An efficient organosilane-modified polycarboxylate dispersant with excellent dispersing performance and superior wettability for tebuconazole suspension concentrate

Abstract

The dispersion stability and wettability of suspension concentrates are beneficial for improvement of the utilization rate of pesticides. Herein, four kinds of novel organosilane-modified polycarboxylate dispersants P(AA₃-APEG₁-Si_x) with different silicone contents ranging from 0 to 0.5 mol were successfully synthesized using acrylic acid (AA), allyl polyethoxyether (APEG-1000) and organosilicon modifier 3-(trimethoxysilyl)propylmethacrylate (MAPTMS) as monomers, and their surface properties were systematically investigated. Meanwhile, 25% tebuconazole (TEB) suspension concentrate (SC) was milled with the four P(AA₃-APEG₁-Si_x (SC_{P(AA3-APEG1-Six)}), and the influences of P(AA₃-APEG₁-Si_x) on the zeta potential, particle size, suspension rate and rheological behaviors of the 25% TEB SC were also studied. The results showed that P(AA₃-APEG₁-Si_0.5) had the lowest surface tension by maintaining an AA:APEG-1000 mole ratio of 3 : 1, and changing the MAPTMS additive amount from 0 to 0.5 mol. Additionally, the obtained TEB SC_{P(AA3-APEG1-Six)} system exhibits shear thinning behavior under high shearing rate, showing typical features of a pseudo-plastic non-Newtonian fluid, which conforms to the Power-law model. More importantly, the SC_{P(AA3-APEG1-Six)}, especially for P(AA₃-APEG₁-Si_0.5), exhibited relatively minimum change in particle size and zeta potential compared to that of the unmodified polymers, and displayed superior suspension rate. Significantly, TEB SC_{P(AA3-APEG1-Six)} showed excellent wetting and spreading behavior on plant leaves, which contributes to obviously improving pesticide utilization.