Promotion of droplet deposition, diffusion-wetting and retention on hydrophobic surfaces by nonionic star-shaped oligomeric surfactants

Abstract

Massive wastage of pesticides has caused significant environmental pollution and economic loss. However, existing strategies to control loss of pesticides are complex or step-specific. Here, nonionic star-shaped surfactants that can simultaneously achieve comprehensive regulation of deposition, diffusion-wetting and retention are designed and synthesized, which greatly improve the utilization efficiency of pesticides while reducing environmental risks. Structure–activity relationships for the surfactants were elucidated, and their interactions with hydrophobic surfaces were studied in detail. The results show that the addition of nonionic star-shaped oligomeric surfactant to a solution decreased droplet bouncing, increased the diffusion-wetting area, slowed droplet evaporation; and the surfactant III-8b showed the best performance. On the basis of these results, III-8b was used as a synergist for Glyphosate-isopropylammonium 41 % AS. The biological activity test showed that the herbicidal activities of the surfactant III-8b-containing glyphosate solution against Pharbitis nil (L.) Choisy and Echinochloa crusgalli (L.) were substantially better than the activities in the absence of surfactant.