Regulating Droplet Dynamics via Wormlike Micelle Networks: From Splash Suppression to Precise Confined Spreading

Area of Science:

• Fluid Dynamics
• Materials Science
• Surface Chemistry

Background:

• High-speed droplet impact is crucial for applications like inkjet printing and precision agriculture.
• Controlling droplet splashing and ensuring uniform spreading on hydrophilic surfaces presents significant challenges.

Purpose of the Study:

• To develop a strategy for modulating droplet dynamics to achieve splash-free and uniform deposition.
• To investigate the role of surfactant aggregate structural transitions in controlling droplet impact.

Main Methods:

• Induction of structural transition in anionic surfactant (SDS) aggregates using quaternary ammonium cations (CT1, CT4).
• Formation of an internal wormlike micelle (WLM) network.
• Demonstration on high-speed droplet impact onto cotton fabrics.

Main Results:

• The WLM network facilitates splash-free, spatially confined deposition.
• Synergistic interaction between CT4-SDS aggregates and cellulose backbone inhibits initial spreading.
• WLM network entanglement with cellulose fibers creates an interfacial mechanical pinning effect, immobilizing the contact line.

Conclusions:

• A novel mechanistic pathway for steering droplet impact kinetics is presented.
• Insights into designing complex fluids for high-performance functional coating and deposition are provided.
• The WLM network enables stabilized liquid films and uniform circular deposition.