 0.1 mol of heptaethylene glycol monomethyl ether dropwise over 30 min. After the addition is complete, raise the temperature to 50 °C and react for 6 h. Cool to 0 °C, slowly add saturated sodium carbonate solution until the solution pH is 7, and rotary evaporate at 40 °C to constant weight. Add 300 mL of dichloromethane and stir to dissolve. Wash once with 150 mL of saturated sodium chloride solution, add 40 g of anhydrous sodium sulfate to dry, filter, and rotary evaporate at 35 °C to constant weight to obtain intermediate 2. S3: Under nitrogen protection, 400 ml of acetonitrile and 0.305 mol of dodecyl dimethyl tertiary amine were added to the reaction flask and stirred at room temperature for 5 min. Then, 0.1 mol of 3-bromo-2,2-bis(bromomethyl)propionic acid was added, and the mixture was heated to reflux for 22 h. The mixture was then rotary evaporated at 60 °C to constant weight. 150 ml of anhydrous methanol was added and stirred to dissolve the solid. 200 ml of acetone was slowly added, and the mixture was stirred until the solid precipitated. The solid was filtered, washed three times with acetone (50 ml of acetone each time), and dried under vacuum at 45 °C for 12 h to obtain the quaternary ammonium salt compound. S4: Under nitrogen protection, 800 ml of anhydrous DMF and 0.108 mol of quaternary ammonium salt compound were stirred and mixed. 0.11 mol of dicyclohexylcarbodiimide and 0.01 mol of 4-dimethylaminopyridine were added, and the mixture was stirred for 15 min. 0.1 mol of intermediate 2 was added, and the mixture was reacted at 25 °C for 8 h. The mixture was filtered, and the solution was rotary evaporated at 70 °C to constant weight. The solution was purified by silica gel column chromatography (using a dichloromethane / methanol mixture as eluent containing 0.1% (v / v) trifluoroacetic acid, and eluted in a gradient ratio of 15:1 to 5:1). The solution was rotary evaporated at 50 °C to constant weight to obtain the surfactant.

[0027] Comparative Example 1: The preparation method of the surfactant is basically the same as that of Example 2, except that the bistrimethylsiloxymethylsilane in step S1 is replaced with an equimolar amount of pentamethyldisiloxane.

[0028] Comparative Example 2: The preparation method of the surfactant is basically the same as that of Example 2, except that the bistrimethylsiloxymethylsilane in step S1 is replaced with an equimolar amount of n-butyldimethylsilane.

[0029] Comparative Example 3: The preparation method of the surfactant is basically the same as that of Example 2, except that 4-vinylphenyl glycidyl ether in step S1 is replaced with an equimolar amount of (R)-2-[(allyloxy)methyl]ethylene oxide.

[0030] Comparative Example 4: The preparation method of the surfactant is basically the same as that of Example 2, except that the heptaethylene glycol monomethyl ether in step S2 is replaced with an equimolar amount of 1-eicosadiol.

[0031] Comparative Example 5: The preparation method of the surfactant is basically the same as that of Example 2, except that the heptaethylene glycol monomethyl ether in step S2 is replaced with an equimolar amount of pentaethylene glycol monomethyl ether.

[0032] Comparative Example 6: The preparation method of the surfactant is basically the same as that of Example 2, except that the dodecyl dimethyl tertiary amine in step S3 is replaced with an equimolar amount of N,N-dimethylhexylamine.

[0033] Comparative Example 7: The preparation method of the surfactant is basically the same as that of Example 2, except that 3-bromo-2,2-bis(bromomethyl)propionic acid in step S3 is replaced with an equimolar amount of 3-bromo-2-bromomethylpropionic acid, and the amount of dodecyl dimethyl tertiary amine is replaced with 0.204 mol.

[0034] The platinum catalyst used in this application was prepared by the following method: Weigh 0.205 g of chloroplatinic acid and add it to 9.88 g of isopropanol. Stir at room temperature for 2 h to fully dissolve the chloroplatinic acid in the isopropanol. The solution turns orange-yellow, and the platinum catalyst is obtained.

[0035] The surfactants prepared in the examples and comparative examples were tested for surface tension, low-temperature stability, wetting properties, and detergency. The test results are shown in Table 1.

[0036] Surface tension test: The surfactants prepared in Examples 1-3 and Comparative Examples 1-7 were prepared into 0.1 wt% aqueous solutions of surfactants. The surface tension at 25°C was determined by the plate method in standard GB / T 22237-2008 "Determination of Surface Tension of Surfactants".

[0037] Low temperature stability test: The surfactants prepared in Examples 1-3 and Comparative Examples 1-7 were prepared into a 30wt% surfactant methanol aqueous solution (methanol to water volume ratio of 7:3), placed in a low temperature constant temperature chamber, and observed whether solids precipitated after being placed at -18℃ for 24 hours.

[0038] Wetting performance test: The surfactants prepared in Examples 1-3 and Comparative Examples 1-7 were prepared into a 0.1 wt% surfactant aqueous solution. 5 μl of surfactant aqueous solution was dropped onto a clean quartz plate, and the contact angle was immediately measured using a contact angle meter. Three points were measured for each plate, and three plates were repeated for each sample. The average value was taken as the final result.

[0039] Application example—Preparation of windshield washer fluid: 100g of anhydrous ethanol, 100g of propylene glycol, 10g of sodium silicate, 30g of surfactant, and 2g of defoamer (dimethyl silicone oil) were added sequentially to 600g of deionized water and stirred at 300rpm for 20min to mix evenly, thus obtaining windshield washer fluid.

[0040] Decontamination performance test: Take a 15cm×15cm glass plate and measure its weight W1. Evenly coat the glass plate with 50g of dirt and bake it at 230℃ for 1 hour, measuring its weight W2. Evenly spray 5g of glass cleaner onto the glass plate and let it stand at room temperature for 2 hours. Then rinse it with a sponge under running hot water at 60℃, dry it in an oven, and measure its weight W3. Calculate the decontamination rate according to the following formula: Decontamination rate = [(W2-W3) / (W2-W1)] × 100%; The aforementioned dirt consists of 50wt% chicken fat, 20wt% soybean oil, 20wt% stearic acid, 5wt% tomato sauce, and 5wt% sucrose.

[0041] Table 1. Surfactant Performance Test Data

[0042] As can be seen from Table 1, the surfactants prepared in Examples 1-3 of this application have low surface tension and contact angle, exhibiting excellent wetting properties, low-temperature stability, and descaling rate.

[0043] The surfactant molecules prepared in Examples 1-3 of this application are composed of siloxane groups, polyether segments, long-chain alkyl groups, quaternary ammonium salt cations, ester groups, and benzene rings, and have a "siloxane-polyether-quaternary ammonium salt" multi-block structure. Among them, the siloxane group has extremely low surface energy and excellent flexibility, which can be oriented at the interface and rapidly reduce the surface tension of the system; the polyether segment has good hydrophilicity and solvation ability, which can form a stable hydration layer in the aqueous phase, thereby improving the wettability of the system and significantly reducing the contact angle; the quaternary ammonium salt cation not only enhances the adsorption capacity of the molecule at the polar interface, but also improves the adsorption, stripping and dispersion of dirt particles through electrostatic interaction. The long-chain alkyl group, as a hydrophobic tail, can reduce the interfacial tension and promote the effective penetration and dissolution of hydrophobic pollutants, thereby improving the decontamination rate; the ester group gives the molecule a certain degree of flexibility and interfacial rearrangement ability, which is conducive to the formation of a dense and stable adsorption film; the benzene ring, as a rigid hydrophobic aromatic structure, can generate strong interactions with organic pollutants such as oil through π–π interaction, enhancing the dissolution and stripping ability of stubborn dirt, and its planar rigid structure is conducive to the dense and orderly adsorption of molecules at the interface, further reducing the interfacial tension and promoting the desorption of dirt. Simultaneously, the benzene ring forms a rigid-flexible hydrophobic structure with long-chain alkyl and siloxane groups, promoting the formation of stable micelles / microemulsions, improving oil encapsulation and dispersion capabilities, and inhibiting redeposition. This, combined with the hydrophilic head group of the quaternary ammonium salt and the polyether segment, significantly enhances overall detergency. Furthermore, the low glass transition temperature of the siloxane groups and the anti-crystallization properties of the polyether chains work synergistically to maintain good fluidity and interfacial activity at low temperatures, thus significantly improving low-temperature stability. In summary, this multifunctional structure achieves a comprehensive improvement in surface tension, contact angle, low-temperature stability, and high-efficiency detergency through the synergistic effect of a low surface energy siloxane backbone, hydrophilic polyether chain, and cationic quaternary ammonium salt.

[0044] In Comparative Example 2, replacing the bis(trimethylsiloxymethylsilane) in S1 with n-butyldimethylsilane changed the hydrophobic segments of the surfactant from a Si-O-Si skeleton to Si-C alkyl segments. This resulted in a less regular and dense molecular arrangement at the interface, reducing hydrophobicity and interfacial activity. Simultaneously, the n-butyl chain is less flexible than the siloxane group, leading to decreased stability of the microemulsion or micelle structure, thus significantly reducing overall detergency and low-temperature stability.

[0045] In Comparative Example 4, replacing the heptaethylene glycol monomethyl ether in S2 with 1-eicosadiol changed the hydrophilic segment in the surfactant molecule from a polyether chain to a long-chain fatty alcohol, resulting in a significant decrease in hydrophilicity and reduced aqueous solubility. Simultaneously, the poor flexibility of long-chain fatty alcohols hinders the formation of a dense adsorption layer at the interface, increasing the contact angle and reducing the stability of the microemulsion or micelle structure, leading to a significant decrease in detergency and low-temperature stability.

[0046] In Comparative Example 6, after replacing the dodecyl dimethyl tertiary amine in step S3 with N,N-dimethylhexylamine, the length of the hydrophobic chain in the molecule is shortened, the hydrophobicity of the molecule and the interfacial adsorption capacity are reduced, making it difficult to form a dense and ordered adsorption layer at the gas-liquid or solid-liquid interface, thereby weakening the destructive effect on the cohesive force of the liquid. At the same time, the shortening of the hydrophobic chain reduces the hydrophobicity of the molecular surface, reduces the interfacial wetting ability, and worsens the droplet spreading, resulting in an increased contact angle, which in turn reduces the overall detergency and emulsification performance.

[0047] In Comparative Example 7, after replacing 3-bromo-2,2-bis(bromomethyl)propionic acid in S3 with 3-bromo-2-bromomethylpropionic acid, the number of hydrophobic chains in the molecule decreased, resulting in a decrease in hydrophobicity. At the same time, the overall molecular volume and the compactness of the multi-block structure decreased, and the stability of the microemulsion or micelle structure decreased, thus significantly reducing the detergency, low-temperature stability and emulsification and dispersion ability.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A quaternary ammonium salt cationic surfactant, characterized in that, It has the following structural formula: 。 2. A method for preparing the quaternary ammonium salt cationic surfactant according to claim 1, characterized in that, Includes the following steps: S1: Bistrimethylsiloxymethylsilane reacts with 4-vinylphenyl glycidyl ether in the presence of a metal catalyst to generate intermediate 1. S2: Heptaethylene glycol monomethyl ether reacts with intermediate 1 under the action of an acid catalyst to generate intermediate 2. S3: Dodecyl dimethyl tertiary amine reacts with 3-bromo-2,2-bis(bromomethyl)propionic acid to form a quaternary ammonium salt compound. S4: Intermediate 2 reacts with a quaternary ammonium salt compound under the action of an alkaline catalyst to generate a surfactant.

3. The method for preparing a quaternary ammonium salt cationic surfactant according to claim 2, characterized in that, In step S1, the molar ratio of the bistrimethylsiloxymethylsilane to 4-vinylphenyl glycidyl ether is 1:(1.02-1.05).

4. The method for preparing a quaternary ammonium salt cationic surfactant according to claim 2, characterized in that, In step S2, the molar ratio of the heptaethylene glycol monomethyl ether to intermediate 1 is 1:(1.02-1.04).

5. The method for preparing a quaternary ammonium salt cationic surfactant according to claim 2, characterized in that, In step S3, the molar ratio of dodecyl dimethyl tertiary amine to 3-bromo-2,2-bis(bromomethyl)propionic acid is (3.03-3.05):

1.

6. The method for preparing a quaternary ammonium salt cationic surfactant according to claim 2, characterized in that, In step S4, the molar ratio of intermediate 2 to quaternary ammonium salt compound is 1:(1.05-1.08).

7. The method for preparing a quaternary ammonium salt cationic surfactant according to claim 2, characterized in that, In step S1, the metal catalyst is a platinum catalyst.

8. The method for preparing a quaternary ammonium salt cationic surfactant according to claim 2, characterized in that, In step S2, the acid catalyst is boron trifluoride diethyl ether.

9. The method for preparing a quaternary ammonium salt cationic surfactant according to claim 2, characterized in that, In step S4, the base catalyst is 4-dimethylaminopyridine.

10. The application of the quaternary ammonium salt cationic surfactant of claim 1 in descaling glass cleaner.

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