Application of quaternized copolymer in preparation of pesticide sustained-release agent and pesticide sustained-release agent

Abstract

The invention discloses an application of a quaternized copolymer in preparation of a pesticide sustained-release agent and the pesticide sustained-release agent, and belongs to the technical field of functional polymer materials and pesticide controlled release. The quaternized copolymer is prepared from 1, 3, 5-tribromomethyl benzene and 1, 4-dimethylpiperazine through a reaction, and can be applied to preparation of a pesticide slow-release agent. The quaternized copolymer shows excellent loading capacity to pesticides, also has the characteristic of environmental stimulation responsiveness, can regulate and control the release rate of the pesticides through external environmental stimulation (such as pH, ionic strength and the like), remarkably improves the utilization rate of the pesticides and reduces environmental pollution, and is suitable for preparing high-efficiency and low-toxicity pesticide sustained-release agents in the agricultural field.

Description

Technical Field

[0001] This invention relates to the fields of polymer functional materials and pesticide controlled release technology, and particularly to the application of a quaternized copolymer in the preparation of pesticide slow-release agents and the pesticide slow-release agent itself. Background Technology

[0002] With the rapid development of modern agriculture, pesticides play a crucial role in pest and disease control and ensuring food security. However, traditional pesticide formulations (such as emulsifiable concentrates and wettable powders) suffer from problems such as rapid release of active ingredients, short duration of action, and low utilization rate. This not only leads to pesticide waste and increased usage costs but also easily causes soil pollution, groundwater residues, and ecological risks. Statistics show that the field utilization rate of conventional pesticides is less than 30%, with the remainder entering the environment through volatilization, leaching, or runoff, posing potential harm to non-target organisms and ecosystems. Therefore, developing pesticide formulations with controlled-release properties to achieve slow release and long-lasting effects of active ingredients has become an important direction for promoting pesticide formulation upgrades.

[0003] The core principle of pesticide slow-release technology is to regulate the release rate of pesticide active ingredients through physical or chemical means, enabling the active ingredients to exert their effects continuously and stably throughout the crop growth cycle, thereby reducing the number of applications and improving utilization. Early slow-release agents mainly used natural polymer materials (such as starch and cellulose) or synthetic resins as carriers, but these had limitations such as low pesticide loading, unstable slow-release performance, and poor biodegradability. Therefore, the development of a new type of slow-release agent that is low-cost, environmentally friendly, and can precisely regulate the release rate is urgently needed. New pesticide slow-release agents can not only improve pesticide utilization, reduce usage costs, and reduce environmental pollution, but also effectively address the shortcomings of traditional pesticide formulations and existing slow-release formulations, providing strong support for the green and sustainable development of agriculture. Summary of the Invention

[0004] Purpose of the invention: The present invention aims to provide an application of quaternized copolymers in the preparation of pesticide slow-release agents and pesticide slow-release agents. The quaternized copolymers, after being loaded with pesticides, can achieve slow release of pesticides, improve weeding efficiency and reduce pesticide side effects.

[0005] Technical solution: In a first aspect, the present invention provides the application of a quaternized copolymer in the preparation of pesticide slow-release agents, wherein the quaternized copolymer is prepared by reacting 1,3,5-tribromomethylbenzene with 1,4-dimethylpiperazine.

[0006] Furthermore, the preparation method of the quaternized copolymer includes the following steps:

[0007] The target product was prepared by dissolving 1,3,5-tribromomethylbenzene and 1,4-dimethylpiperazine in a polar aprotic solvent and reacting them under heating.

[0008] Further, the molar ratio of the 1,3,5-tribromomethylbenzene to the 1,4-dimethylpiperazine is (0.5~1.5):(1~2).

[0009] Furthermore, the polar aprotic solvent is N,N-dimethylacetamide, and the N,N-dimethylacetamide accounts for 30% to 60% of the volume of the reaction vessel.

[0010] Furthermore, the reaction temperature of the heating reaction is 120-180 °C, and the reaction time is 24-60 h.

[0011] Furthermore, after the heating reaction is completed, the product is filtered, washed, and dried. The washing reagent is a mixture of water and N,N-dimethylacetamide, and the drying temperature is 60-80 °C.

[0012] Furthermore, the pesticide slow-release agent includes the quaternized copolymer, which is a pesticide carrier, and the pesticide is 2,4-D-Na.

[0013] Furthermore, the pesticide slow-release agent also includes Cl... - and SO4 2- Salt is used to regulate the slow-release rate of pesticides.

[0014] Furthermore, the pesticide slow-release agent can also be released in a controlled manner by adjusting the pH, with pH=5~9.

[0015] In a second aspect, the present invention also provides a pesticide slow-release agent comprising a quaternized copolymer, wherein the quaternized copolymer is prepared by reacting 1,3,5-tribromomethylbenzene with 1,4-dimethylpiperazine.

[0016] Furthermore, the aforementioned pesticide slow-release agents may also include those containing Cl. - and SO4 2- Salt.

[0017] Invention Principle: This invention utilizes 1,3,5-tribromomethylbenzene (TBMB) as a tridentate node and 1,4-dimethylpiperazine (DMP) as a linear connecting unit to construct a permanently positively charged porous organic polymer—quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) (PBMDM)—through a one-step quaternization reaction. This polymer can serve as a carrier for the slow release of pesticides. The zeta potential on the surface of the quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) changes significantly with the pH of the solution. By influencing the electrostatic and other interactions between the carrier and the pesticide 2,4-D-Na through changes in environmental pH and ionic strength, this imparts multi-stimulus responsiveness to both pH and ionic strength in the pesticide slow-release agent. Therefore, this pesticide slow-release agent can achieve controlled pesticide release by controlling the environmental pH or ionic strength.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The quaternized copolymer adopts a one-step quaternization polymerization process by solvothermal method, and directly constructs the polymer skeleton through the quaternization reaction of 1,3,5-tribromomethylbenzene and 1,4-dimethylpiperazine, without the need for subsequent modification to introduce quaternary ammonium groups, which has the characteristics of simplified steps and easy large-scale production; (2) The prepared quaternized copolymer carrier has a stable chemical structure in a wide pH range, and its loading performance for the anionic pesticide 2,4-D-Na is not affected by the drastic fluctuation of environmental pH, which can ensure the consistency and stability of the release behavior of the slow-release agent under different environmental conditions; (3) The slow-release agent has dual stimulation response to pH and ionic strength, and can achieve precise controlled release of pesticides by regulating environmental conditions; (4) The quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) exhibits excellent loading capacity for the pesticide 2,4-D-Na, with a maximum loading capacity of up to 699.92 mg / g. Attached Figure Description

[0019] Figure 1 Synthetic route diagram for quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine);

[0020] Figure 2 FTIR spectra of 1,3,5-tribromomethylbenzene (TBMB), 1,4-dimethylpiperazine (DMP), quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) (PBMDM) and pesticide 2,4-D-Na;

[0021] Figure 3 The loading capacity of PBMDM for different initial concentrations of 2,4-D-Na is shown in the figure.

[0022] Figure 4The figure shows the Zeta potential of PBMDM and its loading capacity for 2,4-D-Na at different pH values.

[0023] Figure 5 Figures show the sustained-release behavior of PBMDM@2,4-D-Na in different solutions; where a) is the sustained-release graph of PBMDM@2,4-D-Na at different pH values, and b) is the sustained-release graph of PBMDM@2,4-D-Na in salt solution.

[0024] Figure 6 Figure for herbicide activity study of PBMDM@2,4-D-Na. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0026] Example 1

[0027] The preparation method of the quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) sustained-release agent is as follows:

[0028] 0.3568 g of 1,3,5-tribromomethylbenzene and 0.2 mL of 1,4-dimethylpiperazine were weighed and placed in a 10 mL high-pressure reactor lined with polytetrafluoroethylene. Then, 5 mL of N,N-dimethylacetamide was added as a solvent. The solid was completely dissolved under ultrasonic stirring. The reactor was then sealed and reacted at a constant temperature of 150 °C for 48 h. After the reaction was complete, the mixture was cooled to room temperature, filtered, and the solid product was washed with N,N-dimethylacetamide and water, respectively. Finally, the solid was dried at 60 °C to obtain a yellow-brown solid product, quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) sustained-release agent (PBMDM).

[0029] The synthetic route for the quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) sustained-release agent is shown in the attached diagram. Figure 1 The porous organic polymer was constructed by a one-step quaternization reaction using 1,3,5-tribromomethylbenzene (TBMB) as a tridentate node and 1,4-dimethylpiperazine (DMP) as a linear linking unit.

[0030] Example 2

[0031] The preparation method of the quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) sustained-release agent is as follows:

[0032] 0.1784 g of 1,3,5-tribromomethylbenzene and 0.2 mL of 1,4-dimethylpiperazine were weighed and placed in a 10 mL high-pressure reactor lined with polytetrafluoroethylene. Then, 4 mL of N,N-dimethylacetamide was added as a solvent. The solid was completely dissolved under ultrasonic stirring. The reactor was then sealed and reacted at a constant temperature of 150 °C for 48 h. After the reaction was complete, the mixture was cooled to room temperature, filtered, and the solid product was washed with N,N-dimethylacetamide and water, respectively. Finally, the solid was dried at 60 °C to obtain a yellow-brown solid product, quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) sustained-release agent (PBMDM).

[0033] Example 3

[0034] The preparation method of the quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) sustained-release agent is as follows:

[0035] 0.5353 g of 1,3,5-tribromomethylbenzene and 0.2 mL of 1,4-dimethylpiperazine were weighed and placed in a 10 mL high-pressure reactor lined with polytetrafluoroethylene. Then, 6 mL of N,N-dimethylacetamide was added as a solvent. The solid was completely dissolved under ultrasonic stirring. The reactor was then sealed and reacted at a constant temperature of 150 °C for 48 h. After the reaction was complete, the mixture was cooled to room temperature, filtered, and the solid product was washed with N,N-dimethylacetamide and water, respectively. Finally, the solid was dried at 60 °C to obtain a yellow-brown solid product, quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) sustained-release agent (PBMDM).

[0036] The following section describes the structural characterization and test results of the quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) prepared in Example 1.

[0037] (1) FTIR

[0038] Infrared characterization was performed on samples before and after pesticide loading onto PBMDM, see [link to relevant documentation]. Figure 2The steps for preparing a pesticide slow-release agent by loading a quaternized copolymer are as follows: 0.50 g of the PBMDM pesticide slow-release carrier from Example 1 is weighed into an Erlenmeyer flask, and 500 mL of a 500 mg / L 2,4-D-Na solution is added simultaneously. The mixture is shaken in a shaker at 110 rpm for 12 h, filtered, and dried to obtain the 2,4-D-Na slow-release agent (PBMDM@2,4-D-Na). The curves in the figure represent: 1,3,5-tribromomethylbenzene (TBMB), 1,4-dimethylpiperazine (DMP), quaternized poly(1,3,5-tribromomethylbenzene-co-1,4-dimethylpiperazine) (PBMDM), pesticide slow-release agent PBMDM@2,4-D-Na, and pesticide 2,4-D-Na, respectively.

[0039] like Figure 2 As shown, TBMB is at 3023, 2971, 1604 / 1435, and 581 cm. -1 The characteristic peaks at these locations represent the stretching vibrations of aromatic CH, bromomethyl CH, the aromatic C=C skeleton, and C-Br, respectively. DMP values ​​at 2936 / 2791, 1455, 1370, 1289-1013, and 919 / 805 cm⁻¹ represent these vibrations. -1 The characteristic peaks at 581 cm⁻¹ represent aliphatic CH stretching vibration, methylene bending vibration, methyl symmetric bending vibration, CN stretching vibration, and piperazine ring skeletal vibration, respectively. PBMDM at 581 cm⁻¹... -1 The complete disappearance of the C-Br peak and 1113 cm -1 New CN + The appearance of stretching vibration peaks confirms the successful quaternization reaction between the bromomethyl group of TBMB and the tertiary amine group of DMP. Furthermore, PBMDM shows peaks at 1633, 1460-1358, and 1179-1020 cm⁻¹. -1 The characteristic peaks at this point represent C=C stretching vibration, CH bending vibration, and CN / CN. + Stretching vibration.

[0040] For PBMDM loaded with 2,4-D-Na, at 1614 cm⁻¹ -1 (Aromatic C=C), 1402 cm -1 (Carboxylate group), 1284cm -1 (Aromatic ether COC) and 804 / 763 cm -1 The characteristic peak at (C-Cl) confirms the successful loading of 2,4-D-Na.

[0041] (2) Effect of initial concentration on adsorption

[0042] 50 mg PBMDM and 50 mL 2,4-D-Na solutions (25, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200 mg / L, T=298 K, pH=5) were shaken for 12 h, and the loading at different initial concentrations was determined and calculated.

[0043] Figure 3 The effect of initial concentration on the loading of 2,4-D-Na on PBMDM is shown in the figure. As the initial concentration increases, the loading of 2,4-D-Na on PBMDM increases significantly. At 298 K, as the initial concentration increases from 25 mg / L to 1200 mg / L, the loading increases from 23.45 mg / g to 699.92 mg / g.

[0044] (3) Zeta potential of PBMDM and loading capacity of 2,4-D-Na at different pH values

[0045] Add 50 mg PBMDM to 50 mL of 100 mg / L 2,4-D-Na solution (pH range 2–12, adjusted with 0.1 M NaOH and 0.1 M HCl), shake in a 110 rpm shaker for 12 h, and measure and calculate the loading at different pH values.

[0046] Depend on Figure 4 It was found that the Zeta potential of PBMDM varied from +28.4 mV to +13.0 mV within the pH range of 2–12, remaining consistently positive. This characteristic indicates that PBMDM can be loaded with the pesticide 2,4-D-Na over a wide pH range. When the solution's pH range was 4–10, it exhibited a high loading capacity for 2,4-D-Na, ensuring the consistency and stability of the slow-release agent's release behavior under different environmental conditions.

[0047] (4) Effects of different environmental conditions on the sustained-release behavior of PBMDM@2,4-D-Na sustained-release agent

[0048] Weigh 0.50 g of the above PBMDM pesticide slow-release carrier into an Erlenmeyer flask, and add 500 mL of 500 mg / L 2,4-D-Na solution. Shake in a shaker at 100 rpm for 12 h, filter, and dry to obtain 2,4-D-Na slow-release agent (PBMDM@2,4-D-Na). A sustained-release study of PBMDM@2,4-D-Na was conducted. 50.0 mg of PBMDM@2,4-D-Na (2,4-D-Na loading rate 29.97%) was weighed and added to a dialysis bag with a molecular weight cutoff of 8000 g / mol. The dialysis bag was placed in a 250 mL beaker, and 150 mL of sustained-release solutions at different pH values ​​(pH = 5.0, 7.0, and 9.0, adjusted by 0.1 M NaOH and 0.1 M HCl) or salt solutions (0.025 M NaCl, 0.05 M NaCl, 0.05 M Na2SO4, pH approximately 7.0) were added. The mixture was shaken at 100 rpm at room temperature. At regular intervals, 5 mL of the supernatant was collected, and 5 mL of the same solution was added to replenish it. Subsequently, the concentration of 2,4-D-Na in the filtrate was measured at 229.5 nm using a UV-Vis spectrophotometer, and the cumulative release rate was calculated according to the formula.

[0049] Depend on Figure 5 a) It can be seen that under different pH conditions, the cumulative release rate of 2,4-D-Na from PBMDM@2,4-D-Na gradually increases with time. Under pH conditions of 5.0–9.0, the release rate after 260 h is 29.24%–35.96%. Figure 5 a) It can be seen that the pH of the solution has a significant impact on the sustained-release capacity of PBMDM@2,4-D-Na.

[0050] Depend on Figure 5 (b) It can be seen that the release rate of PBMDM@2,4-D-Na sustained-release agent varies significantly under different ionic strengths. After 6 h, the cumulative release rate of 2,4-D-Na is: 98.83% (0.05 M Na2SO4) > 75.82% (0.05 M NaCl) > 41.87% (0.025 M NaCl). By adjusting the external environment (especially pH and ionic strength), the delivery curve of PBMDM@2,4-D-Na can be effectively modulated, highlighting the potential of PBMDM as a stimulus-responsive charge carrier system in targeted delivery or controlled release applications.

[0051] (5) Herbicidal activity

[0052] Five 9 cm diameter petri dishes were prepared, each containing 10 mL of test solution (a: deionized water, b: 0.025 M NaCl solution, c: deionized water + PBMDM, d: 0.025 M NaCl + PBMDM@2,4-D-Na, e: 100 ppm 2,4-D-Na, where the amount of 2,4-D-Na in groups d and e was the same, and the amount of slow-release carrier in groups c and d was the same). A layer of filter paper was placed inside each petri dish, and 20 rapeseed seeds were placed on the filter paper. The plants were grown in an incubator at 25 °C, 75% humidity, and 3000 lx light intensity. The first three days were completely dark, followed by four days of alternating day and night (12 / 12). The root length of the rapeseed was measured under different conditions, and the fresh and dry weights of the seeds were compared.

[0053] like Figure 6 As shown, 0.025 M NaCl solution had no side effects on rapeseed growth and significantly promoted root and stem growth. Furthermore, PBMDM had no significant effect on rapeseed growth, indicating that PBMDM has good biocompatibility and is suitable for use as a pesticide carrier. Regarding rapeseed growth, the fresh and dry weights of rapeseed treated with PBMDM@2,4-D-Na in 0.025 M NaCl medium were lower than those treated with the same dosage and concentration of 2,4-D-Na aqueous solution. These results indicate that PBMDM@2,4-D-Na has good herbicidal activity, which is influenced by the ionic strength of the release medium.

Claims

1. The application of a quaternized copolymer in the preparation of pesticide slow-release agents, characterized in that, The quaternized copolymer was prepared by reacting 1,3,5-tribromomethylbenzene with 1,4-dimethylpiperazine.

2. The application of the quaternized copolymer according to claim 1 in the preparation of pesticide slow-release agents, characterized in that, The preparation method of the quaternized copolymer includes the following steps: The target product was prepared by dissolving 1,3,5-tribromomethylbenzene and 1,4-dimethylpiperazine in a polar aprotic solvent and reacting them under heating.

3. The application of the quaternized copolymer according to claim 2 in the preparation of pesticide slow-release agents, characterized in that, The molar ratio of 1,3,5-tribromomethylbenzene to 1,4-dimethylpiperazine is (0.5~1.5):(1~2).

4. The application of the quaternized copolymer according to claim 2 in the preparation of pesticide slow-release agents, characterized in that, The polar aprotic solvent is N,N-dimethylacetamide.

5. The application of the quaternized copolymer according to claim 4 in the preparation of pesticide slow-release agents, characterized in that, The N,N-dimethylacetamide accounts for 30% to 60% of the volume of the reaction vessel.

6. The application of the quaternized copolymer according to claim 2 in the preparation of pesticide slow-release agents, characterized in that, The heating reaction is carried out at a temperature of 120-180 °C for 24-60 h.

7. The application of the quaternized copolymer according to claim 2 in the preparation of pesticide slow-release agents, characterized in that, After the heating reaction is completed, the product is filtered, washed and dried. The washing reagent is a mixture of water and N,N-dimethylacetamide, and the drying temperature is 60-80 °C.

8. The application of the quaternized copolymer according to claim 1 in the preparation of pesticide slow-release agents, characterized in that, The pesticide slow-release agent also includes Cl. - and SO4 2- The salt, wherein the pesticide is 2,4-D-Na.

9. A pesticide slow-release agent, characterized in that, The pesticide slow-release agent includes a quaternized copolymer, which is prepared by reacting 1,3,5-tribromomethylbenzene with 1,4-dimethylpiperazine.

10. The pesticide slow-release agent according to claim 9, characterized in that, The pesticide slow-release agent also contains Cl - and SO4 2- Salt.

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