Structure-Colored Polymer Film Fabricated by Surface Immobilizing Amorphous Photonic Crystals

Amorphous photonic crystals display isotropic photonic band gaps and angle-independent non-iridescent, structural color, which leads to increasing interest and promising applications in image display, laser light, environment-friendly ink/coating, etc. However, previous amorphous photonic crystals usually exhibit low strength, and their structure is easily destroyed. Thus, their unique optical properties cannot be fully exhibited. Herein, amorphous photonic crystals of core (polystyrene-PSt) and shell (poly (4-methacryloyloxybenzophenone)-PMABP) structured microspheres are formed. Using polymer films (PET, PP, PMMA and PE) coated with poly (4-(methacryloxy) benzophenone-co-N-Isopropyl acrylamide) as substrates, the amorphous photonic crystals are immobilized under UV-irradiation. Adding cross-linker of ethoxylated trimethylolpropane triacrylate (ETPTA) in microsphere dispersion, transparent and flexible free-standing films of photonic crystals are fabricated. Angle-independent structural colors are observed and tuned by varying microsphere concentration in dispersions and content of cross-linker.