高效氯氰菊酯微胶囊的制备、表征及释放性能

以高效氯氰菊酯为芯材, 乙基纤维素为壁材, 采用溶剂蒸发法制备了微胶囊, 并对其理化性能进行表征, 通过单因素实验研究了工艺参数对微胶囊外观形貌、 粒径大小及分布、 包封率、 载药量和缓释性能的影响. 结果表明, 乳化剂种类和剪切时间可以显著影响微胶囊的外观形貌; 随着乳化剂用量增大, 微胶囊粒径减小, 分布变窄, 当Tween-80用量从4%增加至8%时, 微胶囊平均粒径从59.9 μm减少到29.8 μm, 跨距也从1.21减少到0.72. 随着芯壁比(质量比)减小, 微胶囊粒径和包封率均逐渐增大, 载药量逐渐减小, 当芯壁比为1:1.75时, 包封率可以达到70%以上. 微胶囊释放动力学模型符合Ritger-Peppas模型(lgQ=lgk+nlgt); 平均粒径相近而载药量不同时, 初期载药量最小的样品释放速率慢, 累积释放率低; 载药量相近而平均粒径不同时, 粒径大的样品释放速率低, 累积释放率也低.

Preparation,Characterization and Release Properties of β-Cypermethrin Microcapsules†

The solvent evaporation method was adopted to prepare β-cypermethrin microcapsules, usingβ-cypermethrin as core material, ethylcellulose as wall materials. The physical and chemical properties of microcapsules were characterized. The effects of process conditions on appearance, mean particle size and distribution, encapsulation efficiency, loading content and controlled release were studied by single factor experiments. The results indicated that emulsifier types and shearing duration time had significant influence on appearance of microcapsules. The particle size and size distribution decreased with the increasing of emulsifier concentration. When the dosage of Tween-80 increased from 4% to 8%, the average particle size of microcapsules decreased from 59. 9 μm to 29. 8 μm, and the span reduced from 1. 21 to 0. 72. As the core-wall ratio decreased, there was a gradual increase in both particle size and encapsulation efficiency, but a de-crease in loading content. When the core-wall ratio was 1:1. 75, the encapsulation efficiency was more than 70%. The most fitted drug release kinetics model was the Ritger-Peppas model( lgQ=lgk+nlgt) . For microcap-sules with similar mean particle sizes and different loading content, the sample with minimum loading content tended to have a lower release rate and cumulative release rate. For microcapsules with similar loading content and diffe-rent mean particle sizes, the sample with largest size tended to have a lower release rate and cumula-tive release rate.