Collaborative “Dual-Step” Stimuli-Responsive Polymer Dye and Its Applications in Information Encryption

Information encryption is essential for information security. However, constructing a collaborative multiple-information encryption system with elaborate design and intuitionistic displays is challenging. In recent years, owing to their wide applications in sensing, intelligent switch, and information encryption, stimuli-responsive fluorescent materials have attracted the attention of scientists. Inspired by the multi-component collaborative step-by-step strategy from biology, we designed and synthesized a collaborative “dual-step” stimuli-responsive fluorescent copolymer poly(NIPAm-co-1-vinylimidazole-co-Rh-2) (PNVRh-2) with high color contrast and good reversibility (>10 cycles) after treatment by multiple stimuli. Using this strategy, we introduced rhodamine units with an acid-induced ring-opening effect and an electron-rich imidazole side chain into poly(N-isopropylacrylamide) (PNIPAm). By combining these components, the conventional one-step acid-induced luminescence process was transformed into a dual-step luminescence process triggered by acid and heat. The fluorescence rate and intensity of PNVRh-2 could be manipulated by adjusting the pH and temperature. Contactless thermoprinting and erasable imaging were achieved. Furthermore, the great potential of PNVRh-2 in programmatic temperature-controlled information display and information encryption was illustrated, which offers a perspective for designing and optimizing high-performance information encryption materials.