Preparation Of Chitosan Hollow Microcapsule And Study On Its Loading Properties Of Pesticide

In resent years,pesticide abuse has become a serious environmental problem.The pesticide residues and environmental pollution have threatened the health of human.Therefore,under the premise to ensure the efficacy of the pesticide,it’s necessary to study the micro dosing of pesticide,so as to strictly control its usage.For the sake of that,the pesticide microencapsulation is one of the most desirable approaches.Pesticide microencapsulation can be defined as using some kind of wall material to wrap the active ingredients of the pesticide,so that it can be released sustainably by infiltration and diffusion.As the candidate for the wall material of microcapsules,natural polymer material has gained the most popularity.Our study used imidachloprid as model drug and encapsulated it with chitosan to make the chitosan/imidachloprid microcapsule.The feasibility of imidacloprid microencapsulation and the drug loading mechanism have demonstrated that because of the distinctive molecular structure of chitosan,the hollow microcapsule loaded imidachloprid through hydrogen bonding interaction.The release experiments of the drug-loaded microcapsule showed that they existed a burst release in methanol medium,which would be an advantage for the efficacy of pesticide.The stable release rate of late release suggested that the model drug inside the microcapsule would not release in a short time,which indicated that the release mechanism of cross-linked chitosan was composed of drug diffusion and carrier degradation.Moreover,the preparation of chitosan hollow microcapsules was also explored.Our research found that sulfonation degree of the template sulfonated polystyrene increased with increasing sulfonation time,but when the sulfonation reached a proper time,we would observe a decrease in the hydrophilicity of the sulfonated polystyrene microspheres.What’s more,the removal of template in the core-shell microcapsule would leave –SO₃^- behind for the reason of its tight bonding with –NH₃⁺.This thesis has investigated the feasibility of cross-linked chitosan microcapsules for the loading of imidacloprid,by revealing the drug loading mechanism;it might provide a theoretical basis for the application of cross-linked chitosan hollow microcapsules in the field of drug loading.