Facile construction of dual bandgap optical encoding materials with PS@P(HEMA-co-AA)/SiO2-TMPTA colloidal photonic crystals

•High-capacity optical encoding materials derived from photonic crystals are proposed.•Janus colloid photonic crystal supraballs show dual structural colors and reflex.•Dual signals can be integrated into one photonic unit for accurate analysis.•Colorful “Flower” pattern has been constructed from photonic crystals by silk-screen technique.

An operable strategy for the construction of dual-reflex optical code materials from bilayer or Janus-structure colloidal photonic crystals (CPCs) has been established in this work. In this process, monodispersed submicrometer polystryene@poly(2-hydroxyethyl methacrylate-co-acrylic acid) hydrogel microspheres with soft-shell/hard-core structure and monodispersed colloidal silica spheres were fabricated. These two kinds of colloidal units can be facilely integrated into a single material without optical signal interference because they are well isolated for the immiscibility between water and ethoxylated trimethylolpropane triacrylate (TMPTA) and the upper layer of SiO2-TMPTA is a kind of transparent. Moreover, diverse optical code series with different dual photonic bandgaps can be obtained via tuning the colloid sizes. Compared to the conventional single-reflex CPCs, the as-prepared dual-reflex optical code materials represented high information capacity in encoding process. More interesting, delicate code pattern has been also achieved on the optical film via the silk-screen printing technique, which will greatly extend the dual-reflex optical code materials to practical uses in areas containing bio-encoding, anti-counterfeiting, and flexible displays.

Graphical abstractBilayer photonic crystal films and Janus supraballs were facilely fabricated via a layer-by-layer colloidal stacking method and a triphase microfluidic technique.Figure optionsDownload full-size imageDownload high-quality image (303 K)Download as PowerPoint slide