Preparation Of High Response Rate Electrophoretic Particles With Low Density, And Microcapsules For Electronic Ink

Electronic paper has developed quickly since the media lab of MIT proposed the concept of microcapsule type of electrophoretic display for the first time at the end of 1990s. And more and more international corporations have been entering the electronic paper market in the past ten years.Highly monodispersed blue P(St-VBTAC-DVB) organic electrophoretic particles were successfully prepared by soap-free emulsion polymerization with an ionic comonomer vinylbenzyl trimethyl ammonium chloride (VBTAC). The particles were systematically characterized by Fourier Transform Infrared (FTIR) spectroscopy, Nuclear Magnetic Resonance (NMR), UV/vis Spectrometry, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), particle size analysis and zeta potential analysis. We found that, the particle size, the dye content and the zeta potential of the particle could be controlled by varying the content of ionic comonomer VBTAC, the acetone/water volume ratio, or the content of the oil blue N. We prepared highly monodispersed organic electrophoretic particles in the range of 76-246 nm. The maximum zeta potential of the particles in octane is 32.1 mV, and the maximum mobility rate of them is 6.76×10^-6 cm²s^-1V^-1 in the presence of charge control additives.Polystyrene/titania(PS/TiO₂) core-shell particles were successfully prepared by sol-gel method. The PS/TiO₂ particles were systematically characterized by SEM, TEM, particle size analysis and zeta potential analysis. We found that, the addition of PVP in the preparation influenced the property of final particles. Compared to added tetrabutyl titanate(TBT) in the reaction system, adding NaCl solution into the reaction system made the TiO₂ layer thicker and more dense. Adding NaCl solution into the reaction system could prepare core-shell particles, while adding citrate acid could't prepare it. We prepared the TiO₂ layer thick in the range of 5-65 nm by controlling the concentration of TBT. We prepared PS/TiO₂ core-shell particles in the range of 176-236 nm with the density of 1.29g/cm³-2.82 g/cm³.The maximum zeta potential of the particles in octane is 42.0 mV, and the maxium mobility rate of them is 8.84×10^-6 cm²s^-1V^-1 in the presence of charge control additives. Microcapsules containing hexadecane as core material were prepared from polymethyl methacrylate (PMMA) by the solvent evaporation method. Systematic investigation for the influence of PMMA/hexadecane mass ratio, surfactant PVA concentration as well as stirring speed on the capsule diameter and capsule size distribution was carried out. It is found that the diameter and the particle size distribution of the capsules increase with the increase in PMMA/hexadecane mass ratio, while decrease with the increasing the stirring speed and the amount of PVA. The capsules prepared under conditions of PMMA/hexadecane mass ratio of 1:4, PVA content of 2%, stirring speed of 1000 rpm, temperature of 35℃, and can be applied in eletrophoretic display.