Carbon dots promoted photonic crystal for optical information storage and sensing

Photonic crystals (PCs) with crack-free morphology, high-saturated structural color and sensitivity to circumstances are expanding their applications in painting, sensor, optical coding and information technology. Herein, we incorporated functionalized carbon dots (CDs) onto polystyrene@poly(methyl methacylate-co-acrylic acid) (PS@P(MMA-AA)) colloidal particles via strong covalent bonding. Thanks to the abundant hydrogen bonding groups on the CDs, as-prepared CDs/PS@P(MMA-AA) PC film exhibits highly-crystalline morphology, brilliant structural color and fluorescence characteristics. By means of microfluidics technique, CDs/PS@P(MMA-AA) PC supraballs with angle-independent structural color for optical display and encoding are also demonstrated. Moreover, the magnetism/optics dual-functional Janus and hierarchical molecular-analogue supraballs are fabricated through the triphase microfluidic device and magnetism-induced assembly, bringing about a switchable behavior of PC supraballs in external magnetic field, which are further employed as the pixel points in the panel to store and display the quick response (QR) code information. Ultimately, combined with sensitive hydrogel, the CDs/PS@P(MMA-AA) PC hydrogel is not only imparted with an intriguing mechanochromic property, but also showing the rapid response to pH value. The CDs promoted PS@P(MMA-AA) PCs with various attractive optical properties offer a potential strategy of robust PC film/supraball construction for anti-counterfeiting, optical display, sensors and antireflection coatings.