Study On New Pesticide Carrier Materials And Preparation And Properties Of Microcapsules

Microencapsulation technology has various advantages in pesticide formulation,such as improving physicochemical properties,increasing chemical stability,controlling release and prolonging the efficacy duration of pesticides,so it became a key means to improve pesticide utilization efficiency,decrease pesticide consumption,and solve pesticide pollution problem.In this paper,we chose the representative pesticides as a research model,and carried out the research of the following respects,in order to improve the utilization rate of pesticides and protect the ecological environment.1.In this paper,the modified isocyanate was used as the wall material to improve the method of preparing microcapsules by interfacial polymerization,in view of the defects of the traditional interfacial polymerization method,such as high toxicity,high reaction activity and difficult to control.The improved method has simple operation,mild reaction and low toxicity.The microcapsules of pirimiphos-methyl were prepared using the improved method,and the the influence of preparation conditions on the preparation process was discussed.The prepared microcapsules were characterized by SEM,CLSM,FTIR,TGA etc.The results showed that the prepared microcapsules had good appearance,uniform particle size distribution and good thermal stability.The average particle size was 2.05 μm.the encapsulation efficiency was 90.88%and the loading efficiency was 50%.The release kinetics study showed that the fit and release mechanism of different microcapsules prepared under different conditions was different with the existing model.The above results show that the improved interface polymerization method is suitable for the preparation of pesticide microcapsules,and the problem of smell and stability of pirimiphos-methyl were solved.2.The novel multifunctional seed coating agent of ZC was studied using carbosulfan and thiamethoxam as template agents,aiming at the single function problem of the traditional formulation of microcapsules.We prepared the carbosulfan microcapsules by the improved interfacial polymerization method,and the parameters in the preparation were also optimized.The microcapsules prepared after optimization had good appearance,uniform particle size distribution,the average partical size was 2.08 μm,the encapsulation efficiency was about 96.23%,the drug loading was about 50%,and the sustained release time was more than 50 days.The stability research showed that the microcapsule can improve the stability of carbosulfan,meanwhile,reduce the concentrate of carbofuran and the potential threat to the environment,improve the quality and safety of agricultural products,which is in the premise of ensuring the pesticide effect.The wheat germination rate and later growth activity experiments showed that compared with the EC,the carbosulfan microcapsules had no effect on germination and the growth of wheat.We prepared the thiamethoxam suspension concentrate using the conventional method and mixed with the carbosulfan microcapsules suspension to preparing the ZC seed coating agent.The effects on physical and chemical stability by the type and amount of thickener,pH value were studied in this paper.The pilot scale production of ZC seed coating agent was studied,which combined the theoretical research and practical application together.3.The preparation method of nano-microcapsules was studied using silica as a safety and environmental wall material.The cyhalothrin/SiO2 nanomicrocapsules were discussed and prepared,which had uniform particle size and high dispersibility.In order to control release,we modified the nano-microcapsules and prepeared double-layer microcapsules doped with organic and inorganic matericals,which were characterized by SEM、TEM、FTIR、TGA and showed good appearance and high thermal stability.Release kinetics study showed that the release rate of single microcapsules was lowered than double layer microcapsule under different pH value.The release rates of the two microcapsules were in accord with the Korsmeyer-Peppas equation,and the release mechanism was the combination of diffusion and dissolution.The bioactivity experiment of Musca domestica showed that the two kinds of microcapsules had good biological activity at 90th day.The above result showed that the microcapsules of SiO2 and SiO2-NIPAM-MBA had good release performance and the two environmentally friendly materials have great potential in development.4.The biodegradable acrylate-modified PLA-PEG-PLA block copolymer was prepared by modification using lactide and polyethylene glycol as raw materials.The prepared materials were characterized by NMR,FTIR and so on.The cypermethrin microcapsules were prepared by using the polymer as the wall material,which was characterized by FTIR,SEM and TGA.Release kinetics studies showed that the microcapsules have good sustained release performance,and the release mechanism is mainly based on diffusion and dissolution.This material provides reference for the research and development of biodegradable materials in agricultural fields.In this paper,the new preparation materials and methods were studied by adopting the combination of macroscopical and microcosmic methods,which provided reference for controlling release study of safe,environmentally friendly and multi-functional microcapsules.