Controlled Release of Insecticides throμgh Polyurea Microcapsules Synthesized by Interfacial Polycondensation

摘要

Among the various objectives of microencapsulation, controlled release of an active ingredient is perhaps the most engaging and challenging. Interfacial polycondensation is one of the most effective techniques for the synthesis of microcapsules loaded with an active ingredient. Here, chlorpyriphos, cypermethrin and pretilachlor have been encapsulated in polyurea shells synthesized via interfacial polycondensation under various preparative conditions and their release rates into methanol at 28-30 °C. The effect of initial monomer mole ratio, temperature, and the number of moles of limiting reactant (during synthesis of microcapsules by interfacial polycondensation) is discussed in terms of the properties of the shell, which ultimately controls the release rate. Semi-crystalline polyurea was synthesized which was characterized by Fourier transform infrared spectrophotometer, powder X-ray analysis and differential scanning calorimeter. The encapsulation efficiency of various insecticides increases with a decrease in initial monomer mole ratio and decrease in moles of limiting reactant.