Silica-shell/oil-core microcapsules with controlled shell thickness and their breakage stress

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Core-shell microcapsules are vital for encapsulating, protecting, and distributing active materials.
• Controlling shell properties is key to optimizing microcapsule performance.

Purpose of the Study:

• To develop core-shell particles with silicone oil cores and controllable silica-like shells.
• To investigate the relationship between shell thickness and particle mechanical strength.

Main Methods:

• Utilized surfactant-free condensation polymerization of diethoxydimethylsilane (DEODMS) for silicone oil (polydimethylsiloxane, PDMS) core templates.
• Formed silica-like composite shells via co-condensation of tetraethoxysilane (TEOS) and DEODMS.
• Controlled shell thickness by adjusting precursor concentrations or quenching shell development.
• Incorporated dyes into the core before shell formation.
• Applied controlled compression stress using micromanipulation and quantified breaking force via SEM ultramicrotomy.

Main Results:

• Successfully created monodisperse PDMS-in-water emulsions as core templates.
• Developed solid silica-like composite shells with tunable thickness.
• Demonstrated that shell thickness is directly proportional to the capsule breaking force.
• Confirmed dye containment within the core, with no observed shell permeation.

Conclusions:

• Developed a method for fabricating core-shell microcapsules with tunable shell thickness and mechanical properties.
• Established a direct correlation between shell thickness and the force required to break the capsules.
• Highlighted the potential for these microcapsules in applications requiring controlled containment and protection of active substances.