Application of ionic liquids as charge control agents of pigments and preparation of microcapsules as electronic inks through electrospraying

Abstract In the present study, we have used two ionic liquids (ILs) with different alkyl chain lengths belonging to the imidazolium family to prepare electronic ink (E-Ink). To apply bromide as an anion, compounds such as 1-Butyl-3-methylimidazolium bromide and 1-octadecyl-3-methylimidazolium bromide were utilized as charge control agents. We prepared the E-Ink containing copper phthalocyanine blue15:3 (PB15:3) nanoparticles, which had been modified with ILs in tetrachloroethylene (PCE). As-prepared samples were characterized using Fourier-transform infrared technique, thermogravimetric analysis, high resolution transmission electron microscopy, field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, X-ray diffraction, dynamic light scattering and ζ-potential approaches. Based on the obtained results, ILs had been successfully covered onto the surface of PB15:3 nanoparticles. Thereafter, to prepare E-Ink microcapsules, the electrospraying method with a coaxial nozzle was used. According to optical microscopy data, the size of microcapsules was smaller than 200 μm. Application of ionic liquids improved zeta potential and electrophoretic mobility properties. In the future, these materials and their modified structures can be considered as appropriate candidates for application as molecular charge control agents. Moreover, we demonstrated that electrospraying is a suitable approach for producing E-ink microcapsules.