Emulsion Stabilization Strategies for Tailored Isocyanate Microcapsules.

Area of Science:

• Materials Science
• Polymer Chemistry
• Colloid Science

Background:

• Developing stable emulsions is crucial for producing uniform microcapsules via interfacial polymerization.
• Isophorone diisocyanate (IPDI) microcapsules are valuable crosslinkers for advanced adhesive formulations.
• Controlling microcapsule morphology and size distribution impacts adhesive performance.

Purpose of the Study:

• To investigate emulsion stabilization methods for producing polyurea microcapsules containing IPDI.
• To evaluate the impact of different stabilizers on emulsion properties and microcapsule characteristics.
• To optimize microcapsule synthesis for enhanced performance in adhesive applications.

Main Methods:

• Oil-in-water (O/W) emulsion preparation using gum arabic, Dabco®DC193, and polyvinyl alcohol (PVA) as stabilizers.
• Emulsion stability assessment through sedimentation studies and droplet size analysis using optical microscopy.
• Microcapsule characterization via scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA).

Main Results:

• Polyvinyl alcohol (PVA) as a rheology modifier significantly improved emulsion stability, reducing droplet sedimentation.
• PVA enabled the production of spherical, core-shell polyurea microcapsules with a narrower size distribution (approx. 40.9 µm mode).
• High encapsulation yield of 46 wt% IPDI was achieved, with stabilizers other than DC193 producing desirable microcapsule morphology.

Conclusions:

• Emulsion stability is a critical factor in controlling microcapsule morphology, size, and distribution.
• Optimized emulsion stabilization using PVA leads to high-quality IPDI-containing microcapsules suitable for adhesive formulations.
• The findings provide a pathway for tailoring microcapsule properties for improved homogeneity and performance in adhesives.