Preparation Of High Response Rate And Contrast Ratio Black/White Particles Electrophoretic Dispersion

Electrophoretic image Display, owing to its adavantages including reflection-type, low power consumption, flexibility, and ultra thin, has attracted widely attention in the scientific and industial area.TiO2 particles, employed as white electrophoretic particle, were treated by polybutene-succinimide pentamine and grafted with polymer via situ polymerization. The particles were characterized by means of FTIR spectroscopy, Transmission electron microscopy, gel permission chromatography, thermogravimetric analysis, Zeta poterntial etc. The particles treated by polybutene-succinimide pentamine and grafted with polymer dispersed well in tetrachloroethylene, and the highest Zeta potential were 42.7mV,-35.2mV respectively.Ferroferric oxide/silicon oxide (Fe3O4/SiO2) composite particles were prepared via in-situ sol-gel method by enwrapping as prepared pigment, Fe3O4 nanoparticles, into SiO2. The morphology and average particle size of Fe3O4/SiO2 core-shell composite particles were detected by transmission electron microscopy, scanning electron microscope, X-ray Diffraction and particle size analyzer. The polybutene-succinimide pentamine treated composite particles can suspend in the low dielectric medium stably. Zeta potential of the treated composite particles in tetrachloroethylene was measured to be 24.2mV.To improve the surface interaction with charge control agent and the pigment, carbon black and copper chromite were encapsulated by SiO2 shell, respectively. Polymer grafting carbon black and copper chromite dispersed well in nonpolar solvent.Acrylics copolymer acting as charge control agent was prepared by solution polymerization. It was demonstrated that the copolymer could efficiently improve the dispersivity and surface charge of pigment in nonpolar solvent. Zeta potential of particles in tetrachloroethylene increased with the increasing concentration of copolymer in dispersion. The highest of Zeta potential was 60.9mV. The dual-particles electrophoretic dispersion with high performance was studied. The dispersion with carbon black treated by copolymer and TiO2 grated with poly (Lauryl methacrylate) was the best in all samples. The contrast ratio increased with electric field and the mass of carbon black, under an electric field of 0.075V/μm, the highest contrast ratio is about 36:1 and the responding time is about 1s, it was much better than the single particle electrophoretic dispersion and could meet the requirement of electrophoretic image display.