Regensburg 2002 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 15: Poster: Dünne Filme, Monolagen und Oberfl
ächen

CPP 15.3: Poster

Mittwoch, 13. März 2002, 16:30–18:00, B

pH-dependency of the adsorption kinetics of carboxy-terminated alkanethiolate monolayers — •Karin Heister, Michael Himmelhaus, and Michael Grunze — Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg

Alkanethiolates can self-assemble on metal surfaces to a densely packed well-ordered monolayer. The endgroup functionality defines the surface properties of the resulting system and enables thereby the application of this self-assembled monolayer (SAM) in terms of wetting, lubrication, lithography or adhesion.

The choice of the endgroup functionality, however, effects not only the interaction between the endgroup and the environment. The forces among neighbored functionalities and the interaction with the solvent have to be considered to understand the formation of a funktionalized SAM. One parameter that we have shown to be decisive for the aggregation kinetics is the pH-value. Time resolved Second Harmonic Generation (SHG) measurements on the adsorption process of carboxy-terminated alkanethiols have shown a strong dependency of the adsorption rate on the pH-value of the solvent during the wet chemical self-assembly. The SAM formation is significantly increased in basic solvents in comparison to acidic solvents. This result is essential for the use of SAMs in biological applications and enlightens the forces that are introduced to a SAM by the endgroup functionality.