Preparation and Characterization of Hollow TiO_X Nano-Spheres for Electrophoretic Displays

Abstract

Hollow TiOX nano-spheres have been successfully prepared using hollow core-shell latex particles as template, which involves the deposition of inorganic coating on the surface of hollow core-shell latex particles and subsequent removal of the latex particles by calcinations in air or ammonia gas. The formation route of hollow core-shell polymer particles is presented as follows: Firstly, poly-methyl methacrylate (PMMA) seed emulsions are prepared as the 'core'. Subsequently, the outer shell poly(styrene-co-methyl methacrylate) (PS-co-MMA) particles wrap on the surface of the core, the microspheres with core-shell have been prepared. Finally, Ti(OBu)4 is used as precursor for the preparation of hollow TiOX nanospheres. Transmission electron microscopy (TEM) and atom force microscopy (AFM) images of seed emulsions show they have the uniform size of about 470 nm. TEM of hollow core-shell polymers particles show they have an average diameter of about 500 nm. X-ray diffraction (XRD) analysis of TiO2 sample calcined presents that the strong absorptions is coordinated with the standard chart of rutile TiO2. TEM of TiO2 and TiO show hollow spheres well-dispersed with the diameter range of 300-400 nm and 350-400 nm, respectively. The density (in the atmospheric pressure, 20 °C) of TiO2 and TiO hollow spheres was 2.49 and 2.37 g∙mL-1, respectively. The Zeta potentials were 6.20 mV and 20.39 mV, respectively. Uniform hollow spheres show low density and good electrophoretic displays. The electrophoretic mobilities of white TiO2 and black TiO hollow spheres in tetrachloroethylene show they are suitable for electronic paper as background and display particles, respectively. It is anticipated that this method would present a potential toward the road of large-scale industrial production of TiOx hollow spheres.

Core–shell nanoparticles: synthesis and applications in catalysis and electrocatalysis

“…A slightly different approach for the preparation of hollow-coreshell mesoporous TiO 2 has been reported 156 using a stepwise protocol based on seed-emulsion-polymerization, followed by coating of the Ti-precursor and subsequent calcination to generate hollow TiO 2 materials for electrophoretic studies. 157,158 Ohtani and co-workers adopted a similar procedure involving solvothermal and calcination techniques for the synthesis of SiO 2 /void/TiO 2 (and also platinized SiO 2 /void/TiO 2 ). 159,160 These photocatalytically active materials were used in the stereoselective synthesis of pipecolinic acid.…”