Water rewriteable double-inverse opal photonic crystal films with ultrafast response time and robust writing capability

Abstract

Photonic paper, as a crucial branch of the research of structural color materials, has attracted considerable attention. Herein, innovative large-area water rewriteable double-inverse opal (WRDIO) film with ultrafast response time (∼0.8 s) and robust writing capability is fabricated by introducing polyacrylamide gel into the double-inverse opal. The hydrophilic nature of the polyacrylamide gel can induce water to quickly penetrate the internal pores of the inverted opal backbone. Simultaneously, the randomly distributed polystyrene microspheres within the pores become ordered under the action of liquid buoyancy, which eliminates the scattering disturbance and makes the film switch to the structural color state. Importantly, the as-prepared WRDIO film can be erased and rewritten over 500 cycles without significantly reducing the color quality. Besides, the retention time of the written marks can be controlled by writing using water pens with different water outputs. Interestingly, responsive spatio-temporal colorful patterns could be achieved based on the different volatilities of written marks. Furthermore, advanced optical anti-counterfeiting material with multistate switching for information security is prepared based on controlled wettability. Given these superior properties, this novel WRDIO film provides a new solution for future applications of rewriteable paper.