Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 25: Poster Session II
CPP 25.46: Poster
Dienstag, 2. April 2019, 14:00–16:00, Poster B1
Structure and Switching of Azobenzene Layers Physisorbed on Mica and Glass — •Amrita Pal1, Olga Guskova1, Alexey Kopyshev2, and Svetlana Santer2 — 1Institute Theory of Polymers, IPF Dresden, Germany — 2Institute of Physics and Astronomy, University of Potsdam
We study the photoswitchable amphiphilic molecules [1] with charged trimethyl ammonium head group and the hydrophobic tail consisting of alkyl and azobenzene (azo) segments. Being physisorbed on mica or glass surfaces, these molecules build the self-assembled monolayers. The reversible photoswitching of thickness of the layers is investigated in both AFM experiments and DFT/MD simulations. The in-situ AFM experiments show that the photoisomerization of the azo molecules under irradiation with light of different wavelength results in significant change of morphology, i.e. thickness and topography of azo multilayers. In DFT, the triple zeta basis set and generalized gradient approach, hybrid and range separated hybrid functionals are used to obtain the isomeric properties at the molecular level. Also, a periodic DFT calculation is performed for a single molecule adsorbed onto a small mica cluster to compare the results of quantum and classical simulations. The DFT calculations of the azo isomers in vacuum and in adsorbed state reveal the influence of the surface on their electronic properties. The MD simulation of denser layers consisting of many azo molecules uncovers their detailed structures and allows a direct comparison with AFM data. We acknowledge support from DFG, GU 1510/5-1. [1] Montagna, M. et al. Langmuir 34(1), 311 (2018)