Preparation of microspheres by an emulsification-complexation method

Area of Science:

• Materials Science
• Polymer Chemistry
• Colloid Science

Background:

• Microsphere formulation is crucial for drug delivery and material science applications.
• Controlling microsphere size and properties is essential for optimizing performance.
• Complexation between charged polymers and surfactants offers a route to novel particle formation.

Purpose of the Study:

• To develop a method for preparing polyquaternium-24 and sodium lauryl sulfate (SLS) microspheres.
• To investigate the effect of preparation parameters on microsphere characteristics.
• To understand the mechanism of microsphere formation via complexation.

Main Methods:

• Preparation of polyquaternium-24 in a water-in-silicone (W/Si) emulsion.
• Dispersion of the W/Si emulsion into a sodium lauryl sulfate (SLS) solution.
• Characterization of droplet and microsphere formation using X-ray energy dispersive spectra.
• Evaluation of the impact of stirring rate on microsphere diameter.

Main Results:

• Successfully prepared microspheres through the complexation of polyquaternium-24 and SLS.
• Identified two distinct droplet types: silicone droplets and polymer-surfactant microspheres.
• Demonstrated that increasing stirring rate from 300 to 1000 rpm reduced mean microsphere diameter from 105.7 to 64.8 µm.
• Confirmed microsphere composition via X-ray energy dispersive spectra.

Conclusions:

• The complexation of cationic polyquaternium-24 and anionic sodium lauryl sulfate (SLS) effectively forms microspheres.
• The stirring rate during W/Si emulsion preparation is a critical factor in controlling microsphere size.
• The proposed mechanism involves the solidification of water droplets within the emulsion upon exposure to the surfactant solution.