Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 5: Interfaces

CPP 5.8: Vortrag

Montag, 23. März 2009, 12:15–12:30, ZEU 160

Tuning of surface properties by self assembled mixed monolayers — •David Polster, Harald Graaf, and Christian von Borczyskowski — Center of Nanostructured Materials and Analytics, University of Technology Chemnitz, 09107 Chemnitz, Germany

Self assembled monolayers covalently bond on silicon surfaces were prepared from different mixture ratios of 1-decene (DEC) and methyl-10-undecenoate (UND). A two step radical reaction induced by heat treatment was used to prepare the monolayers. The prepared films have been studied with contact angle measurements, using water as polar liquid and diiodmethane as dispersive liquid as well as atomic force microscopy (AFM). For the mixed monolayers a decrease in the water contact angle, 110° to 75°, was found with increasing ratio of UND in the monolayer. Smaller contact angles could be explained by increasing polarity of the surface induced by the increasing amount of ester groups containing beside dispersive also polar character. Furthermore work of adhesion increases by higher polarity of the mixed monolayers and thereby the process of wetting happens easier and liquids spreads wider. In addition angle hysteresis and mole free energy of dewetting were constant. Beside contact angle investigations scanning probe measurements showed that all surfaces were extremely smooth. By AFM force spectroscopy it could be shown that with increasing polarity of the surface also a slight increase of adhesive force between AFM tip and surface was found.