外文翻译原文：聚甲基丙烯酸甲酯包裹二氧化钛纳米颗粒的制备和表征

Preparation and Characterization of Poly(Methyl Methacrylate) Coated TiO2Nanoparticles B. J. PARK, J. H. SUNG, K. S. KIM, I. CHIN, AND H. J. CHOI Department of Polymer Science and Engineering, Inha University, Incheon, Korea Titanium dioxide (TiO2 ) nanoparticles were modifi ed with poly(methyl methacrylate) (PMMA) to improve the dispersion stability of the nanoparticles in a dielectric medium and to reduce the density mismatch between TiO2and a dielectric medium for a microcapsule-type electrophoretic display application. Nanoparticles were coated with PMMA by in situ dispersion polymerization. The PMMA-coated TiO2 nanoparticles were characterized by fourier transform-infrared spectrometrey (FT-IR), electrophoretic light scattering (ELS), and scanning electron microscopy (SEM). Density of PMMA-coated TiO2nanoparticles was found to be dependent on the thickness of the PMMA coating on the nanoparticles. An increase of thermal stability of the PMMA layer and the contents of PMMA on the surface of the nano- particles were measured via thermogravimetric analysis (TGA). Keywordsdispersion, electronic ink, TiO2, nanoparticle Introduction Control of the colloidal properties and stability of titanium dioxide (TiO2) suspensions is of signifi cant importance in manufacturing diverse high-performance products such as paints, cosmetics, and photocatalysts to name a few.15TiO2nanoparticles are also studied for application in electronic ink-based fl exible displays, because of their high refractivity and excellent whiteness for good image contrast in dark suspension media.6The dispersion stability of TiO2nanoparticles is considered to be one of the most diffi cult problems to solve in electrophoretic display application. Recently there have been many attempts to enhance the dispersion stability of inorganic nanoparticles using several different methods.712 Surface modifi cation of the inorganic particles by coating with polymeric materials provided not only high electrostatic repulsion but also repulsion due to adsorbed polymer layers, known as steric repulsion. Moreover, the density mismatch between nanoparticles and the dielectric medium was decreased, due to the polymer layer having a lower density than that of the nanoparticles. Several methods, including in situ polymerization, to form core-shell structure for nanoparticles have been introduced.1317Poly(methyl methacrylate) (PMMA) is known to be suitable as a shell material to use to encapsulate inorganic Received 25 June 2005; Accepted 10 August 2005. Address correspondence to H. J. Choi, Department of Polymer Science and Engineering, Inha University, Incheon 402-751, Korea. 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