非离子表面活性剂Triton X-100溶液在不同生长期小麦叶片表面的润湿行为

Wettability of Triton X-100 on Wheat(Triticumaestivum) Leaf Surfaces with Respect to Developmental Changes

选择不同生长期小麦叶片,利用座滴法研究了非离子表面活性剂Triton X-100在小麦叶片表面接触角,考察浓度对接触角、粘附张力、固-液界面张力及润湿状态的影响。研究表明,在低浓度下,表面活性剂分子在气-液界面吸附量(ΓLV)和固-液界面吸附量(Γ'SL)相似,但吸附量较少形成了不饱和吸附层,接触角保持不变,其润湿状态为Cassie-Baxter状态;当浓度进一步增加,液滴突破叶片表面三维立体结构中存在的钉扎效应,取代空气层而处于Wenzel状态,接触角陡降,同时Γ'SL/ΓLV远大于1;当浓度超过临界胶束浓度(CMC)时,表面活性剂分子在气-液界面和固-液界面形成饱和吸附层,并产生毛细管效应,使溶液在小麦叶片三维立体结构中产生半渗透过程,此时接触角保持不变。

In this research, the wetting behavior of nonionic surfactant Triton X-lO0 on wheat leaf surfaces at different developmental stages has been investigated based on the surface free energy, contact angle, adhesion tension, and liquid-solid interracial tension. The results show that the contact angle remains constant with low adsorption at the liquid-air （ΓLV） and liquid-solid （ΓsL） 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/ΓLV 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.