Abstract:

In this research, the wetting behavior of nonionic surfactant Triton X-100 on wheat leaf surfaces at different developmental stages has been investigated based on the surface free energy, contact angle, adhesion tension, and liquid-solid interfacial tension. The results show that the contact angle remains constant with low adsorption at the liquid-air (Γ_LV) and liquid-solid (Γ'_SL) interfaces at low concentration, and the wetting state is in the Cassie-Baxter state. On increasing the concentration, the contact angle decreases sharply and the ratio of Γ'_SL/Γ_LV becomes more than 1. Meanwhile, the droplet overcomes the pinning effect to displace the air among three-dimensional wax layers and is in the Wenzel state. When the concentration becomes over critical micelle concentration (CMC), a saturated adsorption film forms at the interfaces, and the hemiwicking process occurs among micro/nano structures because of the capillary effect, then the contact angle remains constant.

Key words: Nonionic surfactant, Wheat leaf surfaces, Solid apparent surface free energy, Adsorption, Wetting state