Unloading and reloading colloidal microcapsules with apolar solutions by controlled and reversible buckling

Area of Science:

• Materials Science
• Colloid Science
• Nanotechnology

Background:

• Polydimethylsiloxane (PDMS) microcapsules offer unique properties for encapsulation.
• Controlled release of encapsulated materials is crucial for various applications.
• Morphological changes in microcapsules can be induced by internal volume reduction.

Purpose of the Study:

• To introduce a new experimental method for encapsulating and releasing oils and fluorescent molecules.
• To investigate the controlled buckling of PDMS microcapsules.
• To demonstrate the tunable formation of microbowls and their loading capabilities.

Main Methods:

• Encapsulation of oils and fluorescent molecules into PDMS-filled siloxane shells.
• Controlled volume reduction of microcapsules via surfactant micelle dissolution of internal PDMS oil.
• Analysis of morphological changes based on the shell thickness to total particle radius ratio (d/Rt).

Main Results:

• Microcapsules with d/Rt ratio of 0.007-0.05 formed microbowls upon inner volume decrease.
• The amount of released oil is directly proportional to surfactant concentration, enabling tunable microbowl depth.
• Demonstrated successful loading of various oils (silicone oil, hydrocarbons) and apolar dyes into the microbowls.

Conclusions:

• The controlled buckling method provides a versatile approach for creating tunable microstructures.
• The elasticity of the capsule wall and residual PDMS oil facilitate the uptake of diverse oils and dyes.
• This technique offers potential for developing advanced micro-containment and delivery systems.