Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 18: Poster: Polymer Dynamics
CPP 18.24: Poster
Dienstag, 12. März 2013, 18:15–20:15, Poster C
Switching single macromolecules at modified graphene surfaces — •Chien-Li Lee1, David Bléger2, Stefan Hecht2, and Jürgen Rabe1 — 1Institut für Physik, Humboldt-Universität zu Berlin — 2Institut für Chemie, Humboldt-Universität zu Berlin
Introducing azobenzene moities into polymers has recently been shown to allow for optically switching the aggregation behavior of the polymer in solution, which has been attributed to rod-coil transitions [1]. Due to the difficulty of isolating single switchable azobenzene-containing polymers on solid substrates, they were studied so far in aqueous solutions, thin films and bulk materials, thereby reflecting ensemble properties.
Here we present an approach to switch single macromolecules immobilized on a modified graphene surface. A synthetic rigid-rod polymer [1] incorporating azobenzene photoswitches in the backbone was deposited from aqueous solution onto a graphite surface precoated with an oriented monolayer of octadecylamine [2]. Single rod-like polymers aligned by the substrate have been imaged by scanning force microscopy. Photoisomerization back and forth between trans and cis at different wavelengths leads to shrinking and stretching, respectively, as well as some local movements of the macromolecules on the surface.
[1] David Bléger, T. Liebig, R. Thiermann, M. Maskos, J. P. Rabe, and S. Hecht Angew. Chem. Int. Ed. 2011, 50, 12559.; [2] N. Severin, I.M. Okhapkin, A.R. Khokhlov, and J.P. Rabe, Nano Lett. 2006, 6 1018