Cationic surface active agent containing azobenzene structure as well as preparation method and application of cationic surface active agent
By preparing a visible light-responsive cationic surfactant containing an azobenzene structure, the problem of using demulsifiers in traditional emulsion polymerization processes was solved, the reversible conversion of the emulsion under visible light was achieved, the cost was reduced and the product purity was improved.
Patent Information
- Application Number
- CN202510768953.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-10
- Publication Date
- 2025-09-19
AI Technical Summary
Traditional emulsion polymerization processes require the addition of demulsifiers or flocculants, which leads to high costs and affects product purity, and removing the demulsifier requires a lot of energy.
A visible light-responsive cationic surfactant containing an azobenzene structure is used, quaternary ammonium ions are used as hydrophilic groups and azobenzene molecules are used as hydrophobic groups, and the reversible emulsification and demulsification process of the emulsion is achieved by visible light irradiation.
The reversible conversion of the emulsion is achieved under visible light irradiation, avoiding the use of demulsifiers in traditional methods, reducing costs and improving product purity.
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Figure CN120664986A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of surfactant applications, and in particular relates to a cationic surfactant containing an azobenzene structure, a preparation method thereof, and applications thereof. Background Art
[0002] In traditional emulsion polymerization processes, the production of latex particles often requires the addition of demulsifiers or flocculants. However, demulsifiers are expensive and costly to use. Furthermore, their addition can affect product purity, limiting their application. Improving product purity often requires significant energy consumption to remove the added demulsifiers, significantly increasing industrial production costs. Therefore, there is an urgent need to address the cumbersome demulsification process in traditional emulsion polymerization processes. Summary of the Invention
[0003] The purpose of the present invention is to solve the deficiency that a demulsifier or flocculant needs to be added in a traditional emulsion polymerization production process. Starting from an emulsifier, a visible light responsive surfactant containing an azobenzene structure and a preparation method thereof are provided.
[0004] To achieve the above object, the present invention adopts the following technical solutions: A surfactant containing an azobenzene structure, which uses quaternary ammonium ions as hydrophilic groups and azobenzene molecules as hydrophobic groups. Its specific structural formula is as follows: .
[0005] [DFTPDE]Br is preferred.
[0006] The preparation method of the surfactant containing an azobenzene structure comprises the following steps: (1) In an ice bath, add sodium nitrite aqueous solution dropwise to 4-aminodiphenyl ether and hydrochloric acid, stir and react for 2-4 hours, then add deionized water containing fluorinated phenol or phenol, sodium hydroxide and sodium bicarbonate, stir and react in an ice bath for 6-12 hours, filter and wash with deionized water to obtain 4-phenoxyazo fluorinated phenol or 4-phenoxyazophenol; (2) 4-phenoxyazo fluorinated phenol or 4-phenoxyazophenol obtained in step (1), dibromoethane, anhydrous potassium carbonate and N,N-dimethylformamide are mixed at 100-150 o C, stirring and reflux for 12-18 h, cooling, extraction, and purification by chromatography to obtain 4-phenoxyazo fluorinated phenethyl ether bromide or 4-phenoxyazo phenethyl ether bromide; (3) 4-phenoxyazo fluorinated phenethyl ether bromide or 4-phenoxyazo phenethyl ether bromide, trimethylamine and ethanol obtained in step (2) are reacted at 15-45 oC, stirred for 24-36 h, filtered and washed with anhydrous ether to obtain a cationic surfactant containing an azobenzene structure.
[0007] Furthermore, in step (1), the molar ratio of 4-aminodiphenyl ether, hydrochloric acid, sodium nitrite and fluorinated phenol or phenol is 1:(8-10):(3-5):(1-3), wherein 3,5-difluorophenol is the preferred fluorinated phenol; and the molar ratio of fluorinated phenol or phenol, sodium hydroxide and sodium bicarbonate is 1:(2-4):(3-5).
[0008] Furthermore, in step (2), the molar ratio of 4-phenoxyazo fluorinated phenol or 4-phenoxyazophenol, dibromoethane and anhydrous potassium carbonate is 2:(5-7):(3-4).
[0009] Furthermore, in step (3), the molar ratio of 4-phenoxyazo fluorinated phenethyl ether bromide or 4-phenoxyazo phenethyl ether bromide and trimethylamine is 1:(4-6).
[0010] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The fluorinated azobenzene surfactant prepared by the present invention can undergo reversible conversion between cis and trans isomers under the irradiation of visible light, which solves the defect that traditional azobenzene surfactants need ultraviolet light irradiation to convert from trans isomer to cis isomer.
[0011] (2) The fluorinated azobenzene surfactant prepared by the present invention can make the emulsion reversibly switch between emulsification and demulsification under the irradiation of visible light of different wavelengths (405nm, 525nm), which is expected to solve the defect of the traditional emulsion polymerization industry that requires the addition of demulsifiers. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of 4-phenoxyazodifluorophenol.
[0013] Figure 2 This is the H NMR spectrum of 4-phenoxyazodifluorophenethyl bromide.
[0014] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the surfactant containing azobenzene groups obtained in Example 1.
[0015] Figure 4 This is the Fourier infrared spectrum of the azobenzene group-containing surfactant obtained in Example 1.
[0016] Figure 5 This is a graph showing the surface tension change of the azobenzene group-containing surfactant obtained in Example 1.
[0017] Figure 6This is a diagram showing the light response ability of the surfactant containing azobenzene groups obtained in Example 1.
[0018] Figure 7 This is the particle size distribution diagram of polystyrene obtained in Application Example 1.
[0019] Figure 8 Schematic diagram of the reaction route of the azobenzene surfactant [DFTPDE]Br of the present invention. DETAILED DESCRIPTION
[0020] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.
[0021] Example 1 (1) 1.85 g of 4-aminodiphenyl ether (0.01 mol) and 16 mL of dilute hydrochloric acid (18% wt) were added to a flask in sequence. 2.07 g of sodium nitrite (0.03 mol) was dissolved in 15 mL of deionized water and slowly added dropwise to the flask in an ice-water bath. The mixture was stirred for 4 h. The mixture was added to deionized water containing 1.3 g of 3,5-difluorophenol (0.01 mol), 0.8 g of sodium hydroxide (0.02 mol) and 2.52 g of sodium bicarbonate (0.03 mol). The mixture was stirred for 6 h in an ice-water bath. The mixture was filtered and washed with deionized water to obtain 4-phenoxyazodifluorophenol. (2) 1.63 g of 4-phenoxyazodifluorophenol (0.005 mol) obtained in step (1), 2.35 g of dibromoethane (0.0125 mol) and 1.035 g of anhydrous potassium carbonate (0.0075 mol) were added to the flask in sequence, and 15 mL of N,N-dimethylformamide was added as solvent. o C was stirred and refluxed for 18 h, cooled to room temperature and extracted with dichloromethane, and finally purified by chromatography (dichloromethane: petroleum ether = 3:1) to obtain 4-phenoxyazodifluorophenethyl bromide; (3) 2.165 g of 4-phenoxyazodifluorophenyl ether bromide (0.005 mol) obtained in step (2) and 4 g of trimethylamine ethanol solution (30% wt) were added to the flask in sequence, and 10 mL of anhydrous ethanol was added as solvent. o C and stirred for 30 h, filtered and washed with anhydrous ether to obtain a cationic surfactant containing an azobenzene structure.
[0022] The H NMR spectrum of the obtained 4-phenoxyazodifluorophenol is shown in Figure 1 .
[0023] 1H NMR (600 MHz, DMSO- d 6): δ 11.15 (s, 1H), 7.82 (d, J = 8.9 Hz, 2H),7.47 (dd, J = 8.6, 7.4 Hz, 2H), 7.27 – 7.21 (m, 1H), 7.16 – 7.12 (m, 4H), 6.66(d, J = 11.4 Hz, 2H).
[0024] The H NMR spectrum of the obtained 4-phenoxyazodifluorophenethyl ether bromide is shown in Figure 2 .
[0025] 1 H NMR (600 MHz, DMSO- d 6): δ 7.86 (d, J = 8.9 Hz, 2H), 7.47 (dd, J = 8.6,7.4 Hz, 2H), 7.27 – 7.23 (m, 1H),7.15 (dd, J = 8.2, 5.2 Hz, 4H), 7.02 (d, J =11.2 Hz, 2H), 4.50 – 4.46 (m, 2H), 3.86 – 3.82 (m, 2H).
[0026] The H NMR spectrum of the obtained azobenzene cationic surfactant is shown in Figure 3 .
[0027] 1 H NMR (600 MHz, Acetonitrile- d 3): δ 7.85 (d, J = 8.8 Hz, 2H), 7.49-7.44(m, 2H), 7.25 (td, J = 7.5, 1.4 Hz, 1H), 7.17-7.11 (m, 4H), 6.39 (dd, J = 13.4,2.6 Hz, 2H), 4.51 (d, J = 5.1 Hz, 2H), 3.83-3.78 (m, 2H), 3.24 (s, 9H).
[0028] The infrared spectrum of azobenzene cationic surfactant is shown in Figure 4As can be seen from the figure, 1580cm -1 The nearby peak is the stretching vibration peak of N=N, 1487 cm -1 For CN + Stretching vibration peak, 1239 cm -1 is the stretching vibration peak of Ar-O, 1150 cm -1 The nearby peak is the COC asymmetric stretching vibration peak.
[0029] The surface tension change diagram of azobenzene cationic surfactant is shown in Figure 5 , the critical micelle concentration is 3.72×10 - 5 mol / L, and the critical surface tension is 30.5 mN / m.
[0030] The photoresponsiveness of azobenzene cationic surfactants is shown in Figure 6 , it can completely convert from trans structure to cis structure after 7 s of 405 nm light irradiation, indicating that it has excellent light response speed.
[0031] Example 2 (1) 1.85 g of 4-aminodiphenyl ether (0.01 mol) and 17 mL of dilute hydrochloric acid (18% wt) were added to a flask in sequence. 2.415 mL of sodium nitrite (0.035 mol) was dissolved in 15 mL of deionized water and slowly added dropwise to the flask in an ice-water bath. The mixture was stirred for 3.5 h. The mixture was added to deionized water containing 1.3 g of 3,5-difluorophenol (0.01 mol), 1 g of sodium hydroxide (0.025 mol) and 2.52 g of sodium bicarbonate (0.03 mol). The mixture was stirred for 8 h in an ice-water bath. The mixture was filtered and washed with deionized water to obtain 4-phenoxyazodifluorophenol. (2) 1.63 g of 4-phenoxyazodifluorophenol (0.005 mol) obtained in step (1), 2.585 g of dibromoethane (0.0137 mol) and 1.035 g of anhydrous potassium carbonate (0.0075 mol) were added to the flask in sequence, and 15 mL of N,N-dimethylformamide was added as solvent. o C was stirred and refluxed for 16 h, cooled to room temperature and extracted with dichloromethane, and finally purified by chromatography (dichloromethane: petroleum ether = 2:1) to obtain 4-phenoxyazodifluorophenethyl bromide; (3) 2.165 g of 4-phenoxyazodifluorophenyl ether bromide (0.005 mol) obtained in step (2) and 4.5 g of trimethylamine ethanol solution (30% wt) were added to the flask in sequence, and 10 mL of anhydrous ethanol was added as solvent. oC and stirred for 28 h, filtered and washed with anhydrous ether to obtain a cationic surfactant containing an azobenzene structure.
[0032] Example 3 (1) 1.85 g of 4-aminodiphenyl ether (0.01 mol) and 18 mL of dilute hydrochloric acid (18% wt) were added to a flask in sequence. 2.415 mL of sodium nitrite (0.035 mol) was dissolved in 15 mL of deionized water and slowly added dropwise to the flask in an ice-water bath. The mixture was stirred for 3 h. The mixture was added to deionized water containing 1.95 g of 3,5-difluorophenol (0.015 mol), 1.5 g of sodium hydroxide (0.0375 mol) and 3.78 g of sodium bicarbonate (0.045 mol). The mixture was stirred for 10 h in an ice-water bath. The mixture was filtered and washed with deionized water to obtain 4-phenoxyazodifluorophenol. (2) 1.63 g of 4-phenoxyazodifluorophenol (0.005 mol) obtained in step (1), 2.82 g of dibromoethane (0.015 mol) and 1.2 g of anhydrous potassium carbonate (0.00875 mol) were added to the flask in sequence, and 10 mL of N,N-dimethylformamide was added as solvent. o C was stirred and refluxed for 14 h, cooled to room temperature and extracted with dichloromethane, and finally purified by chromatography (dichloromethane: petroleum ether = 1:1) to obtain 4-phenoxyazodifluorophenethyl bromide; (3) 4.33 g of 4-phenoxyazodifluorophenyl ether bromide (0.01 mol) obtained in step (2) and 9.6 g of trimethylamine ethanol solution (30% wt) were added to the flask in sequence, and 15 mL of ethanol was added as solvent. o The reaction was stirred at C for 26 h, filtered and washed with anhydrous ether to obtain a cationic surfactant containing an azobenzene structure.
[0033] Example 4 (1) 1.85 g of 4-aminodiphenyl ether (0.01 mol) and 19 mL of dilute hydrochloric acid (18% wt) were added to a flask in sequence. 3.105 g of sodium nitrite (0.045 mol) was dissolved in 15 mL of deionized water and slowly added dropwise to the flask in an ice-water bath. The mixture was stirred for 2 h. The mixture was then added to deionized water containing 1.88 g of phenol (0.02 mol), 2 g of sodium hydroxide (0.05 mol) and 5.04 g of sodium bicarbonate (0.06 mol). The mixture was stirred for 12 h in an ice-water bath. The mixture was filtered and washed with deionized water to obtain 4-phenoxyazophenol. (2) 1.63 g of 4-phenoxyazophenol (0.005 mol) obtained in step (1), 3.29 g of dibromoethane (0.0175 mol) and 1.2 g of anhydrous potassium carbonate (0.00875 mol) were added to the flask in sequence, and 10 mL of N,N-dimethylformamide was added as solvent. o C was stirred and refluxed for 12 h, cooled to room temperature and extracted with dichloromethane, and finally purified by chromatography (dichloromethane: petroleum ether = 3:1) to obtain 4-phenoxyazophenethyl ether bromide; (3) 4.33 g of 4-phenoxyazophenyl ether bromide (0.01 mol) obtained in step (2) and 8 g of trimethylamine ethanol solution (30% wt) were added to the flask in sequence, and 15 mL of anhydrous ethanol was added as solvent. o C and stirred for 24 h, filtered and washed with anhydrous ether to obtain a cationic surfactant containing an azobenzene structure.
[0034] Application Example 1 In a 150 mL single-necked flask with a magnet, add 0.1 g of the azobenzene surfactant obtained in Example 1, 10 g of styrene from which the polymerization inhibitor had been removed, and 40 mL of deionized water. In a 50 mL beaker, add 0.15 g of initiator (azobisisobutyronitrile) and 10 mL of deionized water, stir thoroughly to dissolve, then add to the single-necked flask and heat at 70 o The reaction was stirred at 400 °C for 12 h. After the reaction was completed, the emulsion was irradiated at a wavelength of 405 nm for 6 h, and then filtered after complete separation to obtain polystyrene.
[0035] The polystyrene particle size distribution obtained in this application example is shown in Figure 7 .
[0036] Application Example 2 In a 150 mL single-necked flask with a magnetic element, add 0.1 g of the nitrophenyl surfactant obtained in Example 1, 10 g of methyl methacrylate (from which the polymerization inhibitor had been removed), and 40 mL of deionized water. In a 50 mL beaker, add 0.15 g of initiator (potassium persulfate) and 10 mL of deionized water, stir thoroughly to dissolve, then add to the above single-necked flask and heat at 70 o The reaction was stirred at 400 °C for 12 h. After the reaction was completed, the emulsion was irradiated at a wavelength of 405 nm for 6 h, and then filtered after complete separation to obtain polymethyl methacrylate.
[0037] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art may still modify or make equivalent substitutions for the specific implementation schemes of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention.
Claims
1. A cationic surfactant containing an azobenzene structure, characterized in that: Its structural formula is as follows: 。 2. A method for preparing a cationic surfactant as claimed in claim 1, characterized in that: The following steps are involved: (1) In an ice bath, sodium nitrite aqueous solution is added dropwise to 4-aminodiphenyl ether and hydrochloric acid, and the mixture is stirred for 2-4 hours. Then, deionized water containing fluorinated phenol or phenol, sodium hydroxide and sodium bicarbonate is added, and the mixture is stirred for 6-12 hours in an ice bath. The mixture is filtered and washed with deionized water to obtain 4-phenoxyazo fluorinated phenol or 4-phenoxyazophenol. (2) 4-phenoxyazo fluorinated phenol or 4-phenoxyazophenol obtained in step (1), dibromoethane, anhydrous potassium carbonate and reaction solvent are mixed at 100-150 o C, stirring and reflux for 12-18 h, cooling, extraction, and purification by chromatography to obtain 4-phenoxyazo fluorinated phenethyl ether bromide or 4-phenoxyazo phenethyl ether bromide; (3) Mix the 4-phenoxyazo fluorinated phenethyl ether bromide or 4-phenoxyazo phenethyl ether bromide, trimethylamine and ethanol obtained in step (2) and heat at 15-45 o The reaction was stirred at C for 24-36 h, filtered and washed with anhydrous ether to obtain a cationic surfactant containing an azobenzene structure.
3. The preparation method according to claim 2, wherein: The fluorinated phenol in step (1) is 3,5-difluorophenol.
4. The preparation method according to claim 2, wherein: The molar ratio of 4-aminodiphenyl ether, hydrochloric acid, sodium nitrite and fluorinated phenol or phenol in step (1) is 1: (8-10): (3-5): (1-3).
5. The preparation method according to claim 2, wherein: The molar ratio of the fluorinated phenol or phenol, sodium hydroxide and sodium bicarbonate in step (1) is 1:(2-4):(3-5).
6. The preparation method according to claim 2, wherein: In step (2), the molar ratio of 4-phenoxyazo fluorinated phenol or 4-phenoxyazophenol, dibromoethane and anhydrous potassium carbonate is 2:(5-7):(3-4); and the reaction solvent is one of N,N-dimethylformamide, N,N-dimethylacetamide and acetonitrile.
7. The preparation method according to claim 2, characterized in that: The molar ratio of 4-phenoxyazo fluorinated phenethyl ether bromide or 4-phenoxyazo phenethyl ether bromide and trimethylamine in step (3) is 1:(4-6).
8. Use of the cationic surfactant containing an azobenzene structure in emulsion polymerization according to claim 1, characterized in that: The cationic surfactant realizes the conversion of cis-trans isomers under irradiation with visible light.