Structuring of polymer surface by evaporation of sessile microdrops [Elektronische Ressource] / Guangfen Li

Structuring of polymer surface by evaporation of sessile microdrops DISSERTATION zur Erlangung des Grades "Doktor der Naturwissenschaften" am Fachbereich Chemie/Pharmazie der Johannes Gutenberg-Universität in Mainz vorgelegt von Master-Chem. Guangfen Li aus Tianjin (V. R. China) Mainz – 2007 Die vorliegende Arbeit wurde unter Betreung von Herrn Prof. Dr. Hans-Jürgen Butt im Zeitraum zwischen April 2004 bis März 2007 am Max-Plank-Institut für Polymerforschung, Mainz, Deutschland angefertigt. IIABSTRACT ABSTRACT In this thesis different homemade experimental setups were used to study (1) the evaporation dynamics of liquid mcirodrops on smooth, insoluble planar surfaces, (2) the microstructuring of soluble polymer surfaces by solvent drops, and (3) the interfacial tension between two immiscible slugs in a microcapillary, where evaporation is avoided. (1) The evaporation dynamics of pure water drops on self-assembled monolayers of thiols and disulfides (SAMs) on gold showed a stronger pinning of the rim of the droplet, the more hydrophilic the surface was. The hydrophilicity was tuned by the end-groups of the SAM alkyl chains. The total evaporation time, t , for drops with different initial volumes, V , tot 0bobeys a power law of the type V = a⋅t with an exponent b differing from the theoretical 0 totexpected value of 1.5 for a diffusion-limited evaporation.