Evidence of wettability variation on carbon nanofiber layers grown on oxidized silicon substrates

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• 作者：H. Nair ; R.M. Tiggelaar ; D.B. Thakur ; J.G.E. Gardeniers ; A. van Houselt ; L. Lefferts
• 关键词：Carbon nanofiber growth ; Tunable wettability ; Superhydrophobicity ; Microfluidic devices
• 刊名：Chemical Engineering Journal
• 出版年：2013
• 出版时间：1 July, 2013
• 年：2013
• 卷：227
• 期：Complete
• 页码：56-65
• 全文大小：4100 K

文摘

This paper describes how layers of carbon nanofibers (CNFs) with a controllable wettability can be synthesized by means of thermal catalytic chemical vapor deposition on nickel-based thin films on oxidized silicon supports. In order to achieve well-adhesive CNF-layers with a uniform surface coverage and tunable wettability without the necessity of post-synthesis treatments, a series of synthesis parameters is investigated: the pretreatment atmosphere (hydrogen or oxygen; 2 h, 500 ¡ãC), the use of ethylene (C₂H₄) or an ethylene/hydrogen (C₂H₄/H₂) mixture as hydrocarbon source, and the growth time (in the range 5-60 min).

Fast and uniform CNF-growth is found on reduced Ni-based thin films using C₂H₄/H₂ at a synthesis temperature of 635 ¡ãC. The CNF-layers on Ni are superhydrophobic or highly hydrophobic for all growth times, but their adhesion to the support is poor for growth times >30 min. In contrast, the adhesion of CNF-layers on Ni/Ta is excellent. Moreover, the wettability of these as-synthesized CNF-layers can be controlled by variation of the growth time: from superhydrophobic (?10 min) to hydrophilic (?50 min). CNF-layers with such tunable wettability can be easily integrated in flow channels of silicon-based microfluidic systems, thereby offering numerous applications.