title: Stick-slip of the three-phase line in measurements of dynamic contact angles.
abstract: Contact angles of a series of n-alkanes (i.e., n-heptane to n-hexadecane) are studied on two functionalized maleimide copolymers (i.e., poly(ethene-alt-N-(4-(perfluoroheptylcarbonyl)aminobutyl)maleimide) (ETMF) and poly(octadecene-alt-N-(4-(perfluoroheptylcarbonyl)aminobutyl)maleimide) (ODMF)). On the homogeneous ETMF films, all liquids show a smooth motion of the three-phase line. In contrast, on ODMF surfaces that are found to consist of mainly fluorocarbons and small patches of hydrocarbons, short-chain n-alkanes show a stick-slip pattern. By increasing the chain length of the probe liquids, stick-slip is reduced significantly. The phenomenon is discussed in the framework of the Cassie equation. It is found that the upper limit of contact angles in the stick-slip pattern is given by the advancing angle that would be obtained on the pure fluorocarbon surface, whereas the lower limit of the stick-slip pattern is given by the Cassie angle.
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario, Canada M5S 3G8.
authors.forename: Hossein
authors.initials: H
authors.lastname: Tavana
authors.forename: Guocheng
authors.initials: G
authors.lastname: Yang
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Yip
authors.forename: Dietmar
authors.initials: D
authors.lastname: Appelhans
authors.forename: Stefan
authors.initials: S
authors.lastname: Zschoche
authors.forename: Karina
authors.initials: K
authors.lastname: Grundke
authors.forename: Michael L
authors.initials: ML
authors.lastname: Hair
authors.forename: A Wilhelm
authors.initials: AW
authors.lastname: Neumann