Modified polyether surfactant and application thereof in pesticide

Abstract

The invention discloses a modified polyether surfactant and application thereof in pesticides, and belongs to the technical field of surfactant preparation. A core-shell structure with double-group agglomerated silsesquioxane as a core, amino-terminated zirconium metal organic framework powder as a shell and a polyether chain segment as a middle connecting layer of a flexible chain segment is formed; when the POSS is applied to a pesticide, surface tension can be remarkably reduced, a shell layer of the amino-terminated zirconium metal organic framework powder and a nanoscale concave-convex structure of a leaf wax layer generate a mechanical interlocking effect, and meanwhile, the shell layer of the amino-terminated zirconium metal organic framework powder can physically block direct contact between an organic silicon chain segment of POSS and the environment; the decomposition of cuticles and wax layers of leaf epidermis cells caused by strong permeability is avoided; the shell layer of the amino-terminated zirconium metal organic framework powder and the nanoscale concave-convex structure of the wax layer of the blade generate a mechanical interlocking effect, and meanwhile, the rigid framework of the POSS core resists the rainwater shear force, the liquid drop adhesive force is increased, and the rainwater washing resistance is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of surfactant preparation, in particular to a modified polyether surfactant and application thereof in pesticides. Background Art

[0002] Traditional emulsifiers and dispersants are mostly nonionic surfactants such as alkylphenol polyoxyethylene ethers, alkylphenol polyoxyalkyl ethers, arylphenol polyoxyethylene ethers, and arylphenol polyoxyalkyl ethers, combined with anionic surfactants such as long-chain alkyl benzene sulfonates with 6-22 carbon atoms, sulfosuccinate diesters, sulfates, phosphates, and polycarboxylates. Among these, nonionic surfactants such as alkylphenol polyoxyethylene ethers and alkylphenol polyoxyalkyl ethers are highly toxic to aquatic organisms and have slow biodegradation. In 2003, the European Union issued Directive 2003 / 53 / EC, which prohibits the use of alkylphenol ethoxylates above a limit of 0.1%.

[0003] Silicone agricultural adjuvants are known for their excellent wettability, low surface tension, and super-ductility. For example, the method for preparing a polyether-grafted trisiloxane surfactant, as announced in Announcement No. CN105669968B, produces a polyether-grafted trisiloxane surfactant. This method, when mixed with pesticides, can reduce the amount of pesticide and water used, enhance the pesticide's control effect, conserve water resources, and protect the environment. However, silicones can decompose the cuticle and wax layer of leaf epidermal cells, resulting in a decrease in the plant's water retention capacity. This is especially true for crops with thin wax layers (such as cucumbers, beans, and eggplants), which can easily cause leaves to lose their green color, dry out, wilt, and even fall off. Summary of the Invention

[0004] The present invention aims to provide a modified polyether surfactant and its application in pesticides. By forming a core-shell structure with a diradical polysilsesquioxane as a core, an amino-terminated zirconium metal organic framework powder as a shell, and a polyether segment as an intermediate connecting layer of a flexible segment, the modified polyether surfactant can be applied to pesticides to significantly reduce surface tension. The shell layer of the amino-terminated zirconium metal organic framework powder and the nano-scale concave-convex structure of the wax layer of leaves produce a mechanical interlocking effect. At the same time, the shell layer of the amino-terminated zirconium metal organic framework powder can physically block direct contact between the organosilicon segments of POSS and the environment, thereby preventing the strong permeability from causing decomposition of the cuticle and wax layer of leaf epidermal cells.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A modified polyether surfactant is prepared by the following steps:

[0007] Step 1: hydrolyze vinyltriethoxysilane and (3-mercaptopropyl)trimethoxysilane into silanols under acidic conditions, and then condense them to obtain diradical polysilsesquioxane.

[0008] Step 2: Allyl polyether undergoes a mercapto-ene click reaction with diradical polysilsesquioxane to obtain vinyl polyether, which is then subjected to a hydrosilylation reaction with (3-glycidylpropoxy)trimethoxysilane under the catalysis of chloroplatinic acid to obtain epoxidized polyether.

[0009] Step 3: The zirconium metal ion is coordinated with the organic ligand 2-aminoterephthalic acid to obtain an amino-terminated zirconium metal organic framework powder, and the amino groups on its surface are used to attack the epoxy groups of the epoxidized polyether to obtain a modified polyether surfactant.

[0010] Furthermore, the specific preparation steps of the digroup polysilsesquioxane are as follows:

[0011] Vinyltriethoxysilane, (3-mercaptopropyl)trimethoxysilane and acetone are added to a reaction kettle, stirred at 40-45°C and 400-500 r / min for 20-30 minutes, and then a 1 mol / L glacial acetic acid solution is added as a catalyst. The reaction is continued for 72-74 hours. The product is placed in a mixed solution of acetone and dichloromethane for recrystallization and filtered. The filter cake is washed with deionized water and anhydrous ethanol for 2-3 times respectively, and vacuum dried at 60-80°C for 1-2 hours to obtain a diradical polysilsesquioxane.

[0012] Furthermore, the usage ratio of vinyltriethoxysilane, (3-mercaptopropyl)trimethoxysilane, acetone and glacial acetic acid solution is 30-40 g: 40-50 g: 800-900 mL: 1-2 mL.

[0013] Furthermore, the specific preparation steps of vinyl polyether are as follows:

[0014] Allyl polyether, digroup polysilsesquioxane and tetrahydrofuran are added into a reaction kettle, stirred at 20-25°C and 400-500 r / min for 20-30 minutes, and then a photoinitiator 2,2-dimethylol propionic acid is added. The reaction is cured for 6-7 hours under the conditions of ultraviolet light wavelength of 365-380 nm and light intensity of 6-7 mW / cm. Under ultraviolet light irradiation, the double bond in the allyl polyether and the thiol group of the digroup polysilsesquioxane undergo a thiol-ene click reaction. The reaction is filtered, and the filter cake is washed with deionized water and anhydrous ethanol for 2-3 times respectively, and vacuum dried at 60-80°C for 1-2 hours to obtain vinyl polyether.

[0015] Furthermore, the usage ratio of allyl polyether, diradical polysilsesquioxane, tetrahydrofuran and 2,2-dimethylolpropionic acid is 50-60 mL: 30-40 g: 2-3 L: 1-2 g.

[0016] Furthermore, the specific preparation steps of epoxidized polyether are as follows:

[0017] Add vinyl polyether and 0.05 mol / L chloroplatinic acid-ethanol solution into the reactor, stir for 20-30 min under nitrogen protection, 70-80 ° C and 400-500 r / min, then add (3-glycidylpropoxy)trimethoxysilane, continue stirring and react for 12-14 h, cool naturally to room temperature, and distill under reduced pressure to obtain epoxidized polyether.

[0018] Furthermore, the usage ratio of vinyl polyether, chloroplatinic acid-ethanol solution and (3-mercaptopropyl)trimethoxysilane is 30-40 mL: 500-600 mL: 12-14 g.

[0019] Furthermore, the specific preparation steps of amino-terminated zirconium metal organic framework powder are as follows:

[0020] Zirconium chloride, N,N-dimethylformamide and a 1 mol / L glacial acetic acid solution are added to a polytetrafluoroethylene reactor, stirred at 40-45°C and 400-500 r / min for 20-30 minutes, and ultrasonically dispersed for 40-60 minutes. Then, 2-aminoterephthalic acid is added, ultrasonically dispersed for 40-60 minutes, and kept at 120-130°C for 24-26 hours. The mixture is naturally cooled to room temperature and centrifuged at 2000-3000 r / min for 3-4 minutes. The precipitate is washed with N,N-dimethylformamide 2-3 times, then washed with dichloromethane by centrifugation 2-3 times, and vacuum dried at 60-80°C for 1-2 hours to obtain an amino-terminated zirconium metal organic framework powder.

[0021] Furthermore, the specific method of centrifugal washing is: dispersing the precipitate in dichloromethane, stirring at 20-25°C and 400-500 r / min for 2-3 days, centrifuging at 2000-3000 r / min for 3-4 minutes, filtering, and washing the filter cake with dichloromethane 2-3 times.

[0022] Furthermore, the usage ratio of zirconium chloride, N,N-dimethylformamide, glacial acetic acid solution and 2-aminoterephthalic acid is 12-14 g: 300-400 mL: 1-2 mL: 20-30 g.

[0023] Furthermore, the specific preparation steps of the modified polyether surfactant are as follows:

[0024] Epoxidized polyether, amino-terminated zirconium metal organic framework powder and N,N-dimethylformamide are added to a reactor, stirred at 20-25°C and 400-500 r / min for 20-30 minutes, and then benzyltriethylammonium chloride as a catalyst is added. The mixture is heated to 115-120°C, the reaction is continued for 2-3 hours, and the mixture is naturally cooled to room temperature and distilled under reduced pressure to obtain a modified polyether surfactant.

[0025] Furthermore, the usage ratio of the epoxidized polyether, the amino-terminated zirconium metal organic framework powder, N,N-dimethylformamide and benzyltriethylammonium chloride is 30-40 g: 35-40 g: 1-2 L: 3-4 mL.

[0026] The present invention also provides an application of the modified polyether surfactant in pesticides.

[0027] Beneficial effects of the present invention:

[0028] 1. A modified polyether surfactant prepared by the present invention forms a core-shell structure with a diamino-polysilsesquioxane as a core, an amino-terminated zirconium metal organic framework powder as a shell, and a polyether segment as an intermediate connecting layer of a flexible segment. When applied to pesticides, the modified polyether surfactant can significantly reduce surface tension. The shell layer of the amino-terminated zirconium metal organic framework powder and the nano-scale concave-convex structure of the leaf wax layer produce a mechanical interlocking effect. At the same time, the shell layer of the amino-terminated zirconium metal organic framework powder can physically block direct contact between the organosilicon segments of the POSS and the environment, thereby preventing the strong permeability from causing decomposition of the cuticle and wax layer of the leaf epidermal cells.

[0029] 2. The core-shell structure modified polyether surfactant of the present invention can significantly reduce surface tension, which is far lower than that of traditional hydrocarbon surfactants and unmodified polyether surfactants, achieving rapid spreading in pesticides, forming a uniform drug film on plant leaves, and improving adhesion efficiency. The core-shell structure physically blocks direct contact between the silicone segments of the POSS and the environment through a rigid shell, avoiding strong permeability leading to decomposition of the cuticle and wax layer of leaf epidermal cells, resulting in a decrease in the plant's water retention capacity and stress resistance; the shell layer of the amino-terminated zirconium metal organic framework powder and the nano-scale concave-convex structure of the leaf wax layer produce a mechanical interlocking effect, while the rigid skeleton of the POSS core resists the shear force of rainwater, increases droplet adhesion, and improves rainwater erosion resistance.

[0030] 3. The present invention obtains a cage-shaped POSS structure through silane hydrolysis and condensation. The Si-O-Si cage structure has a rigid inorganic skeleton and low affinity for water. The vinyl groups it carries are non-polar groups, which can reduce surface energy and further improve hydrophobicity. When applied to pesticides, it can significantly reduce surface tension. The rigid inorganic skeleton and amino-terminated zirconium metal organic framework powder have strong adsorption effects, which can increase the sustained release of the pesticide. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Example 1: A modified polyether surfactant is prepared by the following steps:

[0033] S1: 30 g of vinyltriethoxysilane, 40 g of (3-mercaptopropyl)trimethoxysilane and 800 mL of acetone were added to a reactor and stirred at 40°C and 400 r / min for 20 min. Then, 1 mL of 1 mol / L glacial acetic acid solution was added as a catalyst and the reaction was continued for 72 h. The product was recrystallized in a mixed solution of acetone and dichloromethane (volume ratio 1:1) and filtered. The filter cake was washed twice with deionized water and anhydrous ethanol, respectively, and dried in a vacuum at 60°C for 1 h to obtain a dimeric polysilsesquioxane.

[0034] Vinyltriethoxysilane and (3-mercaptopropyl)trimethoxysilane are hydrolyzed into silanols under acidic conditions, and then condensed to obtain a double-group polysilsesquioxane containing vinyl and mercapto groups.

[0035] S2: Add 50 mL of allyl polyether, 30 g of dialkyl polysilsesquioxane and 2 L of tetrahydrofuran into a reactor, stir at 20 ° C and 400 r / min for 20 minutes, then add 1 g of photoinitiator 2,2-dihydroxymethyl propionic acid, and cure for 6 hours under the conditions of ultraviolet light wavelength of 365 nm and light intensity of 6 mW / cm. Under ultraviolet light irradiation, the double bond in the allyl polyether and the thiol group of the dialkyl polysilsesquioxane undergo a thiol-ene click reaction. Filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 60 ° C for 1 hour to obtain vinyl polyether.

[0036] Vinyl polyether is obtained by a thiol-ene click reaction between the double bond in the allyl polyether and the thiol group of the diradical polysilsesquioxane.

[0037] S3: Add 30 mL of vinyl polyether and 500 mL of 0.05 mol / L chloroplatinic acid-ethanol solution into the reactor, stir for 20 min under nitrogen protection, 70 ° C and 400 r / min, then add 12 g of (3-glycidylpropoxy)trimethoxysilane, continue stirring and react for 12 h, cool naturally to room temperature, and distill under reduced pressure to obtain epoxidized polyether.

[0038] Vinyl polyether undergoes a silylation reaction with the silicon-hydrogen bond of (3-glycidylpropoxy)trimethoxysilane under the catalysis of chloroplatinic acid to obtain epoxidized polyether.

[0039] S4: Add 12g of zirconium chloride, 300mL of N,N-dimethylformamide and 1mL of 1mol / L glacial acetic acid solution into a polytetrafluoroethylene reactor, stir at 40°C and 400r / min for 20min, ultrasonically disperse for 40min, then add 20g of 2-aminoterephthalic acid, ultrasonically disperse for 40min, keep warm at 120°C for 24h, cool naturally to room temperature, centrifuge at 2000r / min for 3min, wash the precipitate twice with N,N-dimethylformamide, then centrifuge and wash twice with dichloromethane, and vacuum dry at 60°C for 1h to obtain amino-terminated zirconium metal organic framework powder.

[0040] The specific method of centrifugal washing is as follows: dispersing the precipitate in dichloromethane, stirring at 20°C and 400 r / min for 2 days, centrifuging at 2000 r / min for 3 minutes, filtering, and washing the filter cake twice with dichloromethane.

[0041] 2-Aminoterephthalic acid serves as an organic ligand and coordinates with zirconium metal ions in N,N-dimethylformamide to produce amino-terminated zirconium metal-organic framework powder.

[0042] S5: 30 g of epoxidized polyether, 35 g of amino-terminated zirconium metal organic framework powder and 1 L of N,N-dimethylformamide were added to a reactor, stirred at 20°C and 400 r / min for 20 min, and then 3 mL of benzyltriethylammonium chloride as a catalyst was added. The mixture was heated to 115°C and the reaction was continued for 2 h. The mixture was naturally cooled to room temperature and distilled under reduced pressure to obtain a modified polyether surfactant.

[0043] A modified polyether surfactant is obtained by synthesizing amino-terminated zirconium metal organic framework powder with zirconium as the metal center and using the amino group to attack the epoxy group of epoxidized polyether.

[0044] Example 2: A modified polyether surfactant is prepared by the following steps:

[0045] S1: 35 g of vinyltriethoxysilane, 45 g of (3-mercaptopropyl)trimethoxysilane and 850 mL of acetone were added to a reactor, stirred at 43 ° C and 450 r / min for 25 min, and then 1.2 mL of 1 mol / L glacial acetic acid solution was added as a catalyst. The reaction was continued for 73 h. The product was placed in a mixed solution of acetone and dichloromethane (volume ratio 1:1) for recrystallization and filtered. The filter cake was washed twice with deionized water and anhydrous ethanol, respectively, and dried in a vacuum at 70 ° C for 1.2 h to obtain a digroup polysilsesquioxane.

[0046] S2: Add 55 mL of allyl polyether, 35 g of dialkyl polysilsesquioxane and 2.3 L of tetrahydrofuran into the reactor, stir at 23 ° C and 450 r / min for 25 minutes, then add 1.2 g of photoinitiator 2,2-dihydroxymethyl propionic acid, and cure for 6.5 hours under the conditions of ultraviolet light wavelength of 370 nm and light intensity of 6 mW / cm. Under ultraviolet light irradiation, the double bond in the allyl polyether and the thiol group of the dialkyl polysilsesquioxane undergo a thiol-ene click reaction. Filter, wash the filter cake twice with deionized water and anhydrous ethanol respectively, and dry it in vacuum at 70 ° C for 1.5 hours to obtain vinyl polyether.

[0047] S3: Add 35 mL of vinyl polyether and 550 mL of 0.05 mol / L chloroplatinic acid-ethanol solution into the reactor, stir for 25 min under nitrogen protection, 75 ° C and 450 r / min, then add 13 g of (3-glycidylpropoxy)trimethoxysilane, continue stirring and react for 13 h, cool naturally to room temperature, and distill under reduced pressure to obtain epoxidized polyether.

[0048] S4: 13 g of zirconium chloride, 350 mL of N,N-dimethylformamide and 1.2 mL of 1 mol / L glacial acetic acid solution were added to a polytetrafluoroethylene reactor, stirred at 43°C and 450 r / min for 25 min, and ultrasonically dispersed for 50 min. Then, 25 g of 2-aminoterephthalic acid was added and ultrasonically dispersed for 45 min. The mixture was kept warm at 125°C for 25 h, naturally cooled to room temperature, centrifuged at 2500 r / min for 3.4 min, and the precipitate was washed twice with N,N-dimethylformamide and then washed twice with dichloromethane by centrifugation. It was vacuum dried at 70°C for 1.2 h to obtain amino-terminated zirconium metal organic framework powder.

[0049] The specific method of centrifugal washing is as follows: dispersing the precipitate in dichloromethane, stirring at 23°C and 450 r / min for 2.5 days, centrifuging at 2500 r / min for 3.4 minutes, filtering, and washing the filter cake twice with dichloromethane.

[0050] S5: 35 g of epoxidized polyether, 37.5 g of amino-terminated zirconium metal organic framework powder and 1.5 L of N,N-dimethylformamide were added to a reactor, stirred at 22.5 ° C and 450 r / min for 25 min, and then 3.5 mL of benzyltriethylammonium chloride as a catalyst was added. The mixture was heated to 117.5 ° C and the reaction was continued for 2.5 h. The mixture was naturally cooled to room temperature and distilled under reduced pressure to obtain a modified polyether surfactant.

[0051] Example 3: A modified polyether surfactant is prepared by the following steps:

[0052] S1: Add 40g of vinyltriethoxysilane, 50g of (3-mercaptopropyl)trimethoxysilane and 900mL of acetone into a reactor, stir at 45°C and 500r / min for 30min, then add 2mL of 1mol / L glacial acetic acid solution as a catalyst, continue the reaction for 74h, and recrystallize the product in a mixed solution of acetone and dichloromethane (volume ratio 1:1), filter, and wash the filter cake with deionized water and anhydrous ethanol three times respectively, and dry in a vacuum at 80°C for 2h to obtain a digroup polysilsesquioxane.

[0053] S2: Add 60 mL of allyl polyether, 40 g of dialkyl polysilsesquioxane and 3 L of tetrahydrofuran into the reactor, stir at 25 ° C and 500 r / min for 30 minutes, then add 2 g of photoinitiator 2,2-dihydroxymethyl propionic acid, and cure for 7 hours under the conditions of ultraviolet light wavelength of 380 nm and light intensity of 7 mW / cm. Under ultraviolet light irradiation, the double bond in the allyl polyether and the thiol group of the dialkyl polysilsesquioxane undergo a thiol-ene click reaction. Filter, wash the filter cake with deionized water and anhydrous ethanol three times respectively, and dry it in a vacuum at 80 ° C for 2 hours to obtain vinyl polyether.

[0054] S3: Add 40 mL of vinyl polyether and 600 mL of 0.05 mol / L chloroplatinic acid-ethanol solution into the reactor, stir for 30 min under nitrogen protection, 80 ° C and 500 r / min, then add 14 g of (3-glycidylpropoxy)trimethoxysilane, continue stirring and react for 14 h, cool naturally to room temperature, and distill under reduced pressure to obtain epoxidized polyether.

[0055] S4: Add 14 g of zirconium chloride, 400 mL of N,N-dimethylformamide and 2 mL of 1 mol / L glacial acetic acid solution into a polytetrafluoroethylene reactor, stir at 45°C and 500 r / min for 30 min, ultrasonically disperse for 60 min, then add 30 g of 2-aminoterephthalic acid, ultrasonically disperse for 60 min, keep warm at 130°C for 26 h, cool naturally to room temperature, centrifuge at 3000 r / min for 4 min, wash the precipitate three times with N,N-dimethylformamide, then centrifuge and wash three times with dichloromethane, and vacuum dry at 80°C for 2 h to obtain amino-terminated zirconium metal organic framework powder.

[0056] The specific method of centrifugal washing is as follows: dispersing the precipitate in dichloromethane, stirring at 25°C and 500 r / min for 3 days, centrifuging at 3000 r / min for 4 minutes, filtering, and washing the filter cake with dichloromethane three times.

[0057] S5: 40 g of epoxidized polyether, 40 g of amino-terminated zirconium metal organic framework powder and 2 L of N,N-dimethylformamide were added to a reactor, stirred at 25°C and 500 r / min for 30 min, then 4 mL of benzyltriethylammonium chloride as a catalyst was added, heated to 120°C, and the reaction was continued for 3 h. The mixture was naturally cooled to room temperature and distilled under reduced pressure to obtain a modified polyether surfactant.

[0058] Comparative Example 1: Based on Example 3, without going through step S1, the vinyl polyether in step S3 is replaced by a mixture of vinyltriethoxysilane and (3-mercaptopropyl)trimethoxysilane in a mass ratio of 4:5, and the other steps remain unchanged to obtain a modified polyether surfactant.

[0059] Comparative Example 2: Based on Example 3, step S4 is not performed, the amino-terminated zirconium metal organic framework powder in step S5 is discarded, and the other steps remain unchanged to obtain a modified polyether surfactant.

[0060] Comparative Example 3: Based on Example 3, without going through step S2, the (3-glycidylpropoxy)trimethoxysilane in step S3 is replaced by the (3-mercaptopropyl)trimethoxysilane in step S1, and the other steps remain unchanged to obtain a modified polyether surfactant.

[0061] The modified polyether surfactants obtained in Examples 1-3 and Comparative Examples 1-3 were tested for performance. 1. Surface tension test: The surface tension was measured using a Theta contact angle tensiometer. After the sample was dissolved in distilled water and diluted to a certain concentration, a small amount of the diluted sample was taken with a 10 μL microinjector and tested using the hanging drop method at 25°C. 2. Wettability test: After the sample was dissolved in distilled water and diluted to a certain concentration, a small amount of the diluted sample was taken with a 10 μL microinjector and vertically dropped onto a cucumber leaf laid on a glass slide. The contact angle was measured using a Theta contact angle tensiometer at 25°C. 3. Spreading ability test: 20 uL of a 0.1 wt% modified polyether surfactant aqueous solution and pure water were dropped onto a paraffin sheet using a 50 μL microinjector. The time was recorded with a stopwatch. After 5 minutes, the spread area of ​​the droplet on the paraffin was measured. The experiment was repeated three times and the average value was taken. The results are shown in Table 1. 4. Emulsification Test: Refer to the GB / T1603-2001 standard test, dilute the agrochemical product 200-fold with standard hard water, maintain a constant temperature of 30°C, and let it stand for 1 hour. 5. Suspension Rate Test: Refer to the GB / T14825-2006 standard test, dilute the agrochemical product 200-fold with standard hard water, maintain a constant temperature of 30°C, and let it stand for 1 hour. The results are shown in Table 2.

[0062] Table 1 Performance test table of various modified polyether surfactants

[0063]

[0064] Table 2 Pesticide emulsification and suspension rate test results

[0065] As can be seen from Tables 1 and 2, the surface tension, critical micelle concentration, wettability and spreading ability of the modified polyether surfactants obtained in Examples 1 to 3 are significantly better than those of the comparative example. When used in pesticides, their emulsification and suspension rate are significantly better than those of the comparative example, indicating that the modified polyether surfactants prepared by the present invention can be used in pesticides.

[0066] In Comparative Example 1, the vinyl polyether is replaced by a mixture of vinyltriethoxysilane and (3-mercaptopropyl)trimethoxysilane in a mass ratio of 4:5. A cage-shaped POSS structure is obtained by hydrolysis and condensation of silane. The Si-O-Si cage structure has a rigid inorganic skeleton and has a low affinity for water. The vinyl groups it carries are non-polar groups, which can reduce surface energy and further improve hydrophobicity. When applied to pesticides, it can significantly reduce surface tension, which is much lower than that of traditional hydrocarbon surfactants and unmodified polyether surfactants. It can achieve rapid spreading in pesticides, form a uniform drug film on the plant leaves, and improve adhesion efficiency. The rigid inorganic skeleton and the amino-terminated zirconium metal organic framework powder have a strong adsorption effect, which can increase the sustained release of pesticides.

[0067] In Comparative Example 2, the amino-terminated zirconium metal organic framework powder is discarded, and the polyether segment is grafted onto the surface of the digroup polysilsesquioxane through a thiol-ene click reaction to obtain a vinyl polyether. The vinyl polyether is then subjected to a silylation reaction with the silicon-hydrogen bond of (3-glycidylpropoxy)trimethoxysilane under the catalysis of chloroplatinic acid to obtain an epoxidized polyether. The amino-terminated zirconium metal organic framework powder is uniformly coated on the surface by attacking the epoxy group on the surface of the epoxidized polyether, thereby obtaining a structure with the digroup polysilsesquioxane as the core, the amino-terminated zirconium metal organic framework powder as the shell, and the polyether segment as the intermediate connecting layer of the flexible segment. The core-shell structure physically blocks the direct contact of the organic silicon segment of the POSS with the environment through the rigid shell, thereby avoiding the decomposition of the cuticle and wax layer of the leaf epidermal cells due to strong permeability, resulting in a decrease in the water retention capacity and stress resistance of the plant.

[0068] In Comparative Example 3, (3-glycidyl propoxy)trimethoxysilane is replaced by (3-mercaptopropyl)trimethoxysilane. The silicon-hydrogen bond in (3-mercaptopropyl)trimethoxysilane undergoes a silicon-hydrogen addition reaction with the double bond in the vinyl polyether under the catalysis of chloroplatinic acid to obtain a POSS structure with a sulfhydryl group. The sulfhydryl group cannot chemically bond with the amino-terminated zirconium metal organic framework powder in step S5, and can only partially deposit the amino-terminated zirconium metal organic framework powder on the surface by adsorption. The resulting core-shell structure is unstable, cannot fully exert the sustained-release effect on pesticides, and cannot effectively block the polyether chain segments from directly contacting the leaf surface.

[0069] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A modified polyether surfactant, characterized in that Prepared by the following steps: Step 1: hydrolyzing vinyltriethoxysilane and (3-mercaptopropyl)trimethoxysilane into silanols under acidic conditions, and then condensing them to obtain a diradical polysilsesquioxane; Step 2: A thiol-ene click reaction is carried out between the allyl polyether and the diradical polysilsesquioxane to obtain a vinyl polyether, which is then subjected to a hydrosilylation reaction with (3-glycidylpropoxy)trimethoxysilane under the catalysis of chloroplatinic acid to obtain an epoxidized polyether; Step 3: The zirconium metal ion is coordinated with the organic ligand 2-aminoterephthalic acid to obtain an amino-terminated zirconium metal organic framework powder, and the amino groups on its surface are used to attack the epoxy groups of the epoxidized polyether to obtain a modified polyether surfactant.

2. A modified polyether surfactant according to claim 1, characterized in that, The specific preparation steps of the diradical polysilsesquioxane are as follows: Vinyltriethoxysilane, (3-mercaptopropyl)trimethoxysilane, and acetone are added to a reaction kettle, stirred at 40-45° C. and 400-500 rpm for 20-30 minutes, and then a 1 mol / L glacial acetic acid solution is added as a catalyst. The reaction is continued for 72-74 hours, and the product is recrystallized in a mixed solution of acetone and dichloromethane, filtered, and the filter cake is washed 2-3 times with deionized water and anhydrous ethanol, respectively, and dried in vacuo at 60-80° C. for 1-2 hours to obtain a diradical polysilsesquioxane. The usage ratio of the vinyltriethoxysilane, (3-mercaptopropyl)trimethoxysilane, acetone and glacial acetic acid solution is 30-40 g: 40-50 g: 800-900 mL: 1-2 mL.

3. A modified polyether surfactant according to claim 1, characterized in that, The specific preparation steps of the vinyl polyether are as follows: Allyl polyether, digroup polysilsesquioxane and tetrahydrofuran are added into a reaction kettle, stirred at 20-25°C and 400-500 r / min for 20-30 minutes, and then a photoinitiator 2,2-dimethylol propionic acid is added. The reaction is cured for 6-7 hours under the conditions of ultraviolet light wavelength of 365-380 nm and light intensity of 6-7 mW / cm. Under ultraviolet light irradiation, the double bond in the allyl polyether and the thiol group of the digroup polysilsesquioxane undergo a thiol-ene click reaction. The reaction is filtered, and the filter cake is washed with deionized water and anhydrous ethanol for 2-3 times respectively, and vacuum dried at 60-80°C for 1-2 hours to obtain vinyl polyether.

4. A modified polyether surfactant according to claim 3, characterized in that, The usage ratio of the allyl polyether, the diradical polysilsesquioxane, tetrahydrofuran and 2,2-dimethylolpropionic acid is 50-60 mL: 30-40 g: 2-3 L: 1-2 g.

5. A modified polyether surfactant according to claim 1, characterized in that, The specific preparation steps of the epoxidized polyether are as follows: Add vinyl polyether and 0.05 mol / L chloroplatinic acid-ethanol solution into the reactor, stir for 20-30 min under nitrogen protection, 70-80 ° C and 400-500 r / min, then add (3-glycidylpropoxy)trimethoxysilane, continue stirring and react for 12-14 h, cool naturally to room temperature, and distill under reduced pressure to obtain epoxidized polyether.

6. A modified polyether surfactant according to claim 5, characterized in that, The usage ratio of the vinyl polyether, chloroplatinic acid-ethanol solution and (3-mercaptopropyl)trimethoxysilane is 30-40 mL: 500-600 mL: 12-14 g.

7. A modified polyether surfactant according to claim 1, characterized in that, The specific preparation steps of the amino-terminated zirconium metal organic framework powder are as follows: Zirconium chloride, N,N-dimethylformamide, and a 1 mol / L glacial acetic acid solution are added to a polytetrafluoroethylene reactor, stirred at 40-45°C and 400-500 r / min for 20-30 min, and ultrasonically dispersed for 40-60 min. 2-aminoterephthalic acid is then added, ultrasonically dispersed for 40-60 min, and kept at 120-130°C for 24-26 h. The mixture is naturally cooled to room temperature, centrifuged at 2000-3000 r / min for 3-4 min, and the precipitate is washed 2-3 times with N,N-dimethylformamide, then centrifuged and washed 2-3 times with dichloromethane, and vacuum dried at 60-80°C for 1-2 h to obtain an amino-terminated zirconium metal-organic framework powder. The usage ratio of the zirconium chloride, N,N-dimethylformamide, glacial acetic acid solution and 2-aminoterephthalic acid is 12-14 g: 300-400 mL: 1-2 mL: 20-30 g.

8. A modified polyether surfactant according to claim 7, characterized in that, The specific method of centrifugal washing is as follows: dispersing the precipitate in dichloromethane, stirring at 20-25°C and 400-500 r / min for 2-3 days, centrifuging at 2000-3000 r / min for 3-4 minutes, filtering, and washing the filter cake with dichloromethane 2-3 times.

9. A modified polyether surfactant according to claim 1, characterized in that, The specific preparation steps of the modified polyether surfactant are as follows: Adding epoxidized polyether, amino-terminated zirconium metal organic framework powder and N,N-dimethylformamide into a reaction kettle, stirring at 20-25°C and 400-500 r / min for 20-30 minutes, then adding benzyltriethylammonium chloride as a catalyst, heating to 115-120°C, continuing the reaction for 2-3 hours, naturally cooling to room temperature, and distilling under reduced pressure to obtain a modified polyether surfactant; The usage ratio of the epoxidized polyether, amino-terminated zirconium metal organic framework powder, N,N-dimethylformamide and benzyltriethylammonium chloride is 30-40 g: 35-40 g: 1-2 L: 3-4 mL.

10. Use of a modified polyether surfactant according to any one of claims 1 to 9 in pesticides.

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