Reversible Phase Transitions of Anionic and Cationic Surfactant Mixtures Drive Shape Morphing Droplets

Area of Science:

• Materials Science
• Soft Matter Physics
• Chemical Engineering

Background:

• Converting chemical signals to mechanical responses is vital in biology but challenging in synthetic systems.
• Existing stimuli-responsive surfactants lack the force amplification for transient liquid structuring.

Purpose of the Study:

• To introduce a novel chemo-mechanical transduction mechanism for actuating droplets.
• To enable the creation of programmable, hierarchically structured, all-liquid matter.

Main Methods:

• Utilized reversible, light-induced crystal-to-coacervate phase transitions of photo-responsive surfactant assemblies.
• Employed anionic sodium dodecylsulfate and cationic azobenzene-based surfactants.
• Demonstrated a spring-like charging and latch-controlled release mechanism.

Main Results:

• Achieved rapid changes in interfacial tensions up to 900 times greater than conventional systems.
• Successfully actuated droplets through controlled phase transitions.
• Showcased a new method for transient liquid structuring.

Conclusions:

• The developed mechanism offers unprecedented control over chemo-mechanical signal conversion in liquid systems.
• This work paves the way for programmable, all-liquid matter with dynamic physical properties.
• Provides fundamental insights into energy-dissipative materials design.