Preparation and characterization of water-in-oil emulsions of isoprothiolane

Rice blast is a serious disease affecting rice, which causes considerable reduction to its yield. Chemical control plays an important role in controlling this disease. Agricultural aerial spraying is one of the most efficient methods for plant protection over large areas, especially in paddy fields. However, formulations suitable for application by unmanned aerial vehicles (UAVs) are lacking in China. Based on the requirements of aerial spraying special formulations, the solvent and emulsifier were screened to prepare water-in-oil (EO) emulsions of isoprothiolane, and the stabilities of the resulting emulsions were characterized using a Turbiscan LabExpert with a thermostatic system. The physical-chemical properties of the EO emulsions were determined using the respective Collaborative International Pesticides Analytical Council (CIPAC) methods The results indicated that the EO emulsions of isoprothiolane with the advantages of environmental friendly, stabilization, and high efficiency is prepared by the environmentally friendly, high boiling point, heavy aromatic solvent S200 and the polymeric emulsifier A-7. The polymer emulsifier A-7 promotes the stability of the EO emulsions better than the conventional surfactant. The water-in-oil emulsion represented an improved dosage form in terms of pesticide properties: oil as the continuous phase of the EO emulsion has better anti evaporation performance, and the stable EO emulsion can reach the foliage and spread quickly, which can improve the deposition on target. This study provides valuable information for the use of EO emulsions for a wide range of applications, especially in UAVs without dilution.