Inkjet Printing of Magnetically Responsive Photonic Crystals

Magnetic colloidal nanocrystalline clusters (MCNCs) exhibit a color‐changing response to a magnetic field due to their tunable assembly into photonic crystals demonstrating visible light diffraction. The use of this response to obtain a magnetically sensitive color micropattern on the surface of a solid substrate requires appropriate scalable technologies for deposition of MCNCs. Here, inkjet printing of MCNCs onto the surface of a solid substrate coated with uncured polydimethylsiloxane is addressed and demonstrate their capability to form desired patterns with structural colors from blue to red controlled by external magnetic field. The results, thereby, pave the way to semi‐commercial manufacture an anticounterfeiting imaging at a large scale. Magnetically sensitive micropatterns are obtained by inkjet printing on uncured polydimethylsiloxane. The ink consisted of synthesized magnetic colloidal nanocrystal clusters with proper surface modification. Nanocrystal clusters formed photonic crystals under applied magnetic field and provided a tunability of structural color.