Berlin 2015 – scientific programme

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DS: Fachverband Dünne Schichten

DS 22: Interfaces and Thin Films III (joint session with CPP)

DS 22.7: Talk

Wednesday, March 18, 2015, 11:15–11:30, C 243

Light-Controlled Molecular Zippers based on Azobenzene Main Chain Polymers — •Christopher Weber¹, Tobias Liebig¹, Anton Zykov¹, Linus Pithan¹, Sebastian Bommel^1,2, David Bléger³, and Stefan Kowarik¹ — ¹Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin — ²Deutsches Elektronen-Synchrotron, 22607 Hamburg — ³Institut für Chemie, Humboldt-Universität zu Berlin, 12489 Berlin

We report that thin films of azobenzene main chain polymers with interdigitating dodecyl side chains (molecular zippers) can be switched reversibly with light between a semicrystalline and an amorphous state, corresponding to a closed and open state of the molecular zippers. Simultaneous time-resolved x-ray diffraction and optical spectroscopy measurements show that the kinetics of the amorphization of the crystalline domains is about 12 times slower than the photoisomerization of the azobenzene chromophores. Our findings suggest that the amorphization is triggered by E-Z isomerization of a small amount of azobenzene chromophores within the polymer film and that the slower kinetics of the photoinduced amorphization is determined by structural and topological constraints and not by a different isomerization mechanism in crystalline domains.