Controlling high-speed droplet splashing and superspreading behavior on anisotropic superhydrophobic leaf surfaces by ecofriendly Pseudogemini surfactants.

Background: Efficient deposition of high-speed droplets on superhydrophobic leaf surfaces remains an important challenge. For anisotropic wired superhydrophobic leaf surfaces, the splashing phenomenon is especially serious because it leads to the low effective utilization of pesticides by biological targets. The lost pesticides cause serious ecological environment pollution, therefore there is an urgent need to develop a green and sustainable cost-effective strategy to achieve efficient deposition of high-speed droplets on anisotropic superhydrophobic leaf surfaces at low dosage.

Results: One type of green pseudogemini surfactant is constructed based on fatty acids and hexamethylenediamine by electrostatic interaction to control the splashing and spreading of high-speed droplets on superhydrophobic surfaces. The formed surfactant can not only achieve complete inhibition of the bouncing of droplets, but also promote rapid spreading on superhydrophobic leaf surfaces at very low usage. The efficient deposition and superspreading phenomenon are attributed to the rapid migration and adsorption of the surfactant from the dynamic spherical micelles at the newly formed solid-liquid interface, the network-like aggregated spherical micelles, and the Marangoni effect caused by the surface tension gradient. Moreover, the surfactant shows an excellent synergistic effect with herbicides to control weeds by inhibiting droplet splashing.

Conclusion: This work provides a simpler, more effective and sustainable approach to utilize aggregated spherical micelles rather than conventional vesicles or wormlike micelles to improve the droplet deposition on superhydrophobic leaf surfaces and reduce the impact of surfactants and pesticides on the ecological environment. © 2023 Society of Chemical Industry.