AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS-ThP

Paper SS-ThP28
Liquid Selection using Sliding Behavior of Droplets on Line-Patterned Hydrophobic Surfaces

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: S. Suzuki, KAST (Kanagawa Academy of Science and Technology) and Tokyo Institute of Technology, Japan
Authors: A. Nakajima, Tokyo Institute of Technology, Japan
S. Suzuki, KAST (Kanagawa Academy of Science and Technology) and Tokyo Institute of Technology, Japan
K. Tanaka, Tokyo Institute of Technology, Japan
M. Sakai, KAST, Japan
A. Hashimoto, KAST, Japan
Y. Kameshima, KAST and Tokyo Institute of Technology, Japan
N. Yoshida, KAST and CCR, Tokyo University, Japan
K. Okada, Tokyo Institute of Technology, Japan
Correspondent: Click to Email
Technologies of hydrophobic coating have been important for various industrial items. The evaluation of a solid surface's hydrophobicity is divided into two branches: static hydrophobicity and dynamic hydrophobicity. For assessing solid surfaces' dynamic hydrophobicity, information related to the speed at which the droplet can be removed from the surface at a certain tilt angle is becoming important. Surface composition patterns using self-assembled monolayers (SAMs) were fabricated recently using photolithography. Wettability on well-defined micropatterned surfaces with different surface free energy has been specifically examined, although wetting behavior of droplets on homogeneous surfaces has mainly been studied. The relationship between heterogeneous patterned surface and dynamic hydrophobicity on patterned surfaces is not precisely reported. In the present paper, we demonstrate liquid selection effect using sliding behavior of droplets on the line-patterned hydrophobic surfaces. A cleaned Si wafer was micro-patterned by fluoroalkylsilane (FAS) and octadecyltrimethoxysilane (ODS). When a Si wafer with the patterned lines was rotated to a certain angle in plane and inclined from horizontal position, droplets of water or ethanol solution slid down on the surface with some displacement to line direction with changing their sliding velocity. This behavior depends on not only surface energy and droplet mass but also a rotation angle and patterning structure. Detailed discussion on the relationship among these factors will be presented.