| Lignin resources are abundant,and have the advantages of natural regeneration,green environmental protection and so on.In recent years,more and more studies have focused on the application of industrial lignin as a polymer material in the field of chemical materials.Lignin is a natural polymer,which contains a large number of hydrophobic structural units of phenylpropane,which has good compatibility with non polar pesticides.It can be used as a pesticide carrier material;lignin has a rich hydroxy group and carboxyl group and other hydrophilic groups.Alkyl acylation can increase the compatibility with the hydrophobic substance and improve the application performance.In this study,the preparation conditions and formation mechanism of lignin/ high performance cyhalothrin nanospheres were studied systematically by using alkyl lignin as raw material and alkyl acylation to improve its hydrophobicity.Three kinds of acylated lignin were prepared by electrophilic substitution reaction with benzoyl chloride,caprylyl chloride and lauryl chloride respectively.Lignin was used as the carrier material to prepare the lignin/ high performance cyhalothrin nanospheres with a particle size less than 100 nm.The variety of solvent and surface active agent can regulate the diameter of lignin nanospheres in 40~2000 nm,and the greater the polarity of the solvent,the more the content of the benzene ring of the surfactant,the smaller the particle size of the nanospheres.The change of the dosage of lignin carrying material,surface active agent and the original drug can make the particle size of the nanospheres between 35~120 nm.The adsorption and embedding of surfactant on the surface of microspheres during the formation of drug loaded nanospheres can significantly improve the stability of nanospheres colloid.Based on the preparation conditions of lignin nanospheres,the formulation of high performance cyhalothrin nano preparation was optimized,and the sustained release performance and other properties of the high performance cyhalothrin nano preparation were studied.The study of sustained release performance showed that the time of releasing 50% and 80% active ingredients of Cyhalothrin nano preparation was 2.45~3.30 times of the ordinary microemulsion,the surface active agent could change the release rate,the slow release curve was approximately linear,and the fitting equation with the highest correlation was the first order kinetic equation.The dosage of lignin and the acylation mode have the control effect on the release rate of the high performance cyhalothrin nano preparation.The results show that the preparation has the best release property when the acylation mode chooses benzoylation and the dosage is 1%.In addition,the heat storage properties,acid and alkali resistance and adhesion properties of the lambda cyhalothrin nano preparations were studied.The mechanism research shows that the acylated lignin is entrapped with the original drug through the hydrophobic action of ?-? conjugation,and the carboxyl of lignin is enriched on the surface of the microsphere.The non ionic surfactants can be adsorbed on the surface of the microspheres steadily.The long chain of polyoxyethylene ether can increase the spatial steric resistance of the surface of the microspheres,thus reducing the size of the microspheres and improving the stability of the colloid solution of the nanospheres.In this study,lignin was used as the drug carrier to prepare the environmentally friendly nanoscale pesticide sustained-release preparation.The application of industrial lignin was extended to the field of nanoscale pesticide,which provided a new natural drug carrying material for the development of nanoscale pesticide in China. |
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