Abstract: Chitosan hollow microcapsules,used as pesticide-loading carrier,were fabricated by self-assembly and sacrificial template method. Polystyrene,as the template,was first prepared through dispersion polymerization and sulfonated with H₂SO₄ afterward. Then the chitosan was employed to assembly onto the surface of sulfonated polystyrene electronically and cross linked it with glutaraldehyde so as to form the steady core-shell microspheres. Next,the tetrahydrofuran was applied to the removal of template and the cross-linked chitosan hollow microcapsules were successfully fabricated. To characterize the molecular weight,particle size and the size distribution of polystyrene microsphere,gel permeation chromatography and nano-particle size analyzer were used. Moreover,properties of the core-shell structure microspheres were confirmed by the zeta potentiometer,the scanning electron microscopy,the transmission electron microscopy,and the thermogravimetric analyzer. The model pesticide,imidacloprid,was then loaded on to the chitosan hollow microcapsule by way of passive absorption and permeation,and the release experiment was executed in methanol. Characteristic result from the fourier transform infrared spectrometer that was utilized to study the loading mechanism confirmed the hollow microcapsules interacted on imidacloprid with hydrogen bonding,which resulted in an extended releasing time. The result showed that the pesticide loading capacity of chitosan hollow microcapsules reached 31.78%. The initial burst release presented 56.63% of release rate. The loaded microcapsules maintained a certain amount of release,which demonstrated that the loading site of chitosan microcapsules was mainly on the surface and the pesticide staying inside the microcapsule wouldn't come out until the degradation of the microcapsules,which meant the loaded microcapsules had achieved the expected sustained-release effect.

Key words: electrostatic self-assembly, size distribution, chitosan, polyelectrolyte, microcapsules, permeation, imidacloprid

摘要： 采用目前材料领域新型的自组装模板法制备了壳聚糖空心微胶囊。首先使用分散聚合的方法合成了粒径均一的聚苯乙烯微球，粒径范围在1~2μm。然后用H₂SO₄将聚苯乙烯表面功能化为磺化聚苯乙烯，并以之为模板，将壳聚糖静电组装于其表面，经戊二醛交联后用四氢呋喃溶解模板，成功制备出生物相容和可降解的交联壳聚糖空心微胶囊。研究采用凝胶渗透色谱和纳米粒度仪测试合成聚苯乙烯微球的分子量、粒径及粒度分布等性能；利用Zeta电位仪、扫描电镜、透射电镜和热重分析仪对核-壳结构与空心微胶囊的特性进行表征。以吡虫啉为模型药物，通过吸附与渗透的方式负载到壳聚糖交联空心微胶囊，在甲醇下进行缓释实验。傅里叶转换红外光谱仪的表征证明氢键力在壳聚糖对吡虫啉的负载起到了重要作用。释放实验的结果表明，壳聚糖空心微胶囊对吡虫啉的载药量达到31.78%，前期出现的释放量达56.63%，释放实验后期能保持一定的缓慢释放量，表明壳聚糖空心微胶囊的载药部位主要在其表面与内部，而进入微胶囊内部的药物则需要在交联壳聚糖降解后缓慢释出，达到所期望的缓释效果。

关键词: 静电自组装, 粒度分布, 壳聚糖, 聚电解质, 微胶囊, 渗透, 吡虫啉