Multistage safety code based on responsive CdS photonic crystal organohydrogel

In the realms of information storage and display, achieving heightened levels of complexity and security has always been paramount. This study presents a multi-responsive material based on CdS photonic crystals, harnessing the properties of CdS photonic crystals and responsive organohydrogels. We incorporated temperature-responsive monomer N-isopropyl acrylamide (NIPAM), AIE monomer (2-(4-vinylphenyl)ethene-1,1,2-triyl)tribenzene (TPEE), and photochromic unit 2,2-diphenyl-2H-naphtho [1,2-b] pyran-6-carbaldehyde (naphthopyran, Np) into the organohydrogel to prepare the responsive gel material. It was then combined with CdS photonic crystals to fabricate the multistage responsive CdS photonic crystal organohydrogel. This material is not only capable of tuning the structure color of the photonic crystals through temperature but also triggers the AIE effect of the gel upon reaching the phase transition temperature. Additionally, it can initiate the photochromic effect of the material upon exposure to ultraviolet (UV) light. These responsive behaviors underpin the multistage response nature of the material. Capitalizing on these multi-responsive traits, we designed an array of multistage responsive anti-counterfeiting patterns and multistage security codes. This approach not only elevates the density of multi-layered information storage but also fortifies the tamper-resistance of traditional coding systems. The multistage responsive material has a wide spectrum of potential applications, particularly in anti-counterfeiting, information display, and encrypted data transmission, offering fresh perspectives in the domain of information security.