A time-delay self-degradation pesticide controlled release agent and a preparation method thereof

Abstract

This invention relates to the field of pesticide formulations and discloses a time-degradable, self-degradable pesticide controlled-release agent and its preparation method. The method includes: firstly mixing TiO2, buffer layer monomer ATA, and tetraethyl orthosilicate under light-protected, alkaline conditions and in the presence of an alcohol solvent to obtain a composite material with a buffer layer coated with TiO2; secondly mixing the TiO2-coated composite material with a template agent in the presence of solvent I to obtain mixture II; thirdly mixing mixture II with tetraethyl orthosilicate and a silane coupling agent under light-protected, alkaline conditions to obtain a nanocarrier; and fourthly mixing the nanocarrier with the active pesticide component under light-protected conditions. The pesticide controlled-release agent prepared by this method can achieve sustained release of pesticides and has time-degradable, self-degradable properties. After the release period, any unreleased pesticide residues can be degraded by the carrier, achieving harmless treatment of pesticide residues without affecting efficacy.

Description

Technical Field

[0001] This invention relates to the field of pesticide formulations, specifically to a time-degradable pesticide controlled-release agent and its preparation method. Background Technology

[0002] In recent years, the rapid development of nanotechnology has provided many solutions for the design and construction of green pesticides. Utilizing the unique properties of nanocarriers to encapsulate pesticide active ingredients offers advantages in reducing pesticide volatilization, decomposition, and loss, lowering application dosage and frequency, and improving utilization and safety. Currently, research on nanopesticide formulations focuses on improving pesticide utilization, duration of effectiveness, and biocompatibility. However, research on the management of residues within the carrier after the protection period ends is relatively limited, and pesticide residue problems remain severe. Studies show that the cumulative release of nanopesticide formulations within one month generally does not exceed 80%. The accumulation of pesticide residues makes them easily translocated to the food chain or seep into groundwater, posing a threat to human and plant / animal survival. Post-treatment of pesticide residues is a complex and expensive task. Therefore, integrating degradation agents into nanopesticides to prepare self-cleaning nanopesticide formulations is a convenient and economical method for reducing pesticide residues.

[0003] Photodegradation using ultraviolet light or sunlight has been widely used to degrade pesticide residues in soil and water. Among various photocatalysts, titanium dioxide nanoparticles are favored due to their mild reaction conditions, simple operation, low cost, and environmental friendliness. Physical blending of titanium dioxide with nano-formulations is a common method for preparing self-cleaning nano-pesticide formulations. Although this method has the advantages of simple preparation and low cost, it also has some drawbacks. First, the photocatalyst and active ingredient are separated by the nanocarrier, making it difficult for titanium dioxide to degrade pesticide residues within the carrier. Furthermore, the exposed photocatalyst may degrade the released pesticide during the release process, reducing the effectiveness of the active ingredient.

[0004] To overcome these shortcomings, there is an urgent need to develop a novel controlled-release pesticide agent that can prevent direct contact between the photocatalyst and the active ingredient during the release period, thus avoiding affecting the efficacy; and after the release period ends, the photocatalyst can directly contact the residual pesticide in the carrier, thereby improving the photocatalytic degradation effect. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of pesticide residues being difficult to degrade and photocatalytic degradation affecting pesticide efficacy in existing pesticide controlled-release agents.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a time-degrading, self-degrading pesticide controlled-release agent, the method comprising:

[0007] (1) Under light-protected conditions, in the presence of alkaline conditions and alcohol solvent, TiO2, buffer layer monomer ATA and tetraethyl orthosilicate were mixed for the first time to obtain a composite material with buffer layer coated with TiO2.

[0008] (2) In the presence of solvent I, the composite material with TiO2 coated by the buffer layer is mixed with the template agent to obtain mixture II;

[0009] (3) Under light-protected and alkaline conditions, the mixture II is mixed with tetraethyl orthosilicate and silane coupling agent for the third time, and then the template agent is removed to obtain the nanocarrier;

[0010] (4) Under light-protected conditions, the nanocarrier is mixed with the active pesticide component in a fourth mixing process to obtain a time-degradable pesticide controlled-release agent;

[0011] Wherein, the buffer layer monomer ATA is the compound shown in formula (I);

[0012]

[0013] A second aspect of the present invention provides a time-degradable pesticide controlled-release agent prepared by the method described in the first aspect.

[0014] The pesticide controlled-release agent prepared by the method provided by this invention can achieve the slow release of pesticides and has the characteristics of delayed self-degradation. The buffer layer monomer ATA can effectively prevent the photocatalyst and active ingredients from contacting each other during the release period. After the release period ends, the unreleased pesticide residues can be degraded by the nanocarrier, achieving the harmless treatment of pesticide residues without affecting the efficacy. Moreover, the start time of the degradation process of the nanocarrier can be artificially controlled to adapt to the actual needs of different active ingredients. Attached Figure Description

[0015] Figure 1 The images show (a) the hydrogen NMR spectrum and (b) the carbon NMR spectrum of substance TK in Preparation Example 1.

[0016] Figure 2 The images show (a) the hydrogen NMR spectrum and (b) the carbon NMR spectrum of substance TK-NHS in Preparation Example 1.

[0017] Figure 3 The images show (a) the hydrogen NMR spectrum and (b) the carbon NMR spectrum of substance ATA in Preparation Example 1.

[0018] Figure 4 The images show the infrared spectra of substances TK, TK-NHS, and ATA from Preparation Example 1.

[0019] Figure 5 This is a schematic diagram of the preparation process of a time-degradable pesticide controlled-release agent.

[0020] Figure 6 The images show the dynamic light scattering (DLS) particle size distribution and scanning electron microscope (SEM) images of TiO2, TiO2-coated composite materials with buffer layers (ATT NP1, ATT NP2, ATT NP3), and the nanocarrier MATT NP1; (a) to (e) show the dynamic light scattering particle size distribution of TiO2, ATT NP1, ATT NP2, ATT NP3, and MATT NP1, respectively; (f) to (j) show the SEM images of TiO2, ATT NP1, ATT NP2, ATT NP3, and MATT NP1, respectively.

[0021] Figure 7 The images are SEM-EDS diagrams of elemental contents (N, S, Ti, Si) in ATT NP1 and MATT NP1 in Example 1. (a) to (f) are SEM-EDS diagrams of elemental contents (N, S, Ti, Si) in the composite material ATT NP1; (g) to (l) are SEM-EDS diagrams of elemental contents (N, S, Ti, Si) in the nanocarrier MATT NP1.

[0022] Figure 8 The figures show (a) nitrogen adsorption-desorption isotherm and (b) thermogravimetric curve of the nanocarrier MATT NP1 prepared in Example 1.

[0023] Figure 9 The graphs show the photocatalytic degradation curves of TiO2-coated composite materials (ATT NP1, ATT NP2, ATT NP3) and their thermogravimetric curves under different conditions.

[0024] Figure 10 This is a graph showing the ·OH generation rates of TiO2, ATT NP1, ATT NP2, and ATT NP3 in the presence of the scavenging agent coumarin.

[0025] Figure 11 These are release curves of active components in pesticide controlled-release agents under different environments.

[0026] Figure 12 This is a bar chart showing the pesticide residue rate under light after the pesticide controlled-release agent has been released.

[0027] Figure 13 These are the results of a pot experiment on controlled-release pesticides. (a) is a picture of the plant growth of *Dendrobium nobile* 20 days after application; (b) is a curve of the efficacy of the controlled-release pesticide; and (c) is a curve of the efficacy of commercially available dicofol. Detailed Implementation

[0028] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0029] As previously described, a first aspect of the present invention provides a method for preparing a time-degrading, self-degrading pesticide controlled-release agent, the method comprising:

[0030] (1) Under light-protected conditions, in the presence of alkaline conditions and alcohol solvent, TiO2, buffer layer monomer ATA and tetraethyl orthosilicate (TEOS) were mixed for the first time to obtain a composite material with buffer layer coated with TiO2.

[0031] (2) In the presence of solvent I, the composite material with TiO2 coated by the buffer layer is mixed with the template agent to obtain mixture II;

[0032] (3) Under light-protected and alkaline conditions, the mixture II is mixed with tetraethyl orthosilicate and silane coupling agent for the third time, and then the template agent is removed to obtain the nanocarrier;

[0033] (4) Under light-protected conditions, the nanocarrier is mixed with the active pesticide component in a fourth mixing process to obtain a time-degradable pesticide controlled-release agent;

[0034] Wherein, the buffer layer monomer ATA is the compound shown in formula (I);

[0035]

[0036] In a preferred embodiment, the thickness of the buffer layer in the TiO2-coated composite material is 10-200 nm. More preferably, the thickness of the buffer layer is 25-125 nm.

[0037] Preferably, the average particle size of the TiO2 is 30-60 nm.

[0038] In a preferred embodiment, the average pore size of the nanocarrier is 1-10 nm.

[0039] Preferably, the average particle size of the nanocarrier is 200-700 nm; the specific surface area of ​​the nanocarrier is 10-50 m². 2 / g.

[0040] In a preferred embodiment, in step (1), the molar ratio of the buffer layer monomer ATA to tetraethyl orthosilicate is 1:0.8-1.2.

[0041] Preferably, in step (1), based on the amount of TiO2 used being 100 mg, the total mass of the buffer layer monomer ATA and tetraethyl orthosilicate is 10-350 mg.

[0042] Preferably, in step (1), the pH value of the alkaline conditions is 9-14.

[0043] In a preferred embodiment, in steps (1) and (3), the alkaline conditions are provided by an alkaline substance; the alkaline substance is selected from at least one of ammonia and sodium hydroxide. Preferably, the alkaline substance is added in the form of an aqueous solution, and the mass concentration of the aqueous solution is 10-30 wt%.

[0044] Preferably, the alcohol solvent is methanol and / or ethanol.

[0045] In a preferred embodiment, in step (1), the amount of alcohol solvent used is 4-6 mL, based on the amount of TiO2 used being 100 mg.

[0046] To obtain a time-degradable pesticide controlled-release agent with higher photocatalytic degradation efficiency, the first mixing is preferably carried out in a manner including the following steps:

[0047] (1-1) The buffer layer monomers ATA and TEOS, along with TiO2, were ultrasonically dispersed in ethanol;

[0048] (1-2) Add the alkaline substance dropwise to the ultrasonically blended material described in step (1-1) and react it in the dark.

[0049] Preferably, the method further includes: sequentially separating, washing, and vacuum drying the product obtained from the first mixing; to obtain the composite material with the buffer layer coated with TiO2.

[0050] Preferably, in step (2), the mass ratio of the TiO2-coated composite material to the template agent in the buffer layer is 1:3-4.

[0051] In a preferred embodiment, the template agent is selected from at least one of hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and octadecyltrimethoxysilane.

[0052] Preferably, in step (2), the amount of solvent I used is 150-200 mL relative to 100 mg of the composite material with TiO2 coated by the buffer layer.

[0053] Preferably, solvent I is water and / or ethanol.

[0054] Preferably, solvent I is a mixed solution of water and ethanol; and the volume ratio of water to ethanol is 1:0.5-1.

[0055] In order to further improve the delayed self-degradation performance of pesticide controlled-release agents, preferably, in step (3), the amount of tetraethyl orthosilicate is 3-5g relative to 100mg of the composite material with TiO2 coated by the buffer layer, and the amount of silane coupling agent is 0.8-1.0g.

[0056] In a preferred embodiment, in step (3), the pH value of the alkaline condition is 9-14.

[0057] In a preferred embodiment, the silane coupling agent is selected from at least one of 3-aminopropyltriethoxysilane (APTES), (3-aminopropyl)dimethylethoxysilane, and aminopropylaminoethyltrimethoxysilane.

[0058] Preferably, the step of removing the template agent includes:

[0059] 5-7g of the dried third mixture was ultrasonically dispersed in 50-70mL hydrochloric acid and 180-200mL anhydrous ethanol for 5-7h. The supernatant was then removed by centrifugation. The lower precipitate after centrifugation was washed three times with distilled water and anhydrous ethanol, and then vacuum dried at 40-60℃ for 20-30h to obtain the nanocarrier. The concentration of the hydrochloric acid was 1-5mol / L.

[0060] Preferably, in step (4), the mass ratio of the nanocarrier to the pesticide active ingredient is 1:0.1-10. More preferably, the mass ratio of the nanocarrier to the pesticide active ingredient is 1:0.5-2. The inventors have found that, under this preferred condition, the obtained pesticide controlled-release agent exhibits better drug loading performance during controlled release.

[0061] In a preferred embodiment, the active pesticide component is added in the form of an aqueous solution, the concentration of which is preferably 1-5 mg / mL.

[0062] The present invention does not particularly limit the type of pesticide active ingredient, which can be a conventional pesticide ingredient in the art, such as dicamba, dichloropyridine acid pesticide, etc.; those skilled in the art can select according to their needs.

[0063] According to a preferred embodiment, the conditions for the first mixing include: a temperature of 55-65°C and a time of 5-7 hours.

[0064] According to another preferred embodiment, the conditions for the second mixing include mixing under ultrasonic conditions for 20-30 minutes.

[0065] Preferably, the conditions for the third mixing include: a temperature of 25-35°C and a time of 5-7 hours.

[0066] Preferably, the conditions for the fourth mixing include: a temperature of 25-35°C and a time of 12-24 hours.

[0067] The first, third, and fourth mixing processes described in this invention are preferably carried out under stirring conditions. This invention does not have any special requirements for the stirring speed, and those skilled in the art can select it as needed.

[0068] The various steps of the preparation method described above may also involve various post-processing operations known in the art, such as extraction, washing, separation, filtration, drying, etc. The present invention does not have any particular limitations in this regard, and those skilled in the art should not understand it as a limitation of the present invention.

[0069] The present invention does not impose any particular limitation on the preparation method of the buffer layer monomer ATA. Those skilled in the art can use known techniques in the art to prepare it. In the following text, the present invention provides an exemplary preparation method of the buffer layer monomer ATA, which should not be construed as a limitation of the present invention.

[0070] Preferably, the method for preparing the buffer layer monomer ATA includes the following steps:

[0071] S1: 3-Mercaptopropionic acid and acetone are first contacted in a hydrogen chloride atmosphere to obtain substance TK;

[0072] S2: In the presence of dichloromethane, the substance TK is subjected to a second contact with N-hydroxysuccinimide and diimide hydrochloric acid to obtain substance TK-NHS;

[0073] S3: In the presence of a protective gas and dichloromethane, the substance TK-NHS is brought into a third contact with the compound shown in formula (II) to obtain the compound shown in formula (I);

[0074]

[0075] Preferably, in step S1, the mass ratio of 3-mercaptopropionic acid to acetone is 1:1.0-1.1.

[0076] In a preferred embodiment, in step S2, the mass ratio of substance TK to N-hydroxysuccinimide and diimide hydrochloric acid is 1:1-1.2:2.2-2.4.

[0077] Preferably, in step S3, the mass ratio of the substance TK-NHS to the compound shown in formula (II) is 1:1.0-1.1.

[0078] Preferably, the protective gas is selected from at least one of nitrogen and argon.

[0079] Preferably, in step S1, the first contact time is 5-7 hours.

[0080] In a preferred embodiment, the second contact time in step S2 is 10-15 hours.

[0081] Preferably, in step S2, the amount of dichloromethane used is 90-110 mL relative to 1.0 g of the substance TK-NHS.

[0082] In a preferred embodiment, the third contact time in step S3 is 10-15 hours.

[0083] Preferably, in step S3, the amount of dichloromethane used is 20-40 mL relative to 1.0 g of the substance TK-NHS.

[0084] It should be noted that in this invention, both acetone and dichloromethane are ultra-dry solvents; that is, the acetone is ultra-dry acetone, and the dichloromethane is ultra-dry dichloromethane. The ultra-dry dichloromethane and ultra-dry acetone can be purchased directly, or they can be obtained by dehydration using experimental methods for obtaining ultra-dry solvents in this field. For example, adding 3A molecular sieve to the solvent to be dried overnight can remove water.

[0085] According to a preferred embodiment, the method further includes: sequentially freezing, washing, and drying the material after the first contact to obtain substance TK.

[0086] In a preferred embodiment, the freezing conditions include a temperature of -30 to 5°C and a time of 6 to 15 hours.

[0087] The present invention does not have any particular requirements for the drying and washing methods, which can be carried out according to methods known in the art. The present invention provides an exemplary method in the following text, which should not be construed as a limitation of the present application by those skilled in the art.

[0088] Preferably, the method further includes: washing the material after the second contact with 0.5-1.5 mol / L hydrochloric acid, then extracting it sequentially with saturated sodium bicarbonate solution and saturated sodium chloride solution, and then drying the extracted organic phase with anhydrous sodium sulfate to obtain the substance TK-NHS.

[0089] The present invention uses the compound shown in formula (I) as a buffer layer material in the pesticide controlled-release agent carrier, which can effectively improve the efficacy and photocatalytic degradation efficiency of the pesticide controlled-release agent.

[0090] The pesticide controlled-release agent preparation method provided by the present invention encapsulates the active pesticide component and photocatalyst in a nanocarrier, and constructs a barrier layer (buffer layer) between the photocatalyst and the active pesticide component that can be gradually degraded by reactive oxygen species. This avoids direct contact between the two during the release of the pesticide, thereby improving the efficiency of photocatalytic degradation without affecting the efficacy of the pesticide.

[0091] As previously described, a second aspect of the present invention provides a time-degradable pesticide controlled-release agent prepared by the method described in the first aspect.

[0092] Preferably, the time-degradable pesticide controlled-release agent contains a photocatalytic degradation core, a timed buffer layer, a drug loading layer, and pesticide active components located on the loading layer.

[0093] Preferably, the photocatalytic degradation core is titanium dioxide; the drug loading layer is mesoporous silicon; and the material of the timing buffer layer is sensitive to reactive oxygen species.

[0094] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials are commercially available products. In the following preparation examples or instances, room temperature means 20±5℃.

[0095] Tetraethyl orthosilicate (TEOS) was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0096] Template agent: hexadecyltrimethylammonium bromide (CTAB) was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0097] 3-Aminopropyltriethoxysilane (APTES) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0098] Titanium dioxide was purchased from Aladdin Reagent Company; it was anatase with an average particle size of 60 nm.

[0099] In the following examples:

[0100] a) Material particle size and morphology determination: Dynamic light scattering particle size analyzer, model Malvern Panalytical, purchased from Malvern Ltd., UK; Scanning electron microscope (SEM), model JSM-6700F, purchased from Hitachi Ltd., Japan.

[0101] b) Elemental analysis: Transmission electron microscope, Tecnai G2 F30, purchased from FEI; Inductively coupled plasma mass spectrometry, Aglient 720ES (OES), purchased from Aglient, USA.

[0102] The test conditions and methods for organic element S are as follows: the sample is completely combusted in a pure oxygen atmosphere at a high temperature of 1150℃ to obtain gas, which is then reduced and separated by adsorption-desorption column separation and separated by chromatographic column for thermal conductivity detection.

[0103] Test methods and conditions for inorganic element Ti: After digesting the sample with acid, the element was quantitatively analyzed by inductively coupled plasma mass spectrometry.

[0104] c) The material specific surface area characterization analysis was carried out using the following test methods and conditions: the sample was placed in a vacuum system and degassed at 100℃ for 4 hours as a pretreatment, and then tested under adsorption conditions of -196℃ and N2.

[0105] d) Thermogravimetric analysis was performed using the following test methods and conditions: Test method: The sample was placed in a crucible and tested under the set parameters, which were: heating rate of 10℃ / min, temperature range of 40-800℃, and oxygen as the carrier gas.

[0106] Preparation Example 1

[0107] This preparation example uses the following synthetic route to prepare the buffer layer monomer ATA.

[0108]

[0109] S1: In a hydrogen chloride atmosphere, 2.50 g of 3-mercaptopropionic acid and 2.74 g of ultra-dry acetone were added to a 200 mL three-necked flask and reacted at room temperature for 6 h to obtain a colorless and transparent liquid. The obtained colorless and transparent liquid was frozen at -20 °C for 12 h, then washed three times with ice-cold hexane solution and ice-cold distilled water, and then dried under vacuum at 25 °C for 12 h to obtain substance TK (white crystals).

[0110] S2: Add 1.0 g TK, 1.1 g N-hydroxysuccinimide, 2.3 g diimide hydrochloric acid and 100 mL ultra-dry dichloromethane to a 250 mL round-bottom flask and stir at room temperature for 12 h. The reaction product is washed with 1 mol / L hydrochloric acid solution and then extracted with saturated sodium bicarbonate solution and saturated sodium chloride solution in sequence. The organic phase is dried with anhydrous sodium sulfate to obtain substance TK-NHS (white solid).

[0111] S3: Under a nitrogen atmosphere, add 3.0 g TK-NHS, 3.18 mL 3-aminopropyltriethoxysilane, and 100 mL ultra-dry dichloromethane to a 100 mL three-necked flask. React at room temperature for 12 h. After the reaction is complete, use a rotary evaporator to evaporate the solvent in the sample to obtain the substance ATA.

[0112] The above-prepared substances TK, TK-NHS, and ATA were characterized by nuclear magnetic resonance (NMR) (using DMSO-d6 as solvent) and infrared spectroscopy. The NMR spectra of substances TK, TK-NHS, and ATA are as follows: Figure 1 , Figure 2 , Figure 3 The infrared spectra of substances TK, TK-NHS, and ATA are shown in Figure 4.

[0113] Example 1

[0114] according to Figure 5 The preparation process shown is used to prepare a time-degradable pesticide controlled-release agent:

[0115] (1-1) The buffer layer monomers ATA and TEOS were ultrasonically dispersed with 120 mg of TiO2 in ethanol for 10 min;

[0116] Based on a TiO2 dosage of 100 mg, the total mass of the buffer layer monomer ATA and tetraethyl orthosilicate is 320 mg, and the amount of ethanol is 6 mL; the molar ratio of the buffer layer monomer ATA to TEOS is 1:1.

[0117] (1-2) 28 wt% ammonia water was added dropwise to the ultrasonically blended material described in step (1-1) to adjust the pH value of the blend to 12.5; the mixture was reacted at 60°C in the dark for 6 h, and then the product was centrifuged, the supernatant was discarded, and the precipitate was washed three times with anhydrous ethanol and distilled water in sequence, and then vacuum dried at 30°C for 12 h to obtain a composite material with a buffer layer coated with TiO2 (named ATTNP1).

[0118] (2) In the presence of 140 mL of distilled water and 104 mL of anhydrous ethanol, 140 mg of TiO2-coated composite material with buffer layer was sonicated with 520 mg of CTAB for 30 min to obtain mixture II.

[0119] (3) Add 28wt% ammonia to mixture II to adjust the pH to 11, then add 5.6g of TEOS and 1.2g of APTES and react at 30℃ in the dark for 6h. After the reaction is complete, centrifuge to remove the supernatant, wash the precipitate three times with distilled water and ethanol, and dry to constant weight.

[0120] 6g of dried product was ultrasonically dispersed in 60mL of 3mol / L hydrochloric acid and 190mL of anhydrous ethanol for 6h. The supernatant was removed by centrifugation. The lower precipitate after centrifugation was washed three times with distilled water and anhydrous ethanol, and then vacuum dried at 50℃ for 24h to obtain the nanocarrier (named MATT NP1).

[0121] (4) Weigh 200 mg of dicamba and 200 mL of distilled water and mix them with ultrasonically in the dark for 2 min to prepare a 1 mg / mL dicamba aqueous solution; disperse 200 mg of MATT NP1 with 200 mL of dicamba aqueous solution (1 mg / mL) with ultrasonically for 5 min and stir at 30 °C in the dark for 24 h; after the reaction is complete, transfer it to an EP tube, centrifuge to remove the supernatant, wash the precipitate after centrifugation with distilled water 3 times, and then place it in a vacuum drying oven and dry at 30 °C for 12 h to obtain a time-degradable pesticide controlled-release agent (named dicamba@MATT NP1).

[0122] Example 2

[0123] This application uses a method similar to that in Example 1 to prepare a time-degradable pesticide controlled-release agent. The difference is that, in step (1-1), based on the amount of TiO2 used being 100 mg, the total mass of the buffer layer monomer ATA and tetraethyl orthosilicate is 160 mg, the amount of ethanol used is 6 mL, and the molar ratio of the buffer layer monomer ATA to tetraethyl orthosilicate is 1:1; a composite material with a buffer layer coated with TiO2 is obtained (named ATT NP2);

[0124] The remaining steps are the same as in Example 1.

[0125] Example 3

[0126] This application uses a method similar to that in Example 1 to prepare a time-degradable pesticide controlled-release agent. The difference is that, in step (1-1), based on the amount of TiO2 being 100 mg, the total mass of the buffer layer monomer ATA and tetraethyl orthosilicate is 16 mg, the amount of ethanol is 6 mL, and the molar ratio of the buffer layer monomer ATA to tetraethyl orthosilicate is 1:1; a composite material with a buffer layer coated with TiO2 is obtained (named ATT NP3);

[0127] The remaining steps are the same as in Example 1.

[0128] Comparative Example 1

[0129] (1) In the presence of 140 mL of anhydrous ethanol, 140 mg TiO2 and 520 mg CTAB were ultrasonically dispersed for 30 min to obtain mixture II;

[0130] (2) Add 28wt% ammonia dropwise to mixture II to adjust the pH to 11, then add 5.6g TEOS, react at 30℃ in the dark for 6h, centrifuge to remove the supernatant after the reaction, wash the precipitate three times with distilled water and ethanol, and dry to constant weight.

[0131] 6g of dried product was ultrasonically dispersed in 60mL of 3mol / L hydrochloric acid and 190mL of anhydrous ethanol for 6h. The supernatant was removed by centrifugation. The lower precipitate after centrifugation was washed three times with distilled water and anhydrous ethanol, and then vacuum dried at 50℃ for 24h to obtain nanocarriers (named MT NPs).

[0132] (3) Weigh 200 mg of dicamba and 200 mL of distilled water and mix them with ultrasonically in the dark for 2 min to prepare a 1 mg / mL dicamba aqueous solution; disperse 200 mg of MT NPs with 200 mL of dicamba aqueous solution (1 mg / mL) with ultrasonically for 5 min and stir at 30 °C in the dark for 24 h; after the reaction is complete, transfer it to an EP tube, centrifuge to remove the supernatant, wash the precipitate after centrifugation with distilled water 3 times, and then place it in a vacuum drying oven and dry at 30 °C for 12 h to obtain a time-degradable pesticide controlled-release agent (named dicamba@MT NPs).

[0133] Comparative Example 2

[0134] (1) Dissolve 1.0 g CTAB and 0.28 g NaOH in 480 mL of distilled water and stir vigorously. Then, slowly add 5.0 g TEOS dropwise to the above solution at 80 °C and stir for 4 h. Centrifuge to obtain a white solid. Wash the precipitate three times with distilled water and methanol in sequence. Dry under vacuum at 45 °C for 12 h to obtain mSiO2 containing CTAB.

[0135] 10g of the dried product was placed in a muffle furnace and calcined at 550℃ for 8h to obtain mSiO2.

[0136] (2) Weigh 200 mg of dicamba and 200 mL of distilled water and mix them with ultrasonically in the dark for 2 min to prepare a 1 mg / mL dicamba aqueous solution; disperse 200 mg of mSiO2 with 200 mL of dicamba aqueous solution (1 mg / mL) with ultrasonically for 5 min and stir at 30 °C in the dark for 24 h; after the reaction is complete, transfer it to an EP tube, centrifuge to remove the supernatant, wash the precipitate after centrifugation with distilled water 3 times, and then place it in a vacuum drying oven and dry it at 30 °C for 12 h to obtain a time-degradable pesticide controlled-release agent (named dicamba@mSiO2).

[0137] Comparative Example 3

[0138] The dicamba@mSiO2 (200 mg) prepared in Comparative Example 2 was shaken and mixed with TiO2 (20 mg) for 30 min to obtain a time-degradable pesticide controlled-release agent (named dicamba@mSiO2+TiO2).

[0139] Test case

[0140] 1. Structural characterization test

[0141] (1) Material particle size determination and morphology observation

[0142] This invention provides, exemplarily, dynamic light scattering (DLS) particle size distribution maps and scanning electron microscope images (e.g., for TiO2, the TiO2-buffered composite materials ATT NP1, ATT NP2, and ATT NP3 in Examples 1-3, and the nanocarrier MATT NP1 in Example 1) of TiO2, the TiO2-buffered composite materials in Examples 1-3, and the nanocarrier MATT NP1 in Example 1. Figure 6 (As shown).

[0143] exist Figure 6 By comparing the particle sizes of TiO2 with ATT NP1, ATT NP2, and ATT NP3, the thickness of the buffer layer in the composite material with TiO2 coated with the buffer layer can be calculated to be 25-125 nm.

[0144] Depend on Figure 6 It can be seen that the particle sizes of ATT NP1, ATT NP2, and ATT NP3 are significantly larger than those of TiO2, indicating that the buffer layer (containing monomers ATA and TEOS) of the nanocarrier has been successfully coated on the TiO2 core. The increasing particle sizes of ATT NP3, ATT NP2, and ATT NP1 in that order imply an increase in the thickness of the ATT layer, suggesting that the thickness of the buffer layer can be easily controlled by changing the amounts of monomers ATA and tetraethyl orthosilicate. After coating with the mesoporous silica drug-supporting layer, the particle size of the nanocarrier further increases to approximately 700 nm, indicating that the drug-supporting layer has been successfully coated on the outer surface of the buffer layer.

[0145] (2) Elemental Analysis

[0146] This invention provides, by way of example, SEM-EDS analysis of the composite materials ATT NP1 and MATT NP1 in Example 1, as follows: Figure 7 As shown. In Figure 7 In the diagram, the purple, yellow, red, and green dots represent the distribution of N, S, Ti, and Si elements, respectively. Figure 7 It can be seen that the carrier contains elements such as Ti, S, N, and Si. Among them, the Ti element comes from the TiO2 core, the S and N elements come from the buffer layer, and the Si element comes from the buffer layer and the drug loading layer. This indicates that we have successfully prepared a self-degradable nanocarrier with a three-layer structure (TiO2 core, timed buffer layer, and drug loading layer).

[0147] (3) Specific surface area and thermogravimetric analysis test

[0148] This invention provides, by way of example, the nitrogen adsorption-desorption isotherm and thermogravimetric curve of the nanocarrier MATT NP1 prepared in Example 1, as shown below. Figure 8 As shown. In Figure 8In the middle, (a) is the nitrogen adsorption-desorption isotherm of the nanocarrier MATT NP1, and (b) is the thermogravimetric curve of the nanocarrier MATT NP1.

[0149] Depend on Figure 8 As can be seen from (a) in the figure, the adsorption curve of the nanocarrier MATT NP1 belongs to type II of IUPAC, with a specific surface area of ​​30.30 m². 2 / g; the presence of capillary aggregation and hysteresis loops indicates that the nanocarrier has a significant mesoporous structure with an average pore size of 3.62 nm.

[0150] Depend on Figure 8 As shown in (b), the nanocarrier MATT NP1 loses approximately 29.1% of its mass at 40-800℃. When the nanocarrier is loaded with the drug dicamba, the mass loss is approximately 50.8%, resulting in a nano-formulation containing approximately 21.7% of the original drug.

[0151] (4) Determination of drug loading efficiency of nanocarriers in pesticide controlled-release agents

[0152] The loading efficiency of the nanocarrier dicamba was determined and analyzed by high performance liquid chromatography (HPLC). The chromatographic conditions were as follows: the column was a 693970-902T InfinityLab Poroshell 120EC-C18 reversed-phase column (4.6×150mm, 4μm), and the mobile phase was V... 乙腈 V 0.1wt％磷酸 = 60:40; flow rate: 1.0 mL / min; injection volume: 40 μL; detection wavelength: 220 nm; column temperature: 30 °C. All samples were filtered using an organic filter membrane with a pore size of 0.22 μm.

[0153] A 1 mg / mL dicamba standard solution was prepared, and a standard curve was established by diluting it at different ratios (0.5 mg / mL, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, 0.05, 0.045, 0.04, 0.035, 0.03, 0.025, 0.02, 0.015, 0.01, 0.005 mg / mL). The concentration of the supernatant was determined using HPLC. The product of the supernatant concentration and the supernatant volume is the mass of dicamba contained in the supernatant. The difference between the total mass of dicamba added and the remaining mass of the supernatant is the loaded mass. The calculation formula is as follows:

[0154] Drug loading rate / % = (total mass of dicamba added - remaining mass of supernatant) / carrier mass × 100%;

[0155] Encapsulation rate / % = (Total mass of dicamba input - Remaining mass of supernatant) / Total mass input × 100%;

[0156] After measurement and analysis, it was calculated that the efficiency of the nanocarrier (MATT NP1) in loading dicamba was approximately 30.1%; the encapsulation efficiency was 30.1%.

[0157] 2. Test on the photocatalytic degradation performance of the composite material with TiO2 buffer layer

[0158] The photocatalytic degradation experiment was carried out in a multi-channel reaction system. The light source was a full-band LED cold light source. The reaction system was equipped with a low-temperature constant temperature cooling bath to ensure that the temperature change of the reaction solution during the reaction process did not exceed room temperature ±2℃. Dicamba was used as the active pesticide.

[0159] A 0.01 mg / mL (25 mL) solution of dicamba was prepared and placed in a quartz bottle. TiO2-coated composite materials (ATT NP1, ATT NP2, ATT NP3) with uniform TiO2 (20 mg) content were added. The mixture was stirred for 30 min in the dark to allow adsorption equilibrium to be reached. Then, the solution was tested under natural light with an intensity of 63.7 mW / cm². 2 Irradiation under simulated sunlight conditions, with continuous stirring at 150 rpm, 1 mL samples were taken every 12 hours for centrifugation. The supernatant was collected and the residual concentration of dicamba was determined by high-performance liquid chromatography (HPLC). The HPLC conditions were: mobile phase V... (乙腈) V (0.1wt％磷酸) =60:40, flow rate 1.0 mL / min, column oven temperature room temperature ± 2℃, UV detection wavelength 220 nm, injection volume 40 μL, dicamba retention time 2.8 min. Simultaneously, the composite material without a buffer layer coated with TiO2 was used as a blank control; test results are as follows: Figure 9 As shown in (a) in the figure.

[0160] Depend on Figure 9 As shown in (a), under light conditions, dicamba was not degraded within 225 hours when used alone. However, adding TiO2 to the dicamba solution resulted in immediate degradation of dicamba, with complete degradation occurring after 72 hours. In contrast, when dicamba was co-cultured with ATT NP1, ATT NP2, or ATT NP3, it was not degraded within 120, 60, and 48 hours, respectively; after the "silent period," the pesticide began to degrade and was completely decomposed after 224, 162, and 120 hours, respectively. These results demonstrate that the buffer layer can delay the degradation process of dicamba, and the onset time of the degradation process can be controlled by adjusting the amounts of ATA and tetraethyl orthosilicate.

[0161] To analyze the composition of the TiO2-coated composite material with a buffer layer and to confirm whether the buffer layer can degrade under sunlight, ATT NP1, ATT NP2, and ATT NP3 were pre-immersed in water, and thermogravimetric analyses were performed under both light and dark conditions. The results are as follows: Figure 9 As shown in (b) of the diagram.

[0162] Depend on Figure 9 As shown in (b), under no-light conditions, the average weight losses of ATT NP3, ATT NP2, and ATT NP1 were 3.8%, 10.8%, and 24.4%, respectively. Under light conditions (natural light intensity of 63.7 mW / cm²), the weight losses of ATT NP3, ATT NP2, and ATT NP1 were... 2 Under the specified conditions, the average weight losses of ATT NP3, ATT NP2, and ATT NP1 were 2.9%, 8.2%, and 17.7%, respectively. Since the TiO2 core does not decompose under these experimental conditions, the weight loss of ATT NP1, ATT NP2, and ATT NP3 is mainly caused by the buffer layer. Therefore, the higher the proportion of the buffer layer in the TiO2-coated composite material, the more significant the weight loss. The weight loss of the TiO2-coated composite material with a buffer layer after light irradiation pretreatment was less than that under no-light conditions, and the difference increased with the increase of the buffer layer thickness. This result indicates that the content of ATT NP decreases after light irradiation, suggesting that the ATT buffer layer is gradually degraded by the reactive oxygen species generated by TiO2 under light irradiation.

[0163] 3. The composite material with a buffer layer coated with TiO2 generates hydroxyl radicals (·OH).

[0164] •OH is one of the reactive oxygen species generated during the photocatalytic degradation of TiO2. Coumarin reacts with •OH to produce fluorescence emission at 450 nm (7-hydroxycoumarin or 7-OHC). In order to evaluate the generation rate of •OH in the composite material with buffer layer coated TiO2, this invention uses coumarin as a scavenging agent.

[0165] First, composite materials (ATT NP1, ATT NP2, or ATT NP3) with a uniform TiO2 (20 mg) buffer layer were dispersed in a 0.05 mM coumarin (50 mL) solution and stirred in the dark for 20 minutes to reach adsorption equilibrium. The mixture was then subjected to natural light with an intensity of 63.7 mW / cm². 2 Irradiation was performed under the specified conditions, with 1 mL of solution taken and centrifuged every 1 hour, retaining the supernatant. The change in fluorescence intensity of the supernatant at 450 nm was measured using a fluorescence spectrophotometer. The test conditions were: excitation wavelength 332 nm, slit width 15 nm, and scanning band 350–600 nm. The test results are as follows: Figure 10 As shown; in Figure 10The values ​​in (a) to (d) represent the ·OH generation rates of TiO2, ATT NP1, ATT NP2, and ATT NP3, respectively.

[0166] Depend on Figure 10 As shown in (a), adding TiO2 to the coumarin solution significantly increased the fluorescence intensity of 7-hydroxycoumarin within 3 hours, indicating the generation of a large amount of ·OH under these conditions. The concentration of ·OH gradually increased with prolonged illumination, continuing until 6 hours. However, according to... Figure 10 As shown in (b) to (d), the TiO2-coated composite material with a buffer layer generates ·OH at a slower rate than TiO2. Specifically, ·OH generated by ATT NP3, ATT NP2, and ATT NP1 was detected after 9, 48, and 72 hours, respectively, with fluorescence intensity reaching peaks at 12, 72, and 96 hours. These experimental results indicate that the ATA buffer layer has a delaying effect on the diffusion of ·OH generated by the photocatalyst into the solution, and this effect increases with increasing buffer layer thickness.

[0167] 4. Release of active components in pesticide controlled-release agents

[0168] This invention determined the drug release characteristics of a time-degradable pesticide controlled-release agent under different environments, and selected dicamba@mSiO2+TiO2 prepared in Comparative Example 3 as a control. Specifically, the pesticide controlled-release agent (dicamba@MATT NP1, 5 mg) prepared in Example 1 or dicamba@mSiO2+TiO2 with the same effective dicamba content was dispersed in 2 mL of distilled water, and divided into two equal portions, each placed in a 50 mL quartz bottle. One portion was tested under natural light intensity of 63.7 mW / cm². 2 One study investigated drug release under light conditions, while the other conducted drug release under dark conditions (as a control). The supernatant was collected by centrifugation every 3 hours, and the concentration of dicamba in the supernatant was measured to calculate the cumulative drug release. Results are as follows: Figure 11 As shown.

[0169] from Figure 11 As shown in (a), the cumulative drug release of the dicamba@mSiO2+TiO2 mixture reached 89% in the dark environment after 24 hours; under natural light, the cumulative drug release was 44% after 24 hours. These results indicate that sunlight has a significant impact on the drug release behavior of dicamba@mSiO2+TiO2. This impact is attributed to the direct contact between the released drug and TiO2, resulting in degradation by reactive oxygen species (·OH) generated by the photocatalytic process. This suggests that the drug release behavior of this formulation is affected by the mixed TiO2, thereby reducing the efficacy of the pesticide.

[0170] from Figure 11As shown in (b), under light and dark conditions, the cumulative drug release of the time-degradable pesticide controlled-release agent (dicamba@MATT NP1) was 75% and 80% after 24 hours, respectively. This indicates that the drug release characteristics of the pesticide controlled-release agent provided by this invention are not affected by light. Furthermore, the drug release experiments demonstrate that the timed barrier (buffer layer) can protect the pesticide from ROS degradation during release; compared to physical mixing methods, this delayed degradation can improve pesticide efficacy.

[0171] 5. Determination of the degradation effect of pesticide residues after the release of controlled-release pesticides

[0172] Four controlled-release pesticide formulations (dicamba@MT NPs, dicamba@MATT NPs, dicamba@mSiO2, and dicamba) were released in the dark for 48 hours. After release, the formulations were dried and then divided into ten portions, placed in glass bottles, and stored under natural light at an intensity of 63.7 mW / cm². 2 Irradiation was performed under the specified conditions, with samples taken every two days. After irradiation, the samples were dissolved in 1 wt% HF, extracted with ethyl acetate, and after solvent removal, dissolved in 1 mL of distilled water. The concentration of dicamba in the solution was then detected using high-performance liquid chromatography (HPLC). The test results are as follows: Figure 12 As shown.

[0173] exist Figure 12 In the experimental results, dicamba in aqueous solution and dicamba in mesoporous silica carrier (dicamba@mSiO2) did not degrade. In contrast, dicamba in dicamba@MT NPs degraded by 77% within 2 days and completely degraded within 10 days. This rapid degradation behavior indicates that the TiO2 core can generate reactive oxygen species and rapidly degrade dicamba. However, the excessively rapid drug degradation process implies a significant risk of degradation of the active ingredient in this formulation during storage and use. Compared to dicamba@MT NPs, the dicamba@MATT NP1 provided by this invention exhibits a lower degradation rate of pesticide residues and a silent period. The herbicide in this controlled-release pesticide formulation did not degrade within the first 12 days, and its degradation process began from day 14. Dicamba was 89% degraded within 20 days. The experimental results show that pesticide residues in the delayed-degrading controlled-release pesticide formulation provided by this invention can be degraded, and this nano-formulation has the potential to reduce the environmental risks caused by pesticide residues. Furthermore, the delayed degradation effect means that pesticide residues are degraded without affecting the efficacy of the herbicide.

[0174] 6. Pot experiment of time-degradable pesticide controlled-release agent

[0175] MCPA@MATT NP1 and 480 g / L commercially available MCPA aqueous solution (purchased from Shandong Zhongnong United Biotechnology Co., Ltd.) were used as experimental agents to treat the target weed (Dendrobium nobile) at effective ingredient concentrations of 216, 108, 54, 27, 13.5, and 6.75 g·a·i / ha (g·a·i / ha). A blank control without treatment was also included. The growth rate (GR) was calculated by measuring the fresh weight of the treated weeds on day 20 after treatment. 50 To evaluate differences in drug activity. GR 50 This indicates the dosage of herbicide (dicamba) required to suppress weed growth by 50%. Results are as follows: Figure 13 As shown. In Figure 13 (a) is a picture of Artemisia annua on day 20 after application; (b) is the efficacy curve of dicamba@MATT NP1; (c) is the efficacy curve of commercially available dicamba aqueous solution.

[0176] Depend on Figure 13 It can be seen that the GR of dicamba@MATT NP1 50 The value is significantly lower than that of commercially available dicamba aqueous solution, indicating that the pesticide controlled-release agent provided by the present invention has a better herbicidal effect, suggesting that the control effect of the formulation is not affected by the TiO2 core due to the presence of the timed barrier layer (buffer layer).

[0177] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a time-delayed self-degrading type pesticide controlled release agent, characterized by, The method includes: (1) Under light-protected conditions, in the presence of alkaline conditions and alcohol solvent, TiO2, buffer layer monomer ATA, and tetraethyl orthosilicate are mixed for the first time to obtain a composite material with a buffer layer coated with TiO2; the molar ratio of the buffer layer monomer ATA to tetraethyl orthosilicate is 1:0.8-1.2; based on the amount of TiO2 being 100mg, the total mass of the buffer layer monomer ATA and tetraethyl orthosilicate is 10-350mg; wherein, the buffer layer monomer ATA is the compound shown in formula (I); Equation (I) (2) In the presence of solvent I, the composite material with TiO2 coated by the buffer layer is mixed with the template agent to obtain mixture II; the solvent I is water and / or ethanol; The template agent is selected from at least one of hexadecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and octadecyltrimethoxysilane; (3) Under light-protected and alkaline conditions, the mixture II is mixed with tetraethyl orthosilicate and silane coupling agent in a third mixing process, and then the template agent is removed to obtain the nanocarrier; The silane coupling agent is selected from at least one of 3-aminopropyltriethoxysilane, (3-aminopropyl)dimethylethoxysilane, and aminopropylaminoethyltrimethoxysilane; (4) Under light-protected conditions, the nanocarrier is mixed with the active pesticide component in a fourth mixing process to obtain a time-degradable pesticide controlled-release agent; The mass ratio of the nanocarrier to the active pesticide component is 1:0.1-10.

2. The method according to claim 1, wherein, In composite materials with TiO2 coated with a buffer layer, the thickness of the buffer layer is 10-200 nm.

3. The method according to claim 1, wherein, The average particle size of the TiO2 is 30-60 nm.

4. The method according to claim 1, wherein, The average pore size of the nanocarrier is 1-10 nm.

5. The method according to any one of claims 1-4, wherein, In step (2), the mass ratio of the TiO2-coated composite material to the template agent in the buffer layer is 1:3-4.

6. The method according to any one of claims 1-4, wherein, In step (3), relative to 100 mg of the composite material with TiO2 coated by the buffer layer, the amount of tetraethyl orthosilicate is 3-5 g and the amount of silane coupling agent is 0.8-1.0 g.

7. The method according to any one of claims 1-4, wherein, In steps (1) and (3), the pH value of the alkaline conditions is 9-14.

8. The method according to any one of claims 1-4, wherein, The conditions for the first mixing include: a temperature of 55-65°C and a time of 5-7 hours; and / or The conditions for the second mixing include: mixing under ultrasonic conditions for 20-30 minutes; and / or The conditions for the third mixing include: a temperature of 25-35°C and a time of 5-7 hours; and / or The conditions for the fourth mixing include: a temperature of 25-35℃ and a time of 12-24h.

9. A time-degradable pesticide controlled-release agent prepared by the method according to any one of claims 1-8.

10. The time-degradable pesticide controlled-release agent according to claim 9, wherein, The time-degradable pesticide controlled-release agent contains a photocatalytic degradation core, a timed buffer layer, a drug loading layer, and pesticide active components located on the loading layer.

11. The time-degrading, self-degrading pesticide controlled-release agent according to claim 10, wherein, The photocatalytic degradation core is titanium dioxide; the drug loading layer is mesoporous silicon; and the material of the timing buffer layer is sensitive to reactive oxygen species.

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