Microencapsulation of Electrophoretic TiO₂ Nanoparticles for Electronic Ink

ABSTRACT

Microencapsulation of electrophoretic dispersion is one of the key steps in realizing the portable electrophoretic display technique, electronic paper. In this study, electrophoretic TiO₂ nanoparticles were uniformly dispersed in a dielectric medium of halocarbon oil and the TiO₂ based core material was emulsified using a polymeric surfactant of poly(sodium 4-styrene sulfonic acid) (PSSA). After the colloid particles were stabilized, the microencapsulation of the core materials was accomplished by the polycondensation of melamine/urea-formldehyde prepolymer. Average diameter of the microcapsules obtained was about 50 μm and their thermal stability was measured by TGA. The surface morphology of the microcapsule was dependent on the molar ratio of melamine/urea to formaldehyde and the water content.

Keywords:

• amino prepolymer
• electrophoretic ink
• microencapsulation
• nanoparticle
• TiO₂

Acknowledgments

This work was supported by the Strategic Research Projects of Inha University, Korea (2003)