两性离子聚合物的合成及其在甜菜夜蛾无公害防治中的应用

The "3R" problems raised by the long term usage of chemical synthetic pesticide encouraged people to consider about the relationship between pesticides and harmonious ecological protection. It was noticed that the effective absorption of protein and cell on the plant surface is the fundament of the attachment, survival and reproduction of the phytophagous pests on plant surface. Thus a novel zwitterionic polymer (PMS-g-CB) based on polymethylsiloxane (PMS) backbone and carboxybetaine (CB) side chain was designed, synthesized and characterized, which was stable, non-toxic, super-hydrophilic, ultra-low protein and cell adsorption, and also non-obstructive to the communication between plant protein and environments. After PMS-g-CB was covered on the surface of cabbage (Brassica oleracea.var.capitata L.), the relationship among the oviposition, absorption and settlement of the eggs and larva of Spodoptera exigua on the surface of cabbage would be intensively studied. The aim of this project is to develop a novel obstructive and non-toxic polymer material (PMS-g-CB), after PMS-g-CB was insufflated on the surface of plant, a non-toxic micro-environment which was not suitable for the settlement of pest could be built, and by this way a hazard-free control of pest might be achieved. This research work would also supply a scientific fundament for the harmonious plant protection.

长期使用化学合成农药所带来的"3R"问题，促使人们思考化学农药与生态和谐之间的关系。蛋白和细胞在植物表面的有效吸附是植食性害虫生存繁衍的基础，本项目拟通过分子设计合成一种以聚硅氧烷（PMS）为主链、羧酸甜菜碱型两性分子（CB）为不可水解侧基的，具有超亲水性、抗蛋白和细胞吸附、不阻隔植物蛋白与外界作用的甜菜碱型两性离子聚合物（PMS-g-CB）新型材料，同时以世界性重要蔬菜害虫- - 甜菜夜蛾为对象，研究其成虫在喷洒不同结构PMS-g-CB材料的甘蓝叶片表面的产卵行为、卵块粘附和幼虫附着爬行行为及其与PMS-g-CB结构之间的关系。旨在研究开发一种新型的无毒聚合物材料，在蔬菜上喷洒后，能使其表面形成无毒、又不适应害虫附着的微生态环境，实现蔬菜害虫无公害防治目标，并为建立全新的和谐植保提供科学依据。

蛋白和细胞在植物表面的有效吸附是植食性害虫生存繁衍的基础，阻隔其在植物表面的吸附是植食性害虫无公害防治的新途径，其中的关键在于合成一类可在植物表面有效附着且具有极低聚合物-蛋白相互作用的聚合物。本项目在采用开环共聚反应合成一系列结构可控、分子量分布较窄的侧基含氢聚硅氧烷（PDMS-co-PHMS）的基础上，设计合成了一类以聚二甲基硅氧烷（PDMS）为主链、羧酸甜菜碱两性离子基团（CB）为侧基的、具有良好水溶性和生物相容性的聚硅氧烷接枝甜菜碱（PDMS-g-CB），在系统表征其在水相中的聚集特性和在固体表面吸附特性的基础上，从微观相互作用和宏观吸附/粘附两方面证实了PDMS-g-CB与蛋白和细菌之间仅存在极弱的相互作用，研究了PDMS-g-CB在植物叶片表面的吸附对其表面亲疏水性的影响特性；进一步将PDMS-g-CB的两性离子侧基更换为结构相似的季铵盐侧基，合成了一系列聚硅氧烷接枝季铵盐（PDMS-g-BC），与含季铵盐的均聚物相比，PDMS-g-BC因其具有更为疏水的PDMS主链，对于细菌和植物病原真菌（如：水稻纹枯病菌（R. Solani）和香蕉枯萎病菌（Foc4））有更强的抑制作用，并可通过调整聚合物主链的疏水性和侧基结构来调控其抑菌活性。