Enhancing pesticide droplet deposition through O/W Pickering Emulsion: Synergistic stabilization by Flower-like ZnO particles and polymer emulsifier

The effective deposition of pesticide droplets on the plant leaves is an important challenge. In this study, flower-like ZnO particles were fabricated via a simple precipitation method at room temperature and were chosen as a stabilizer for Pickering emulsions. A 3% mefentrifluconazole Pickering emulsion with 70 vol% water phase fractions can be easily prepared using 0.5 wt% ZnO particles and 0.1 wt% A-7 as a dual emulsifier, thereby reducing the dosage of conventional surfactants. The simultaneous adsorption of ZnO particles and A-7 at the oil–water interface in the form of a densely packed layer exhibits synergistic effect, preventing droplet coalescence via a steric mechanism. The Pickering emulsion effectively inhibits the rebounding of droplets and deposits on rice leaves with different inclination angles in 1.5 ms, following which it spreads to the maximum wetting area within 360 s. In addition, the flower-like ZnO particles can be inlaid and adhered to various micro-nanostructures on the surface of a rice leaf. Owing to the topology effects between each other, it is beneficial for droplets to deposit on the leaf surface. The average control efficacy reached 90.37%, thereby improving the effective utilization of pesticides. This study provides a new opportunity for the application of flower-like ZnO particles as Pickering emulsion stabilizer in the agricultural field.