Dresden 2020 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 88: Responsive and Adaptive Systems
CPP 88.5: Talk
Thursday, March 19, 2020, 10:30–10:45, ZEU 114
Unexpected Monolayer-to-Bilayer Transition of Arylazopyrazol Surfactants Facilitates Superior Photo-Control of Fluid Interfaces — •Christian Honnigfort1, Richard A. Campbell2, Dana Glikman1, Marco Schnurbus1, Philipp Gutfreund3, Bart Jan Ravoo1, and Björn Braunschweig1 — 1University of Münster, Germany — 2University of Manchester, United Kingdom — 3Institut Laue-Langevin, France
Interfaces that can change their chemistry on demand have huge potential for applications and are prerequisite for responsive or adaptive materials. We report on the performance of a newly designed n-butyl-arylazopyrazole butyl sulfonate (butyl-AAP-C4S) surfactant that can change its structure at the air-water interface by E/Z photo-isomerization in an unprecedented way. Large and reversible changes in surface tension (Δγ ∼ 27 mN/m) and surface excess (Δ Γ >2.9 µmol/m2) demonstrate superior performance of the butyl-AAP-C4S amphiphile to that of existing ionic surfactants. Neutron reflectometry and sum-frequency generation spectroscopy reveal that these large changes are caused by an unexpected monolayer-to-bilayer transition. This exceptional behavior is further shown to have also dramatic consequences at larger length scales as highlighted by two application like the light-triggered collapse of aqueous foam which is tuned from high (>1h) to low (<10min) stabilities and light-actuated particle motion via Marangoni flows.