Preparation of PS/TiO2 as a white pigment for electrophoretic displays

PS (polystyrene)/TiO2, TiO2 coated onto PS by a hydrolysis reaction, was prepared as a white pigment for electronic paper (e-paper). Two key parameters, density and zetapotential, were precisely controlled for use as a white pigment. The density was manipulated by changing the mixture ratio of EtOH to H2O, and the concentration of titanium tetrabutoxide (TBO) in the hydrolysis reaction. The modification of PS/TiO2 with (3-aminopropyl)triethoxy silane (APTES) and acetic acid showed positive zetapotential originated from the mutual effects between an amino functional group in APTES, and a proton from acetic acid. The mutual effect was studied, and PS/TiO2 with density of 1.6 g/cm2 and zetapotential of 75 mV was prepared using the results.