Preparation and properties of castor oil-based waterborne polyurethane drug-loaded emulsion
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.
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