Clumping Between Carbon Black and Titanium Dioxide Pigment by Water Vapor Absorption and Its Correlation with Electrophoretic Display.

Carbon black and titanium dioxide have been widely used as pigment particles for electrophoretic displays. However, the effect of external water vapor on these pigment particles has not yet been presented. Therefore, in this work, we report the clumping phenomenon between pigment particles as a result of water vapor absorption. To verify clumping between pigment particles, various analysis techniques were used, including scanning electron microscopy, atomic force microscopy, zeta potential measurement, and Raman spectroscopy. We examined the Raman spectrum of carbon black to demonstrate the effect of water vapor absorption on particles. According to the Raman spectrum analysis, the 2D and 2D' peak intensities were significantly increased; moreover, the full widths at half maximum were modified. Thus, we concluded that water vapor absorption on pigment particles can induce the clumping phenomenon on pigments. To protect an electrophoretic display device from external gas transmission, we applied a nanocomposites gas barrier film to the device. The device lifetime was consequently improved by 336%.

Synthesis of anionic sulfate functionalized polystyrene latex and protein adsorption for application as a biosensor.

Bare and surface modified polystyrene nanoparticles with an anionic sulfate end group were synthesized by emulsion polymerization for adsorption of a protein (immunoglobulin G, IgG) by passive adsorption and electrostatic attraction for application as a biosensor. Dynamic light scattering (DLS) measurements confirmed the formation of an IgG-polystyrene latex complex, showing increased hydrodynamic diameter (D(h)) of approximately 178 nm (passive adsorption) and approximately 220 nm (electrostatic attraction) after IgG adsorption. An increased Zeta (zeta) potential value from -38.8 mV to -3.84 mV following IgG adsorption by electrostatic attraction also reflected the formation of the IgG-polystyrene latex complex. Solid phase immunodetection results demonstrated the formation of the IgG-polystyrene latex complex by showing fluorescent signals induced by FITC, which conjugated to IgG on the surface of the polystyrene. In addition, immunoassay results showed that adsorbed IgG on the polystyrene latex surface was not desorbed and maintained immunoreactivity after 1 month from the initial IgG-polystyrene latex complex formation.