Berlin 2024 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 46: Complex Fluids, Colloids, Micelles and Vesicles (joint session CPP/DY)

DY 46.2: Vortrag

Donnerstag, 21. März 2024, 15:30–15:45, H 0110

Light-induced manipulation of colloidal particles in a photosensitive polymer-dye system — •Anna López de Guereñu and Svetlana Santer — Room 2.025 University of Potsdam Physics and Astronomy Karl-Liebknecht-Str. 24-25 14476 Potsdam Germany

In this study, we explore the optical and physical properties of a photosensitive surfactant system consisting of mesoporous silica particles in an aqueous solution with a fluorescent dye and an azobenzene-containing surfactant. The latter undergoes reversible photo-isomerization from trans- to cis-configuration upon UV/blue light exposure on a picosecond timescale, offering precise control over particle aggregation. The formation of the dye/surfactant complex adds complexity to the system.

Light-driven diffusioosmosis (LDDO) facilitates remote colloid control, with mesoporous colloids acting as a source or sink for the surfactant, influencing mutual interactions between particles.

The surfactant's isomerization state determines its adsorption affinities, influencing particle interactions. The trans-isomer accumulates in pores and forms a complex with the dye, while the cis-isomer remains outside the pores. Upon irradiation, the cis-surfactant generates a diffusioosmotic flow, causing a repulsion of particles. Wavelength and intensity modulate this process, allowing to control these structures. The dye provides an additional dimension to the system, adding to its complexity due to its influence on the surfactant isomerization and the LDDO process.

Keywords: light-driven diffusioosmosis; porous silica; manipulation; azobenzene