Wrapping with a splash: High-speed encapsulation with ultrathin sheets.

Area of Science:

• Complex Fluids
• Materials Science
• Fluid Dynamics

Background:

• Surfactants are crucial for isolating liquid drops in immiscible phases.
• Thin elastic sheets can spontaneously wrap liquid drops via capillary forces.
• Existing encapsulation methods lack speed, continuity, and scalability.

Purpose of the Study:

• To develop a rapid, continuous, and scalable process for encapsulating liquid drops using thin elastic films.
• To leverage droplet impact dynamics for robust encapsulation.
• To achieve targeted three-dimensional (3D) shapes and near-perfect seams in wrappings.

Main Methods:

• Exploiting the fast dynamics of droplet impact.
• Utilizing ultrathin polymer films for wrapping oil droplets in a water phase.
• Tailoring the two-dimensional (2D) boundary of polymer films to control 3D wrapping shapes.

Main Results:

• Achieved robust encapsulation of oil droplets by ultrathin polymer films during violent splashing events.
• Generated wrappings with optimal shapes for maximizing enclosed fluid volume.
• Produced wrappings with near-perfect seams and demonstrated generality for both oil-in-water and water-in-oil systems.

Conclusions:

• Droplet impact offers a viable, fast, and scalable method for film-based encapsulation.
• The technique allows for precise control over wrapping shape and seam quality.
• This method broadens the possibilities for encapsulating diverse liquid drops in complex fluid systems.