Preparation And Characterization Of Low Density Titanium Dioxide/Polymethylmethacrylate Composite Particles For Electronic Paper Application

With the rapid development of the science and technology, vast quantities of information spread by internet in the form of electronic documents nowadays. Light flexible and portable display system in many fields, such as electronic newspapers, e-books and indoor/outdoor advertising etc., have attracted extensive attention by researchers in display filed. Electronic paper, which is flexuous and analogous as papers, is a new type of display. Meanwhile, it posses lots of features, such as lower power d.c., low-cost, high contrast and resolution. Currently on the market electronic paper mostly prepared by electronic ink technology, which is a kind of multiphase functional material and its research focused on the preparation of electrophoretic particles and display microcapsules.As important parts of electronic ink, electrophoresis particles are charged or easily charged by charge control agent particles, suspended in electrophoretic media and can produce electrophoresis to display image under the electronic field. Electrophoresis particles have a wide rang of choices, which can be a kind of any charged or easily accessed charges particles. TiO₂ particles are commonly used as electrophoresis particles because of its perfect refractive effect and excellent whiteness. However, since TiO₂ has relatively high density (density, 3.90 g/cm³), the density mismatch causes the severe sedimentation problem in the suspending media (density, 1.60 g/cm³), which can affect the use of display devices.Aiming at lowering the density mismatch between TiO₂ and the media, lots of researchers have coated TiO₂ with different polymers to prepare the suitable density composite particles. However, there are some disadvantages. For example, some studies have been carried out in the toxic organic solvents such as methanol or chloroform. In this paper, the low density TiO₂/PMMA composite particles were prepared by aqueous solution polymerization and emulsifier-free emulsion polymerization in water medium. The main content of this paper is the influence of MMA usage to the component, morphology, suspended thermal analysis density and other related properties of samples. Here, the conclusion as follows:1. Literatures show that lots of researchers have coated TiO₂ with different polymers in poison solvents, such as methanol and chloroform. Through relevant experiment scheme argumentation and experiment of feasibility analysis, the low density TiO₂/PMMA composite particles were prepared by aqueous solution polymerization and emulsifier-free emulsion polymerization in water medium.2. The low density TiO₂/PMMA composite particles with an average grain size of 189 nm and a thermal analysis density of 1.55 g/cm³, which matched well with the suspending media and had good dispersion, were obtained via aqueous solution polymerisation in the presence of polyvinylpyrrolidone.3. Based on MPS modified TiO₂, the low density TiO₂/PMMA composite particles with an average grain size of 302 nm and a thermal analysis density of 1.39 g/cm³, which matched well with the suspending media and had good dispersion, were prepared successfully via emulsifier-free emulsion polymerization in water.4. Under the physical adsorption of PVP and the chemical bonding of MPS, the low density TiO₂/PMMA composite particles, which were acquired by coated anatase TiO₂ with PMMA polymer, were prepared via aqueous solution polymerization and emulsifier-free emulsion polymerization in water. Adopting above experiment methods have avoided using poisonous organic solvent in the preparation of inorganic/polymer composite particles and provided new ideas to researchers who focuses on the study of composite particles. Meanwhile, above-mentioned methods have a great practical significance in production costs and environmental protection.