两亲性海藻酸衍生物与SiO2纳米颗粒协同稳定载药乳液的机制及对农药在热带土壤中环境行为的影响

A stable and environmentally friendly Pickering emulsion pesticides-loaded will be obtained through the research of the molecular design of natural macromolecules, the interaction between macromolecules and nanoparticles, as well as the formation mechanism and environmental behavior of stable emulsion. Based on developing sodium alginate resource obtained from Sargassum algae in Hainan coastal waters, different molecular weight sodium alginates will be hydrophobicly modified to synthesized amphiphilic sodium alginate derivatives（ASAD） by Ugi reaction and will be used as macromolecular surfactant. The aggregation behaviors Of ASAD in water solution, such as molecular configuration and rheology, will be investigated in detail. And the adsorption of ASAD on surface of nanoparticle silicon dioxide(SiO2 ) and interface of SiO2/water will be studied also.. The influence of ASAD and SiO2 synergistic effects on stability of cyhalothrin-loaded oil-in-water(O/W) pickering emulsion will be tested. These studies will indicate the mechanism of adsorption of the ASAD on surface of nanoparticle silicon dioxide(SiO2) and interface of SiO2/water . And the mechanism of this pickering emulsion stabilized by synergistic effects of ASAD and SiO2 will be elucidated,either.. Furthermore, the influence of ASAD on the adsorption/ desorption process of cyhalothrin/drug in tropical soil will be tested in order to discover environmental behavior of this pickering emulsion. Reducing environmental polution of pesticides/drug as possible through using the green macromolecular surfactants is always expected.These results will provide guide for optimizing its formulation and preparing stabilized environmental friendliness O/W drug-loaded pickering emulsion .. This research will enrich the theory system and application development of macromolecular surfactant on nanoparticle dispersion and stability, and will also establish scientific basis for developing some new environmentally friendly pesticide formulation.And this research possesses important scientific and practical significance in the ecological environment protect and the control of pesticides on soil environment pollution from the origin.

通过天然大分子的分子设计、大分子与纳米颗粒相互作用、载药乳液稳定机制及环境行为的研究，获得稳定、与环境友好的载有农药的Pickering乳液。本项目以前期研究获得的不同分子量海藻酸钠，进行Ugi反应疏水改性制备两亲性海藻酸衍生物（ASAD），研究ASAD在纳米颗粒SiO2/水和界面的吸附特征；并以氯氟氰菊酯为模型药物，研究ASAD与SiO2纳米颗粒协同作用对载药O/W型Pickering乳液稳定性的影响，揭示ASAD在纳米颗粒表面的吸附特征及协同稳定Pickering 乳液的机制。为探明乳液的环境行为，进而研究两亲性海藻酸衍生物对所载药物在热带土壤中的吸/脱附过程的影响，期望通过绿色表面活性剂的作用减少农药对环境的污染，实现乳液的绿色化及功能化。研究结果可丰富高分子表面活性剂对纳米颗粒的分散稳定作用的理论及应用研究，同时为从源头上控制农药对土壤环境的污染及环保型农药创制技术提供科学依据。

通过对两亲性海藻衍生物的分子设计、两亲性海藻衍生物与SiO2纳米颗粒相互作用、载药乳液稳定机制及环境行为的研究，获得稳定、与环境友好的载有农药的Pickering乳液。研究结果不仅丰富了高分子表面活性剂对纳米颗粒的分散稳定作用的理论及应用研究，同时为从源头上控制农药对土壤环境的污染及环保型农药创制技术提供了科学依据。.首先通过Ugi四组分缩合反应合成了两亲性海藻酸钠衍生物。通过不同分子量Ugi-Alg在SiO2颗粒表面的吸附得到了具有不同稳定性的分散体系。结果表明，高分子量H-Ugi-Alg 与SiO2之间存在氢键更强，可以使Ugi-Alg更紧密地吸附到颗粒表面，且浓度在CAC值附近使悬浮液具有较好的分散稳定效果，通过静电位阻效应促进了体系的稳定性。.其次，进一步探究了Ugi-Alg/SiO2大分子颗粒乳化剂对Pickering乳液性能的影响及稳定机理。结果表明，Ugi-Alg与SiO2之间具有协同效应，颗粒浓度为2 wt%的H-Ugi-Alg (Mw=685508)体系具有最好的稳定性和黏弹性，且可以通过控制颗粒浓度、Ugi-Alg分子量以及pH对Pickering乳液的稳定性进行调控。H-Ugi-Alg和SiO2之间较强的相互作用以及Ugi-Alg起到的桥接作用，能够提高乳液中三维网状结构的刚性，有利于提高乳液的稳定性。.进一步研究了载有农药药物的O/W 型Pickering乳液在土壤中环境行为。结果表明，高分子量改性海藻酸钠（Ugi-alginate-H）更有利于农药在土壤上的吸附。经探究Langmuir和Freundlich模型都适合模拟啶虫脒在土壤上的吸附等温线。随着Ugi-alginate分子量的增加，Kd值增加，农药在土壤上的吸附能力增强。这是由于改性海藻酸钠不仅会与农药分子之间形成氢键及具有疏水相互作用，还可能通过与钙离子桥联的方式增加农药在土壤上的吸附量。