Preparation Of The High Mobility Of Ps / Tio <sub> 2 </ Sub> Core-shell Structure Electrophoretic Particles

Electrophoretic displays (EPID), owning to its excellent performances, had attracted a great deal of commercial and academic interests during the past ten years.This paper devoted to preparing low density polystyrene/titania (PS/TiO₂) core-shell particles and high mobility dielectrophoretic particles for electrophoretic displays.The monodispersed positively charged PS particles were prepared via dispersion polymerization in an ethanol/water medium. Then titania shells was fabricated by hydrolysis and condensation of tetra-n-butyl titanate (TBT). The PS/TiO₂ core-shell particle was characterized by scanning electron microscopy (SEM), flourier transform infrared spectroscopy (FTIR) measurement and thermogravimetric analysis (TGA). The results gave a direct and clear evidence for the TiO₂ shell on PS core particles, and the density of PS/TiO₂ core-shell particles was lower than TiO₂ particles, which could help enhanced the charge/mass ratio of the dielectrophoretic particles for electrophoretic displays.The particles of polybutene-succinimide pentamine coated PS/TiO₂ were fabricated by self-assembly preparation. Zeta potential and mobility of polymer coated PS/TiO₂ particles in non-aqueous medium were measured by PALS zeta potenial analyzer. It was demonstrated that polymer coated particles in non-aqueous were charged and could migrate under the influence of electric fields. Dispersion stability depended not only on the density matching between particles and solvent, but also on the steric stabilization. Compatibility enhanced chains of PS/TiO₂ particles extend into the good solvent medium and interact positively with the binder molecules and the solvent. The zeta potential of polybutene-succinimide pentamine coated PS/TiO₂ particles was 44.3 mV, and the mobility was 1.03×10^-5 cm²/(V·s).