Mechanism for Stripe Pattern Formation on Hydrophilic Surfaces by Using Convective Self-Assembly

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• 作者：Satoshi Watanabe ; Koji Inukai ; Shunsuke Mizuta ; Minoru T. Miyahara
• 刊名：Langmuir
• 出版年：2009
• 出版时间：July 7, 2009
• 年：2009
• 卷：25
• 期：13
• 页码：7287-7295
• 全文大小：1021K
• 年卷期：v.25,no.13(July 7, 2009)
• ISSN：1520-5827

文摘

We have studied the formation of stripe patterned films of ordered particle arrays on completely solvophilic substrates by using a self-organization technique. In this method, a substrate immersed in a suspension is withdrawn vertically at a controlled temperature. We have also systematically examined the effects of several experimental parameters. Well-defined stripes spontaneously form at the air−solvent−substrate contact line because of a very dilute suspension in a quasi-static process. The stripe width depends on particle concentration, withdrawal rate, and surface tension, while the stripe spacing depends on the thickness of stripes, surface tension, and type of substrate. A stripe width and the adjacent spacing show a clear correlation, strongly indicating the synchronized formation of a stripe and the next spacing. The evaporation rate does not affect stripe width and spacing but determines the growth rate of stripe patterned films. Based on these results, we propose a new mechanism for stripe formation, which is neither a stick−slip motion of the contact line nor dewetting but a negative feedback of particle concentration caused by a concavely curved shape of the meniscus, demonstrating not only its qualitative but also its quantitative validity.