Preparation of a Modified Polylactic Acid Drug-Loading Material and Its Application in Pesticide Formulations

Abstract

The present invention relates to the technical field of pesticide formulations, and discloses the preparation of a modified polylactic acid drug-loading material and its application in pesticide formulations. In the present invention, chlorpyrifos is used as the core material, and the modified polylactic acid drug-loading material is used as the wall material to prepare a chlorpyrifos-modified polylactic acid material. Mesoporous silica and graphene oxide are used to improve the mechanical properties of the material and the adsorption effect on pesticide formulations. Polylactic acid is grafted onto the surface of lignin to increase the degree of crosslinking, further improving the mechanical properties and encapsulation effect of the drug-loading material. The combined action of the two has a good synergistic effect. All raw materials are biodegradable materials and will not cause secondary pollution to the environment after use, which is of great significance for the development of efficient, environmentally friendly and green agriculture. The modified polylactic acid drug-loading material prepared by the present invention has the advantages of good green environmental protection, as well as good encapsulation rate and comprehensive slow-release effect for pesticide formulations.

Description

Technical Field

[0001] The present invention relates to the technical field of pesticide formulations, and specifically to the preparation of a modified polylactic acid drug-loading material and its application in pesticide formulations. Background Art

[0002] China is not only a large population country but also a large agricultural country. The development of agricultural production is inseparable from the use of pesticides. Pesticides play an important role in preventing and controlling biological disasters, increasing crop yields, and promoting the sustainable and stable growth of agricultural production. However, traditional pesticides have drawbacks such as solvent pollution of the environment, rapid loss of active ingredients, and poor drug efficacy during use. Some studies have shown that the use of drug carriers can significantly extend the action time of pesticides, improve the utilization efficiency, and thus reduce their impact on the ecological environment. Therefore, the research and development of drug-loading materials have become a hot topic for researchers.

[0003] Biodegradable materials can be classified into natural polymer materials and fully synthetic biodegradable polymer materials according to their sources. Natural polymer materials are widely used in the medical field due to their low toxicity, low pollution, and easy film-forming properties. However, their mechanical strength is low, so their application is limited. Therefore, the development of low-cost and good mechanical property drug-loading materials has become a hot topic in the field of carrier materials.

[0004] Polylactic acid has properties such as non-toxicity, non-irritation, good plasticity, and good biocompatibility, and is widely used in the field of carrier materials and has become a drug-controlled release carrier that has received much attention. However, the presence of a large number of hydrophobic group ester bonds in the molecular structure of polylactic acid leads to poor hydrophilicity, reduces its biocompatibility, and its strength often cannot meet the requirements. Therefore, it is necessary to modify it to prepare a modified polylactic acid drug-loading material to meet the needs of modern pesticide formulations. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides the preparation of a modified polylactic acid drug-loading material and its application in pesticide formulations. The prepared modified polylactic acid drug-loading material has the advantages of good green environmental protection, as well as good encapsulation efficiency and comprehensive slow-release effect for pesticide formulations.

[0007] (2) Technical Solutions

[0008] One of the purposes of the present invention is to provide a preparation method of a modified polylactic acid drug-loading material, and the preparation method is as follows:

[0009] Add graphene oxide diol, mesoporous silica modified lignin, and L-lactide into a flask, stir and disperse them. Then add stannous octoate toluene solution with a concentration of 0.1 - 0.2 mol / L, stir and mix evenly. Heat up to 65 - 75 °C, and remove toluene by vacuum distillation. Fill the flask with nitrogen, evacuate it repeatedly three times, seal the flask, and place it in a vacuum oven at 150 - 175 °C for melt ring-opening polymerization reaction for 3 - 6 h. After the reaction is completed, add dichloromethane and filter by suction, wash with ethanol, and dry to obtain the modified polylactic acid drug-loading material.

[0010] Preferably, the mass ratio of the graphene oxide diol, mesoporous silica modified lignin, and L-lactide is 0.1 - 0.5:0.1 - 0.5:1.

[0011] Preferably, the preparation method of the mesoporous silica modified lignin is as follows: Add lignin into deionized water, adjust the pH to 10 - 11 with 10% sodium hydroxide aqueous solution, heat up to 85 - 95 °C, add amino-functionalized mesoporous silica and 37% formaldehyde aqueous solution, stir and react for 2 - 5 h. After the reaction is completed, wash with dilute hydrochloric acid and deionized water in sequence, and dry to obtain the mesoporous silica modified lignin.

[0012] Preferably, the mass ratio of the lignin to the amino-functionalized mesoporous silica is 1:0.5 - 1.

[0013] Preferably, the preparation method of the graphene oxide diol is as follows:

[0014] (1) Add graphene oxide into deionized water, disperse it by ultrasonic wave, then add sodium hydroxide and vinyl chloride, stir and disperse, react by ultrasonic wave for 2 - 4 h, wash by centrifugation with dilute hydrochloric acid, and dry to obtain vinylated graphene oxide;

[0015] (2) Under a nitrogen atmosphere, add diethanolamine into an ethanol solvent, stir and disperse it, then add vinylated graphene oxide, heat up to 50 - 70 °C, stir and react for 12 - 24 h. After the reaction is completed, distill under reduced pressure, wash with deionized water, and dry to obtain the graphene oxide diol.

[0016] Preferably, in (1), the mass ratio of the graphene oxide, sodium hydroxide, and vinyl chloride is 1:40 - 55:25 - 50.

[0017] Preferably, in (2), the mass ratio of the diethanolamine to the vinylated graphene oxide is 0.5 - 1.5:1.

[0018] Another object of the present invention is the application of the modified polylactic acid drug-loading material in pesticide formulations. Specifically, chlorpyrifos and polylactic acid are added to dichloromethane solvent, where the mass ratio of chlorpyrifos to polylactic acid is 1:2 - 5. Stir to dissolve, then add an aqueous solution of polyvinyl alcohol - gelatin with a mass fraction of 1.5%, and disperse and emulsify it for 2 - 4 min using a high-speed internal cutting disperser. Stir continuously at a constant speed of 400 r / min for 3 - 5 h, filter by suction, wash with deionized water, and dry to obtain the chlorpyrifos - modified polylactic acid material.

[0019] (III) Beneficial technical effects

[0020] In the present invention, lignin reacts with amino-functionalized mesoporous silica and formaldehyde through the Mannich reaction to obtain mesoporous silica-modified lignin. Graphene oxide reacts with vinyl chloride through a substitution reaction to obtain vinylated graphene oxide, and then it undergoes a Michael addition reaction with diethanolamine to obtain graphene oxide-containing diol. Using stannous octoate as a catalyst, the graphene oxide-containing diol, mesoporous silica-modified lignin, and L-lactide undergo a melt ring-opening polymerization reaction to obtain the modified polylactic acid drug-loading material. Using an aqueous solution of polyvinyl alcohol - gelatin as the continuous phase and a dichloromethane solution of chlorpyrifos and the modified polylactic acid drug-loading material as the organic phase, mix them evenly, disperse and emulsify, and dry to obtain the chlorpyrifos - modified polylactic acid material.

[0021] In the present invention, the graphene and mesoporous silica used are inorganic materials, showing strong hydrophilic and oleophobic properties, which is not conducive to the dispersion of graphene and mesoporous silica in the matrix material. By introducing organic substances into graphene and mesoporous silica through reactions, the affinity of graphene and mesoporous silica with the organic phase is greatly enhanced. Introducing them into the modified polylactic acid material can enhance the mechanical properties and hydrophilic effect of polylactic acid. It can not only increase the drug loading capacity of the drug-loading material, but also, because the surfaces of graphene and mesoporous silica contain polar groups, they can generate van der Waals forces, hydrogen bonds and other interactions with pesticide formulations such as chlorpyrifos, increase the encapsulation effect, delay the release of pesticide formulations, make them not easy to lose, and improve the utilization rate.

[0022] In addition, in the present invention, the hydroxyl groups contained in lignin are used to carry out a melt ring-opening polymerization reaction with L-lactide, grafting a polylactic acid structure on the surface of lignin, which can generate a huge cross-linked network structure and has a good encapsulation effect on pesticide formulations. When the concentration of the external pesticide formulation is low, it can slowly release the pesticide formulation into the environment and improve the utilization rate of the pesticide formulation.

[0023] The present invention performs a melt ring-opening polymerization reaction on graphene oxide diol, mesoporous silica-modified lignin, and L-lactide to obtain a modified polylactic acid drug-loading material. The polylactic acid is modified by graphene oxide diol and mesoporous silica-modified lignin to improve the molding stability and compatibility of the drug-loading material. Utilizing the slow-release effects of graphene oxide, mesoporous silica, and lignin on pesticide formulations, it has a good synergistic effect, and all raw materials are biodegradable materials, which will not cause secondary pollution to the environment after use. It is of great significance for the development of efficient, environmentally friendly, and green agriculture. Brief Description of the Drawings

[0024] Figure 1 It is the scanning electron microscope picture of Example 3. As can be seen from the figure, the spheroidization effect is good, the spheres are regular in shape and smooth on the surface, with better protection effect for the core material and good mechanical strength. Detailed Embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0026] Preparation of amino-functionalized mesoporous silica: Add 1 g of cetyltrimethylammonium bromide and 70 mL of ammonia water to deionized water, stir to dissolve, then add 5 g of tetraethyl orthosilicate and aminopropyltriethoxysilane thereto, and stir and react for 8 h. After the reaction is completed, crystallize, filter, wash, and dry to obtain amino-functionalized mesoporous silica.

[0027] Preparation of graphene oxide: Add 3 g of natural graphite powder to 140 mL of concentrated sulfuric acid, stir in an ice-water bath for 1 h, then add 1.5 g of sodium nitrate thereto, stir and react for 10 min, add 9 g of potassium permanganate thereto, continue to stir for 20 min, heat up to 90 °C, react for 20 min, then add 500 mL of deionized water thereto, stir and react for 10 min, then add hydrogen peroxide with a mass fraction of 30%, continue to stir and react for 2 h. After the reaction is completed, wash successively with dilute hydrochloric acid and deionized water, centrifuge, and dry to obtain graphene oxide.

[0028] Example 1

[0029] (1) Add 10 g of lignin to deionized water, adjust the pH to 10 with a 10% aqueous sodium hydroxide solution, heat up to 95 °C, add 6 g of amino-functionalized mesoporous silica and an aqueous formaldehyde solution with a mass fraction of 37% thereto, stir and react for 4 h. After the reaction is completed, wash successively with dilute hydrochloric acid and deionized water, and dry to obtain mesoporous silica-modified lignin.

[0030] (2) Add 1 g of graphene oxide to deionized water, ultrasonically disperse it, then add 40 g of sodium hydroxide and 30 g of vinyl chloride thereto, stir and disperse, ultrasonically react for 3 h, wash by centrifugation with dilute hydrochloric acid, and dry to obtain vinylated graphene oxide.

[0031] (3) Under a nitrogen atmosphere, add 5 g of diethanolamine to an ethanol solvent, stir and disperse, then add 4 g of vinylated graphene oxide thereto, heat up to 60 °C, stir and react for 24 h. After the reaction, perform vacuum distillation, wash with deionized water, and dry to obtain graphene oxide-containing diol.

[0032] (4) Add 1 g of graphene oxide-containing diol, 1 g of mesoporous silica-modified lignin, and 10 g of L-lactide to a flask, stir and disperse, then add a stannous octoate toluene solution with a concentration of 0.15 mol / L thereto, stir and mix evenly, heat up to 70 °C, vacuum distill to remove toluene, fill the flask with nitrogen and evacuate it repeatedly three times, seal the flask, and place it in a vacuum oven at 160 °C for melt ring-opening polymerization reaction for 5 h. After the reaction, add dichloromethane thereto for suction filtration, wash with ethanol, and dry to obtain a modified polylactic acid drug-loading material.

[0033] (5) Add 2 g of chlorpyrifos and 4 g of the modified polylactic acid drug-loading material to a dichloromethane solvent, stir to dissolve, then add a polyvinyl alcohol-gelatin aqueous solution with a mass fraction of 1.5% thereto, disperse and emulsify with a high-speed internal cutting disperser for 3 min, continuously stir at a constant speed of 400 r / min for 3 h, perform suction filtration, wash with deionized water, and dry to obtain a chlorpyrifos-modified polylactic acid material.

[0034] Example 2

[0035] (1) Add 10 g of lignin to deionized water, adjust the pH to 11 with a 10% aqueous sodium hydroxide solution, heat up to 85 °C, add 10 g of aminated mesoporous silica and an aqueous formaldehyde solution with a mass fraction of 37% thereto, stir and react for 5 h. After the reaction, wash successively with dilute hydrochloric acid and deionized water, and dry to obtain mesoporous silica-modified lignin.

[0036] (2) Add 1 g of graphene oxide to deionized water, ultrasonically disperse it, then add 55 g of sodium hydroxide and 30 g of vinyl chloride thereto, stir and disperse, ultrasonically react for 4 h, wash by centrifugation with dilute hydrochloric acid, and dry to obtain vinylated graphene oxide.

[0037] (3) Under a nitrogen atmosphere, add 5 g of diethanolamine to an ethanol solvent, stir and disperse, then add 4 g of vinylated graphene oxide thereto, heat up to 70 °C, stir and react for 15 h. After the reaction, perform vacuum distillation, wash with deionized water, and dry to obtain graphene oxide-containing diol.

[0038] (4) Add 2 g of graphene oxide diol, 2 g of mesoporous silica modified lignin, and 10 g of L-lactide into a flask, stir and disperse, then add stannous octoate toluene solution with a concentration of 0.2 mol / L thereto, stir and mix evenly, heat up to 65 °C, remove toluene by vacuum distillation, fill the flask with nitrogen, evacuate and repeat three times, seal the flask, and place it in a vacuum oven at 170 °C for melt ring-opening polymerization reaction for 5 h. After the reaction is completed, add dichloromethane thereto, filter by suction, wash with ethanol, and dry to obtain the modified polylactic acid drug-loading material.

[0039] (5) Add 2 g of chlorpyrifos and 6 g of the modified polylactic acid drug-loading material into dichloromethane solvent, stir and dissolve, then add an aqueous solution of polyvinyl alcohol-gelatin with a mass fraction of 1.5% thereto, disperse and emulsify with a high-speed internal cutting disperser for 4 min, continuously stir at a constant speed of 400 r / min for 4 h, filter by suction, wash with deionized water, and dry to obtain the chlorpyrifos-modified polylactic acid material.

[0040] Example 3

[0041] (1) Add 10 g of lignin into deionized water, adjust the pH to 10 with 10% sodium hydroxide aqueous solution, heat up to 90 °C, add 5 g of aminated mesoporous silica and 37% formaldehyde aqueous solution thereto, stir and react for 2 h. After the reaction is completed, wash successively with dilute hydrochloric acid and deionized water, and dry to obtain mesoporous silica modified lignin.

[0042] (2) Add 1 g of graphene oxide into deionized water, disperse by ultrasonic wave, then add 40 g of sodium hydroxide and 50 g of vinyl chloride thereto, stir and disperse, react by ultrasonic wave for 2 h, wash by centrifugation with dilute hydrochloric acid, and dry to obtain vinylated graphene oxide.

[0043] (3) Under a nitrogen atmosphere, add 4 g of diethanolamine into ethanol solvent, stir and disperse, then add 4 g of vinylated graphene oxide thereto, heat up to 70 °C, stir and react for 12 h. After the reaction is completed, distill under reduced pressure, wash with deionized water, and dry to obtain graphene oxide diol.

[0044] (4) Add 3 g of graphene oxide diol, 3 g of mesoporous silica modified lignin, and 10 g of L-lactide into a flask, stir and disperse, then add stannous octoate toluene solution with a concentration of 0.1 mol / L thereto, stir and mix evenly, heat up to 70 °C, remove toluene by vacuum distillation, fill the flask with nitrogen, evacuate and repeat three times, seal the flask, and place it in a vacuum oven at 175 °C for melt ring-opening polymerization reaction for 5 h. After the reaction is completed, add dichloromethane thereto, filter by suction, wash with ethanol, and dry to obtain the modified polylactic acid drug-loading material.

[0045] (5) Add 2 g of chlorpyrifos and 8 g of the modified polylactic acid drug-loading material to dichloromethane solvent, stir to dissolve, then add an aqueous solution of polyvinyl alcohol-gelatin with a mass fraction of 1.5%, disperse and emulsify with a high-speed internal cutting disperser for 2 min, stir continuously at a constant speed of 400 r / min for 5 h, filter by suction, wash with deionized water, and dry to obtain the chlorpyrifos-modified polylactic acid material.

[0046] Example 4

[0047] (1) Add 10 g of lignin to deionized water, adjust the pH to 11 with a 10% aqueous sodium hydroxide solution, heat up to 90 °C, add 8 g of amino-functionalized mesoporous silica and an aqueous formaldehyde solution with a mass fraction of 37%, stir and react for 4 h. After the reaction, wash successively with dilute hydrochloric acid and deionized water, and dry to obtain the mesoporous silica-modified lignin.

[0048] (2) Add 1 g of graphene oxide to deionized water, ultrasonically disperse, then add 45 g of sodium hydroxide and 25 g of vinyl chloride, stir and disperse, ultrasonically react for 4 h, wash by centrifugation with dilute hydrochloric acid, and dry to obtain the alkenylated graphene oxide.

[0049] (3) Under a nitrogen atmosphere, add 6 g of diethanolamine to ethanol solvent, stir and disperse, then add 4 g of the alkenylated graphene oxide, heat up to 50 °C, stir and react for 20 h. After the reaction, distill under reduced pressure, wash with deionized water, and dry to obtain the graphene oxide-containing diol.

[0050] (4) Add 4 g of the graphene oxide-containing diol, 4 g of the mesoporous silica-modified lignin, and 10 g of L-lactide to a flask, stir and disperse, then add a stannous octoate toluene solution with a concentration of 0.2 mol / L, stir and mix evenly, heat up to 65 °C, vacuum distill to remove toluene, fill the flask with nitrogen and evacuate it repeatedly three times, seal the flask, and place it in a vacuum oven at 175 °C for melt ring-opening polymerization reaction for 5 h. After the reaction, add dichloromethane for suction filtration, wash with ethanol, and dry to obtain the modified polylactic acid drug-loading material.

[0051] (5) Add 2 g of chlorpyrifos and 9 g of the modified polylactic acid drug-loading material to dichloromethane solvent, stir to dissolve, then add an aqueous solution of polyvinyl alcohol-gelatin with a mass fraction of 1.5%, disperse and emulsify with a high-speed internal cutting disperser for 4 min, stir continuously at a constant speed of 400 r / min for 3 h, filter by suction, wash with deionized water, and dry to obtain the chlorpyrifos-modified polylactic acid material.

[0052] Example 5

[0053] (1) Add 10 g of lignin to deionized water, adjust the pH to 11 using a 10% aqueous sodium hydroxide solution, heat up to 95 °C, add 6 g of aminated mesoporous silica and an aqueous formaldehyde solution with a mass fraction of 37% thereto, stir and react for 5 h. After the reaction, wash successively with dilute hydrochloric acid and deionized water, and dry to obtain mesoporous silica-modified lignin.

[0054] (2) Add 1 g of graphene oxide to deionized water, ultrasonically disperse it, then add 55 g of sodium hydroxide and 40 g of vinyl chloride thereto, stir and disperse, ultrasonically react for 3 h, wash by centrifugation with dilute hydrochloric acid, and dry to obtain alkenylated graphene oxide.

[0055] (3) Under a nitrogen atmosphere, add 2 g of diethanolamine to an ethanol solvent, stir and disperse it, then add 4 g of alkenylated graphene oxide thereto, heat up to 60 °C, stir and react for 24 h. After the reaction, perform vacuum distillation, wash with deionized water, and dry to obtain graphene oxide-containing diol.

[0056] (4) Add 5 g of graphene oxide-containing diol, 5 g of mesoporous silica-modified lignin, and 10 g of L-lactide to a flask, stir and disperse them, then add a stannous octoate toluene solution with a concentration of 0.15 mol / L thereto, stir and mix evenly, heat up to 70 °C, remove toluene by vacuum distillation, fill the flask with nitrogen and evacuate it repeatedly three times, seal the flask, and place it in a vacuum oven at 175 °C for melt ring-opening polymerization reaction for 5 h. After the reaction, add dichloromethane thereto, perform suction filtration, wash with ethanol, and dry to obtain a modified polylactic acid drug-loading material.

[0057] (5) Add 2 g of chlorpyrifos and 10 g of the modified polylactic acid drug-loading material to a dichloromethane solvent, stir to dissolve, then add a polyvinyl alcohol-gelatin aqueous solution with a mass fraction of 1.5% thereto, disperse and emulsify it using a high-speed internal cutting type disperser for 3 min, continuously stir at a constant speed of 400 r / min for 4 h, perform suction filtration, wash with deionized water, and dry to obtain a chlorpyrifos-modified polylactic acid material.

[0058] Comparative Example 1

[0059] The difference between this comparative example and Example 1 is that in step (5), polylactic acid is used instead of the modified polylactic acid drug-loading material.

[0060] Determine the drug loading and encapsulation efficiency of the microspheres by HPLC. The detection conditions are as follows: Amethyst C18-H chromatographic column (4.6 mm × 250 mm), ultraviolet detector, column temperature is room temperature 25 °C, flow rate is 1 mL / min, detection wavelength is 289 nm, injection volume is 20 μL, and the mobile phase is a methanol aqueous solution with a concentration of 90%.

[0061] Actual drug loading (%) = (mass of chlorpyrifos in microspheres / total mass of microspheres) × 100%;

[0062] Theoretical drug loading (%) = (mass of chlorpyrifos actually input / mass of chlorpyrifos actually input + mass of modified polylactic acid material actually input) × 100%;

[0063] Entrapment efficiency (%) = (actual drug loading / theoretical drug loading) × 100%.

[0064] Table 1:

[0065] Entrapment efficiency (%) Example 1 86.7 Example 2 92.4 Example 3 95.5 Example 4 94.3 Example 5 92.0 Comparative Example 1 73.8

[0066] As can be seen from the table, the material prepared by the present invention has a good entrapment efficiency for chlorpyrifos.

[0067] Place 1 g of chlorpyrifos-modified polylactic acid material in a dialysis bag, soak it in 100 mL of deionized water, shake it in a constant temperature water bath oscillator at 25 °C, take a 2 mL sample every t days, measure the concentration of chlorpyrifos using HPLC, and then add 2 mL of fresh distilled water to completely replace the soaking solution. The cumulative release amount (%) = (concentration of chlorpyrifos in the sustained release medium after t days / concentration of chlorpyrifos after complete release) × 100%.

[0068] Table 2:

[0069]

[0070] As can be seen from the table, the modified polylactic acid drug-loaded material prepared by the present invention has a good sustained release effect.

[0071] The technical solutions of the above embodiments are the preferred embodiments of the present invention. Without departing from the principle of the present invention, several improvements and transformations can be made, and these improvements and changes should also be regarded as within the protection scope of the present invention.

Claims

1. Preparation of a modified polylactic acid drug-loading material, characterized in that, The preparation is as follows: Add graphene oxide diol, mesoporous silica modified lignin, and L-lactide into a flask, stir and disperse them, then add stannous octoate toluene solution with a concentration of 0.1 - 0.2 mol / L, stir and mix evenly, heat up to 65 - 75 °C, remove toluene by vacuum distillation, fill the flask with nitrogen, evacuate and repeat three times, seal the flask, and place it in a vacuum oven at 150 - 175 °C for melt ring-opening polymerization reaction for 3 - 6 h. After the reaction, add dichloromethane for filtration, wash with ethanol, and dry to obtain the modified polylactic acid drug-loading material; The preparation method of the mesoporous silica modified lignin is as follows: Add lignin into deionized water, adjust the pH to 10 - 11 with 10% sodium hydroxide aqueous solution, heat up to 85 - 95 °C, add amino-functionalized mesoporous silica and 37% formaldehyde aqueous solution, stir and react for 2 - 5 h. After the reaction, wash with dilute hydrochloric acid and deionized water in sequence, and dry to obtain the mesoporous silica modified lignin; The preparation method of the graphene oxide diol is as follows: (1) Add graphene oxide into deionized water, disperse it by ultrasonic wave, then add sodium hydroxide and vinyl chloride, stir and disperse, react by ultrasonic wave for 2 - 4 h, wash by centrifugation with dilute hydrochloric acid, and dry to obtain vinylated graphene oxide; (2) Under a nitrogen atmosphere, add diethanolamine into ethanol solvent, stir and disperse, then add vinylated graphene oxide, heat up to 50 - 70 °C, stir and react for 12 - 24 h. After the reaction, distill under reduced pressure, wash with deionized water, and dry to obtain graphene oxide diol.

2. Preparation of the modified polylactic acid drug-loading material according to claim 1, characterized in that, The mass ratio of the graphene oxide diol, mesoporous silica modified lignin, and L-lactide is 0.1 - 0.5:0.1 - 0.5:

1.

3. Preparation of the modified polylactic acid drug-loading material according to claim 1, characterized in that, The mass ratio of the lignin and amino-functionalized mesoporous silica is 1:0.5 - 1.

4. Preparation of the modified polylactic acid drug-loading material according to claim 1, characterized in that, In the above (1), the mass ratio of the graphene oxide, sodium hydroxide, and vinyl chloride is 1:40 - 55:25 - 50.

5. The preparation of the modified polylactic acid drug-loading material according to claim 1, characterized in that, In the above (2), the mass ratio of the diethanolamine and vinylated graphene oxide is 0.5 - 1.5:

1.

6. Use of a modified polylactic acid drug-loaded material prepared by the preparation method according to claims 1-5 in a pesticide formulation, characterized in that: Add chlorpyrifos and the modified polylactic acid drug-loading material into dichloromethane solvent, where the mass ratio of chlorpyrifos to the modified polylactic acid drug-loading material is 1:2 - 5, stir to dissolve, then add 1.5% polyvinyl alcohol-gelatin aqueous solution, disperse and emulsify with a high-speed internal cutting disperser for 2 - 4 min, stir continuously at a constant speed of 400 r / min for 3 - 5 h, filter, wash with deionized water, and dry to obtain the chlorpyrifos-modified polylactic acid material.

Images