Development of Novel Urease-Responsive Pendimethalin Microcapsules Using Silica-IPTS-PEI As Controlled Release Carrier Materials

Microcapsules are highly desirable for attaining the most effective utilization of the pesticide as well as reducing environmental pollution. In this work, a novel urease-responsive system was prepared using isocyanate-functionalized silica cross-linked with polyethylenimine (silica IPTS PEI) via urea bonds. The results demonstrated that the silica IPTS PEI microcapsules had a high pendimethalin loading efficiency (approximately 30% w/w) and could effectively enhance the thermal and light stability of pendimethalin. The release curves agreed with the Ritger and Peppas equation, and the release of pendimethalin was diffusion-controlled. The release rates of synthesized silica-IPTS-PEI microcapsules showed positive correlation with the temperature. In weak acid and base conditions, the pendimethalin release rates were higher than under neutral conditions, and the silica IPTS PEI microcapsules displayed excellent urease-responsive property with controlled release performance. Compared with pendimethalin emulsifiable concentration, the silica-IPTS-PEI microcapsules had a longer duration and higher herbicidal activity against weeds in a greenhouse experiment. Allium cepa chromosome aberration assays showed that the microcapsules had lower genotoxicity than pendimethalin technical. Thus, the urease-responsive silica IPTS PEI microcapsules have a great potential application as an environmentally friendly herbicide formulation.