Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 47: Poster: Interfaces and Thin Films

CPP 47.18: Poster

Mittwoch, 9. März 2016, 18:15–21:00, Poster B2

Molecular Structure of Photo-switchable Azo Dye/Surfactant Mixtures at Air-Water Interfaces — •Saskia Streubel, Felix Schulze-Zachau, and Björn Braunschweig — Friedrich-Alexander University Erlangen-Nürnberg (FAU), Institute of Particle Technology (LFG), Erlangen, Germany

Adsorption and molecular structure of disodium 6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphthalenesulfonate (Sunset Yellow) dye mixtures with cetyltrimethylammonium bromide (CTAB) surfactants was studied at air/water interfaces using tensiometry, ellipsometry and vibrational sum-frequency generation (SFG). In addition to effects of the mixing ratio on interfacial adsorption, we have investigated in detail the influence of light-induced isomerization of Sunset Yellow dye and its complexes with CTA⁻ ions on the molecular structure at air/water interface. Here, different isomers were generated by irradiating the samples with UV light which leads to less-hydrophobic cis-isomers, while backward transformation to trans-isomers could be achieved by blue light. In addition to information on interfacial composition, conformation and charging state that was gained by applying SFG spectroscopy and ellipsometry, we have investigated the properties of macroscopic foam as a function of mixing ratio and UV light exposure and deduce structure-property relations from the molecular to the macroscopic level.