Unexpected monolayer-to-bilayer transition of arylazopyrazole surfactants facilitates superior photo-control of fluid interfaces and colloids

Christian Honnigfort, Richard A. Campbell, Jörn Droste, Philipp Gutfreund, Michael Ryan Hansen, Bart Jan Ravoo, Björn Braunschweig

Research output: Contribution to journalArticlepeer-review

Abstract

Interfaces that can change their chemistry on demand have huge potential for applications and are prerequisites for responsive or adaptive materials. We report on the performance of a newly designed n-butyl-arylazopyrazole butyl sulfonate (butyl-AAP-C 4S) 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 -1) and surface excess (ΔΓ > 2.9 μmol m -2) demonstrate superior performance of the butyl-AAP-C 4S amphiphile to that of existing ionic surfactants. Neutron reflectometry and vibrational 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 dramatic consequences at larger length scales as highlighted by applications like the light-triggered collapse of aqueous foam which is tuned from high (>1 h) to low (<10 min) stabilities and light-actuated particle motion via Marangoni flows.

Original languageEnglish
Pages (from-to)2085-2092
Number of pages8
JournalChemical Science
Volume11
Issue number8
Early online date8 Jan 2020
DOIs
Publication statusPublished - 28 Feb 2020

Fingerprint

Dive into the research topics of 'Unexpected monolayer-to-bilayer transition of arylazopyrazole surfactants facilitates superior photo-control of fluid interfaces and colloids'. Together they form a unique fingerprint.

Cite this