title: Method for wettability characterization based on contact line pinning.
abstract: We demonstrate an efficient and reliable method for wettability characterization by determining the contact angle theta which a liquid-vapor interface makes with a solid wall. The purpose is to overcome the difficulties, related to the curvature of the liquid-vapor interface, which make measurements of theta rather uncertain, especially on the micro- and nanoscale. The method employs a specially designed slitlike channel in contact with a reservoir whereby the wettability of one of the slit walls is to be examined whereas the other (auxiliary) wall is separated by half into a lyophilic and a lyophobic part so as to pin the incoming fluid and fix the one end of the liquid-vapor interface. In the present work, the physical background of the method is elucidated theoretically while the method's applicability is demonstrated by molecular-dynamics simulation of a typical Lennard-Jones fluid, in contact with an atomistic wall. The wettability of the latter, as described by the corresponding contact angle theta, is accurately determined by variation of the liquid-wall interaction in a very broad interval.
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, D-55099 Mainz, Germany.
authors.forename: D I
authors.initials: DI
authors.lastname: Dimitrov
authors.forename: A
authors.initials: A
authors.lastname: Milchev
authors.forename: K
authors.initials: K
authors.lastname: Binder