In this study, we fabricate magnetic–fluorescent
responsive
Janus photonic crystal beads (JPCBs) based on poly(styrene-methyl
methacrylate-acrylic acid) (p(St-MMA-AA)) colloidal nanoparticles,
Fe3O4, and photobase generators used for self-destructive
anti-counterfeiting. We synthesize two kinds of photobase generators
that can react with fluorescamine to produce various fluorescence
colors. A microfluidic method is used to obtain the Janus photonic
crystal beads. The upper portions of the JPCBs are photonic crystals
assembled with colloidal spheres, whereas the Fe3O4 settles down to the bottom of the JPCBs due to its higher
density. Photobase generators are distributed in photonic crystal
gaps. Because of the magnetism of the Fe3O4,
the JPCBs could be flipped from one side to the other in the presence
of a magnet. After being exposed to UVC light and fluorescamine, the
JPCBs can fluoresce under UVA light. Then, we create Janus microbeads
arrays with various types of beads and apply them to the visitor card,
bracelet, and box label to provide irreversible and self-destructive
anti-counterfeiting. The JPCBs are capable of being encoded and angle-independently
displayed, which are crucial to their applications in anti-counterfeiting,
information coding, and array display.