谷胱甘肽响应性农药微胶囊的制备及性能研究

【作者】 王荣；

【导师】 任天瑞；

【作者基本信息】 上海师范大学 ， 高分子化学与物理， 2022， 硕士

【摘要】 农药在使用过程中存在利用率低,持效期短,环境安全性低等问题。同时,近年来国家对环保的提倡,对农药制剂行业也提出了新要求。开发绿色、安全、高效的农药制剂势在必行。智能响应性农药控释剂具有可控精准释放、提高药效、降低施药次数、减少环境污染等优点,被人们广泛研究。本论文以聚氨酯为微胶囊囊壁材料,吡唑醚菌酯为模型农药,2-羟乙基二硫醚为扩链剂,通过界面聚合法,制备了谷胱甘肽响应的聚氨酯微胶囊。利用单因素和多因素正交实验对合成条件进行了优化。同时对微胶囊形貌、粒径分布等物理化学性能、控释性能、抗光解性能及生物活性测试进行了探究,得到以下结论:（1）微胶囊制备实验:通过单因素实验对乳液制备过程中最优溶剂和乳化剂种类进行了筛选,结合乳液形貌及粒径分析,确定乙酸丁酯作为溶剂、EL-40作为最优乳化剂。同时,通过正交实验设计,以微胶囊粒径、包封率作为评价指标,探究溶剂用量、乳化剂用量、扩链温度、芯壁比对微胶囊的影响,确定了最优工艺配方为溶剂用量12g、乳化剂用量8g、扩链温度为60℃、芯壁比为1:2,合成了粒径分布均匀,大小为480 nm的微胶囊。并通过对微胶囊扫描电镜、红外、、元素分析、热分析表征确定了聚氨酯微胶囊的合成。（2）吡唑醚菌酯控释实验:选用吡唑醚菌酯作为缓释模型药剂,通过不同浓度的谷胱甘肽（0 m M,1 m M,2 m M,3 m M,4 m M）对微胶囊释放性能的研究发现,随着谷胱甘肽浓度的增大,吡唑醚菌酯缓释越快,累积释放率越高。当谷胱甘肽浓度为0 m M时,吡唑醚菌酯累积释放率为61%。而当谷胱甘肽为4 m M时,累积释放率为94%,该结果表明该微胶囊具有谷胱甘肽响应性,这也证明了含二硫键微胶囊的成功制备。对微胶囊的缓释动力学模型拟合结果发现,该微胶囊制剂释放机制符合Ficker扩散。（3）润湿性能测定实验:通过测定药剂在靶标作物（小麦）上的接触角和表面张力,发现药剂的表面张力未稀释时为30.8 m N/m,药剂在小麦叶片上的接触角为32°,远小于90°,表明该微胶囊制剂有良好的润湿性能,这将有利于提高农药液滴的在靶标作物的保留能力,提高农药利用率。（4）制剂稳定性能测试实验:通过对微胶囊热贮、常贮流变性能的研究,发现该微胶囊显示出剪切变稀的流变特性,并对其触变性研究,发现其常温下结构回复率为97.88%,热储之后结构回复率为96.4%,确定该微囊具有良好的悬浮稳定性及热稳定性。（5）生物活性测试实验:选用禾谷镰孢菌为抑菌实验对象,采用生长速率法,对实验对象进行处理,评价载吡唑醚菌酯聚氨酯微胶囊的杀菌性能及其谷胱甘肽响应性。抑菌实验结果表明,该微胶囊自身具有良好的抑菌性能,其EC₅₀值为23.4μL/L。当在有2 m M谷胱甘肽存在的情况下,其EC₅₀值为13.5μL/L,微胶囊的抗菌性能更优。表明该微胶囊有良好的谷胱甘肽响应性。（6）抗光解性能测试实验:通过比较单独的吡唑醚菌酯原药和载吡唑醚菌酯聚氨酯微胶囊制剂在274 nm下的光解实验,发现在30 h内微胶囊制剂中的吡唑醚菌酯光解速度明显低于单独的吡唑醚菌酯原药本身,有效提高了吡唑醚菌酯的抗光解性能。更多还原

【Abstract】 In the process of using pesticides,there are problems such as low utilization rate,short duration of validity and low environmental safety.At the same time,the country’s promotion of environmental protection in recent years has also put forward new requirements for the pesticide formulation industry.It is imperative to develop green,safe and efficient pesticide formulations.Intelligent responsive pesticide controlled-release agents have the advantages of controllable and precise release,improved efficacy,reduced application times,and reduced environmental pollution,and have been widely studied.In this paper,glutathione-responsive polyurethane microcapsules were prepared by interfacial polymerization with polyurethane as the microcapsule wall material,pyraclostrobin as the model pesticide,and 2-hydroxyethyl disulfide as the chain extender.The synthesis conditions were optimized using single-factor and multi-factor orthogonal experiments.At the same time,the physical and chemical properties,controlled release properties and biological activity tests of microcapsules such as morphology,particle size distribution were explored,and the following conclusions were obtained:（1）Microcapsule preparation experiment:The optimal solvent and emulsifier types in the emulsion preparation process were screened by single factor experiment,combined with the analysis of emulsion morphology and particle size,it was determined that butyl acetate was used as the solvent and EL-40 was the optimal solution.emulsifier.At the same time,through orthogonal experimental design,using the microcapsule particle size and encapsulation efficiency as evaluation indicators,the effects of solvent dosage,emulsifier dosage,chain extension temperature,and core-to-wall ratio on microcapsules were explored,and the optimal process formula was determined as solvent The dosage of 12g,the dosage of emulsifier was 8g,the chain extension temperature was 60℃,and the ratio of core to wall was 1:2.The microcapsules with uniform particle size distribution and size of 480 nm were synthesized.The synthesis of polyurethane microcapsules was confirmed by characterization of microcapsules by scanning electron microscope,infrared and thermal analysis.（2）Pyraclostrobin controlled-release experiment:Pyraclostrobin was selected as the sustained-release model agent,and the microparticles were treated with different concentrations of glutathione（0 m M,1 m M,2 m M,3 m M,4 m M）.The research on the release properties of capsules found that with the increase of glutathione concentration,the faster the sustained release of pyraclostrobin,the higher the cumulative release rate.When the glutathione concentration was 0 m M,the cumulative release rate of pyraclostrobin was 61%.When the glutathione was 4 m M,the cumulative release rate was 94%,which indicated that the microcapsules were responsive to glutathione,which also proved the successful preparation of the disulfide bond-containing microcapsules.The fitting results of the sustained-release kinetic model of the microcapsules showed that the release mechanism of the microcapsule formulations conformed to Ficker diffusion.（3）Wetting performance measurement experiment:By measuring the contact angle and surface tension of the agent on the target crop（wheat）,it was found that the surface tension of the agent was 30.8 m N/m when undiluted,and the contact angle of the agent on wheat leaves was 32.°,far less than 90°,indicating that the microcapsule preparation has good wetting performance,which will help to improve the retention ability of pesticide droplets in target crops and improve the utilization rate of pesticides.（4）Preparation stability test experiment:Through the research on the rheological properties of microcapsules in thermal storage and normal storage,it is found that the microcapsules show shear-thinning rheological properties,and the thixotropy of the microcapsules is studied.The structure recovery rate was 97.88%,and the structure recovery rate after thermal storage was 96.4%,confirming that the microcapsules had good suspension stability and thermal stability.（5）Biological activity test experiment:Fusarium graminearum was selected as the antibacterial experimental object,and the experimental object was treated by the growth rate method to evaluate the bactericidal performance of pyraclostrobin-loaded polyurethane microcapsules and its glutathione Responsiveness.The results of antibacterial experiments showed that the microcapsules themselves had good antibacterial properties,and the EC₅₀ value was 23.4μL/L.When in the presence of 2m M glutathione,its EC₅₀ value was 13.5μL/L,and the antibacterial properties of the microcapsules were better.It shows that the microcapsules have good glutathione responsiveness.（6）Test experiment of anti-photolysis performance:By comparing the photolysis experiments of the original pyraclostrobin original drug and the pyraclostrobin-loaded polyurethane microcapsule preparation at 274 nm,it was found that within 30 hours,the pyraclostrobin preparation in the The photolysis speed of pyraclostrobin was significantly lower than that of the original pyraclostrobin itself,which effectively improved the photolysis resistance of pyraclostrobin.更多还原