A facile two-step approach to synthesize monodisperse and high-magnetization Fe₃O₄@PS composite colloidal particles for constructing dual-response photonic crystals

Monodisperse Fe₃O₄@PS colloidal particles with hollow core/shell structure and high saturation magnetization were successfully fabricated by a facile chemical approach. Owing to magnetic nature of iron oxide core and positively charged polystyrene shell, the colloidal particles in suspension assembled into ordered array and showed dual-response behavior to magnetic and electric field. When the cooperation between magnetic and electric field matched well, the photonic crystals showed better structural color and higher reflectivity. Consequently, as-synthesized Fe₃O₄@PS colloids have great potentials in some high-tech fields such as color sensors, color display, camouflage, electronic papers, and so on.