Gemini表面活性剂的设计合成及其在植物叶表面超润湿铺展作用机理研究

Using pesticide for crop diseases and insect pests controlling is an effective method of its high yield and good quality, study on the structure-activity relationship of superwetting agents and its superspreading mechanism is the key to urgently solving the problem of low efficiency for crop diseases and insect pests controlling. Basing on designing of molecule structures, siloxanes based gemini surfactants with different molecule structures will be synthesized through the microwave-assisted synthesis method, superwetting agents with superwettability will be obtained accordingly. Further more, the influence of molecule structures on the evolution of the molecular self-assembly structures will be studied and thermodynamic model in the evolution process will be further established.What's more, the relationship between molecule structures and its properties will be discussed and the structrue-properties will be revealled.And then aggregate structures in surfactant-laden liquid drop, the microstructures of surperwetting agents in or near three-phase interface of V/L/G will be studied, and superspreading dynamics behavior will be also studied. Moreover, relations of molecular structures on marangoni effect, autophilic spreading,and precursor film effect will be revealled. The model of superspreading behavior will be established or verified. A complexus superspreading theories will be proposed, Addtionally the superspreading regulation for dimehypo pesticide containing superwetting agent on the surface of plant leaves will be studied. This study is of great significance for promoting development of superspreading mechanism, improving the pesticide efficiency, reducing environment pollution and improving agricultural production efficiency.

农药防治农作物病虫草害, 是确保农业生产优质、高产、高效的重要手段，解决农作物防治中农药利用率低问题迫切需要对超润湿剂的构效关系及其超润湿铺展机理进行深入研究。从分子结构设计出发，通过微波法合成系列不同分子结构的三硅氧烷Gemini型具有超润湿特性的超润湿剂；研究分子结构对溶液自组装分子有序组合体形态演变的影响机制，建立其演变过程热力学理论模型，探讨形态演变与超润湿铺展性的关联，从而揭示分子结构与超润湿铺展的构效关系；探讨液滴内聚集体及气/液/固三相界面和附近处润湿剂分子的微观形貌，深入研究超润湿铺展行为和动力学，揭示分子结构对Marangoni效应、自亲效应和前驱液膜效应的影响规律，构建和验证超润湿铺展新模型，提出超润湿铺展复合驱动理论；并研究含超润湿剂的杀虫双药液在植物叶表面的超润湿铺展规律；本项目对完善超润湿铺展机理，提高药液利用率，减少环境污染，促进农业高效生产具有重要研究意义。

农药防治农作物病虫草害，是确保农业生产优质、高产、高效的重要手段，解决农作物防治中农药利用率低问题迫切需要对超润湿剂的构效关系及其超润湿铺展机理深入研究。本项目从分子结构设计出发，调控不同联接基团数m和乙氧基数n，合成得到系列不同分子结构的Gemini超润湿剂Sm(EO)n，通过红外、核磁证实成功合成了不同结构的Sm(EO)n，得到了转化率与反应因素的影响规律。反应动力学研究表明：丙烯酸与七甲基三硅氧烷的加氢反应均属二级反应，相对于常规法(109.272KJ/mol)，微波法(84.395KJ/mol)能够显著降低反应活化能，微波法具有非热效应和溶剂效应。胶团化热力学研究表明：Sm(EO)n 的最低临界表面张力低γcac至21mN/m，归结于含有伞状的七甲基三硅氧烷特殊结构。对比相同联接基（s=2、4或6)，不同EO数的Gemini表面活性剂(n=4.14、n=8.68、n=13.23)，研究发现：随着EO数增加，其HLB值显著增加，γcac增大，CAC增大，Amin增大，Гmax减少，△Gθmic和△Gθads呈现负值，且随着EO数增加，其胶束化能力和界面吸附能力减弱。对比相同EO数，不同联接基长度的超润湿剂，研究发现：随着联接基长度的增加，HLB值显著降低，γcac减小，CAC减小，Amin略增大，且△Gθmic和△Gθads略增大，说明更易形成胶束和吸附至气/液界面。TEM表明超润湿剂形成了尺寸为120nm到350nm的球型胶束，DLS表明：胶束大小随着疏水联接基团的增加而增加，随着亲水EO数的增加而减少。超润湿铺展动力学表明：润湿铺展分三个阶段，铺展半径和面积取决于联接链长度和乙氧基链长度。铺展半径、面积、最大铺展速率和平均铺展速率与联接链长度的关联性规律是呈线性单调性，与乙氧基链长度的关系呈现非单调性，n=8.68时为最大值；研究发现HLB值约为10的超润湿剂表现出最好润湿铺展行为。且CWC越低，Sm(EO)n 润湿铺展越好。铺展指数N大小表明铺展过程产生了Marangoni驱动，且铺展速率与分子结构和润湿基底有关。S6(EO)8.68在芒果叶上的平均铺展速率(0.084mm/s)比水稻叶(0.062mm/s)高。提出了前驱水膜和Marangoni效应是超润湿铺展主驱动力。S6(EO)8.68超润湿剂能显著提高杀虫双农药的铺展速率,铺展面积和药液利用率。