超疏水材料在液压作用下的润湿行为

Wetting Behavior of Superhydrophobic Materials under Hydraulic Pressure

在超疏水界面光反射的基础上,用抽真空和压力驱动的方法研究了荷叶、超疏水ZnO阵列在水下的界面润湿行为和微结构中截留气体对其润湿行为的影响。结果表明:当有气体截留时受所加最大压力和微结构几何形貌的影响,超疏水界面在加压和减压过程中表现出不同的润湿可逆性;超疏水材料表面微结构中截留的气体能延迟水的侵入并提高超疏水稳定性;在特定情况下,随着外部压力的减小截留气体的膨胀能推动和排出侵入的水并引导反润湿过程。因此,截留气体有利于超疏水状态的存在。由于三相接触线密度的不同,纳米结构在压力作用下比微米结构表现出更为优异的疏水稳定性。

Based on the reflection property of water-superhydrophobic material interface, the underwater wetting behavior of natural lotus leaf and superhydrophobic ZnO arrays was investigated by varying the wetting status with vacuum pumping and pressure-driven with special attention on the influence of the entrapped air in microstructures of their surface. The results show that when air was trapped on the surface, the water-superhydrophobic material interface exhibits different wetting reversibility in the course of compressing and decompressing, which may be affected by the maximum pressure exerted and the morphology of the surface microstructure. The entrapped air in the surface microstructures can delay the intrusion of water and enhance the stability of superhydrophobicity. In certain case, with the decrease of external pressure the expansion of the trapped air can even push out the intruded water and lead to the de-wetting process, therewith benefitial to the stability of superhydrophobic state. Due to the difference in density of trip-phase contact line, the microstructure in nano-scale show better hydrophobic stability rather than that of the microstructures in micro-scale under external pressure.