Polymer encapsulated inorganic black pigment nanoparticles and their electrophoretic characteristics

초록

Among various types of electronic-paper (E-paper) display, a microcapsule-type electrophoretic display technology dominates as one of the well developed and effective method due to its unique and desirable properties like lightweight, good contrast ratio, and wide-angle view [1]. The electrophoretic display is normally composed of micron-sized capsules inserted with charged particles, suspension fluid, charge controlling agent, and particle stabilizer. Once microcapsules are exposed to an electric field, these charged particles move either up or down within the microcapsules, making graphic images [2, 3]. Not only charged particles but also their zeta potential is therefore important since it is directly related to the electrophoretic behavior of the particles in a medium oil. In this study, we encapsulated inorganic black pigment with poly(styrene-co-acrylonitrile) to form electroresponsive hybrid nanoparticles. While vinylimadozole was added slowly during polymerization to enhance their charge mobility, a steric stabilizer of poly(acrylic acid) was also added to encapsulate inorganic particle with polymer more thickly by stabilizing chemical reaction. To optimize the proper amount of stabilizer, we changed the amount of steric stabilizer during polymerization. The fabricated hybrid nanoparticles were examined by SEM to confirm their morphology. The density and size of particle were investigated as well via gas pycnometer and dynamic light scattering (ELS-8000), in addition to their chemical structure and coated state via FT-IR and TGA. Electrophoretic characteristics of zeta potential of the particle and the movement of particles were further studied via ELS 8000 and optical microscopy, respectively, exhibiting their improved E-paper characteristics. This work was supported by the Ministry of Knowledge Economy, Korea and Kolon (2010).