Special CPM Seminar

Molecular toolkit for surface materials with switchable tribological functions

Johanna Blass

Leibniz-Institute for New Materials
Saarland University

Understanding the dynamics underlying adhesion and friction on the molecular scale is one of the main challenges in tribology. We have developed a new interface system based on cyclodextrin assemblies where friction and adhesion are caused by supramolecular bonds [1]. The interaction of a group of bonds is probed by the asperity of an AFM tip in aqueous environment. Connector molecules with two end groups form inclusion complexes with the cyclodextrin molecules on the tip and at the surface. By choosing different connector molecules we can tune the complexation strength and kinetics of the inclusion complexes and investigate how the cooperative action of single bonds affects friction and adhesion of the overall contact. Additionally, switchable adhesion and friction characteristics can be activated by external stimuli. In light-activated experiments, the binding between β-cyclodextrin and azobenzene derivatives can be switched by UV light [2].

[1] J. Blass, M. Albrecht, B.L. Bozna, G. Wenz, and R. Bennewitz, Nanoscale, 2015, 7, 7674.
[2] J. Blass, B.L. Bozna, M. Albrecht, J. A. Krings, B. J. Ravoo, G. Wenz, and R. Bennewitz, Chem. Commun., 2015, 51, 1830.