Regulating droplet impact and wetting behaviors on hydrophobic leaves using a nonionic surfactant

Droplet rebound from hydrophobic leaves is a major factor influencing pesticide utilization. The use of a surfactant is a major strategy to reduce droplet rebound, promoting pesticide deposition on hydrophobic agricultural plant leaves. However, most surfactants known to regulate droplet rebound are either anionic or cationic. In this study, ethoxylated propoxylated 2-ethyl-1-haxanol (EH 6) was identified as a nonionic surfactant that inhibits droplet rebound while promoting the complete spreading of the droplet on hydrophobic leaves. Compared with the widely reported nonionic surfactant Tween 20, EH 6 performs better at concentrations above 0.3%. This phenomenon can be attributed to the rapid migration of EH 6 from the bulk to the newly generated interface, significantly reducing the surface tension. We introduce a simple and effective strategy that can be used to enhance droplet deposition on hydrophobic plant surfaces, which may offer future economic and environmental benefits.