School of Chemistry, The University of Melbourne, Melbourne, Victoria, Australia.
Faraday Discuss. 2010;146:223-32; discussion 283-98, 395-401. doi: 10.1039/b927136h.
Two scales of roughness are imparted onto silicon surfaces by isotropically patterning micron sized pillars using photolithography followed by an additional nanoparticle coating. Contact angles of the patterned surfaces were observed to increase with the addition of the nanoparticle coating, several of which, exhibited superhydrophobic characteristics. Freeze fracture atomic force microscopy and in situ synchrotron SAXS were used to investigate the micro- and nano-wettability of these surfaces using aqueous liquids of varying surface tension. The results revealed that scaling different roughness morphologies result in unique wetting characteristics. It indicated that surfaces with micro, nano or dual scale roughness induced channels for the wetting liquid as per capillary action. With the reduction of liquid surface tension, nano-wetting behaviour differed between superhydrophobic and non-superhydrophobic dual-scale roughness surfaces. Micro-wetting behaviour, however, remained consistent. This suggests that micro- and nano-wetting are mutually exclusive, and that the order in which they occur is ultimately governed by the energy expenditure of the entire system.
通过各向同性地使用光刻技术在硅表面形成微米级支柱，并随后进行纳米粒子涂层，赋予硅表面两种粗糙度。观察到带有纳米粒子涂层的图案化表面的接触角随着纳米粒子涂层的增加而增加，其中一些表现出超疏水性特征。使用具有不同表面张力的水溶液，通过冷冻断裂原子力显微镜和原位同步加速器小角 X 射线散射（SAXS）研究这些表面的微观和纳米润湿性。结果表明，不同粗糙度形态的缩放导致独特的润湿特性。这表明具有微、纳米或双重粗糙度的表面根据毛细作用诱导润湿液体的通道。随着液体表面张力的降低，纳米润湿行为在超疏水和非超疏水双重粗糙度表面之间有所不同。然而，微润湿行为保持一致。这表明微润湿和纳米润湿是相互排斥的，它们发生的顺序最终由整个系统的能量消耗决定。
