Abstract:

To reduce the environmental pollution caused by pesticides and improve the effective application of the hydrophobic pesticide avermectin (AVM) in crops, castor oil-based waterborne polyurethane emulsion (CP) synthesized by self-emulsification method was coated AVM to obtain the drug-loaded emulsion (CPA). The chemical structure, microstructure, thermal stability, contact angle, leaf retention, ultraviolet resistance, sustained release performance, insecticidal activity and storage stability of drug-loaded emulsions with different castor oil (CO) contents were studied. The results showed that compared with AVM dispersion, the contact angle of CPA on cucumber leaves decreased by more than 20% and the retention increased by more than 50%, which indicated that CPA had better affinity and wettability on cucumber leaves. Under the same UV irradiation, the half-life of CPA was nearly half longer than AVM dispersion, indicating that CPA had good ultraviolet resistance. The drug loading rate of CPA was between 5.61% and 6.62% and the encapsulation efficiency was more than 70%. It had good sustained release performance. The drug release behavior conformed to the First-order kinetic model and was controlled by Fickian diffusion. There was no significant difference between CPA and AVM dispersion in the insecticidal activity against plutella xylostella.

Key words: castor oil, waterborne polyurethane, sustained release, emulsions, support, stability

摘要：

为减少农药在使用过程中对环境造成的污染，提高疏水性农药阿维菌素（AVM）在作物中的有效应用，通过自乳化法合成了蓖麻油基水性聚氨酯乳液（CP）用于包覆AVM得到载药乳液（CPA），研究了不同蓖麻油（CO）含量载药乳液的化学结构、微观结构、热稳定性、接触角、叶面滞留量、抗紫外性能、缓释性能、杀虫活性和储存稳定性。结果表明，相比AVM分散液，CPA在黄瓜叶面上的接触角降低了20%以上，滞留量提高了50%以上，说明其在叶面上有较好的亲和力和润湿性；相同紫外强度照射下，CPA的半衰期相较AVM分散液延长了近一半，说明CPA具有良好的抗紫外性能；CPA的载药率在5.61%~6.62%之间，包封率可达70%以上，并具有良好的缓释性能，释药行为符合First-order动力学模型，药物释放受Fickian扩散控制，且CPA与AVM分散液对小菜蛾的杀虫活性无显著差异。

关键词: 蓖麻油, 水性聚氨酯, 缓释, 乳液, 载体, 稳定性