Fabrication and characterization of core-shell structured black pigment particles for electrophoretic display

To prepare electrophoretic black particles with good suspension stability in the low dielectric medium for the electrophoretic display application, black pigment (B444) as a core material and polystyrene (PS) as a shell material were prepared via dispersion polymerization of styrene, and then the fabricated B444/PS composite particles were positively charged with 2-(methacryloyloxy) ethyl trimethylammonium chloride. Morphology of the B444/PS core-shell particles was observed by scanning electron microscopy, while their chemical structure was confirmed via an FT-IR. Maximum values of the electrophoretic mobility and zeta potential observed by dynamic light scattering reach 4.46 x 10(-6) m2/Vs and 30.23 mV in a low dielectric medium, respectively. The resulting B444/PS particles also showed good electrophoretic movement in the B444/PS particle embedded microcapsules. Therefore, it can be applied in the dual-particle electrophoretic dispersion together with negative charged TiO2, showing black and white images.