Electrophoretic display (EPD) is a type of flexible display which has attracted wide attention. In this work, blue nanosized crystals of cobalt aluminum oxide (CoAl2O4) were precipitated on silica nanoparticles, and then the nanocomposites were coated with an ionic liquid polymer (PIL) to give blue electrophoretic particles. The blue nanocomposites (SCAs) formed possess an excellent spherical structure, and the average diameter is about 188 nm. The porous silica matrix presents a relative light density, and the blue CoAl2O4 pigment offers excellent color. The outside ionic liquid polymer supplies the PIL/SCAs with a light density of 1.7915 g cm−3, excellent hydrophobicity and dispersion stability in the electrophoretic liquid. The fabricated single-particle EPD prototypes show a response time of 165 ms in the EPD cell with a 0.2 mm thickness, which is much faster than the commercial EPDs, and this is probably because of the unique composite structure.
