Formation of titanium dioxide core-shell microcapsules through a binary-phase spray technique

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Core-shell microcapsules offer unique properties for various applications.
• Developing efficient and scalable methods for microcapsule synthesis is crucial.
• Titanium dioxide (TiO2) shells provide desirable characteristics like UV resistance and biocompatibility.

Purpose of the Study:

• To develop a simple, fast, and scalable airbrush technique for producing titanium dioxide core-shell microcapsules.
• To investigate the encapsulation of hydrophobic solvents and an antifungal biocide within these microcapsules.
• To optimize the microcapsule formulation and processing parameters for high loading capacity.

Main Methods:

• Utilized a single-step airbrush technique at room temperature.
• Employed a titanium alkoxide precursor in a hydrophobic solvent core, combined with an aqueous solution containing a surface-active polymer.
• Investigated various core materials (alkanes, ketones, alcohols) and the antifungal biocide 2-n-octyl-4-isothiazolin-3-one (OIT).

Main Results:

• Successfully prepared core-shell microcapsules with titanium dioxide shells and hydrophobic cores, exhibiting micrometer diameters and narrow size distributions.
• Identified long-chain alcohols as suitable core materials due to low water solubility and surface activity.
• Achieved an impressive 50 wt% loading of the semi-hydrophobic OIT within the microcapsules.
• Demonstrated the importance of surface-active polymers in shell formation and stabilization.

Conclusions:

• The airbrush technique is a highly effective and applicable method for producing titanium dioxide core-shell microcapsules.
• This method allows for high encapsulation efficiency of hydrophobic active ingredients like OIT.
• The developed microcapsules hold potential for applications requiring controlled release of biocides or other hydrophobic substances.