Mechanical properties of polyelectrolyte-filled multilayer microcapsules studied by atomic force and confocal...

Area of Science:

• Materials Science
• Physical Chemistry
• Biophysics

Background:

• Multilayer microcapsules are advanced delivery systems.
• Understanding their mechanical properties is crucial for applications.
• Polyelectrolyte solutions influence capsule behavior.

Purpose of the Study:

• To investigate the deformation properties of polyelectrolyte-filled multilayer microcapsules.
• To correlate mechanical response with internal structure and shell permeability.
• To analyze the effect of osmotic pressure on capsule stiffness.

Main Methods:

• Utilized atomic force microscopy (AFM) for force-deformation analysis.
• Employed confocal microscopy to study internal polyelectrolyte distribution.
• Controlled polyelectrolyte encapsulation via shell permeability regulation in water-acetone solutions.

Main Results:

• Filled capsules demonstrated greater stiffness than hollow ones, attributed to osmotic pressure.
• Force-deformation curves showed three distinct regimes: reversible, partially reversible, and irreversible.
• Deformation regimes were linked to water and polyelectrolyte permeability through the multilayer shell during compression.

Conclusions:

• Osmotic pressure significantly enhances the stiffness of polyelectrolyte-filled microcapsules.
• Microcapsule deformation behavior is complex, involving multiple stages.
• Shell permeability plays a critical role in the mechanical response and structural integrity of microcapsules under compression.