Effect of Polyisobutylene Succinimide on the Physical Stability of an Environmentally Friendly Pesticide Oil Dispersion Suspension

Abstract

Oil dispersible suspension concentrates are safe, green, and environmentally friendly formulations. Problems such as layering, pasting, and bottoming are frequently encountered during the production, storage, and transportation process. Polyisobutylene succinimide functions as a dispersant and exhibits great potential to improve the physical stability of the oil dispersible suspension concentrate. From a microscopic perspective, the sorption characteristics of the polyisobutylene succinimide dispersant T151 on penoxsulam particle surfaces were comprehensively evaluated with XPS, FTIR, and SEM. The T151 adsorption procedure complied with a pseudo-second-order kinetic adsorption model, and it was a kind of physical sorption with an Ea of 22.57 kJ⋅mol⁻¹. The T151 sorption model was consistent with the Langmuir isotherm. The adsorption process was spontaneous and followed by an entropy increase. The ΔH^θ of dispersant T151 on the surface of penoxsulam particles was 31.59 kJ⋅mol⁻¹. The adsorption procedure was endothermic, and the primary force was hydrogen bonding. The XPS results showed that the F and S electronic peaks at the penoxsulam interface decreased, and that the C electronic peak increased significantly after the adsorption of dispersant T151, indicating the adsorption on the surface of penoxsulam particles. The results of this study provide a vital theoretical basis for the application of polyisobutylene succinimide dispersants in oil dispersible suspension systems.