Microcapsules by Complex Coacervation for Electronic Ink

Abstract

Electrophoretic TiO₂ nanoparticles in a low dielectric medium can be utilized in non-emissive flexible display such as an electronic paper. To prevent the aggregation and to reduce the density of neat TiO₂ nanoparticles, the surface of TiO₂ particles was modified by acrylic copolymer. The surface modified TiO₂ nanoparticles, which were dispersed in low dielectric oils, were encapsulated by the complex coacervation of gelatin and gum Arabic. Then, core-shell type microcapsules were eventually fabricated. The capsules were crosslinked by the reaction between glutaraldehydes and amino groups in gelatinto improve the durability of the microcapsules. These microcapsules were stable during vacuum drying and were easily layered on the surface of the ITO substrates because of their flexibility. A simple electrophoretic display cell was constructed and both the color change and the response time were monitored.

Keywords:

• complex coacervation
• electrophoresis
• encapsulation
• nanoparticle
• titanium dioxide (TiO₂)

Acknowledgments

This work was supported by the Strategic Project of Inha University and by the Brain Korea 21 Project in 2005.