Preparation and characterization of low density polystyrene/TiO2 core–shell particles for electronic paper application

In order to reduce the density mismatch between TiO2 and the low dielectric medium and improve the dispersion stability of the electrophoretic particles in the low dielectric medium for electrophoretic display application, polystyrene/titanium dioxide (PS/TiO2) core–shell particles were prepared via in-situ sol–gel method by depositing TiO2 on the PS particle which was positively charged with 2-(methacryloyloxy)ehyl trimethylammonium chloride (DMC). The morphology and average particle size of PS/TiO2 core–shell particles were observed by transmission electron microscopy (TEM), scanning electron microscope (SEM) and particle size analyzer. It was found that density of PS/TiO2 core–shell particles were reduced obviously and the particles can suspend in the low dielectric medium of low density. The PS/TiO2 core–shell particles can endure ultrasonic treatment because of the interaction between TiO2 and PS. Zeta potential and electrophoretic mobility of the fabricated core–shell particles in a low dielectric medium with charge control agent was measured to be −44.3 mV and −6.07 × 10−6 cm2/Vs, respectively, which presents potential in electronic paper application.