Dresden 2020 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 50: Poster Session III

CPP 50.14: Poster

Tuesday, March 17, 2020, 14:00–16:00, P1C

Photosensitive Surfactants at Hydrophilic and Hydrophobic Surfaces — •Maren Umlandt, David Feldmann, and Svetlana Santer — University of Potsdam, Potsdam, Germany

Here we report the adsorption kinetics of photosensitive azobenzene containing surfactants on different substrates under illumination with UV and green light. The work is motivated by the newly discovered phenomena of light driven diffusioosmosis (LDDO) where flow is generated at the solid/liquid interface [1]. Colloidal particles trapped at solid/liquid interface move passively within this LDDO flow, and can be arranged in different pattern, removed selectively or gathered on demand. The main ingredient of this process is photosensitive azobenzene containing surfactant which undergoes photo-isomerization reaction from trans- to cis- state with corresponding changes in physical properties such as dipole moment, shape and size. In trans-state the molecule is hydrophobic, while in cis-state hydrophilic. Here we perform analysis of the surfactant adsorption on a hydrophilic and a hydrophobic surfaces using Zeta potential and quartz crystal microbalance (QCM-D) measurements. We analyses the adsorption isotherms in terms of four and five step models. It has been shown that the adsorption of trans- and cis-isomers differs significantly on each type of surfaces.

1. D. Feldmann, S. S. Maduar, N. Lomadze, O. Vinogradova and S. Santer, Scientific Reports, 6, 36443 (2016).