ATRP改性壳聚糖农药载体的设计及控制释放性能研究

控制释放技术是目前提高农药有效利用率、减少农药残留与环境污染问题的有效途径，其中载体材料的性能是关键。具有价廉、环境相容性好等众多优点的壳聚糖在农药控制释放研究中已表现出广阔的应用前景，但存在对脂溶性农药载药量低、释放可控性不强等局限性。本项目选用含典型官能团的烯烃单体，采用集自由基聚合与活性/可控聚合优点于一体的原子转移自由基聚合（ATRP）反应修饰改性壳聚糖，制备系列新型两亲性壳聚糖接枝共聚物。以吡唑醚菌酯为模式药物构建载药体系，进行载药量和释放动力学等研究，以期明确ATRP修饰改性壳聚糖微观化学结构与宏观载药量和可控释放性能之间的内在规律，为优化农药载体设计提供理论指导。本研究在国内外首次通过可控ATRP反应接枝不同疏水片段化学改性壳聚糖，改善其与脂溶性农药分子之间的相互作用，为提高农药载药量和构建释放时间与剂量符合实际防控需求的农药新剂型提供新的思路。

The technology of controlled release of pesticide provides a better solution for enhancing the efficiency of pesticide utilization and reducing the pesticide residue and environmental pollution. The performance of the carriers for controlled release pesticide formulation is crucial. Cheap and environmental friendly chitosan has great potential for development and application prospect in controlled release pesticide formulation research. However, when hydrophobic pesticides were loaded with chitosan and its derivatives as carriers, the loading content and release characteristics were not satisfactory. To the best of our knowledgement, chitosan derivatives chemically modified by controlled/living atom-transfer radical polymerization (ATRP) reaction as carriers for controlled release pesticide formulation has not been reported. In this project the novel amphiphilic chitosan copolymer was prepared by ATRP reactions and used as carriers for establishment of the pesticide-loaded microspheres with pyraclostrobin as model pesticide. Then the loading content and in vitro release kinetics of pyraclostrobin were studied and the inherent relationship between the microscopic chemical structure and macroscopic loading content and release profile was evaluated, which provide theoretical guidance for the optimization of formulation design. The pesticide loading content and release characteristics can be controlled by controllable ATRP reactions through the non-covalent bond interaction between the hydrophobic segment of chitosan copolymer and hydrophobic pesticide. The implement of this project will provide new idea to improve the loading content and fabricate novel pesticide formulations which release the active ingredient consistent with the practical demand.